The Research On Routing Protocols In Ad Hoc Network

With the development of wireless communication technology,more and more mobile terminals emerged,which leads to the requirements of stronger and more stable networks.Because of the high cost for establishing and maintaining the fixed infrastructure,as well as the strong mobility of terminals,Ad Hoc network,which has the features of no need for base station,fast networking and high survivability,has drawn much attention.As the hotspot and difficulty of the Ad Hoc network research,routing protocols caught many attentions of researchers,and a lot of routing protocols have been put forward.But it's still necessary to design a special routing protocol for each scene according to its unique characteristics.In this paper,we firstly introduce the Ad Hoc network and analyze its characteristics.According to the speed of moving nodes,the scene can be divided into two types.One is the scene of static or low-speed moving nodes,and the other is the scene of high-speed moving nodes.In this paper,data network of smart home is taken as an example for the former and VANET in urban environment is taken as an example for the latter.Two routing protocols are designed and simulated for these two scenarios.In the scene of static or low-speed moving nodes,a time-slot routing protocol(TSRP)of smart home data network is proposed to resolve the congestion problem.Smart gateway selects one node with better performance in its neighbor nodes as a cluster head.Taking the area of house,the number of terminals and transmission power into account,the cluster head can communicate with all nodes within three hops.In this protocol,the process of routing discovery is started by the cluster head,and the nodes in a home are automatically divided into three levels according to the strength of received signal and can be controlled by the cluster head to access the Internet in order.Just as its name implies,a slotted scheme is considered here,and the maximum retransmission is set to five.In order to enhance the routing stability,a multiple constrained routing algorithm is adopted to choose one route to send reply packet,then the routes between cluster head and all nodes are saved to the routing tables.After modeling and calculating,the average time of each level nodes to access the Internet is obtained,so that the average time of all nodes to access the Internet is obtained as well.Finally,the optimal number of slots and the corresponding average time to access the Internet for different number of nodes are given by MATLAB simulation.In the scene of high-speed moving nodes,VANET in urban environment is taken as an example to design a routing protocol.The traffic flow can be divided into four conditions according to the nodal density of VANET.For each condition,a brief introduction of corresponding routing protocol is given.In order to avoid the problem of broadcast storm in network,and enhance the lifetime of network,a routing protocol called probability based energy and load balanced AODV(PBEL-AODV)is proposed in this part.Probability based forwarding formula,data packets' format and data processing scheme are also designed in this part.The simulation results which obtained by NS2 show that PBEL-AODV performs better than AODV in terms of end-to-end delay,packet delivery fraction and normalized routing overhead.We also give a method to build a Linux based testing platform.Some tests are also given to verify the functions of the Ad Hoc routing protocol,which lay a good foundation for the following work.