LDPC Tone Mapping for IEEE 802.11aj(45GHz) Date: September 13, 2019 Presenter: Haiming WANG Authors/contributors: Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Abstract This presentation describes LDPC tone mapping mechanism for IEEE 802.11aj(45GHz) Using the proposed LDPC tone mapping mechanism, the performance can be improved up to 4.2dB Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Introduction In 11n, interleaving is not needed for LDPC, since one 1944-bit LDPC codeword covers almost all streams and tones within an OFDM symbol. LDPC has an intrinsic pseudo-randomness property that protects against burst errors. In 11ac/ad/af, tone mapping is used for LDPC, since multiple streams and/or high MCSs lead to large NCBPS , so the coded bits from one LDPC codeword are transmitted only through a fraction of the tones when LCW < NCBPS , and the full frequency diversity would not be achieved. Notes: NCBPS means the number of code bits per OFDM symbols, LCW means the length of one LDPC codeword Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Introduction LDPC tone mapping distance in 11af, 11ad and 11ac by discretizing the burst errors, tone mapping can protect against burst errors, and overcome frequency selective fading better At the receiver, tone mapping can be implemented as part of the FFT block, with no additional delay LDPC tone mapping distance in 11af, 11ad and 11ac for 11ad, DTM is 2/3 for 16QAM/64QAM for 11ac, DTM is 4/6/6/9 for 20/40/80/160MHz for 11af, DTM is 8/9 for 2/4 segment operation Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Tone Mapping Mechanism(1/2) LDPC tone mapping could be used like 802.11ac, for each stream, map consecutive QAM symbols to data tones which are separated by at least DTM -1 other data tones where Notes: DTM means LDPC tone mapping distance, NSD means the total number of data subcarriers, NSS,u means the number of streams for user u, Nuser means the number of users Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Tone Mapping Mechanism(2/2) Using a block-interleaving matrix with DTM rows and NSD /DTM columns for every OFDM symbol at each stream, tone mapping can be implemented by writing row-wise and reading back column-wise Example: BW=540MHz, NSD =168, DTM =8, NSD /DTM =21, NSS =1 Write 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 Read Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Tone Mapping Distance(1/3) Procedure for choosing optimal DTM For each bandwidth, it would be desirable to have a DTM which is at least as large as , so that one LDPC codeword covers the full range of tones an integer divisor of the number of subcarriers, NSD constant over all rates within each bandwidth, so that the tone de-mapper can be implemented at Rx in the FFT block with fixed tone processing Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Tone Mapping Distance(2/3) Possible parameters For BW= 540MHz, NSD = 168, NSS= 4, Modulation= 64QAM, NCBPS/LCW= 168*6*4/672=6, so possible values for DTM are: 6,7,8,12,14,21,24,28,42,56,84 For BW= 1080MHz, NSD = 336, NSS= 4, Modulation= 64QAM, NCBPS/LCW= 336*6*4/672=12, so possible values for DTM are: 12,14,21,24,28,42,48,56,84,112,168 For each simulation, the best two DTM values are selected into optional parameter set, and the first/second element in the set is the best/second best parameter Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Tone Mapping Distance(3/3) For each BW, the intersection set of the optional parameter sets will be achieved For each BW, the element in intersection which leads to best performance for most simulation situations is proposed to be the optimal DTM Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Simulation Setup Channel model: Conference Room Number of distinguishable paths : 12 Packet length: 4096 bytes LDPC codeword length: 672bits Number of channel realizations: 5000 Simulation antennas: 1x1, 2x2, 4x4 for 1, 2, 4ss, respectively Modulation and code rate: {BPSK ½},{QPSK ½},{16QAM ½}, {64QAM ½} Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Simulation Results(1/2) Proposed optional parameter set For 540MHz For 1080MHz Parameters NSS=1 NSS=2 NSS=4 {QPSK ½} {6,7} {16QAM ½} {64QAM ½} {7,6} Parameters NSS=1 NSS=2 NSS=4 {QPSK ½} {12,14} {16QAM ½} {14,12} {64QAM ½} Notes: Since the performances of all DTM s for low-order modulations are very close, so their optional parameters sets could be ignored which are marked as “\” in the table. Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Simulation Results(2/2) Base on the results above, we can get the intersection for 540MHz and 1080MHz Appendix-A gives simulation results for DTM with bandwidth 540MHz Appendix-B gives simulation results for DTM with bandwidth 1080MHz BW 540MHz 1080MHz Intersection {6,7} {12,14} Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Conclusions LDPC tone mapping should be used for OFDM in IEEE 802.11aj (45GHz) Optimal DTM for LDPC tone mapping in 802.11aj BW 540MHz 1080MHz DTM 6 12 Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Reference [1] “11-10-1300-00-00ac-ldpc-for-11ac”, Jun Zheng et al. [2] “11-11-0428-00-00ac-proposed-correction-of-ldpc-tone-mapping-equation”, Hossein Taghavi et al. [3] “11-12-0839-00-00af-interleaver-parameters”, Ron Porat et al. [4] “Draft P802.11ad_D9.0” [5] “ Draft P802.11ac_D5.1” Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Simulation Results for 540MHz APPENDIX A: Simulation Results for 540MHz Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {6,7} 2 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {6,7} 2.2 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {7,6} 2 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {6,7} 0.7 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {6,7} 3 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {7,6} 2 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Simulation Results for 1080MHz APPENDIX B: Simulation Results for 1080MHz Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {14,12} 2 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {14,12} 4 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {12,14} 4 .2dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {14,12} 4 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {12,14} 1.8 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {12,14} 3.5 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Optional parameter set is {12,14} 3.5 dB gain Shiwen He, Haiming Wang, et al. (SEU/CWPAN)

Thanks for Your Attention! Shiwen He, Haiming Wang, et al. (SEU/CWPAN)