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Effective Subcarrier Assignment for DL-OFDMA

Effective Subcarrier Assignment for DL-OFDMA. Date: 2015-03-06. Authors:. Background. DL-OFDMA is one of promising technologies for better efficiency in WLAN. DL-OFDMA PPDU will include data for plural STAs. These data have various sizes and will be sent in various MCSs for each destination.

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Effective Subcarrier Assignment for DL-OFDMA

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  1. EffectiveSubcarrierAssignmentforDL-OFDMA • Date:2015-03-06 Authors: K. Yunoki & B. Zhao, KDDI R&D Labs.

  2. Background • DL-OFDMA is one of promising technologies for better efficiency in WLAN. • DL-OFDMA PPDU will includedata forpluralSTAs. These data have various sizes and will be sent in various MCSs for each destination. • The following slides will show how theefficiency is in an OFDMA PPDU. K. Yunoki & B. Zhao, KDDI R&D Labs.

  3. Assumption -1 • DL-data destined to 4 STAs are assumed to be packed in an OFDMA PPDU in 20MHzBW as below: • 5MHzBW is assigned for each destination. K. Yunoki & B. Zhao, KDDI R&D Labs.

  4. Flame Configuration-1 SL (Symbol Length)=number of consecutive OFDM symbols Just data part was considered. • There will be big differences in requiredsymbollengths among destinations when assigned subcarriers are 52 fixed for each destination. 50B MCS=0 STA1 : 52 subcarriers 16 SL padding 50B MCS=7 Padding = 65% STA2 : 52 subcarriers 2 SL 200B MCS=0 STA3 : 52 subcarriers 62 SL 200B MCS=7 padding STA4 : 52 subcarriers 7 SL Time K. Yunoki & B. Zhao, KDDI R&D Labs.

  5. Assumption -2 • DL-data destined to 3 STAs are assumed to be packed in an OFDMA PPDU in 20MHzBW as below: • 10MHzBW is assigned for STA3 in this assumption. K. Yunoki & B. Zhao, KDDI R&D Labs.

  6. Flame Configuration-2 • Padding bits are greatly reduced comparing with Assumption-1. However, differences ofrequiredsymbollengthsamong destinations are still big. 50B MCS=0 STA1 : 52 subcarriers 16 SL padding 50B MCS=7 STA2 : 52 subcarriers 2 SL Padding = 35% 200B MCS=0 STA3 : 104 subcarriers 31 SL Time K. Yunoki & B. Zhao, KDDI R&D Labs.

  7. Flexible Subcarrier Assignment(1)(Assumption-1) • Number of subcarriers will be decided based on required OFDM symbols for data for each destination as below figure: • This schemewillachievemoreefficientresourceutilization. 22 SL 50B MCS=0 to STA1 37 subcarriers STA1 : 5 subcarriers to STA2 padding Padding: 65%  4% 50B MCS=7 to STA3 STA2 : 8 SL 200B MCS=0 151 subcarriers STA3 : Required SL: 62  22 200B MCS=7 STA4 : 15 subcarriers to STA4 K. Yunoki & B. Zhao, KDDI R&D Labs.

  8. Flexible Subcarrier Assignment(2) • A STA ID is identified in HEheader part of each subcarrier. HE header Data part BW STA ID MCS : Read data 〜 K. Yunoki & B. Zhao, KDDI R&D Labs.

  9. Assumption -3 • DL-data destined to 4 STAs are assumed. • Similar data size and MCS for 4 STAs are considered as below: K. Yunoki & B. Zhao, KDDI R&D Labs.

  10. Comparison(Assumption-3) • Fixed SC assignment • Flexible SC assignment 52SC 54SC 11 SL 52SC pad 42SC 8 SL 52SC 64SC 13 SL 52SC pad 10 SL 48SC 13 SL 10 SL (0.8us+3.2us*4) * 13 = 176.8us (0.8us+3.2us*4) * 10 = 136.0us Padding = 24.0% Padding = 1.3% K. Yunoki & B. Zhao, KDDI R&D Labs.

  11. Pros and Cons(Subcarrier Assignment for DL-OFDMA) Flexible subcarrier assignment should be considered to meet TGax objectives. K. Yunoki & B. Zhao, KDDI R&D Labs.

  12. Summary • Flexible subcarrier assignment for DL-OFDMA was proposed. • This scheme willrealizemoreeffectiveresourceutilization. • Further studies are required for detailed mechanism definitions. K. Yunoki & B. Zhao, KDDI R&D Labs.

  13. StrawPoll • Do you agree to add the following text into SFD? • 4.Multi-user (MU) features • Theamendmentshallallow toassignflexible number of subcarriersforeach destination in DL-OFDMA PPDU. • Y/N/A= K. Yunoki & B. Zhao, KDDI R&D Labs.

  14. References • 11-15/0132r2,SpecFrameworkDocument • 11-15/0066r0, Downlink OFDMA Protocol Design K. Yunoki & B. Zhao, KDDI R&D Labs.

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