On the Performance of Expected Transmission Count (ETX) for Wireless Mesh Networks

The Expected Transmission Count (ETX) metric is an advanced routing metric for finding high-throughput paths in multi-hop wireless networks. However, it has been determined that ETX is not immune to load sensitivity and route oscillations in a single radio environment. Route oscillations refer to the situation where packet transmission switches between two or more routes due to congestion. This has the effect of degrading performance of the network, as the routing protocol may select a non optimal path. In this paper, the authors avoid the route oscillation problem using a route stabilization technique which forces data transmission on a fixed route. They implement this solution in a popular routing protocol, AODV, by disabling both error messages and periodic updating messages.