Research And Improvement Of Opportunistic Routing Algorithm On DTNs

Delay-tolerant networks(DTNs)are intermittently-connected networks that may suffer from frequent or long lasting disconnection due to various reasons such as power management, mobility, scheduling etc.DTNs cover the intermittently-connected due to node’s moving, the periodic-connected satellite networks, wildlife-tracking networks, mobile Ad hoc networks and personal equipment switched networks etc. This thesis focuses on unicast routing problems on DTNs,then analyzes the advantages and disadvantages of the existing unicast routing algorithms.In some part of DTNs, node’s mobility path and scheduling information are unpredictable, which show the characteristics of opportunism, they reflect most of the scenes of the real life,so the research of opportunistic routing algorithm has high academic and practical value.This thesis focuses on the opportunistic routing of unicast routing and emphasizes on two of opportunistic routing algorithms named Simple Counting and Delegation Forwarding. And this thesis also analyzes the advantages and the disadvantages of the two algorithms—simple counting algorithm forwards the message to the nodes with low forwarding probability causes the waste of energy and cache resources,and delegation forwarding algorithm forwards message to the nodes with the highest quality causes the large average delay of the networks. As a result, this thesis proposes a new routing algorithm named SCDF (the combination of Simple Counting and Delegation Forwarding) which is based on Simple Counting and Delegation Forwarding.Finally, this thesis use the ONE simulation software to simulate the Simple Counting,Delegation Forwarding and SCDF algorithm in different conditions such as different node density and mobility model etc.. Then, this thesis evaluats the SCDF algorithm performance through the successful transmission rate of packet, average delay and the average number of packet copies in the network.The result proves that the SCDF algorithm has low network latency, high successful transmission rate and greatly reduce the number of packet copies in the network, SCDF algorithm has better robustness and performance especially in a large node density.