| DTN network is a special network which is different from the traditional Internet network.There are great differences in communication delay,network structures and data transmission rates between them.In such a special network,traditional routing protocols and network structures can't be applied.In the special network environment of DTN network such as Space-Air-Ground information network and Ad-hoc network.If efficient routing algorithms can be used in such special networks,the stability of the network links and quality of network services can be improve.However,the traditional DTN routing protocols have many inherent drawbacks and hard to be improved,such as the multicopy of key packets,the system bandwidth occupied by copies and the aggravation of network links.Common DTN routing protocol is analyzed in detail,especially ER and CGR routing protocol.With the birth of the network coding idea based on Shannon's "max flow minimum cut" theory,it provides a new idea for the improvement of the traditional DTN routing protocol.In this paper,based on the research of traditional DTN network routing algorithms and common network coding algorithms,the schemes to combine the network coding algorithm with traditional DTN network routing protocol are put forward.The main work and achievements of this paper are summarized as follows:(1)The common DTN network routing protocols and the common network coding methods are classified and summarized,the advantages and disadvantages of them and their application networks are described brief.(2)The computational complexity of each common network encoding algorithm is analyzed.The characteristics of the growth code algorithm and the cyclic code algorithm are summarized,which can improve the bandwidth problem of the multiple replication of the key packets in the original DTN routing protocol.(3)On the basis of the analysis of the above theoretical ideas,a Growth Code algorithm based Epidemic Routing protocol and a Cycle Code algorithm based Contact Graph Routing protocol are proposed to solve the problem of network bandwidth utilization and aggravation of network links by key repetitive packets,and a detailed coding and decoding scheme is designed.Using the time as the degree distribution points of encoding algorithm and the reducing decoding algorithm.(4)STK simulation tool is used to build the 8 node topology like Earth-Mars network.The track information of the network node is referred to the orbit information of the orbit satellite.Based on the STK simulation model,the virtual network node is set up in the CORE software platform and the same flat surface network topology is built,and the ION simulation platform is used.Each virtual node is set to DTN node,and the contact window data obtained by STK is configured to CORE virtual node.After the configuration of the network nodes is completed,the network coding encoder and decoder are added at the network nodes,and the network coding algorithm is integrated into the built Earth-Mars communication model for simulation verification.(5)Finally,the simulation of two performances of the successful packet delivery rate of packets and the average transmission delay of the data packet based on the Cycle Code algorithm based Contact Graph Routing protocol is completed.It is concluded that the improved CGR routing protocol has higher rates of successful packet deliveries and lower average transmission delay than the original CGR routing protocol. |
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