The Research And Implementation Of Multiple-Copy Routing Protocol With Acknowledgment Mechasim In Opportunistic Networks

Opportunistic Networks are one of the most important evolutions of Mobile Ad Hoc Networks.In Opportunistic Networks, due to nodal mobility, low density, lossy link, etc. there is no guarantee that a fully connected path between source and destination exits. However, the routing protocols used in traditional Mobile Ad Hoc Networks require at least one path existing from source to destination nodes. In consequence, these protocols can not work in Opportunistic Networks environment. Research on the routing protocols applied in Opportunistic Networks is always the hot investigation in Opportunistic Networks.In this paper, we firstly introduce Opportunistic Networks, including concept, development, current research situation and practical applications.Afterwards, we present the single-copy and multiple-copy routing protocols that applied in Opportunistic Networks.We introduce the concept and character of the two categories respectively and make a comparison between them. Based on the intensive study and analysis, we identify the defect of the multiple-copy routing protocols: lack of acknowledgment mechanism for the datagram that has been delivered to the destination successfully. The properties of Opportunistic Networks determine that the time to live of the datagram is quite long. In original multiple-copy routing protocols,because of the lack of acknowledgment, when a datagram arrives at its destination, the redundant copies of the datagram will stay in the network for a long time. These stale copies will waste the buffer space of nodes; incur redundant data exchange and other problems.Against the drawback of the current multiple-copy routing protocol, in this paper, we propose the multiple-copy with acknowledgment mechanism. When the datagram arrives at the destination successfully, the other redundant copies will be removed from the network in time through the acknowledgments. The multiple-copy routing with acknowledgment mechanism will reduce the consumption of the buffer, decrease the waste of link bandwidth and improve the success probability of datagram to be delivered. Finally, through the simulation, we verify that the acknowledgment mechanism enhance the performance of the original multiple-copy routing protocol.