Research On Reliable Routing In Wireless Ad Hoc Network

The wireless ad hoc networks have been received more and more attention in recent years. Many routing protocols have been proposed for ad hoc network.The dynamic source routing (DSR) protocol proposed by Carnegie Mellon University has relatively better performance.The dynamic source routing (DSR) was improved by our lab.The modified DSR was named QDSR. We cancel the retransmission of packets , add the QoS mechanisms ,add the dynamic ack mechanism,add the backup routing mechanism. QDSR achieved satisfying performance during a series of experiments outdoors.Although, QDSR can performs well when the numer of nodes in network is few and hop number of path is no more than 3. But, because of constraint of available devices and other conditions, the number of nodes in the experiments outdoors is limited to at ten at most. To validate the effectness of QDSR in relatively large networks, the author and other peoples in our laboratory have implemented QDSR via NS2, which can improve the performance of QDSR for the scenes with many nodes.This paper presents a reliable routing protocol in QDSR .First, ETX(Expected Transmission Count)mechanism, which can ignore the bad link in routing path, is added to QDSR for finding a reliable routing. Second, this paper presents a new backup routing mechanism, instead of the backup routing mechanism of QDSR, so that route recovering can be initiated from middle nodes on the broken path and, therefore, the route recovery can be done fast.After numerous simulation experiments and analysis of siomulation result, compared with original QDSR, the modifications made in this paper are effective, the performance of QDSR is improved.