Abstract

This paper describes two techniques that improve through-put in an ad hoc network in the presence of nodes that agree to forward packets but fail to do so. To mitigate this prob-lem, we propose categorizing nodes based upon their dynam-ically measured behavior. We use a watchdog that identifies misbehaving nodes and a patl~rater that helps routing pro-tocols avoid these nodes. Through simulation we evaluate watchdog and pathrater using packet throughput, percent-age of overhead (routing) transmissions, and the accuracy of misbehaving node detection. When used together in a net-work with moderate mobility, the two techniques increase throughput by 17 % in the presence of 40 % misbehaving nodes, while increasing the percentage ofoverhead transmis-sions from the standard routing protocol's 9 % to 17%. Dur-ing extreme mobility, watchdog and pathrater can increase network throughput by 27%, while increasing the overhead transmissions from the standard routing protocol's 12 % to 24%. 1.