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Project: 802.11n TG High Throughput WLAN

Project: 802.11n TG High Throughput WLAN. Submission Title: [11-04-1400-00-000n Comparison of proposals from TGn Sync and WWiSE with suggested evaluation additions ] Date Submitted: [November, 2004] Source: [John Egan, Rodger Tseng, Albert Liu ] Company [Infineon Technologies]

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Project: 802.11n TG High Throughput WLAN

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  1. Project: 802.11n TG High Throughput WLAN Submission Title: [11-04-1400-00-000n Comparison of proposals from TGn Sync and WWiSE with suggested evaluation additions] Date Submitted: [November, 2004] Source: [John Egan, Rodger Tseng, Albert Liu] Company [Infineon Technologies] Address: [ ] Voice:[ Egan: 727.789.8857, Tseng & Liu: +886-3-5788879] E-Mail:[ Egan.external@infineon.com, rodger.tseng@infineon.com, albert.liu@infineon.com ] Re : [] Abstract:[This document proposes potential changes to what usage and applications should be considered for proposal analysis (effects document “11-03-0802-12-000n-usage-models” IEEE 802.11-03/802r12) and a brief analysis of differences between the proposals from TGn Sync and WWiSE] Purpose:[To improve the TG’s ability to determine the best route forward while also keeping market/end user requirements in mind as part of the analysis] Notice:[This document has been prepared to assist the IEEE P802.11n. It is offered as a basis for discussion and is not binding on the contributing or supporting individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Based on changes the list of supporters may increase or decrease.] Release: [The contributors acknowledge and accept that this contribution becomes the property of IEEE and may be made publicly available by P802.11.] John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  2. Supporters John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  3. Overview • There should be more Use and Application cases. Here, we suggest three areas for inclusion. Eventual analysis of proposals must include verification against agreed upon scenarios. • The TGn Sync and WWiSE proposals were analyzed by Infineon. The other proposals were not analyzed due to resource and time constraints, not due to an Infineon view that they do not have merit consideration. John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  4. Topics • Usage Additions based on Applications (Speaker : John Egan) • TGn Sync & WWiSE Comparisons on PHY (Speaker : Rodger Tseng) • TGn Sync & WWiSE Comparisons on MAC (Speaker : Albert Liu) • Summary (Speaker : John Egan) John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  5. Use and Applications Additions Speaker: John Egan John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  6. Use and Applications Additions • PDA • Low power receiver and transmitter • Operating at edge of service area • Requires sleep mode for 802.11n module • Mobile while in session • Must not lose session • Streaming or random packets • Unidirectional for most streaming • Bidirectional for random John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  7. Use and Applications Additions • Wireless PAD • Envisioned to be mobile screen pad, next generation of Tablet PCs of today • Battery powered so must have power conservation mode • Mobile while in sessions • Video conference and streaming video required so must be bidirectional and requires error correction based on session type John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  8. Session Mobility • Has this been covered in simulations? • Is this similar to “Measuring the Impact of Slow User Motion on Packet Loss and Delay over IEEE 802.11b Wireless Links” submitted to 802.11b by Christian Hoene, André Günther, Adam Wolisz of the Technical University of Berlin? • Must include this in comparison simulations John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  9. TGn Sync & WWiSE Comparisons on PHY Speaker: Rodger Tseng John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  10. Throughput enhancement (M) Mandatory (O) Optional (N) Not available John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  11. Throughput comparison(Maximum achievable uncoded data rate @ 64QAM) (M) Mandatory (O) Optional Observations: (1). T > W, between “R=7/8 with ½ GI” for T and “R=5/6” for W. (2). W >= T, at “ R=3/4 & 2Tx” John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  12. Performance improvement (M) Mandatory (O) Optional (N) Not available John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  13. Observations & conclusionsbefore further detailed analysis John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  14. Suggestions & comments • Further extensive simulations are needed to identify • performance under identical conditions to enable • fair comparisons. • As both proposals employ mandatory and basic • MIMO-OFDM-SDM architecture in constructing • their modems, there exist possibility for harmonization • and convergence in the future. John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  15. TGn Sync & WWiSE Comparisons on MAC Speaker: Albert Liu John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  16. Feature comparisons John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  17. Feature comparisons (Con’t) John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  18. What is aggregation ? Legacy Burst PSDU2 PSDU3 PSDU1 MPDU Payload MPDU Payload MPDU Payload MPDU Header Preamble PLCP header Preamble PLCP header MPDU Header Preamble PLCP header MPDU Header FCS FCS FCS SIFS SIFS Perform aggregation Preamble + PLCP Header A-PSDU Preamble + PLCP headers + SIFS will be saved Some overheads will be induced to identify each MP(S)DU John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  19. TGn Sync Aggregation Pad to 4 bytes MPDU2 MPDU3 MPDU1 Preamble + PLCP Header A-PSDU Max PSDU Length = 264143B RSV/LEN/CRC/UP One mechanism can find next correct MPDU delimiter when the current one is broken 4B MPDU Delimiter + PAD induce 4B ~ 7B per MPDU John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  20. TGn Sync Header Compression Suggestion: No need HID 26B FC/DRU/a1/a2/a3/SC/QC Uncompressed header MPDU3 MPDU2 MPDU1 Perform header compression CHDATA header FC/SC/HID/RSV MHDR MPDU 30B FC/DRU/a1/a2/a3/HID/RSV/QoS/FCS 6B CHDATA header can save 26B-6B = 20B per MPDU John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  21. CHDATA Payload CHDATA Header CHDATA Payload CHDATA Payload CHDATA Header CHDATA Header TGn Sync Aggregation + Header Compression MHDR MPDU CHDATA MPDU1 CHDATA MPDU2 CHDATA MPDU3 MHDR MPDU A-PSDU Induced 4~7B Saved 20B Saved - induced = 13B~16B per MPDU are saved John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  22. Suggestion1: enlarge A-MSDU Suggestion2 : SF-header needs CRC if suggestion 1 is applied MSDU headers 26B are saved A-MSDU Header MSDU3 payload MSDU2 payload MSDU1 payload SF-Header SF-Header SF-Header (8K) A-MSDU LEN/SA/DA Preamble + PLCP header 14B A-PSDU A-PSDU ZIFS+PLCP header  NOTE: PLCP header can NOT be efficiently saved SF-Header can save 26B-14B = 12B per MSDU WWiSE Aggregation John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  23. Aggregation Comparison Table John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  24. Case Study – TGn Sync • case 1 : Assume 24 MPDU (2KB), 1TX, 64QAM, 3/4 , --> 54Mbps , • No aggregated consumes : 24 preambles + 24 PLCP headers + 24 MPDU headers + 24 MPDUs + 23 SIFSs = 8006 us • Aggregated + header compression are applied: aggregated consumes : 1 preambles + 1 PLCP headers + 24 MPDU delimiters + 1 MPDU header + 1 HID + 24 compressed headers+ 24 MPDUs + {23 PAD octets} + IAC (40B) • 1) 23 preambles are saved = 23 * 16us = 368us are saved. • 2) 23 PLCP header are saved, 23*4us = 92us are saved. • 3) 23 SIFSs are saved = 23 * 10us = 230 us are saved. • 4) 23 MPDU header are saved = 23 * 26 = 598 bytes are saved • 5)extra (1 HID) and ( 24 compressed headers) and (24 * MPDU Delimiters) and (23 PAD octets) + IAC are consumed = 1 + ( 6 * 24) + ( 4 * 24) + ( 3 * 23) +40 = 350 byte are wasted • analysis 4) and 5) : ((598 - 350)*8)/216 = 10 symbols = 40 us are saved • conclusion : 368 + 92 + 230 + 40 = 730 us are saved • Performance improved : 730us / 8006us = 9.12% John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  25. Case Study – WWiSE • case 1 : Assume 24 MSDU (2KB) = 6 * A-MSDU, 1TX, 64QAM, 3/4 , --> 54Mbps , • No aggregated consumes : 24 preambles + 24 PLCP headers + 24 MSDU headers + 24 MSDUs + 23 SIFSs = 8006us • Aggregated is applied : aggregated consumes : 1 preambles + 6 PLCP headers + 6 MSDU headers + 24 sub-frame headers + 24 MSDUs • 1) 23 preamble are saved if all are ZIFS = 23 * 16us = 368us are saved • 2) 18 PLCP headers are saved = 18 * 4us = 72us are saved • 3) 23 SIFSs are saved = 23 * 10us = 230us are saved. • 4) 18 MSDU headers are saved. • 5) extra 24 sub -frame headers. • Analysis (worst case): One A-MSDU = ((14B*4- 26B*3 ) *8 )/216 = 0 symbols, total 6A-MSDU = 0 symbols = - 0us are saved • conclusions : 368 + 72 + 230 + 0 = 670 us are saved • Performance improved = 670/8006 = 8.37% John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  26. Comparison table for Case Study Item 4 and 5 need to be balanced John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  27. Performance Comparison 1) TGn Sync performance is better than WWiSE when aggregation + header compression is performed. • I.e. (case1) 24* 2KB packet => TGn Sync/WWiSE = 1.090 • I.e. (case 2)100*2KB packet => TGn Sync/WWiSE = 1.098 • I.e. (case 6) 24* 1KB packet => TGn Sync/WWiSE = 1.070 2) TGn Sync performance is worse than WWiSE when only aggregation is performed. • I.e. (case1) 24* 2KB packet => TGn Sync/WWiSE = 0.982 • i.e. (case2) 100*2KB packet => TGn Sync/WWiSE = 0.994 • I.e. (case6) 24* 1KB packet => TGn Sync/WWiSE = 0.965 John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  28. Conclusion • When there are more aggregated packets, regardless of size • When higher air speed (more bits inside one symbol) • The dominant factor will be the number of PLCP headers. Improvements to Aggregation need to be in the final 802.11n definition to achieve best performance page15 John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  29. Suggestions to these 2 campaigns (1) To TGn Sync: • Topic : Remove HID in MHDR MPDU and CHDATA MPDU. • Reason: For implementation feasibility, one MHDR MPDU should be often followed by same a1/a2/a3’s CHDATA MPDU. • Benefit: save one byte HID may possibly save 4 bytes of padding in each MPDU. • Drawback: continuous MHDR MPDU with different HID are forbidden. (2) To WWiSE: • Topic1 :Enlarge A-MSDU size to 256KB. • Reason: save more PLCP headers in A-PSDU • Benefit : save more PLCP headers mean more air time is saved. • Drawback: different address set (a1/a2/a3) should be separated by another A-PSDU. • Topic2: Sub frame header should have CRC and develop one mechanism can find next correct sub frame header when current one is broken if topic 1 is applied. • Reason: make sure this header is right. One sub frame header is fail, all the A-MSDU is fail. • Benefit: One sub-frame header is fail, but the rest of sub-frame can still help. • Drawback: Implementation overload. John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

  30. Summary • More Use and Application cases need to be considered for a full analysis of proposals. This analysis needs to be scheduled. • Both TGn Sync and WWiSE proposals have strengths and weaknesses. We recommend an effort to resolve these through some form of merger. • The market should get as strong and technologically advanced a standard as possible to promote the next wave of consumer and in-premise distribution beyond traditional LAN devices John Egan, Rodger Tseng, Albert Liu, Infineon Technologies

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