Research About DTN Routing Protocol Of Deep Space Network

Interplanetary Internet or Interplanetary Networking(IPN)is envisaged as a space network which interconnects spacecrafts,satellites,rovers and orbiters of different planets and comets for efficient exchange of scientific data such as telemetry and images.IPNs are classified among challenged networks because of the unpredictable changes in the network and the large varying delays in communication that make the TCP/IP protocol unsuitable in IPNs.Delay Tolerant Net-working(DTN),in its different implementations,is one of the suggested solutions to overcome these networks' challenges.DTN suggests that routing in DTN should base on the ‘storage-carryingforward' routing strategy.DTN has different routing techniques,among which Contact Graph Routing(CGR)is widely utilized in IPNs.Based on the CGR routing protocol in DTN network,this thesis focus on the reach at the adaptability and efficiency of the algorithm under the conditions of long delay and frequent interruption,the improvement ideas are put forward,and the performance and practical situation of the improved algorithm are verified and compared.The main contents include:Firstly,this introduces the characteristics of DTN network and the problems of routing.As the DTN network topology changes frequently,the communication links are interrupted frequently,the link is long delayed and variable,and in the deep space IPN network,the storage space and energy of the satellite nodes are limited,which leads to the low delivery rate and long average delay.And the existing routing algorithm based on replication strategy and forwarding strategy routing algorithm cannot be fully applicable to deep space IPN environment.Secondly,the CGR routing protocol is studied.Although the CGR routing protocol has been widely used in IPN network,through the principle analysis and simulation of the algorithm,it is found that the Dijkstra algorithm is used in the CGR algorithm,which only considers the next hop of the contact window time and the remaining capacity of the node,do not take into account the remaining capacity of other contacts that may reach the destination node in the future,so that the data may be transmitted to a relay node if the remaining capacity at this time is insufficient or exceeds the bundle survival time,the bundle will be discarded,causing the bundle to fail to transmit to the destination node.Thirdly,based on the characteristics of DTN network in deep space IPN,CGRMTG based on MTG model is proposed for CGR routing protocol.The algorithm uses MTG(Modified Time-varying Graph)model,which combines the characteristics of DTN network and optimizes the storage space of time-varying graph,and its algorithm is used to detect the residual capacity of all paths.The method used to represent Contact Plan is more efficient than the enumeration method in the CGR algorithm.Lastly,based on the communication scene of the Earth-Mars Orbiter-Mars,the space network topology of the Earth-Mars is designed.The DTN network protocol is adopted,and the routing protocol uses the CGR-MTG routing protocol.A satellite simulation environment is set up,and the earth station,Mars orbiter and Mars lander were set up.The STK(Satellite Tool Kit)satellite toolbox was used to simulate the motion trajectory of the simulation node,and the spatial network data was generated.ION(Interplanetary Overlay Network)simulation platform for simulation.By changing the size of the transport bundle,the CGR-MTG algorithm is simulated and verified by the CGR-MTG algorithm.The results show that the CGR-MTG algorithm has the advantages of message passing rate,average delay and network throughput are superior to CGR algorithm.