Different Channel Coding Options for MIMO-OFDM 802.11n 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Different Channel Coding Options for MIMO-OFDM 802.11n Ravi Mahadevappa, ravi@realtek-us.com Stephan ten Brink, stenbrink@realtek-us.com Realtek Semiconductors, Irvine, CA Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

Overview Simulation environment/assumptions Different channel codes January 2004 Overview Simulation environment/assumptions Different channel codes Comparison: Required SNR, selected cases Observations and recommendations Appendix: Rate/RX sensitivity tables for different channel coding options Ravi Mahadevappa, Stephan ten Brink, Realtek

Simulation Environment 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Simulation Environment 802.11a PHY simulation environment, plus Higher order QAM constellations Higher/lower channel code rates TX/RX diversity/MIMO OFDM Alamouti with MRC ZF detection and soft post processing Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

Likely 802.11n Transmitter Shown with 2 TX antennas channel encoder January 2004 Likely 802.11n Transmitter channel encoder Shown with 2 TX antennas Ravi Mahadevappa, Stephan ten Brink, Realtek

Likely 802.11n Receiver Shown with 2 RX antennas channel decoder January 2004 Likely 802.11n Receiver channel decoder Shown with 2 RX antennas Ravi Mahadevappa, Stephan ten Brink, Realtek

Simulation Assumptions 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Simulation Assumptions Perfect channel knowledge/synchronization Idealized multipath MIMO channel More optimistic than [3] Sub-channels independent; exponential decay, Trms = 60ns Quasi static (channel stays constant during one packet) Packet length: 1000 bits and 10000 bits 10dB noise figure (conservative [4]) 5dB implementation margin (conservative [4]) Not yet incorporated in results: Channel estimation Packet detection, synchronization foff estimation Clipping DAC/finite precision ADC Front-end filtering Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

Different Channel Codes January 2004 Different Channel Codes Convolutional code memory 6 (abbreviation CC6) Convolutional code memory 8 (CC8) Parallel concatenated code [9], UMTS turbo code memory 3 (PCC3), random bit interleaver (over packet), 8 iterations Serially concatenated code [10], inner memory 1, outer memory 2 code (SCC2), random bit interleaver (over packet), 15 iterations LDPCC, regular [11] (LDREG), random edge interleaver (over packet), 40 iterations (note: 1-Rate = dv/dc) Rate 1/2: variable node degree dv=3, check node degree dc=6; rate 3/4: dv=3, dc=12; rate 7/8: dv=3, dc=24 LDPCC, irregular [12] (LDIRR), random edge interleaver (over packet), 40 iterations dv,1=3 (89.74% of variable nodes), dv,2=4 (2.78%), dv,3=16 (7.48%); rate 1/2: dc=8; rate 3/4: dc=16; rate 7/8: dc=32 Ravi Mahadevappa, Stephan ten Brink, Realtek

Table C1, 802.11a, 1x1, different codes, AWGN, length 1000 bits January 2004 Table C1, 802.11a, 1x1, different codes, AWGN, length 1000 bits Required SNR at 10% PER Difference between various channel coding options is about 1-2dB Best: Turbo code of memory 3, PCC3 Worst: Convolutional code of memory 6, CC6 Memory 8 convolutional code CC8 gains about 0.5dB Ravi Mahadevappa, Stephan ten Brink, Realtek

Table C1, 802.11a, 1x1, AWGN, length 10000 bits January 2004 Table C1, 802.11a, 1x1, AWGN, length 10000 bits Longer block length: CC6, CC8 have worse PER by about 1dB: Code does not become stronger, but packet error prob. increases Longer block length: good for iterative decoding (stronger code) Differences between codes more pronounced for longer block length LDREG and LDIRR virtually identical for maxlog-decoding Ravi Mahadevappa, Stephan ten Brink, Realtek

Table C2, 802.11a, 1x1, fading, length 10000 bits January 2004 Table C2, 802.11a, 1x1, fading, length 10000 bits Trms=60ns Maxlog-decoding used for PCC3, SCC2 and LDREG In fading, CC8 gains about 1dB over CC6 PCC3 still best; gain of about 2-3.5dB over CC6 Ravi Mahadevappa, Stephan ten Brink, Realtek

Table C3, 802.11a, 2x3, AMRC, length 10000 bits January 2004 Table C3, 802.11a, 2x3, AMRC, length 10000 bits AMRC, Alamouti space/time block code [8] with max. ratio combining at receiver CC8 gains about 0.5dB over CC6 PCC3 still best; gain of about 2-3dB over CC6 SCC2 worse than PCC3; omitted in the following Ravi Mahadevappa, Stephan ten Brink, Realtek

Table C4, High-rate, 2x3, SMX, length 10000 bits January 2004 Table C4, High-rate, 2x3, SMX, length 10000 bits SMX, spatial multiplexing [6,7] Rate 7/8 PCC3 obtained by random puncturing of parity bits CC8 gains about 0.5-1dB over CC6 PCC3/LDPCC gain of about 2-3dB over CC6 for rate 3/4 PCC3/LDPCC gain of about 4dB over CC6 for rate 7/8 Ravi Mahadevappa, Stephan ten Brink, Realtek

2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Observations About 1-4dB gain possible with improved coding (LDPCC/PCC) for large block lengths CC8 gains about 0.5-1dB over CC6; simple to implement LDPCC similar performance as PCC3 Concatenated codes with iterative decoding (PCC3, LDPCC) yield best performance, but implementation complexity high Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

From “11-03-0845-01-000n-receiver-sensitivity-tables-mimo-ofdm.ppt” 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Recommendation Bandwidth 20MHz 40MHz From “11-03-0845-01-000n-receiver-sensitivity-tables-mimo-ofdm.ppt” SMX 2x3 3x4 Modulation 128QAM or higher 64QAM Code rate 7/8 3/4 Data rate >147Mbit/s 162Mbit/s 216Mbit/s Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

From “11-03-0845-01-000n-receiver-sensitivity-tables-mimo-ofdm.ppt” 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Recommendation Bandwidth 20MHz 40MHz From “11-03-0845-01-000n-receiver-sensitivity-tables-mimo-ofdm.ppt” SMX 2x3 3x4 Modulation 128QAM or higher 64QAM Code rate 7/8 3/4 Data rate >147Mbit/s 162Mbit/s 216Mbit/s From “11-04-0014-00-000n-diff-channel-codes-mimo-ofdm.ppt” (this doc.) Coding scheme CC6 New coding scheme PCC3 or LDPCC or CC8 (mandatory) CC8 (mandatory) PCC3 or LDPCC (optional) Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

Recommendation Bandwidth 20MHz 40MHz SMX 2x3 3x4 Modulation 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Recommendation Bandwidth 20MHz 40MHz From “11-03-0845-01-000n-receiver-sensitivity-tables-mimo-ofdm.ppt” SMX 2x3 3x4 Modulation 128QAM or higher 64QAM Code rate 7/8 3/4 Data rate >147Mbit/s 162Mbit/s 216Mbit/s From “11-04-0014-00-000n-diff-channel-codes-mimo-ofdm.ppt” (this doc.) Coding scheme CC6 New coding scheme PCC3 or LDPCC or CC8 (mandatory) CC8 (mandatory) PCC3 or LDPCC (optional) From “11-04-0013-00-000n-on-off-feedback-mimo-ofdm.ppt” Feedback Subchannel on/off-feedback or other forms (optional) Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

Some References January 2004 [1] J. M. Keenan, A. J. Motley, “Radio coverage in buildings”, British Telecom Technology Journal, vol. 8, no. 1, Jan. 1990, pp. 19-24 [2] J. Medbo, J.-E. Berg, “Simple and accurate path loss modeling at 5GHz in indoor environments with corridors”, Proc. VTC 2000, pp. 30-36 [3] J. P. Kermoal, L. Schumacher, K. I. Pedersen, P. E. Mogensen, F. Frederiksen, “A stochastic MIMO radio channel model with experimental validation”, IEEE Journ. Sel. Areas. Commun., vol. 20, no. 6, pp. 1211-1226, Aug. 2002 [4] IEEE Std 802.11a-1999, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, High-speed Physical Layer in the 5 GHz Band [5] J. H. Winters, J. Salz, R. D. Gitlin, “The impact of antenna diversity on the capacity of wireless communication systems”, IEEE Trans. Commun., vol. 42, no. 2/3/4, pp. 1740-1751, Feb./Mar./Apr. 1994 [6] G. J. Foschini, “Layered space-time architecture for wireless communication in a fading environment when using multi-element antennas”,Bell Labs. Tech. J., vol. 1, no. 2, pp. 41-59, 1996 [7] H. Sampath, S. Talwar, J. Tellado, V. Erceg, A. Paulraj, “A fourth-generation MIMO-OFDM broadband wireless system: Design, performance, and field trial results”, IEEE Commun. Mag., pp. 143-149, Sept. 2002 [8] S. M. Alamouti, “A simple transmit diversity technique for wireless communications”, IEEE J. on Select. Areas in Commun., vol. 16, pp. 1451-1458, Oct. 1998 [9] C. Berrou, A. Glavieux, P. Thitimajshima, “Near Shannon limit error-correcting coding and decoding: Turbo-codes”, in Proc. ICC, May 1993, pp. 1064-1070 [10] S. Benedetto, D. Divsalar, G. Montorsi, F. Pollara, “Serial concatenation of interleaved codes: Performance analysis, design and iterative decoding”, IEEE Trans. Inform. Theory, vol. 44, no. 3, pp. 909-926, May 1998 [11] R. G. Gallager, “Low-density parity-check codes”, IEEE Trans. Inform. Theory, vol. 8, pp. 21-28, Jan. 1962 [12] T. J. Richardson, A. Shokrollahi, R. L. Urbanke, “Design of capacity-approaching low-density parity-check codes”, IEEE Trans. Inform. Theory, vol. 47, no. 2, pp. 619-637, Feb. 2001 Ravi Mahadevappa, Stephan ten Brink, Realtek

Appendix Receiver sensitivity tables C1-C4 January 2004 Appendix Receiver sensitivity tables C1-C4 Abbreviations, diversity/MIMO modes: SEL: selection diversity at RX AMRC: Alamouti Space/Time [8] with MRC at RX SMX: spatial multiplexing (i.e. MIMO mode, [6,7]) Abbreviations, MIMO detection algorithms ZF: Zero Forcing with APP post processing Abbreviations, channel coding options CC6, CC8: convolutional codes of memory 6, 8 PCC3: parallel concatenated code (memory 3) SCC2: serially concatenated code (inner memory 1, outer memory 2) LDREG, LDIRR: regular, irregular low-density parity-check code (LDPCC) Ravi Mahadevappa, Stephan ten Brink, Realtek

Rate Table (C1) 802.11a, 1x1, Different Codes, AWGN January 2004 Rate Table (C1) 802.11a, 1x1, Different Codes, AWGN Data rate (Mbps) Constellation Code rate, code MIMO mode Bandwidth (MHz) simulation result: Required Es/N0 (time: Es/N0fr-0.9dB) [dB] (10% PER, 1000bits), (1%, 1000), (10%, 10000) RX sensitivity [dBm] (10% PER, NF=10dB, margin 5dB) 20MHz: (-174+73+10+5)dBm+Es/N0 (10% PER, 1000bits, maxlog) 6 BPSK 1/2, CC6 1x1 20 -1.0 -0.2 -87.0 1/2, CC8 -1.6 -0.8 -0.9 -87.6 1/2, PCC3 max/jac -2.5 / -2.8 max/jac -2.2 / -2.5 max/jac -2.6 / -3.0 -88.5 1/2, SCC2 -1.8 / -2.2 -1.6 / -2.0 -2.0 / -2.6 -87.8 1/2, LDREG -1.8 / -2.3 -2.0 / -2.5 1/2, LDIRR -1.8 / -2.5 -1.6 / -2.2 -2.1 / -2.7 24 16QAM 7.3 8.1 8.4 -78.7 6.7 7.6 7.4 -79.3 5.7 / 5.5 6.2 / 5.8 5.7 / 5.3 -80.3 7.0 / 6.4 7.3 / 6.6 6.8 / 6.0 -79.0 6.7 / 6.1 6.5 / 5.8 6.7 / 5.9 7.0 / 6.2 6.4 / 5.6 54 64QAM 3/4, CC6 16.0 17.2 -70.0 3/4, CC8 15.4 16.4 16.3 -70.6 3/4, PCC3 14.9 / 14.7 15.5 / 15.4 14.7 / 14.5 -71.1 3/4, SCC2 15.4 / 14.9 15.9 / 15.7 15.0 / 14.6 3/4, LDREG 15.4 / 15.1 15.8 / 15.5 15.0 / 14.7 3/4, LDIRR 15.3 / 14.9 15.7 / 15.5 14.9 / 14.4 -70.7 AWGN channel Abbreviations: max = maxlog decoding; jac = jacobian logarihm decoding Ravi Mahadevappa, Stephan ten Brink, Realtek

Rate Table (C2) 802.11a, 1x1, Different Codes 2/24/2019 doc.: IEEE 802.11-04/0014r1 January 2004 Rate Table (C2) 802.11a, 1x1, Different Codes Data rate (Mbps) Constellation Code rate, code MIMO mode Bandwidth (MHz) simulation result: Required Es/N0 (time: Es/N0fr-0.9dB) [dB] (10% PER, 1000bits), (1%, 1000), (10%, 10000) RX sensitivity [dBm] (10% PER, NF=10dB, margin 5dB) 20MHz: (-174+73+10+5)dBm+Es/N0 (10% PER, 1000bits) 6 BPSK 1/2, CC6 1x1 20 4.5 8.2 6.1 -81.5 1/2, CC8 3.6 7.1 4.4 -82.4 1/2, PCC3 7.3 3.0 1/2, SCC2 3.9 7.4 -82.1 1/2, LDREG 7.8 -81.6 24 16QAM 12.7 16.5 14.0 -73.3 12.2 15.9 12.8 -73.8 11.9 15.7 12.3 -74.1 12.4 15.5 12.5 -73.6 16.3 -73.2 54 64QAM 3/4, CC6 22.8 26.7 24.6 -63.2 3/4, CC8 21.9 26.1 -64.1 3/4, PCC3 22.0 26.0 21.1 -64.0 3/4, SCC2 22.1 27.1 22.4 -63.9 3/4, LDREG 26.6 22.2 Delay profile: Exp. decay Trms=60ns maxlog decoding used for all codes Ravi Mahadevappa, Stephan ten Brink, Realtek Realtek

Rate Table (C3) 802.11a, 2x3, AMRC, Diff. Codes January 2004 Rate Table (C3) 802.11a, 2x3, AMRC, Diff. Codes Data rate (Mbps) Constellation Code rate, code MIMO mode Bandwidth (MHz) simulation result: Required Es/N0 (time: Es/N0fr-0.9dB) [dB] (10% PER, 1000bits), (1%, 1000), (10%, 10000) RX sensitivity [dBm] (10% PER, NF=10dB, margin 5dB) 20MHz: (-174+73+10+5)dBm+Es/N0 (10% PER, 1000bits) 6 BPSK 1/2 CC6 2x3 AMRC 20 -4.6 -3.0 -3.6 -90.6 1/2 CC8 -5.1 -4.3 -91.1 1/2 PCC3 -5.7 -5.8 -91.7 1/2 SCC2 -3.5 -5.0 1/2 LDREG -4.8 -91.0 24 16QAM 3.7 5.3 5.0 -82.3 3.2 4.7 4.3 -82.8 2.5 3.8 2.7 -83.5 4.0 -82.0 3.5 4.8 3.6 -82.5 54 64QAM 3/4 CC6 12.6 14.3 13.8 -73.4 3/4 CC8 11.8 13.5 13.0 -74.2 3/4 PCC3 11.7 13.2 -74.3 3/4 SCC2 15.0 12.1 -72.8 3/4 LDREG 12.2 13.6 12.0 -73.8 Delay profile: Exp. decay Trms=60ns maxlog decoding used for all codes Ravi Mahadevappa, Stephan ten Brink, Realtek

Rate Table (C4) High-rate, 2x3, SMX, Diff. Codes January 2004 Rate Table (C4) High-rate, 2x3, SMX, Diff. Codes Data rate (Mbps) Constellation Code rate, code MIMO mode Bandwidth (MHz) simulation result: Required Es/N0 (time: Es/N0fr-0.9dB) [dB] (10% PER, 1000bits), (1%, 1000), (10%, 10000) RX sensitivity [dBm] (10% PER, NF=10dB, margin 5dB) 20MHz: (-174+73+10+5)dBm+Es/N0 (10% PER, 1000bits) 108 64QAM 3/4 CC6 2x3 SMX 20 19.5 21.9 20.5 -66.5 3/4 CC8 18.7 20.8 19.9 -67.3 3/4 PCC3 18.2 20.0 -67.8 3/4 LDREG 18.5 20.6 18.4 -67.5 126 7/8 CC6 23.3 25.9 25.6 -62.7 7/8 CC8 24.8 23.9 -64.1 7/8 PCC3 21.5 23.8 21.4 -64.5 7/8 LDREG 21.6 144 256QAM 24.2 26.9 25.7 -61.8 23.6 25.8 24.4 -62.4 23.1 25.0 23.4 -62.9 -62.6 168 28.4 31.7 31.1 -57.6 27.3 30.1 29.7 -58.7 26.8 29.1 26.7 -59.2 29.3 ZF MIMO SMX detection Delay profile: Exp. decay Trms=60ns maxlog decoding used for all codes Ravi Mahadevappa, Stephan ten Brink, Realtek