Exploiting congestion information in network and higher layer protocols in multihop wireless ad hoc networks

With most routing protocols for ad hoc networks, shorter paths are generally considered more desirable, making some areas of network more prone to congestion and decreasing overall network throughput. We examine the use of congestion information to avoid these network hotspots. By locally monitoring the network interface transmission queue length and MAC layer behavior at each node, a node can establish an approximation of the degree to which the wireless medium around it is busy; this measurement reflects not only the behavior of the node itself, but also the behavior of other nearby nodes sharing the wireless medium. We suggest a number of uses of such congestion information in an ad hoc network, in the network, transport, and higher layers, and we evaluate a set of such uses through simulation. Our results based on modifications to the dynamic source routing protocol (DSR) and TCP demonstrate substantial performance improvement in terms of scalability, packet delivery, overhead, and fairness resulting from this use of congestion information.