Research On The Improvement Of Spray And Wait Routing Algorithm Based On Node Reputation

Mobile opportunities network is a new type of mobile ad hoc network.Traditional networks need a complete path between the source node and the destination node to communicate.However,in mobile opportunity network,there is no need for fixed lines between nodes.There are the characteristics of nodes moving constantly,frequent network topology changes,no fixed link between nodes,high transmission delay,limited node resources,and poor security.Due to these characteristics,the design of efficient routing algorithm is the primary problem in the field of mobile opportunity network research.Mobile opportunity network adopts the message exchange mechanism of "storage-carry-forward".Every time a node receives a message,it first stores it in the cache,and then carries it all the time waiting for a suitable communication opportunity to complete the forwarding.Because the mobile opportunity network does not need a stable end-to-end communication link between the source node and the destination node,it has become a research hotspot in the field of wireless communication in recent years,such as providing location service,intelligent transportation system,battlefield communication network,wildlife monitoring network,etc.This paper introduces the concept and research of mobile opportunity network,and analyzes the research status of node reputation in mobile opportunity network by domestic and foreign researchers.In this paper,the typical routing algorithms of the current mainstream mobile opportunity network are explained in detail,and the one platform used in the mobile opportunity network simulation experiment is introduced.Because the nodes in the network have great differences in the ability to transmit messages,and there are selfish nodes in the network,the overall load of the network will increase,and the transmission success rate will decrease.So this paper improves the traditional Spray and Wait algorithm in the Spray stage,and optimizes the original cache management mechanism,and proposes an improved scheme based on the reputation of the node(spray and wait based on node reputation,NR-S&W).The main work of this paper is as follows:(1)A spray strategy based on node reputation(NR-SS)is proposed.In this algorithm,each node in the network is asked to maintain a reputation table about the node it meets.When the node meets,it judges whether to pass the message to the node it meets according to the reputation table.On this basis,the calculation formula and maintenance strategy of node reputation are put forward.Each node in the algorithm has an ACK table to clear the communicated messages.According to the algorithm,the node will deliver the message to the direction of high reputation to improve the delivery rate of the whole network.(2)On the basis of the above paper,an improved scheme of spray and wait routing algorithm based on node reputation(NR-S&W)is proposed.This scheme mainly aims at the cache management part,contacts the node reputation table,and improves the message cache management of nodes.At the same time of ensuring the message delivery rate,the best decision-making scheme for cache management is made according to the message quality.A dynamic message copy strategy is proposed to determine the number of message copies according to the network environment.This scheme will make the routing policy tend to delete messages with low quality,so as to improve the delivery rate of the whole network.One simulation platform is used to simulate the algorithm in this paper,and compare with other algorithms.The simulation time,cache size,message lifetime and node selfishness ratio are compared.The advantages and disadvantages of the algorithm are analyzed by comparing the transfer rate,average transfer hops,network load,etc.The simulation results show that NR-S&W algorithm can select the nodes with high transfer probability more accurately,improve the delivery success rate,and reduce the transmission overhead and the average number of transfer hops.