Routing Algorithm For Opportunistic Networks

With the rapid development of mobile wireless communication technology and mobile terminal technology, Mobile communication has become an important way of communication for people to get information and service from the Internet no matter when and where even for moving. However, the traditional wireless communication has to use some infrastructure (such as base station) to ensure the communication between the communication nodes to complete the communication, which make it difficult to communicate without infrastructure to deploy in the harsh environment, in order to solve this problem, a new type of network is proposed-the opportunity network. Opportunistic network has many features of delay tolerance network. Nodes no having the nature of uniform deployment, no need of default network size and node initial position, and there is no need to determine if there is a path when communicating to the end. So the opportunistic network can solve the problem of communication in frequent discontinuous networks. It can be used in emergency rescue, military mobile network environment and so on. At the same time, the complex topology of network, the capacity of the limited network and the lack of network communication information have brought the huge challenge to the researchers. Routing algorithm research and design become a very important link, The advantages and disadvantages of the algorithm directly affect the performance of the network.I have done a lot of research on routing protocol, found that the opportunistic routing protocol in probabilistic routing, epidemic routing mechanism did not involve both of two factors:the node contact frequency and contact time, which causing some limitations and deletions. To solve this problem, HMPR algorithm is proposed by LIU Qilie, XU Meng et alto improve the existing performance, this algorithm has advantages over the traditional routing is higher delivery ratio, but not very good improvement in routing latency problems. So in the third chapter a redundant hybrid routing algorithm based on historical utility(HHRA) was put forward, HHRA. The HHRA algorithm is based on the node history information (encounter interval, the frequency of the encounter and the reliable transmission efficiency) of the node forwarding utility, and its forwarding strategy is based on the multi copy control mechanism. Results of the simulation, the proposed HHRA algorithm has improved transmission success ratio and reduced transmission delay compared with the traditional route and flooding route and HMPR algorithm.During the studying on the forwarding protocol, I found that most of the existing protocols are based on the assumption that the nodes are completely random, and it is little to use mobile characteristics for protocol design, neglecting the mobile rule of nodes in real scene. Such as human, animal, car, etc., they have certain mobile features, if we can make full use of node movement law to forwarding protocol that would be beneficial and feasible for research methods. The BMCU algorithm proposed by SHU Jian, DONG Hai-xing et al was forwarding mechanism utility based on the mobile characteristics, but the algorithm have serious obvious shortcoming, the similarity of the relay node and the target node is not considered in the forwarding strategy. If the similarity of the relay node with the source node and destination node is higher than the threshold, it will cause false judgments and hinder the successful transmission of messages. In addition, the active degree of the model is not perfect and the utility value of the reference is only active degree without consideration of intimacy can not guarantee the reliability of communication. So the algorithm has been made an improvement in the fourth chapter:a intimacy between nodes was proposed and the similarity model was improved, by comparing with the node similarity, if the similarity is less than the threshold, comprehensive consideration the similarity of the relay node with the target node, intimacy, activity and residual energy to measure forwarding utility value. The message forwarding based on the multi-copies control strategy inhibiting the copies of messages. At last simulation results show that the improved IBMCU algorithm has better performance compared with BMCU algorithm about the stability, while the delivery rate was improved and the average delay was reduced.