Routing with opportunistically coded exchanges in wireless mesh networks

Network coding is known to improve network throughput by mixing information from different flows and conveying more information in each transmission. Recently there have been some proposals for applying network coding to wireless mesh networks leveraging the broadcast nature of wireless transmissions. These approaches exploit coding opportunities passively while forwarding packets but they do not proactively change routing of flows to create more coding opportunities. In this paper, we attempt to investigate the extent of performance gain possible when routing decisions are made with the awareness of coding. We first define the expected number of coded transmissions for a successful exchange of packets between two nodes through an intermediate node. We then formulate optimal routing with coding, given the topology and traffic, as a linear programming problem. We conduct a preliminary evaluation of coding-aware routing and show that it offers significant gain particularly when there are many long distance flows.