Directional Double Metric Routing in Wireless Mesh Network

Due to unstable link states, broadcasting transmission pattern, and interference between neighbor nodes, routing in wireless mesh network (WMN) is much more complicated and unpredictable than wired network. As the simplest and most primitive routing metric, hop count does not always work well in WMN where routing with least hop count does not bring the best performance. Recent research shows that radio metrics, such as ETX, ETT, etc., work better in routing in wireless mesh network than hop count. These metrics reflect more accurately the link conditions in a mesh network in terms of delay, loss, bandwidth, and so on. However, to our best knowledge one thing, the asymmetry in a wireless link has been neglected the routing protocols developed so far. We propose a double metric routing method with a cross-layer design taking the asymmetry of a wireless link into account, in which monitoring and measurement functions provide metrics in both forward and reverse directions and captures the link state between the node and each of its neighbors. Applying this method to AODV, directional double metric AODV is proposed. By one single route discovering operation the proposed AODV-DDM finds two different paths based on the radio metrics in the forward and reverse directions, from source to destination and from destination to source respectively. Applications with asymmetrical traffic between source and destination are expected to benefit much from the results of this research.