Receiver-Oriented Multiple Access in Ad Hoc Networks with Directional Antennas

Directional antennas can adaptively select radio signals of interest in specific directions, while filtering out unwanted interference from other directions. A couple of medium access protocols based on random access schemes have been proposed for networks with directional antennas, using the omnidirectional mode for the transmission or reception of control packets in order to establish directional links. We propose a distributed receiver-oriented multiple access (ROMA) scheduling protocol, capable of utilizing multibeam forming directional antennas in ad hoc networks. Unlike random access schemes that use on-demand handshakes or signal scanning to resolve communication targets, ROMA computes a link activation schedule in each time slot using two-hop topology information. It is shown that significant improvements on network throughput and delay can be achieved by exploiting the multi-beam forming capability of directional antennas in both transmission and reception. The performance of ROMA is studied by simulation, and compared with a well-know static scheduling scheme that is based on global topology information.