Research On Routing Mechanisms For Opportunistic Social Networks

With the development of communication technologies and the spread of smart mobile devices,the Internet covers from fixed terminals to mobile ones gradually.To meet the needs of the variety and coverage of the Internet services,opportunistic social networks(OSNs)emerge,and becomes a hotspot in the area of information and communications rapidly.OSN is the combination of social network and opportunistic network.By the store-carry-and-forward communication paradigm,OSN can make communications in the network without stable end-to-end connections,through the communication opportunities created by nodes' encounters.Due to the specific nature of ONS,its routing could be decomposed into two parts,next-hop selecting for messages and buffer management for nodes,which can both be benefit by the use of social relationships among nodes.Accordingly,this paper aims at solving message forwarding and buffer scheduling problems,getting the social attributes analysis of messages and nodes involved in as a tool.The main research contents are organized as follows.Firstly,a message forwarding strategy based on chain of events analysis for OSN is presented to increase the delivery rate and reduce the transmission delay of messages in the process of routing.Based on clustering analysis,nodes are divided into clusters in which nodes have a high probability of encountering and message forwarding.Different forwarding strategies are applied to inter-message and intra-message respectively,aiming to optimize the process of message forwarding and relay node choosing.Besides,chain of events is used in clustering to analyze the space-time characteristics of events resulted from nodes communication.Experimental results show that it can lead to a higher delivery ratio and a lower delivery delay than some exisiting strategies in large complex networks.Secondly,a message dissemination based on interest matching for OSNs is proposed to improve the message dissemination performance and promote the experience for users.Considering the matching problem between the node's interest and message type,the matching node is prior chosen to be the relay node,which provides a promotion on the ratio of message interested in the buffer.For this purpose,a joint clustering analysis method is proposed to handle both the tie strength of nodes and the matching degree of node and message,which can balance the user experience and dissemination efficiency.Simulation results show that the proposed scheme can both improve the capability of opportunistic social networks in terms of delivery rate,latency and buffer usage,and promote the performance of message dissemination systems in terms of efficiency,coverage rate and interest matching rate.Thirdly,a message ferrying routing for community OSNs is presented to improve the transmission ability of networks.It consists of two parts,the hybrid message ferrying scheme(HMFS)and local ferry route scheduling(LFRS).According to HMFS,the communication area is divided into overlapping horizontal/vertical ferry regions,in which there are sets of global ferries(GFs)and ferrying relay nodes(FRNs).GFs and FRNs collectively complete the forwarding process of inter-messages.LFRS based on dynamic weighted deficit round-robin aims to maximize the network throughput where nodes or flows distribute unevenly.Experimental results show that the routing can decrease delivery delay for inter-messages greatly,and bring a significant improvement in throughput of local networks.Finally,an intuitionistic fuzzy set decision based buffer strategy is promoted to handle the message queues in the buffer,which can make the limited buffer used reasonably,and relieve network congestion.Intuitionistic fuzzy set is used to describe the performance impact of the various message properties to the network.The decision result called scheduling utility value(UV),is gained by the generalized ordered weighted averaging operator.Message forwarding and dropping order is decided based on UV,to help lessen the effect of message discarding to the network performance.Experimental results show that the strategy can both improve the capability of opportunistic social networks in terms of delivery rate,latency,and promote the network performance by reducing the network overhead and average buffering time.