A Comparative Study of Dynamic Adaptation Algorithms for Enhanced Service Differentiation in IEEE 802.11 Wireless Ad Hoc Networks

EDCA is a contention-based channel access scheme defined in the IEEE 802.11e standard, and is part of HCCA for infrastructure networks, however it may be used as a separate coordination function for wireless ad-hoc networks. In this paper, we present two main schemes that extend EDCA with a dynamic adaptation algorithm enabling each station to tune the size of the CWmin used in its back-off algorithm at run time. The performance of the IEEE 802.11e EDCA, enhanced with our adaptation algorithms, is extensively investigated by simulations and compared with other contention window adaptation schemes, such as, Adaptive EDCF (AEDCF), and Slow Decrease (SD) schemes. Results obtained indicate that our CWmin adaptation schemes outperform basic EDCA, AEDCF and SD in terms of channel utilization, throughput, and packet delay. We show through simulations that the delays for high priority and medium priority access categories decrease by up to 63% and up to 96% respectively. We also show that the total throughput increases by up to 24%, and channel capacity is at least 30% higher as compared to EDCA.