IEEE Vienna 17 July 2019 802 11 Coexistence

IEEE Vienna, 17 July 2019 802. 11 Coexistence Workshop Performance Evaluation of Channel Access Mechanisms in 6 GHz Spectrum Jiayin Zhang (zhangjiayin@huawei. com) Weiwei Fan (fanweiwei 3@huawei. com) David Mazzarese (david. mazzarese@huawei. com) Mohamed Salem (Mohamed. Salem@huawei. com)

Contents • Background • Potential Access Mechanisms in 20 MHz operation bandwidth • Evaluation assumptions, methodologies and results • Narrow band vs. Wideband LBT in 6 GHz • Conclusions

Background • There are discussions to open 6 GHz for unlicensed usage in both USA and EU > In FCC, the potential spectrum is from 5. 925 GHz to 7. 125 GHz, further divided into 4 bands of UN-II-5/6/7/8. > In ETSI, new WI on 5. 925 GHz to 6. 425 GHz was approved in June 2019 by TC BRAN (BRAN(19)102016 r 2). • The 6 GHz unlicensed spectrum attracted interests from both IEEE 802. 11 and 3 GPP NR-U > 3 GPP NR-U in Release 16 will support operations in 6 GHz (RAN 1 freeze at the end of 2019). > IEEE 802. 11 ax extended design of 5 GHz into 6 GHz. The testing in WFA (Wi. Fi 6) for 6 GHz is expected in Jan 2021. > IEEE 802. 11 be will also support 6 GHz spectrum in the future. • In 3 GPP NR-U Rel-16 Study item and Work Item > The coexistence between NR-U and 802. 11 ax in 6 GHz spectrum were evaluated by several companies. The schemes defined in 5 GHz were the starting points. > The support of wideband LBT (>20 MHz) as well as narrow band LBT (per 20 MHz) was also discussed to simplify the implementation. 3

Potential Access Mechanisms in 6 GHz • Baseline: (existing scheme for 5 GHz LAA) > Scheme 1: 11 ax PD=-82 d. Bm, ED=-62 d. Bm; NR-U ED only=-72 d. Bm • Common ED threshold between 802. 11 ax and NR-U > Scheme 2: 11 ax PD=-82 d. Bm, ED=-82 d. Bm; NRU ED only=-82 d. Bm > Scheme 3: 11 ax PD=-82 d. Bm, ED=-72 d. Bm; NRU ED only=-72 d. Bm > Scheme 4: 11 ax PD=-82 d. Bm, ED=-62 d. Bm; NRU ED only=-62 d. Bm • Common preamble : > Scheme 5: - Common 11 a preamble (L-STF+L-LTF+L-SIG); - 11 ax/NRU PD=-82 d. Bm, ED=-62 d. Bm; - assuming – 4 d. B detection SINR of 11 a preamble > Scheme 6: - Common 11 ax preamble (L-STF+L-LTF+L-SIG+RL-SIG); - 11 ax/NRU PD=-82 d. Bm, ED=-62 d. Bm; - assuming – 7 d. B detection SINR of 11 ax preamble without auto-detection. 4

Evaluation assumptions and methodology in TR 38. 889 Common configurations Indoor scenario Carrier Frequency Carrier Channel Bandwidth Number of carriers Number of users per operator Channel Model BS/AP Tx Power UE/STA Tx Power BS/AP Antenna gain UE/STA Antenna gain BS/AP Noise Figure UE/STA Receiver Noise Figure UE receiver MIMO BS/AP antenna Array configuration UE/STA antenna Array configuration outdoor scenario 1/2 Traffic model Numerology MCOT/TXOP Response timing Max MCS Other 5 6 GHz 20 MHz baseline 1 Exactly 5 per g. NB per 20 MHz Indoor: NR In. H Mixed Office model for all links Outdoor: NR UMi street canyon for all links 23 d. Bm (total across all TX antennas) 18 d. Bm (total across all TX antennas) 0 d. Bi 5 d. B 9 d. B MMSE-IRC DL/UL MU MIMO + DL/UL OFDMA, ideal CSI/CQI feedback (M, N, P, Mg, Ng) = (1, 2, 2, 1, 1), d. H = d. V = 0. 5 λ Tx/Rx: (M, N, P, Mg, Ng) = (1, 1, 2, 1, 1), d. H = d. V = 0. 5 λ Use 36. 889 Table A. 1. 1. Note: Results based on the mixed traffic models can be used to determine the design. system specific configurations NR-U 802. 11 ax 60 k. Hz SCS + ~1. 2 us CP 78. 125 k. Hz SCS + 0. 8 us CP 8 ms 4 ms K 1 >= 0. 75 ms, K 2 >= 0. 75 ms 16 us SIFS NR LDPC with 256 QAM 802. 11 ac/ax LDPC with 256 QAM CC-HARQ, 1 switching point within MPDU: 1500 B MSDU + 14 B header a COT. RTS/CTS off; NAV on MAC header

Performance comparison with common ED • When one of operator #2 replace Wi-Fi AP with NR-U g. NB, the UPT of remaining Wi-Fi operator (#1) increased when common ED threshold is adopted by both Wi-Fi and NR-U. • In most cases, adopting common ED threshold of -62 d. Bm between Wi-Fi and NR-U could achieve best performance of mean and 5 th percentile UPT. Gain of Wi-Fi OP#1 when OP#2 replacing Wi. Fi AP with NR-U g. NB Common ED=-82 d. Bm (scheme 2) Common ED=-72 d. Bm (scheme 3) Common ED=-62 d. Bm (scheme 4) Mean UPT (Wi-Fi in coex) 3. 4% 21. 4% 31. 8% 5% UPT(Wi-Fi in coex) 3. 1% 29. 9% 73. 4% • The NR-U performance could also benefit from the increased common ED threshold in most cases Gain of NRU OP#2 in coex with Wi-Fi OP#1 (compared with scheme 1) Common ED=-82 d. Bm (scheme 2) Common ED=-72 d. Bm (scheme 3) Common ED=-62 d. Bm (scheme 4) Mean UPT (NR-U in coex) -11. 6% 0. 9% 7. 2% 5% UPT(NR-U in coex) -30. 8% 2. 1% 7. 6% Note: DL performance with single stream, medium traffic load in indoor scenario 6

Performance comparison with common preamble • 11 ax performance is degraded due to less spatial reuse opportunities when all NR-U bursts are treated same as Wi-Fi using -82 d. Bm PD level. Gain of 11 ax by introducing common preamble to NRU 11 a preamble 11 ax preamble Compared with scheme 1 Compared with scheme 4 Mean UPT (Wi-Fi in coex) -17. 2% -18. 4% -16. 9% -18. 2% 5% UPT(Wi-Fi in coex) -26. 9% -40. 9% -24. 6% -39. 1% • NR-U performance is also degraded because of less spatial reuse (PD=-82 d. Bm for all burst) and limited detection sensitivity of 11 a and 11 ax preamble. Gain of NR-U by introducing common preamble to NRU 11 a preamble 11 ax preamble Compared with scheme 1 Compared with scheme 4 Mean UPT (Wi-Fi in coex) -13. 0% -18. 8% -12. 7% -18. 5% 5% UPT(Wi-Fi in coex) -34. 8% -39. 4% -30. 9% -35. 8% Note: DL performance with single stream, medium traffic load in indoor scenario 7

Narrow band vs. Wideband LBT in 6 GHz • NR-U Rel-16 supports component carrier of at most 100 MHz, as NR in Rel-15. Multiple such carriers (inter/intra band) can be aggregated. • The use of 320 MHz channel bandwidth is also under discussion in 802. 11 be for higher peak throughput. • Transmitter should perform LBT at each Observation Slot of 9 μs on each of 20 MHz operation channel, assuming similar multi-carrier channel access defined in 5 GHz (option 1 in ETSI 301 893, or type A in 3 GPP TS 37. 213). The complexity is quite high when the operation bandwidth is wide. • Simplification can be achieved, if option 2 in ETSI 301 893 or type B in 3 GPP TS 37. 213 is adopted, at the cost of limitation on the channel bonding patterns. • Wi-Fi performs ED on P 20/S 40/S 80 hierarchically when 160 MHz operating bandwidth is configured. • Wideband LBT could simplify the implementation of wideband operation when it can be guaranteed that the channel is free of narrow band interference. > limiting usage of narrow band signal (20 MHz) on certain sub-band > By long/short term measurement and LBT bandwidth adaption. > FFS: ED threshold 8

Conclusions • Common ED threshold (e. g. -62 d. Bm) can benefit both 802. 11 ax and NR-U due to additional spatial reuse gain. • A common preamble and PD/ED threshold, such 11 a preamble with PD=-82 d. Bm and ED=-62 d. Bm, degrades performance of both NR-U and Wi-Fi as it prohibits spatial reuse • Wideband LBT is beneficial for system operating with wide bandwidth to simplify LBT implementation. • IEEE and 3 GPP should explore the possibility to mandate a minimum bandwidth larger than 20 MHz in greenfield 6 GHz spectrum 9

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Evaluation results – indoor scenario [TR 38. 889] (1 spatial stream) 11

Evaluation results – outdoor scenario 1 [TR 38. 889](1 spatial stream) 12

Evaluation results – outdoor scenario 2 [TR 38. 889] (1 spatial stream) 13

Evaluation results – indoor scenario [TR 38. 889] (<=4 spatial streams) 14

Evaluation results – outdoor scenario 1 [TR 38. 889] (<=4 spatial streams) 15

Evaluation results – outdoor scenario 2 [TR 38. 889] (<=4 spatial streams) 16