Key Features Summary and Results Update November 2004 Key Features Summary and Results Update Institute for Infocomm Research (I2R) Sumei SUN, WU Yan, LI Yuan, Patrick FUNG, Ying-Chang LIANG, Zhongding LEI (email to: sunsm@i2r.a-star.edu.sg) 16 November 2004 Institute for Infocomm Research (I2R)

Outline Summary of Key Features Results Update November 2004 Outline Summary of Key Features Results Update Performance comparison of CDD, SM and GSTBC Performance comparison of Unequal Error Protection (UEP) mapping and direct mapping in LDPC Institute for Infocomm Research (I2R)

November 2004 Summary of Key Points - 1 For 4x2 MIMO, the GSTBC open loop structure has the following advantages: Excellent performance – Up to 6 dB gain over 2x2 SM, and up to 5dB gain over 4x2 CDD; Simple implementation; No CSI. Institute for Infocomm Research (I2R)

November 2004 Summary of Key Points - 2 For 4x2 MIMO, Fixed beamforming has the following advantages: No requirement for instantaneous CSI, but only 2nd order channel statistics; No requirement for dedicated PPDU; Simple implementation – time domain beamforming reduced the per user complexity; Slower tracking requirement. Institute for Infocomm Research (I2R)

Summary of Key Points - 3 Long preamble design: November 2004 Summary of Key Points - 3 Long preamble design: Can be readily integrated into the training field; Reduced overhead – better efficiency; Enabling simple channel estimation; Enabling more accurate residual frequency offset estimation. Institute for Infocomm Research (I2R)

November 2004 Summary of Key Points - 4 Unequal Error Protection (UEP) mapping in LDPC Simple implementation; Performance gains at no additional cost. Institute for Infocomm Research (I2R)

Summary of Key Points - 5 2-D Linear transform Reduced PAPR; November 2004 Summary of Key Points - 5 2-D Linear transform Reduced PAPR; Further SNR gains; Can be seamlessly integrated with Spatial Spreading and CDD. Institute for Infocomm Research (I2R)

Performance comparison of CDD, SM and GSTBC November 2004 Results Update – Part 1 Performance comparison of CDD, SM and GSTBC Institute for Infocomm Research (I2R)

November 2004 PER Comparison of 2-rx MRC, CDD and STBC, Conv Code (chan B perfect CE and FOE ) -5 5 10 15 20 25 30 -4 -3 -2 -1 SNR per receive antenna (dB) PER 0.65dB 0.71dB 1.4dB 1 ´ 2 SIMO 2 2 CDD delay=32 2 STBC 108 Mbps 48 Mbps 24 Mbps Diversity order of 2-rx MRC Diversity order of STBC Diversity order of CDD STBC gives the lower bound of CDD! Institute for Infocomm Research (I2R)

November 2004 PER Comparison of 2x2 SM, 4x2 CDD and 4x2 GSTBC, Conv Code (chan B with practical CE and FOE ) 5 10 15 20 25 30 35 -3 -2 -1 SNR per receive antenna (dB) PER 0.98dB 2.1dB 4.8dB 2 ´ 24Mbps SM 48Mbps SM 108Mbps SM 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD 40MHz BW, ³ 1000B packet, Channel Model B Convolutional coded with CE, FOE and PC At PER=10-1, CDD does not have much of gain over SM; GSTBC outperforms CDD and SM, and the higher the modulation order, the more the gain. Institute for Infocomm Research (I2R)

November 2004 PER Comparison of 2x2 SM, 4x2 CDD and 4x2 GSTBC, LDPC (chan B with practical CE and FOE ) 5 10 15 20 25 30 35 -4 -3 -2 -1 40 MHz BW 4 ´ 2 two group CDD Channel B DC11 LDPC coded with CE FOE delay=32 SNR per receive antenna (dB) per 0.24dB 0.94dB 1.7dB 2 24Mbps SM 48Mbps SM 108Mbps SM 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD A more powerful code can better exploit the advantage of CDD. CDD outperforms SM, but still inferior to GSTBC. Institute for Infocomm Research (I2R)

November 2004 PER Comparison of 2x2 SM, 4x2 CDD and 4x2 GSTBC, LDPC (chan E with practical CE and FOE ) 5 10 15 20 25 30 -4 -3 -2 -1 40 MHz BW 4 ´ 2 two group CDD Channel E DC11 LDPC coded with CE FOE delay=32 SNR per receive antenna (dB) per 0.97dB 1.6dB 2.6dB 2 24Mbps SM 48Mbps SM 108Mbps SM 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD Even with a more powerful code, the diversity gain from CDD can not be very well exploited. Institute for Infocomm Research (I2R)

Diversity Order of 2x2 SM, 4x2 CDD, and 4x2 GSTBC, Linear Detection November 2004 Diversity Order of 2x2 SM, 4x2 CDD, and 4x2 GSTBC, Linear Detection Assume linear detection : i.e. no diversity gain from detection. SM: dsys  min(dpath, dfree); CDD : dsys  min(2×dpath, dfree); GSTBC: dsys  2×min(dpath, dfree); dSM  dCDD  dGSTBC Institute for Infocomm Research (I2R)

Performance Comparison of UEP and Direct Mapping in LDPC November 2004 Results Update – Part 2 Performance Comparison of UEP and Direct Mapping in LDPC Institute for Infocomm Research (I2R)

The Scheme Conventional scheme—direct mapping November 2004 The Scheme Conventional scheme—direct mapping Pre-designed UEP permutation embedded in LDPC encoder Systematic bits in LDPC require more protection than parity check bits Different from bit-interleaver: no latency, no additional complexity Write coded sequence (systematic + parity) into a rectangular block of put systematic bits into MSB positions. Institute for Infocomm Research (I2R)

Simulation Setup for LDPC Coded QAM with 2x2 SM November 2004 Simulation Setup for LDPC Coded QAM with 2x2 SM PD-LDPC (2304, 1152) of R=1/2; UEP vs Direct mapping H1 designed using progressive edge growth (PEG); Three kinds of H1 column weights: 4, 6, 8. 64QAM with Gray mapping; Single encoder for two spatial streams in 2x2 SM Practical Receiver FOE, PC, CE and SNR estimation Channel model B and E Institute for Infocomm Research (I2R)

2x2 SM in Channel B UEP vs Direct mapping Weight, w Gain,dB 4 0.28 6 November 2004 2x2 SM in Channel B UEP vs Direct mapping Weight, w Gain,dB 4 0.28 6 0.46 8 1.2 w=6 vs w=4 UEP: gain=0.18dB Direct: gain=0dB PD-LDPC of w=8 does not introduce performance gain at PER=10-2, although it shows higher diversity order. Institute for Infocomm Research (I2R)

2x2 SM in Channel E UEP vs Direct mapping Weight, w Gain,dB 4 0.29 6 November 2004 2x2 SM in Channel E UEP vs Direct mapping Weight, w Gain,dB 4 0.29 6 0.67 8 1.6 Gain from w=6 to w=4 UEP: gain=0.15dB Direct: gain=-0.25dB PD-LDPC of w=8 does not perform better than w=4 and 6 at PER=10-2. Institute for Infocomm Research (I2R)

UEP permutation is superior to direct mapping November 2004 Summary UEP permutation is superior to direct mapping Performance gain at target PER gain increases with column weight of PD-LDPC At best choice of w=6, gains are 0.46dB and 0.67dB for Channel Model B and E Performance gain achieved at no extra cost not extra redundancy; no extra latency (embedded in LDPC encoder); no extra encoder/decoder complexity (pre-designed). Institute for Infocomm Research (I2R)