Study On Reliable Routing In Ad Hoc Networks Based On DSR Protocol

With the development in computer and wireless communication technologies,mobile wireless networks are in increasingly widespread use. The wireless ad hocnetworks have been received more and more attention due to their characters ofhaving no infrastructure. Various routing protocols that are tailored to wireless ad hocnetworks have been put up in recent years by researchers around the world. And therelated analyses of performance of routing protocol are being done from differentaspects. Since nodes in the wireless ad hoc networks move freely and instability ofwireless channel, how to improve the route reliability becomes one of the centralchallenges in such networks.Among wireless ad hoc routing protocols, one named Dynamic Source Routing(DSR) proposed by Carnegie Mellon University is a representative protocol. But DSRcan not provide reliable routing, and the main problem of it is the performancedegradation caused by frequent route broken. To overcome the problem,Route-lifetime Estimation Based Dynamic Source Routing (REBDSR), based on DSR,is proposed in this paper. REBDSR uses several new mechanisms that are based on anestimation of link-lifetime to improve the route reliability. It consists of three modules:link state estimation, improved route discovery and active route maintenance. Thelink state estimation modules can predict the residual-lifetime of a link based onreceive power. During the route discovery, the route-lifetime is equal to the minimumlifetime of the links that construct the route, and the route selection depends on notonly the route hops but also the predicted route-lifetime. During the routemaintenance, REBDSR can take maintenance actions based on the predictedlink-lifetime before the old route is actually broken. Besides, we use new route cachemanagement to alleviate the influence of stale route in DSR.A lot of simulation experiments have been done under NS2. The Simulationresults demonstrate that REBDSR has two interesting features: (1) In the middle-loadand heavy-load situations, REBDSR can improve the performance of DSR protocolsignificantly. (2) In the more challenging situations of high mobility, REBDSR ismore adaptable. We can say REBDSR is an efficient and reliable protocol in wirelessad hoc networks.