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Performance Analysis and Evaluation of WiMedia UWB MAC protocols

Masters Thesis Proposal Rukhsana Ruby University of Victoria. Performance Analysis and Evaluation of WiMedia UWB MAC protocols. History of IPTV. IP/TV – First Internet Video product, 1995 An IPTV over DSL broadband by Kingston Communications, 1999

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Performance Analysis and Evaluation of WiMedia UWB MAC protocols

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  1. Masters Thesis Proposal Rukhsana Ruby University of Victoria Performance Analysis and Evaluation of WiMedia UWB MAC protocols

  2. History of IPTV • IP/TV – First Internet Video product, 1995 • An IPTV over DSL broadband by Kingston Communications, 1999 • IPTV service by AT&T, 2006 – 300 channels in 11 cities • Nowadays Broadband connections are widespread • Served more than 200 million households, 2005 • Will grow to 400 million by 2010

  3. IPTV in-home distribution • Ethernet solution – Rewiring is expensive and awkward • No new-wires solution – availability and achievable performance is uncertain • Wireless solution

  4. Outline • Existing WLAN/WPAN Technologies • UWB Overview • Summary of UWB Experimentation • Methodology • Performance Results • Discussion of limitations of current work • Future Research

  5. Existing WLAN Technologies • Support low data rate (11 to 54 Mbps)‏ • 802.11b and 802.11a/g (Achieve less than 50% of actual data rate)‏ • Work in 2.4 and 5 Ghz frequency band. • avg throughput of 802.11g 10 Mbps • Contention – based MAC • 802.15 family supports maximum 55 Mbps data rate in very short range (10 metre)‏

  6. UWB Overview • UWB is a radio technology • UWB is regarded as the best technology for the high-speed wireless PAN. Why? • High speed at short range • Up to 480Mb/s currently. Ultimately support the speed at Gbit/s. • In the range of 10 meters. • Radio spectrum: 3.1 to 10.6 GHz (very large). • Low energy consumption level

  7. UWB MAC • Time is divided into super frames. • 256 MAS (Each MAS is 256us)‏ • Beacon Period (First 32 MAS)‏ • Contract and Expand able • Data Period • DRP and PCA (Like 802.11e)‏ • Acknowledgement Policy • No, Block and Immediate Acknowledgement

  8. Overview of EDCAF • User traffic is differentiated • Minimum contention window size • Retry limit • Arbitration inter-frame space • TXOP limit • Backoff counter is decremented ahead of slot time no matter slot is busy or idle • User traffic is denoted by ACi {i = 1, 2, 3,4}

  9. Discussion (UWB Experimentation)‏ • Tradeoff between TxRate and Retry Limit • Throughput, Latency tradeoff between clustered and scattered reservation. Fig. Throughput vs. Reservation Pattern Fig. Goodput vs. TxRate and Retry Limit

  10. Renewal Reward Theorem Other station’s transmission Tagged station’s transmission

  11. EDCAF Analysis C S C Fig: Illustration of renewal cycle Frame service time = (E[R] + E[B])*generic slot

  12. EDCAF Analysis(Cont.)‏ Expected number of retransmissions Expected number of backoff slots Transmission probability Collision probability of AC2 station Collision probability of AC1 station

  13. EDCAF Analysis(Cont.)‏ Generic slot calculation Frame service time for AC1 station

  14. EDCA Analysis (Cont.)‏ • Frame service time for low priority station are two parts • Number of generic slots in zone 2 • Pre-backoff waiting period First part of frame service time for AC2 station Each pre-backoff waiting period length Total pre-backoff waiting period Frame service time for AC2 station

  15. EDCAF Analysis (With DRP)‏ No. of DRP faced by AC1 station Frame service time for AC1 station Frame service time for AC2 station TQ is the summation of DATA tx time, ACK tx time, SIFS and guard time

  16. Simulation Methodology • Simulator – ns-2 • Modified TKN implementation of 802.11e • 802.11 physical layer to UWB • Incorporate super frame structure • Insert some hard drp in super frame

  17. Simulation Scenario AC2 station AC1 station Radius of circle: 20 metre Tx range: 250 metre Freespace propagation model Data rate: 480 Mbps MAC layer Packet size with all overhead: 1500 bytes Min contention window for AC1: 7 Min contention window for AC2: 15 Retry limit: 7 AIFS1: 2 slots AIFS2: 4 slots Base station

  18. Saturated Simulation and Analysis Results (Without and with DRP)‏ Beacon period: 1-32 DRP: 100-132, 200-232 Fig. Frame service time with DRP Fig. Frame service time without DRP

  19. Unsaturated Analysis Collision Prob of AC2 station Collision Prob of AC1 station Prob of no AC1 station transmits in zone 1 Pre-backoff waiting period per backoff segment for AC2

  20. Unsaturated Simulation and Analysis Results (Without DRP)‏ Offered Load: 0.00086 frames/slot Number of stations: 10 Fig. Frame service time without DRP Fig. Frame service time without DRP

  21. Discussion • Difficult to get the exact pre-backoff waiting period for AC2 station. • Due to propagation delay perfect simulation result is not possible. • Frame service time in the presence of DRP is also approximation.

  22. Future Research • Extend the model to allow heterogeneous traffic. • Send video over UWB, find performance metrics and improvement scope. • Distributed algorithm for DRP allocation

  23. Thank You! Questions?

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