A robust cross-layer metric for routing protocol in mobile wireless ad hoc networks

In a mobile ad-hoc network (MANET) where Mobile Nodes (MNs) self-organize to ensure the communication over radio links, routing protocols clearly play a significant role. In future MANETs, protocols should provide routing under full mobility, power constraints, fast time-varying channels, and nodes subject to high loading. In this article, a novel robust routing protocol, named distributed X-layer fastest path (DXFP), is proposed. The protocol is based on a cross-layer metric which is robust against the time-variations of the network as far as topology (mobility), congestion of the nodes and channel quality (fading, power constraints) are concerned. All these features are integrated in a single physical cost, i.e., the network crossing time, which has to be minimized. Furthermore, several routes from source to destination are stored for a given data flow to efficiently face the disconnections which frequently occur in MANETs. It is shown that the DXFP protocol, though locally operating in a fully distributed way within the MNs, provides, for each data flow, the optimum routes according to the considered metric. The DXFP protocol has been compared with two of the most commonly used routing protocols for MANETs, i.e., dynamic source routing and ad hoc on-demand distance vector, showing significant improvements in performance and robustness.