March 2019 doc IEEE 802 11 181957 r

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Experimental Study of NOMA/SOMA in Wi-Fi Date: 2019 -03 -11 Authors: Name Affiliation Evgeny Khorov IITP RAS Alexey Kureev IITP RAS Ilya Levitsky IITP RAS Address Phone Email khorov@iitp. ru Submission Slide 1 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Outline • • Motivation NOMA and SOMA brief introduction KPIs Theoretical results Testbed description November’ 18 results for NOMA (and short links) February’ 19 results for SOMA (and long links) Submission Slide 2 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Motivation In current networks, it is a typical situation when an AP serves several devices • located at different distances from the AP (thus having different channel attenuation) • having different traffic load. In this case, Non-orthogonal multiple access (NOMA) can be a promising solution to increase spectrum efficiency. This presentation considers theoretical and experimental results for DOWNLINK NOMA. [1] proposes SOMA, which is actually a specific case of NOMA (having no SIC). [1] doc. : IEEE 802. 11 -18/1462 r 0 SOMA for EHT Submission Slide 3 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Basic Idea of Downlink NOMA Power Traditional TDMA P P To STA 1 To STA 2 Different MCSs NOMA To STA 2 To STA 1 STA 2 AP STA 1 Submission Slide 4 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Signal Superposition TX side RX side Q STA 1 I STA 2 Submission Slide 5 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 A possible transmission process SIFS DIFS To STA 2 AP STA 1 To STA 1 ACK STA 2 Submission ACK Slide 6 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 KPI • Submission Slide 7 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 With SOMA, no SIC is needed AP STA 2 Gray-mapped superposed constellation Q STA 1 Q I BPSK STA 1 Q QPSK 1011 1001 0011 1010 1000 0010 I Q I STA 2 I 1110 1100 0110 1111 1101 0111 Result Can be considered as multiplexing + reflection of constellations Submission 8 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Theoretical Results for 11 a PHY 802. 11 a SNR 1 3 d. B SNR 2 19 d. B MCS TDMA 0 and 6 MCS NOMA 0 and 4 0. 85 Payload 1 K/4 K to align NOMA payloads Comments 1) Round Robin 1 K/1 K – Equal throughput for both STAs 2) Round Robin 1 K/4 K – Throughput for STA 1 goes down, Throughput for STA 2 is 4 times higher than for STA 1 3) Proportional fair 1 K/4 K – Equal channel time. Thrp for STA 1 even lower, Thrp for STA 2 even higher -> Max Geomeric Mean Thrp 4) NOMA 1 K/4 K – 92% gain in thrp for STA 1, small gain in thrp for STA 2, Overall gain +43% Submission Slide 9 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Trade-off between throughputs for STA 1 & STA 2 max average/total thrp is not a good target Proportional fair operation point Round Robin Operation point Submission Slide 10 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Testbed AP (SDR) Can be used with legacy off-the-shelf device! STA 2 (SDR) As NOMA device Full description: E. Khorov, A. Kureev, I. Levitsky. NOMA Testbed on Wi-Fi. //In Proc. of IEEE PIMRC, Bologna, Italy, 9 -12 September 2018 Evgeny Khorov (IITP RAS) Slide 11 STA 1 (Laptop) legacy device Submission

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 TX Implementation Source Data 1 Submission Data bytes to bits TX IQ Processing Encoder Modulator FFT Data 2 Data bytes to bits Encoder Modulator Slide 12 to RF +reflection Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 RX Implementation Demodulator & Decoder from RF RX IQ Processing Data 1 Demodulaor Decoder Bits to data bytes Data 2 Destination Decoder Demodulator Bits to data bytes weak signal is isolated here Always trying to separate SOMA packets If no SOMA, the following check fails: (NO additional “SOMA indication bits” used!) Reserved bit, tail bits, parity bits, N_SYM 1 ≥ N_SYM 2 Submission Slide 13 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Implementation PHY RX State machine for weak signal False IDLE Signal detected L-SIG decoding Done Reserved bit, tail bits, parity check passed & N_SYM 1 ≥ N_SYM 2 False True extracted Done FCS check passed True Frame decoding Frame received Submission Slide 14 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Minimal set of changes to the standard • Capabilities IE – Indicator that a device is able to decode a NOMA/SOMA frame – the other of NOMA/SOMA (optional) • The way how modulations are multiplexed – For example, Gray-mapped superposed constellation Submission Slide 15 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 NOVEMBER RESULTS Submission Slide 16 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Testbed. Experimental Setup AP (SDR) A legacy device is replaced with SDR to simplify gathering statistics STA 2 (SDR) As NOMA device In November experiments, we located devices in the same room, reduced TX power and used 30 d. B attenuators to model different channel conditions Submission Slide 17 STA 1 (SDR) As legacy device Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Evaluation. Reference Throughputs STA 1 Payload ~ 1 k. B STA 2 Payload ~ 2 k. B Different payloads are needed to make multiplexed frames of the same duration Submission Slide 18 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Testbed. Results NOMA Link 1 MCS 1 Link 2 MCS 3 STA 1 Payload ~ 1 k. B STA 2 Payload ~ 2 k. B x 1. 5 Obtained as the average throughput of STA 1 and STA 2, when each of them has 50% of channel time Submission Slide 19 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Balance between throughput for STA 1 & STA 2 Submission Slide 20 Evgeny Khorov (IITP RAS)

doc. : IEEE 802. 11 -18/1957 r 3 March 2019 FEBRUARY RESULTS (SOMA) Submission Slide 21 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Testbed. Experimental Setup AP (SDR) STA 2 (SDR) As NOMA device In February experiments, we located devices in separate rooms to provide different channel conditions for STA 1 and STA 2. Submission Slide 22 STA 1 (SDR) As legacy device Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Location of devices (AP) Now, the devices are located in different rooms and no attenuators are used Submission STA 1 STA 2 Slide 23 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Example of stats Submission Slide 24 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Testbed Results PF Link 1 MCS 1 Link 2 MCS 5 SOMA Link 1 MCS 1 Link 2 MCS 3 Twice lower because of fair sharing Submission x 1. 4 Slide 25 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 NOMA/SOMA Properties • Backward compatibility (STA 1 can be legacy) – Even if not standardized, any vendor can use NOMA/SOMA for transmission between its own devices, and at the same time transmit data to other devices. 1. Almost double throughput for the STA with poor channel (in case of fare resource allocation) OR 2. Manifold gain in throughput of the nearest STA (STA 2) while providing guaranteed throughput for the far STA (STA 1) 3. If devices are close to each other higher modulations are possible. Submission Slide 26 Evgeny Khorov (IITP RAS)

March 2019 doc. : IEEE 802. 11 -18/1957 r 3 Straw Poll Should NOMA/SOMA be considered as a possible solution for future 802. 11 standards? • Yes, for EHT • Yes, for another project • No • Need more info • Abstain Submission Slide 27 Evgeny Khorov (IITP RAS)