CSMA/CA MAC Protocol Design for Topology Controlled Ad Hoc Networks: A Cross Layer Approach

Most topology control algorithms proposed so far are mainly for the power savings with the variable transmission powers taking no account of the effect from the underlying MAC protocol. When topology control is adopted in wireless ad-hoc networks with the fact that each node can vary its transmission power, there arise several issues, including throughput degradation, hidden node problem, and fairness problem, that affect the underlying MAC protocol design. In this paper, we investigate these issues when topology control is employed in wireless ad-hoc networks. We show that the throughput performance of MAC protocol is severely degraded when RTS-CTS is transmitted with maximum power. Also, the hidden node problem becomes very significant if RTS-CTS range is reduced improperly. We propose an algorithm to set up RTS-CTS range that can alleviate the hidden node problem, avoid the degradation of the throughput performance of MAC protocol, and resolve the fairness problem.