Efficient Broadcasting in Ad Hoc Networks Using Directional Antennas

Using directional antennas to conserve bandwidth and energy consumption in ad hoc networks is becoming popular in recent years. However, applications of directional antennas for broadcasting have been limited. We propose a novel broadcast protocol called directional self-pruning (DSP) for ad hoc networks using directional antennas. DSP is a non-trivial generalization of an existing localized deterministic broadcast protocol using omnidirectional antennas. Compared with its omnidirectional predecessor, DSP uses about the same number of forward nodes to relay the broadcast packet, while the number of forward directions that each forward node uses in transmission is significantly reduced. With the lower broadcast redundancy, DSP is more bandwidthand energy-efficient. DSP is based on 2-hop neighborhood information and does not rely on location or angle-of-arrival (AoA) information. DSP is a pure localized protocol. We prove that the expected number of forward nodes in DSP is within a constant factor of the minimal value in an optimal solution. Our simulation results show that DSP can reduce the transmission cost by 30%–65%.