Delay optimization in multi-hop wireless networks with network coding

Network coding (NC) has been shown to improve the throughput of multi-hop wireless networks (MWN). Prior work on performance modeling of NC mainly addresses the maximization of throughput. However, these works fail to capture the complete picture since there may be paths in the network for which end-to-end packet delay is prohibitively high. In this paper, we address the problem of delay minimization in MWNs with NC. The objective has been assignment of wireless node capacities in a way that the average packet delay is minimized for a given network topology and the traffic demand matrix. We develop a performance analysis of the system, which models network nodes as M/G/1 queues and takes into account wireless interference. The proposed model is valid both with and without opportunistic listening for any wireless network topology. The model also incorporates network coding-aware routing that routes the flows in a manner that increases coding opportunities. We present numerical results, which show that NC reduces the average packet delay in the network and extends the stable operating region of the network. We also present simulation results, which confirm the accuracy of the analysis.