LiFi High Speed Wireless Networking Using Nano-Metre Waves Professor Harald Haas

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1 LiFi High Speed Wireless Networking Using Nano-Metre Waves Professor Harald Haas

2 Energy harvesting Arms, Legs, Voice Action / Apps / Robotics Nervous Connectivity System Big data / data analytics / AI Brain Data/Signal processing Nervous Connectivity System Senses Sensors SMART-X Environments, e.g., manufacturing, cities, homes, cars, bodies..

3 Spectrum Crunch In 20 years (6G?), this means 12,000 bandwidth Winzer, Neilson, From Scaling Disparities to Integrated Parallelism: A Decathlon for a Decade, IEE/OSA JLT, MHz used for WiFi in 5 GHz band will need to become 6 THz RF is only 0.3 THz!! 20 times shortfall!

4 The small cell concept T. Cogalan and H. Haas, Why Would 5G Need Optical Wireless Communications?, PIMRC, October 2017.

5 Hitting physical limits in cellular RF communications under-seat deployments are now winning favor in all sorts of arenas for their ability to use human bodies to help build a more dense network Source: MSR, Stadium Tech Report, Q1/2016 5

6 The electromagnetic spectrum

7 Z. Wang, D. Tsonev, S. Videv and H. Haas, "On the Design of a Solar-Panel Receiver for Optical Wireless Communications With Simultaneous Energy Harvesting," JSAC, vol. 33, no. 8, pp , Aug. 2015

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11 Taxonomy Transmission speeds Ultra high 100 Gbps Very high 1 Gbps High 10 Mbps Low < 10 Mbps Duplex mode Full-duplex Half-duplex Simplex Static point-to-point (cable replacement) Very Low < 1 Mbps Short range < 10 cm Medium range 10 cm < 100 m Long range 100 m Range Mobile point-to-point Mobile, multiuser access and seamless handover Communication Mode

12 Elgala, H., Mesleh, R., and Haas, H., "Indoor Broadcasting via White LEDs and OFDM", IEEE Trans. Consum. Electron., vol. 55, no. 3, pp , Aug Non-linearity effects Intensity modulation (IM) of the optical carrier 1. Amplitude distortion 2. Upper clipping 3. Lower clipping

13 BER performance

14 Creating unipolar OFDM signals at the expense of spectrum efficiency o Generate two copies of a bipolar OFDM frame. o Reverse the signs in the second copy. o Remove all negative samples. o Concept known in literature as U-OFDM or as Flip-OFDM.

15 Unipolar / flip OFDM o Spectral efficiency is halved. o M-QAM DCO-OFDM should be compared to M2-QAM U-OFDM. o U-OFDM quickly loses energy efficiency with increasing spectral efficiency. o The same problem is observed in ACO-OFDM and PAM-DMT. Bipolar OFDM Bipolar Frame 1 Bipolar Frame 1 Bipolar Frame 1 U-OFDM Negative Frame 3 Positive Frame 3 Negative Frame 2 Positive Frame 2 NegativeFr ame 1 Positive Frame 1 N. Fernando, Y. Hong and E. Viterbo, "Flip-OFDM for Unipolar Communication Systems," IEEE Transactions on Communications, vol. 60, no. 12, pp , Dec/ D. Tsonev, S. Sinanovic and H. Haas, "Novel Unipolar Orthogonal Frequency Division Multiplexing (U-OFDM) for Optical Wireless," Vehicular Technology Conference (VTC Spring), Yokohama, 2012

16 Avoiding spectrum efficiency loss in unipolar OFDM o Subtraction removes interference from additional streams. U-OFDM Depth 3 N31 N31 N31 N31 U-OFDM Depth 2 N22 N22 P22 P22 U-OFDM Depth1 N14 P14 N13 P13 N12 P12 N P31 P31 P31 N21 N21 P21 P31 P21 P11 Maximum Depth Additional spectral efficiency [%] D. Tsonev, S. Videv and H. Haas, "Unlocking Spectral Efficiency in Intensity Modulation and Direct Detection Systems," JSAC, vol. 33, no. 9, pp , Sept

17 Electrical energy efficiency P elec = E{V( t)i(v( t))} o Voltage over LED probed and captured with the Oscilloscope o Bandwidth = 20 MHz o Constant bit loading o Pre-equalization

18 LED technologies / data rates 100 Data rate / Gbps Tsonev, et al., "Towards a 100 Gb/s visible light wireless access network," Opt. Express 23, (2015) Phosphor coated blue LED RGB LED GaN micro LED micro LED RGB laser LEDs LED technology

19 8 Gbps Mohamed Sufyan Islim, et al., Towards 10 Gb/s OFDM-based Visible Light Communication using a GaN Violet micro-led, Photonics Research, Gbps

20 LiFi ASICs Receiver LiFi MIMO ASIC Transmitter LiFi MIMO ASIC A. V. N. Jalajakumari et al., "High-Speed Integrated Digital to Light Converter for Short Range Visible Light Communication," in IEEE Photonics Technology Letters, vol. 29, no. 1, pp , 2017

21 Taking the 3 gigabit/s hurdle Tsonev, D, et al., A 3-Gb/s Single-LED OFDM-based Wireless VLC Link Using a Gallium Nitride μled, Photonics Technology Letters, vol. 26, no. 7, pp , 2014

22 Misconception number one: LoS

23 m 10 m 1.1 Gbps

24 Misconception: Interference from sunlight M. S. Islim, M. Safari, S. Videv, and H. Haas, A Proof-of-Concept of Outdoor Visible Light Communications in the presence of Sunlight, in LED professional Symposium - Expo 2016, Bregenz (Austria), September, 2016

25 Misconception: Interference from sunlight Dark Room Sunlight Irradiance Sunlight + Blue Filter Average SNR [db] S K [19.6 mm 2 ] SNR degradation compared to Dark Room 0% 29.33% 5.32% Data BER< 3.8e-3 [Mbps] Degradation of data rates compared to Dark Room. 0% 24.8% 4.7% S K [0.19 mm 2 ] Average SNR [db] SNR degradation compared to Dark Room 0% 11.6% 1.7% Data BER< 3.8e-3 [Mbps] M. S. Islim, M. Degradation Safari, S. Videv, of data and rates H. Haas, compared A Proof-of-Concept to Dark Room. of Outdoor 0% Visible Light 10.9% Communications 1.5% in the presence of Sunlight, in LED professional Symposium - Expo 2016, Bregenz (Austria), September, 2016

26 LiFi attocell networking Haas, H., High-speed wireless networking using visible light, SPIE Newsroom, Online: (invited) Haas, H., Wang, Y., and Yin, E., What is LiFi?, Journal of Lightwave Technology, vol. 3, iss. 8, April 2016 (invited) Tsonev, D.; Videv, S.; and Haas, H.; Light fidelity (Li-Fi): towards all-optical networking, Proc. SPIE 9007, Broadband Access Communication Technologies VIII, , 1 Feb. 2014

27 Rx FOV 85 - with lighting constraint 0.76 b/s/hz/m January, 2018

28 Rx FOV 45 - without lighting constraint 2.24 b/s/hz/m January, 2018

29 LiFi attocell networking Each light fixture serves as an access point (AP), and serves multiple users. Four types of deployment scenarios: (a) HEX; (b) Square; (c) HCPP; (d) PPP. C. Chen, et al., "Downlink Performance of Optical Attocell Networks," in JLT, 2016

30 Area data rate results Haas, et al., What is LiFi, JLT, 34 (6), , 2016

31 Joint transmission in VLC C. Chen, et al., "Fractional Frequency Reuse in DCO-OFDM-Based Optical Attocell Networks," in Journal of Lightwave Technology, vol. 33, no. 19, pp , Oct.1,

32 Simulation Setup Room size Modulation bandwidth Number of attocells 16 m x 9 m x3 m 20 MHz 13 Number of users 40 Benchmark systems: - Universal frequency reuse system ( reuse factor = 1 ) - Static reuse partitioning system ( reuse factor = 3 ) Simulated proposed system: - Joint transmission with frequency plan 1 - Joint transmission with frequency plan 2

33 Simulation results full frequency reuse

34 Simulation results joint transmission

35 The LiFi disruption The advent of LED lighting has shifted the business metric of the lighting world from $/bulb to $/lux. The additional energy management allows for building optimisation. Added communications and the increasing desire for infrastructure data means a convergence to $/bit.

36 IEEE LC Study Group topic interest groupstudy group task group standard drafts ballot & standard publishing Creation of LiFi alliance Alliance PoCs and interop testing Pre-standard devices available

37 IEEE Study Group

38 LiFi is real...

39 Source: telecoms.com Source: 123rf.com Electromagnetic spectrum is continuum Move from cm-wave to mm-wave to nm-wave!!