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IEEE 802.11e Performance Evaluation

IEEE 802.11e Performance Evaluation. Javier del Prado and Patrick Wienert Philips javier.delprado@philips.com. Outline. Goal Overview of Protocols Evaluated Simulation Results Conclusions References. Goal.

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IEEE 802.11e Performance Evaluation

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  1. IEEE 802.11e Performance Evaluation Javier del Prado and Patrick Wienert Philips javier.delprado@philips.com Javier del Prado et al. Philips

  2. Outline • Goal • Overview of Protocols Evaluated • Simulation Results • Conclusions • References Javier del Prado et al. Philips

  3. Goal • Evaluate the Throughput Performance of IEEE 802.11e MAC protocols as a function of the Frame Size and the Number of Stations • Verify that the Usage Scenarios defined in 11-03-802 are implementable Javier del Prado et al. Philips

  4. Overview of Protocols Evaluated Frame exchanges used in the simulation Javier del Prado et al. Philips

  5. Access Point has frames for Station Beacon Beacon Backoff Backoff Frame 2 Access Point DIFS DIFS Busy SIFS SIFS t Ack Ack Wireless Station t Beacon Interval. Typical value = 100 ms • DCF Frame 1 Javier del Prado et al. Philips

  6. Beacon Beacon Frame 2 Backoff Backoff Access Point AIFS AIFS SIFS SIFS t Ack Ack Wireless Station t TXOP Bursting (Reduces Backoff Overhead) • EDCA t < EDCA TXOP limit Busy Frame 1 Javier del Prado et al. Philips

  7. Backoff Backoff Access Point AIFS AIFS Wireless Station SIFS SIFS SIFS SIFS • EDCA with No ACK t < EDCA TXOP limit t < EDCA TXOP limit Frame 2 Frame 3 Frame 1 Frame 2 Frame 3 Busy Frame 1 t t Javier del Prado et al. Philips

  8. Access Point SIFS SIFS SIFS Wireless Station Piggybacking (Reduces Poll and Ack Overheads) PIFS PIFS UPLINK TXOP DOWNLINK TXOP • HCCA Polled TXOP limit Downlink TXOP limit Beacon Poll + Data Ack Data Busy Data Ack t SIFS SIFS SIFS Ack Data Data + Ack t Javier del Prado et al. Philips

  9. Access Point SIFS Wireless Station PIFS PIFS UPLINK TXOP DOWNLINK TXOP • HCCA with NO ACK Polled TXOP limit Downlink TXOP limit Beacon Poll + Data Data Data Busy Data t SIFS SIFS SIFS SIFS Data Data Data t Javier del Prado et al. Philips

  10. Simulation Results Javier del Prado et al. Philips

  11. BriarLAN 10.0 Simulator • Based on OPNET 10.0 PL2 (October 2003) • Model Library: 10-24-2003 • Functionality • Full 802.11 Legacy MAC (DCF + PCF) • Most of 802.11e Implementation (Draft 5.0) • New Frame Format • EDCA • EDCA TXOP Bursting • Polled TXOP Request • Polled TXOP Bursting • No ACK Policy • DLP Javier del Prado et al. Philips

  12. Throughput vs. Frame Size • Simulation Scenario: • There are two senders and two receivers • The senders generate at an infinite rate, L-byte long data frames • The frames are not fragmented • The channel is error free • The beacon interval is 100 ms • The underlying PHY layer is 802.11a • The Data transmission rate is 54 Mb/s • The ACK transmission rate is 24 Mb/s • In EDCA simulations AC_VO parameters are used • For HCCA • The Simple Scheduler defined in 802.11e D5.0 is used • CFP is 90 ms • During CP, wireless STAs use AC_VO • Five frames can be transmitted within a TXOP. Javier del Prado et al. Philips

  13. Throughput vs. Frame Size Javier del Prado et al. Philips

  14. Throughput vs. Number of STAs • 6 different homogeneous scenarios • All stations in each scenario run the same MAC protocol, with same access parameters • Load • Each STA generates 4 Mb/s of traffic • Packet size of 1500 bytes • EDCA • AC default parameters • HCCA • Simple scheduler with TXOPs of 5 ms Javier del Prado et al. Philips

  15. Throughput vs. Number of STAs Javier del Prado et al. Philips

  16. Simulation Results for Usage Scenario 1 Reference: 11-03-802 Javier del Prado et al. Philips

  17. Traffic Generation • As defined in 11-03-802-01 • With the Application parameters as shown in the Applications table • Added VoD control channel for STA4 • STA11 is not simulated – Video Gaming Controller • 0.5 Mb/s with 50 bytes packets?  1250 packets/sec? • Delay Limit of 4 ms? Javier del Prado et al. Philips

  18. Application Set-Up Javier del Prado et al. Philips

  19. TCP Parameters Javier del Prado et al. Philips

  20. TCP Parameters Javier del Prado et al. Philips

  21. WLAN Parameters Javier del Prado et al. Philips

  22. EDCA Parameters • Default Parameters defined in 802.11e D5.0 We have not tried to optimize EDCA Javier del Prado et al. Philips

  23. HCCA Parameters • Used the Simple Scheduler in 802.11e D5.0 • Polling Interval of 30 ms • Minimum Delay Limit of all applications in Scenario 1 We have not tried to optimize Scheduling Algorithm Javier del Prado et al. Philips

  24. PHY Layer • 802.11a frame format and IFSs • Error free channel • All STAs transmit data at 216 Mb/s • Control and Management Frames at 24 Mb/s Javier del Prado et al. Philips

  25. Javier del Prado et al. Philips

  26. DCF Simulation Results • Data is only dropped at the AP • The AP has the same priority than other STAs • Same probability to access the medium • But the AP carries about 50 Mb/s Wireless LAN data dropped Javier del Prado et al. Philips

  27. EDCA simulation results Wireless LAN Throughput Wireless LAN Data Dropped Need to calculate PLR from these results + delay curves Javier del Prado et al. Philips

  28. EDCA simulation results SDTV/HDTV End-to-End Delay Javier del Prado et al. Philips

  29. EDCA simulation results VoIP End-to-End Delay UPLINK Javier del Prado et al. Philips

  30. EDCA simulation results VoIP End-to-End Delay DOWNLINK Javier del Prado et al. Philips

  31. EDCA simulation results TCP Throughput Javier del Prado et al. Philips

  32. HCCA simulation results Wireless LAN Throughput Wireless LAN Data Dropped Most of data dropped is TCP traffic Javier del Prado et al. Philips

  33. HCCA simulation results HDTV/SDTV End to End Delay CDF of HDTV/SDTV End to End Delay Javier del Prado et al. Philips

  34. HCCA simulation results VoIP End-to-End Delay UPLINK Javier del Prado et al. Philips

  35. HCCA simulation results TCP Throughput Javier del Prado et al. Philips

  36. Conclusions • Evaluation of the IEEE 802.11e MAC Throughput as a function of frame size and number of stations • IEEE 802.11e MAC can achieve high efficiency for large frame sizes • Up to 90% • Between 55 and 80% for a 1500 bytes long frame • HCCA throughput is independent of number of Stations Javier del Prado et al. Philips

  37. Conclusions • Simulation of Usage Scenario I • Both EDCA and HCCA guarantee the required PLR in this simulation scenario • There is some data dropped, but given low delay achieved, we can play with the buffer sizes • For a 216 Mb/s PHY rate, the network is close to its limit • We need to include Channel Errors • Do we need to relax the Usage Scenarios definition? • Specially for applications with small packet sizes and low delay limit Javier del Prado et al. Philips

  38. References [1] Sunghyun Choi, Javier del Prado, Stefan Mangold, and Sai Shankar, “IEEE 802.11e Contention-Based Channel Access (EDCF) Performance Evaluation,” in Proc. IEEE ICC’03, Anchorage, Alaska, USA, May 2003 [2] Javier del Prado, Sunghyun Choi and Sai Shankar "IEEE 802.11e EDCF: a QoS Solution for WLAN"  2nd New York Metro Area Networking Workshop, 2002 [3] Javier del Prado and Sunghyun Choi, “Link Adaptation Strategy for IEEE 802.11 WLAN via Received Signal Strength Measurement,” in Proc. IEEE ICC’03, Anchorage, Alaska, USA, May 2003. [4] S. Mangold, G. Hiertz, B. Walke, “IEEE 802.11e Wireless LAN - Resource Sharing with Contention Based Medium Access,” in PIMRC 2003 [5] S. Mangold, “Analysis of IEEE 802.11e and Application of Game Models for Support of Quality-of-Service in Coexisting Wireless NetworksPhD Thesis,” June 2003 [6] S. Mangold, S. Choi, G. Hiertz, O. Klein, B. Walke, “Analysis of IEEE 802.11e for QoS Support in Wireless LANs,” Communications Magazine, Dec 2003 [7] S. Mangold, S. Choi, P. May, O. Klein, G. Hiertz, L. Stibor “IEEE 802.11e Wireless LAN for Quality of Service,” European Wireless 2002 Javier del Prado et al. Philips

  39. Backup Slides Javier del Prado et al. Philips

  40. Where are the overheads coming from? • For a 100 bytes packet and 11a PHY Javier del Prado et al. Philips

  41. Where are the overheads coming from? • For a 100 bytes packet and 11a PHY Javier del Prado et al. Philips

  42. Where are the overheads coming from? • For a 1500 bytes packet and 11a PHY Javier del Prado et al. Philips

  43. Where are the overheads coming from? • For a 100 bytes packet and “11n” PHY at 216 Mb/s Javier del Prado et al. Philips

  44. Where are the overheads coming from? • For a 1500 bytes packet and “11n” PHY at 216 Mb/s Javier del Prado et al. Philips

  45. Where are the overheads coming from? • For a 1500 bytes packet and “11n” PHY at 216 Mb/s Javier del Prado et al. Philips

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