| DTN is delay tolerant networks, one covering layer architecture that with generic reliablemessage-oriented and located on top of various local area network was proposed in2002International Conference by Kevin, which is designed for limited network that with high latencyand intermittent broken characteristics to be communicate. For example, Star Network IPN(interplanetary network), Military Ad hoc networks, sensor networks, deep-sea exploration DTNnetwork of effective application. Compared with traditional networks, DTN architecture added aBundle layer of network, or coverage layer, which is located between the application layer andtransport layer, through the Bundle layer adopt "storage-carry-forward" thought and thehop-by-hop (HBH) transfer mode to realize the communication between nodes, and realizetolerate high latency and interrupt connection in harsh environment for network interconnectionfunction. This architecture can help to solve such network frequent link problems such as delay,jitter and high bit error rate.DTN network link based on the characteristics of intermittent disconnection, by use of themulti-copy routing protocol to improve the rate of successful submission information, but DTNnetwork using asynchronous transmission mode, there exist a large amount of redundantinformation copies in the network nodes, which consume large amounts of limited networkresources and lead to network congestion. Thus DTN architecture congestion avoidancemechanism is very necessary, however,the research for DTN at home and abroad mainly focusedon the DTN routing protocol, less for congestion avoidance strategy research. This article made asummary on the study of predecessors have done, and has a concrete research on the classicalcongestion avoidance strategy, put forward a new active congestion avoidance strategy, comparethe classic routing strategy for simulation and analysis.the specific contents are as follows:To thestate of the data packet information timely notification to the network nodes, the nodes in a copyof the data redundancy delete makes it hard for network congestion phenomenon occurs.1.Detailed introduction of DTN network research background and development process,described the DTN applications in domestic and foreign present research situation and theresearch of DTN congestion avoidance strategy. Made a detail state of DTN networkcharacteristics, system structure design, bundle layer operation mechanism. Analyzed thecongestion and flow control mechanisms in DTN network, laid the foundation of furthercongestion avoidance mechanism research.2.Analysis of the existing routing protocol and related congestion control strategy in DTNnetwork, routing and congestion control is mutual connection and mutual influence, the routingprotocol based on message copy easily lead to network congestion in the running process.Introduced congestion avoidance mechanisms that based on scheduling management, based on acopy of the discarded and based on the cache replacement strategy.3.AAC congestion avoidance strategy is proposed, the strategy based on binary spray and wait routing protocol which using copy mechanism.It is timely inform the state of the datapacket information to the network nodes and delete redundancy copies of information in thenodes makes it hard to occur network congestion phenomenon by using the congestion degree,ACK index and value of reserve right, etc.4.Using ONE simulation platform for AAC congestion avoidance mechanism to simulate,and compared with the Epidemic, the PROPHET, the Spray and Wait Routing classic algorithmstrategies, and the simulation experiment data shows that the high efficiency of AAC strategy. Itis a kind of congestion avoidance mechanism that with reasonable algorithm and suitable forDTN environment. |
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