Link-quality-based On-demand Routing Protocol Research For Wireless Ad Hoc Network

Wireless ad hoc network routing protocol is an important part of wireless ad hoc network, it largely determines the characteristics and performance of wireless ad hoc network. In recent years, due to the widely used wireless ad hoc networks, its routing protocol has also considerable development. However, there are a lot of traditional wireless ad hoc network routing protocols evolved from the wired network routing protocols, which still contains some shortages that are not suitable for wireless ad hoc network. This thesis studies the problems of traditional routing protocols and its essential reasons. To solve these problems, this thesis proceeds in two ways, on the one hand, the precise multi-parameter link quality estimation method is studied by this thesis; on the other hand, the link-quality-based route discovery algorithm and the link-quality-based route maintenance algorithm is studied by this thesis.In first part, this thesis proposes a new link-quality estimation algorithm, which utilizes the probe messages to estimate the packet loss rate and the link delay simultaneously. Firstly, a packet arrive time model is established; secondly, the thesis proposes a moment-estimation-based link-quality estimation algorithm to get the parameters of the packet arrive time model. And the estimated result is the link packet loss rate and link delay. Finally, a simulation is designed to show the performance of estimation algorithm, and the simulation results prove that the estimator could make a low RMSE link-quality estimation.In second part, this thesis proposes and implementations an optimum link-quality on-demand mobile ad hoc network routing protocol, which includes routing discovery algorithm and routing maintenance algorithm. In the part of routing discovery algorithm, the link-quality is transformed to the routing discover priority to obtain the routing which has the optimum link-quality. In addition, the thesis also designs a routing maintenance algorithm which matches with the routing discovery algorithm. It could detect unstable links timely and guide the routing maintenance operation, thus ensuring the long-term effective routing. This thesis also designed a simulation based on NS2, the simulation studies the impact of network size, node mobility, data transmission rates to packet loss rate, end to end delay, packet routing control overhead and the average number of hops. Simulation results show that the new protocol exhibits better performance than AODV and DSDV in most respects.In order to validate the new routing algorithm practicality in a real environment, the new routing algorithm is implemented on Linux as a real routing protocol. This thesis gives the details of the implementation scheme of the new routing protocol. And then, this thesis conducts a series of experiments under a real environment. Compared with the shortest-hop-routing scheme, the experiment results show that the new protocol exhibits a higher end-to-end transmission speed.