Many MAC sub-layer protocols for supporting the usage of directional antennae in ad hoc networks, have been proposed in literature. However, there remain two open issues that are yet to be resolved completely. First, in order to fully exploit the spatial diversity gains due to the use of directional antennae, it is essential to shift to the exclusive usage of directional antennae for the transmission and reception of all the upper layers frames. This would facilitate maximal spatial re-use and will efface the phenomena of asymmetry in gain. Second in the presence of mobility the MAC protocol should incorporate mechanisms by which a node can efficiently locate and track its neighbors.

In this paper we propose a new polling based MAC protocol that addresses both the issues in an integrated way. We perform analysis and extensive simulations to understand the performance of our scheme in terms of its ability to maintain connectivity, the achieved utilization efficiency, and throughput. We find that each node, on average, can achieve a per node utilization of about 80% in static and about 45% in mobile scenarios. Our protocol is seen to outperform both the traditional IEEE 802.11 MAC protocol and previosuly proposed protocols for use with directional antennae that provide partial solutions to solve the afore-mentioned problems. Finally, we also study the sensitivity of our protocol to various system parameters.