Based On NRR And DP Back Route Algorithm

Ad Hoc network is a self-organizing wireless network formed by mobile nodes. And it has a wide range of application in the military and civilian field. AODV protocol is a very classic on-demand routing protocol in Ad Hoc network. And its distinguishing feature is that only when needed, route request begin, reducing the memory requirements. But it exits a fatal shortcoming,that is ,when the valid route fail, the probability of the new established route occuring secondary chain scission is large. Researching how to improve and design a new algorithm about this problem is very valuable and necessary.This dissertation refers to the concept of neighbour residual rate NRR and the dual-path algorithm DP, and they both are combined and used in the local repairing process when the chain scission occurs. On the basis a new improved route algorithm called AODV_NRR_DP is put forward, and it is a back-route algorithm based on NRR and dual paths. When the route chain scission occurs, only the intermediate nodes whose NNR value is greater than the threshold value again begin route request or reply RREP in the neighborhood of chain scission. This avoids secondary chain scission when the node with high mobility or the node whose move method is inconsistent with its neighbour is used to set up valid route. Meanwhile, through the calculation and comparation of NRR value, two nodes whose NRR values are largest are selected to set up two different valid route. When one fail in use, another backup route immediately become valid to put into use, which further effectively improve the valid routing stability in the network. In addition, the improved algorithm has many advantages, such as a higher data packet delivery ratio, lower routing overhead, and smaller average end-to-end delay.In this dissertation OPNET is used to simulate the improved AODV_NRR_DP algorithm. As is shown by the simulation result, this algorithm does better in previous three aspects than AODV_NRR.