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

Wireless Local Area Networks IEEE 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

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

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

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 PHY layer  Propagation model  IEEE MAC layer

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

Testbed vs Simulation Throughput - II

Collision Probability - III NodesSimulated collision probability Simulated average backoff Analytical average backoff * H.L. Vu and T Sakurai, “Collision probability in saturated IEEE networks”, ATNAC Australian Telecommunication Networks and Applications Conference 2006T Sakurai *

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

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

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

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

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)

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%

Packet Delivery Ratio (PDR)

Delay

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

The End Questions? Thank You!