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OFDMA performance in 11ax

This presentation delves into the enhanced OFDMA performance in simulation cases, revealing implications on throughput, latency, and scheduler efficiency. Updated simulation setup and results are presented in detail, showcasing improvement in various traffic scenarios.

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OFDMA performance in 11ax

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  1. OFDMA performance in 11ax Date: 2015-11-16 Authors: Suhwook Kim, LG Electronics

  2. Introduction • We addressed OFDMA performance using PHY/MAC integrated simulator in previous meeting • OFDMA shows better performance in our simulation cases • After previous meeting, we enhanced OFDMA simulator based on discussion in previous meeting • We will address new OFDMA simulation results in this presentation Suhwook Kim, LG Electronics

  3. Previous works • We addressed OFDMA performance based on • DL only and UL only traffic direction case • single BSS topology and residential scenario • high rate and low rate CBR traffic case • Performance gain of OFDMA depends on topology, traffic direction, and traffic load • OFDMA shows 20~80% throughput gain in high loaded traffic • In low traffic load, throughput gain is limited • In general, OFDMA shows better latency performance • Random scheduler and queue length scheduler show similar performance • Because scheduler was very simple and AP’s queue wasn’t manageable Suhwook Kim, LG Electronics

  4. Simulation enhancement • AP Queue handling • Before: AP’s queue can be fully buffered by data frames for a certain receiver • After: Number of queued frame for a certain receiver is limited • Traffic direction • Before: UL only or DL only • After: DL & UL mixed traffic • Trigger frame generation • Before: Trigger frame is generated every short time in UL only case (AP only transmitted trigger frame) • After: Trigger frame is generated every Ttrg period and trigger frame has priority over data frame Suhwook Kim, LG Electronics

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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 → No Tput gain • UL OFDMA transmission → UL interference ↑ → DL PER ↑ • No STA’s contending → No UL Collision → UL PER ↓ Suhwook Kim, LG Electronics

  12. 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 STAs 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

  13. 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 STAs case) • Very low rate traffic → No Tput gain • UL OFDMA transmission → UL interference↑ → DL PER ↑ • No STA’s contending → No UL Collision → UL PER ↓ Suhwook Kim, LG Electronics

  14. 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 • Throughputs are similar • Long Ttrg → UL interference↓ → DL/UL PER ↓ Suhwook Kim, LG Electronics

  15. 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 • Throughputs are similar • UL TXOP length↓ → UL interference↓ → DL/UL PER ↓ Suhwook Kim, LG Electronics

  16. 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

  17. 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

  18. 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 • More sophisticated scheduler • Contending by STAs and CCA after trigger frame • MU-RTS/CTS Suhwook Kim, LG Electronics

  19. Conclusion • We addressed OFDMA performance on DL and UL mixed traffic case • OFDMA still show throughput/latency gain except very low rate traffic case • Also we addressed trend of OFDMA performance on variable trigger frame generation periods and UL TXOP lengths • T rigger frame generation period and UL TXOP length have an effect on DL/UL performance Suhwook Kim, LG Electronics

  20. 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

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

  22. 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

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

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

  25. 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

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

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

  28. 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

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

  30. 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

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

  32. 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

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

  34. 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

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

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