Network Condition-Aware Enhanced Distributed Channel Access for IEEE 802.11e Wireless Ad-Hoc Networks

The increasing use of multimedia applications in wireless ad-hoc networks makes the support of quality of service (QoS) an overriding necessity. In this article, we present a new extension of the IEEE 802.11e EDCA scheme called NCA-EDCA, which uses the lifetime and the number of retransmissions attempts of a packet to assess the aggressiveness of the environment in order to adjust the channel access parameters to work in the best possible way and improve service quality accordingly. This new extension aims to (1) improve the performance of real-time applications; (2) increase the overall throughput by reducing the collision rate and (3) achieve an acceptable level of fairness. The simulation results show that our extension significantly improves EDCA for better QoS support of multimedia applications. More specifically, it increases throughput of the different flows by no negligible factors and significantly reduces the collision rate while maintaining a high degree of fairness between flows of equal priority.