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OFDMA performance in 11ax

This presentation provides an update on the performance of OFDMA in 11ax, focusing on throughput and latency. It discusses simulation environments, setup, parameters, topology, and various simulation cases and their results.

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OFDMA performance in 11ax

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  1. OFDMA performance in 11ax Date:2015-11-12 Authors: Suhwook Kim, LG Electronics

  2. Introduction • The key feature of 11ax is OFDMA. • In the previous meeting, we initially addressed OFDMA performance using PHY/MAC integrated simulator • OFDMA shows better performance in throughput and latency • This presentation provides update on it. Suhwook Kim, LG Electronics

  3. Update on Simulation Environments • Traffic direction • UL only or DL only  DL & UL mixed traffic • Trigger frame generation • Trigger frame is generated in UL only case • Trigger frame is generated every Ttrg period and trigger frame has priority over DL data frame • AP Queue handling • AP’s queue can be fully buffered by data frames for a certain receiver  Number of queued frame for a certain receiver is limited Suhwook Kim, LG Electronics

  4. Simulation Setup: Scheduler • Scheduling resource • Maximum allocation per one station is 1 RU • 1 RU: 242-tone (total 4 RUs in 80 MHz) • Scheduling policy • Random: AP selects STAs randomly • In DL case, • primary destination is fixed (Head of AP’s queue) • frame length is determined by A-MPDU length to primary destination (legacy spec rule) Suhwook Kim, LG Electronics

  5. Simulation Setup: Frame length and padding • UL • UL TXOP length is always fixed in one simulation drop • DL • DL TXOP length is variable (depends on primary destination) DL TXOP Length UL TXOP Length Suhwook Kim, LG Electronics

  6. Simulation Setup: Parameters * The transmission latency is measured from the time that MAC receives a packet till the time that PHY starts transmitting. Suhwook Kim, LG Electronics

  7. Topology • Topology description • 20 APs (Fixed location: center of room) • 4 or 10 STAs per one AP (Random location) • Simulation setting • Open Loop Link Adaption [3] • Channelization: Fixed channelization CH1 CH2 CH3 Suhwook Kim, LG Electronics

  8. Simulation cases • Case 1: 4 STAs, DL/UL 10 Mbps • Case 2: 4 STAs, DL/UL 1 Mbps • Case 3: 10 STAs, DL/UL 4 Mbps • Case 4: 10 STAs, DL/UL 1 Mbps • Case 5: 4 STAs, DL/UL 10 Mbps, Ttrg varies • Case 6: 4 STAs, DL/UL 10 Mbps, UL TXOP length varies • Case 7: 4 STAs, DL/UL 50 Mbps, Ttrg varies • Case 8: 4 STAs, DL/UL 50 Mbps, UL TXOP length varies Suhwook Kim, LG Electronics

  9. Simulation Result – Case 1 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 10 Mbps, UL 10 Mbps (Medium level) • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • No STA’s contending → AP can get TXOP easily → DL Tput ↑ • No STA’s contending → No UL Collision → UL Tput ↑ & UL PER ↓ Suhwook Kim, LG Electronics

  10. Simulation Result – Case 2 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 1 Mbps, UL 1 Mbps (Low level) • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • Very low rate traffic → meet the maximum Suhwook Kim, LG Electronics

  11. Simulation Result – Case 3 • 10 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 4 Mbps, UL 4 Mbps (Medium level) • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Similar with Case 1 (4 STA case) • No STA’s contending → AP can get TXOP easily → DL Tput ↑ • No STA’s contending → No UL Collision → UL Tput ↑ & UL PER ↓ Suhwook Kim, LG Electronics

  12. Simulation Result – Case 4 • 10 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 1 Mbps, UL 1 Mbps (Low level) • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Similar with Case 2 (4 STA case) • Very low rate traffic → meet the maximum Suhwook Kim, LG Electronics

  13. Simulation Result – Case 5 • 4 STAs for 1 AP • Data rate: DL 10 Mbps, UL 10 Mbps (Medium level) • Ttrg : 10, 15, 20 msec • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • Ttrg of 20msec is enough for offered UL traffic. • DL has more opportunity when Ttrg increases Suhwook Kim, LG Electronics

  14. Simulation Result – Case 6 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 10 Mbps, UL 10 Mbps (Medium level) • Max DL TXOP: 5 msec, UL TXOP: 3, 4, 5 msec • Observation • Ttrg of 20msec is enough for offered UL traffic. • DL has more opportunity when Ttrg increases Suhwook Kim, LG Electronics

  15. Simulation Result – Case 7 • 4 STAs for 1 AP • Data rate: DL 50 Mbps, UL 50 Mbps (Full buffered) • Ttrg : 10, 15, 20, 25 msec • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • Long Ttrg → DL TX ↑ → DL Tput ↑ • Long Ttrg → UL TX ↓ → UL Tput ↓ Suhwook Kim, LG Electronics

  16. Simulation Result – Case 8 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 50 Mbps, UL 50 Mbps (Full buffered) • Max DL TXOP: 5 msec, UL TXOP: 3, 4, 5 msec • Observation • UL TXOP length↓ → DL TX ↑ → DL Tput ↑ • UL TXOP length↓ → UL TX ↓ → UL Tput ↓ Suhwook Kim, LG Electronics

  17. Next Step • Following items will be added to OFDMA simulation • Different resource unit (26 tones, 52 tones, 106 tones, 484 tones) • Short packet traffic • Feedback modeling • Other schedulers • Contending by STAs and CCA after trigger frame • MU-RTS/CTS • Different scenarios/traffic model Suhwook Kim, LG Electronics

  18. Conclusion • We addressed OFDMA performance on DL and UL mixed traffic case • OFDMA generally show throughput/latency gain • We initially addressed trend of OFDMA performance on variable trigger frame generation period and UL TXOP length • T rigger frame generation period and UL TXOP length have an effect on DL/UL performance Suhwook Kim, LG Electronics

  19. Reference • [1] 11-15/0132r7 Spec Framework • [2] 11-14/0980r14 Simulation Scenarios • [3] 11-14/620r0 link adaptation for PHY SLS calibration • [4] 11-14/0571r10 11ax Evaluation Methodology Suhwook Kim, LG Electronics

  20. Backup Slide- Latency analysis Suhwook Kim, LG Electronics

  21. Simulation Result – Case 1 & 2 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 1/10 Mbps, UL 1/10 Mbps • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • Medium rate → AP can get TXOP easily → DL Latency ↓ • Medium rate → No UL collision → UL Latency ↓ • Very low rate → Inefficient trigger frame transmission ↑ → DL Data TX ↓ → DL Latency ↑ Suhwook Kim, LG Electronics

  22. Simulation Result – Case 1 Suhwook Kim, LG Electronics

  23. Simulation Result – Case 2 Suhwook Kim, LG Electronics

  24. Simulation Result – Case 3 & 4 • 10 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 1/4 Mbps, UL 1/4 Mbps • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Similar with Case 1&2 (4 STA case) • Medium rate → AP can get TXOP easily → DL Latency ↓ • Medium rate → No UL collision → UL Latency ↓ • Very low rate → Inefficient trigger frame transmission ↑ → DL Data TX ↓ → DL Latency ↑ Suhwook Kim, LG Electronics

  25. Simulation Result – Case 3 Suhwook Kim, LG Electronics

  26. Simulation Result – Case 4 Suhwook Kim, LG Electronics

  27. Simulation Result – Case 5 • 4 STAs for 1 AP • Data rate: DL 10 Mbps, UL 10 Mbps • Ttrg : 10, 15, 20 msec • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • Long Ttrg → DL TX ↑ → DL Latency ↓ • Long Ttrg → UL TX ↓ → UL Latency ↑ Suhwook Kim, LG Electronics

  28. Simulation Result – Case 5 Suhwook Kim, LG Electronics

  29. Simulation Result – Case 6 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 10 Mbps, UL 10 Mbps • Max DL TXOP: 5 msec, UL TXOP: 3, 4, 5 msec • Observation • UL TXOP length↓ → DL TX ↑ → DL Latency ↓ • UL PER↓ → UL Retransmission ↓ → UL Latency ↓ Suhwook Kim, LG Electronics

  30. Simulation Result – Case 6 Suhwook Kim, LG Electronics

  31. Simulation Result – Case 7 • 4 STAs for 1 AP • Data rate: DL 50 Mbps, UL 50 Mbps • Ttrg : 10, 15, 20, 25 msec • Max DL TXOP: 5 msec, UL TXOP: 5 msec • Observation • Long Ttrg → DL TX ↑ → DL Latency ↓ • Long Ttrg → UL TX ↓ → UL Latency ↑ Suhwook Kim, LG Electronics

  32. Simulation Result – Case 7 Suhwook Kim, LG Electronics

  33. Simulation Result – Case 8 • 4 STAs for 1 AP, Ttrg = 10 msec • Data rate: DL 50 Mbps, UL 50 Mbps • Max DL TXOP: 5 msec, UL TXOP: 3, 4, 5 msec • Observation • UL TXOP length↓ → DL TX ↑ → DL Latency ↓ • UL TXOP length↓ → UL TX ↓ → UL Latency ↑ Suhwook Kim, LG Electronics

  34. Simulation Result – Case 8 Suhwook Kim, LG Electronics

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