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Doc.: IEEE 802.11-09/0847r1 Submission Slide 1Leonardo Lanante, Ochi Lab, KIT November 2009 IEEE802.11ac Preamble with Legacy 802.11a/n Backward Compatibility.

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Presentation on theme: "Doc.: IEEE 802.11-09/0847r1 Submission Slide 1Leonardo Lanante, Ochi Lab, KIT November 2009 IEEE802.11ac Preamble with Legacy 802.11a/n Backward Compatibility."— Presentation transcript:

1 doc.: IEEE /0847r1 Submission Slide 1Leonardo Lanante, Ochi Lab, KIT November 2009 IEEE802.11ac Preamble with Legacy a/n Backward Compatibility Date: Authors:

2 doc.: IEEE /0847r1 Submission Slide 2Leonardo Lanante, Ochi Lab, KIT November 2009 Outline I.Introduction II. Proposed Preamble Format (modified) III. Preamble Waveform IV. Compatibility Simulations (added) V.PAPR (modified) VI.Preamble Efficiency VII. Conclusion

3 doc.: IEEE /0847r1 Submission Slide 3Leonardo Lanante, Ochi Lab, KIT November 2009 I. Introduction Functional requirements for TGac. A)System Performance 1.Shall operate in 5GHz frequency band 2.At least 1Gbps at MAC SAPs utilizing 80MHz 3.At least 500Mbps for Single STA 4.Spectral efficiency at least 7.5 bps/Hz B)Shall ensure backward compatibility with IEEE a/n. C)Enable coexistence and spectrum sharing with IEEE a/n. D)Compliance to PAR Doc.IEEE /0304r0 March 2009

4 doc.: IEEE /0847r1 Submission Slide 4Leonardo Lanante, Ochi Lab, KIT November 2009 II. Proposed Preamble Main Features –Uses 80MHz channel and meets all functional requirements for a VHT preamble –Three preamble modes to minimize overhead –Seamless upgrade from n preamble –Almost identical PAPR characteristics with n –Comparable Preamble Efficiency to n

5 doc.: IEEE /0847r1 Submission Slide 5Leonardo Lanante, Ochi Lab, KIT November 2009 Proposed Preamble Modes A)Mixed 11a/n Mode 1.56us duration 2.Backward compatible with a/n B)Mixed 11n Mode 1.44us duration 2.Backward compatible with n C)VHT Greenfield Mode 1.36us duration 2.VHT only mode

6 doc.: IEEE /0847r1 Submission Slide 6Leonardo Lanante, Ochi Lab, KIT November 2009 A) Mixed 11a/n Mode Frame Format Mixed 11a/n Mode: Backward compatible with IEEE802.11a/n Duration=56μs * L-STF L-LTF L-SIG HT-SIG VHT-SIG VHT STF VHT LTF1 VHT LTF4 VHT LTF4 Data 8μs8μs8μs8μs4μs4μs8μs8μs8μs8μs4μs4μs4μs per LTF4/3.6μs per Data * 4 spatial streams L-STF L-LTF L-SIG HT-SIG HT STF HT LTF1 HT LTF4 HT LTF4 Data 8μs8μs8μs8μs4μs4μs8μs8μs4μs4μs4μs per LTF4/3.6μs per Data Duration=48μs * n Mixed Mode Preamble A new SIG field is defined to accommodate changes in VHT while maintaining compatibility

7 doc.: IEEE /0847r1 Submission Slide 7Leonardo Lanante, Ochi Lab, KIT November 2009 Subcarrier Extension for 80 MHz Channel n 40MHz case S = subcarrier pattern for 20MHz system -Direct Extension of subcarriers results in best compatibility with 11a/n devices -The phase shift vector [1 j e jθ je jθ ] results in a high PAPR preamble for any value of θ Direct Extension 80MHz e jθ (S)jSSe jθ (jS) SjS

8 doc.: IEEE /0847r1 Submission Slide 8Leonardo Lanante, Ochi Lab, KIT November 2009 Proposed Phase Rotation for 80 MHz Channel to Maintain Low PAPR Proposed scheme for 80MHz -The phases in the proposed scheme [1 j 1 –j] were chosen to give low PAPR properties -All 80MHz symbols need to be phase shifted by the same scheme either for compatibility or for PAPR reduction Direct Extension 80MHz e jθ (S)jSS S S -jS e jθ (jS)

9 doc.: IEEE /0847r1 Submission Slide 9Leonardo Lanante, Ochi Lab, KIT November 2009 Legacy – Short Training Field L-STF L-LTFL-SIGHT-SIGVHT-SIG VHT STF VHT LTF1 VHT LTF4 Data Subcarriers # L-STF 20MHz

10 doc.: IEEE /0847r1 Submission Slide 10Leonardo Lanante, Ochi Lab, KIT November 2009 Legacy - Long Training Field Subcarriers # L-STFL-LTFL-SIGHT-SIGVHT-SIG VHT STF VHT LTF1 VHT LTF4 Data L-LTF 20MHz

11 doc.: IEEE /0847r1 Submission Slide 11Leonardo Lanante, Ochi Lab, KIT November 2009 Legacy - SIGNAL Field Subcarriers # L-SIG 20MHz L-SIGGI s 3.2 s s 0.8 s L-STFL-LTFL-SIGHT-SIGVHT-SIG VHT STF VHT LTF1 VHT LTF4 Data

12 doc.: IEEE /0847r1 Submission Slide 12Leonardo Lanante, Ochi Lab, KIT November 2009 VHT – SIGNAL Field 64 options of MCS octet of data LENGTH = 2 X n. CRC protected. STBCShort GIReserved one STBC BW LSB BW MSB LENGTH should be increased by one bit to maintain preamble efficiency lost with the use of 80MHz channel L-STFL-LTFL-SIGHT-SIGVHT-SIG VHT STF VHT LTF1 VHT LTF4 Data

13 doc.: IEEE /0847r1 Submission Slide 13Leonardo Lanante, Ochi Lab, KIT November 2009 B) Mixed 11n Mode Frame Format Mixed 11n Mode: Backward compatibility with IEEE802.11n Duration=44μs * HT-STF HT-LTF HT-SIG VHT-SIG VHT LTF2 VHT LTF4 VHT LTF4 Data 8μs8μs8μs8μs8μs8μs8μs8μs4μs per LTF4/3.6μs per Data The difference with n greenfield preamble is the additional SIG symbol n Greenfield Preamble Duration=36μs * HT-STF HT-LTF1 HT-SIG HT LTF2 HT LTF4 HT LTF4 Data 8μs8μs8μs8μs8μs8μs4μs per LTF4/3.6μs per Data * 4 spatial streams

14 doc.: IEEE /0847r1 Submission Slide 14Leonardo Lanante, Ochi Lab, KIT November 2009 C) VHT Greenfield Mode Frame Format VHT Greenfield Mode: No backward compatibility with IEEE802.11a/n Duration=36μs* VHT-STF VHT-LTF1 VHT-SIG VHT LTF2 VHT LTF4 VHT LTF4 Data 8μs8μs8μs8μs8μs8μs4μs per LTF4/3.6μs per Data -Same purpose as the n greenfield format preamble

15 doc.: IEEE /0847r1 Submission Slide 15Leonardo Lanante, Ochi Lab, KIT November 2009 III. Preamble Waveform s Time ( ) L-STFL-LTF VHT- STF VHT- LTF1 VHT- LTF2 VHT- LTF3 VHT- LTF4 L- SIG HT- SIG1 HT- SIG2 VHT- SIG1 VHT- SIG2

16 doc.: IEEE /0847r1 Submission Slide 16Leonardo Lanante, Ochi Lab, KIT November 2009 IV. Co-existence Simulations Co-existence with 11a/n device at any 20MHz channel 80 MHz device S jS S -jS Proposed 80MHz format 11a/n devices at any 20MHz channel can properly detect the preamble a=legacy a/HT STS, LTS, etc… S jS S -jS 20 MHz device 80MHz 20MHz

17 doc.: IEEE /0847r1 Submission Slide 17Leonardo Lanante, Ochi Lab, KIT November 2009 IV. Co-existence Simulations Co-existence with 11n device at 40MHz channel 80 MHz device S jS S -jS Proposed 80MHz format 11n devices at the UPPER 40 MHz channel expects [1 j] subcarrier rotation and has a possible compatibility issue. a=legacy a/HT STS, LTS, etc… S jS S -jS 40 MHz device 80MHz 40MHz 40 MHz device 40MHz

18 doc.: IEEE /0847r1 Submission Slide 18Leonardo Lanante, Ochi Lab, KIT November 2009 Simulation Setup All receivers (40MHz HT) and transmitters (80MHz VHT) have 4 antennas Channel Model –AWGN –TGn channel model B –TGn channel model D Simulation tests –Frame Synchronization/Preamble Detection Auto-correlation Cross-correlation –Channel Estimation and SIG field Detection

19 doc.: IEEE /0847r1 Submission Slide 19Leonardo Lanante, Ochi Lab, KIT November 2009 Frame Synchronization/Preamble Detection SISO Case cross-correlation Autocorrelation Based Frame Synchronization algorithm is not affected because it doesnt use an expected reference sequence. Cross-correlation of 40Mhz 11n STS Cross-correlation of 40Mhz 11n STS when a [1 –j] phase rotated STS symbol is received

20 doc.: IEEE /0847r1 Submission Slide 20Leonardo Lanante, Ochi Lab, KIT November 2009 Frame Synchronization/Preamble Detection -Error differences in the upper and lower 40Mhz channels is indiscernible -Performance only differs whether one uses auto-correlation or cross-correlation algorithm.

21 doc.: IEEE /0847r1 Submission Slide 21Leonardo Lanante, Ochi Lab, KIT November 2009 Frame Synchronization/Preamble Detection Error differences in the upper and lower 40MHz channels is indiscernible

22 doc.: IEEE /0847r1 Submission Slide 22Leonardo Lanante, Ochi Lab, KIT November 2009 Channel Estimation and SIG field detection Because Data symbols also undergo the same subcarrier phase shifts, SIG detection is unaffected by our proposed phase shift method Synchronization errors were also counted as SIG-field symbol error Error differences in the upper and lower 40MHz channels is indiscernible

23 doc.: IEEE /0847r1 Submission Slide 23Leonardo Lanante, Ochi Lab, KIT November 2009 Channel Estimation and SIG field detection Error differences in the upper and lower 40MHz channels is indiscernible

24 doc.: IEEE /0847r1 Submission Slide 24Leonardo Lanante, Ochi Lab, KIT November 2009 V. PAPR FieldNyquist Sampled4x oversampled n 11ac- Proposed 11ac- Direct n11ac- Proposed 11ac- Direct L-STF L-LTF HT-LTF

25 doc.: IEEE /0847r1 Submission Slide 25Leonardo Lanante, Ochi Lab, KIT November 2009 VI. Preamble Efficiency The preamble efficiency is defined as

26 doc.: IEEE /0847r1 Submission Slide 26Leonardo Lanante, Ochi Lab, KIT November 2009 Conclusion We have been developing an 80MHz BW WLAN preamble which has backward compatibility with IEEE802.11a/n system. Our simulation results confirm our proposed preambles backward compatibility with n 40MHz devices The proposed preamble has comparable efficiency compared to IEEE802.11ns preamble. The proposed preamble has lower PAPR compared with IEEE802.11ns preamble.

27 doc.: IEEE /0847r1 Submission Slide 27Leonardo Lanante, Ochi Lab, KIT November 2009 References 1.E. Perahia, IEEE P Wireless LANs: VHT below 6GHz PAR Plus 5Cs, doc.:IEEE /0807r4. 2.Supplement to IEEE STANDARD for Information Technology – Telecommunications and Information Exchange between Systems - Local and Metropolitan Area Networks - Specific Requirements, IEEE Std a- 1999(R2003), June Draft STANDARD for Information Technology – Telecommunications and Information Exchange between Systems - Local and Metropolitan Area Networks - Specific Requirements, IEEE P802.11n./D9.0, March Peter L and Minho C, TGac Functional Requirements Rev.0, doc.:IEEE /0304r0. 5.Rolf de V, ac Usage Models Document, doc.:IEEE /0161r2. 6.Minho C and Peter L, Proposal for TGac Evaluation Methodology, doc.:IEEE /0376r1.


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