Design And Implementation Of A Table-driven Routing Protocol In Hierarchical Ad Hoc Networks

A wireless ad hoc network is a kind of distributed multi-hop network consisting of a set of nodes with the function of routing,and it does not need any default network infrastructures.With the rapid development of ad hoc network,reducing the control overhead of traditional routing protocols has become a difficult problem.Moreover,the expansion of network size leads to an increase in the convergence time of the routing protocol,coupled with the mobility of nodes,which will keep the accuracy of the entire network routing information difficultly.Therefore,it is very important to study the routing protocol which is suitable for large-scale networks and has low overhead and fast convergence in ad hoc network.Based on the PV(Path Vector)routing algorithm,a routing protocol,which is suitable for large-scale networks,reduces control overhead and improve the convergence speed,is proposed,called LDPV(Layered Double Path Vector).In the LDPV,each node periodically broadcasts intra-network routing packets and maintains an intra-network routing table reaching other nodes within the subnet.The gateway of each subnet periodically broadcasts inter-network routing packets,maintains an inter-network routing table reaching other subnets,and uses routing packets of the backbone-network to notify the other nodes in the subnet the corresponding subnet gateway node which reaching the destination subnet.In order to adapt to the frequent changes in the network topology,LDPV protocol uses a double-path routing,in which the two different routing entries are recorded by the routing table for the same destination node.When one routing is interrrupted in communication,the node can directly switch another route,thereby reducing the probability of packet loss due to no routing and improving the reliability of data transmission.Simultaneously,the LDPV protocol compresses the data volume of the routing message from a complete path tree to a fixed-size array,which improves the efficiency of routing packets and reduces the control overhead of the network.In addition,the triggering mechanism of routing packets is introduced to the proposed routing protocol,that is,the node sends the routing message immediately after satisfing the specific condition,shortening the convergence time and further improving the overall performance of the network.In this thesis,the performance differences between LDPV routing protocol and traditional ad hoc network routing protocol are compared and analyzed by self-developed ad hoc simulation platform from three key indexes of packet delivery ratio,convergence time and routing overhead in the scenarios of different network sizes,network topology rates and network traffic.The simulation results show that the LDPV protocol is more suitable for large-scale load-heavy networks than traditional ad-hoc routing protocols,and achieves good optimization results in improving data transmission reliability,reducing routing overhead and shortening convergence time.