Research On The Multi-Path Routing Protocols Of Ad Hoc Network

Wireless mobile Ad hoc networks formed by a collection of mobile nodes through radio links are typically characterized by their multi-hop, temporary and un-center. They can be quickly built up anywhere and anytime, and needn't be supported by basic network devices. In such networks every terminal is equal and can move freely. Considering the moving of nodes in Ad hoc networks and constantly variety of network topology, at the same time, due to the compute-capability of mobile nodes and storage-capacity are low and the energy sources are limited, so the routing protocols have to be simple as best. All those add difficulties to the routing protocol design in Ad hoc networks. So research and design of stable and highly efficient protocols have been very hot issues for current Ad hoc networks.Firstly, this thesis introduces current typical Ad hoc routing protocols, analyzes and compares their performances in sum. Then AODV is described in detail. AODV maintains only one route from a source to its destination, and this condition is likely to result in termediate nodes congestion, thus lowering the overall network throughput and increasing end-to-end transmission delay. In the communication process, routes already built are likely to disconnect for nodes move, need to be rebuilded, which will impact the quality of service greatly. Furthermore, as for some characteristic of AODV, there may have implied routing changes, in other words, the established routes may be changed by other routing process, which will harm the quality of service and traffic engineering algorithm implementation. In order to overcome the above shortcomings of AODV, I have brought forward a node-independent multi-path routing protocol based on AODV--TRND-AODV (Tree Root Node Disjoint Ad hoc On Demand distance Vector).The basic idea of TRND-AODV is to build node-independent routes using the source neighbor nodes. If the reply and local recovery functions of intermediate nodes are both closed, when the source node send RREQ message to the destination node, the route RREQ take will be many node-trees, and the trees' root nodes are some souce neighor nodes. The characteristic of the tree that they have only one root no matter how many branches they have can help us distinguish between the node-independent paths. In addition, we have added source node address domain to the routing table, so a certain routing will be identified in accordance with the source and destination address, thus the implied change problem discussed aboved will be sovled.Many simulation tests have be conducted on OPNET simulation platform, proving many performances of TRND-AODV is superior to that of AODV, especially the network evaluation parameters of packet delivery fraction, end-to-end delay and routing overheads.This thesis is supported by National Natural Science Foundation of China (60372101).