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

2 Outline Introduction of nIntroduction of n –Motivation –Functional Requirement –Primary Schedule Milestones Introduction of the TGnSync n ProposalIntroduction of the TGnSync n Proposal –PHY Enhancement Techniques –Operation Modes –Packet format ConclusionConclusion ReferenceReference

3 Motivation High throughput drives the demand for n [3]

4 Project Authorization Request (PAR) n PAR scope: –To define standardized modifications to both the physical layers (PHY) and the 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 FR1: Link throughput of 100Mbps at the top of the MAC SAP FR2: 20MHz channel (per device) FR3: Supports 5GHz bands FR4, 5: a &.11g backwards compatibility FR6: AP controls the support for legacy STA FR7: Supports.11e QOS FR8: Spectral efficiency of at least 3 bps/Hz for the PSDU FR9: Compliance to PAR

6 Primary Schedule 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

NTU Confidential 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 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 a/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) –N ss =N TX Basic MIMO with TX Beamforming (optional) : BF-MIMO –N ss <= N TX –All spatial stream have identical MCS and power level Advanced MIMO with TX Beamforming (optional): ABF-MIMO –N ss <= N TX –MCS and power level in each spatial stream can be different

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

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

15 Band Design for 20 and 40 MHz Legacy 20 MHz in Lower Sub-Channel Legacy 20 MHz in Upper Sub-Channel MHz: Identical to a 64 point FFT 48 data tones 4 pilot tones 40 MHz: 128 point FFT 108 data tones 6 pilot tones Tone Fill in the Guard Band

16 Motivation for 40MHz Channelization SNR (dB) Over the Air Throughput (Mbps) 2x2-40 MHz 4x4-20 MHz 2x2-20 MHz w/ short GI 2x3-20 MHz w/ short GI 2x2 – 40 MHz Only 2 RF chains => Cost effective & low power Lower SNR at same throughput => Enhanced robustness Basic MIMO MCS set No impairments 1000 byte packets TGn channel model B Sweet spot for 100 Mbps top-of-MAC

17 Basic MCS Set ModulationCode Rate Data Rates* 20 MHz (Mbps) (1,2,3,4 spatial streams) Data Rates* 40 MHz (Mbps) (1,2,3,4 spatial streams) BPSK1/26, 12, 18, , 27, 45.5, 54 QPSK1/212, 24, 36, 4827, 54, 81, 108 QPSK3/418, 35, 54, , 81, 121.5, QAM1/224, 48, 72, 9654, 108, 162, QAM3/436, 72, 108, 14481, 162, 243, QAM2/348, 96, 144, , 216, 324, QAM3/454, 108, 162, , 243, 364.5, QAM7/863, 126, 189, , 283.5, 425.2, QAM7/8 with ½ GI*70, 140, 210, , 315, 472.5, 630 * Optional short GI (400ns) increases rates by 11.1%

NTU Confidential 18 Packet format

19 Packet format (2 spatial stream) 20MHz ANT_1 Legend L-Legacy HT-High Throughput STFShort Training Field LTFLong Training Field SIGSignal Field L-STFL-LTFL-SIGHT-SIGHT-DATA Legacy Compatible PreambleHT-specific Preamble HT STF HT LTF-1 HT LTF-2 The HT-SIG include Length, MCS, Advanced options and CRC(cyclic redundancy check)

20 HT Packet Detection Auto-detection scheme on HT-SIG –Q-BPSK modulation –Invert the polarity of the pilot tones L-STFL-LTFL-SIGHT-SIG L-STFL-LTFL-SIG or Legacy DATA Legacy Compatible Preamble +1 BPSK Q-BPSK

21 HT Training Fields HT-STF –2 nd 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: [2] TGnSync Present slide- DCN: n [3] snrc.stanford.edu/events/industry- seminar/spring03/slides/taekon.pdf

NTU Confidential 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 a 20 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 20MHz ANT_1 Legend L-Legacy HT-High Throughput STFShort Training Field LTFLong Training Field SIGSignal Field L-STFL-LTFL-SIGHT-SIGHT-DATA L-STFL-LTFL-SIGHT-SIGHT-DATA Legacy Compatible PreambleHT-specific Preamble HT STF HT LTF-1 HT LTF-2 20MHz ANT_2

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