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Performance Evaluation of WLAN for Mutual Interaction between Unicast and Multicast Sessions

This thesis assesses WLAN performance through simulations, focusing on unicast and multicast interactions. It examines challenges like QoS requirements and MAC constraints, presenting a novel mobility model for group communication.

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Performance Evaluation of WLAN for Mutual Interaction between Unicast and Multicast Sessions

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  1. Performance Evaluation of WLAN for Mutual Interaction between Unicast and Multicast Communication Session Author: Aamir Mahmood Supervisor: Prof. Riku Jäntti

  2. Wireless Local Area Networks • IEEE802.11 family of standards • Maturity of standard, low cost infrastructure, operation in unlicensed band • Simple standalone infrastructure • Extensions to existing networks (WiMax, TETRA) • Providing access for high speed data and multimedia services • Growing interest in outdoor operation of IEEE802.11

  3. WLAN for Real-Time Services • Primary objective - asynchronous (data) services • Case: A realistic network with multiple wireless technologies complementing each other • Requirement: Support for data and real-time services • Challenges: • Uncontrolled and unreliable propagation environment • Stringent Quality of Service (QoS) requirements • Performance and scalability constraints of MAC algorithm

  4. Thesis Contribution • WLAN evaluation by simulations under mutual interaction of unicast and multicast real-time sessions • Extending the isolating study of unicast and multicast sessions • Evaluation Steps: • Designing a prototype for simulator verification (PHY and MAC parameters, backoff time distribution, collision probability) • Mobility with a proposed model • Optimal size of WLAN cell, suitable for unicast and multicast sessions under TWO-RAY propagation model

  5. Test bed and Simulator • Test environment concerns • Modifications in system parameters • Reliability and reproducibility of the results • Test bed • Open Source Components: operating system, WLAN adaptor drivers, real-time traffic emulation software, traffic monitoring and sniffing • Simulator • Qualnet 4.0 – Reliable and comprehensive modeling / simulation • Signal reception model • IEEE 802.11 PHY layer • Propagation model • IEEE 802.11 MAC layer

  6. Prototype Design for Simulator Verification - I • Maximum aggregate throughput for two nodes with UDP flooding • Constant propagation environment • Measure the collision probability • Two nodes sharing the equal throughput

  7. Testbed vs Simulation Throughput - II @11Mbps @2Mbps

  8. Collision Probability - III * *H.L. Vu and T Sakurai, “Collision probability in saturated IEEE 802.11 networks”, ATNAC Australian Telecommunication Networks and Applications Conference 2006

  9. Group Mobility • The proposed mutual interaction of unicast and multicast sessions is well-suited for simultaneous one-to-one and group communication • The performance for the proposed joint flows is evaluated under a proposed group mobility model • The model maps the mobility of public safety cooperative activities

  10. Proposed Mobility Model • The deployment of users towards a randomly selected hotspot area belonging to the cell • Uniform initial distribution • Speed of the user is proportional to the distance from the destination in the hotspot • The destination location of a user in hotspot is also uniformly distributed

  11. Statistical Analysis - I Rc = 1 units, Ro = 0.1 units, Vmin = 0.005 units/sec Vmax = 0.015 units/sec Velocity as a function of distance between the initial and final position PDF of initial speed distribution

  12. Statistical Analysis - II Instantaneous network speed as a function of the simulation time Spatial distribution of the nodes

  13. Mutual Interaction of Unicast and Multicast Communication Session • Scenario • Single multicast VoIP session in the downlink direction • Increasing number of unicast VoIP session in the uplink direction • Effect of adding one unicast video feed in addition to the uplink VoIPs • Performance measurement • How does the performance of multicast session is degraded and vice versa? • Metrics • Packet Deliver Ratio • PDR • PHY and MAC parameters, traffic emulation • VoIP: CBR G.711 with 10ms payload size (92 bytes/packet) • Video: CBR 30ms payload size (360Kbps)

  14. Simulation Setup • Cell radiuses 2Mbps: Target SNR = 6dB Cell Radius =300m 11Mbps: Target SNR = 10dB Cell Radius =240m • Probability of hidden nodes • Carrier sensing range (534m) • Hidden node probability 3%

  15. Packet Delivery Ratio (PDR)

  16. Delay

  17. Final remarks • The degradation in performance can be concluded as • For multicast session it is the low PDR • For unicast sessions it is the increasing average delay • Future Work • It is expected that the degradation would be severe in the presence of fading • It will be more appropriate to model the traffic instead of considering the CBR type of traffic • DCF vs PCF

  18. The End Questions? Thank You!

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