Opportunistic Routing with Directional Antennas in Wireless Mesh Networks

Opportunistic routing significantly improves the average progress per transmission over unicast routing by leveraging the opportunistic receptions of multiple potential forwarders in wireless mesh networks. Prior studies mainly focus on networks with omni-directional antenna only. Our previous work suggests that not every node contributes equally in a transmission. By concentrating the beam energy at a particular direction, directional antennas may further improve the performance of opportunistic routing in multi-hop wireless networks. In this paper, we derive an analytical model which allows the incorporation of various node distribution models, radio channel models and antenna models to evaluate the average progress per transmission. It is found that a directional antenna with high directivity does not always improve the performance of opportunistic routing and an optimal beamwidth exists for each particular network. When compared to the case of omni-directional antenna, a directional antenna with optimal beamwidth and direction settings can achieve 30 to 50% performance gain, in terms of average progress per transmission, under typical network configurations. Moreover, such performance gain can be as high as 100% for radio propagation environments where the packet reception probabilities fall off slowly with distance.