Multibeam antenna scheduling in ad hoc wireless networks

Directional antennas have shown to be advantageous in an ad hoc wireless network over traditional omnidirectional antennas to provide higher network throughput because they can reduce the power required for the service coverage and packet transmission, mitigate interference in the directions away from that of the desired users, and reduce the number of hops between distant source and sink nodes. Recently, multibeam antennas (MBAs) have been developed to further increase the network throughput. MBAs can be implemented using either multiple fixed-beam directional antennas or multi-channel smart antennas. The difference between them lies in whether the beams are predefined or adaptively controlled. MBAs not only inherit the advantages of directional antennas, but also support concurrent communications with multiple neighboring nodes. Such advantages are achieved, however, only with sophisticated scheduling schemes. For example, it is crucial to appropriately allocate the available beams to the neighboring users that attempt to transmit packets. Previous results have shown the importance of utilizing appropriate scheduling in avoiding collision. Specifically, in a multipath propagation environment, signals transmitted from a neighboring node may fall into multiple beams at the receiving node and thus result in more frequent contentions. In this paper, we examine the feasibility and node throughput performance of relevant scheduling algorithms, such as those based on packet priority and throughput maximization, and investigate the effect of multipath propagation on the exploitation of the scheduling schemes as well as on the throughput performance.