Effects of Loss Rate on Ad Hoc Wireless Routing

Abstract

This paper uses measurements from two deployed wireless ad hoc networks to illustrate the effects of link loss rates on routing protocol performance. Measurements of these networks show that the radio links between the majority of nodes have substantial loss rates. These loss rates are high enough to prevent existing ad hoc routing protocols from using the links. Link-level retransmission can mask high loss rates, at the cost of substantial decreases in throughput. Simulations, driven by the observed loss rates, show that the shortest paths chosen by existing routing protocols tend to find routes with much less capacity than is available along the best route. Based on these observations, we present a routing metric intended to allow routing protocols to find good routes in wireless ad hoc networks. The metric is the expected total number of transmissions required to deliver a packet along a route. This metric favors routes with high throughput and low total impact on spectrum. It is expected to perform better than existing techniques that eliminate links based on loss rate thresholds.