Efficient broadcasting in ad hoc wireless networks using directional antennas

Using directional antennas to conserve bandwidth and energy consumption in ad hoc wire-less networks (or simply 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 wireless networks using directional antennas. DSP is a non-trivial generalization of an existing localized deterministic broadcast protocol using omnidirectional antennas. Compared with its omnidirectional prede-cessor, 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 bandwidth- and energy-efficient. DSP is based on 2-hop neighborhood information and does not rely on location or angle-of-arrival (AoA) information. Two special cases of DSP are discussed: the first one preserves shortest paths in reactive routing discoveries; the second one uses the directional reception mode to minimize broadcast redundancy. DSP is a localized protocol. Its expected number of forward nodes is O(1) times the optimal value. An extensive simulation study using both custom and ns2 simulators shows that DSP outperforms significantly both omnidirectional broadcast protocols and existing directional broadcast protocols