Cyclic Shift Values for Legacy Portion Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Cyclic Shift Values for Legacy Portion Date: 2010-09-13 Authors: Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Outline Introduction Simulation Results Summary Proposed CSD Values Sept 2010 Outline Introduction Simulation Results Summary Proposed CSD Values Strawpolls Leonardo Lanante Jr./Kyushu Institute of Technology

Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Introduction Last July 2010 TGac meeting, it was agreed that the CSD for the　non-VHT portion of 11ac be constrained to within 200ns for any number of antennas [1]. When the number of antennas is less than or equal to 4, 11ac uses the 11n legacy CSD values. This presentation is a proposal for CSD values when the number of antennas is more than 4. Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Methodology CSD is a simple way to avoid unintentional beamforming that causes large variations in receive power. For NTx<5, 11n values were used for 11ac For NTx=5, the 11n values can be naturally extended to [0 -50ns -100ns -150ns -200ns] To obtain CSD values for NTx=[6, 7, 8], we performed a linear full search from all possible sequences with 25ns resolution 1Tx 2Tx 3Tx 4Tx 1 2 -200ns 3 -100ns 4 -50ns -150ns Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Cost Function Definition Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Cost Function Definition 99% The smaller R is, the lesser variation in the computed L-STF Power. 1% R R= Fluctuation of computed L-STF Power [2] Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Full Search Method For NTx=[6, 7, 8], we search for CSD sequence with least R The CSD value search used a resolution of 25ns All CSD values are distinct per antenna The values are obtained from the base sequence CSD_MAIN= [0 25 50 75 100 125 150 175 200]. Note: Corresponding CSD values are in ns and negative) Procedure to pick a CSD_SEQ for NTx=6,7,8 CSD_SEQ = [ 0 25 50 125 ….. 150 200 ] The rest of NTx-1 elements come from the non-zero values of CSD_MAIN. One combination of NTx-1 elements can be permuted to produce a set of CSD_SEQs The first element is always zero Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Example: CSD_SEQs for NTx=6 Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Example: CSD_SEQs for NTx=6 CSD_MAIN= [0 25 50 75 100 125 150 175 200] [0 25 50 75 100 125] [0 25 50 75 125 100] Total of 120 distinct permutations [0 125 100 75 50 25] Combination Set 1 [0 25 50 75 100 125] [0 25 50 75 100 150] [0 25 50 75 150 100] Total of 120 distinct permutations [0 150 100 75 50 25] Each combination set has distinct elements Combination Set 2 [0 25 50 75 100 150] Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Example: CSD_SEQs for NTx=6 Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Example: CSD_SEQs for NTx=6 [0 75 100 125 150 200] [0 75 100 125 200 150] Total of 120 distinct permutations [0 200 150 125 100 75] Combination Set 55 [0 75 100 125 150 200] [0 100 125 150 175 200] Total of 120 distinct permutations [0 200 175 150 125 100] Combination Set 56 [0 100 125 150 175 200] # Combination Sets = # Permutations = (NTx-1)! Total Possible Sequences = # Combination Sets x # Permutations Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Simulation Results for NTx=6 Month Year doc.: IEEE 802.11-yy/xxxxr0 Simulation Results for NTx=6 Sept 2010 Effect of Permutation ( Combination Sets Superimposed) Average per color Channel B Channel D RminB RminD Red – Combinations sets with maximum of 125 (1 set) Blue – Combinations sets with maximum of 150 (5 sets) Green – Combinations sets with maximum of 200 (35 sets) Lower Ave. Fluctuation RminB = CSD_SEQ with minimum R in Channel Model B RminD = CSD_SEQ with minimum R in Channel Model D Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Simulation Results for NTx=7 Month Year doc.: IEEE 802.11-yy/xxxxr0 Simulation Results for NTx=7 Sept 2010 Effect of Permutation (Combination Sets Superimposed) Average per color Channel B Channel D RminB RminD Red – Combinations sets with maximum of 150 (1 sets ) Blue – Combinations sets with maximum of 175 (6 sets) Green – Combinations sets with maximum of 200 (21 sets) Lower Ave. Fluctuation RminB = CSD_SEQ with minimum R in Channel Model B RminD = CSD_SEQ with minimum R in Channel Model D Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Simulation Results for NTx=8 Month Year doc.: IEEE 802.11-yy/xxxxr0 Simulation Results for NTx=8 Sept 2010 Effect of Permutation (Combination Sets Superimposed) Average per color Channel B Channel D RminB RminD Blue – Combinations sets with maximum of 175 (1 set) Green – Combinations sets with maximum of 200 (7 sets) Lower Ave. Fluctuation RminB = CSD_SEQ with minimum R in Channel Model B RminD = CSD_SEQ with minimum R in Channel Model D Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Sept 2010 Observations In general, relative performance of any CSD_SEQ compared to another depends on the channel model (i.e. Channel B or D) Absolutely optimal CSD_SEQ also changes depending on the channel model Better overall performance can be obtained if CSD_SEQ is exactly within 200ns (i.e. it belongs in a combination set that includes the element 200). Based on this observations, we are proposing the following CSD values … Leonardo Lanante Jr./Kyushu Institute of Technology

Proposed CSD Values for non-VHT Portion Month Year doc.: IEEE 802.11-yy/xxxxr0 Sept 2010 Proposed CSD Values for non-VHT Portion Number of TX chains Cyclic Shift for TX chain 1 (ns) Cyclic Shift for TX chain 2 (ns) Cyclic Shift for TX chain 3 (ns) Cyclic Shift for TX chain 4 (ns) Cyclic Shift for TX chain 5 (ns) Cyclic Shift for TX chain 6 (ns) Cyclic Shift for TX chain 7 (ns) Cyclic Shift for TX chain 8 (ns) 1 2 -200 3 -100 4 -50 -150 5 6 -25 7 -75 8 -125 Leonardo Lanante Jr./Kyushu Institute of Technology John Doe, Some Company

Sept 2010 Strawpoll #1 Do you support using the CSD values of [0 -50ns -100ns -150ns -200ns], natural extension from 11n CSD, for five transmit antennas in the non-VHT portion of 11ac mixed mode packet and updating the specification framework accordingly? Yes No Abstain Leonardo Lanante Jr./Kyushu Institute of Technology

Sept 2010 Strawpoll #2 Do you support using the CSD values, simple linear incremental values including -200ns, in slide 11 for 6, 7, and 8 antennas in the non-VHT portion of 11ac mixed mode packet and updating the specification framework accordingly ? Yes No Abstain Leonardo Lanante Jr./Kyushu Institute of Technology

Sept 2010 References [1] – Yung-Szu Tu et. al, Cyclic Shift For More Than 4 Antennas in Non-VHT Portion. doc.:802.11-10/0916r0 [2]- Aoki et. al, Preamble Structure for MIMO-OFDM WLAN Systems Based on IEEE 802.11A, PIMRC 2006 Leonardo Lanante Jr./Kyushu Institute of Technology