ABSTRACT
IEEE 802.11-based wireless local area networks (WLANs) have been widely deployed around the globe due to their low cost, robustness, and ease of deployment. This chapter focuses on the adaptive issues mainly related to the medium access control (MAC) layer in 802.11 WLANs. Adaptive tuning of MAC parameters, such as the contention window (CW) size and carrier sensing range, adaptive scheduling, and cross layer design schemes are shown to improve the MAC performance. The chapter introduces some of the analytical models that strive to accurately describe the dynamic process of the distributed coordination function (DCF). It also introduces some of the existing analytical models for enhanced distributed channel access (EDCA) and several adaptive EDCA schemes. The chapter studies the frame aggregation techniques and introduces an optimal frame size adaptation algorithm. The throughput performance of the optimal frame size adaptation algorithm is compared with a fixed frame aggregation model and a randomized frame aggregation model.
