Research On Multipath Routing Algorithm For Ad Hoc Networks

Ad Hoc network is self-organized self-reconstructable multi-hop network formed by a collection of wireless mobile nodes without required intervention of any existing infrastructure. In such network, topology, channel circumstances and service mode are rapidly changing with the mobility of nodes. Ad Hoc network has large number of nodes, limited energy and poor computation ability, deficient communication ability and limited bandwidth resource.There are many question still need to be solved in Ad Hoc networks. How to design the routing algorithm suitable for Ad Hoc has become a hot issue recently. Multipath routing protocol can balance data loading and prolong network lifetime. Also, it can take full advantage of topology information to reduce routing cost and deliver data package in parallel via more than one path in routing process. Therefore, based on single path routing algorithms, many multipath routing algorithms have been propoised.In this thesis, we give a detailed introduction to Ad Hoc network's multipath routing algorithms proposed by now, and analyze the actuality and shortcomings of existing work. Based on this, we summarize the specialties of Ad Hoc network's multipath routing algorithms and with the purpose of balancing energy cost and prolonging network lifetime, we propose a n-Divide Multipath Dynamic Source Routing (n-DMDSR) algorithm.The n-DMDSR algorithm references DSR algorithm's route discovery method, source node and midway nods floods RREQ package to all their neighborhood nodes. However, the structure of RREQ and RREP pakage, method to deal with RREQ and RREP as well as the policy of Routing Strategy are different. New algorithm dose not aim at fingding the shortest path or many other paths, instead, it tries to find out less than n's next hop of each midway nodes on the path from the source node to the destination node. Accordingly, in routing process, the source node and each midway node deliver data package to their less than n's next hop nodes in route table.In routing strategy design, n-DMDSR alghorithm takes routing hop countes, the residual energy of nodes and congestion condition of route into consideration, introduces path delay factor, node energy factor and path estimate factor to find more efficient paths.At last, we simulate the n-DMDSR algorithm by OMNET++ simulator and lucubrate the analysis of the results. The simulation results indicate that this algorithm can balance loading among all nodes and prolong the lifetime of the whole network.