Introduction of TGnSync 802.11n proposal

1. Introduction of TGnSync 802.11n proposal Speaker:Zih-Yin Ding Professor: Tzi-Dar Chiueh September 27th, 2004

2. Outline • Introduction of 802.11n • Motivation • Functional Requirement • PrimarySchedule Milestones • Introduction of the TGnSync 802.11n Proposal • PHY Enhancement Techniques • Operation Modes • Packet format • Conclusion • Reference

3. Motivation • High throughput drives the demand for 802.11n [3]

4. Project Authorization Request (PAR) • 802.11n PAR scope: • To define standardized modifications to both the 802.11 physical layers (PHY) and the 802.11 Medium Access Control Layer (MAC) so that modes of operation can be enabled that are capable of much higher throughputs, with a maximum throughput of at least 100Mbps, as measured at the MAC data service access point (SAP).

5. Functional Requirement

6. PrimarySchedule Milestones Issue First Letter Ballot on Draft 1.0 July 2005 Issue First Sponsor Ballot Mar 2006 Complete Sponsor ballot - accepted by ExCom Nov 2006 Publish Mar 2007

7. An Introduction of the Proposal of TGnSync

8. TGnSync • Some of TGnSync members include: Agere Systems Inc. Atheros Communications Inc. Cisco Systems, Inc. Intel Corporation Marvell Semiconductor, Inc. Nokia Corporation Nortel Networks Corporation Panasonic (Matsushita Electric Industrial Co. Ltd.) Royal Philips Electronics N.V. Samsung Electronics Co. Ltd. SANYO Electric Co. Ltd. Sony Corporation Toshiba Corporation

9. PHY Enhancement Techniques (1/2) • High Throughput Enhancement involved • Spatial Multiplexing using MIMO • Increasing the channel bandwidth • Reducing the guard interval overhead • Increasing the coding rate

10. PHY Enhancement Techniques (2/2) • Link Robustness Enhancement Techniques • Keep the client low cost and low power • Transmitter beamforming • Advanced transmitter beamforming techniques • Water-filling concept • Unequal power ratios and different choice of modulation-coding schemes on various spatial streams • Advanced channel coding • Low density parity code (LDPC) • CC+RS

11. PHY Features • MIMO evolution of 802.11 OFDM PHY – up to 4 spatial streams • 20 and 40MHz channels • 2x2 architecture – 140Mbps in 20MHz and 315Mbps in 40MHz • Preamble allows seamless interoperability with legacy 802.11a/g • Optional enhancements • Transmit beamforming with negligible overhead at the client • Advanced channel coding techniques (RS, LDPC) • 1/2 guard interval (i.e. 400ns) • 7/8 coding rate

12. MIMO Transmission Modes • Basic MIMO Mode (Mandatory) • Nss=NTX • Basic MIMO with TX Beamforming (optional) : BF-MIMO • Nss<= NTX • All spatial stream have identical MCS and power level • Advanced MIMO with TX Beamforming (optional): ABF-MIMO • Nss<= NTX • MCS and power level in each spatial stream can be different

13. TX Arch: Spatial Division Multiplexinge.g.2 Spatial streams with 2 TX antennas (mandatory) iFFT Modulator Preamble insert GI window symbols Pilots Frequency Interleaver Constellation Mapper Scrambled MPDU iFFT Modulator Preamble Channel Encoder Puncturer Spatial parser insert GI window symbols Pilots Frequency Interleaver Constellation Mapper

14. TX Arch: Spatial Division Multiplexinge.g.2 Spatial streams with 3 TX antennas (optional) HT LTF iFFT Mod. insert GI window Pilots Frequency Interleaver Constellation Mapper Spatial Steering (TX Beamforming), or Orthogonal Spatial Spreading with Cyclical Delay iFFT Mod. insert GI window HT LTF Scrambled MPDU Channel Encoder Puncturer Spatial Parser Pilots iFFT Mod. insert GI Frequency Interleaver Constellation Mapper window

15. Band Design for 20 and 40 MHz • 20 MHz: • Identical to 802.11a • 64 point FFT • 48 data tones • 4 pilot tones -26 -21 -7 -1 +1 +7 +21 +26 Tone Fill in the Guard Band • 40 MHz: • 128 point FFT • 108 data tones • 6 pilot tones -25 -11 +11 +25 +53 -53 +32 -2 +2 -64 -58 -32 -6 +6 +58 +63 Legacy 20 MHz in Lower Sub-Channel Legacy 20 MHz in Upper Sub-Channel

16. 2x2-40 MHz 4x4-20 MHz 2x3-20 MHz w/ short GI 2x2-20 MHz w/ short GI Motivation for 40MHz Channelization • 2x2 – 40 MHz • Only 2 RF chains => Cost effective & low power • Lower SNR at same throughput => Enhanced robustness 260 240 220 200 Sweet spot for 100Mbps top-of-MAC 180 160 140 Over the Air Throughput (Mbps) 120 100 80 Basic MIMO MCS set No impairments 1000 byte packets TGn channel model B 60 40 20 0 0 5 10 15 20 25 30 35 SNR (dB)

17. Basic MCS Set * Optional short GI (400ns) increases rates by 11.1%

18. Packet format

19. Packet format (2 spatial stream) L-STF L-LTF L-SIG HT-SIG HT-DATA HT LTF-2 ANT_1 HT STF HT LTF-1 20MHz Legacy Compatible Preamble HT-specific Preamble Legend L- Legacy HT- High Throughput STF Short Training Field LTF Long Training Field SIG Signal Field • The HT-SIG include Length, MCS, Advanced options and CRC(cyclic redundancy check)

20. HT Packet Detection L-STF L-LTF L-SIG HT-SIG • Auto-detection scheme on HT-SIG • Q-BPSK modulation • Invert the polarity of the pilot tones or Legacy DATA L-STF L-LTF L-SIG Legacy Compatible Preamble BPSK -1 +1 Q-BPSK +1 -1

21. HT Training Fields • HT-STF • 2nd AGC measurement is used to fine-tune MIMO reception • HT-LTF • Used for MIMO channel estimation • Additional frequency or time alignment • The number of HT-LTF= The number of spatial stream

22. Conclusion • The proposal proposed by TGnSync is introduced. • From this proposal, we can find some techniques that may be introduced in High Through WLAN are • MIMO technique, wider channel bandwidth, reduced guard interval, increased coding rate and advanced coding

23. Reference [1] TGnSync Website: http://www.tgnsync.org [2] TGnSync Present slide- DCN:11-04-0888-02-000n [3] http:// snrc.stanford.edu/events/industry- seminar/spring03/slides/taekon.pdf

24. Backup slides

25. 20/40 MHz Interoperability • 20 MHz PPDU into a 40 MHz receiver • The active 20 MHz sub-channel is detected using energy measurement of the two sub-channels • Inactive tones at the FFT output (i.e. 64 out of 128) are not used • 40 MHz PPDU into a20 MHz receiver • One 20 MHz sub-channel is sufficient to decode the L-SIG and the HT-SIG

26. Advanced technique • Beamforming • To increase the antenna gain in the direction of an intended receiver • One method to calculate V involves SVD of the channel transfer matrix H • Channel state information is needed • Reciprocity is assumed • RF calibration is needed

27. Mandatory v.s. optional • Mandatory: 20MHz, spatial multiplexing • Optional: Beamforming, 20MHz or 40MHz channel bandwidth, LDPC

28. Packet format in 20MHz HT STF HT LTF-1 HT LTF-2 L-STF L-LTF L-SIG HT-SIG HT-DATA ANT_1 20MHz L-STF L-LTF L-SIG HT-SIG HT-DATA ANT_2 20MHz Legacy Compatible Preamble HT-specific Preamble Legend L- Legacy HT- High Throughput STF Short Training Field LTF Long Training Field SIG Signal Field

29. Overview of key mandatory features • The WWiSE proposal’s mandatory modes are: • 2 transmit antennas • 20 MHz operation • 135 Mbps maximum PHY rate • 2x1 transmit diversity modes, 20 MHz • Mixed mode preambles enabling on-the-air legacy compatibility • Efficient greenfield preambles – no increase in length over legacy • Enhanced efficiency MAC mechanisms • All components based on enhancement of existing COFDM PHY

30. Overview of key optional features • The WWiSE proposal’s optional modes are: • 3 and 4 transmit antennas • 40 MHz operation • Up to 540 Mbps PHY rate • 2x1, 3x2, 4x2, 4x3 transmit diversity modes • Advanced coding: Rate-compatible LDPC code