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TGn Sync Complete Proposal

TGn Sync Complete Proposal. Date: September 14 th , 2004 Aon Mujtaba, Agere Systems Inc., ( mujtaba@agere.com ) Adrian P Stephens, Intel Corporation, ( adrian.p.stephens@intel.com ) Alek Purkovic, Nortel Networks ( apurkovi@nortelnetworks.com ) Andrew Myles, Cisco Systems ( amyles@cisco.com )

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TGn Sync Complete Proposal

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  1. TGn Sync Complete Proposal Date: September 14th, 2004 Aon Mujtaba, Agere Systems Inc., (mujtaba@agere.com) Adrian P Stephens, Intel Corporation, (adrian.p.stephens@intel.com) Alek Purkovic, Nortel Networks (apurkovi@nortelnetworks.com) Andrew Myles, Cisco Systems (amyles@cisco.com) Brian Johnson, Nortel Networks Corporation, (brjohnso@nortelnetworks.com) Chiu Ngo, Samsung Electronics Co. Ltd., (chiu.ngo@samsung.com) Daisuke Takeda, Toshiba Corporation, (daisuke.takeda@toshiba.co.jp) Darren McNamara, Toshiba Corporation, (Darren.McNamara@toshiba-trel.com) Dongjun (DJ) Lee, Samsung Electronics Co. Ltd., (djthekid.lee@samsung.com) David Bagby, Calypso Consulting, (david.bagby@ieee.org) Eldad Perahia, Cisco Systems, (eperahia@cisco.com) Huanchun Ye, Atheros Communications Inc., (hcye@atheros.com) Hui-Ling Lou, Marvell Semiconductor Inc., (hlou@marvell.com) James Chen, Marvell Semiconductor Inc., (jamesc@marvell.com) James Mike Wilson, Intel Corporation, (james.mike.wilson@intel.com) Jan Boer, Agere Systems Inc., (janboer@agere.com) Jari Jokela, Nokia, (jari.jokela@nokia.com) Jeff Gilbert, Atheros Communications Inc., (gilbertj@atheros.com) Job Oostveen, Royal Philips Electronics, (job.oostveen@philips.com) Syed Aon Mujtaba, Agere Systems, et. al.

  2. Authors (continued) Joe Pitarresi, Intel Corporation, (joe.pitarresi@intel.com) Jörg Habetha, Royal Philips Electronics, (joerg.habetha@philips.com) John Sadowsky, Intel Corporation, (john.sadowsky@intel.com) Jon Rosdahl, Samsung Electronics Co. Ltd., (jon.rosdahl@partner.samsung.com) Luke Qian, Cisco Systems, (lchia@cisco.com) Mary Cramer, Agere Systems (mecramer@agere.com) Masahiro Takagi, Toshiba Corporation, (masahiro3.takagi@toshiba.co.jp) Monisha Ghosh, Royal Philips Electronics, (monisha.ghosh@philips.com) Nico van Waes, Nokia, (nico.vanwaes@nokia.com) Osama Aboul-Magd, Nortel Networks Corporation, (osama@nortelnetworks.com) Paul Feinberg, Sony Electronics Inc., (paul.feinberg@am.sony.com) Pen Li , Royal Philips Electronics (pen.li@philips.com) Peter Loc, Marvell Semiconductor Inc., (ploc@marvell.com) Pieter-Paul Giesberts, Agere Systems Inc., (pgiesberts@agere.com) Richard van Leeuwen, Agere Systems Inc., (rleeuwen@agere.com) Ronald Rietman, Royal Philips Electronics, (ronald.rietman@philips.com) Seigo Nakao, SANYO Electric Co. Ltd., (snakao@gf.hm.rd.sanyo.co.jp) Sheung Li, Atheros Communications Inc., (sheung@atheros.com) Stephen Shellhammer, Intel, (stephen.j.shellhammer@intel.com) Taekon Kim, Samsung Electronics Co. Ltd., (taekon.kim@samsung.com) Takashi Fukagawa, Panasonic, (fukagawa.takashi@jp.panasonic.com) Takushi Kunihiro, Sony Corporation, (kuni@wcs.sony.co.jp) Teik-Kheong (TK) Tan, Royal Philips Electronics, (tktan@philips.com) Syed Aon Mujtaba, Agere Systems, et. al.

  3. Authors (continued) Tomoko Adachi, Toshiba Corporation, (tomo.adachi@toshiba.co.jp) Tomoya Yamaura, Sony Corporation, (yamaura@wcs.sony.co.jp) Tsuguhide Aoki, Toshiba Corporation, (tsuguhide.aoki@toshiba.co.jp) Victor Stolpman, Nokia, (victor.stolpman@nokia.com) Won-Joon Choi, Atheros Communications Inc., (wjchoi@atheros.com) Xiaowen Wang, Agere Systems Inc., (xiaowenw@agere.com) Yasuhiko Tanabe, Toshiba Corporation, (yasuhiko.tanabe@toshiba.co.jp) Yasuhiro Tanaka, SANYO Electric Co. Ltd., (y_tanaka@gf.hm.rd.sanyo.co.jp) Yoshiharu Doi, SANYO Electric Co. Ltd., (doi@gf.hm.rd.sanyo.co.jp) Youngsoo Kim, Samsung Electronics Co. Ltd., (KimYoungsoo@samsung.com) Yuichi Morioka, Sony Corporation, (morioka@wcs.sony.co.jp) Syed Aon Mujtaba, Agere Systems, et. al.

  4. TGn Sync Proposal Team - Background • Team operated as a technical group to help motivate a rapid introduction of the 802.11n standard • Participating companies from a broad range of markets • PC • Enterprise • Consumer Electronics • Semiconductor • Handset • Public Access • Solution incorporates a worldwide perspective of perceived market demand and regulatory concerns • Representation from North America, Europe and Asia Pacific regions Syed Aon Mujtaba, Agere Systems, et. al.

  5. Proposal Overview • High throughput and minimal design complexity • Superior robustness for a broad range of applications • Low cost • Low power • Scalable architecture • Seamless interoperability with 802.11 legacy devices • Offering global compliance and interoperability in all major regulatory domains (including licensed 10MHz modes) Syed Aon Mujtaba, Agere Systems, et. al.

  6. PHY Summary of TGn Sync Proposal • MIMO evolution of 802.11 OFDM PHY – up to 4 spatial streams • 20 and 40MHz* channels – fully interoperable • 2x2 architecture – 140Mbps in 20MHz and 315Mbps in 40MHz • Scalable up to 630Mbps • 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 rate coding *Not required in regulatory domains where prohibited. Syed Aon Mujtaba, Agere Systems, et. al.

  7. MAC Summary of TGn Sync Proposal • Supports 802.11e • Frame aggregation, single and multiple* destinations • Bi-directional data flow • Link adaptation with explicit feedback and control of channel sounding packets • Protection mechanisms for seamless interoperability and coexistence with legacy devices • Channel management (including management of 20/40MHz operating modes) • Power management for MIMO receivers * Optional Syed Aon Mujtaba, Agere Systems, et. al.

  8. PHY Syed Aon Mujtaba, Agere Systems, et. al.

  9. PHY Architectural Features • Throughput enhancement: • Spatial division multiplexing using MIMO-OFDM • Bandwidth expansion  interoperable 20MHz and 40MHz* • Increased channel coding rate (i.e. 7/8) • Shortened guard interval (i.e. 400ns) • Robustness enhancement: • Orthogonal spatial spreading with cyclic delay • Transmit beamforming • Advanced coding Max rate in 20MHz = 140Mbps Max rate in 40MHz = 315Mbps (with 2x2 architecture using 2 spatial streams) Reduces SNR requirement by more than 10dB * Not required in regulatory domains where prohibited Syed Aon Mujtaba, Agere Systems, et. al.

  10. Mapping Spatial Streams to Multiple Antennas • Number of spatial streams = Number of TX antennas • 1 spatial stream mapped to 1 antenna • Spatial division multiplexing • Equal rates on all spatial streams • Number of spatial streams ≤ Number of TX antennas • Each spatial stream mapped to all transmit antennas • Optional orthogonal spatial spreading • Exploits all transmit antennas • No channel state info at TX required • Optional transmit beamforming • Focusing the energy in a desired direction • Requires channel state info at TX • Supports unequal rates on different spatial streams • With per spatial stream training, no change needed at the RX Syed Aon Mujtaba, Agere Systems, et. al.

  11. 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 Syed Aon Mujtaba, Agere Systems, et. al.

  12. Tone 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 Syed Aon Mujtaba, Agere Systems, et. al.

  13. 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) Syed Aon Mujtaba, Agere Systems, et. al.

  14. Basic MCS Set ‡ Duplicate format, BPSK R = ½ provides 6 Mbps for 40 MHz channels * Optional short GI (400ns) increases rates by 11.1% Syed Aon Mujtaba, Agere Systems, et. al.

  15. HT-PPDU 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 Legacy Compatible Can be decoded by anylegacy 802.11a or g compliant device for interoperability Syed Aon Mujtaba, Agere Systems, et. al.

  16. L-STF L-LTF L-SIG HT-SIG HT-DATA Duplicate L-STF Duplicate L-LTF Dup. L-SIG Duplicate HT-SIG HT-PPDU Format in 40MHz ANT_1 40MHz HT STF HT LTF-1 HT LTF-2 L-STF L-LTF L-SIG HT-SIG HT-DATA ANT_2 40MHz Duplicate L-STF Duplicate L-LTF Dup. L-SIG Duplicate HT-SIG Legacy Compatible Preamble HT-specific Preamble Syed Aon Mujtaba, Agere Systems, et. al.

  17. Spoofing • Spoofing is the use of the legacy RATE and LENGTH fields to keep the legacy STA off the air for a desired period of time • The duration indicated in the L-SIG can exceed the actual duration in the HT-SIG  MAC uses this as a protection mechanism • For a HT-PPDU, L-SIG RATE is hard-coded at 6 Mbps • max MSDU length = 2304 Bytes spoofing duration up to ~3 msec Syed Aon Mujtaba, Agere Systems, et. al.

  18. HT PPDU Detection L-STF L-LTF L-SIG HT-SIG • Auto-detection scheme on HT-SIG • Q-BPSK modulation (BPSK w/ 90-deg rotation) • Invert the polarity of the pilot tones • Combined methods provide speed and reliability • L-SIG reserved bit is not used • Legacy devices are using the “reserved bit” in undefined ways or Legacy DATA L-STF L-LTF L-SIG Legacy Compatible Preamble Syed Aon Mujtaba, Agere Systems, et. al.

  19. MCS (6 bits) MCS (6 bits) HTLENGTH (18 bits) HTLENGTH (18 bits) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 HTSIG1 HTSIG1 SOUNDING PACKET (1 bit) ADV CODING (2 bits) NUMBER HT-LTF (2 bits) 20/40 BW (1 bit) SCRAMBLER INIT (2 bits) SHORT GI (1 bit) AGGRAGATE (1 bit) CRC (8 bits) SIGNAL TAIL (6 bits) SIGNAL TAIL (6 bits) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 HTSIG2 HTSIG2 Transmit Order Transmit Order HT-SIG Contents Syed Aon Mujtaba, Agere Systems, et. al.

  20. For MIMO, accurate AGC requires power estimates from each TX antenna to each RX antenna If L-STF is used for MIMO AGC, require orthogonalization of L-STF across multiple TX antennas Perfect orthogonality is achieved with tone interleaving However, tone interleaving is incompatible with legacy receivers using cross correlation on the L-STF Cyclic delay may be used to separate transmission paths, but the delay has to be limited to preserve the cross correlation property of the L-STF However, limited cyclic delay results in AGC inaccuracy, as shown on the next slide MIMO AGC multiple spatial streams single spatial stream L-STF L-LTF L-SIG HT-SIG HT-DATA AGC measured AGC locked Syed Aon Mujtaba, Agere Systems, et. al.

  21. Power Fluctuation with Cyclic Delay on the L-STF Data power 1 Power fluctuation with tone interleaving is within 1dB of the data power 0.9 STF = Tone Interleaved STF = Cyclic Delay 0.8 2x2, TGn Channel D SNR = 30dB 0.7 0.6 CDF(x) 0.5 Introduce a dedicated STF for MIMO that is tone interleaved Reduces 1 bit in the ADC  cost & power savings 0.4 0.3 0.2 0.1 0 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 x = Power fluctuation of AGC setting w.r.t. data power (dB) Syed Aon Mujtaba, Agere Systems, et. al.

  22. Power Fluctuation of HT-LTF w.r.t. Data Data power 1 0.9 HT-LTF = Tone Interleaved 0.8 HT-LTF = Walsh + Cyclic Delay Large deviation of HT-LTF power wrt data power will result in higher channel estimation error 0.7 2x2, TGn Channel D SNR = 30dB 0.6 CDF(x) 0.5 0.4 0.3 0.2 HT-LTF should be tone interleaved 0.1 0 -10 -8 -6 -4 -2 0 2 4 x = Power fluctuation of HT-LTF w.r.t. data (dB) Syed Aon Mujtaba, Agere Systems, et. al.

  23. Tone Interleaved 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 Syed Aon Mujtaba, Agere Systems, et. al.

  24. Spatial Stream Tone Interleaving • Color indicates spatial stream • Each HT-LTF has equal representation from all spatial streams • Eliminates avg. power fluctuation across LTFs • HT-LTS symbols are designed to minimize PAPR • Distinct symbol designs for different number of spatial streams Syed Aon Mujtaba, Agere Systems, et. al.

  25. Summary of HT-LTF • Robust design • Tone interleaving reduces power fluctuation • 2 symbols per field • 3dB of channel estimation gain with baseline per-tone estimation • Enables additional frequency offset estimation • Per spatial stream training • HT-LTF and HT-Data undergo same spatial transformation • Number of HT-LTFs = Number of spatial streams Syed Aon Mujtaba, Agere Systems, et. al.

  26. 20/40 MHz BSS Operation • A 20/40 MHz BSS supports interoperability among any combination of: • 20/40 MHz HT clients • 20 MHz HT client • 20 MHz legacy client • Not required in regulatory domains where prohibited Syed Aon Mujtaba, Agere Systems, et. al.

  27. 20/40 MHz Interoperability • 40 MHz PPDU into a 40 MHz receiver • Get 3dB processing gain – duplicate format allows combining the legacy compatible preamble and the HT-SIG in an MRC fashion • 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 • See MAC slides for additional information on 20/40 inter-op Syed Aon Mujtaba, Agere Systems, et. al.

  28. TX Arch: Basic TX Beamforming or Spatial Spreadinge.g.2 Spatial Streams with 3 TX Antennas (optional) Per Spatial Stream Processing: HT-LTF & HT-Data undergo same spatial transformation 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 Syed Aon Mujtaba, Agere Systems, et. al.

  29. SNR Gain with TX Beamforming 1000 byte packets No impairment 20MHz, channel D 4 TX-antenna AP  2 RX-antenna client ~10 dB gain of 4x2-ABF over 2x2-SDM => cost effective client Syed Aon Mujtaba, Agere Systems, et. al.

  30. Optional Advanced Coding Modes • Low Density Parity Check (LDPC) • Superior performance, especially at high code rates (7/8) • Reed-Solomon (RS) • Outer code concatenated with inner convolutional code • Very low cost, mature technology Syed Aon Mujtaba, Agere Systems, et. al.

  31. LDPC yields a 2x2 20 MHz high throughput solution at reasonable SNR! Syed Aon Mujtaba, Agere Systems, et. al.

  32. MAC Syed Aon Mujtaba, Agere Systems, et. al.

  33. MAC Challenges in HT Environment • HT requires an improvement in MAC Efficiency • HT requires effective Rate Adaptation • HT requires Legacy Protection Syed Aon Mujtaba, Agere Systems, et. al.

  34. New MAC Features • Aggregation Structure • Aggregation Exchanges • Protocol for link adaptation • Protocol for reverse direction data • Single and multiple responder • Protection Mechanisms • Coexistence & Channel Management • Header Compression • MIMO Power Management Syed Aon Mujtaba, Agere Systems, et. al.

  35. MAC Header Compression • MHDR MPDU carries repeated Header fields • CHDATA MPDU refers to previous MHDR MPDU • HID field ties the two together • Context only within current aggregate Syed Aon Mujtaba, Agere Systems, et. al.

  36. Robust Structure Aggregation is a purely-MAC function PHY has no knowledge of MPDU boundaries Simplest MAC-PHY interface Control and data MPDUs can be aggregated Aggregation Structure Syed Aon Mujtaba, Agere Systems, et. al.

  37. Aggregate Exchange Sequences • Aggregate exchange sequences include single frames or groups of frames that are exchanged “at the same time” • Allows effective use of Aggregate Feature • Allows control and data to be sent in the same PPDU • An initiator sends a PPDU and a responder may transmit a response PPDU • Either PPDU can be an aggregate (“Initiator” / “responder” are new terms relating to roles in aggregate exchange protocol) Syed Aon Mujtaba, Agere Systems, et. al.

  38. Basic Aggregate Exchange Syed Aon Mujtaba, Agere Systems, et. al.

  39. Reverse Direction Data Flow • Gives an opportunity for a responder to transmit data to an initiator during the initiator’s TXOP • Aggregates data with response control MPDUs • Reduces Contention • Effective in increasing TCP/IP performance Syed Aon Mujtaba, Agere Systems, et. al.

  40. Reverse Direction Protocol Syed Aon Mujtaba, Agere Systems, et. al.

  41. Link Adaptation Protocol • Support for PHY closed-loop modes with on-the-air signalling • Request for training and feedback are carried in control frames • Rate feedback supported • Transmit beamforming training supported • sounding packet • calibration exchange • Timing of response is not constrained permitting a wide range of implementation options Syed Aon Mujtaba, Agere Systems, et. al.

  42. Link Adaptation Protocol Syed Aon Mujtaba, Agere Systems, et. al.

  43. Multiple Receiver Aggregation • Aggregates can contain MPDUs addressed for multiple receiver addresses (MRA) • MRA may be followed by multiple responses from the multiple receivers • MRA is effective in improving throughput in applications where frames are buffered to many receiver addresses Syed Aon Mujtaba, Agere Systems, et. al.

  44. Periodic Multi-Receiver Aggregation Syed Aon Mujtaba, Agere Systems, et. al.

  45. MRA contains multiple IAC for One per response At most one per receiver IAC specifies response offset and duration Multiple Responses Syed Aon Mujtaba, Agere Systems, et. al.

  46. Protection Mechanisms • LongNAV • An entire sequence is protected by NAV set using MPDU duration field or during contention-free period • CF-end packet at end of EDCA TXOP sequence may be used to return unused time by resetting NAV • Pairwise Spoofing • Protection of pairs of PPDUs sent between an initiator and a single responder • Uses Legacy PLCP header duration spoofing • Single-ended Spoofing • Protection of aggregate and any responses using legacy PLCP spoofing at the initiator only • Can be used to protect multiple responses Syed Aon Mujtaba, Agere Systems, et. al.

  47. LongNAV protection • Provides protection of a sequence of multiple PPDUs • Provides a solution for .11b • Comes “for free” with polled TXOP • Gives maximum freedom in use of TXOP by initiator Syed Aon Mujtaba, Agere Systems, et. al.

  48. Protects pairs of PPDUs (current and following) Very low overhead, suitable for short exchanges, relies on robust PHY signaling Places Legacy devices into receiving mode for spoofed duration Spoofing is interpreted by HT devices as a NAV setting Pairwise Spoofing Protection Syed Aon Mujtaba, Agere Systems, et. al.

  49. Protects MRA and all responses Very low overhead, suitable for short exchanges Places legacy devices into receiving mode for spoofed duration Same level of protection as initiator CTS-to-Self Assuming CTS is sent at the lowest rate Single-Ended Spoofing Protection Syed Aon Mujtaba, Agere Systems, et. al.

  50. Following Packet Descriptor (FPD) Protocol Syed Aon Mujtaba, Agere Systems, et. al.

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