Optimization of multicast routing for network lifetime with directional listening

Energy and spectrum constrained wireless ad hoc networks must employ efficient forwarding schemes to conserve resources. The incorporation of directional antennas allows for focusing transmitted energy toward a specific node, or increasing reception gain in a specific direction. This provides not only a means to conserve power, but also allows for spatial multiplexing by reducing inter-node interference. In many cases of interest, it is likely that only a subset of nodes in a network will be equipped with directional transmission/reception capabilities. The existing literature on the impact of directional antennas on the lifetime of ad hoc networks does not consider node heterogeneity or model directional listening. In this paper, we develop a Mixed Integer Linear Program to model directional reception. The program's objective is to maximize network lifetime in multicast applications. We consider cases where some (but not all) network nodes are equipped with directional antennas. Our results illustrate the impact of node density and proportion of nodes with directional capabilities on network lifetime.