Institute for Infocomm Research (I2R) Results Updates 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

Outline CDD versus SM and GSTBC Unequal Error Protection (UEP) in LDPC November 2004 Outline CDD versus SM and GSTBC Unequal Error Protection (UEP) in LDPC Long Preamble Design Beamforming and FEC Institute for Infocomm Research (I2R)

Outline CDD versus SM and GSTBC Unequal Error Protection (UEP) in LDPC November 2004 Outline CDD versus SM and GSTBC Unequal Error Protection (UEP) in LDPC Long Preamble Design Beamforming and FEC 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 perfect CE and FOE ) 5 10 15 20 25 30 35 40 45 -3 -2 -1 coded PER SNR per receive antenna 1.6dB 2.5dB 5.1dB 2 ´ 24Mbps SM 48Mbps SM 108Mbps SM 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD CDD outperforms SM, but gap becomes smaller for higher order modulation; GSTBC outperforms CDD; and gain becomes higher for higher order modulation. Institute for Infocomm Research (I2R)

November 2004 PER Comparison of 2x2 SM, 4x2 CDD and 4x2 GSTBC, Conv Code (chan E perfect CE and FOE ) 5 10 15 20 25 30 35 40 45 -3 -2 -1 40MHz BW, ³ 1000B packet, Channel Model E coded PER SNR per receive antenna 2.4dB 3.2dB 6dB 2 ´ 24Mbps SM 48Mbps SM 108Mbps SM 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD CDD has same performance as SM at target PER; GSTBC outperforms CDD; the higher the modulation, the more the performance gains. Institute for Infocomm Research (I2R)

Effect of CE and FOE on 4x2 CDD, Conv Code (chan B ) November 2004 Effect of CE and FOE on 4x2 CDD, Conv Code (chan B ) 5 10 15 20 25 30 35 -3 -2 -1 Coded PER of 4 ´ 2 CDD with CE, FOE and PC SNR per receive antenna (dB) PER 2.1dB 1.4dB 0.95dB With CE, FOE and PC Perfect CE and Syn 2 108 Mbps 48 Mbps 24 Mbps Recall that performance degradation for GSTBC is 2.54, 1.82, and 1.67 dB, respectively for the three setup. 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 VBLAST 48Mbps VBLAST 108Mbps VBLAST 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 GSTBC still shows much better performance than CDD and SM. Institute for Infocomm Research (I2R)

November 2004 PER Comparison of 2x2 SM, 4x2 CDD and 4x2 GSTBC, LDPC (chan B with perfect 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 perfect CE FOE delay=32 SNR per receive antenna (dB) PER 0.99dB 1.1dB 2.6dB 2 24Mbps VBLAST 48Mbps VBLAST 108Mbps VBLAST 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD A more powerful code can better exploit the advantage of CDD. 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 VBLAST 48Mbps VBLAST 108Mbps VBLAST 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD CDD is less sensitive to channel estimation and synchronization errors than 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 VBLAST 48Mbps VBLAST 108Mbps VBLAST 24Mbps GSTBC 48Mbps GSTBC 108Mbps GSTBC 24Mbps CDD 48Mbps CDD 108Mbps CDD 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)

Further Work CDD + SS; CDD + SS + frequency domain transform. November 2004 Further Work CDD + SS; CDD + SS + frequency domain transform. Institute for Infocomm Research (I2R)

Outline CDD versus SM versus GSTBC November 2004 Outline CDD versus SM versus GSTBC Unequal Error Protection (UEP) in LDPC Long Preamble Design Beamforming and FEC 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 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 0.76dB 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)

Outline CDD versus SM versus GSTBC November 2004 Outline CDD versus SM versus GSTBC Unequal Error Protection (UEP) in LDPC Long Preamble Design Beamforming and FEC Institute for Infocomm Research (I2R)

Integration of Long Preamble (1/3) November 2004 Integration of Long Preamble (1/3) Ready integration of I2R long preamble design into HT-LTF structure to achieve overhead savings; improved residual frequency estimate in all modes Identical channel estimation performance + more accurate residual freq offset estimate GI s a v i n g 0.8s 13.6s One single GI per transmit antenna Institute for Infocomm Research (I2R)

Integration of Long Preamble (2/3) November 2004 Integration of Long Preamble (2/3) More reduction with more transmit antennas GI s a v i n g 2.4s Identical channel estimation performance + more accurate residual freq offset estimate 26.4s Institute for Infocomm Research (I2R)

Integration of Long Preamble (3/3) November 2004 Integration of Long Preamble (3/3) 13.6s HT-DATA GI 13.6s Institute for Infocomm Research (I2R)

Outline CDD versus SM versus GSTBC November 2004 Outline CDD versus SM versus GSTBC Unequal Error Protection (UEP) in LDPC Long Preamble Design Beamforming and FEC Institute for Infocomm Research (I2R)

A Simpler Beamforming Scheme November 2004 A Simpler Beamforming Scheme Common Beamforming I2R Scheme Instantaneous Dedicated PPDU Frequency domain (per tone) Fast (dependant on the channel fading frequency) CSI CSI estimation Beamforming Update frequency Channel covariance matrix (2nd order statistics) No PPDU (beamforming is transparent to the RX which needn’t know if the TX is in beamforming mode) Time domain (per user w/ much less complexity) Slow (subject to position or DOA change frequency) Institute for Infocomm Research (I2R)

November 2004 Further Studies For adaptive modulation and coding in SVD beamforming, we propose to compare the following: use separate encoders for different MIMO streams; use a single encoder, but transmit different codeword for different spatial streams; use a single encoder and single codeword for all the spatial streams, but optimize the puncturing pattern and bit assignment to different spatial streams. Institute for Infocomm Research (I2R)