The Research Of Cache Mechanism And Routing Algorithm Based On Community Opportunity Network

Opportunistic network is a new kind of self-organization Network which uses the encounter opportunity between two mobile nodes to achieve data communications. It is a solution of the data transmission problem in some frequently interrupted network. In Opportunistic network, the source and the target always not in the same domain network at a certain time because of its mobility, energy and many other reasons. The communication between nodes can’t be connected through the traditional wireless ad-hoc network protocols. Therefore, researching the network routing algorithm such as exploring how to make effective trade-offs among the loss rate, network delay and any other key factors which are used to measure the efficiency of network is becoming much more important.The communication of Opportunistic network contains three typical characteristics:1) High frequency movement of node, resulting in a long time of not connected and large data transmission delay.2) Data transmission is completely dependent on the node mobility, and therefore the decisive factor of the performance is its mobile model.3) Compared to traditional MANET (mobile ad hoc network), the message will linger around in the cache for a longer time and also the capacity of the cache mist be higher.After analysis the characteristics presented above, we know that the most difficult thing in the research of Opportunistic network is how to ensure reliable data transmission under the circumstance of high latency and high network uncertainty. During the data transmission, the mobile node in Opportunistic network use the model like storage-moving-forward, so we have to consider three aspects comprehensive. Based on this, the corresponding studies we have launched, the specific results are as follows:1) According to human activities, we proposed a community-based mobility model based on human movement. Currently nearly all of the researches about Opportunistic network are based on the model of random walk. The researchers did not adequately consider the impact of node mobility model to Opportunistic network performance. Also there is no research about Opportunistic network applying to our daily lives. In this paper the model simulates the characteristics of small-scale activities, and divided the activities scope into several communities, each node can join or leave the community when it is needed to do some data exchange.2) On the basis of the result1, after analysis the encounter probability and the interval, we introduce the priority of message (MP:message priorities) and propose a priority-based cache optimization strategy. Also design the cache model in the community and between the community, and future calculate the utility value of the message, put forward the corresponding cache replacement policy.3) According to the community-based mobility model, we both analysis the high probability dense living area of human and low probability remote areas of human, and fully consider four major influencing factors (message priority, the destination node matching rate node degree of trust, relay hops) which impact on the performance, according to the importance assign different weights, compare to a variety of programs to find the best. Then select the relay node, develop a reliable and efficiently routing and forwarding algorithms.Finally, computer simulation results show that the algorithm can effectively weigh the Epidemic and PROPHET algorithm to achieve a relatively optimal result, it reduce the average transmission delay and network cost, improve the data delivery success rate. And compared to other current opportunities network routing algorithm, the performance also has a big improvement accordingly.