Message Transmission Research In Opportunistic Social Networks

With the development of mobile terminal devices, the applications become increasinglycommon which is carried by a person for message transmission in opportunistic network. Dueto there is a particular social relationship between people, and the services of social networkare constantly upgrading, the opportunistic network is gradually evolved into theopportunistic social network. There is on fixed network infrastructure in opportunistic socialnetwork, people will carry all kinds of mobile intelligent devices in this network. It alwaysrelies on the strength of human social relationships, and through the node movements to bringthe opportunities of communication, also uses the mode of “store-carry-forward” to realize theforwarding of a message. The topology changes constantly, and it does not exists stableend-to-end communication links between nodes, the network delay is larger. Therefore,whether the selection of the next hop node is reasonable, has become the key factor whichaffects the network performance.This paper first introduces the research background and significance, the current researchstatus at home and abroad, the basic concepts, the network characteristics, the main practicalapplications, the key problems etc. in the opportunistic social network. Then we analyzed therouting algorithms and the node mobility models which were existed. Although somealgorithms may have better performance in a specific network environment, but they do nottake into account the actual movement characteristics and the social relationships between thecarriers. So it will be introduce the social characteristics of human and the communityfeatures into the design of the message transmission is very necessary. At the same time, someof the nodes do not have too much connection relations with other nodes in the network, thesocial relations are very weak, and they are unwilling to forward the message to other nodes,showing strong selfish characteristics. If it exist “selfish” nodes in very large quantities in thenetwork, it will have a negative impact on the performance of the network. Therefore, weshould consider the selfishness of the nodes, and take certain measures to reduce this behaviorto affect the performance of the network.1) Due to the existing routing algorithm is only concerned about the node mobilityimpacting the performance of the network, and not fully take into account the carrier of the mobile device, the community gathering and the social mobility characteristics of the people.Aimed at this problem, we put forward an integrated routing algorithm which based of thestrength of the human social relationships and its mobile features, and it also limited thecopies of the messages. In this algorithm, firstly, it will according the number of encounters ofthe node pairs, and calculate the encounter probability to determine the strength of the socialrelationships and then it will separate dynamically of the nodes into different movingcommunities; secondly, the routing algorithm will dynamically according to the number ofcommunity and the encounter probability to limit the copies of the messages. It not onlyachieve multi-path parallel the transmission of the message, but also can more effectivelyreduce the redundancy of the transmission of data and increase the utilization of the networkresources; finally, it will make use of the active node which have high weights to driven thenodes to spread the message and by using the manner of diffusion confirmation messages toachieve the scientific and effective management of the node cache. This routing algorithm canguarantee a premise of a higher success rate of the message transmission, and show therelatively lower transmission latency, and as well as lower cost performance of the networkresource than PROPHET, Spray and Wait these two both traditional routing algorithms.2) This paper also for the phenomenon of there are some “selfish” nodes which are notwilling to send messages in opportunistic social network, we propose an efficient routingmechanism based on cooperation degree of nodes. By fully studying the social characteristicsof user’s movement, taking advantage of the method of trust level in economics to deal withthe problem of selfish nodes, according to comprehensive consideration the information ofnodes, such as user similarity and credibility and the ability of cache and so on. It will choosethe node of high social cooperation degree acts as intermediary broker to forward the data, thedata is forwarded always along the path of higher value of cooperation degree. It caneffectively improve the success rate of the message transmission and reduce the networklatency. When the core value of some nodes is below a certain threshold in the network, wewill adopt the method which is isolating them, these nodes will not forward the data any more,thus it will reduce the cost of the network resources.