IEEE 2020 3rd 5G World Forum, 10 September - 10 October, Virtual

In a keynote address presented to the 2020 IEEE 5G World Forum plenary session, Gerhard Fettweis from Technische Universität Dresdan discusses the next generation of communications technology beyond 5G and how advancements like AI and softwarization will impact its development.

For more information on the conference, visit the 5G World Forum website or the IEEE Future Networks Initiative website.

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A Sustainable Ecosystem Framework for 5G Applications & Services


Applications and services are the exciting place where technology advances and envisioned use cases
merge to reveal real world practices and impact. 5G and future networks have galvanized the imagination around a broad landscape of known and possible applications and services like no earlier network generation. But, what was missing was a way to organize and contextualize a sustainable infrastructure that can underlie applications and services across myriad industries. This podcast imparts a structured, flexible, adaptable, and scalable methodology for applications and services that extends end-to-end across ecosystems in urban and non-urban areas. This methodology caters to different levels of local priorities, resources, and technologies.

What is the benefit of this approach to industries, citizens, society? This methodology caters to different levels of local priorities, resources, and technologies. Communities may use the interconnected ecosystem of ecosystems framework to traverse across adjacent ecosystems to respond to planned or unplanned events.

This work is underway in the Applications & Services Working Group of the International Network Generations Roadmap.

View the International Network Generations Roadmap page with Executive Summary, and options for viewing the Applications & Services chapter.


Subject Matter Experts


Narendra Mangra
Co-chair, International Network Generations Roadmap
Co-chair, Applications & Services, Working Group, International Network Generations Roadmap
Principal, GlobeNet, LLC



With Brian Walker of IEEE Future Directions Digital Studio


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Podcast Transcript 


Brian Walker: Narendra, thank you for taking some time to contribute to the IEEE Future Network Podcast series.  You’ve talked about a sustainable ecosystem framework for 5G applications and services. Can you explain what that is and why we need it?

Narendra: Well, applications and services, when you think about it, is a fairly large area, and we needed a way to organize all the different types of applications and services we have. So, for example, we may have cases where we have a drone that may be used to deliver a pizza or may be used in a public safety context for determining situational awareness. So, the same application and services may be used in different ways and may have different requirements for that. That is the reason why we needed a conceptual framework that not only looks at it within the context of an ecosystem, but also among the different ecosystems to make sure that they’re connected, and they’re aligned with each other, as well as that it is also sustainable in that it is long-lasting. It is upgradable and actionable and it’s not something that we’re going to need to rip and replace very frequently, something that’s going to be there for some time.

Brian Walker: Do you see a common framework that can be effective across industries and applications?

Narendra: That’s an excellent question. We’ve thought long and hard about what are the best ways to approach the subject. We wanted something that has a common structure that we can build upon and is easy to understand across the spectrum. One area that we looked at is really more of a supply management framework. When I say that, I don’t necessarily mean it from a business aspect as far as business relationship, but more from an information flow. For example, if we’re looking at a continuum of care model for healthcare, we’re looking at a patient-centric information flow and best ways to optimize the supply chain across that ecosystem, and the same applies for an event-driven framework for public safety in a recovery continuum and mobility for multi-modal models for transportation and so on. Initially, we looked at five key ecosystems. That includes healthcare, public safety, electricity, water, and transportation. The new ecosystem that we’re targeting for the second edition [of the International Network Generations Roadmap] includes agriculture and education and entertainment.

Brian Walker: How is this overarching ecosystem of ecosystems approach more beneficial than current systems?

Narendra: That’s an excellent question, because that kind of follows from the framework that we’re using, in that we have the ability to break it down into different pieces, and what I mean by that is, for example, the public safety ecosystem. We can break that down into five different mission areas that include prevention, protection, mitigation, response, and recovery, and within each one of these areas then we can treat this independently, and that gives us a lot of flexibility as far as how do we align that particular ecosystem to make one stage work well with another, as well as looking at how different ecosystems are aligned. So, how does public safety impact healthcare and how does it impact transportation and so on?  We’re looking at also, are there inter-ecosystem interdependencies and touchpoints? And at the end, a community or a local leader can use that, whether it’s a municipality or even at the national level, can look at that and combine all of the different ecosystems at the stage they happen to be at, and that may be different across communities, and to be able to use that to achieve the common objective that they have.

Brian Walker: What are the pros and cons of different deployment approaches?

Narendra: One area that came out of the overall framework was, “How do we apply that? How do we make this practical and still provide an outlook between the 5-to-10-year mark?” We looked at the common method that’s used, it’s a use case classification that you may be family with, that’s enhanced mobile broadband, massive machine type communications and ultra-reliable low-latency communications, also known as URLLC, and that is great, because it has a key set of considerations that we should take into account, and they include high data rates, low latency, connection of traffic density, reliability, and so on. But we wanted to look at it from a different angle. We wanted to look at it functionally first. So, we broke that down into the different components of any future network considerations, and that includes the access component, whatever that may happen to be in a future network, and the service delivery. Some people may align or associate that with edge or core networks, for example. We’re looking also from an operations, and a network management, and a customer relationship point of view, and the fourth stage is also looking at it from a network interoperability point of view. So, it may be a cellular interoperability, or it may be cellular to some special-purpose network that we have. This allows us basically to take into account not only the technologies, but also the different constraints that may apply across the board or may be more localized in nature.

Brian Walker: What are the enablers of this approach?

Narendra: The primary enablers we’re looking at-- we’re looking at it from two different aspects. Within the ecosystem there may be certain drivers in place that we need to take into account that’s really more-- that is more aligned with that ecosystem. Key drivers, for example, healthcare, maybe HIPAA constraints or requirements, and we’re looking also from a common ecosystem enabled point of view, and they may differ in the degree of priority they have, but they certain apply across the board, and they include areas such as security, privacy, trust, position determination, artificial intelligence and machine learning, and so on. So, we take that into account for common enablers. We also have a very broad perspective, so we are open to different types of technology, whether it be satellite, terrestrial cellular, wi-fi, or even fixed network. We’re using a combination of all of this, and together we’re looking at it with a broad technology agnostic point of view to assess the different areas.

Brian Walker: How do you anticipate this approach will be a benefit in the event of extreme weather, a future pandemic, or other disruptive event?

Narendra: This framework could actually be used on a broad level and at a localized level. First and foremost, we can look at treating any of the extreme weather or pandemic or any other disruptive event, whether planned or unplanned, within its own respective ecosystem. What that means is, for example, case in point, COVID-19. We can look at it as a healthcare problem because it is. It is first and foremost a healthcare problem. So, we can see, “How can we adjust this, use this model for supply and demand mismatches?” and by using the supply chain construct, it may be information flow to help with increasing the manufacturing capabilities, the need for deployable converted hospitals and really making sure that we have the supply of care available where it is needed. From the demand aspect, we can look at it from the common methods such as social distancing, dissemination of information for preventative measures, and also to help with fitness development, which is also very helpful, to help prevent any areas related to healthcare. Secondly, we can use these this framework to see how does it touch different ecosystems?  So, COVID-19 we know impacts the workforce. We know it impacts the food supply chain and education and transportation, and the list goes on and on. If an event happened to be sustained, then it would create more of a shock to that particular industry that makes up that ecosystem, and that is something that we will also need to take into account for the model, and it does accommodate that need, and third and lastly, the communities may be able to use those combined capabilities that may be different, again, across the different areas just to use it for its full potential to address the common objective for that local area.

Brian Walker: Are non-technical areas such as privacy, trust, and ethics under consideration?

Narendra: Absolutely. This is a key consideration. In fact, we started working in these areas in the first edition, and we will build on them for the second edition as well. Data governance models, privacy and transparency, they’re essential, really, for developing contextualized data models and basically, to be able to optimize the different ecosystems so that we can continue to build and get value out of them.

Brian Walker: Where can people go to learn more about 5G applications and services?

Narendra: For the first edition, anyone listening can go to the IEEE Future Network International Network Generations Roadmap and they’re found at You will see the first edition for application and services, as well as the work from other working groups, and there’s also a webinar that was held in January 2020 that is also at the website and under the webinars tab, and you will be able to see all of the different working groups there.

Brian Walker: Thanks, Narenda. In closing, what would be your call to action for anyone listening to this podcast?

Narendra: We would love to have additional volunteers. We take a broad approach, as you can see, and we are looking for different volunteers with backgrounds in technology, ecosystems or different types of enablers that can help move the effort forward. We take an interdisciplinary approach to develop this, and really, what the end goal is. The hope is that we have more volunteers that could help provide diverse opinions, to provide a high-level perspective and projection of how the industry could evolve to highlight any common needs, to identify any of the challenges we have to achieving these needs, and to provide solutions. A diverse skillset is welcome, and aside from application and services, there’s also a number of working groups. In fact, there’s about 15 working groups so far and they address different diverse and challenging areas as well. Volunteers are definitely welcome, and we look forward to seeing more.

Brian Walker: Thank you for listening to this edition of the IEEE Future Networks “Podcasts with the Experts.”  Discover more about the IEEE Future Networks Initiative and inquire about participating in this effort by visiting our web portal at

Date: 16-18 June 2020 

Virtual Workshop via WebEx

For questions, please email This email address is being protected from spambots. You need JavaScript enabled to view it.  



  • Share key perspectives from industry, government, and academia
  • Review cross-team materials
  • Align and progress roadmap chapters’ content
  • Identify overall roadmap driver metrics, technical gaps, challenges
  • New members participation




Day 1: 16 June 202020 
Topic Speaker Related Content
Welcome and Introduction Brad Kloza / Narendra Mangra Session Recording 
 Testbed Ivan Seskar/Mohammad Patwary  Slides
Applications and Services Narendra Mangra 


Artificial Intelligence & Machine Learning Deepak Kataria, Anwar Walid


Standards Alex Gelman, Mehmet Ulema, Reinhard Schrage


Connecting to the Unconnected Sudhir Dixit, Ashutosh Dutta   Slides
 Satellite Giovanni Giambene, Sastri Kota, Prashant Pillai


Deployment David Witkowski, Tim Page, David Young


  Break/Afternoon Session

 Session Recording

Massive MIMO  Chris Ng, Webert Montlouis, Rose Hu


Systems Optimization  Meryem Simsek, Lyndon Ong, Kaniz Mahdi


EAP  Sujata Tibrewala, Prakash Ramchandran


Security & Privacy  Eman Hammad, Ashutosh Dutta


Energy Efficiency Brian Zahnstecher, Francesco Carobolante


mmWave & Signal Processing Tim Lee, Harish Krishnaswamy



June 17: Cross team meetings


    • Applications and Services = A&S
    • Edge Automation Platform = EAP
    • Hardware = HWR
    • Massive MIMO = MIMO
    • Satellite = SAT
    • Standardization Building Blocks = STAN
    • Security = SEC
    • Testbed = TEST
    • Energy Efficiency = EE
    • Deployment = DEP
    • Connecting the Unconnected = CTU
    • Systems Optimization = SYSOP
    • Artificial Intelligence & Machine Learning = AIML
 8AM  9AM  10AM 11AM  12PM  1PM  2PM 3PM 4PM  5PM 6PM 
         STAN   MIMO MIMO     SYSOP
         CTU   DEP STAN     TEST
            SAT SEC      
            AIML SYSOP      

June 17: Cross team meetings

 9AM 10AM  11AM  12PM  1PM  2PM 3PM  4PM  5PM 6PM 
        SEC     AIML    
        TEST     TEST    

International Network Generations Roadmap (INGR) Leadership Team:

IEEE Future Networks Initiative Co-chairs:

  •   Ashutosh Dutta – This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Timothy Lee -  This email address is being protected from spambots. You need JavaScript enabled to view it.

IEEE International Network Generations Roadmap Co-chairs:

  •   Chi-Ming Chen - This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Rose Hu - This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Narendra Mangra - This email address is being protected from spambots. You need JavaScript enabled to view it.

Thank you for your interest in the IEEE International Network Generations Roadmap (INGR). The reports are accessible to subscribers of the IEEE Future Networks Community, which does not require IEEE membership. To access, please follow the instructions below. 

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While the INGR Executive Summary is free to download, all other chapters are available exclusively to signed-in participants of the IEEE Future Networks Community.

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Additional INGR Edition 1 White Papers (available soon) 

Meng Lu, Dynniq The Netherlands, and Haesik Kim, VTT, Finland

IEEE Future Networks Tech Focus Volume 3, Number 2, September 2019 

Europe has launched in 2019 a research and innovation project on 5G validation trials across multiple vertical industries, targeting the healthcare, aquaculture and transport sectors. Healthcare, aquaculture and transport are important industry sectors in Europe, in terms of jobs, market size and international trade. Moreover, they are also vital from a social perspective, e.g., for better patient treatment, more sustainable food production and safer road transport.

The needs and requirements of vertical industries are the key drivers for the next generation wireless mobile telecommunications technology. There are also huge challenges for the network and connectivity, especially concerning latency, reliability, throughput (peak data rate) and connection density. The 5G validation trials focus on 5G applications in the three vertical industries especially for improving utility, efficient processes, and safety. It defines vital vertical use cases of healthcare, aquaculture and transport respectively by using the fifth generation wireless mobile telecommunications technology. The project investigates architecture and approaches for the validation of the trials of the three vertical industries from both technological and business perspectives. In addition, it explores business opportunities for future 5G applications in healthcare, aquaculture and transport industries, as well as a European 5G vision of "5G empowering vertical industries". It is challenging to get the 5G vision closer to deployment with innovative digital use cases involving cross industry partnerships. It requires technological and business validation of 5G end-to-end connectivity and associated management from two perspectives: i) within the set of specific requirements from one application domain; ii) across all sets of heterogeneous requirements stemming from concurrent uses of network resources by different vertical domains. [1]

The project intends to address how 5G may empower the healthcare, transport and aquaculture industries. These three vertical industries and related connectivity use cases pose diverse technical requirements on (wireless) network connectivity. These focus on validation of eMBB (enhanced Mobile Broadband), URLLC (Ultra Reliable Low Latency Communications) and mMTC (massive Machine Type Communications) services. The concept of advanced eMBB, URLLC and mMTC technological solutions for 5G validation across multiple vertical industries is illustrated in Fig. 1.


Figure 1. An ecosystem for 5G validation across multiple vertical industries [1]

In the healthcare area, the research will validate: pillcams for automatic detection in screening of colon cancer; vital-sign patches with advanced geo-localization; and 5G AR/VR paramedic services. Regarding aquaculture, it will focus on 5G-based transformation. In the transport sector, the research will focus on validation of automated/assisted/remote driving and vehicle data services [2-6].

The infrastructure shared by the verticals will host important innovations: slicing as a service; resource orchestration in access/core and cloud/edge segments with live user environments. Novel applications and devices (e.g. underwater drones, car components, healthcare devices) will be devised. Trials will run on sites of 5G-Vinni (Oslo), 5Genesis (Surrey) and 5G-EVE (Athens), and on the 5G-HEART sites (Oulu and Groningen). The trials will be integrated to form a powerful and sustainable platform where slice concurrency will be validated at scale. An overall approach and main elements are presented in Fig. 2.


5G offers the potential of a converged network infrastructure serving various use cases of multiple vertical industries (see Table 1). Cross-domain orchestration and management solutions will be developed and used to efficiently manage and execute trials, which involve simultaneous support of multiple use case scenarios from different verticals, over a given testbed/5G facility in Europe.

Table 1 - Use cases of multiple vertical industries

  Healthcare use cases

  Transport use cases

  Aquaculture use case

H1: Remote interventional support.

H2: The PillCam.

H3: Vital-sign patches with advanced
geo-localization capabilities.

  T1: Platooning.

  T2: Autonomous / Assisted driving.

  T3: Support for Remote Driving.

  T4: Vehicle Data Services.

   A1: Remote monitoring of water
   and fish quality. 


The project will provide showcases of how a single network infrastructure may be able to serve both eMBB, mMTC and URLLC services belonging to different verticals, which have completely different associated requirements, in a cost-effective manner. Further, we envisage that, for larger impact of the project, the technical solutions developed in this project could also be applicable for other 5G use cases with the same or similar technical requirements. The project contributes to the overall strategy and roadmaps of 5G PPP. It focuses on the most important use cases and handling their respective requirements, as well as the associated technical challenges for the provision of high user throughput (for eMBB), high connection density (mMTC) and high-reliable, low-latency (URLCC) communications.

5G is considered to be the ultimate converged network. The road to 5G is gradual (and expected to be long). Moving beyond the core network (mentioned above), in the current access and application layer infrastructure, there is less "convergence" in today’s telecom networks. Most 2G and 3G networks are separate from 4G/LTE ones, fixed-access and IMS are usually different than mobile ones. 5G is expected to change this and allow for a higher degree of convergence.

The new radio access (specifically due to the new features like small cells, massive-MIMO and beam forming & full-duplex) is going to become the only radio access both for fixed wireless and mobile wireless access. At the same time, ubiquitous use of VoLTE/VoWiFi (in general, VoIP in both fixed and mobile networks) will drive out the TDM (i.e. GSM) based on voice / telephony. Together with the introduction of SDN / NFV and the replacement of traditional network functions into software platforms, existing telephony networks will convert into mere applications within the new converged network architecture. This convergence is happening right now with IMS and Cloud-IMS based platforms. The same is true for data and video/TV distribution networks that are now all converging into a single IP-based network platform. Individual applications all move to the cloud together with the control and management plane of the network.

The very dissimilar requirements of different services are now being satisfied with network mechanisms that are based on Quality of Service (QoS), Virtual Private Networks (VPNs) and SLA monitoring tools. KPI validation is fragmented and is service layer or network layers focused, which depend on the use cases. The 5G network envisions to converge all the above mechanism into the slicing mechanism in order to service the increasingly extremely variable requirements of the different vertical industries.

The optimal simultaneous support of eMBB, URLLC and mMTC in the 5G network is what differentiates it from existing network infrastructures. The main 5G achievement is the introduction of an all-encompassing single network that will “absorb” and evolve existing 3G and 4G networks. 5G will come at a cost but this will be offset by the expected benefits of the converged network, which are the following:

  • · Long-term savings due to a single network that serves everybody and everything.
  • · Flexibility in introducing new services and applications.
  • · Scalability in expanding.
  • · Simplicity. Even though 5G is complex, simplicity will result from the fact that it will “absorb” the existing network functionalities, in order to become the single network that serves all traffic. This will eventually simplify the architecture.


5G-HEART (5G HEalth AquacultuRe and Transport validation trials) is funded by the European Commission Horizon 2020 Research and Innovation Framework Programme, under Grant Agreement No. 857034.


  1. 5G-HEART Consortium. Description of Actions, 5G- HEART (5G HEalth AquacultuRe and Transport validation trials). 5G-HEARTConsortium, Brussels, 2019 (restricted)
  2. 5G Automotive Association, "The Case for Cellular V2X for Safety and Cooperative Driving", white paper (undated, apparently 23 November 2016) (available from:
  3. Wevers, K., Lu, M. V2X Communication for ITS - from IEEE 802.11p towards 5G. IEEE 5G Tech Focus, 1(2). IEEE Future Networks Initiative - Enabling 5G and beyond, 2017.
  4. National Highway Traffic Safety Administration (NHTSA), Department of Transportation (DOT), "Federal Motor Vehicle Safety Standards; V2V Communications", Notice of Proposed Rulemaking (NPRM), NHTSA-2016-0126, draft version of 13 December 2016.
  5. European Commission, "A European strategy on Cooperative Intelligent Transport Systems, a milestone towards cooperative, connected and automated mobility", Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions, COM(2016) 766 final, 30 November 2016.
  6. Lu, M. (Ed.) Cooperative Intelligent Transport Systems: Towards High-Level Automated Driving. IET (Institution of Engineering and Technology), London, 2019. (in press)


KimHaesikDr. Meng Lu, Strategic Innovation Manager at Dynniq, The Netherlands; VP, IEEE Intelligent Transportation Systems Society (ITSS); Co-Chair WG Industry Engagement, IEEE Future Networks - Enabling 5G and Beyond; Member of the Editorial Board of IET (Institution of Engineering and Technology) Intelligent Transport Systems; In 2011-2015 Programme Manager at Dutch Institute of Advanced Logistics, The Netherlands; In 2009-2010 Visiting Professor at the National Laboratory for Automotive Safety and Energy, Tsinghua University, P.R. China. Since 2002 active in the areas of ICT-based ITS and logistics. Participation in European initiatives and projects since 2005, as Coordinator, WP Leader and/or Partner.

Education: PhD at LTH (Faculty of Engineering), Lund University, Sweden; Master's title and degree of Engineering in The Netherlands and P.R. China.


KimHaesikDr. Haesik Kim is Senior Scientist of the 5G-and-beyond network team in VTT Technical Research Centre of Finland. He received a M.Sc degree  from the Korea Advanced Institute of Science and Technology (KAIST), South Korea, in 2000, and and a Ph.D. degree from Lancaster University, UK, in 2009. He was visiting researcher in National Institute of Information and Communications (NICT) Japan. From 2002 to 2006, he was with Samsung Advanced Institute of Technology (SAIT) where he focused on physical layer system design and standardisation in 3G, SDR and UWB project. From 2008 to 2009, he was with NEC UK where he was involved in 4G WiMAX system design and standardisation. His current research interests include PHY and MAC layer system design, advanced coding theory, advanced MIMO, multi-carrier system, interference mitigation techniques, resource allocation schemes, machine-type communications, ultra-reliable low latency communications.

Editor: Haijun Zhang    

Haijun Zhang is currently a Full Professor in University of Science and Technology Beijing, China. He was a Postdoctoral Research Fellow in Department of Electrical and Computer Engineering, the University of British Columbia (UBC), Vancouver Campus, Canada. He received his Ph.D. degree in Beijing University of Posts Telecommunications (BUPT). From 2011 to 2012, he visited Centre for Telecommunications Research, King's College London, London, UK, as a Visiting Research Associate. Dr. Zhang has published more than 80 papers and authored 2 books. He serves as Editor of Journal of Network and Computer Applications, Wireless Networks, Telecommunication Systems, and KSII Transactions on Internet and Information Systems, and serves/served as a leading Guest Editor for IEEE Communications Magazine, IEEE Transactions on Emerging Topics in Computing and ACM/Springer Mobile Networks & Applications. He serves/served as General Co-Chair of 5GWN'17 and 6th International Conference on Game Theory for Networks (GameNets'16), Track Chair of 15th IEEE International Conference on Scalable Computing and Communications (ScalCom2015), Symposium Chair of the GameNets'14, and Co-Chair of Workshop on 5G Ultra Dense Networks in ICC 2017. His current research interests include 5G, Small Cells, Ultra-Dense Networks, LTE-U and Network Slicing.


Gee-Kung Chang, You-Wei Chen, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, and Jeff Finkelstein, Cox Communications, Atlanta, GA

IEEE 5G Tech Focus: Volume 3, Number 2, September 2019


To make the performance goals of 5G a reality, New Radio Access Network Architecture based on Fiber-Wireless Integration and Networking (FiWIN) is essential in serving diverse user scenarios, which require high wireless throughput, extremely low-latency, ultra-reliability and seamless multi-device connectivity. This paper reveals some of grand challenges in 5G mobile fronthaul and the enabling radio access technologies as well as the research breakthroughs for heterogeneous mobile data communications.

1. Introduction

To date, there is a tremendous traffic growth in mobile applications, e.g., high data rate enhanced mobile broadband (eMBB), virtual reality/augmented reality (VR/AR) wearables, industrial internet of thing (I-IoT), intelligent transport systems (ITS) and vehicle-to-everything (V2X) communication, that motivates researchers to explore research scopes defined by 5G standards and beyond in its system data throughput and network diversity. To deliver the required data seamlessly from a cloud data center to wireless subscribers, a 3G/4G/5G co-existence and heterogeneous radio access in conjunction with a fiber-based mobile fronthaul design is extremely important. The mobile fronthaul architecture gradually migrates form the legacy distributed system to the hoteling and pooling of the base band units (BBUs) system, and currently toward the centralized signal processing in the central units (CUs) and distributed units (DUs). The centralized management enables many beneficial properties for 5G network, including the higher spectral efficiency radio-over-fiber (RoF) transmission, coordinated multi-point (CoMP) data delivery, dense deployment of simplified remote radio units (RRUs) and AI optimized networking, etc. On the other hand, to economically facilitate the small cell densification, using the existing cable infrastructure in a hybrid fiber coaxial (HFC) architecture can save the construction and civil works cost, since there is already 93% broadband access had coverage by cable in the United States [1]. In this paper, we will focus on and highlight some of the key enabling radio access technologies and our recent research achievements for 5G heterogeneous fiber-wireless integration data communications, including 5G new radio (NR), signal formats, all-spectrum heterogeneous network, visible light communication (VLC) based positioning and millimeter wave (MMW) beamforming, as shown in Fig. 1.


Figure 1. Key enabling radio access technologies for 5G heterogeneous wireless data communications.

2. 5G-NRs

Due to the rapid increment of wireless data demand, the currently available low frequency wireless spectrum (sub 6GHz) is overcrowded and thus operators can leverage NR (new radio) above 24-GHz MMW frequency bands to offload data from legacy 3G/4G macro cell and relieve the network traffic congestion. 5G-NR has an abundance of spectrum and natively smaller RRU coverage, which results a higher spatial reuse network design and a limited inter-cell interference. In 3GPP Ref.15, the 5G-NR up to 52.6 GHz is standardized, while frequency ranges from 52.6 GHz to 114 GHz are extensively discussed for 5G beyond network. However, it is not a straightforward migration for NRs, some key radio access technologies (RATs) need to be further investigated and discussed in the following content.

3. Signal Waveform Designs for 5G-NR

A debate of multi-carrier or single-carrier data delivery is never dismissed. Family of multi-carrier signal formats, e.g., orthogonal frequency division multiplexing (OFDM) and filter bank multi-carrier (FBMC), have various benefits. By de-multiplexing a high-speed data stream into several narrow-band signals and parallelly transmitting them over orthogonal subcarriers, such manipulation enables a reduced inter-symbol interference (ISI) and a simplified one-tap frequency domain equalizer. Moreover, if the transmitted channel is relatively static and the transmitter knows the channel information, an adaptive power- and bit-loading could be applied among each subcarrier to maximize the channel capacity. However, the main drawback of the multi-carrier signal is its high peak-to-average power ratio (PAPR), which makes the RF power amplifier (PA) design challenging in PA linearity and leading a power back-off, especially for higher RF frequencies of 5G-NRs.

On the other hand, the multipath effect is non-significant for 5G-NR frequency channels, and most application scenarios are mainly relying on the line-of-sight (LoS) transmission, which means the channel response is relatively flat. Therefore, single-carrier signal format or DFT-spread-OFDM (DFT-s-OFDM) with lower PAPR are considered as the promising waveforms. The world record single carrier wireless data delivery of a photonics-aided MMW carrying single-carrier 64-QAM and over 1 Tb/s at D-band was experimentally demonstrated and transmitted over 3.1m wireless distance [2].

Beside the aforementioned signal formats, non-orthogonal multiple access (NOMA) [3] technology is widely discussed in the standard body for further increasing the available subscriber number. Via allocating the multiple access signature in the power domain (PD), distinct users can share the same resource element (i.e., time or frequency) and be separated at the receiver-side. Therefore, with additional PD resource, a 3D resource allocation is achieved with a finer granularity than 3G/4G network. However, conventional successive interference cancellation would inevitably induce latency and error propagation issues for users in the worse channel condition. A deep neural network (DNN) empowered bi-directional PD-NOMA in optical access network was demonstrated, and it can individually identify each users’ multiple access signature and decode all the users data simultaneously [4].

4. All-spectrum Heterogeneous Radio Access Technologies

Given that abundant NR spectra are introduced in 5G, a compatible mobile fronthaul is needed to get benefits from 3G/4G or HFC networks and facilitate 5G implementation. As the delivering RF carrier becomes higher, the 5G cell will become smaller, and thus a huge amount of wired fronthaul may be distributed for supporting the wideband radio data delivery. In the case that wired fronthaul is presently unavailable or too expensive in capital expenditure, e.g., in urban area or in disaster area, a heterogeneous fiber-wireless integration network can offer an alternative approach to achieve a Gbps-class ubiquitous-connectivity. However, the weather condition is one of the issues for the wireless MMW relay. To overcome such bottleneck, a weather-proof design by MMW/ free space optics (FSO) architecture was introduced in a mobile fronthaul [5] through the mutually complementary channel response. A hybrid transmission with adaptive diversity combining technique (ADCT) was demonstrated with 4-Gb/s OFDM to build a high-reliability wireless connection under fog, rain, and turbulence conditions.

Without considering the poor weather conditions, even in a sunny day, the blocking is another fundamental issue for LoS 5G-NR transmission, which causes wireless service interruption. With the help of the dense deployment of the 5G small cells, it is natural to assemble multiple cells for conducting a multi-connectivity transmission of 5G-NRs. A reconfigurable multiple-input multiple-output (MIMO) MMW mobile fronthaul [6] was demonstrated with enhanced path diversity, non-LoS tolerance, and infrastructure utilization as compared to the conventional single-input single-output system. The results reveal that a multi-point multi-section mobile fronthaul with dual RRUs connection can greatly extend its wireless transmission distance by 22% and enhance its tolerance of antenna misalignment by 76%.

Although the mutli-connectivity design could enhance the network reliability, the inter-cell interference (ICI) may degrade the received performance without an appropriate and reasonable control mechanism. A CoMP technology is needed to synchronize adjacent cells in the time and frequency domain. A centralized management of CU and DU could deliver the control signal through a low frequency microcell to provide frequency handover and synchronization of small cells. Therefore, the mobility and connectivity in the 5G-NR networks can be enhanced and provide the diverse services on the fly through the small cells. However, in an urban area, the available space for the small cell deployments would be limited and irregular, and thus it complicates the time discrepancy among RRUs, which increases the difficulty of synchronization. A complex-valued artificial neural network (ANN) was firstly proposed to address this issue, and it enhances the centralized network design for the MIMO 5G-NR mobile fronthaul [7]. Three time increment/improvement of time discrepancy tolerance was achieved as compared to the traditional MIMO scheme.

5. Positioning and MMW Beamforming

Since the 5G-NR poses to go to higher RF carrier frequency, the propagation loss would generally increase. Thus, a phase array antenna with large array size must be employed in both the transmitter and receiver sides for compensating the path loss, leading to eventually a “pencil-like” beam-width property and a higher spatial resolution. Because of the narrow beam-width, a new resource for wireless data communication is introduced, which is the spatial domain as shown in Fig. 2. In contrast to the widely discussed power domain NOMA, the spatial dimension in 5G and beyond can be a fully orthogonal wireless resource aided by the advanced IC design technology of spatial selectivity [8], and each signal with relative reception angle can be decoded individually. The fast-developing technologies of MMW positioning combined with beamforming enables operators to manipulate the signal transmission in spatial selectivity for further enhancing the system throughput and minimizing the inter-cell interference as well as it can greatly increase the network flexibility via reducing the size of the resource granularity in a 4D resource allocation scheme.


Figure 2. Resource allocation for 5G and beyond; 3D/4D resource allocation enables by NOMA and MMW beamforming.

As we reported before, a heterogeneous VLC/ MMW system can benefit from the low-cost LED indoor illumination system, which provides accurate receiver location and helps to enable a fast, reconfigurable MMW beamforming link as shown in Fig. 1. A 3D VLC positioning via two-layer machine learning technique with the world record of positioning resolution of <1cm in a unit volume of 0.9x1x0.4 m3 was demonstrated for indoor applications [9]. In addition, the spatial sparsity MMW together with narrow beam characteristic provides a greater spatial resolution, which facilitates the positioning estimation via time/angle of arrival (T/AoA) information in outdoor environments.

Given the improved positioning accuracy, it can enable a high-speed data transmission allowing operators to provide new network services. In the receiver-end, a user element with beamforming receiver is necessary; it should be transparent to signal waveforms, possess widely and continuously steering angles and fast beam-tracking capability. To meet the above requirement, a 2 GHz autonomous passive beamforming array with full field-of-view (±90o) reception angles was firstly introduced in 5G fixed-wireless access network [10]. 9-Gb/s data rate was achieved after 25-km fiber transmission with the world record of beam-tracking time of <3 ms.

5. Conclusions

The driving force for realizing 5G mobile data networks is based on the diverse user scenarios, and the killer application of the first phase of 5G is high-speed and high-reliable and low-latency wireless data delivery. To fulfill such demanding requirements, emerging fiber-wireless integrated access technologies of 5G-NR, NOMA, MMW and FSO hybrid wireless transmission, coordinated MMW relay, VLC positioning, and MMW beamforming was demonstrated with proof-of-concept experiments and reviewed in this paper. The next opportunities for 5G era and beyond may align with seamless migration from legacy 3G/4G infrastructure to provide advanced 5G application and toward AI/ML-based fiber-wireless access to implement optimized and cognitive networking. In FiWIN research center, we tackle the real-world problems and address urgently demanding service requirements via combining the advantages of optical and wireless access technologies for heterogeneous mobile data communications. 


  1. CableLabs, Cable Broadband Technology Gigabit Evolution, Fall, 2016.
  2. Li, J. Yu, L. Zhao, K. Wang, W. Zhou, and J. Xiao, “1-Tb/s photonics aided vector millimeter-wave signal wireless delivery at D-band,” in Proc. OFC, San Diego, CA, USA, 2018, paper Th4D.1
  3. Lu, M. Xu, L. Cheng, J. Wang, and G.-K. Chang, "Power division non-orthogonal multiple access (NOMA) in flexible optical access with synchronized downlink/ asynchronous uplink," J. Lightw. Technol., vol. 35, no. 19, pp. 4145-4152, 2017.
  4. Zhou, S. Shen, Y.-W. Chen, J. He and G.-K. Chang, “Efficient Power-Division NOMA for Intelligent Optical Access Network Enabled by Deep Learning,” in Proc. IEEE SUM, 2019, paper WB3.3.
  5. Zhang, J. Wang, Y. Xu, M. Xu, F. Lu, L. Cheng, J. Yu, and G.-K. Chang, “Fiber–wireless integrated mobile backhaul network based on a hybrid millimeter-wave and free-space-optics architecture with an adaptive diversity combining technique,” Opt. Lett., vol. 41, no. 9, pp. 1909-1912, 2016.
  6. Cheng, F. Lu, J. Wang, M. Xu, S. Shen, and G.-K. Chang, “Millimeter-Wave Radio Bundling for Reliable Transmission in Multi-Section Fiber-Wireless Mobile Fronthaul,” in Proc. OFC, Los Angeles, CA, USA, 2017, paper W1C.2.
  7. Liu, P.-C. Peng, C.-W. Hsu, J. He, H. Tian, and G.-K. Chang, “An Artificial Neural Network MIMO Demultiplexer for Small-Cell MM-Wave RoF Coordinated Multi-Point Transmission System,” in Proc. ECOC, Rome, Italy, 2018, pp. 1-3.
  8. -Y. Huang, T. Chi, F. Wang, T.-W. Li, and H. Wang, “A 23-to-30GHz hybrid beamforming MIMO receiver array with closed-loop multistage front-end beamformers for full-FoV dynamic and autonomous unknown signal tracking and blocker rejection,” in Proc. ISSCC, San Francisco, CA, USA, 2018, pp. 68-70.
  9. He, C.-W. Hsu, Q. Zhou, M. Tang, S. Fu, D. Liu, L. Deng, and G.-K. Chang, in Proc. OFC, San Diego, CA, USA, 2019, paper Th3I.2.
  10. Tang, M.-Y. Huang, Y.-W. Chen, P.-C. Peng, H. Wang, and G.-K. Chang, “A 4-channel Beamformer for 9-Gb/s MMW 5G Fixed wireless Access over 25-km SMF with Bit-loading OFDM” in Proc. OFC, San Diego, CA, USA, 2019, paper W3J.7.


GeeKungChangGee-Kung Chang is the Georgia Research Alliance and Byers Eminent Scholar Chair Professor in Optical Networking at the School of Electrical and computer Engineering of Georgia Institute of Technology. He is currently the Director of the NSF supported I/UCRC for Fiber-Wireless Integration and Networking (FiWIN). He received his B.S. degree in Physics from the National Tsing Hua University in Taiwan and his PhD degree from University of California, Riverside. Dr. Chang devoted 23 years of services in R&D at the Bell Labs, Bellcore, and Telcordia Technologies. Prior to joining Georgia Tech, he served as Vice President and Chief Technology Strategist of OpNext, Inc. Dr. Chang has co-authored more than 600 papers on peer-reviewed professional journals and international conferences. He is a Fellow of both IEEE and OSA. 



youWeiChen1You-Wei Chen was born in 1988. He received his Ph.D. degree from the Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan, in 2016. He is now a postdoctoral researcher and a lab manager at the School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, US. His research interests include but not limited to orthogonal frequency division multiplexing (OFDM), wavelength division multiplexing (WDM), passive optical networks (PON), 5G fiber-wireless integration networks and millimeter-wave (MMW) radio-over-fiber systems.



JeffFinkelsteinJeff Finkelstein is the Executive Director of Advanced Technology at Cox Communications in Atlanta, Georgia. He has been a key member of the engineering organization at Cox since 2002 and led the team responsible for the deployment of DOCSIS technologies, from DOCSIS 1.0 to DOCSIS 3.0. He was the initial innovator of advanced technologies including Pro-Active Network Maintenance, Active Queue Management, DOCSIS 3.1, DOCSIS 4.0, and the Flexible MAC Architecture. His current responsibilities include defining the future cable network vision at Cox. Jeff has over 50 patents issued or pending.




Editor: Rod Waterhouse

Rod Waterhouse received his BEng, MS, and PhD in Electrical Engineering from the University of Queensland, Australia, in 1987, 1989 and 1994, respectively. In 1994 he joined RMIT University as a lecturer, became a Senior Lecturer in 1997 and an Associate Professor in 2002.  From 2001 – 2003 Dr Waterhouse was with the venture-backed Dorsal Networks which was later acquired by Corvis Corporation. In 2004 he co-founded Pharad, an antenna and high performance RF-over-fiber technologies company of which he is the Chief Technology Officer.  From 2003 he was also appointed as a Senior Fellow within the Department of Electrical and Electronic Engineering at the University of Melbourne.  Dr Waterhouse’s research interests include antennas, electromagnetics and microwave photonics engineering.  He has over 290 publications in these fields, including 2 books and 4 book chapters. Dr Waterhouse received the grade of IEEE Fellow for his work on printed antenna and microwave photonic technologies.  Dr Waterhouse was an Associate Editor for IEEE AP Transactions during 2003 – 2009 and he is the Member at Large for IEEE Int. Topical Meeting on Microwave Photonics since 2016.  Dr Waterhouse has been on the IEEE Photonics Society Fellow Evaluation Committee since 2013 and was a Representative of the IEEE Photonics Society for the National Photonics Initiative in 2015.  In 2000, IEEE Third Millennium Medal for ‘Outstanding Achievements and Contributions’.    

Ton Koonen, Ketemaw Mekonnen, Frans Huijskens, Zizheng Cao, and Eduward Tangdiongga, Eindhoven University of Technology, The Netherlands

IEEE Future Networks Tech Focus, Volume 3, Issue 2, September 2019


Optical wireless communication is well positioned to resolve congestion in the radio spectrum caused by the booming wireless traffic demands. Two-dimensionally steerable infrared beams can provide ultra-high capacity wireless communication to many users individually. The narrow beam size enables tight spatial re-use, hence a huge data throughput. We demonstrated an indoor system providing up to 128 beams, with a capacity up to 112 Gbit/s per beam. Its on-demand highly-localized delivery scheme yields energy-efficient operation, assures enhanced privacy, and minimizes latency. It can off-load high data-rate traffic from WiFi networks, which thus get ample room to host the numerous internet-of-things devices.

1. Introduction

We are getting ever more dependent on the Internet, both in our professional and in our daily life. We want to have access always and everywhere, to our e-mail, social networks, cloud storage, and a plethora of other services. And we do prefer this access by wireless means, as we cherish to move freely and to stay always-connected by means of smartphone, laptop, tablet computer and alike. Also the myriad of small apparatus in our direct environment (the ‘Internet of Things’) requires wireless access, for numerous machine-to-machine and machine-to-human communications. Presently, the public mobile 4G networks and local WiFi networks are trying to meet these demands; in the near future, 5G networks are coming and promise high capacity and low latency under heavy traffic loads.

Notwithstanding steady progress in radio technologies, e.g., by introducing a range of complex signal processing techniques, radio technologies are getting more and more exhausted in their quest to keep up with the staggering growth of wireless service demands. We often get only poor access, or even no access at all. Each of the antenna stations has to serve a certain area, and the many users in that area even have to share the scarce radio spectrum resources. New spectrum windows are looked for, e.g., by opening up the mm-wave and sub-TeraHertz spectrum bands, but also these can offer only limited relief. A hampering access can not only mean slower downloads and on-line games at home, but also faltering security systems such as fire alarms, failing patient monitoring systems in hospitals and elderly-care homes, malfunctioning robots in industry, collisions among autonomic driving cars, etc., and hence many possibly life-threatening risks.

2. Optical wireless communication

Cooper’s Law [1] has already stated that the key to exponential growth of wireless capacity is the creation of networks consisting of pico-cells, i.e., cells served by an antenna which are so small that the antenna has to serve only a few (or even a single) user. In order to avoid a mushrooming of antennas everywhere, with the inherent necessity of an extremely-dense (wired) backbone network to deliver the services to them, each antenna should create a multitude of pico-cells itself by sending out multiple narrow beams. Massive MIMO antenna systems using mm-waves and deploying massive amounts of antenna elements are being investigated for this.

Optical technologies par excellence can precisely address the pressing needs for opening more spectrum and creating smaller cells: the visible light spectrum from 400 to 700 nm implies no less than 320THz (!) of bandwidth, and the infrared spectrum of 1500 to 1600 nm some 12.5 THz, far more than achievable with radio techniques [2][3]. In addition, optical beamforming, e.g. by means of lenses and mirrors, can yield much smaller cells than attainable with mm-waves. High-speed optical devices for the 1500-1600 nm range are already mature and amply available as they are the workhorses for our worldwide-down-to-local fiber-optic networks. And as a bonus, infrared light beyond 1400 nm is ‘eye-safe’, implying that infrared beams are safe to use as long as their power is less than 10mW; with such power levels a link budget can be realized which easily enables more than 10Gbit/s per beam… As Einstein already stated, nothing is faster than light in vacuum (and open air), so the latency of light beam links is considerably lower than that of silica fiber links. And as there is no waveguiding mechanism in free space, the light beams also do not suffer from waveguide dispersion, so can fundamentally have even a higher bandwidth than an optical fiber.

3. Optical wireless communication by narrow infrared beams

For all the above-mentioned reasons, at Eindhoven University of Technology we pursue optical wireless communication by means of narrow infrared optical beams, so-called ‘pencil beams’ [2]. Each beam is so small that it serves a single user device, hence the user gets the full capacity of that beam, exclusively, and does not need to share it. Once he got a beam, he should not experience congestion problems. We proposed an indoor high-capacity wireless system concept as illustrated in Fig. 1. An indoor fiber network acts as the backbone, connecting the pencil beam radiating antenna (PRA) elements mounted at the ceiling of each room to the central communication controller (CCC) unit which interfaces to the outdoor access network. Each room has at least two PRA-s, in order to circumvent possible blocking of the line-of-sight to a mobile device. At the CCC, all the conditioning of the data signals and the beam-steering control is done.


Figure 1.   Indoor communication network using steered narrow optical beams

For the PRA, we developed diffractive passive modules which can steer a beam without needing a separate control line. They also do not need any moving parts and/or active electro-mechanical actuators. By means of a pair of gratings which are arranged orthogonally with respect to each other, the beam’s direction is altered in two dimensions by just changing its wavelength, as shown in Fig. 2 [2]. The optical signals carrying the data are fed to the module by means of an optical fiber, where each wavelength carrier is delivering its data to a beam in the direction specifically connected to that wavelength. Generating many beams just requires bringing many wavelength carriers to the module; scaling-up the system does not require the module itself to be changed. With other beam-steering techniques reported, such as those using MEMS mirrors or spatial light modulators (SLM-s), scaling to more beams requires the module to be scaled-up as well. Moreover, our diffractive beam-steering module concept implies that the control signal (being the wavelength) at the same time is the carrier of the data signal. In other words, the control channel is embedded in the data channel and no comprehensive bookkeeping needs to be done in order to keep them together; this can ease network management and control considerably. In the laboratory, we showed 42.8 Gbit/s transmission per beam over 2.5 meters [4].


Figure 2. Two-dimensional wavelength-tuned beam steering with a pair of crossed gratings

Next to our passive beam-steering concept building on a pair of crossed diffraction gratings, we also developed a concept with the same functionality building on an optical arrayed waveguide grating router, which is a well-known wavelength demultiplexer with a common input feeder fiber and a large number of output ports [5] . Such devices are well-known in fiber-optic networks in order to establish multi-wavelength transmission links and signal routers. In our concept, the many output fibers are arranged in a square two-dimensional fiber array, and this array is put in front of a lens with high aperture; see Fig. 3. The position of a fiber with respect to the lens determines the two-dimensional direction in which the collimated beam after the lens will go; therefore again each wavelength in the input feeder fiber is translated into a narrow beam into a specific direction. Using a high port count wavelength demultiplexer operating in the C- and L-band, we showed that 128 beams can be active simultaneously, where up to now capacities up to 112 Gbit/s per beam have been demonstrated employing PAM-4 modulation [6].



Figure 3.  2D beam steering with high port count Arrayed Waveguide Grating Router

We expanded this concept into a demonstrator setup in our laboratories [5]. We implemented a localization process too, in order to determine the position of the users’ devices and with this position information adjust the wavelengths of the tunable laser transmitters in the central controller site such that the respective beams are directed accurately to the specific user devices. We showed the simultaneous real-time transmission of two high-definition video channels each embedded in a 10 Gbit/s Ethernet stream, which were received independently by two closely spaced user units. The setup is shown in Fig. 4.


Figure 4. Laboratory setup

4. Applications

With our infrared beam-steered optical communication technology, we can provide ultra-high capacity wireless data transmission where the narrow beams can offer enhanced privacy (as the neighboring users do not get the beam, so cannot listen in) and energy-lean operation (as the beams are directed only to those places where and when needed). They can actually offer every individual the benefits of a single fiber without the need of being physically connected to a fiber.

This technology may disclose the opportunities for new highly-demanding applications such as 8K ultra-high definition wireless video streaming, real-time virtual reality gaming or training without being hampered by wires, tele-presence meetings, etc . It can offer distinct advantages in environments such as in exhibition halls with frequently changing constellations of independent booths (which do not like capacity sharing), in electromagnetic radiation-sensitive areas (such as intensive care and surgery rooms in hospitals, inside airplanes, …), in airport waiting areas near the gate (where people want to do fast downloading or other voluminous internet things before getting on board), between racks inside data centers (where it provides minimum latency, as light travels 50% faster in air than in silica fiber), etc.

5. Concluding remarks

By means of 2D-steerable narrow infrared beams, very high capacity wireless connections can be created to users individually. These connections are established on-demand, only there where and when needed; thus they are congestion-free, energy-efficient, and provide a high level of privacy as well as minimum latency. The narrow beams create very small cells, which enables tightly-packed spatial re-use and thus yields a huge data throughput of the wireless system. In our demonstrator, we can create 128 beams, and showed 112Gbit/s capacity per beam.


Our research is done in the project BROWSE – Beam-steered Reconfigurable Optical-Wireless System for Energy-efficient communication, which received funding from the European Research Council in their Advanced Investigator Grant program, and in the follow-up proof-of-concept project BROWSE+.


  2. A.M.J. Koonen, “Indoor optical wireless systems: technology, trends, and applications,” J. Lightw. Technol., vol. 36, no. 8, Apr. 2018, pp. 1459-1467. DOI 10.1109/JLT.2017.2787614.
  3. A. M. J. Koonen, “Optical wireless systems: Technology, trends and applications,” in Proc. Int. Conf. IEEE Photon. Webinar, Feb. 2018. [Online]. Available: [5]
  4. C.W. Oh, E. Tangdiongga, A.M.J. Koonen, "42.8 Gbit/s indoor optical wireless communication with 2-dimensional optical beamsteering", in Proc. OFC2015, Los Angeles, March 22-26, 2015, paper M2F.3.
  5. A.M.J. Koonen, F. Gomez-Agis, F.M. Huijskens, K.A. Mekonnen, Z. Cao, E. Tangdiongga, “High-capacity optical wireless communication using two-dimensional IR beam steering,” J. Lightw. Technol., vol. 36, no. 19, Oct. 2018, pp. 4486-4493. DOI 10.1109/JLT.2018.2834374
  6. F. Gomez-Agis, S. P. van der Heide, C. M. Okonkwo, E. Tangdiongga and A. M. J. Koonen, “112 Gbit/s transmission in a 2D beam steering AWG-based optical wireless communication system”, in Proc. ECOC2017, Göteborg, Sweden, Sept. 17-21, 2017, Paper Th.2.B.1.


koonenTon Koonen (IEEE F’07, OSA F’13) is full professor in Eindhoven University of Technology (TU/e) since 2001. Since 2004, he is chairman of the group Electro-Optical Communication Systems, and since 2012 vice-dean of the department Electrical Engineering. Since 2016, he also is Scientific Director of the Institute for Photonic Integration at TU/e. Before 2001, he worked for more than 20 years in applied research in industry, amongst others in Bell Labs - Lucent Technologies. Ton Koonen is a Bell Labs Fellow (1998), IEEE Fellow (2007), OSA Fellow (2013), and Distinguished Guest Professor of Hunan University, Changsha, China (2014). In 2011, he received an Advanced Investigator Grant of the European Research Council on optical wireless communication. His current research interests are optical fiber-supported in-building networks (including optical wireless communication techniques, radio-over-fiber techniques, and high-capacity plastic optical fiber (POF) techniques), optical access networks, and spatial division multiplexed systems.

mekonnenKetemaw Addis Mekonnen (IEEE S’15) received the B.Sc. degree in electrical engineering from Mekelle University, Ethiopia, in 2007. He received the double M.Sc. degree in the Erasmus Mundus Master on photonic networks engineering program from Scuola Superiore Sant’Anna, Italy, and Aston University, U.K., in 2013. He obtained the Ph.D. degree in Eindhoven University of Technology, The Netherlands, in 2018. His current research interests include dynamic optical routing, radio over fiber, signal processing, and optical wireless communication.



huijskensFrans Huijskens graduated in applied physics at the Technical College of Dordrecht, The Netherlands, in 1979. From 1981 to 1984, he was an Electronic Test Engineer at Siemens Gammasonics. In 1985, he joined the Electro-Optical Communications Group of Eindhoven University of Technology. He worked on passive fiber couplers, on phase- and polarization-diversity coherent systems, on demonstrator setups of optical cross-connecting and optical packet switching, and on packaging of optical integrated devices. Recently he has focused on demonstrator setups of optical wireless communication.



caoZizheng Cao (IEEE S’11, M’15) received the M.Eng. degree in telecom engineering (awarded “Outstanding thesis of master degree” of Hunan Province) from Hunan University, Changsha, China, in 2010. He received the Ph.D. degree (Cum Laude) from Eindhoven University of Technology (TU/e) in 2015. Since then he is working at TU/e, where he currently is Assistant Professor. His research interests include integrated photonics circuits, microwave photonics, advanced DSP, and optical wireless communication. He received a Graduate Student Fellowship of IEEE Photonics Society in 2014. He holds two Chinese patents and two US provisional patents.



TangdionggaEduward Tangdiongga (IEEE S’01, M’10) received the M.Sc. and Ph.D. degrees from the Eindhoven University of Technology, The Netherlands, in 1994 and 2001, respectively. In 2001, he joined COBRA Research Institute working on ultrafast optical signal processing using semiconductor devices. In 2016, he became an Associate Professor on advanced optical access and local area networks. His current research interests include passive optical networks, radio over (single mode-, multimode-, and plastic) fiber, and optical wireless communication.



Editor: Rod Waterhouse

Rod Waterhouse received his BEng, MS, and PhD in Electrical Engineering from the University of Queensland, Australia, in 1987, 1989 and 1994, respectively. In 1994 he joined RMIT University as a lecturer, became a Senior Lecturer in 1997 and an Associate Professor in 2002.  From 2001 – 2003 Dr Waterhouse was with the venture-backed Dorsal Networks which was later acquired by Corvis Corporation. In 2004 he co-founded Pharad, an antenna and high performance RF-over-fiber technologies company of which he is the Chief Technology Officer.  From 2003 he was also appointed as a Senior Fellow within the Department of Electrical and Electronic Engineering at the University of Melbourne.  Dr Waterhouse’s research interests include antennas, electromagnetics and microwave photonics engineering.  He has over 290 publications in these fields, including 2 books and 4 book chapters. Dr Waterhouse received the grade of IEEE Fellow for his work on printed antenna and microwave photonic technologies.  Dr Waterhouse was an Associate Editor for IEEE AP Transactions during 2003 – 2009 and he is the Member at Large for IEEE Int. Topical Meeting on Microwave Photonics since 2016.  Dr Waterhouse has been on the IEEE Photonics Society Fellow Evaluation Committee since 2013 and was a Representative of the IEEE Photonics Society for the National Photonics Initiative in 2015.  In 2000, IEEE Third Millennium Medal for ‘Outstanding Achievements and Contributions’.    

Tetsuya Kawanishi, Waseda University

IEEE Future Networks Tech Focus, Volume 3, Issue 3, November 2019


Various types of transmission media including optical fibers, millimeter-wave links and THz links will be required in future mobile networks to offer high-speed and low-latency wireless transmission for many terminals. To mitigate congestion of radio spectrum, traffic over microwave bands should be minimized by using seamless networks where waveforms for radio services to connect end-users are transferred over optical fibers, millimeter-waves, THz-waves, etc. This article provides overviews of the seamless networks comprised of various types of transmission media with direct signal conversion.

1. Introduction

Fifth-generation mobile network (5G) should meet the requirements of the following three use cases: 1) enhanced massive broadband (eMBB) which transfers multi-gigabyte on demand, 2) massive machine type communications (mMTC) which connects many terminals and sensors, and 3) ultra-reliable and low-latency communications (URLLC) which enables rapid feedback for mission-critical applications such as autonomous driving [1]. However, it would be rather difficult to provide services, simultaneously, for the three use cases, due to limitation of available radio spectrum, where spectral congestion is very high especially in microwave bands. Beyond 5G or sixth-generation mobile network (6G) would provide these three functions (eMBB, mMTC, and URLLC), simultaneously, by generalized seamless networks consisting of various transmission media such as optical fibers, free space optics (FSO) and high-frequency radio-waves including millimeter-wave (MMW) and THz-waves.

This article focuses on hardware for spectral congestion mitigation and latency reduction. Occupancy of spectrum in THz bands (0.1-10 THz) is low as of now [2]. Thus, we can relax the spectral congestion by using THz or MMW links instead of microwave links for connection of many terminals. THz-wave realized over 100 Gb/s high-speed wireless transmission by using wide available radio spectrum. However, the transmission distance would be shorter than a few hundred meters, due to large propagation loss in the air. Thus, many base stations (BSs) and remote antenna units (RAUs) would be required to provide wide coverage [2]. Optical fiber links are commonly used to connect BSs and RAUs. However, it would be rather difficult to connect all the BSs and RAUs only by optical fibers, because the number of BSs and RAUs should be much larger than in conventional mobile networks. Signals in different transmission media such as lightwave and THz-wave can be directly and seamlessly transferred in the seamless networks where media converters can provide low-latency signal conversion [3]. We will describe system architectures for low-latency applications.

2. THz-wave for high-speed wireless transmission

The spectral congestion in low frequency bands can be mitigated by the use of the THz region where the occupancy of the bands is not very large. If we look at the history of the radio technologies, the congestion of the developed radio spectrum such as high-frequency (HF), very-high-frequency (VHF), and ultra-high-frequency (UHF) became very severe as used commonly in communications and sensing. That implies that the congestion in the THz region would be also very severe when the THz radio links are commonly used to construct beyond 5G or 6G systems. Thus, in order to offer high-performance radio services for simultaneous realization of eMBB, mMTC and URLLC, we have to pursue the two directions: exploration of high frequency carrier and enhancement of spectral efficiency.

To measure contribution to the congestion mitigation, a figure of merit by a product of carrier frequency and spectral efficiency, (CFSE: carrier frequency spectral efficiency product) has been defined in [2]. Figures 1 and 2 show the CFSE of high-speed THz transmission experiments reported recently. If the spectral efficiency is constant, the CFSE should be proportional to the carrier frequency. However, it decreases with the carrier frequency when larger than 300 GHz, as shown in Fig. 1. It shows that precise waveform control in the THz region is not mature enough to provide multi-level modulation such as quadrature-phase-shift-keying (QPSK) and quadrature-amplitude-modulation (QAM). Figure 2 shows the CFSE for various data rates. According to this survey result, we can deduce that the THz transmission systems can provide 100 Gb/s high-speed transmission by the use of 300 GHz frequency region, without losing the spectral efficiency. Over 100Gb/s THz radio transmission is being developed by using the state-of-the-art high-speed electronics [4]. Photonic local oscillators and multi-functional THz integrated circuits will provide stable 0.3 THz (300 GHz) signal generation and detection. Traveling-wave tube amplifiers (TWTA) will offer km-range transmission [5].


Figure 1. Carrier frequency spectral efficiency product (CFSE) as a function of carrier frequency [2].


Figure 2. Carrier frequency spectral efficiency product (CFSE) as a function of data rate [2].

3. Seamless networks

Figure 3 shows a configuration of the network connecting BSs and RAUs by optical fibers and THz/MMW links [3]. A BS consists of a baseband unit (BBU) and antennas (or RAUs). The BBUs, which are connected to the backbone network through mobile backhaul (MBH), bridge digital signals over fibers and waveforms for radio-services. Mobile fronthaul (MFH) transfers the waveform to connect the BBUs and RAUs directly. Beyond 5G or 6G would require many interfaces converting signals to bridge different transmission media.


Figure 3. Networks connecting BSs and RAUs [4].

Both in the optical and radio links, digital coherent technique is commonly used to increase the spectral efficiency, where the phase of the detected signal is estimated by using digital signal processing (DSP) units. If we use the conventional optical and radio links which are bridged through baseband digital signals, many DSP units are needed both in the optical and radio parts. On the other hand, radio-over-fiber (RoF) offers radio waveform transfer over fibers, where photonic signals can be directly converted into THz-waves by using optical-to-electric (O/E) and electric-to-optical (E/O) conversion devices designed for high-speed operation up to a few hundred GHz. However, it would be rather difficult to have direct E/O or O/E conversion in THz region. Figure 4 shows a configuration of IF-over-fiber (IFoF) where the THz carrier is generated in the radio front-end (FE) unit by using a frequency multiplier. Even in RoF/IFoF-based systems, DSP would be required at the RoF transmitter (Tx) and receiver (Rx), for detection of multi-level signals or compensation of signal deformation. However, the number of required DSP units would be much smaller than in the conventional systems, so that the total latency in the RoF/IFoF based seamless network shown in Fig. 4, would be much smaller than in the conventional systems [6].


Figure 4. Seamless links with IFoF [6].

Recently, a seamless network dedicated for high-speed rail has been demonstrated by using an actively controlled RoF network as shown in Fig. 5 [7]. The RoF-based seamless network was controlled by the train location information to offer handover-free operation. The configuration shown in Fig. 5 is called “linear cell”, where lineally shaped coverage along a railway track can be formed by RAUs connected by optical fibers. Each RAU has a small linear cell whose length is a few hundred meters. The linear cell configuration can also provide high-resolution imaging which can be used for foreign-object-debris detection on airport runway surfaces, where many radar heads connected through RoF [3]. The Linear cell configuration offers 1-dimensional linearly shaped coverage, where the number of required RAUs is proportional to the coverage length. It should be noted, a lot of RAUs are required for beyond 5G or 6G applications, because 2-dimensional wide coverage is needed, where the cost of the RAUs should be much lower than in linear cell systems.


Figure 5. Linear cell high-speed transmission for high-speed rail [7].

On the other hand, recently, a very simple seamless links has been proposed to offer non-line-of-sight pedestrian detection, where a received signal from a car is directly converted into a frequency-double signal as a response from a transponder carried by a pedestrian [8]. The transponder cost would be very low, while the latency in the response should be minimized.

4. Conclusion

Seamless networks with various types of transmission media including THz wave are required to offer the three important 5G features (eMBB, mMTC and URLLC) all together by one platform. Even in THz bands, the spectrum congestion would be an important issue. We have reviewed the state-of-the-art THz transmission systems, by using the CFSE (carrier frequency spectral efficiency product) which describes contribution to the mitigation of the spectral congestion. In the seamless networks with RoF (radio-over-fiber) or IFoF (IF-over-fiber), signals in different transmission media can be directly converted to bridge the links with lightwaves and radio-waves, where the latency in DSP (digital signal processing) would be minimized.

To provide photonic and THz seamless networks, there are still many challenges in reduction of cost and power consumption of the high-speed devices. At the early stage of the deployment of the seamless networks, we can focus on the linear cell configuration dedicated for public transportation infrastructures such as railways and airports. Through such deployment, we can expect realization of low cost devices for future 2-dimensional beyond 5G or 6G networks.


  1. 5G PPP Architecture Working Group, “View on 5G architecture”.
  2. T. Kawanishi, “THz and Photonic Seamless Communications,” IEEE/OSA J. Lightwave Technol. 37, 1671-1679 (2019)
  3. T. Kawanishi, A. Kanno, H. S.C. Freire, “Wired and Wireless Links to Bridge Networks: Seamlessly Connecting Radio and Optical Technologies for 5G Networks,” IEEE Microwave Magazine, 19 (3), 102-111 (2018).
  4. Website of The Horizon 2020 EU-Japan project ThoR (“TeraHertz end-to-end wireless systems supporting ultra high data Rate applications”)
  5. K. Tsutaki, Y. Neo, H. Miura, N. Masuda, M. Yoshida, “Design of a 300 GHz Band TWT with a Folded Waveguide Fabricated by Microelectromechanical Systems,” Journal of Infrared, Millimeter, and Terahertz Waves, 37, 1166-1172 (2016)
  6. APT Report on Wired and Wireless Seamless Connections using Millimeter-Wave Radio over Fiber Technology for Resilient Access Networks, APT/ASTAP/REPT-11.
  7. A. Kanno, et al., “Field Trial of 1.5-Gbps 97-GHz Train Communication System Based on Linear Cell Radio Over Fiber Network for 240-km/h High-Speed Train,” OFC 2019 post deadline paper, Th4C.2
  8. T. Kawanishi, et al., “Simple secondary radar for non-line-of-sight pedestrian detection,” to be presented in IEEE CAMA 2019.


The research work reviewed in this paper was partially supported by the Japanese Government funding for “R&D to Expand Radio Frequency Resources” and by the MIC/SCOPE #195003004 from the Ministry of Internal Affairs and Communications, Japan. The author would like to thank Dr. Naokatsu Yamamoto and Dr. Atsushi Kanno of the National Institute of Information and Communications Technology, Japan, for their fruitful discussions. The research project described in Section 2 is funded by Horizon 2020, the European Union’s Framework Programme for Research and Innovation, under grant agreement No. 814523, and by the Commissioned Research (No. 196) of National Institute of Information and Communications Technology (NICT), Japan. This work was also partially supported by Waseda Research Institute for Science and Engineering.

kawanishiHeadshotTetsuya Kawanishi (M’06–SM’06–F’13) received his B.E., M.E., and Ph.D. degrees in electronics from Kyoto University, in 1992, 1994, and 1997, respectively. From 1994 to 1995 he was with Panasonic. During 1997 he was with the Venture Business Laboratory, Kyoto University, where he was engaged in research on electromagnetic scattering and near-field optics. In 1998 he joined the Communications Research Laboratory, (now the National Institute of Information and Communications Technology), Tokyo. During 2004 he was a visiting scholar of University of California at San Diego. Since April 2015 he has been a professor at Waseda University. His current research interests include high-speed optical modulators and RF photonics.



Editor: Rod Waterhouse

Rod Waterhouse received his BEng, MS, and PhD in Electrical Engineering from the University of Queensland, Australia, in 1987, 1989 and 1994, respectively. In 1994 he joined RMIT University as a lecturer, became a Senior Lecturer in 1997 and an Associate Professor in 2002.  From 2001 – 2003 Dr Waterhouse was with the venture-backed Dorsal Networks which was later acquired by Corvis Corporation. In 2004 he co-founded Pharad, an antenna and high performance RF-over-fiber technologies company of which he is the Chief Technology Officer.  From 2003 he was also appointed as a Senior Fellow within the Department of Electrical and Electronic Engineering at the University of Melbourne.  Dr Waterhouse’s research interests include antennas, electromagnetics and microwave photonics engineering.  He has over 290 publications in these fields, including 2 books and 4 book chapters. Dr Waterhouse received the grade of IEEE Fellow for his work on printed antenna and microwave photonic technologies.  Dr Waterhouse was an Associate Editor for IEEE AP Transactions during 2003 – 2009 and he is the Member at Large for IEEE Int. Topical Meeting on Microwave Photonics since 2016.  Dr Waterhouse has been on the IEEE Photonics Society Fellow Evaluation Committee since 2013 and was a Representative of the IEEE Photonics Society for the National Photonics Initiative in 2015.  In 2000, IEEE Third Millennium Medal for ‘Outstanding Achievements and Contributions’.    

Dushmantha N.P. Thalakotuna (IEEE Member), School of Engineering, Macquarie University, Australia, Karu P. Esselle (IEEE Fellow), School of Electrical and Data Engineering, University of Technology Sydney, Australia

IEEE Future Networks Tech Focus, Volume 3, Issue 3, November 2019


Millimeter wave frequency bands are expected to play a significant role in providing higher data rates for 5G users. One of the main drawbacks of millimeter wave spectrum is the building blockages or penetration losses (in walls or glass windows) to indoor environment. Hence 5G outdoor base stations or otherwise known as gNodeBs (gNB) can fail to provide the required capacity for indoor users unless indoor base stations are in use. Deployment of indoor base stations such as femto or pico cells and connecting them into backbone network using cables can be expensive and time consuming. Thus, an inexpensive and rapidly deployable solution that can provide excellent indoor coverage will greatly benefit indoor users as well as operators. In this paper, we present and discuss such a solution referred to hereafter as a 5G extender. The concept of operation and system level architecture of the 5G extender is discussed with a main focus on highlighting challenges associated with antenna technologies to be used in this system.

1. Introduction 

One of the main use cases for 5G is enhanced mobile broadband (eMBB). The data rates of eMBB are 100 Mbps in the downlink (DL) and 50 Mbps in the Uplink (UL) in a Dense Urban test environment [1]. eMBB is best catered by mm-wave (mmW) instead of Sub 1-GHz spectrum or 1- 6 GHz spectrum due to the wider channel size (1 GHz) allowed in mmW bands.

A range of bands from 24 GHz-86 GHz are under discussion to be harmonized internationally for 5G mmW spectrum as part of ITU WRC-2019. Despite the outcome of harmonised band, one of the key challenges yet to be addressed is how one would work around the propagation loss and building blockage at mmW frequencies. This greatly hinders the ability of 5G gNBs to provide indoor coverage and capacity at mmW frequencies.

Measurements in [2-3] reported 40dB penetration loss through tinted glasses and a 28dB penetration loss through brick at 28 GHz. Such high penetration losses indicate, communication from gNBs to an indoor environment cannot be guaranteed let alone achieving eMBB speeds of 100 Mbps, which is almost impossible. Reported penetration losses from outdoor to indoor even at 3.5 GHz spectrum exceed 10 dB [4] making it challenging for gNBs to provide indoor coverage when using 1 – 6 GHz spectrum.

It is reported over 80% of 4G services take place indoors and the numbers are to be increased for 5G services [4]. This poses a great challenge on how 5G provides indoor users a similar user experience to outdoors, because 5G gNBs alone will clearly fail to provide a seamless transition from outdoor to indoor.  Solutions include using indoor 5G base stations and/or using 5G customer premises equipment (CPE) [5]. However, these solutions may incur extended setup times due to approvals and can also be costly. In the interim, or in many cases long-term, a low cost, easy to deploy solution to address this challenge will greatly benefit users and operators both.

In this paper, we present a low-cost, rapidly deployable 5G outdoor to indoor extender that can be used to boost the indoor coverage and capacity. Such a system will facilitate the eMBB service targets to be met not only outdoors but also in indoor environments with minimum cost and setup time.

The aim of this communication is to present the concept at system level and highlight the challenges that needs to be addressed by antenna technologies to be used in such 5G extender system.

2. Concept of Operation

The concept of operation is shown in Figure 1. The 5G extender system is mounted on an outside glass panel of a window in a building although other locations are also possible. The function of the extender is to amplify and retransmit the signal from a gNB to the indoor environment in the downlink (DL). In the uplink (UL), the user signal will be amplified and retransmitted to the gNB.

To achieve the maximum advantage, the 5G extender should support both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD). FDD imposed requirements necessitate the need to meet the required 5G bandwidths in 1-6 GHz and mmW bands by the 5G extender. TDD imposed requirements will enforce a processing delay specification on the 5G extender system. The eMBB service minimum user plane latency is 4ms. Hence the 5G extender should introduce the minimum time delay during amplification and transmission, for example in the range of 2-3 ms, to meet eMBB user plane latency requirement.


Figure 1: 5G extender operating concept

Apart from aforementioned functional requirements, the next major considerations are on Space Weight and Power (SWaP) aspects. The 5G extender system needs to have a small footprint and light in weight since it is proposed to be window mounted. Small footprint will provide less visibility and less disruptions to the aesthetics and appearance of buildings when it is mounted on windows in buildings or houses. Lightweight will have less stress on glass and can provide easier mounting mechanisms. Power is required to provide the amplification for UL and DL signals.

3. System Architecture

This section describes the system level architecture for the 5G extender system. The subsystems inside the 5G extender system is shown in Figure 2. Antenna systems will provide the communication links to gNB and users. The signal conditioning subsystem will provide the required filtering and amplification. The signal conditioning function can be performed using digital or analog signal processing. While digital signal processing may provide good signal conditioning in terms of filtering, analog to digital signal conversions may introduce additional delays. Hence it is appropriate to use analog signal processing in order to meet the user plane latency requirements.

The antenna system comprises of a.) outdoor antenna system and b.) indoor antenna system. The outdoor antenna system facing outdoors will create and maintain the communication link with the gNB. The indoor antenna system facing indoors will communicate with 5G new radio (NR) user terminals. 

The antenna system should support downlink and uplink as well as spatial multiplexing. To provide a full duplex communication, simplest realization would be to use two separate (TX and RX) antennas in each outdoor and indoor antenna subsystems i.e. outdoor antenna system will have a downlink antenna and an uplink antenna. Similarly, indoor antenna system will have a downlink and an uplink antenna. This will provide a distinct downlink channel and an uplink channel enabling full duplex communication.  Spatial multiplexing is desired to increase the capacity; this can be achieved by using dual polarized (+45 and -45) antenna elements.

In the DL the base station signal is received by the outdoor antenna subsystem and then amplified and filtered before it is retransmitted from indoor antenna subsystem. The signal goes through the reverse order in the UL.


Figure 2: 5G extender subsystems


The power subsystem will provide power to signal conditioning subsystem and antenna sub system to perform amplification and beam steering respectively. Since the 5G extender is mounted outside the window, it is difficult to access a power outlet using a cable (because most building do not have power outlets outside). Hence a wireless power transfer module mounted inside the window is used for powering the 5G extender. The extender unit may include an optional rechargeable battery to maintain its function during power interruptions. Also optionally, this battery may be charged using outdoor solar panels attached to the building or emerging transparent solar cells that are integrated to window glass. In some locations, solar charging during daytime may be sufficient to run the external unit whole day and night so powering the unit from mains using wireless power transfer through glass may not be necessary at all.

4. Antenna System Challenges

The focus of this section is to understand the challenges associated with developing low cost antenna systems for the 5G extender.

Directivity and Beam steering

The outdoor antenna subsystem maintains a communication link with the gNB. A higher SNR improves the quality of the link providing higher data rates. To achieve higher SNR, high gain antennas are needed. The base station antenna gain is not at the system designers’ discretion but the outdoor antenna system can be made a directive high gain antenna. If the gNB uses beamforming or has massive MIMO capability, the link will understandably provide better SNR due to the additional gain from the base station beamforming.

In practice, the 5G base station can be in any arbitrary direction relative to the 5G extender. For example, the 5G extender could be on a window of a high rise building while the base station is at a much lower altitude and off its vertical plane (orthogonal to window) as in Figure 1. Therefore, the beam should be steerable in a large conical region to point it towards the base station that sends best signals to this 5G extender system.

The conventional high gain antennas used for mmW point to point links are horns or dishes. While such solutions are feasible, it’s important to consider aesthetics, impact on building architectural integrity, potential violation of council/local government regulations and ergonomics during installation. The outdoor antenna beam should be electrically steerable and will be steered and locked towards the base station to obtain the best possible SNR during installation. Having to do mechanical alignments can result in complex mounting solutions and high initial setup costs.

Conventional horn or dish type antennas will require mechanical movements during installation to point the beam to the base station. Also horns or dishes can be bulkier compared to planar antenna types such as patch arrays or slot arrays. Horn or dish antennas with motorized remote-control are available (e.g. motorized satellite TV dish antennas) but they are even bulkier and more expensive. These features can make it impractical to use such antennas in a low profile, light weight 5G extender system.

A patch or slot antenna array with the beam steering ability can satisfy the low profile and compactness requirements and provide a high gain due to array factor. Low profile antennas such as steerable phased arrays [6], steerable patch antenna arrays [7], steerable slot arrays [8] or beam steering dielectric resonator antennas [9] stand out as good candidates for the outdoor antenna system. While there are other low-profile steerable antennas such as those in [10-12], with features such as beam steering mechanism, scanning range and antenna size may not be optimum for using them in the outdoor antenna system.

The cost of the antenna subsystem needs to be low in order to keep the 5G extender inexpensive. The printed antennas will make the antenna cost cheaper but the cost of the antenna system is mostly driven by the steering mechanism. The antenna needs to be steered and locked only once during installation, hence using an electronically steerable solution is an overkill and will increase cost. Either a simple mechanical beam steering solution or the use of near-field metasurfaces to steer the beam [9], manually or electrically with remote control, can result in a low cost antenna system.

The indoor antenna system requirements are much lenient and needs only a wider beam to provide more coverage to the indoor environment. In theory, a beamforming array can also be used as the indoor antenna, but this would require intelligence to be built in the extender providing additional signal processing delays. The eMBB service has a 4ms latency requirement, hence for simplicity it’s desirable to have only analog processing in the 5G extender system. Therefore, a simple low profile patch antenna is a good candidate for the indoor antenna system.


Making use of the principle of decoupling between two orthogonally polarized electromagnetic waves, current (and potentially future) base station antennas use +45 and -45 slant elements to provide polarization diversity. This is used to increase the capacity in a 2 layer MIMO system. The antenna systems in the 5G extender should support the polarization diversity in order provide this capacity increase by having dual polar antenna elements. In other words, each antenna (TX/RX) in the Outdoor Antenna Subsystem should be dual polarized, with two decoupled ports for the two polarizations (+/- 45o).

Each of the outdoor antenna polarization should match the corresponding polarization of the 5G base station antenna to maximize the polarization gain and to avoid cross-interference between the two data streams with orthogonal polarizations. This should hold even for steered beams of 5G extender system. However, it is very challenging for an array antenna to maintain constant polarization (and the ability to reject cross polarization leaking into it) during beam steering.

The polarization of a conventional antenna array changes with beam steering i.e. if the array has a linear polarization in the broadside beam, it becomes more elliptical as the beam steers. As a result, +45 or -45 polarized antenna array can become vertically or horizontally or elliptical polarized when its beam is steered towards an off axis gNB, as shown in Figure 3. The gNB1 is located in broadside direction of 5G extender and the two polarizations align between the extender and the gNB. Such alignment is optimum as it minimizes the crosstalk or leakage between the two data streams. When gNB is off broadside as in gNB2 but in the same horizontal plane, the polarizations of the beam of 5G extender do not exactly align with those of the base station resulting in cross-polarization leaking into the extender and degrading capacity. In gNB3 direction, the steered beam has an elliptical polarization, and again cross-polar interference and degraded capacity will become imminent.


Figure 3: Change of polarization with beam steering

It’s important to characterize this polarization of the steered beam to understand cross polarization leakage. The legacy method is to look at the Cross Polarization Discrimination (CPD) or otherwise referred as Cross Polarization Ratio (CPR) which measures magnitude difference between the cross-polarized pattern to the co-polarized pattern. BASTA recommendations [14] followed by most leading base station manufacturers states a minimum 8 – 10 dB CPD for minimum degradation on MIMO performance for legacy base station antennas. Hence, higher CPD is desirable to improve MIMO performance. 

Figure 4 shows the CPD of a 4x4 patch array when the beam is steered from +55o to -55o in the xz plane. A very high CPD is achieved when the beam is pointing towards boresight (0o) but the CPD decreases as the beam is steered off axis. It is also interesting to note that the CPD of the array follows a very similar CPD profile to a single radiating patch element (which of course has a wider fixed beam with a peak at 0o). The slight differences in the two curves are due to the mutual coupling effects between patch elements in the array.  Therefore, when mutual coupling effects are ignored the array will have the same CPD in the steered beam direction to its base radiating element.


Figure 4: Comparison of CPD along 3D representation of CPD in a patch radiating element at 28 GHz

Figure 5 shows a 3D representation of the CPD of a radiating patch at 28 GHz. It can be seen the CPD is high only in broadside direction and CPD diminishes in all other directions. An array made from this patch element will also follow the same CPD profile when its beam is steered, irrespective of the technology used for steering.


Figure 5: 3D representation of CPD from a radiating patch element at 28 GHz


Although CPD is adapted widely in base station terminology to characterize cross polarization leakage, it does not provide direct insight into the type of polarization (i.e. linear, elliptical or circular) of the radiated electric fields. Axial ratio (AR) on the other hand provides such insights.  The higher dB values in AR represent a linear polarized wave whereas a lower dB values represent an elliptically polarized wave. Zero dB AR means a circularly polarized wave.

Similar to CPD it holds that the AR of the array follows its base element AR. Therefore, it is important for a base element to have linear polarization in all possible gNB directions in order for the array to have a linearly polarized electric field in the far field. In addition, and more importantly, that two linear polarization vectors of the extender antenna must align with the two desired (+45 or -45) polarization vectors of the gNB. More precisely, ideally the polarization vector of the linearly polarized wave radiated towards the gNB by one input of the extender antenna should align with the linear polarization vector of the wave received by the +45 input of the gNB antenna. The same is true for the other input of the extender antenna and -45 input of the gNB. In practice this means that the -45o (i.e. cross-) polarization level radiated by one input of the extender antenna towards the gNB should be at least 20dB (or whatever the threshold set during network planning) weaker than the +45o (i.e. co-) polarization radiated by the same input towards the gNB for all possible directions of gNB antenna locations relative to the extender antenna. Of course, the same requirement should be met for the other input of the extender antenna as well, for -45o co-polarization.

Figure 6 shows the axial ratio (AR) and the tilt angle (ᴦ) of the polarization vector in the xz plane (Phi=0) for a typical patch antenna element at 28 GHz. It can be seen that in broadside direction (Theta=0) the AR is very high and the tilt angle is 90 degree indicating it is a vertically polarized wave. This patch antenna can be rotated about its axis by 45 degrees to receive (and transmit) one polarization of the base station antenna (say +45) while rejecting its orthogonal polarization (-45). Another patch antenna rotated in the opposite direction by 45 degrees can deal with the orthogonal (-45) polarization the same way while rejecting +45. It is possible to integrate two such orthogonally polarized elements into one dual-polarized element with two sufficiently decoupled +/- 45 outputs. The real challenge is something else. Note that away from the broad side direction the AR is decreasing making the radiated wave elliptical. At the same time the tilt angle changes meaning that polarization ellipse rotates as the beam is steered.

For the indoor antenna system, a dual-polarized radiating element (with two decoupled inputs/outputs, one for each polarization) can be used. Since there is no beamforming involved, an element with good linear polarization characteristics within the 3dB beamwidth is sufficient for the indoor antenna.





Figure 6: (a) Axial ratio in XZ plane (b) tilt angle (ᴦ) of polarization ellipse in XZ plane for the patch antenna element at 28 GHz


While 5G spectrum still needs to be harmonized, the 28 GHz and 39 GHz appear to be the most widely discussed spectra for 5G mmW communication. In 1-6GHz range, 3.5GHz spectrum is already in use for 5G at present. It is expected that 80-100 MHz in 3.5 GHz and 1GHz in mmW bands will be allocated per operator as contiguous spectrum. This requires the antenna system to support a few GHz bandwidth in the mmW bands. Hence, we require wideband antennas for both outdoor and indoor antennas in the 5G extender system.

Certain planar antenna arrays in literature have reported over 16% bandwidth at mmW frequencies [11-13], however their beam steering capability is limited. Hence more research and development are required for outdoor antenna systems that can perform wider-range beam scanning over a wide bandwidth. Maintaining sufficient polarization discrimination between the two orthogonal (desired co- and undesired cross-) polarizations when steering the beam of an array over a wide angular range is a challenge for which there is no solution at present, to the best of our knowledge. Current gNBs do have such features for electric beam tilt, but their angular range is very limited and not sufficient for this application. Although some research is in progress to address this challenge, demonstrated solutions are yet to appear in literature.

The indoor antenna system does not have stringent requirements in terms of beam steering, hence meeting a wide bandwidth will be less challenging. However, note that the indoor antenna is mounted facing towards the window. Due to close proximity, window glass may act as a near-field superstrate and has the potential to detune the antenna. Therefore, impact of glass as a superstrate should be taken into account during indoor antenna system design, which is not a challenge.

5. Conclusion

In this article, we’ve discussed a low-cost and easy to deploy 5G extender system architecture to extend coverage and capacity of gNBs to indoor users at mmW frequencies. This enables gNBs to meet its quality of service targets for eMBB service both outdoors and indoors. We also highlighted major challenges associated with antenna systems in such a 5G extender. It is shown that conventional antenna beam steering methods do not maintain antenna polarization when steering over a large angular range as required in this system (and potentially in other future 5G systems including massive MIMO arrays and large electronically-steered phase arrays at gNBs). This means that the orthogonally-polarized data stream (e.g. – 45o) will cross couple to the desired (+45o) data stream, potentially degrading significantly the signal-to-interference ratio and throughput in each channel as well as overall system capacity. Hence the outdoor antenna in such a system should not only have beam steering ability over a large angular range in both planes (elevation and azimuth relative to the antenna) but should be capable of maintaining good cross-polarization rejection when its beam is steered towards the gNB electronically or manually.

The same is likely to be an issue in future 5G base station antennas used in gNBs as well, if their beam is steered over a large angular range, as opposed to current conventional base station antennas where steering is small. This is likely to be a challenge irrespective of the scale of the gNB antenna (including MIMO or Massive MIMO) and the method of steering (e.g. digital beamforming, baseband beamforming and RF/IF beam forming) because it is a fundamental electromagnetic radiation challenge that cannot be easily resolved by digital or analog processing at the digital, baseband, IF or RF levels.


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  14. N-P-BASTA Whitepaper, Version 10.0, 17th February 2017.

ThalakotunaDushmantha Thalakotuna (M’09) received his BSc. in Electronics and Telecommunication (2008) from University of Moratuwa, Sri Lanka and PhD (2012) in Electronic Engineering from Macquarie University, Australia. He has been with Commscope Australia as a radio frequency engineer (2013-2016), BAE systems Australia as a senior radio frequency engineer (2016-2017) and Thales Australia as a senior systems engineer (2017-2019). He joined School of Engineering, Macquarie University, Australia as a lecturer in 2019. His current research interests include MMICs, Reconfigurable Microwave and Millimeter wave antennas and circuits. He is the current IEEE NSW Section secretary and is a member of Antennas and Propagation Society and Microwave Theory and Techniques Society.


EsselleKaru P. Esselle (M’92–SM’96–F’16), received the B.Sc. degree (First Class Hons.) in electronic and telecommunication engineering from the University of Moratuwa, Moratuwa, Sri Lanka, and the M.A.Sc. and Ph.D. degrees in electrical engineering from the University of Ottawa, Ottawa, ON, Canada. He has provided expert assistance to over a dozen companies,including Intel, Santa Clara, CA, USA, Hewlett Packard Laboratory, Palo Alto, CA, USA, Cisco Systems, San Jose, CA, USA, Cochlear, Sydney, Australia, Optus, Sydney, ResMed GmbH & Co. KG, Planegg, Germany, and Katherine-Werke, Rosenheim, Germany.

He is currently the Distinguished Professor of Electromagnetic & Antenna Engineering in University of Technology Sydney, Australia. Prior to this he was a Professor at Macquarie University, Sydney, Australia, a Co-Director of the WiMed Research Center, and the Past Associate Dean-Higher Degree Research of the Division of Information and Communication Sciences. He has authored over 500 research publications and his papers have been cited over 8,000 times.

Editor: Rod Waterhouse

Rod Waterhouse received his BEng, MS, and PhD in Electrical Engineering from the University of Queensland, Australia, in 1987, 1989 and 1994, respectively. In 1994 he joined RMIT University as a lecturer, became a Senior Lecturer in 1997 and an Associate Professor in 2002.  From 2001 – 2003 Dr Waterhouse was with the venture-backed Dorsal Networks which was later acquired by Corvis Corporation. In 2004 he co-founded Pharad, an antenna and high performance RF-over-fiber technologies company of which he is the Chief Technology Officer.  From 2003 he was also appointed as a Senior Fellow within the Department of Electrical and Electronic Engineering at the University of Melbourne.  Dr Waterhouse’s research interests include antennas, electromagnetics and microwave photonics engineering.  He has over 290 publications in these fields, including 2 books and 4 book chapters. Dr Waterhouse received the grade of IEEE Fellow for his work on printed antenna and microwave photonic technologies.  Dr Waterhouse was an Associate Editor for IEEE AP Transactions during 2003 – 2009 and he is the Member at Large for IEEE Int. Topical Meeting on Microwave Photonics since 2016.  Dr Waterhouse has been on the IEEE Photonics Society Fellow Evaluation Committee since 2013 and was a Representative of the IEEE Photonics Society for the National Photonics Initiative in 2015.  In 2000, IEEE Third Millennium Medal for ‘Outstanding Achievements and Contributions’.    

V. Polo, M.A. Piqueras, J. Martí, DAS Photonics, Valencia, Spain

IEEE Future Networks Tech Focus, Volume 3, Issue 3, November 2019


This paper describes photonic payloads for communication satellites employing microwave-photonics including first in-orbit demonstrations. Due to the characteristics of photonics, such as high flexibility and broad bandwidth, payloads can be designed achieving a significant size, weight and power (SWaP) reduction regarding traditional RF technologies. This combined with the intrinsic low transmission losses and latencies of photonic components and optical fibers make photonics an ideal technology for next generation fiber-in-the-space network architectures for providing 5G global coverage.

1. Introduction

5G networks and technologies are foreseen as the paradigm to satisfy the ever-increasing demand of access to digital content, driven by Internet access, video-on-demand, mobile communications and more recently, by IoT (Internet of Things). Among the different network infrastructures, the only one able to provide truly global operation, seamless access and universal coverage are satellite-based networks, either by themselves or as an extension of terrestrial networks. Until recently, satellite infrastructures were based in geostationary orbit (GEO) satellites with very wide coverage and broadband capabilities. However, their complexity has significantly increased as flexible multi-beam architectures are needed in order to be able to satisfy the new requirements of users and applications globally.  Being particularly challenging is the provision of services requiring latencies in the order of ms (milliseconds), and therefore their cost. A possible solution to this limitation are satellite mega-constellations operating at medium/low-Earth orbits (MEO/LEO), making use of GEO satellites as gateways [1], which are much more flexible, potentially cheaper and with latencies between 10 to 50 ms, compliant with 5G requirements [2]. This complex network architecture, combining GEO coverage and high-throughput with the flexibility and low-latency of LEO/MEO constellations all interconnected through RF and Optical inter-Satellite links (ISL), pushes the traditional RF and digital technologies to unprecedent performance,  SWaP and cost-effectiveness requirement levels, well beyond the today’s affordable solutions, leading to satellite manufacturers to rethink how satellites have to be built.

Photonics has emerged as an enabling technology to facilitate the implementation and deployment of such next-generation satellite network infrastructures leveraging the tremendous evolution experienced in the terrestrial domain, due to the ability of photonics to handle high data rates and RF bandwidth and its potential for large integration and mass reduction in applications such as multiple local-oscillator distribution,  antenna beamforming or multi-frequency conversion at very high frequencies, which are critical in this scenario, especially when the optical fibre is considered in the payload design substituting waveguides or coaxial cables [3-5].

2. Photonic SATCOM architectures

Figure 1 shows the sketch of a fully photonic analogue SATCOM payload. It is comprised by several key building blocks that process the incoming RF signals from the input section of the payload to the output antennas. First, the input RF signal is downconverted using broadband photonic multiple frequency converters (PMFC) which are fed by multiple LO signals coming from a photonics frequency generation unit (PFGU) [6,7] where N LO signals are externally modulated using N CW lasers and E/O modulators, whose output is multiplexed using an optical multiplexer and fed to the PMFC units.  An optical switching matrix is used to route the signals from the PMFCs to the appropriate output port. Banks of optical filters could be placed after the routing matrix either as wavelength demultiplexers or as RF-photonic channel filters. At the output of each filter, the signals are converted back to the RF domain using an Opto-electronic converter (O/E), amplified and fed to the output antenna.


Figure 1. Photonic analogue payload architecture including a multi-frequency generation unit (PFGU), optical distribution system, photonic multiple frequency conversion units (PMFC) an optical switching matrix, photonic filters and Opto-electronic converters (O/E).


Figure 2 shows the sketch of a fully photonic digital SATCOM payload, in which the capability to satisfy the requirements imposed by functionalities such as beam forming and switching, pushes significantly the digital signal processing capabilities to higher data rates. This has a direct impact on the ADC design as conversion bandwidth is limited and must be traded off with resolution. In order to overcome the limitations of the electronics/ADCs, different photonic structures have been analysed [8-11]. The incoming RF signals are directly sampled by using a Photonic ADC scheme, which allows the simultaneous sampling of a broadband spectrum, for example from 500 MHz to 40 GHz. The fundamental concept was demonstrated with 60 dBc SFDR at Ka band in an ESA research program [12], and further enhanced and demonstrated in Ka band within the FP7 project PHASER [13]. When the input signals are digitized, signal processing such as beamforming, equalisation or pre-emphasis can be made in an on-board digital processor. Once the signals are processed in the digital domain, they are then converted back to the optical domain through a Photonic DAC and then routing is performed directly in the optical domain, potentially with high-port count and fast switching speed (in the ns range).


Figure 2. Photonic digital payload architecture including photonic ADC, DAC and Beamforming functionalities.

3. Experimental validation of Key-Building blocks

Recent developments have resulted in the design, fabrication, qualification and in orbit validation of advanced microwave-photonic building-blocks, such as frequency generation and distribution units (including optical amplifiers), Ka/Q/V-band photonic-microwave downconverters and broadband photoreceivers. At a lower TRL, the demonstration of broadband tuneable photonic RF filters and beamforming networks with increasing degree of integration or photonic-assisted photonic ADC is paving the way for a fully transparent photonic payload, either for analogue, digital or hybrid architectures. The PFGU has been subject of significant work during the last decade. In [14], a PFGU was investigated and demonstrated up to TRL5. Further work has led to the design, fabrication and in-orbit-demonstration (IoD) of PFGUs combined with photonic mixers [6, 7]. Recently, in project OPTIMA [15], coordinated by AIRBUS Defense and Space, further miniaturisation has been investigated by co-packaging a distributed-feedback (DFB) laser with an external modulator chip, enabling the same functionality within a reduced size PFGU module.

Figure 3 depicts the simplified architecture of a PMFC (Photonic Multi-Frequency Converter) module. This module allows the mixing of multiple LO signals modulated onto optical carriers with an incoming RF signal in Ku/Ka/Q/V bands. The mixing occurs in a broadband optical external modulator and is replicated for all incoming wavelengths and LO frequencies coming from the LO generation unit (PFGU). Therefore, the incoming RF signal is downconverted simultaneously to several output RF frequencies than can be properly routed to the corresponding output antenna. It should be remarked that the broadband nature of the photonics technology used allows to design a frequency agnostic PMFC, limited only by the bandwidth of the external optical modulator used to perform the mixing process. Therefore, it is possible to design a photonic payload architecture in which the PMFC is universal and is interconnected to the other modules through a standard optical interface. The other module interfaces, namely the PFGU and optical receiver, must be adapted to the exact frequency bands of operation.


Figure 3  Schematic of photonic multi-frequency converter (PMFC). This concept enables the frequency conversion using multiple LOs. For the sake of simplicity, only 2 LO and 2 wavelengths are used to describe the principle of operation.

Recent work developed by DAS Photonics in collaboration with SSL (a Maxar Technologies company) has led to the demonstration of a Ka-band Flight Demonstration photonic payload aimed for payload solutions for High Throughput Satellites (HTS) systems hosted in a HISPASAT W30-6 GEO Communication satellite [6] and a V/Q Broadband Photonic Converter PFM [7] launched in EUTELSAT 7C in June 2019. The scope of the IoD included qualification level testing per specific satellite environmental requirements, comprising mechanical shock, vibration, TVAC, EMC and EMI tests. At the photonic component level, up-screening and qualification tests was carried out aiming to meet 15 year’s life for GEO orbit and ensuring no failure propagation to the interfacing elements of the satellite. This qualification comprised hermeticity, thermal cycling, mechanical shock, outgassing, Radiation TID and Protons and endurance test for the lot qualification. The PFM was subjected to vibration and TVAC tests. Functional test results have demonstrated the operation of the photonic solution and its suitability for commercial telecom satellites, especially for HTS in which a large optimization of mass, size and power consumption is foreseen respect to a traditional RF implementation. Figure 4 shows a picture of the photonic payload integrated in EUTELSAT 7C and a plot of the Q/V to Ka frequency conversion response at different input RF and LO powers. Figure 5 shows the gain compression and the noise figure of the module.


Figure 4: Pictures of the PFM including PFGU and PMFC Q/V band assemblies (left) and conversion gain to Ka at ambient temperature (+25ºC) (right).



Figure 5. Gain compression vs input RF power at different temperatures (left) and noise figure vs output frequency from V-to-Q band without input LNA (right).

Other important functions to be implemented in a photonic payload is the photonic filtering of RF signals, which exhibit more capabilities than its RF counterpart such as tunability and reconfigurability, which is of tremendous interest for future flexible telecom payloads. Within the ESA TRP contract “Photonic RF Filtering” a filter able to provide central frequency tunability and passband bandwidth adjustability suitable for its use in telecom payloads as both stand-alone RF filter or as a module to be integrated in the future optical telecom payloads was designed and manufactured. The photonic RF filter uses non-linear effects in the fiber to generate spectral regions with gain based on the Brillouin effect [16-17]. In this kind of scheme, a pump signal is injected in the same fiber where the RF signal is present, though in counter-propagating direction. Due to the Stimulated Brillouin Scattering (SBS) effect [18], a gain region is generated some GHz away from the pumping signal. The effect achieved is of active filtering, so the region to be filtered is amplified over the rest of the spectrum. SBS in optical fibers is a particularly interesting phenomenon to perform optical signal processing due to its low threshold power, narrow bandwidth and simple tuning and reconfiguration capabilities. The architecture of the Photonic RF filtering demonstrator [19-20] is shown in Figure 6 (left). The output of a continuous-wave laser is split into two branches. The lower branch is modulated by the RF input signal in an optical phase modulator to generate the Stokes signal. The upper branch is modulated in a Mach-Zehnder modulator to generate the optical pump signal, which counter-propagates then along the Stokes signal to generate Brillouin gain at the desired frequency. The filter has been implemented employing 900 m of highly non-linear fiber which exhibits an SBS frequency shift of 9.7 GHz and an SBS FWHM spectral width of < 24 MHz depending on the optical pump power. The pump modulating signal is generated employing laboratory equipment controlled by a custom graphical user interface (GUI) software. A baseband signal generated from a digital-to-analog converter (DAC) is modulated in an RF synthesizer with IQ modulation to generate a fully reconfigurable electrical pump signal. The filter bandwidth can be adjusted by modifying the number of tones as well as the frequency, amplitude, and phase of the tones of a multitoned baseband signal. The equivalent baseband response of the pump modulating signal can be digitally generated, modified and adjusted. On the other hand, the filter center frequency is adjusted by an RF synthesizer generating local oscillator (LO) frequencies of the center frequency minus the SBS frequency shift. For the SBS frequency shift of 9.7 GHz, the synthesizer should be able to be tuned within 1-3.05 GHz in order the filter gain is within the Ku-band from 10.7 to 12.75 GHz. These frequencies are relatively low and can be addressed by a synthesizer chipset for a filter stand-alone system.


Figure 6. Photonic RF filtering architecture (left) and demonstration (right).

Figure 7 (left) shows the measurements demonstrating the filter center frequency tuning in all the operational frequency range of 2 GHz for the entire Ku-band, from 10.7 to 12.75 GHz. The LO frequency is tuned from 0.907 to 3.007 GHz with 100 MHz steps. Experimentally, passband bandwidths of 36, 54 and 72 MHz where demonstrated. Insertion loss variation of 0.4 dB in-band was obtained, exhibiting better shape factor addressing sharper requirements of the filter insertion loss for higher bandwidth. In cases in which the bandwidth is close to the fundamental Brillouin bandwidth (~19 MHz) the filter shape is dominated by the fundamental response. Out-of-band rejection close to 40 dB is achieved in all the cases. Regarding group delay variation, values close to 2 ns are achieved within the filter bandwidth. Return loss was lower than -10 dB for the frequencies of interest. Figure 7 (right) shows the photonic RF filter response for 72 MHz bandwidth.


Figure 7. Photonic RF filter gain response tuning within the entire Ku-band (left) and filter response for the 72 MHz passband implementation.

4. Conclusion and Future Prospects

Photonics-enabled payloads can offer an unprecedent degree of flexibility and capacity for next generation satellite infrastructures combining LEO/MEO/GEO constellations interconnected by Optical ISL, required to satisfy the performance requirements of 5G, in particular low latencies thanks to photonics intrinsically low induced delays and switching times. The first in-orbit demonstrations of photonics payloads comprising different building blocks, such as PFGU, PMFC, optical switches and photoreceivers are a reality, demonstrating the maturity and reliability of photonics technologies, building flight heritage and paving the way for future recurrent flight models. In parallel, important advancement in the miniaturization [21-23] and qualification [24, 25] of devices and modules have been achieved. The future generation of the photonic payloads could benefit from the increased degree of miniaturization by using PIC technology, always considering that the increase in the level of integration will not jeopardize the system performance in terms of signal quality, power consumption or reliability. All in all, running programmes such as ESA Scylight HYDRON [26] of EC H2020 projects such as SODAH [27], are relying on photonics technologies as an enabler for next generation satellite communication networks able to provide 5G services.


The authors would like to acknowledge the continuous support and guidance from ESA Officers.


  1. O. Khodeli, et al., “Integration of satellites in 5G through LEO constellations”, in Proc. IEEE Glob. Comm. Conf. GLOBECOM, 2017
  2. N. Wang, et al., “Satellite Communications: what will happen after 5G?, IEEE ComSoc Technology News August 2019 (online)
  3. J. Anzalchi, P. Inigo, B. Roy, “Application of Photonics in Next Generation Telecommunication Satellites Payloads”, International Conference on Space Optics, ICSO-2014, October 2014, Tenerife, Spain.
  4. V. Polo and M.A. Piqueras, “Microwave Photonics in Space applications” (Invited), Workshop WS04 “Emerging applications of Microwave Photonics”, European Conference on Optical Communications (ECOC), Rome, 23-27 Sept. 2018
  5. M. A. Piqueras, “Microwave Photonic Applications for the Next Generation of Telecom Payloads”, International Topical Meeting on Microwave Photonics MWP 2018, 22 - 25 October 2018, Toulouse, France
  6. M.A. Piqueras, et al., “A Ka-Band Single String Photonic Payload Flight Demonstrator for Broadband High Throughput Satellite Systems and an In Orbit Demonstrator of Optical RF distribution on board satellites”,
  7. M.A. Piqueras, et al., “A Flight Demonstration Photonic Payload for up to Q/V-Band implemented in a satellite Ka-Band hosted payload aimed at Broadband High Throughput Satellites
  8. M.A. Piqueras, P. Villalba, J. Puche and J. Martí, "High Performance Photonic ADC for Space and Defence Applications", IEEE COMCAS, Tel-Aviv 2011.
  9. M.A. Piqueras et al, High-Speed, High Frequency Electro-Photonic ADC for Space enabled routers and flexible antennas”, in Proc. ICSO 2016, 18-21 October, Biarritz, France.
  10. A. Khilo et al.," Photonic ADC: overcoming the bottleneck of electronic jitter", OPTICS EXPRESS, Vol. 20, No. 4, pp. 4454-4469, 13 February
  11. Paolo Ghelfi et al., "A fully photonics-based coherent radar system", Nature 507, 341–345, March 2014.
  12. ESA contract "Electro-Photonic ADC", T516-017MM
  13. Project FP7-SPACE-2013-1, 607087 “PHASER”.
  14. ESA contract "Opto-Microwave Wideband Reconfigurable receiver", 4000102535/11/NL/NA
  15. J. Anzalchi, et. al, “Towards Demonstration of Photonic Payload for Telecom Satellites”, in Proc. ICSO 2018
  16. X.S. Yao, “Brillouin Selective Sideband Amplification of Microwave Photonic Signals,” IEEE Photon. Technol. Lett., vol. 10, no. 1, pp. 138, January 1998.
  17. B. Vidal, J.L. Corral, J. Martí, “All-optical WDM multi-tap microwave filter with flat bandpass,” Opt. Express, vol. 14, no. 2, pp. 581-586, January 2006.
  18. G. Agrawal, Nonlinear fiber optics, 5th ed., Academic Press, 2012.
  19. ESA TRP contract “Photonic RF Filtering”.
  20. M. A. Piqueras, et al., “Tunable and reconfigurable photonic RF filtering for Flexible Payloads”, in Proc. ICSO 2016, 18-21 October, Biarritz, France
  21. F. van Dijk et al, “Integrated InP Heterodyne Millimeter Wave Transmitter, IEEE Photon. Technol. Lett, 2014
  22. Micro-Opto Electronic Oscillator up to 40GHz based on LiNbO3 (OEwaves)
  23. FP7 Project 607401 “BEACON”
  24. H. Meier, “High Power Photoreceivers forHigh Dynamic Range –High Frequency Photonic RF Links”,
    ESA SATCOM final presentation days –ESA-ESTEC, 2019
  25. A. M. Joshi, S. Datta, “Space qualification of InGaAs photodiodes and photoreceivers”, in Proc. SPIE 10641, Sensors and Systems for Space Applications XI, 2 May 2018.

PoloDr Valentín Polo obtained the Ingeniero de Telecomunicaciones (MsC) and Doctor Ingeniero de Telecomunicaciones (PhD) degrees by the Universidad Politécnica de Valencia (UPV) in 1997 and 2003, respectively. Since 1997 until 2008, he worked at the Valencia Nanophotonics Technology Center at UPV, engaged in research in microwave photonics for broadband access networks. In May 2008, he moved to AIMPLAS – Polymers Technology Centre as Head of International Projects. In May 2015, he became Projects Director at DAS Photonics ( He has co-authored more than 120 papers in peer-reviewed journals and conferences in the fields of Microwave Photonics and Broadband Access Networks.



Miguel A. Piqueras received the Telecommunication Engineer and PhD degree from the Universitat Politècnica de Valencia, Spain. After five year involved in R&D activities in the Nanophotonic Technology Center (NTC), in 2006 he joined the spin-off company DAS Photonics, participating from its incubation process up to the present, now as Chief of Technology Officer. He coordinates the technical activities of the company and leads different projects in photonic integrated circuits and Microwave Photonic systems for Space and Defence applications. In parallel, he works as external expert for the European Commission.


martiProf. Javier Martí received the Ingeniero de Telecomunicación degree from the Universitat Politecnica de Catalunya (Spain) and the Doctor Ingeniero de Telecomunicación degree (Ph.D.) from the Universidad Politécnica de Valencia, (UPVLC) Spain. Since 2000 he holds a Full-Professor position at the Telecommunication Engineering Faculty in UPVLC. He is Director of the Nanophotonics Technology Centre (NTC), that includes a rapid-prototyping silicon photonics facility, in which several research activities in areas as metamaterials and plasmonics, photonic integrated devices, microwave photonics and integration of high-speed wireless-optical networks. In 2005 he founded DAS Photonics, which is pioneering the supply of advanced photonics-based solutions for Space and Electronic Warfare markets.

He has co-authored over 20 patents and more than 360 papers in refereed international technical journals in the fields of opto-microwave systems and technologies, Silicon photonics circuits and high-speed wireless-optical communications.

He has led many national and international research projects focused on photonic technology and systems and has acted the co-ordinator of many industrial consortia in the European Framework Programs (from FP5 up to FP7). He was a founder of ETP Photonics21, member of its Board of Stakeholders since the foundation as well as member of the Connect Advisory Forum at EU DG Connect.

Editor: Rod Waterhouse

Rod Waterhouse received his BEng, MS, and PhD in Electrical Engineering from the University of Queensland, Australia, in 1987, 1989 and 1994, respectively. In 1994 he joined RMIT University as a lecturer, became a Senior Lecturer in 1997 and an Associate Professor in 2002.  From 2001 – 2003 Dr Waterhouse was with the venture-backed Dorsal Networks which was later acquired by Corvis Corporation. In 2004 he co-founded Pharad, an antenna and high performance RF-over-fiber technologies company of which he is the Chief Technology Officer.  From 2003 he was also appointed as a Senior Fellow within the Department of Electrical and Electronic Engineering at the University of Melbourne.  Dr Waterhouse’s research interests include antennas, electromagnetics and microwave photonics engineering.  He has over 290 publications in these fields, including 2 books and 4 book chapters. Dr Waterhouse received the grade of IEEE Fellow for his work on printed antenna and microwave photonic technologies.  Dr Waterhouse was an Associate Editor for IEEE AP Transactions during 2003 – 2009 and he is the Member at Large for IEEE Int. Topical Meeting on Microwave Photonics since 2016.  Dr Waterhouse has been on the IEEE Photonics Society Fellow Evaluation Committee since 2013 and was a Representative of the IEEE Photonics Society for the National Photonics Initiative in 2015.  In 2000, IEEE Third Millennium Medal for ‘Outstanding Achievements and Contributions’.    


Date: 17-19 September 2019 
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The IEEE Future Networks Initiative (FNI) and IEEE Standards Association are planning an Institute-wide Future Networks Standards Forum, which will take place at the Engineering Center of the Stevens Institute of Technology, 711 Hudson St, Hoboken, NJ 07030 on 17-18 September 2019.

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  • Share key perspectives from industry, government, and academia
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9:50  Testbed  Mohammad Patwary 
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  • Complimentary daily hot breakfast buffet, 7 days a week, happy hour drinks hosted Monday through Thursday evenings
  • Free Wi-Fi and wired high-speed Internet
  • Includes secured ground/underground parking, local calls, 24-hr laundry room, fitness room and reception
  • Each person must reserve their room as soon as possible (no room block).


International Network Generations Roadmap (INGR) Leadership Team:

IEEE Future Networks Initiative Co-chairs:

  •   Ashutosh Dutta – This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Gerhard Fettweis - This email address is being protected from spambots. You need JavaScript enabled to view it. 
  •   Timothy Lee -  This email address is being protected from spambots. You need JavaScript enabled to view it.

IEEE International Network Generations Roadmap Co-chairs:

  •   Chi-Ming Chen - This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Rose Hu - This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Timothy Lee - This email address is being protected from spambots. You need JavaScript enabled to view it.
  •   Paolo Gargini - This email address is being protected from spambots. You need JavaScript enabled to view it.  

 IEEE INGR Project Manager

  •   Linda Wilson – This email address is being protected from spambots. You need JavaScript enabled to view it. 

Workshop Agenda - click to view the Agenda for the Workshop


Item  Title Speaker

IEEE 5G Initiative Overview

IEEE 5G Initiative Roadmap Classification 

Ashutosh Dutta and Gerhard Fettweis
  Roadmap Project Overview  Mischa Dohler and Chi-Ming Chen 
A What Do We Need - Verticals  
A1 5G as enabler for Medical IoT - MIS  Christoph Thuemmler
A2 Microgrid-based Power Infrastructure for Integrated Energy and Cellular Service Management Andres Kwasinski
A3 Automotive Sector Perspective  Meng Lu 
A4 Heterogeneous V2X Networks  James Irvine
A5 5G Roadmap for V2X Networks  Antonella Molinaro
B How We Do it - Radio Feature Design   
B1 IoT Wireless Security  Alenka Zajic 
B2 LiFi Attocellular Networking  Harald Haas
B3 Forward Error Correction Schemes Swapnil Mhaske and Predrag Spasojevic
B4 CMOS and BiCMOS Integrated Circuits for 5G and Beyond John Long 
B5 AP-S Antenna Perspective  Tim Lee
B6 D2D Technologies  Mohamad Ali El Hage
B7 5G Antennas and Propogation Challenges  Eric Mokole and Tapan Sarkar 
C How We Do It - Core/Service Support Design   
C1 5G Launch and Enhance EPC to Support 5G Use Cases Malla Reddy Sama
C2 5G OMEC: Proposed Mission and Roadmap  Cagatay Buyukkoc 
C3 Mobile CORD - Enable 5G on CORD Tom Tofigh
C4 5G Empowering IoT Octavia A. Dobre
C5 5G IoT Security Anand Prasad
D How to Make a Business Out of It  
D1  Micro Operators for Vertical Specfic Service Delivery in 5G Matti Latva-aho
D2 A 5G Roadmap Breakdown Structure  Adam Drobot
  Wrap up: Roadmap Workshop Brainstorming Flipcharts   






Tuesday, Oct. 23, 2018
Workshop: 8:00 a.m. - 5:30 p.m.logoni
Networking Reception: 6:00 p.m - 8:00 p.m. 

The Johns Hopkins University Applied Physics Laboratory
11100 Johns Hopkins Road, Laurel, Maryland 20723-6099
Parsons Auditorium (Lobby 1) - Campus Map and Directions

View the recordings on

View the pictures from the event.

Download the Call for Participation Flier 

Download the Agenda




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5G is not just the next evolution of 4G technology; it’s a paradigm shift. Not only is 5G evolutionary (providing higher bandwidth and lower latency than current-generation technology), more importantly, 5G is revolutionary—because it is expected to enable fundamentally new applications with much more stringent requirements in latency and bandwidth. 5G should help solve the last-mile problem and provide broadband access to the next billion users globally at much lower cost because of its use of new spectrum and its improvements in spectral efficiency.

Today, several standards organizations and forums, namely IEEE, 3GPP, and ITU, are working on defining the architecture and standardizing various aspects of 5G technologies. However, little has been studied to explore how 5G technologies can be useful to tactical and first responder networks. It is important to investigate how tactical and first responder communities can take advantage of 5G technologies to support massive bandwidth, massive sensing, and massive control type applications.

IEEE is hosting the workshop in collaboration with the JHU Applied Physics Lab. The workshop's focus is to discuss the applicability of 5G technologies for tactical and first responder networks and related opportunities and challenges. The workshop will provide a platform to bring together 5G experts from industry, academia, and the standards, regulator, and defense communities to discuss various 5G-specific use cases and requirements. The one-day event has invited speakers from DARPA, DHS, FCC, NIST, NSF, Columbia University, NYU, Intel, National Instruments, Nokia, AT&T, CERDEC, IEEE, and 3GPP. This workshop will be a catalyst to develop relevant use cases, drive standards, and investigate deployment suitable for tactical and first responder networks.

For more information, please contact Ashutosh Dutta, IEEE Future Networks Initiative Co-Chair, Johns Hopkins University. Email: This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it. Tel: 908-642-8593



Time  Speaker Affiliation Talk Title
 7:30 Registration/Breakfast    

John Forte

 JHU/APL  Welcome Address
 8:45 Ashutosh Dutta  JHU/APL APL, IEEE Future Networks Initiative Co-Chair  IEEE Future Networks Initiative Overview
 9:00 Christopher Sambar  AT&T FirstNet  Keynote  Presentation: Path to 5G & Impacts to First Responders
 9:30 Thomas Rondeau  DARPA  RF Convergence: From the Signals to the Computer 
 10:00  Break    
 10:15 Thyagarajan Nanadagopal National Science Foundation (NSF) 

Enhancing Community Response to Aid First Responders

 10:45  Henning Schulzrinne Columbia University Networks Beyond the Reach of Networks: What Roles Can 5G Play?
 11:15 David Griffith National Institute of Standards and Technology (NIST)  Modeling Device-to-Device Communications for Wireless Public Safety Networks

Manuel Uhm

 National Instruments The Next G: What does 5G mean for Critical Communications and Electromagnetic Spectrum Dominance?
 12:15 Leland Brown 
Issy Kipnis
 Intel Commercial 5G Technology as a Building Block for Tactical Wireless
 12:45 Lunch     
 1:45 Antonio DeSimone The Johns Hopkins University Applied Physics Laboratory The Special Needs of National Security and First Responder
Communications: Implications for 5G Evolution
 2:15 Robert Dew Department of Homeland Security 

5G and IoT Potential Public Safety and NS/EP Impacts

 2:45 Paul Nikolich 
Rob Fish
IEEE 802 Chair
President-Elect, IEEE Standards Association

IEEE 802 Standards - Enablers of Next Generation Networking 


 3:15 Fred Moorefield    Department of Defense   Considerations in a Brave New World of More Spectrum Sharing
 3:45 Break     
 4:00 Rapeepat Ratasuk Nokia Bell Labs  Ultra Reliable Low Latency Communication for 5G New Radio
 4:30 Julius Knapp

Federal Communications Commission (FCC)

FCC Activities to Support 5G

 5:00 Michele Zorzi University of Padova, Italy   mmWave Communications for Public Safety Applications
 5:30  Jared Everett    Closing Remarks 
 6:00  Networking Reception    


Speaker Biographies 

brown sizedLeland Brown, Techology Development Manager, Intel Federal. Leland joined the Intel Organization in 2016. Prior to Intel, Leland has 16 Years of experience in the Wireless Networking Industry for Military Applications(US Army CECOM), Commercial Cellular Wireless Network Design and Capacity Planning, Connected Device Interoperability and Wireless Technology Applications Management. Current assignment is with Intel Federal, the technology enabling organization and interface of Intel Corp for United States Government (USG) solutions. Leland’s role as Technology Development Manager (TDM) encompasses a strategic focus on investment in Advanced Wireless technology’s(5G, SDR, beamforming, Adaptive RF protocol & Adaptive Frequency) for USG applications and research opportunities.

Leland’s Initial assignment at Intel Corporation was served in the Communications and Devices Group(iCDG) supporting the pre Silicon and 3GPP adoption of 5G standards through scaling 5G technology across multiple application platforms, conducting field trail testing, device interoperability development and 5G technology demonstrations. Leland holds a BSEE from Lehigh University.

desimone sizedDr. Antonio DeSimone is the Chief Scientist for Communications Systems at Johns Hopkins University’s Applied Physics Laboratory. He is the principal technical leader for APL's efforts in National Security Communications. Prior to joining APL, he led product teams in Lucent's Optical Networking Unit and Lucent Digital Video, a pioneer in high-definition television encoding. He started his career at AT&T Bell Laboratories, where he did work in network design, performance analysis, network and computer security, wireless, digital video, and storage networking. Dr. DeSimone holds ten patents in data networking, Web caching and other Internet applications and has authored numerous technical publications. He holds Ph.D. and Sc.M. degrees from Brown University and a B.S. from Rensselaer Polytechnic Institute, all in Physics.


dew sizedRobert Dew, Senior Technologist Advisor for Emergency Communications, Office of Emergency Communications, Department of Homeland Security: Mr. Dew is responsible for overall technical advisement on design, development, testing, and deployment of priority and interoperability of Next Generation Network Priority Services (NGN-PS) including Government Emergency Telecommunications Service (GETS) and Wireless Priority Service (WPS). In addition, he is responsible for technical advisement on Next Generation 9-1-1 (NG 9-1-1), Long Term Evolution (LTE) transition to 5G and technologies for alerts, warning, and data across the Internet-of-Things (loT) for public safety and NS/EP personnel and stakeholders across the emergency communications technology landscape. He has spent over 20 years in the wireless industry working in various technical management positions developing and deploying networks for companies such as AirTouch International, Sprint-Nextel, Ericsson, Telefonica, Qualcomm, SAIC and Marconi. Mr. Dew holds a MS in Engineering Management from The George Washington University and a BS in Electrical Engineering from Virginia Tech.

fish sizedDr. Robert S. Fish is President-elect of the IEEE Standards Association and Chair of the IEEE Technical Activities Committee on Standards. Dr. Fish is a faculty member in the Department of Computer Science of Princeton University and is also President of NETovations, LLC, a consulting company focused on communications and networking innovation. From 2007 to 2010, he was Chief Product Officer and Senior VP at Mformation, Inc., a company specializing in carrier software for mobile device management. From 1997 to 2007, Rob was Vice President and Managing Director of Panasonic US R&D laboratories working on embedding networking into consumer devices. Prior to this, he was Executive Director, Multimedia Communications Research at Bellcore/Telcordia after starting his career at Bell Laboratories. He received his doctorate from Stanford University. Besides his many publications, Dr. Fish has been awarded 17 patents. For his leadership and contributions to the IEEE Communications Society’s Multimedia Communications Technical Committee, Dr. Fish was the recipient of ComSoc’s MMTC Distinguished Service Award. In 2016, for his leadership in standards activities, Dr. Fish was awarded the Standards Medallion of the IEEE Standards Association.


John Forte currently serves as the Deputy Executive for JHU/APL’s Homeland Protection Mission Area. His programs focus on securing the nation and its interests against asymmetric, terrorist-type attacks of catastrophic consequence through applied technology and systems engineering. Defeating chemical, biological, radiological, nuclear and explosive weapons as well as countering advanced persistent cyber threats is the mission area’s central challenge. John is the Mission Area’s lead in assured communications as well as in understanding and mitigating cyber threats of national importance, to include threats to state and local environments, critical infrastructure and to senior leaders and first responders. He currently serves on the Board of Advisors to Johns Hopkins University’s Information Security Institute (JHUISI) on various aspects of cybersecurity in support of their focus on research and education in information security, assurance and privacy. John also serves on the Strategic Advisory Board of SC Cyber in advising on the development of talent, techniques, and tools to defend critical, connected infrastructure within South Carolina. Further, John also serves as the Co-Director for the JHU Institute for Assured Autonomy. Conducting intelligent and autonomous systems assurance research and establishing partnerships across government, industry and academia for the safety, trust and security of the convergence of IoT, networks and infrastructure, artificial intelligence, machine learning and robotics within real-world environments.

John came to the lab after collecting valuable experience serving in senior leadership and technical positions within the US military and in the public and private sectors.

griffith sizedDr. David Griffith earned a doctorate in electrical engineering from the University of Delaware; his dissertation examined time-frequency representations of signals that are resistant to impulse noise by incorporating nonlinear filtering techniques. He spent several years in industry at various companies working on modeling satellite communications systems. At NIST, he has worked on a variety of topics, including: techniques for improving the resiliency of optical networks, including optical burst-switched networks, communications systems for smart grid, and characterizing signaling overhead in the IEEE 802.21 Media Independent Handover (MIH) protocol. He is currently working on public safety communications, including D2D communications, and on resource allocation in 5G wireless networks.


kipnis sizedIssy Kipnis is a Senior Principal Engineer who joined Intel in 2000. He is a Senior Technologist in the Communications and Devices Group. In his 30+ years in the industry he has been involved in the design and development of analog, IO, RF, sensors, storage, wired and wireless communication systems. Issy has authored or co-authored more than 60 papers, holds 14 US patents and is a Senior Member of the IEEE. Issy was born in Mexico City and holds an Ingeniero en Electrónica (BSEE) degree from the Universidad Autónoma Metropolitana, Mexico City, and a MSEE degree from the University of Michigan, Ann Arbor. His prior experience includes positions at Fairchild Camera and Instruments, Avantek, Lawrence Berkeley National Laboratory and HP/Agilent Technologies.



knapp sizedJulius Knapp has been with the FCC for 44 years and has served as the Chief of the FCC’s Office of Engineering and Technology (OET) since 2006. OET is the Commission’s primary resource for engineering expertise and provides technical support to the Chairman, Commissioners and FCC Bureaus and Offices.

He received the FCC’s Silver and Gold Medal Awards for distinguished service at the Commission as well as the Presidential Distinguished Rank Award for exceptional achievement in the career Senior Executive Service. Mr. Knapp has been the recipient of the Eugene C. Bowler award for exceptional professionalism and dedication to public service; the Federal Communications Bar Association Excellence in Government Service Award; the WCAI Government Leadership award; the National Spectrum Management Association Fellow Award; the Association of Federal Communications Consulting Engineers E. Noel Luddy Award; the Satellite Industry Association Satellite Leadership in Government Award; and, the Dynamic Spe3ctrum Alliance Lifetime Achievement Award. Mr. Knapp is a Life Member of the IEEE. He received a bachelor’s degree in electrical engineering from the City College of New York in 1974.


moorefield sizedMr. Fred Moorefield is the Acting Principal Director to the Deputy Chief Information Officer for Command, Control, Communications and Computers and Information Infrastructure Capabilities (C4IIC), Office of the Secretary of Defense, Chief Information Officer. As Principal Director, Mr. Moorefield provides technical expertise and broad guidance on policy, programmatic and technical issues relating to C4IIC to integrate and synchronize defense-wide communications and infrastructure programs. He also advises on efforts to achieve and maintain information dominance for the Department of Defense. He manages efforts defining DoD policies and strategies for design, architecture, interoperability standards, capability development and sustainment of critical command and control and communications for nuclear and non-nuclear strategic strike, integrated missile defense, Defense and National Leadership Command Capabilities, and spectrum.

Mr. Moorefield joined Federal service in 1989 in the Air Force as a civil servant, where he served for 19 years doing Research and Develop and Acquisition at Wright Patterson Air Force Base Air Force Research Labs. He also served in the Defense Information Systems Agency at the Joint Spectrum Center for four years. He has been a member of the Senior Executive Corps since 2012.

His education includes a Bachelor degree in mathematics from Wilberforce University, located in Wilberforce Ohio and a Bachelor and Master of Electrical Engineering degree from the University of Dayton in Dayton Ohio.


nandagopal sizedDr. Thyaga Nandagopal is the Deputy Division Director of the Computing and Communication Foundations (CCF) Division in the Directorate of Computer and Information Science and Engineering (CISE) at the National Science Foundation. He previously served as a Program Director at the NSF in the Networking Technologies and Systems (NeTS) program, where he managed mobile systems and wireless networking research across multiple funding programs with an annual budget of more than $50 million. At NSF, he is also leading the Platforms for Advanced Wireless Research program, a $100 million effort announced in July 2016. He also serves as the co-chair of the Wireless Spectrum Research and Development Senior Steering Group (WSRD SSG), which co-ordinates spectrum-related research and development activities across the federal government. He is an IEEE Fellow, and holds a doctorate in electrical engineering from the University of Illinois at Urbana-Champaign.


Paul Nikolich has been serving the data communications and broadband industries developing technology, standards, and intellectual property and establishing new ventures as an executive consultant and angel investor since 2001. He is an IEEE Fellow and has served as Chairman of the IEEE 802 LAN/MAN Standards Committee since 2001. As 802 Chairman he provides oversight for 75 active 802 standards and the 50+ concurrent 802 activities in wired and wireless communications networking. 802 has more than 750 active members and manages relationships between IEEE 802 and global/regional standards bodies such as ISO, ITU, ETSI, regulatory bodies and industry alliances. He is a member of the IEEE Computer Society Standards Activities Board and active leader in the IEEE, the IEEE Computer Society, and the IEEE Standards Association. He is a partner in YAS Broadband Friends LLC and holds several patents, serves on the boards of directors and technology advisory boards of companies developing emerging communications technology along with being a board member of the University of New Hampshire’s Broadband Center of Excellence. Mr. Nikolich has held technical leadership positions at large and small networking and technology companies (e.g., Broadband Access Systems, Racal-Datacom, Applitek, Motorola, Analogic). In 1978-1979 he received a bachelor's degree in electrical engineering, a bachelor's degree in biology and a master's degree in biomedical engineering from Polytechnic University in Brooklyn, NY (now the NYU Tandon School of Engineering).


ratasuk sizedDr. Rapeepat Ratasuk (This email address is being protected from spambots. You need JavaScript enabled to view it.) received a doctorate in electrical engineering from Northwestern University, Evanston, Illinois, in 2000. He is currently a Principal Research Specialist with Nokia Bell Labs, Naperville, Illinois. He has extensive experience in cellular system design and analysis, including algorithm development, performance analysis and validation, physical-layer modeling, and simulations. He has more than 70 issued patents and published more than 70 journal and conference papers. He is a co-author of the book titled "Essentials of LTE and LTE-A". His current research areas are in the areas of 5G wireless networks, mmWave, and machine-type communications.



rondeau sizedDr. Tom Rondeau joined DARPA as a program manager in the Microsystems Technology Office in May 2016. His research interests include adaptive and reconfigurable radios, improving the development cycle for new signal-processing techniques, and creating general purpose electromagnetic systems.

Prior to joining DARPA, Dr. Rondeau was the maintainer and lead developer of the GNU Radio project and a consultant on signal processing and wireless communications. He worked as a visiting researcher with the University of Pennsylvania and as an Adjunct with the IDA Center for Communications Research in Princeton, NJ.

Dr. Rondeau holds a Ph.D. in electrical engineering from Virginia Tech and won the 2007 Outstanding Dissertation Award in math, science, and engineering from the Council of Graduate Schools for his work in artificial intelligence in wireless communications.

sambar sizedChristopher Sambar, Senior Vice President, AT&T FirstNet, AT&T Business. With more than 15 years of telecommunications experience, Chris Sambar currently serves as Senior Vice President AT&T FirstNet. In this role, Chris is responsible for delivering on AT&T's commitment to successfully deploy the nation's first public safety broadband network.

Chris joined SBC Communications as part of the Leadership Development Program in 2002 with his first rotation in Network Operations as an installation and repair supervisor. Following his network assignment he held multiple sales positions in AT&T Business Solutions where he worked with C-level decision makers across various industries. Chris then moved to San Diego, California, to build various direct and indirect sales channels and coordinate the launch, marketing and sales of AT&T's U-verse television product. His success with U-verse sales led to his move to the position of Retail Director of Sales for the San Diego market area where he led all retail, door-to-door and event sales teams in the market.

Chris was then promoted to Executive Director of Retail Learning Services, Human Resources, responsible for training 40,000 retail sales people throughout the United States. Following this assignment Chris served as the Vice President and General Manager of the Virginia/West Virginia and Southern Texas markets where he was responsible for overseeing all AT&T wireline and wireless sales, service, network, marketing and public relations for the respective territories. Prior to his current role Chris was part of the Corporate Strategy Team where he assisted with the allocation of AT&T’s roughly $22 billion in annual capital spending.

Chris holds an MBA from the University of Southern California and a bachelor's degree from The United States Naval Academy. Following graduation from the Naval Academy, he served seven years on active duty and 16 years in the reserves with multiple deployments throughout Europe, the Middle East and one tour of duty during the Iraq war in 2005 and 2006. He is married with 4 children and enjoys spending as much of his free time as possible with his family.


Prof. Henning Schulzrinne, Levi Professor of Computer Science at Columbia University, received his doctorate from the University of Massachusetts in Amherst, Massachusetts. He was an MTS at AT&T Bell Laboratories and an associate department head at GMD-Fokus (Berlin), before joining the Computer Science and Electrical Engineering departments at Columbia University. He served as chair of the Department of Computer Science from 2004 to 2009, as Engineering Fellow, Technology Advisor and Chief Technology Officer at the U.S. Federal Communications Commission (FCC) from 2010 to 2017.

He has published more than 250 journal and conference papers, and more than 70 Internet RFCs. Protocols co-developed by him, such as RTP, RTSP and SIP, are used by almost all Internet telephony and multimedia applications.

He is a Fellow of the ACM and IEEE, has received the New York City Mayor's Award for Excellence in Science and Technology, the VON Pioneer Award, TCCC service award, IEEE Internet Award, IEEE Region 1 William Terry Award for Lifetime Distinguished Service to IEEE, the UMass Computer Science Outstanding Alumni recognition, and is a member of the Internet Hall of Fame.


uhm sizedManuel Uhm is the Director of Marketing at Ettus Research, a National Instruments company, the leader in Software Defined Radio platforms. Manuel has business responsibility for the Ettus USRP (GNU Radio open source-based), NI USRP (LabVIEW-based) and NI ATCA portfolios. As such, he has responsibility for SDR portfolio management including product strategy, roadmaps, and pricing. Manuel is also the Chief Marketing Officer of the Wireless Innovation Forum (formerly the SDR Forum), which is responsible for the SCA (Software Communications Architecture) standard for military radios, and CBRS (Citizen’s Broadband Radio Service) for spectrum sharing between naval radar and commercial broadband services. He has served on the Board since 2003 in various roles including Chair of the Board of Directors, Chair of the Markets Committee, Chair of the User Requirements Committee, and Chief Financial Officer.


zorzi sizedProf. Michele Zorzi, University of Padova, Italy. Michele Zorzi received his Laurea and Ph.D. degrees in electrical engineering from the University of Padova in 1990 and 1994, respectively. During academic year 1992/1993 he was on leave at the University of California San Diego (UCSD). After being affiliated with the Dipartimento di Elettronica e Informazione, Politecnico di Milano, Italy, the Center for Wireless Communications at UCSD, and the University of Ferrara, in November 2003 he joined the faculty of the Information Engineering Department of the University of Padova, where he is currently a professor. His present research interests include performance evaluation in mobile communications systems, random access in mobile radio networks, ad hoc and sensor networks and IoT, energy constrained communications protocols, 5G millimeter-wave cellular systems, and underwater communications and networking. He was Editor-in-Chief of IEEE Wireless Communications from 2003 to 2005, Editor-in-Chief of IEEE Transactions on Communications from 2008 to 2011, and is currently the founding Editor-in-Chief of IEEE Transactions on Cognitive Communications and Networking. He was Guest Editor for several Special Issues in IEEE Personal Communications, IEEE Wireless Communications, IEEE Network, and IEEE JSAC. He served as a Member-at-Large in the Board of Governors of the IEEE Communications Society from 2009 to 2011, and as its Director of Education from 2014 to 2015. He is a Fellow of the IEEE.




andrusenko sizedJulia Andrusenko (This email address is being protected from spambots. You need JavaScript enabled to view it.) received her bachelor's and master's degrees in electrical engineering in 2002 from Drexel University, Philadelphia, PA. She is a senior communications engineer at APL and is the Chief Engineer of the Tactical Wireless Systems group of APL. Ms. Andrusenko has an extensive background in communications theory, wireless networking, satellite communications, Radio Frequency (RF) propagation prediction, communications systems vulnerability, computer simulation of communications systems, evolutionary computation, genetic algorithms/programming, MIMO, and millimeter wave technologies. She also has a substantial experience developing electronic warfare methodologies for various advanced commercial communications systems and military data links. Ms. Andrusenko is a published author of many technical papers and has recently co-authored a book titled “Wireless Internetworking: Understanding Internetworking Challenges” through Wiley/IEEE Press. Ms. Andrusenko is a member of the IEEE Communications Society.


corbett sizedDr. Cherita Corbett is the Chief Scientist for the Communication and Networking Systems Group at Johns Hopkins University Applied Physics Laboratory. She guides research and development strategy and activities focused on resilient communications for military operations and critical infrastructure. Her current research interests include: secure mobile technologies, secure tactical communication systems, and insider threat protection.  Prior to joining APL, Dr. Corbett was a Senior Computer Scientist at SRI International where she performed research on self-healing cellular networks, vehicular security, and IoT security. She also provided programmatic support to the Cyber Security Division of DHS S&T in the area of mobile technology. She has published over 30 technical manuscripts and holds a U.S. patent in cyber security. She holds a Ph.D. in Electrical & Computer Engineering from Georgia Institute of Technology.


ashutosh duttaDr. Ashutosh Dutta is currently Senior Wireless Communication Research Scientist at Johns Hopkins University Applied Physics Labs (Johns Hopkins APL). Most recently he served as Principal Member of Technical Staff at AT&T Labs in Middletown, New Jersey. His career, spanning more than 30 years, includes Director of Technology Security and Lead Member of Technical Staff at AT&T, CTO of Wireless at a Cybersecurity company NIKSUN, Inc., Senior Scientist in Telcordia Research, Director of Central Research Facility at Columbia University, adjunct faculty at NJIT, and Computer Engineer with TATA Motors. He has more than 90 conference and journal publications, three book chapters, and 30 issued patents. Ashutosh is co-author of the book, titled, “Mobility Protocols and Handover Optimization: Design,Evaluation and Application,” published by IEEE and John & Wiley that has recently been translated into Chinese Language. Ashutosh served as the chair for IEEE Princeton / Central Jersey Section, Industry Relation Chair for Region 1 and MGA, Pre-University Coordinator for IEEE MGA and vice chair of Education Society Chapter of PCJS. He co-founded the IEEE STEM conference (ISEC) and helped to implement EPICS (Engineering Projects in Community Service) projects in several high schools. Ashutosh currently serves as the Director of Industry Outreach for IEEE Communications Society and is the founding co-chair for IEEE Future Networks initiative. He also serves as IEEE Communications Society’s Distinguished Lecturer for 2017-2018. He was recipient of the prestigious 2009 IEEE MGA Leadership award and 2010 IEEE-USA professional leadership award. Ashutosh obtained his BS in Electrical Engineering from NIT Rourkela, India, MS in Computer Science from NJIT, and Ph.D. in Electrical Engineering from Columbia University under the supervision of Prof. Henning Schulzrinne. Ashutosh is a senior member of IEEE and ACM.


everett sized2Jared Everett is a senior wireless communications research engineer in the Wireless Cyber Capabilities group at the Johns Hopkins University Applied Physics Laboratory (Johns Hopkins APL). Since joining APL in 2009, his research has focused broadly on the use of cellular technologies for defense and national security applications. He has a deep knowledge of LTE and emerging 5G standards, specializing in cellular air interfaces and end-to-end systems. He is a co-author of the book, “Wireless Networking: Understanding Internetworking Challenges,” published by Wiley/IEEE Press. His current research interests include innovative approaches to spectrum sharing in 5G networks. Jared holds M.S. and B.S. degrees in electrical engineering from North Carolina State University. He also holds a B.A. degree in music.


holly sizedDouglas Holly, Principle, Eagle Management Group

Doug brings a broad range of telecommunications, business leadership and management skills with a particular focus on project management, operational improvement and M&A. He currently heads up Eagle Management Group a consulting firm that provides general management, project management and strategic planning to improve operational performance. EMG also provides M&A selection, diligence support and integration services to businesses. He is a director of the Washington Section and chair its chapter of the Communications Society and also chair of the joint Washington/Northern Virginia chapter of the TEMS. He was finance chair for the IEEE GLOBECOM 2007 and 2016.

Doug holds a bachelor's and master's dress in electrical engineering from Rensselaer Polytechnic Institute.


mangra sized

Narendra Mangra is a wireless mobility advisor, consultant and educator at GlobeNet. He has over 20 years of experience consulting in the mobile satellite and cellular communications, public safety communications, information technology, higher education, and government sectors. His experience spans strategy development, spectrum management, mobile network planning and system deployments, business & operational support systems, international roaming, and wireless education. Narendra is a co-chair with the IEEE Future Networks Initiative and is an Adjunct Professor at the George Mason University. He also works with the Redhorse Corporation in assisting federal agencies with mobility and enterprise communications services modernization. His current areas of interest include smart cities and interconnected ecosystems such as public safety, connected health, smart grid, and connected vehicles.



Christina Lim, Yu Tian and Ampalavanapillai Nirmalathas, Department of Electrical and Electronic Engineering, The University of Melbourne, Australia

IEEE 5G Tech Focus: Volume 2, Number 2, May 2018


As the wireless data traffic shows no signs of slowing down, this creates a significant challenge for the next generation wireless systems with the aggregated data in the fronthaul easily exceeding the practical limits of current CPRI-based mobile fronthaul, making the capacity of the fronthaul as the key bottleneck for the next generation wireless systems. With many alternatives currently being investigated, analog transport for mobile fronthaul emerges as a simple and practical solution to address the capacity and low-latency requirements while supporting a centralized architecture.     

1. Introduction 

The wireless landscape has experienced transformational changes over the last two decades and is further shaped by the rapid growth of affordable smart portable devices with an expected number of mobile-connected devices to reach 11 billion by 2021 [1]. The next generation wireless communications (5G and beyond) adopting a centralized radio access network architecture (CRAN) is expected to support enhanced capacity, connectivity and low latency [2]. CRAN enables pooling of processing modules (baseband units (BBUs)) in a centralized location which would serve a large number of radio processing units (remote radio heads (RRHs)) in remote locations [3]. The centralized nature also enables high-level coordination functionalities such as coordinated multi-point (CoMP) transmission and massive multiple-input-multiple-output (MIMO).

Current CRAN relies on fiber-based fronthaul to provide the physical connectivity between the RRHs and BBU-pool and bases on Common Public Radio Interface (CPRI) technology [4]. CPRI uses uncompressed digitisation of the wireless signals supporting up to 12 Gb/s for use in 4G LTE-Advanced mobile systems [4]. Unfortunately current mobile CPRI fronthaul technology is not economically sustainable as it does not scale with the future wireless demands.  Such an explosion of bandwidth will create a front-haul bottleneck with CPRI style approaches only resulting in a significant wastage of optical resources. Few alternatives have recently been proposed: using data compression techniques to minimize the required fronthaul optical bandwidth [5-6], functional splits by moving more higher layer operations into the RRHs [7-9] and using analog optical transport in place of CPRI in the fronthaul links [10-18].

3rd Generation Partnership Project (3GPP) has defined eight options for functional split between the BBU and RRH [19]. High-level functional splits improves bandwidth utilization but decentralizes control functionality and increases latency while low-level splits maintains the centralization capability but increases the bandwidth utilization. There is a tradeoff between latency, throughput and centralization capavility. One example of low-level splits is eCPRI with split point within the physical layer [20].

The analog transport of the wireless signals either at an intermediate frequency (IF) or at the radio frequency (RF) over the fronthaul link emerges as a promising option with capability to overcome the issues arising from functional splits. This scheme maintains the wireless spectral bandwidth thus reducing the requirement for CPRI transmission capacity, while enabling centralized control capability with minimal latency. Despite the simplicity of analog optical transport of the wireless signals, this approach is currently not popular among network providers. The main reason being that analog signals are more prone to noise and nonlinearity impacting the dynamic range of the link. This is true for large macrocell sites that require a large dynamic range to satisfactorily service users at cell edges. Wireless infrastructure evolving towards smaller cell sizes relaxes this stringent requirement on the dynamic range. Analog transport may now emerge as a serious contender for mobile fronthaul.

2. Analog Transport of Wireless Signals 

Traditionally the concept of analog transport of wireless signals is shown in Fig. 1. The wireless signals are modulated onto an optical carrier and then distributed optically via an optical distribution network. The wireless signals are then detected using a photodetector before they are distributed wirelessly to the end users. The wireless signals can be transported at intermediate frequencies over fiber (IFoF) (Fig. 1a) or at the designated wireless frequency over fiber (RFoF) (Fig. 1b).


Figure 1:  Schematic of (a) IFoF and (b) RFoF transport schemes

RFoF transport is the simplest technique as the detection in the RRH only requires direct detection using a photodetector and does not require additional frequency translation stages. It has the advantage of realizing a small footprint RRH with full centralized control architecture. Despite the simplistic design, this scheme suffers from RF power fading due to fiber chromatic dispersion [21] and the requirement for optical devices with speeds matching that of the wireless carrier frequency which becomes more stringent for wireless signals in the millimeter-wave region.

IFoF transport overcomes the limitations of RFoF where relatively low-speed optoelectronic devices are required as the wireless signals are distributed optically at a much lower frequency and hence, has much reduced fiber chromatic dispersion effects. On the contrary, the RRH requires frequency translation stages that demand stable local oscillators and linear mixers. The complexity increases with wireless carrier frequency and may impede future network upgradability.

3. Demonstration of IFoF for 5G Fronthauls

There have been a number of reported demonstrations of IFoF for mobile fronthaul transport [10-13]. These demonstrations include the distribution of 128 x 100 MHz signals over 20 km of fronthaul link based on sub-Nyquist sampling technique [10], 32 x 200 MHz signals over 1 km of fronthaul link [11], bi-directional transmission of 20 x 80 MHz downlink signals and 16 x 80 MHz uplink signals over 25 km of fronthaul link based on carrier aggregation [12] and 60 GHz using leaky wave antenna [13]. These demonstrations focus on pushing the boundary of capacity improvement.

Ishimura et. al. has demonstrated an IFoF transport scheme that supports wideband operation and long-distance transmission by overcoming the impact of dispersion-induced RF power fading for transporting double sideband formatted wireless signals [14]. The scheme is based on a parallel intensity modulation (IM)/phase modulation (PM) transmitter that exploits the complementary relationship of the IM and PM signals response of the link. Therefore by assigning the aggregated IF signals to the appropriate modulators during electrical-to-optical conversion, the optically modulated IF signals will experience a relatively flat response over the fronthaul link thus overcoming the impact of fiber chromatic dispersion. They have demonstrated a transmission of 20 x 360 MHz orthogonal-frequency division multiplexed (OFDM) signals over 40 km of single-mode fiber (SMF) [14] and 14 x 1.2 GHz OFDM signals over 20 km of SMF [15].

Sung et. al. has demonstrated the feasibility of an IFoF transport for mobile fronthaul for 28 GHz wireless operation with real-time processing [16]. In the proposed scheme, the clock signal was simultaneously transmitted with the wireless signals in the form of an IF carrier. The clock was then used to convert the IF signals to the 28 GHz wireless signals, and hence reducing the implementation cost of the RRH. The results showed that simultaneous clock transmission resulted in performance degradation of <0.5% in error vector magnitude. A peak data rate of 1.5 Gb/s per user was demonstrated in this transmission [16].

4. Demonstration of RFoF for 5G Fronthauls

Apart from IFoF transport, there are also reported RFoF transport for mobile fronthaul targeting towards mm-wave wireless signals transmission for 5G [17-18]. Dat demonstrated the transmission of 2 x 20MHz LTE-A and 4 x 800MHz F-OFDM for 90GHz wireless transmission using dual optical carriers with photonics upconversion [17].    

Tian et. al. has demonstrated an RFoF transport scheme for the distribution of 60 GHz wireless signals in a multi-user mobile fronthaul link incorporating non-orthogonal multiple access (NOMA) scheme [18]. This highlights the centralized controlled capability of BBU pool with a proof-of-concept demonstration for a two-user scenario. Figure 2 shows the architecture of the 60 GHz RFoF fronthaul with the RRH serving two users spatially separated within the same cell – one user closer to the RRH (NU) and one user at the cell edge (FU). To ensure the far user (FU) has similar performance as the near user (NU), the centralized BBU jointly process and multiplex the signals from the two users in the power domain using NOMA scheme with significant different electrical launched power favoring the FU. Tian et. al. proposed a NOMA scheme using a novel multilevel code (MLC) scheme that ensured no error propagation from the far user to the near user, enabling more flexible power allocation ratio design at the centralized BBU [18]. A total of 8 Gb/s was demonstrated over 3 km of SMF and up to 2.5m wireless link at 60 GHz to simultaneously serve a near user located at 0.38 m and a far user at 2.5m from the RRH.


Figure 2: System architecture for 60 GHz wireless with RFoF fronthaul incorporating NOMA scheme

5. Conclusions 

CPRI-based mobile fronthaul will be a bottleneck for the next generation wireless systems. To maintain a bandwidth-efficient centralized architecture supporting latency sensitive applications, analog transport technology emerges as a potential solution for mobile fronthaul. Despite the elegance and simplicity, there are still many technical challenges including implementation cost, interoperability and compatibility, that need to be further addressed.


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  2. Framework and Overall Objectives of the Future Development of IMT for 2020 and Beyond, ITU-R M.2083, 2015.
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  5. D. Samardzija, J. Pastalan, M. MacDonald, S. Walker, and R. Valenzuela, “Compressed transport of baseband signals in radio access networks,” IEEE Trans. on Wireless Communications, vol. 11, no. 9, pp. 3216-3225, 2012.
  6. S.H. Kim, H.S. Chung, and S.M. Kim, “Experimental demonstration of CPRI data compression based on partial bit sampling for mobile front-haul link in C-RAN”, in Proc. 2016 Optical Fiber Communications Conference and Exhibition (OFC 2016), pp. 1-3, 2016.
  7. A. Maedar, M. Lalam, A.D. Domenico, E. Pateromichelakis, D. Wubben, J. Bartelt, R. Fritzsche and P. Rost, “Towards a flexible function split for cloud-RAN networks,” in Proc. of European Conference on Networks and Communications (EuCNC), 2014.
  8. N.J. Gomes, P. Chanclou, P. Turnbull, A. Magee, and V. Jungnickel, “Fronthaul evolution: from CPRI to Ethernet,” Journal of Optical Fiber Technology, vol. 26, pp. 50-58, Dec. 2015.
  9. S. Zhou, X. Liu, F. Effenberger, and J. Chao, “Mobile-PON: A high-efficiency low-latency mobile fronthaul based on functional split and TDM-PON with a unified scheduler,” in Proc. of 2017 Optical Fiber Communications Conference and Exhibition (OFC 2017), pp. 1-3, 2017.
  10. L. Cheng, X. Liu, N. Chand, F. Effenberger, and G. Chang, “Experimental demonstration of sub-Nyquist sampling for bandwidth and hardware-efficient mobile fronthaul supporting 128 x 128 MIMO with 100MHz OFDM signals”, in Proc. Optical Fiber Comm. Conference, pp. 1-3, 2015.
  11. X. Liu, H. Zeng, N. Chand, and F. Effenberger, “Efficient mobile fronthaul via DSP-based channel aggregation”, J. Lightwave Technol., vol. 34, no. 6, pp. 1556-1564, 2016.
  12. M. Xu, J. Yan, J. Zhang, F. Lu, J. Wang, L. Cheng, D. Guidotti, and G.K. Chang, “Bidirectional fiber-wireless access technology for 5G mobile spectral aggregation and cell densification”, J. Opt. Commun. Netw., vol. 8, no. 12, pp. B104-B110, 2016.
  13. U. Habib, M. Steeg, A. Stohr, and N. Gomes, “Radio-over-fiber-supported 60GHz multiuser transmission using leaky wave antenna”, Proc. Microwave Photonics (MWP), pp. 1-4, 2017.
  14. S. Ishimura, B.G. Kim, K. Tanaka, K. Nishimura, H. Kim, Y.C. Chung, and M. Suzuki, “Broadband IF-over-fiber transmission with parallel IM/PM transmitter overcoming dispersion-induced RF power fading for high-capacity mobile fronthaul links”, IEEE Photonics J., vol. 10, no. 1, 790069, 2018.
  15. S. Ishimura, A. Bekkali, K. Tanaka, K. Nishimura, and M. Suzuki, “1.032-Tb/s CPRI-equivalent rate IF-over-fiber transmission using a parallel IM/PM transmitter for high-capacity mobile fronthaul links”, J. Lightwave Technol., vol. 36, no. 8, pp.1478-1484, 2018.
  16. M. Sung, S. Cho, J. Kim, J.K. Lee, J.H. Lee, and H.S. Chung, “Demonstration of IFoF-based mobile fronthaul in 5G prototype with 28-GHz millimeter wave”, J. Lightwave Technol., vol. 36, no. 2, pp. 601-609, 2018.
  17. P.T. Dat, A. Kanno, N. Yamamoto, and T. Kawanishi, “190-Gb/s CPRI-equivalent rate fiber-wireless mobile fronthaul for simultaneous transmission of LTE-A and F-OFDM signals”, Proc. European Conference on Optical Communications (ECOC), pp. 1-3, 2016.
  18. Y. Tian, K.L. Lee, C. Lim, and A. Nirmalathas, “Demonstration of non-orthogonal multiple access scheme using multilevel coding without successive interference cancellation with 60GHz radio-over-fiber fronthaul”, in Proc. 2018 Optical Fiber Communications Conference and Exhibition (OFC 2018), paper Tu3J.4, 2018.
  19. 3GPP TR 38.801 v2.0.0 Release 14, 2017.
  20. eCPRI Specification v1.0, “Common public radio interface: eCPRI interface specification”, Aug. 2017.
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limChristina Lim received the Ph.D. degrees in Electrical and Electronic Engineering from the University of Melbourne, Australia in 2000.  She is a Professor and currently the Deputy Head of Department at the Department of Electrical and Electronic Engineering, the University of Melbourne, Australia.  She was awarded the Australian Research Council (ARC) Australian Research Fellowship from 2004-2008 and the ARC Future Fellow (2009-2013).  She was an elected member of the IEEE Photonics Society Board of Governors (2015-2017) and currently serving in the IEEE Photonics Society Conference Council. She is also a member of the Steering Committee for the IEEE Topical Meeting on Microwave Photonics Conference. She is an Associate Editor for IEEE Photonics Technology Letters and IET Electronics Letter. Her research interests include fiber-wireless access technology, modeling of optical and wireless communication systems, microwave photonics, and optical network architectures.



Yu Tian received the B.S. degree in Optoelectronic Information Engineering from Huazhong University of Science and Technology, Wuhan, China, in 2014. Since 2014, she has been working towards the Ph.D. degree in fiber wireless communications in the University of Melbourne, Melbourne, Australia. Her main research interests are primarily in the area of 60 GHz radio-over-fiber fronthaul communications with an emphasis on physical layer network implementation, coordinated multipoint transmission, non-orthogonal multiple access schemes, and system level simulation.




Thas A Nirmalathas is a Professor of Electrical and Electronic Engineering at the University of Melbourne and also Director of the Networked Society Institute – an interdisciplinary research institute focusing on challenges and opportunities arising from the society’s transition towards a networked society. Prof Nirmalathas obtained his PhD in Electrical and Electronic Engineering from the University of Melbourne. Over the past two decades, he has held many senior leadership positions at the University of Melbourne including Head of Department, Electrical and Electronic Engineering. He has also held visiting scientists appointments at NICT Japan and I2R Singapore. Thas has written more than 450 technical articles. His current research interests include energy efficient telecommunications, access networks, optical-wireless network integration and broadband systems and devices.


Editor: Rod Waterhouse


Nikola Serafimovski, pureLiFi, Ronan Lacroix, Deutsche Telecom, Micheline Perrufel, Orange, Sylvain Leroux,Orange, Simon Clement, Liberty Global, Nirlay Kundu, Verizon, Dominique Chiaroni, Nokia, Gaurav Patwardhan, Hewlett Packard Enterprise, Andrew Myles, Cisco, Christophe Jurczak, Lucibel, Marc Fleschen, Zero.1, Marty Ragusky, VLNComm, Volker Jungnickel, HHI, Dimitri Ktenas, CEA Leti, Harald Haas, University of Edinburgh

IEEE 5G Tech Focus: Volume 2, Number 2, May 2018 


Setting the Scene

We live in an increasingly connected world where the spectrum for wireless communications must service an exponentially growing demand for wireless data.

The demand for mobile communications is increasing at over 50% per year according to the Cisco Visual Networking Index. Indeed, by 2021 more than half of 17 billion connected devices will be mobile, 65% of the IP traffic will be from mobile devices, 80% of the internet traffic will be video requiring high-speed wireless at an average speed of 20 Mbps. This demand is expected to increase as the Internet of Things (IoT) becomes a reality, and the number of connected devices grows from 5 billion to over 20 billion by 2020. Indeed, in 2017 for the first time, more objects were connected than human beings on Earth, with 8.38 billion connected devices compared to 7.5 billion humans (source Gartner 2017). Unsurprisingly, in 2016, over 50% of all wireless data went through a Wi-Fi access point. Figure 1 shows the historical and predicted demand for wireless data, pointing clearly to the inevitably growing shortfall in available wireless capacity over the years.


Figure 1: Historical and predicted demand/supply for wireless data. Source:

This results in a need for a continued increase in capacity of wireless networks, which depends directly on the availability of additional unlicensed spectrum, the cost-effective deployment of the connectivity infrastructure and the increased densification of wireless access points. Indeed, over the past 60 years, the capacity of wireless networks has increased by over 1,000,000 times between 1955 and 2011, largely following Cooper’s Law where the data rate available to a wireless device doubles roughly every 30 months. It is cell densification that is responsible for over 1600 times of this growth, as shown in Figure 2.


Figure 2: Key and contributing factors to the growth of wireless capacity from 1955 until 2011. The continued growth in wireless network capacity must come from smaller cells. Graphical representation of the findings:

Despite the significant increase in cell densification, there is still a need for more spectrum. A recent study by the Wi-Fi Alliance has acknowledged the imminent need for more unlicensed spectrum, where it has identified:

  • “Between 500 MHz and 1 GHz of additional spectrum in various world regions may be needed to support expected growth in Wi-Fi by 2020;  
  • If demand for Wi-Fi exceeds expected growth, then between 1.3 GHz and 1.8 GHz more spectrum may be required by 2025; and
  • Wi-Fi spectrum needs to be sufficiently contiguous to support 160 MHz wide channels, which are required to support a growing number of bandwidth-intensive applications and to allow maximum Wi-Fi benefits to be attained.”

There are multiple solutions that can provide an increase in the available spectrum. As an example, WiGig solutions, defined in IEEE 802.11ad and being revised in IEEE 802.11ay that operate in the 60 GHz spectrum have access to around 14 GHz of bandwidth in the USA. However, WiGig and other mm-wave RF solutions all exhibit similar challenges.  First, ICT (Information and Communication Technology) has gone through a radical transformation driven by efforts to reduce the carbon footprint. To achieve the required data densities at the same or lower power (data rate per meter squared), Wi-Fi/WiGig solutions implement beamforming. Beamforming requires multiple antennas with individual phase shifters. From the technical side, digital beamforming is preferable but it increases hardware complexity, power consumption and cost. Current designs are merely based on wideband analogue phase shifters being inappropriate in severe multipath propagation environments.

While it is expected that current technology problems can be overcome in the future, it is vital to consider further technologies probably leading to even smaller cells. Therefore, remember that RF is just one part of the electromagnetic spectrum and that the light along with the infrared spectrum has, for the most part, been underutilised for wireless communications. The visible light spectrum alone stretches from approximately 430 THz to 770 THz, which means that there is potentially more than 1000x the bandwidth of the entire RF spectrum of approx. 300 GHz. Both the visible light spectrum and the infrared spectrum are globally unlicensed. Light Communications (LC) devices are promising to make use of this previously untapped spectrum.

The applications for LC are limitless. Anywhere solid state lights, e.g., LED lights, are installed to provide illumination, there can also be high speed wireless data communications.

The success of LED lighting has been nothing less than earth shattering over the last 10 years. Common LED bulbs today consume 85% less energy than their incandescent counterparts and their deployment is poised to have a massive impact on the energy mix, with lighting accounting currently for as much as 15% of global electricity consumption and 5% of worldwide greenhouse gas emissions.

Costs have been slashed down through improvements in manufacturing and higher wall-plug efficiency. Costs per LED bulb remain higher than for incandescent and fluorescent technologies but a much longer lifespan up to 25,000 hours and energy savings make the cost per lumen much more competitive.

As a consequence, the LED lighting market share is already 40-50% (depending on the geography) and 70% of a global $100bn general lighting market will stem from LED shipments (lamps and luminaires) as early as 2020. In the US alone, LED installed stock is expected to grow from 6% in 2016 to close to 60% in 2025 and 90% in 2035.


Figure 3: US lighting service forecast 2015 to 2025, Note: CFL = compact fluorescent light; HID = high intensity discharge. Source: US Department of Energy (2016)

Today, there are real life applications and benefits for implementing LC, examples of which are:

  1. Indoor Positioning – Because of the confined nature of light propagation in indoor environments, “indoor positioning” using LC is promising to deliver a variety of location-based services to networked wireless devices.
  2. Secure Communications – Since light does not pass through opaque materials, it can offer a secure communications channel created by the virtue of its propagation characteristics which can be user-controlled in case of visible light.
  3. RF-restricted environments – LC provides wireless data connectivity in environments such as petrochemical plants, hospitals, manufacturing plants, nuclear power generating stations, underground mines, underwater etc, where the use of RF is not wanted, not secure or actually impossible.

Considering that LED lighting will eventually become ubiquitous, the stage is set to transform lighting into a backbone for information.


There are multiple technologies and concepts that use light for communications. Needless to say that the use of light is indispensable in worldwide optical fiber communication networks forming the backbone of the Internet. But light can also be used for wireless communication. As a simple example, the Infrared (IR) communications between a remote control and a television can be considered as light communications with very low data rate. Similarly, providing gigabit per second connectivity between buildings with dedicated free-space optical (FSO) links, most frequently using IR light, is another form of light communications with very high data rate, and it is essential to identify the relevant use-cases and differentiate the appropriate technologies enabling them.

The wider category of all technologies using the light spectrum for wireless communications is also often referred to as Optical Wireless Communications (OWC). In this context, there are broadly three different categories of OWC technologies:

  • Free-space Optics (FSO),
  • Optical Camera Communications (OCC), and
  • LiFi

Free-space Optics has been used extensively to establish point to point communications over long distances, largely serving use-cases around wireless backhauling for urban areas, as a fiber replacement and will not be the point of focus here. Instead, we try to provide some clarity around the differences between OCC and LiFi, as these technologies are frequently confused.

Defining OCC 

OCC uses the visible and near infrared spectrum for one-directional (simplex) communications at very low data rates (few bit/s to kbit/s) in a broadcast manner. The illumination LEDs produce fixed codes that are embodied in the light and can be used by OCC receivers. Due to the lack of a return channel, however, there is no inter-cell mobility support, i.e., no handover or roaming.

In general, the energy used for illumination can be used to provide this broadcast signal consistently, i.e., as long as the light is turned on. OCC could be used to provide accurate indoor positioning and limited amounts of information similar to how the Global Positioning System (GPS) is used to offer positioning in outdoor scenarios. Therefore, OCC can serve substantially similar use-cases as GPS, except it is operating in indoor environments.

OCC could be combined with RF technologies like 4G/5G, Wi-Fi, Bluetooth and more to provide a comprehensive location-based services proposition, offering sub-meter indoor precision. These systems have already been tested and effectively deployed to offer operational improvements for retail chains, shopping centers and even large office spaces and venues.

Defining LiFi 

LiFi is defined as an optical wireless broadband access technology that uses the visible and infrared light spectrum to provide bi-directional (transmit and receive) capability. It is able to support uplink and downlink in a point-to-point or point-to-multipoint topology and provide multiuser access in this way. It has been demonstrated that LiFi can offer mobility support for both intra-cell and inter-cell movement link adaptation and handover. There are two principal version of handover:

  • Horizontal handover– the ability to maintain a data connection to the network as a user moves from once cell to another using the same communications technology, like 4G, Wi-Fi or LiFi; and
  • Vertical handover – the ability to maintain a data connection to the network as a user changes the principle radio access technology, i.e., moving from 4G to Wi-Fi or from Wi-Fi to LiFi.

The LiFi infrastructure comprises of multiple LED light bulbs that form a wireless communication network, offering a substantially similar user experience to other wireless communication technologies such as Wi-Fi (except using the light spectrum) though horizontal handover. In the future, LiFi could be developed to offer interoperability with Wi-Fi, 4G or other radio frequency (RF) systems where a user can be “opportunistically”, even concurrently, connected to LiFi and other RF to offer the best user experience.

LiFi is unique in that the same light energy used for illumination is also used for broadband data communication. It is a platform technology with the potential to complement and extend existing capabilities of RF technologies. LiFi provides a high-speed, secure, dense and reliable wireless network for enterprise and home environments and acts as an enabler for smart buildings, intelligent transport and smart cities. 


Understanding LiFi Technology

The term LiFi was coined by Professor Harald Haas, during a Ted Global Talk in 2011 where he demonstrated LiFi to a worldwide audience for the first time. LiFi extends the concept of visible light communication (VLC) (where even smoke signals can be considered as early forms of VLC)  to achieve, specifically:

  • high speed;
  • bi-directional; and
  • fully networked

optical wireless communications. In areas covered by networked ambient lights, the LiFi system supports random user locations. A LiFi system is composed of multiple small cells, also referred to as a LiFi attocell network since the cell sizes have radii of a few meters or less. Therefore, LiFi not only benefits from additional free spectrum, but it also takes the small cell concept to new levels because the light spectrum can and is reused more frequently compared to current mobile radio systems. As a consequence, a higher network capacity can be achieved.

Figure 4 illustrates the key parameters which define LiFi. LiFi transmission speed is in the 10Mbps-1Gbps range with LED lighting and can reach more than 5Gbps with new generations of Solid State Lighting devices.


Figure 4: Broad system parameters which define LiFi. Duplex mode refers to communication system where two connected parties or devices that can communicate with one another in both directions. There are two types of duplex communication systems: full-duplex (FDX) and half-duplex (HDX). In a full-duplex system, both parties can communicate with each other simultaneously on the same time and frequency resources. In a half-duplex system, each party can communicate with the other but not simultaneously; the communication is one direction at a time either in time or frequency. The dashed red-line outlines that LiFi systems are capable of FDX communications but also frequently use HDX communications.

LiFi Networking 

Figure 5 illustrates the concept of a LiFi attocell network. The room is lit by a number of light fixtures, which provide illumination and an optical access point (AP) to users within the illumination pattern of the light. The illumination can be modulated at high rates, imperceptible to the human eye and providing an optical downlink. An optical uplink is implemented by using a transmitter on the user equipment (UE), often using an IR source (so it is invisible to the user), and a receiver close to the light fixture. Each of these light fixtures, acting as wireless LiFi APs, creates an extremely small optical cell (an attocell), which is available in addition to the RF coverage in the room. Therefore, LiFi has great potential to contribute in solving the difficult problem of indoor wireless coverage, which is particularly important as more than 80% or the wireless traffic is consumed indoors. 


Figure 5: The concept of LiFi attocell networks applied to indoor wireless networking as part of a heterogeneous network

Increasing the density of wireless APs, however, also impacts the cost of the associated backbone. Fortunately, power and data can be provided to each light fixture using a number of different techniques, including power over Ethernet (PoE) and powerline communication (PLC). Individually both PoE and PLC have benefits and drawbacks, but taken together they could cover a wide array of use-cases in current buildings. In addition, these developments and their integration into the overall building systems are being driven by two other macro-trends. On the one hand, the increasing interest in connected Smart Building technologies which is making use of both existing and new infrastructure provides massive potential in order to provide energy savings but also to gain a better understanding of how buildings are used thus increasing both comfort and efficiency of building owners and users. On the other hand is the ongoing LED lighting revolution, where we are seeing conventional light fixtures and lighting infrastructure investments being replaced by modern LED fixtures. The combination of these trends provides a unique opportunity for the deployment of LiFi access points.

In cellular networks, dense spatial reuse of the wireless resources is used to achieve very high data density - bits per second per square meter (bps/m2). However, the links using the same channel in adjacent cells interfere with each other, which is known as co-channel interference (CCI). Figure 6 illustrates CCI in an optical attocell network


Figure 6: CCI occurs in the region where the same light spectrum of neighboring APs overlaps, and when these APs use the same modulation bandwidth for data encoding.

The move from point to point links to full wireless networks based on light poses several challenges. Within each cell, there can be a number of users and therefore a sophisticated medium access scheme is required. The provision of an uplink can also require a different approach from the downlink due to limited power consumption. Indeed, depending on the wireless service, uplink and downlink traffic can be symmetric or asymmetric. Asymmetric traffic provides opportunities for mechanisms that result in improved energy efficiency.



Figure 7: A room of size 2.5 m × 5 m is equipped with two LiFi luminaires installed at 3 m height pointing vertically downwards. The LiFi luminaires are illustrated by two blue squares in subplot (a). Both luminaires use the same visible light spectrum to transmit independent information. Vertically upwards pointing receivers at 0.75 m desk height are assumed. The illuminance at desk height is illustrated in subplot (b). The resulting SINR assuming a receiver FoV of 45 is depicted in subplot (c).

LiFi attocell networks can provide extra capacity without interference to RF networks that may already exist, and therefore have the potential to augment 5G cellular systems in a cost-effective manner. Figure 7 (b) shows the resulting illuminance at desk height of 0.75 m, when the luminaries are mounted at a ceiling height of 3 m. In the particular example, the lights are placed such that within the plane at desk height, 90% of the area achieves an illuminance of 400 lux based on a typical illumination requirement. Figure 7 (c) depicts the resulting signal-to-interference-plus-noise ratio (SINR). The region where the light cones overlap will be subject to strong CCI if the same wireless resource is used in both cells, and the SINR drops significantly. It is interesting to note that the SINR can vary as much as 30 dB within a few centimeters. The same graph suggests that the peak SINR could be in the order of 50 dB, which is two to three orders of magnitude higher than in RF based mobile systems. Note that the peak SNR in RF systems is due to interference from backwards-radiating side-lobes of antennas.

The considerations here do not account for the presence of diffused light, which is reflected from surrounding objects. The diffused light may be 20-30 dB below the signal coming from the direct line-of-sight. Without interference management, the achievable data rate would strongly depend on the network layout, the location of the receiver and its field of view (FoV). Similar to mobile radio, sophisticated interference mitigation techniques are required to ensure that a LiFi device can achieve a high SINR in the region with strong CCI. Indeed, a fundamental solution is coordinated multiple point (CoMP) in which geographically separated transmission points coordinate their transmissions to a terminal such that they combine constructively at the receiver and interference combines destructively at the same time. In this way, any inter-cell interference is avoided and the spectral efficiency of the system is improved both on average and at the edges between the cells. While this is an interesting research topic, LiFi networks can initially be deployed easily by using much simpler interference management techniques similar to current mobile networks. Performance can then be improved if complexity and overhead are increased. 

LiFi will have a catalytic effect for the convergence of two major industries: i) the wireless communications industry and ii) the lighting industry. With an accelerating pace of penetration in the lighting market, LEDs are providing the opportunity of a better value proposition with increased cost/energy savings and open new business opportunities for manufacturers and financiers. Indeed, lighting control systems are greatly expanding the functions that can be performed by a luminaire, making lighting a central part of the Smart Building, Smart City, IoT and Edge concepts. New business models, such as 3rd party ownership of the lighting infrastructure, are already emerging. LiFi builds on these systems and concepts to satisfy a growing need of our society beyond illumination – wireless communications. The combination of these innovative concepts with LiFi will, therefore, provide a business model driven ‘pull’ for the lighting industry to enter what has traditionally been an ICT market. In the wireless industry, and in the broader context of 5G and indoor environments – where the majority of usages and demand originates – Heterogenous Networks will provide an improved quality of service and coverage. A hybrid LiFi and RF system would improve indoor connectivity and capacity by offering to off-load the traffic. Indeed, LiFi has the potential to open additional unlicensed spectrum and facilitate cost-effective deployment of extremely dense indoor networks, both essential to reducing the required investment for the next generation of wireless connectivity. However, an important prerequisite for the large-scale adoption of LiFi technology is the availability of standards. In this context, efforts have started in IEEE 802.11 to standardize LiFi as another physical layer in the IEEE 802.11 wireless local area networking group. 


Figure 8: The transition from cm-wave to mm-wave is already happening in 5G. The paradigm shift that LiFi introduces is the move from cm-wave cellular communication to nm-wave cellular communication. Clearly, LiFi is complementary to RF, and adds substantial capacity to our wireless networks which are increasingly suffering from the RF spectrum crunch


The successful mass market deployment of LiFi will require further developments to reduce, costs, energy consumption and continued technology miniaturization. Critically, it will need a common technical standard and a comprehensive ecosystem (a market body) that will drive forward the ubiquitous adoption of the new technology in a wide range of applications. There is a need for a broad ecosystem of partners consisting of end-users, telecom providers, network infrastructure vendors, lighting companies, chipset manufacturers, device manufacturers, testing houses, training organizations, specialist LiFi companies and many more.

Fortunately, the IEEE 802.11 working group already has many of the key actors in this new ecosystem. Indeed, the IEEE 802.11 Working Group approved the Project Authorization Request (PAR) and Criterial for Standards Development (CSD) produced by the LC Study Group (SG) at its January 2018 meeting. The IEEE has now agreed the formation of a Light Communications Task Group (TG bb) to work on an LC amendment to the IEEE 802.11 standard.

There are a number of standards that already exist or are being created to standardize various light communication technologies. The first IEEE 802.11 text already contained an IR PHY, which was eventually removed due to lack of commercial traction. The second IEEE standard for light communication is the IEEE 802.15.7-2011, which is now being revised to have a greater focus on OCC.

The difference between the proposed standard within the IEEE 802.11 and the existing IEEE 802.15 LC standards is the use of the 802.11 MAC as well as the reuse of associated services that are focused on wireless local area networks. This new approach will ensure that LiFi is focused on local wireless area networks relative to the existing (IEEE 802.15.7m and IEEE 802.15.13) efforts that are focusing on deploying the technology for wireless specialty networks which have less challenging requirements on energy efficiency, form factor and cost.

There is also increased activity in the market with the world’s first LiFi Forum was recently organized and hosted by Orange in late 2017. This meeting also saw the formation of an industry body including Orange, Deutsche Telecom, Liberty Global, Nokia, Lucibel, Zero.1, VLNComm, pureLiFi, University of Edinburgh, Fraunhofer Heinrich Hertz Institute, and others that will seek to cooperate on the development of the  market and drive broader commercial awareness of the technology with participation from the complete ecosystem of partners required to make LiFi a global success.


A LiFi standard could be released as early as 2021, a date targeted and agreed by the IEEE 802.11 Working Group, and ensure that LiFi can be integrated seamlessly across the ecosystem, from chipset developers, to infrastructure providers, tier 1 telecoms and more.

The Wi-Fi Alliance announced at the start of 2016 that Wi-Fi shipments have reached 12 billion units, and surpassed 15 billion units by the end of 2016. With an installed base of more than 6.8 billion devices, Wi-Fi has become one of the most prolific technologies around the world. Almost every telecom provider around the world has a deployed network of Wi-Fi access points for consumer, enterprise and public access. Providing services to a broad customer base requires significant backbone network integration. Telecom providers are familiar with the integration and operation of IEEE 802.11 based networks as part of their heterogeneous radio access network infrastructure with complete integration for user management, billing systems, voice-call handover, security and more. This is a key friction point that must be addressed when considering the deployment of a LiFi network.

Wi-Fi is tipped to play a central role in the success of 5G, “which, unlike previous generations of mobile technologies, will rely on multiple Radio Access Technologies in unlicensed, shared and licensed spectrum which Wi-Fi will help to bridge”, the Wireless Broadband Alliance (WBA) announced. A report by the Wireless Broadband Alliance (WBA) recently identified monetization strategies for Wi-Fi in 2018, with location-based services ranking highest at 37.5 per cent, followed by roaming (33 per cent) and marketing analytics (almost 33 per cent). Traditional use cases such as consumer data access and Wi-Fi offload are still central to many providers, while three areas were highlighted as potential near term revenue drivers:

  • improving in-home experience and extending the use of Wi-Fi to smart home services;
  • enterprise services; and
  • expanding the roaming model.

The tight integration of LiFi with other IEEE 802.11 technologies, such as the coexistence and hand-over with other 802.11 PHY types by using Fast-Session Transfer (FST allows  different  streams  or  sessions to  transfer  smoothly from  one  channel  to  another  in  the  same  band  or different bands, i.e., different PHYs allows  different  radios  in  the  same  device to  operate simultaneously or not simultaneously, making 802.11bb compatible  with  the  forthcoming 802.11ax standard and  other existing standards, such  as  802.11a/b/g/n)  will reduce time-to-market for LiFi. This re-use of the existing IEEE 802.11 technologies will help dramatically accelerate the time to market for the technology by removing a key friction point when considering backbone integration and building of associated services.


LiFi is a technology that is poised to impact a large number of industries. It is likely to become a complementary wireless access technology in the broader context of 5G (see Figure 8) opening new use-cases for the Internet of Things (IoT) and Edge intelligence, helping to drive new industry automation capabilities, e.g., Industry 4.0. Moreover, Li-Fi has the potential to create more value in society with added functionalities for smart lighting, to enable new intelligent transport systems, to enhance road safety in the dawn of driverless cars, to create new cyber-secure wireless networks, to enable new ways of health monitoring for aging societies and much more. The applications for LiFi are limitless and this technology’s impact on industry, and society are yet to be fully conceived. However, it is certain the impact will be pervasive and transformative.


serafimovski sizedDr. Nikola Serafimovski has been working with major companies in the area of LiFi technology and commercialization to create a comprehensive ecosystem of relevant partners for the mass market deployment of LiFi, leading the creation and cultivation of the LiFi ecosystem, marketing, sales and standardization of the technology. Previous experience with T-Mobile and T-Home in Macedonia focused on mobile network deployment and analysis as well as database app development. Nikola is the current Chair of the IEEE 802.11 Light Communications Study Group, the Vice-Chair of the IEEE 802.15.13 Task Group on Multi-gigabit Optical Wireless Communications and the former Secretary of the IEEE 802.15.7r1 Task Group on Optical Wireless Communications.

Nikola completed his Masters of Science in Communications System Engineering with Jacobs University Bremen in 2007 including a joint MSc thesis with the University of Edinburgh on Visible Light Communications in 2009 before completing his Ph.D. with the University of Edinburgh on Spatial Modulation, which is a novel physical layer modulation technique, in 2013.

Ronan Lacroix is a Senior Expert Alliances & Business Development within the Technology Innovation division of the Deutsche Telekom Headquarters in Bonn, Germany. Besides the Management of DT’s strategic business alliances, he has been driving Open Innovation within the CTO organisation, working on the development of new business concepts and propositions based on innovative technologies and partners. In his role, he has been over the past 2 years evaluating and promoting the LiFi Technology as a complementary access technology to WiFi and Cellular networks in the wider context of 5G.

Previously, Ronan worked as a Global Product Manager within the Product & Innovation division of Deutsche Telekom, working with the GSMA community on the definition of cross-operator enabling products (APIs) for 3rd-parties based on Operator capabilities such as Identity, Payment or Messaging.

Before that, Ronan gathered extensive business and technical expertise holding various international and cross-functional management positions within major telecommunications and high-technology companies. Ronan received a Master’s Degree in Engineering in 1993 from the French “Ecole Nationale Supérieure des Télécommunications de Bretagne” with a specialisation in image processing and pattern recognition and is fluent in English, French and German.

Micheline Perrufel is Innovation Project Director at Orange Labs. 8 000 employees are now dedicated to Orange research and innovation. With 6,844 patents in its portfolio, Orange contributes to many cooperative projects, research partnerships with universities, laboratories or industry. Expert in the technologies of physical interactions, Micheline Perrufel works for the new LiFi technology, leads customer relationship projects for enterprises or at Home and anticipate the evolution of the Orange Boxes services. In her missions, Micheline Perrufel also exchanges with other telecom operators anticipating the next topics of innovation. Micheline's expertise is based on his training (ENST and ESSEC) as well as her professional experience. After leading technical teams working on Orange's core networks, Micheline helped launch the GSM mobile network in France. Passionate about wireless communications, Micheline is now encouraging the hybridization of radio, ultrasound and radio technologies to deliver more intelligent services.

Sylvain Leroux is Customer Marketing Director for Datavenue an IoT program, and he is also Marketing Director for LiFi & Geolocation anticipation projects at Orange, one of the world’s leading telecommunications operators. Sylvain is an expert in digital transformation, change management and innovation (tech or usages): his focus is about to structure or manage game changing partners, ecosystems and services.

Sylvain is passionate about hybridization. He was previously building bridges between Physical and Digital worlds in the retail field. He has an extensive knowledge on opening new frontiers between Digital, Culture and Business: he has created with Erik Orsenna the first book award mixing professionals and internet users, gathering a community of 200K reading enthusiasts, and developed a Transmedia project with famous author Alexandre Jardin.

He has also worked for Africa, Middle East & Asia markets as Business Partner Communication where he mainly focused on Corporate Social Responsibility and Branding.

Simon Clement: Researching, trialling and implementing emerging technology. Working across multiple technologies with a focus on Network, Voice, Mobile and Television and interlacing new services through these basic service sets. Most recently focused on Wireless networking running high profile WiFi and LTE trials alongside TV White Space trials, LPWAN and LoRa trials and supporting use cases for Connected Cities.

Vendor experience in Network Design, Architecture, Software Engineering and Complex Integration for Class 4 and Class 5 switching technology in both Wireless and Wireline Carrier markets.
Implementation management for global deployments of switching architecture including work on all 5 continents. New product and new service development and programme management. Technical expertise in VoIP, TDM, Broadband, Carrier Data, WiFi and other wireless technology. Operating Company experience in product, deployment and technical architecture consultancy. Technical consultancy level expertise within VoIP and TDM Voice, Narrowband and Broadband Access Technologies, Mobile Voice and Data, Mobile TV, WiFi, LoRa, LPWAN and many other wireless technologies.

Nirlay Kundu is a Distinguished Engineer at Verizon Innovation Labs. He is currently managing Infrastructure Operations and Deployment in Verizon’s datacenters. Prior to this, Nirlay was involved in evaluating and choosing vendors for new technology, doing proof of concepts in the LTE EPC space. Prior to Verizon, Nirlay worked at Oracle, as a founding engineer at Rivermeadow Software, Motorola and Lucent. Nirlay holds several Advisory Board level positions. He has more than 20 years of expertise in the telco space and worked across several continents. He holds Bachelors and Masters degrees from Jadavpur University, IIT Kharagpur, Leicester University and MBA from Babson College. He is a frequent speaker and events related to telecommunications. 


Dominique Chiaroni was born in Ajaccio, in April 27th, 1962. Graduated in Mechanics (IUT d’Aix-en-Provence), in Thermal sciences & Physics (Bachelor & Master at the University of Corsica), and in Optics and Microwaves (Engineer diploma obtained in 1990 from Institut National des Télécommunications), he was engaged in 1990 by Alcatel CIT to explore optical switching technologies and related systems and networks. Since 2000, he focused mainly his research on the design and the eco-design of energy efficient hybrid systems for different network segments from the core to the access network. Currently working in the IP and Optical Networks Lab within Nokia Bell Labs France, his focus is on low cost and low power consuming smart fabrics for 5G applications.  He actively participated to several European and National projects and is currently the project leader of the French ANR N-GREEN project (2016-2018).  Chair or co-chair of International Conference or Workshops he participates regularly to technical committees of many International Conferences. Distinguished member of the Alcatel-Lucent Technical Academy since 2003, Chapter Chair of the French Chapter from 2005 to 2013, he actively participated to the organisation of many events. He received more than ten internal and external awards. He authored and co-authored more than 200 publications and patents including contributions in books.

Gaurav Patwardhan was born in India on February 17, 1988. He received B. Eng. in Electronics from Pune University in 2011. After a brief stint in wireless security industry he graduated with high distinction in 2014 from North Carolina State University with a MSc. degree in Computer Networks specializing in wireless networks. Currently he works as a wireless protocol architect and a software test engineer in Aruba Networks (an HPE company). His technical interests include wireless communication technologies, network security and machine learning. He holds multiple patents and has co-authored paper in these fields. He also actively participates in the IEEE Standards Association procedures for evangelizing and ratifying new wireless technologies.


Dr Andrew Myles received his BSc in Computer Science & Pure Mathematics in 1985, and his BE in Electrical Engineering (First Class Honours & University Medal) in 1987, both from the University of Sydney in Australia. He received a PhD for his work on aspects of Mobile-IP and on a MAC suitable for operation with a 60Hz PHY from Macquarie University in Australia in 1996.

Dr Myles has had a diverse career, having worked in corporate research labs (Hewlett Packard Labs in the United Kingdom from 1987-1989, working on FDDI & DQDB systems and standards), university research labs (Macquarie Park Research from 1990-1994 in Sydney, working on SDMS systems, router architectures, Mobile IP and 60GHz wireless systems), management consulting and a technology start-up.

Dr Myles is currently the Manager of Enterprise Standards in the Chief Technology & Architecture Office at Cisco Systems.

Dr Myles has been a voting member of the IEEE 802.11 Working Group since 2001, and was the Editor of IEEE 802.11h (Spectrum Management to enable use of 802.11 5GHz systems in Europe) from 2001-2003. He became the Chair of the IEEE 802 JTC1 Standing Committee in 2009, which is the group coordinating activity between IEEE 802 and ISO/IEC JTC1/SC6. He has undertaken a similar role as the Head of Delegation of the US National Body delegation to ISO/IEC JTC1/SC6, and a participant of the corresponding US National Body Project 5 TAG.

He was a Director on the IEEE Standards Association Standards Board in 2015, and was appointed as a Governor on the IEEE Standards Association Board of Governors in 2016-17. Dr Myles has also promoted the use of IEEE 802.11 through his work in the Wi-Fi Alliance. He has been a Director of the Wi-Fi Alliance Board since 2003, was the Vice-Chair in 2006 and the Chair from 2006-2011. He briefly acted as the organisation’s Executive Director in 2007. He is currently the Chair of the Wi-Fi Alliance’s Liaison Committee and Secretary of the Board.

Christophe Jurczak: A graduate of Ecole Polytechnique and Ecole Normale Supérieure in France, Christophe Jurczak also holds a PhD in quantum physics from Ecole Polytechnique / Institut d'Optique. After starting at the French Ministry of Defense as a program manager in optronics, Christophe Jurczak has had a career in Europe and in the United States in the renewable energy sector. Based in Palo Alto, CA, he joined the LUCIBEL group in 2017 as Chief Scientific Officer in charge of Lucibel’s technology roadmap (LiFi, OCC and circadian lighting) and the development and implementation of new use cases that these technologies make possible. He is a member of the IEEE802.11 Light Communications Task Implementation Group and a LiFi evangelist.


Marc Fleschen: Marc was an early advocate of technology and its application in both business and lifestyle environments. His combined passion for technology, together with his strategic business acumen and international network, make him the ideal leader for Zero.1.

A French native, Marc’s interest in international commerce started at an early age as he pursued his Bachelor's degree in Economics, (1996), and a Master's Degree in International Commerce (2000). A natural entrepreneur, Marc chose the fast-growing innovative city of Dubai as the base for his international operations when he established his company, JML Investment Group, in 2004. Less than three years later JML represented more than 32 European brands across 45 outlets, in the United Arab Emirates. The Group also operated an executive chartered airline company with a fleet of 24 planes, alongside several other retail, real estate and marketing businesses.

Marty Ragusky: In addition to working to extend the knowledge of LiFi technology to Government Agencies, technology developers, service providers, manufacturers, distributors and functional users throughout the world, Marty has an extensive background in C4ISR and intelligence data handling systems in capacities ranging from systems analyst through program manager and Vice President where he conducted requirements analysis and traceability, functional analyses, system/subsystem design & development (H/W & S/W), systems integration, test and evaluation, modeling and simulation, configuration management, risk management, and supportability engineering studies (feasibility, cost, and conformance).  Additionally, Marty was a program manager for a number of critical wireless communication initiatives including: a complex wireless communications system (450/900MHz, 5/11/18GHz) that involved RF system design, link analyses, path analyses, scheduling, site surveys, pricing, logistics, managing multi-vendor quotes and developing teaming partnerships for a 130+ PTP-PTMP network throughout Prince William County VA; and, the design, installation and commissioning of a wireless network for a 150 acre campus at DC Water that consisted of more than 40 access points.

Volker Jungnickel (M’99) received doctoral and habilitation degrees in Physics and Communications Engineering from Humboldt University and Technical University in Berlin in 1995 and 2015, respectively. He joined Fraunhofer HHI in 1997 working on optical wireless communication, multiple antenna techniques in mobile networks and fixed access network technologies. Besides, he serves as Privatdozent at Technical University in Berlin where he gives lectures and supervises Bachelor, Masters and Ph.D. thesis. Currently, Volker serves as chair for IEEE P802.15.13 task group on “Multi-Gbit/s Optical Wireless Communication” and secretary for IEEE 802.11 study group on “Light Communications”.


Dimitri Kténas received the Dipl.-Ing. degree in Electrical Engineering from the Ecole Nationale Supérieure d’Electronique et de Radioélectricité (ENSERG), Grenoble (France), in 2001. From that time, he has been with CEA-Leti in Grenoble, France. His main current research interests are PHY, MAC and cross-layer optimization for both 5G cellular networks and LiFi systems. He has been involved in several European projects (4MORE, CODIV, ARTIST4G, EXALTED, iJOIN, 5GNOW, FANTASTIC-5G, mmMAGIC) and was the coordinator of the French OPUS project that dealt with LTE optimization. From 2010 to 2015, he was leading the Wireless Communication System Studies laboratory within CEA-Leti, which was in charge of baseband processing and MAC layer studies for wireless systems. In 2013, he launched the Visible Light Communication activities at CEA, first with internal funding from CEA-Leti, then with bilateral contracts with the French startup Luciom (2014-2016) that was acquired by Philips Lighting in December 2016. Since 2016, he was leading the Broadband Wireless Systems Lab within CEA-Leti, which is in charge of algorithm studies and HW/SW implementation of digital signal processing and protocols for both 5G and LiFi systems. In March 2018, he was appointed Department Head of Wireless Technologies (70+ persons), focusing on 5G, IoT and Optical Wireless Communication, from baseband to network layers including propagation modeling and antenna design. He has published 60+ scientific papers in international journals and conference proceedings and 5 book chapters, and is the main inventor or co-inventor of 13 patents.

Harald Haas received the PhD degree from the University of Edinburgh in 2001. He currently holds the Chair of Mobile Communications at the University of Edinburgh, and is the founder and Chief Scientific Officer of pureLiFi Ltd as well as the Director of the LiFi Research and Development Center at the University of Edinburgh. His main research interests are in optical wireless communications, hybrid optical wireless and RF communications, spatial modulation, and interference management in wireless networks. He first introduced and coined ‘spatial modulation’ and ‘LiFi’. LiFi was listed among the 50 best inventions in TIME Magazine 2011. Prof. Haas was an invited speaker at TED Global 2011, and his talk: "Wireless Data from Every Light Bulb" has been watched online more than 2.4 million times. He gave a second TED Global talk in 2015 on the use of solar cells as LiFi data detectors and energy harvesters. This has been viewed online more than 2.0 million times.  He has published more than 400 conference and journal papers including a paper in Science. He co-authors a book entitled: "Principles of LED Light Communications Towards Networked Li-Fi" published with Cambridge University Press in 2015. Prof. Haas is Associate Editor of the IEEE/OSA Journal of Lightwave Technologies. He was co-recipient of recent best paper awards at VTC-Fall, 2013, VTC-Spring 2015, ICC 2016, ICC 2017 and ICC 2018 He was co-recipient of the EURASIP Best Paper Award for the Journal on Wireless Communications and Networking in 2015, and co-recipient of the Jack Neubauer Memorial Award of the IEEE Vehicular Technology Society. In 2012 and 2017, he was the recipient of the prestigious Established Career Fellowship from the EPSRC (Engineering and Physical Sciences Research Council).  In 2014, he was selected by EPSRC as one of ten RISE (Recognising Inspirational Scientists and Engineers) Leaders in the UK. In 2016, he received the outstanding achievement award from the International Solid State Lighting Alliance. He was elected a Fellow of the Royal Society of Edinburgh in 2017. Prof. Haas has been elevated to Fellow of the IEEE in 2017.


Editor: Paul Nikolich

Paul Nikolich has been serving the data communications and broadband industries developing technology, standards, intellectual property and establishing new ventures as an executive consultant and angel investor since 2001. He is an IEEE Fellow and has served as Chairman of the IEEE 802 LAN/MAN Standards Committee since 2001. As 802 Chairman he provides oversight for 75 active 802 standards and the 50+ concurrent 802 activities in wired and wireless communications networking. 802 has over 750 active members and manages relationships between IEEE 802 and global/regional standards bodies such as ISO, ITU, ETSI, regulatory bodies and industry alliances.   He is a member of the IEEE Computer Society Standards Activities Board and active leader in the IEEE, the IEEE Computer Society and the IEEE Standards Association. He is a partner in YAS Broadband Friends LLC and holds several patents, serves on the boards of directors and technology advisory boards of companies developing emerging communications technology along with being a board member of the University of New Hampshire’s Broadband Center of Excellence. Mr. Nikolich has held technical leadership positions at large and small networking and technology companies (e.g., Broadband Access Systems, Racal-Datacom, Applitek, Motorola, Analogic). In 1978&79 he received a BS in Electrical Engineering, a BS in Biology and a M.S. in Biomedical Engineering from Polytechnic University in Brooklyn, N.Y (now the NYU Tandon School of Engineering).


Raul Muñoz, Josep M. Fàbrega, Ricard Vilalta, Michela Svaluto Moreolo, Ramon Casellas, Vilalta, Laia Nadal, Ricardo Martínez, Centre Tecnològic de Telecomunicacions de Catalunya (CTTC/CERCA)

IEEE 5G Tech Focus: Volume 2, Number 2, May 2018 


A holistic approach is essential in order to define a converged mobile and fixed access infrastructure, both at structural and functional level, instead of having multiple infrastructures delivering the same or similar services. This converged infrastructure should maximize: i) the benefits of the high-capacity and cost-effective optical access network solutions, addressing not only the transport requirements of fixed subscribers as done so far, but also for 5G mobile x-haul (fronthaul/backhaul) networks, and ii) the SDN/NFV architectural frameworks to address the challenge of jointly managing and operating heterogeneous access and transport networks and distributed cloud infrastructures to offer end-to-end network services and  network slice services for fixed and mobile users.

1. Introduction 

Mobile radio access networks (RAN) and fixed optical access networks have evolved and developed independently. The aggregation and transport of mobile and fixed traffic in the access segment is implemented today by means of an overlay of heterogeneous transport network technologies tailored to some specific service. On the one hand, fixed optical access networks have been designed to meet the demands and requirements for the residential and enterprise subscribers (e.g. NG-PON1/2). These networks are typically passive optical networks (PONs), where a passive optical tree structure is used to connect the central office with the end users. The reason is that they are simple, flexible, and scalable, while featuring low maintenance and operation costs [1].

On the other hand, mobile transport networks can be traditionally sorted out as backhaul and fronthaul solutions. Mobile backhaul is the transport connection/network between the base-band units (BBUs) and the mobile core (i.e., EPC), and the mobile fronthaul is the transport connection/network between the remote radio head (RRH) and the BBU. Mobile backhaul has low requirements for bandwidth and delay, and traditionally is deployed in packet-based network infrastructure (e.g. Ethernet, IP/MPLS). Instead, mobile fronthaul has very stringent requirements in terms of high-bandwidth and low-delay because it is required to transport the digitally sampled radio waveform from the base station to the central office where the pool of BBUs is located. This architecture is known as cloud/centralized architecture (C-RAN), unlike the distributed RAN, where the BBUs are collocated with the RRHs in the base stations (e.g. 4G eNodeB). The most widely used standard interface for the fronthaul is the common public radio interface (CPRI) and is deployed in overlay C/DWDM links built specifically for this purpose, making use of optical transceivers supporting CPRI. These transceivers are known as digital radio over fiber (dRoF). The main drawback of CPRI is that it does not scale, in terms of bandwidth requirements, for the massive MIMO antenna deployments foreseen in 5G. 3GPP is proposing to reduce the bandwidth and latency requirements for 5G, while keeping most of the benefits of the C-RAN architectures, by performing a function split of the baseband processing in eight options that have been analyzed thoroughly in literature [2]. In this approach, the BBU functions are split into the RRH and two new logical entities; central unit (CU) and distributed unit (DU). A CU can support multiple DUs, and each DU is only associated to only one CU. Most of the controlling functionalities are centralized on CU, while the fast scheduling on the air interface is realized on DU. It brings the introduction of two new transport networks between the CU and DU (known as midhaul), and between the DU and the RRU (known as next generation fronthaul interface – NGFI). 3GPP has already chosen split option 2 (i.e. split between PDCP and RLC) for the midhaul, but it is still open between the DU and RRH. This approach enables the virtualization of BBU functions (i.e., DU and CU) in local datacenters as well as the packetization of the NGFI to provide more efficient network utilization in ultra-dense scenarios. However, the packet-based NGFI will introduce new requirements in terms of jitter and synchronization that have to be properly addressed. An alternative solution that is being investigated to reduce the bandwidth requirements is to use analog radio over fibre (aRoF) transceivers, where the radio waveforms are directly modulated onto light for connecting BBUs and RRHs.

Additionally, the wide adoption of Network Function Virtualization (NFV) concepts, including BBU virtualization requires cloud services for the deployment of virtualized network functions (VNFs). The virtualization of network functions that are typically deployed in specialized and dedicated hardware (e.g. mobile evolved packet core –EPC) is of crucial importance for 5G.  Much like 5G, IoT also requires core computing and storage infrastructures in order to perform IoT analytics from the data collected from sensors and actuators (e.g., temperature monitoring, energy consumption measurement, etc.). Traditionally, cloud services have been implemented in large datacenters (DCs) in the core network. Cloud offers high-computational capacity with moderate response time, meeting the requirements of centralized services with low-delay demands. However, there is a general trend both at mobile and IoT level to offer computing services at the edge of the network leveraging on ultra/low-latency and high-bandwidth. For example, ETSI is defining the mobile edge computing (MEC) to offer applications such as video analytics, location services, mission-critical applications, augmented reality, optimized local content distribution and data caching, that can be considered as VNFs. Thus, it is required to dynamically allocate computing and storage resources to flexibly deploy VNFs in multiple DCs, and to provide the required connectivity between DCs with Quality of Service (QoS). Additionally, another main requirement is to offer network slices existing in parallel and isolated for different tenants (e.g., vertical industries, virtual operators) in order to deliver the tenant-specific requirements (e.g, security, latency, resiliency, bandwidth) [3].

To meet the above transport and service requirements, this paper presents a converged fixed-mobile access-metro optical network with programmable and elastic optical systems and distributed datacenters for cloud and edge computing. Additionally, this paper presents a service platform to provide efficient end-to-end resource and service orchestration based on reference architectures such as the ONF Software Defined Networking (SDN) and ETSI NFV standards.

converged fixed mobile fig1

Figure 1: Converged fixed-mobile access-metro optical network with unified SDN/NFV control framework

2. Elastic optical access and transport 

Fig. 1 shows the scheme of the network concept proposed. There, the COs are connected to the edge nodes (ENs), where BSs are located, by means of a passive optical network (PON) scheme. In order to deliver fixed access services to the users, the CO hosts the corresponding optical line terminals (OLTs) and aggregation subsystems. Interestingly, selected mobile x-haul signals can be multiplexed/demultiplexed in wavelength at the CO and transparently routed to another node of the metro/core network for further processing [4]. A PON scheme is envisioned as external plant in order to leverage the existing optical access infrastructure (e.g. GPON, NGPON1). By following this approach, the entire C-band is available in the majority of deployments. Therefore, a wavelength overlay of channels can be envisioned for providing C-RAN services over the exiting fixed access infrastructure (shared with fixed users) while following the elastic networking paradigm [4]. Additionally, when following the specifications of NGPON2 [5], virtual point-to-point links can be established by means of wavelength division multiplexing (WDM). These channels could be assigned to different ENs and/or services. Nevertheless, NGPON2 envisions also a high-speed residential access service employing time and wavelength division multiplexing (TWDM), where part of the C-band is used for downstream. Therefore, a careful analysis should be performed for the specific deployments of NGPON2. In terms of network architecture (shown in Fig. 1), a common power-splitting tree can be envisioned as a general case. In case of pursuing NGPON2 compatibility, different options can be envisioned. An interesting example can be including an intermediate WDM distribution stage in order to implement a hybrid wavelength-switched/-routed PON (as shown in Fig.1).

Additionally, the proposed network architecture can envision the gradual upgrade of some network parts (e.g. feeder) in order to include spatial division multiplexing (SDM) for further increasing the network capacity. Therefore, the spatial diversity obtained, in combination with WDM, would enable a fronthaul/backhaul infrastructure with unique 2-dimensional (2D) properties. A first approach for SDM can be based on bundles of standard single-mode fibers (SSMFs), since cables deployed in the field typically have a loose-tube design containing several fibers [1]. Nevertheless, a longer-term solution can rely on multicore fibers (MCFs), providing a compact parallel transmission medium.

By assuming the introduction of a flexible functional split, bandwidth and latency requirements are reduced, enabling the use of statistical multplexing. Therefore, cost-effective Ethernet can be employed to provide flexible allocation of capacity to the high number of endpoints and users in ultra-dense scenarios connected through C-RAN and fixed technologies. In order to allow aggregation and switching of flows including quality of service (QoS) at the transport level, the COs and ENs are expanded with Carrier Ethernet switches.

At the CO/OLT, programmable sliceable bandwidth/bitrate variable transceivers (S-BVTs) are used for concurrently serving different ENs at variable capacity. These S-BVTs can deliver multiple flows/slices where each can be independently configured by the control plane. At the other end of the network, each EN has a programmable BVT (non-sliceable) at the optical network terminal (ONT). The (S-)BVTs can be remotely configured by the control plane, for an optimal management of the network resources [6]. The parameters to be configured at each (S-)BVT include wavelength, spectral occupancy and capacity per flow. So, the (S-)BVTs deliver data flows with variable spectral occupancy and rate, according to the network and path conditions. Consequently, this solution is specifically tailored mobile midhaul, enabling the optimal management of different functional splits, while being also well-fitted for mobile fronthaul/backhaul.

Among all the options for implementing the (S-)BVTs, those based on DD orthogonal frequency division multiplexing (DD-OFDM) are the most attractive. In fact, these transceivers can be ad hoc configured for achieving a certain reach and/or coping with a targeted data rate adopting low complex optoelectronic subsystems [6].

3. Multi-tenant SDN/NFV control and orchestration 

The considered SDN/NFV control and orchestration system provides NFV network services and network slicing services. It is deployed on top of the end-to-end infrastructure shown in Fig. 1, composed of multi-layer (packet/optical) networks and multiple NFV infrastructure point of presence (NFVI-PoP) at the edge and core of the network. An NFVI-PoP is a set of computing, storage and network resources that provides processing, storage and connectivity to VNFs through the virtualization layer (e.g. hypervisor). It is deployed in micro-DCs in the edge nodes, small-DCs in the COs, and core-DCs in the core network. The ETSI NFV management and orchestration (MANO) architectural framework [7] identifies three functional blocks; virtualized infrastructure manager / WAN infrastructure manager (VIM/WIM), NFV orchestrator (NFVO) and VNF manager (VNFM).

The VIM is responsible for controlling and managing the NFVI-PoP’s virtualized compute, storage and networking resources, whilst the WIM is used to establish connectivity between NFVI-PoP’s. The VIM is commonly implemented using a cloud controller based on OpenStack. It interfaces with the NFVO/VNFM reference implementations using the OpenStack API. OpenStack enables to segregate the resources into availability zones for different tenants and to instantiate the creation/ migration/ deletion of VMs and CTs (computing service), storage of disk images (image service), and the management of the VM/CT’s network interfaces and network connectivity (networking service). The WIM can be performed by dedicated Transport SDN controllers (e.g. OpenDaylight, ONOS, Ryu) in charge of managing the packet and optical technologies. However, the main limitation of this approach is that currently the interface between the NFVO and the WIM is not widely implemented and still lacking maturity [8]

The VNFM is responsible for the lifecycle management of VNF instances, and the NFVO has two main responsibilities; the orchestration of NFV infrastructure resources across multiple VIMs and WIMs (resource orchestration) and the lifecycle management of network services (network service orchestration). The network service orchestration is responsible to coordinate groups of VNF instances that jointly realize a more complex function (e.g. service function chaining), including joint instantiation and configuration of VNFs and the required connections between different VNFs [9]. The NFVO and VNFMs are typically implemented together in reference software implementations such as open source MANO (OSM), ONAP or SONATA.

Finally, a Network Slice Manager (NSM) is deployed on top of the NFVO. The NSM is responsible of the lifecycle management of the network slices. Network slicing extends related concepts such as ETSI network services by defining a network slice instance as one network service instance or a concatenation of network service instances. The NSM leverages the NFV MANO to provide the network services associated to a slice and fulfilling its deployment requirements (e.g, security, latency, resiliency, bandwidth). The MSM is not supported in the current NFV MANO implementations, and it relies on proprietary extensions.

4. Conclusion 

5G is targeting a converged x-haul (fronthaul/midhaul/backhaul) network and cloud infrastructure to offer end-to-end services. To this end, it is required to move from the traditional overlay of heterogeneous and independent networks to a novel architecture integrating both mobile and fixed transport networks. This paper has presented a converged fixed-mobile access-metro optical network by integrating the recent advances in flexible and programmable optical device technologies, together with the emerging SDN/NFV control and orchestration paradigm.


Work supported by EC H2020 BLUESPACE (762055) and the Spanish DESTELLO (TEC2015-69256-R) projects.


  1. A. Girard, FTTxPon technology and testing, EXFO Electro-Optical Engineering Inc, 2005
  2. Chih-Lin I, Han Li, Jouni Korhonen, Jinri Huang, Jinri Huang, RAN Revolution with NGFI (xhaul) for 5G, Journal of Lightwave Technology, DOI: 10.1109/JLT.2017.2764924
  3. 5GPPP white paper, the 5G Infrastructure Public Private Partnership: the next generation of communication networks and services, March 2015.
  4. J. M. Fabrega et al., “Experimental Validation of a Converged Metro Architecture for Transparent Mobile Front-/Back-Haul Traffic Delivery using SDN-enabled Sliceable Bitrate Variable Transceivers,” in Proc. of ECOC 2017, paper M.2.A.5
  5. D. Nesset, "NG-PON2 Technology and Standards," in Journal of Lightwave Technology, vol. 33, no. 5, pp. 1136-1143, Mar. 2015.
  6. M. Svaluto Moreolo et al. “SDN-Enabled Sliceable BVT Based on Multicarrier Technology for Multiflow Rate/Distance and Grid Adaptation,”in Journal of Lightwave Technology, vol. 34, no. 6, pp. 1516-1522, Feb. 2016
  7. Network Functions Virtualisation (NFV); Management and Orchestration, ETSI GS NFV-MAN 001 v.1.1.1, (2014-12).
  8. Raul Muñoz, Ricard Vilalta, Ramon Casellas, Arturo Mayoral, Ricardo Martínez, Integrating Optical Transport Network Testbeds and Cloud Platforms to Enable End-to-End 5G and IoT Services, in Proc. of ICTON 2017.
  9. R. Casellas, R. Muñoz, R. Vilalta, R. Martínez, Orchestration of IT/Cloud and Networks: From Inter-DC Interconnection to SDN/NFV 5G Services , in Proceedings of the Optical Networks Design and Modelling (ONDM2016) conference, May 2016.



Raul Muñoz (SM’12) graduated in Telecommunications Engineering in 2001 and received a Ph.D. degree in Telecommunications in 2005, both from the Universitat Politècnica de Catalunya (UPC), Spain. Currently, he is Head of the Optical Network and System Department. Since 2000, he has participated in over 35 R&D projects funded by the Spanish and EC’s Framework Programmes (H2020, FP7, FP6 and FP5), as well as industrial contracts. He has been Project Coordinator of 5 Spanish projects, the coordinated EU-Japan FP7-ICT STRAUSS project (608528), and the H2020-MSCA-ITN ONFIRE project (765275). He has published over 60 journal papers and 200 international conference papers.



Josep M. Fabrega (S’05-M’10-SM’17) received his BSc, MSc and PhD degrees in telecommunications engineering from UPC-BarcelonaTech, Barcelona, Spain, in 2002, 2006 and 2010, respectively. Currently he is a Senior Researcher in the Optical Networks and Systems Department of CTTC, Castelldefels, Spain.  Since 2004, he has been actively involved in 22 public and industrial projects. He is the author/co-author of more than 100 papers, including 2 patents. His research interests include optical communication systems and signal delivery over novel optical network architectures. Dr. Fabrega is an IEEE Senior Member and received the EuroFOS best student research award in 2010.



Ricard Vilalta (M’13, SM’17) graduated in telecommunications engineering in 2007 and received a Ph.D. degree in telecommunications in 2013, both from the Universitat Politècnica de Catalunya (UPC), Spain. Ricard Vilalta is senior researcher at CTTC, in the Optical Networks and Systems Department. He is an active member of ETSI, IETF and ONF standardization bodies. His research is focused on SDN/NFV, Network Virtualization and Network Orchestration. He has been involved in several international, EU, national and industrial research projects. He has also authored and co-authored more than 180 journals, conference papers and invited talks.


Moreolo sized

Michela Svaluto Moreolo (S'04-A'08-SM'13) received the M.Sc. degree in Electronics Engineering and the Ph.D. degree in Telecommunications Engineering from University Roma Tre, Rome, Italy, in 2003 and 2007, respectively. She currently is a Senior Researcher and the Coordinator of the Optical Transmission and Subsystems research line within the Optical Networks and Systems Department, at the Centre Tecnològic de Telecomunicacions de Catalunya (CTTC), Castelldefels, Spain. She also serves as member of the CTTC Management Team, with the role of Project Management Coordinator. Her research interest areas include advanced transmission technologies and software-defined systems for future optical networks.


casellas sizedRamon Casellas (M'09, SM'12) graduated in telecommunications engineering in by the UPC-BarcelonaTech and ENST Telecom Paristech (1999). He worked as an undergraduate researcher at France Telecom R&D and British Telecom Labs, and completed a Ph.D. in 2002 at ENST, working as an associate professor. He joined CTTC in 2006, working in international and technology transfer research projects. His research interests include network control and management, traffic engineering, GMPLS/PCE, SDN and NFV aapers, 4 IETF RFCs and 4 book chapters.



Laia Nadal  (S’10) obtained her MSc Telecommunication Engineering degree July 2010 and the Master of Research on Information and communication Technologies in 2012.  She received her PhD degree in November 2014.  In 2010, she was awarded with the FPI grant from the Spanish Ministry of Economy and Competitiveness (MINECO) to perform her PhD in the CTTC. From May to August 2013 she was a Visiting Ph.D. Scholar in ADVA Optical Networking (Germany). She currently is a Researcher of the Communication Networks Division. Her research interests include signal processing and advance modulation formats for optical communication systems.



Ricardo Martínez (SM’14) received an M.Sc. degree in 2002 and a Ph.D. degree in 2007, both in telecommunications engineering, from the UPC–BarcelonaTech University, Spain. He has been actively involved in several EU public-funded and industrial technology transfer projects. Since 2013, he is Senior Researcher in the Communication Networks Division at CTTC in Castelldefels, Spain. His research interests include control and orchestration architectures for heterogeneous and integrated network and cloud infrastructures along with advanced mechanisms and algorithms for provisioning and recovering of quality-enabled services.



Editor: Rod Waterhouse

Robero Sabella, Ericsson

IEEE 5G Tech Focus: Volume 2, Number 2, May 2018 


Photonic technology will play a key role in 5G networks in different contexts. In 5G transport it will allow the transmission and routing of huge amounts of data traffic at an acceptable cost and the transformation of the radio access network. In data center, photonic interconnect and switching will allow the realization of a new architecture able to strongly reduce the energy consumption while providing a high level of flexibility in resource utilization.  In future hardware platforms, photonic chip-to-chip interconnect will allow a significant increase of bandwidth density leading to dramatically scaled up global capacity of those platforms. Integrated photonics will be a key technology to realize components and modules at the right costs, while greatly reducing energy consumption and footprint.

1. Introduction 

The evolution of mobile networks towards 5G will really enable the concept of a world globally connected and create significant opportunities for industry and society, giving every person and every industry the possibility to empower to reach their full potential. If in the last couple of generations, the mobile network evolution (i.e. 3G and 4G) allowed the mobile broadband experience, 5G will enable a global information exchange infrastructure with potentially unlimited access to information and sharing of data anywhere at any time.

A plethora of new services have been identified for 5G [1], all concerning the digital transformation of industry and society. Each new type of service, such as massive machine type communications (mMTC), critical machine type communications (cMTC) and extreme mobile broadband (eMBB) has its own set of requirements that must be fulfilled and its own business model. Since building service specific networks is not affordable, this means having one telecom infrastructure serving all possible types of services and able to support a wide range of requirements and capabilities, such as very high traffic capacity, high data rates, very low latency, massive number of devices (and very low device energy consumption), ultra-high reliability and availability. In a few words, the network will have to be flexible and scalable, to allow the network operator to accomplish the required investments for deploying the infrastructure and to evolve it when required with incremental and acceptable costs.

In particular, the expected huge traffic growth as well as a significant reduction of latency dictated by cMTC services will require a substantial transformation of the radio access networks (RAN) and, consequently, imposes a rethinking of the underlying transport network. As a second example, the expected 100-fold increase of the number of connected radio sites per area unit in the 5G RAN, together with the pervasiveness of mMTC devices, each one generating a low amount of traffic, calls for more efficient aggregation policies and transport networks topologies. 

The realization of such “universal” 5G network infrastructure will highly benefit from advanced photonic technologies to fulfill those requirements. Photonics can in fact allow low cost transmission and switching systems in different segments of the network, simplifying the architecture of some of those systems while performing better than electronics some key features, as described in the following sections.

2. Photonics for 5G Transport

The use of photonic technologies found extensive application, so far, in the long distance and metro transport systems and in Passive Optical Network (PON)-based access systems. This is sketched in the upper side of Figure 1. Fiber optic transmission links became commercially available in the second half of 80s and formed the so-called photonic layer of PDH (plesiochronous digital hierarchy) networks first and SDH/SONET (synchronous digital hierarchy), in Europe/North America later then. The advent of optical amplifiers in the 90s has strongly pushed the deployment of optical transmission systems over ever-increasing capacity (from some hundreds Mbit/s to 2.5, 10 and 100Gbit/s) and distance (from several tens of Km up to hundreds and thousands Km) to enable a dramatic fall of the cost per transmitted bit. Then the advent of optical switching devices, mostly based on WSS (wavelength selective switch) technology [2], has allowed further cost saving, due to: reduction of the number of optical-to-electrical-to optical (OEO) regenerating sites; possibility of rerouting individual optical channels in a reconfigurable mesh topology; implementation of costs effective protection schemes. More, optical switches cooperate and offload work of the digital cross-connects [3], whatever based on SDH, optical transport network (OTN) or packet technologies. In that way, the optical layer consists both of optical transmission lines as well as optical cross-connect (OXC) or reconfigurable optical add-drop multiplexer (ROADM). The evolution of packet switching nodes increasingly integrated with optical switching systems [4] has led to the evolution of the packet-over-optical transport nodes which found application in long distance, metro-regional and eventually metro-access networks. A multi-layer control and management system allows to simultaneously handle photonic and electrical switches in order to smartly route traffic according to traffic load conditions and implement protection and restoration paths for network resilience. In the access part of the network, the most deployed optical networks are the PONs, mostly based on Gigabit PON (GPON) and Ethernet PON (EPON) technology [5].

All those systems were (and still are) based on discrete photonic components and modules. The advent of 5G networks will lead to a dramatic increase of capacity requirements and a complexification of network topology as depicted in the lower part of Figure 1. The capacity will increase at least one order of magnitude in each segment. Just to make an example, feeding a 5G antenna based on massive MIMO will require to easily provide 100G at the cell site! A clear consequence of that is the true need to cut down correspondingly the cost of photonic transmission. In addition, as a consequence of the increase of the number of antenna elements and their transmission speed, there is an increasing requirement to cut the energy consumption and to reduce the footprint.

To accomplish all of that it is not possible to leverage on learning curve effects induced by higher volumes: new photonic technologies are needed.

One of the key technologies is integrated photonics. As happened with microelectronics, integration is the way to increase the system complexity without proportionally increasing the cost. Section 6 will briefly discuss the most relevant integrated photonics technologies. To better highlight the role of photonics, it is important first to highlight the significant changes in the transport architecture of 5G networks.


Figure 1: Transport network evolution towards 5G. 

3. 5G transport network artchitecture and photonic systems 

A relevant change is represented by the evolution of the radio access network and, specifically, by the transformation of the radio base station (RBS). Figure 2 shows the main steps of that transformation. A base station essentially consists of a baseband unit (BBU) and a radio unit (RU). The former includes all processing functions performed on the baseband signal, while the latter works on the radio frequency (RF) signal, and contains the antenna element, the RF power and low noise amplifiers, and the circuitry for digital-to-analog and analog-to-digital conversion of the downlink and uplink signals, respectively. In the traditional monolithic implementation, both BBU and RU are integrated in the same rack and connected via an RF cable. Subsequently, the RBS was split so that one BBU handles a certain number of remote RUs (RRUs), saving equipment cost. This transformation simplifies the deployment because the RRUs are simpler to install and configure, so reducing the operational expenditures, and allows a better coordination among RRUs connected to the same BBU. The typical distance between BBU and RRU is of the order of some hundred meters up to few kilometers.

To allow that transformation, it was necessary to introduce a new type of interface, named fronthaul, and related communication protocols. The most common one is named CPRI (common public radio interface) [6], based on a frame able to carry digitized IQ antenna samples while respecting tight requirements in terms of clock frequency accuracy, latency and synchronization of data in uplink and downlink. That interface can adapt to any radio standard but is bandwidth angry. For instance, to carry 40 MHz of radio bandwidth, corresponding to about 150 Mbit/s of true traffic, results to 2.5 Gbit/s CPRI data rate. For this reason, the new 5G radio will introduce new fronthaul interfaces, based on a different split of functions between BBU and RRUs.

Photonics for 5G Fig2

Figure 2: Radio access network evolution. 


A second step of transformation was the introduction of the centralized RAN (C-RAN).  In a C-RAN, the packet processing features asynchronous to the Hybrid Automatic-Repeat-Request (HARQ) loop, such as the Packet Data Convergence Protocol (PDCP) are centralized, as well as most of the Radio Control Functions (RCF), which are in charge of the load sharing among system areas and different radio technologies, the policies to control the schedulers in baseband and packet processing functions, the negotiation of QoS, etc. The centralization of those functions allows network operators to simplify their network architecture and management and to reduce the number of sites to lead to a further cost reduction especially in terms of operational expenditures. Packet processing and control functions can eventually be virtualized on generic purpose processors (GPPs), for example hosted in a data center, leading to the concept of cloud RAN. Even time critical baseband processing functions (BBFs) can be centralized but virtualization is more critical in this case so that they are more suitable for specific purpose processors (SPPs). Depending on the time sensitivity of the fronthaul interface between RRU and BBU, the maximum distance between RRU and BBU ranges from few kilometers up to few tens of kilometers.

All these transformations of the RBS and of the RAN lead to important changes in transport network. Probably, the most important one is that fronthaul, which was introduced as a point-to-point link between one BBU and one RRU, becomes a new transport segment with its peculiar requirements, distinguished by the backhaul segment responsible for the communication between the RBS and the rest of the network up to the mobile core network. Backhaul networks usually consist of aggregation nodes and links based on Ethernet transmission frames and packet switches (either Ethernet switches or MPLS/IP routers).

Fronthaul network instead, having to fulfill the tight requirements specified above, requires new architecture, nodes, and related photonic component and modules.

4. Photonics for data centers 

Data centers (DCs) are the cornerstone of current social networks and are key elements of future 5G networks.  They shall sustain the huge increase of network traffic while being increasingly green (i.e. consume less and less energy). The architecture of data centers is evolving in the last decade, passing from a hierarchical to a flat architecture [7], in which a huge number of servers must be connected to each other and to storage elements, besides being connected towards the outside world. Photonics is already playing a relevant role in DCs through a massive use of optical interconnections (basically point-to-point links). The evolution towards flat architectures will eliminate a huge number of OE/EO converting elements so that, besides photonic interconnect, photonic switching will emerge as a key technology [2,3,8,9]. If nowadays there is an internal packet aggregation interconnect network consisting of packet switches, in the future photonic switching could offload part of that work by introducing a given amount of circuit switching, for example to route long-lasting data flows that are most of internal data traffic volumes [4,10]. In this way the long lasting data flows are photonic switched while all the other are individually (packet-by-packet) switched in the electrical domain. The offloading of packet switches work also leads to improvement in the performance of short-lasting flows routing. The main benefit of the photonic switches is a dramatic reduction of both energy consumption and latency, while keeping the advantages of the CMOS scalable technology used for electrical packet switching in ensuring an ever-increasing processing capacity. Photonic switching can also provide an increased flexibility in the intra-DC interconnection among servers and storage elements to optimize the resources utilization. Nowadays there are static optical shuffles that are responsible for that function. Instead, a flexible and reconfigurable optical data center could provide a coordinated control of network resources and the capability to allocate dynamically the network capacity. This is made possible by re-applying the concept of SDN control and network function virtualization in the DC domain, in conjunction with a flexible photonic switched data plane.

Photonic switches suitable for those applications need to be highly integrated, low-cost, low-footprint, and high radix (64x64 or above). Silicon photonics is the most promising technology for that, and relevant examples are [11].

5. Photonic interconnect for future HW platforms 

The always increasing traffic to be managed by telecom networks will require not only increasingly higher transmission capacity but also a huge increase of processing capabilities in different nodes like data centers, baseband processing units and so forth. This means that the corresponding hardware platforms will have to scale up accordingly. The Moore Law contributes to match these requirements indicating a path for the increase of the capacity of integrated electronic circuits (e.g. ASICs, network processors etc.); but it is not enough since the demand of processing capability grows faster than the miniaturization possibilities foreseen by the Moore Law. Thus, parallelization of ASICs is necessary, as well as the increase the data speed at the I/O ports. This means that if on one hand the processing capability of a single chip will increase, on the other hand there is a larger number of high speed interconnections allowing the interoperation of multiple ASICs on the same board (and among different boards). Since I/O pads and packages cannot scale enough, the transmission lines, able to interconnect each chip to each other, must work at higher bit rate. Unfortunately, the speed of the electric transmission lines in the board is going reach the upper bound, due to the frequency dependent loss that will soon become unacceptable. The only way to overcome this problem is to move towards photonic transmission lines on the board, whose losses are less dependent on bitrate and length. The use of such photonic onboard interconnect will allow to increase the bandwidth density (i.e. transmitted bit/s per mm2) of future harware platforms.

Practical photonics based solutions to achieve that are: the silicon interposer and the optical multi-chip module [12,13], and the starboard concept [13]. Figure 3 shows the Teraboard approach. The optical multi-chip module includes different integrated elements: a high capacity digital processor, a photonic array of transceivers, and an analog frontend to drive the photonic circuit and amplify the signals. In this way, the electrical interconnect is limited to very short transmission lines (1-2 cm max), while the photonic starboard accomplishes the photonic interconnect between different optical multi-chip modules. Such a starboard consists of a multi-layer glass block where many photonic waveguides are scribed and act as a photonic shuffle with extremely compact footprint and very low losses.

Photonics for 5G Fig3a

Photonics for 5G Fig3b

Figure 3: Top picture represents the optical multi-chip module. Bottom picture shows the starboard interconnecting two optical multi-chip modules.

6. Integrated photonics for 5G networks 

As it has largely been experimented in tens of years in microelectronics, integration allows putting more and more functions and circuits on the same chip, leading to significantly lower assembly and test cost, besides a reduction of footprint and energy given by the miniaturization process. Of course the total cost of the component will come dependent on the yield of the fabrication process. In photonics, the basic technology for the devices is the InP, since lasers, photonic amplifiers and photodetectors are based on alloys III-V (e.g. InGaAsP heterostructures confined by InP). This because InP is a direct bandgap material able to easily generate and amplify light. Electronic elements can be realized as well with that technology. There are already commercial products based on InP photonic integrated circuits, like monolithically integrated multi-wavelength transceivers working up to 100Gbit/s [14]. However, the InP process technology never reached the performance of Silicon technology and thus the fabrication yield is low in comparison with CMOS technology. This limits the number of functions that can be integrated in a monolithic InP chip. Instead the well-developed Silicon process infrastructure, matured in many decades, allowed the implementation of very large scale integration system-on-chip and led to the development of highly integrated CMOS devices. If light generation and amplification cannot be achieved in Silicon, all the other photonic functions can be realized instead, such as modulators, detectors (Germanium monolithically integrated in Silicon), waveguides, de-multiplexers, power splitter etc. In addition, the high index contrast of Silicon enables the realization of more confined waveguides and miniaturized circuits (with respect to InP), and the tight integration with the electronics can be realized on the same chip area. Although the level of miniaturization cannot be of the same level as in the electronics, because the size of photonic elements and circuits is quite large in comparison to the size of a single transistor, it is still significant. For instance, in [15] was reported an integrated photonic system on chip accomplishing something like 1000 features in a few square millimeters device.

In summary, a complete photonic integrated circuit will need some InP based elements (i.e. lasers and semiconductor optical amplifiers) to be integrated with a Silicon chip through some kind of techniques, such as flip-chip [16], evanescent coupling [17] and template-assisted bonding [18].

Silicon photonics is the basic technology for many of the photonic components and modules mentioned in this paper: integrated transceivers, photonic switches for transport and for data centers, photonic interconnects for future HW platforms, as well as to accomplish some optical feature in radio sub-systems such as phase shifters, ultra-high frequency carrier generation.


The author wishes to thank Fabio Cavaliere, Paola Iovanna, and Francesco Testa for useful discussions.


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sabella sized Roberto Sabella (M’78–SM’81–F’87) is the leader of Optical Systems unit of Ericsson Research, based in Pisa, Italy, and Montreal, Canada. His expertise covers several areas of telecom networks, such as packet-optical transport, optical solutions for mobile backhaul and fronthaul, and photonics technologies for radio and data centers. He has authored more than 150 papers published on international journals, magazines, and conferences, two books on optical communications, and holds more than 30 patents. He was adjunct professor of telecom systems at the Sapienza University of Rome. He is a senior member of IEEE and has guest edited many special issues in several IEEE journals and magazines. He holds the “laurea degree” in electronic engineering from the University of Rome “La Sapienza”, Italy


Editor: Rod Waterhouse

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