Performance evaluation of mobile ad-hoc networks with prioritized messages

Abstract

In a mobile ad-hoc network(MANET), mobile nodes can establish peer-to-peer communications without using a central coordinator. Nodes of MANETs use the distributed coordination function(DCF) of the IEEE 802.11 standard to exchange messages directly between each other. The DCF is a primary random access mechanism based on the CSMA/CA protocol. It enables fast installation with minimal management and maintenance costs and is a very robust protocol for the best effort service in wireless medium. The current DCF, however, is known to be unsuitable for real-time applications such as voice message transmission. In this paper, we focus on the performance issues of IEEE 802.11 which accommodates the prioritized messages. Existing results use the initial window size and backoff window-increasing factor as tools to handle the priority of the messages. Instead, we introduce a novel scheme which chooses the backoff timer with arbitrary probabilities. By this, one can greatly reduce the backoff delay of the lower priority messages without degrading the performance of higher priority.