Experimental Evaluation of Medium Access Schemes in 802.11 Wireless Networks

Problem statement: Deployment of real time services over 802.11 wireless networks requires quality of service (QoS) differentiation mechanisms for different traffic types. This required investigations into the performance of the Medium access (MAC) schemes like Distributed Coordinated Function (DCF) and Enhanced DCF with respect to the stringent QoS requirements imposed by the real time services. Motivation for this research was to find the suitability of 802.11 MAC schemes for real time traffic. Approach: In this study, various available MAC schemes were experimentally evaluated for QoS provisioning in 802.11 wireless networks. Performance evaluation was done based on important QoS metrics like access delay, jitter, packet loss, Round Trip Time (RTT) and throughput of the traffic. Experimental Testbed based was established using off the shelf hardware and open source software. The traffic was captured in real time and analyzed thereafter for various QoS metrics. Results: The results indicated that there is considerable QoS improvement using 802.11e EDCF with reconfigured queues over the ordinary DCF mechanism. Results were obtained on experimental testbed using various types of UDP and TCP traffic. Conclusion: It can be concluded that proper differentiation and scheduling of traffic specific to application, helps in providing better QoS over the 802.11 wireless networks and improves their suitability for deployment of real time services.