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!