How does randomized beamforming improve the connectivity of ad hoc networks?

This paper analyzes the impact of beamforming antennas on the topological connectivity of multihop wireless networks. As a metric for the connectivity of the network, we use the percentage P(path) of nodes that are connected via a multihop path. We show that simple randomized beamforming - i.e., each node adjusts its main beam into a randomly chosen direction for transmission and reception - significantly improves P(path) compared to networks with omnidirectional antennas employing the same power and sensitivity. The study is performed using accurate, analytical antenna models for uniform linear and circular antenna arrays. Already small arrays with four antenna elements give high gains of P(path). These gains are achieved although the nodes' average number of neighbors does not necessarily increase.