Research On Congestion Control Based On AODV Routing Protocol In Ad Hoc Network

Ad Hoc networks are multi-hop,self-organizing,and non-central,with great flexibility.It is precisely because of the dynamic diversity of Ad Hoc networks and the frequent changes of network topology that many traditional routing protocols cannot meet their needs.Therefore,Ad Hoc network routing protocol is one of the hotspots in the field of network research.At the same time,the bandwidth resources of the Ad Hoc network are very limited.When the network is congested,the quality of the network and the performance of the network may be seriously affected.The uneven load and resource allocation may cause congestion in the Ad Hoc network and even link breakage.The current solutions for congestion control improvement mainly focus on the transport layer,network layer and data link layer.The author chooses to research the network congestion problem by improving the routing protocol at the network layer.In this paper,the on-demand routing protocol AODV is deeply studied.It is compared with the other two classic Ad Hoc network routing protocols DSDV and DSR on the simulation software NS2.The simulation results are analyzed and the advantages and disadvantages of the three protocols are compared.The AODV protocol can be said to be a combination of the DSDV protocol and the DSR protocol to some extent.It can be seen from the simulation results that the performance of the AODV protocol is superior to the DSDV protocol and the DSR protocol.Then,based on the AODV routing protocol,this paper proposes an improved protocol VHAODV based on virtual hop count.In the process of calculating the forwarding hop count,the load condition and energy of the node are taken into consideration,and the virtual hop count of the load is defined.And the concept of the virtual hop count of energy,the value of the virtual hop count is determined according to the load and the energy,and finally the path with the smallest virtual hop count is selected.The simulation proves that the performance of the VHAODV protocol is better than the AODV protocol in packet delivery rate and network average delay,which shows the VHAODV protocol alleviates congestion.Finally,another improved routing protocol IPS-AODV based on AODV protocol is proposed.In the route discovery period,the intermediate node processes the received RREQ messages differently according to its own congestion and energy consumption,avoiding the nodes with large load and insufficient energy.A new criterion based on load and energy is defined.Updating the route according to the principle of the smallest criterion and choosing a path with average load and average energy are relatively balanced.In the route maintenanceperiod,the Hello message mechanism is improved.The Hello message switch flag is set.When it is detected that the node has a control message or a data packet is being sent,the Hello message switch is set to the off state.This can avoid broadcasting a large number of useless Hello messages and reduce the burden on the network.The simulation proves that the improved IPS-AODV protocol is superior to the AODV protocol in terms of network average delay,control overhead,route initiation frequency and packet delivery rate.