Development and performance characterization of enhanced AODV routing for CBR and TCP traffic

Abstract

We aim to modify an existing mobile ad-hoc network (MANET) reactive routing protocol (ad-hoc on-demand distance vector, AODV) into a hybrid protocol by introducing adaptive, proactive behavior to improve its performance. Under our proposed scheme, route maintenance decisions are based on predicted values of 'link-breakage times' (when the next-hop node will move out of transmission range) obtained from a series of position/speed estimates of the next-hop node. These estimates are based on the power level of the received MAC frames. If a link is about to break, proactive discovery of new routes to all destinations using the next-hop node depends on the history of traffic to that destination. We simulated (using the ns2 simulator) numerous test conditions using CBR and TCP traffic and compared performance metrics for the original and modified versions of the protocol. We have achieved (1) a significant reduction in mean packet latency for CBR traffic and (2) a reduction in control overhead in TCP traffic, while incurring other small penalties for both types of traffic. Also, a comparison of some performance metrics for TCP and CBR traffic leads us to conclude that slight modifications in TCP can lead to its improved performance over MANETs.