A Rate-Adaptive MAC Protocol for Wireless Networks

Wireless local-area networks are becoming increasingly popular. This is due, in part, to the recent availability of devices capable of communicating at data rates approaching that of conventional wired networks. These high rates are made possible through new modulation and coding techniques that dramatically increase bandwidth efficiency. However, maintaining reliable communication at higher data rates requires more signal power. Consequently, wireless devices often support multiple data rates, providing the user the ability to choose the rate that best suits their application. Alternatively, an automatic rate adaption mechanism may be used. Rate adaption is the process of automatically selecting the rate that gives the optimum throughput for the channel conditions. Although rate adaption mechanisms for cellular wireless networks have been studied at length, few have been proposed for wireless local-area networks. This paper presents one such mechanism: a rate adaptive MAC protocol based on the RTS/CTS collision avoidance handshake, called the Receiver-Based AutoRate (RBAR) protocol. The protocol is unique in that the rate adaption mechanism is located on the receiver, instead of the sender. Simulation results of an implementation of RBAR into IEEE 802.11 show that this arrangement performs well, in comparison to an existing protocol.