Directional Routing for Wireless Mesh Networks: A Performance Evaluation

Routing in multi-hop wireless networks involves the indirection from a persistent name (or ID) to a locator. One of the biggest issues in routing is providing adequate connectivity while scaling the network. Recently, Bow-Nan Cheng et al., (2006) has attempted to mitigate this issue by using directional communication methods to find intersections between source-rendezvous and rendezvous-destination paths, providing effective routing in unstructured, flat networks. Cheng et al. showed that by "drawing" two lines orthogonal to each other at each node, it is possible to provide over 98% connectivity while maintaining only order O(N^3/2) states. It is interesting, however to investigate what happens when additional lines are "drawn" and how that affects connectivity, path length and state complexity. In this paper, we examine how transmitting along one, two, three, and four lines affects routing and provide both analytical bounds for connectivity as well as packetized simulations on how these methods stack up in a more realistic environment. We show that by sending packets out in more directions, increased connectivity and smaller average path length results only up to a point. The trade-off, however, is added state information maintained at each node. We also show that in mobile environments, adding additional lines increases the chances for successful packet delivery only marginally.