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Effective Subcarrier Assignment for DL-OFDMA

Explore how flexible subcarrier assignment in DL-OFDMA technology can lead to better efficiency in data transmission for WLAN networks. The study delves into the allocation of subcarriers based on required OFDM symbols for different destinations, optimizing resource utilization, and minimizing padding bits. The proposed scheme aims to enhance resource utilization and improve overall network performance in DL-OFDMA environments.

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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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