Local Repair Mechanisms for On-Demand Routing in Mobile Ad Hoc Networks

With the dynamic and mobile nature of ad hoc wireless networks, links may fail due to topological changes caused by mobile nodes. As the degree of mobility increases, the wireless network would suffer more link errors. Ad hoc routing protocols that use broadcast to discover routes may become inefficient due to frequent failures of intermediate connections in an end-to-end communication. When an intermediate link breaks, it is beneficial to discover a new route locally without resorting to an end-to-end route discovery. Based on the concept of localizing the route request query, we proposed an efficient approach to repair error links quickly. The approach could apply to the Ad hoc On-demand Distance Vector (AODV) routing protocol. As an enhancement to AODV, the proposed approach led to two routing protocols, called AODV-LRQ and AODV-LRT, which were aimed at efficiently repairing the link errors. To evaluate the effects of the route repair, we defined a factor, called bonus gain, as the ratio between the throughput increment to the routing overhead increment. Simulation results show that the proposed methods could get high bonus gain, that was, it could maintain the throughput as well as reduce the routing overheads.Contents 1 Introduction 1 2 Related Work 5 3 Problem Statement 11 4 Route Repair 15 4.1 Repair Quota . . . . . . . . . . . . . . . . . . . . . 16 4.2 Adaptive TTL . . . . . . . . . . . . . . . . . . . . . 19 5 Experiment 21 5.1 Simulation Model . . . . . . . . . . . . . . . . . . . 21 5.2 Parameters and Metrics . . . . . . . . . . . . . . . . 22 5.3 Overview Evaluation . . . . . . . . . . . . . . . . . .23 5.4 Detailed Evaluation . . . . . . . . . . . . . . . . . .24 5.5 Varied Scenario . . . . . . . . . . . . . . . . . . . .29 6 Conclusions 4