Rate adaptive MAC protocol for wireless ad hoc networks

The rapid growth of IEEE 802.11 WLANs in recent years has added new dimensions to different MAC layer issues of wireless ad hoc networks. The role of rate adaptation is inevitable in wireless networks since it affects the overall performance significantly. The existing rate adaptation algorithms perform poorly in congested networks since they tend to decrease the transmission rate in high congestion scenario which results in lower throughput and overall performance degradation. A lack of proper identification of congestion measurement technique is one of the main causes of this problem. In this paper, we propose a rate adaptation scheme that employs a lightweight metric known as Channel Busy Time that can differentiate high congestion from low congestion and react according to channel quality variations. We also limit the use of RTS/CTS mechanism in high congestion scenario and show that our proposed scheme, explicitly designed to handle congestion in wireless networks, performs better than the existing rate adaptive algorithms.