Directional antenna based time division scheduling in wireless ad hoc networks

Abstract

Conventional omni-antenna ad hoc MAC protocols, such as the IEEE 802.11, use RTS/CTS mechanism to avoid collision but waste much resources by reserving the wireless media over a large area. Using directional antenna is a good solution to increase spatial reuse, however, packet collision caused by hidden nodes and deafness problem are serious. Recently, many schemes based on directional antenna in ad hoc networks have been proposed, however, most of the schemes have not solved the hidden node and deafness problem completely. In our paper, in order to solve these problems, a time division self scheduling based MAC protocol is proposed. We let all the nodes overhear control messages at a fixed period periodically and the control messages exchanging will be done during this fixed period. Based on these control messages exchanging, channels for future data communication can be reserved in advance. Thus, in the data communication period, each data communication uses the successfully reserved channel to transmit data packet that can reduce packet collision significantly. Our proposed scheme can efficiently reduce hidden node problem and the deafness problems, which is a specific problem in directional antenna based network. Through simulation results, we have found that our scheme performs better than conventional protocol in the static ad hoc network with respect to throughput and end to end delay. That is, our proposed scheme provides a good method to solve the hidden nodes, deafness problem and also reduce much interferences to guarantee the successful data transmission in wireless ad hoc networks.