Symbol Interleaving for Single Carrier PHY in 802.11aj (45 GHz)

1. Symbol Interleaving for Single Carrier PHY in 802.11aj (45 GHz) Date: 2014-09-09 Presenter: Shiwen HE Authors/contributors:

2. Abstract This presentation describes symbol interleaving for SC PHY in 802.11aj (45 GHz). With the proposed symbol interleaving mechanism, the performance can be improved up to 2 dB.

3. In 802.11n/ac , bit interleaving is combined with BCC to protect against consecutive bits burst errors, especially caused by frequency selective fading. In 802.11ac,symbol interleaving is combined with LDPC, since without symbol interleaving, the full frequency diversity cannot be achieved if the length of one LDPC codeword is less than the number of code bits per OFDM symbol ( i.e. LCW < NCBPS ). Symbol interleaving would be used for SC PHY in 802.11aj (45 GHz), since LDPC has a stronger ability to correct discrete errors than BCC, so that bit interleaving is not necessary. symbol interleaving can protect against burst errors by discretizing these errors at the transmitter and correcting them at the receiver. Introduction

4. Symbol Interleaving Mechanism(1/2) • Block interleaving is proposed to use for SC PHY in 802.11aj (45 GHz). where Parameters：

5. Symbol Interleaving Mechanism(2/2) • Block interleaving would be implemented with a matrix of size • foreach block of each stream, by writing row-wise and reading • back column-wise. • Example: BW = 540 MHz,NDSPB= 256, NROW = 8, NSS = 1 Write Read

6. For each bandwidth, it would be desirable to have a NROW which is at least as large as , so that one LDPC codeword covers the whole block. an integer divisor of the number of symbols per block. Potential parameters For BW = 540MHz, Modulation = 64 QAM, NSS = 4, NCBPB = 256*6 = 1536, NCBPB/LCW = 1536*4/672 = 9.14, so the potential values for NROW are: 16, 32, 64, 128. For BW = 1080 MHz, Modulation = 64 QAM, NSS = 4, NCBPB = 512*6 = 3072, NCBPB/LCW = 3072*4/672 = 18.29, so the potential values for NROW are: 32, 64, 128, 256. Interleaving Depth NROW（1/2）

7. Interleaving Depth NROW（2/2） • For each simulation, the best two NROWvalues are found and selected into optional parameter set, and the first/second element in the optional parameter set corresponds to the best/second best parameter. • For eachbandwidth, the intersection set of the optional parameter sets will be achieved. • For eachbandwidth, the element in the intersection which leads to the best performance for most simulation situations is proposed to be the optimalNROW .

8. Simulation Setup • Packet length: 4096 bytes • Number of distinguishable paths: 18 • Simulation antennas: 1x1, 2x2, 4x4 for 1, 2, 4ss, respectively • Modulation and code rate: {QPSK ½},{16 QAM ½}, {64 QAM ½} • 5000 channel realizations for each PER curve

9. Simulation Results • Simulation results showthat using symbol interleaving for SC PHY can • achieve up to 2 dB gain. • Proposed optional parameter set for 540 MHz • Using the same method, optional parameter set for 1080 MHz can be • obtained. • Appendix-A gives simulation results for 540 MHz bandwidth. • Notes: Since the performances of all NROWfor low-order modulations are very close, their optional parameters sets could be ignored which are marked as “\” in the table.

10. Symbol interleaving should be used for SC PHY in 802.11aj (45 GHz). Interleaving depth NROWfor SC PHY in 802.11aj (45 GHz) Conclusions

11. Reference [1] “11-11-0048-00-00ac-interleaver-for-nss-greater-than-4”, Yonghong Qi et al. [2] “11-12-0839-00-00af-interleaver-parameters”,Ron Porat et al. [3]“Required Interleaving Depth in Rayleigh Fading Channels”, King Ip Chan et al. [4]“ Draft P802.11ac_D5.1”

12. APPENDIX A: Simulation Results for 540 MHz Bandwidth

13. Optional parameter set is {16,32} 0.3 dB gain

14. Optional parameter set is {16,32} 0.3 dB gain

15. Optional parameter set is {16,32} 0.2 dB gain

16. Optional parameter set is {16,32} 0.5 dB gain

17. Optional parameter set is {16,32} 1.5 dB gain

18. Optional parameter set is {16,64} 0.2 dB gain

19. 0.9 dB gain • Optional parameter set is {16,32}

20. 2 dB gain • Optional parameter set is {16,32}

21. Thanks for Your Attention.