Performance Analysis of Auto-shorten DSR-based routing Algorithms in Ad hoc networks

• Main Authors: Chia-ho Cheng, 鄭家和
• Other Authors: Steen J. Hsu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/73506363162154426594

碩士 === 義守大學 === 資訊工程學系碩士班 === 93 === The characteristics of dynamic topology and limited bandwidth make routing algorithms have a great influence on the performance of ad hoc wireless networks. Dynamic Source Routing (DSR) protocol is an on-demand routing protocol based on the concept of source routing. DSR starts a route discovery mechanism when a node needs a route to transmit data. The route discovery mechanism finds a suitable transmission route. After finishing the discovery mechanism, the transmitting path would not be changed except the route is broken. If the network topology has changed and a new shorter path between the source and the destination exists, the source cannot get any information about that and still uses the longer path to transmit data. It wastes the bandwidth of networks. To overcome this problem, two auto-shorten mechanisms have been proposed. In the first one, only the nodes those are in the transmitting path could participate the auto-shorten mechanism. In the second one, all nodes in the networks can participate. Up to date, no literature analyzes the performance of these two auto-shorten mechanisms. The goals of this thesis are` two folds. First of all, the thesis analyzes the performance of these two auto-shorten mechanisms in terms of average hops, average latency, successful delivered ratio, and control overhead, via NS2 simulation system. It was amazing that the performance of the second one isn’t better than the first one. From the simulation results, we found that the life time of the routing information in a node’s cache is too long. It causes the shorten-path may not exist. As a result, the performance cannot to be promoted. Therefore, the second goal of this thesis is to propose a new auto-shorten mechanism to overcome this problem by reducing the life time of the routing information in a node’s cache. Simulation results shows that a appropriate life time can reduce the average hops, average packet delay and makes the performance of the networks to be promoted.