A Research On Routing Algorithms Of Delay-tolerant Wireless Sensor Network

With the development of wireless sensor technology, the related applications beginto appear in recent years, as a result, the related researches in wireless sensor networksbecome a new hot topic. It is well known that network routing problem is a core issue inthe research of computer network. While the wireless sensor network is a typical delaytolerant network where the random movement of nodes can cause intermittentconnectivity which brings a great challenge to design routing protocol. In order tosolve the intermittent connectivity problem of sensor network, we usually use thecarry and forward routing policy, that is, nodes always carry messages moving untilthey encounter proper relay nodes, then they will relay the message in the form ofmultiple hops. Therefore, the performance of corresponding routing algorithm is largelydependent on the intermediate nodes. some applications in wireless sensor networks,the nodes in the network will show a corresponding social selfishness that these nodeswant to reduce their overhead by refusing to relay messages to other nodes. When thewireless sensor networks behave such phenomena, the performance of the routingalgorithm will be seriously affected. Thus, we urgently need to take some appropriatemeasures to reduce the effect of the selfishness to the network’s performance.This thesis mainly researches on routing algorithm based on the social selfishnessfor the wireless sensor network node. Firstly, we analyze the reason of the nodes socialselfishness in the network and discuss the effect of selfish nodes on some typicalrouting algorithms in wireless sensor networks. Then, we introduce the nodes’credibility,which can be used to evaluate the selfishness of nodes. Finally, we propose anew routing algorithm based on the characteristics of networks selfishness. The newalgorithm is divided into two stages. In the first stage, we mainly complete the spread ofcopy message. Taking the node selfishness impact on network performance into account,we apply the design of the number of copies proliferation based on a certain credibilitythreshold, which can ensure the diffusion rate of the late copy messages. In the secondstage, we predict the next position of the nodes based on first-order Markov locationprediction model, according to the predicted results, message will do greedy delivery to the direction of the destination node. In addition, in order to reduce the effect of numberof copy messages on the network performance, we employ application layer’s delayconstraints to control the number of corresponding copies in the network. According tothe results of simulation, we can conclude that our algorithm, compared with the otherseveral typical routing protocols such as Spray and Focus、Spray and Wait, has higherdata delivery ratio, lower message latency and with respect to Epidemic, our algorithmconsumes less network resources.