| In recent years,many emerging network,including vehicular Ad-Hoc network,Inter Planetary Internet(IPN),space optical communication network and other networks have emerged.Due to the high mobility of nodes,energy scheduling,environmental interference and other factors,these networks may cause frequent interruption of connections between nodes.These networks have very distinctive characteristics: intermittent connectivity,high latency,random dynamic changes in topology,limited node resources,and so on.Such networks are called "Delay/ Disruption Tolerant networks(DTN)".At present,as a new end-to-end storage and forwarding system,Delay/Disruption Tolerant Network has become one of the most popular research topics in the field of wireless networks.In the satellite network,the satellite nodes run according to the preset orbit,resulting in a dynamic change in the network topology.But the trajectory is predictable,so the satellite network is a special DTN network.Satellite DTN network complexity is high.The node moves constantly,so the whole network topology has been in a rapid and dynamic change,and the routing technology is more complex.At the same time,because of the special environment,the node’s storage resources and communication resources are limited.Node congestion and corruption can result in data loss and long delay.Therefore,routing technology,successful packet delivery,congestion control and survivability technology are the critical issues in satellite DTN networks.This paper focuses on the routing strategy and the survivability of multi-layer satellite DTN network.(1)Based on the research of the DTN network and satellite DTN network routing technology in recent years,the significance of the research on the routing,congestion control and survivability of the multi-layer DTN network is clarified.According to the research status of satellite DTN network and routing technology in DTN network,the key technical problems are pointed out.(2)This paper introduces a typical multi-layer satellite network,builds a 12LEO+1MEO satellite constellation and a 3GEO+12LEO+1MEO three-layer satellite constellation,and generates a report on the visibility between satellites in satellite constellations.(3)This paper analyzes the traditional DTN network routing technology-ED algorithm,and then improves the ED algorithm for alleviating node congestion and the characteristics of satellite network,and proposes a dual path distributed ED algorithm.According to the traditional DTN network routing technology--ED algorithm,combined with the characteristics of the satellite network,the ED algorithm is improved,and a dual path distributed ED algorithm is proposed.The algorithm adopts the virtual topology routing strategy and joins the distributed routing algorithm to improve the path calculation and path selection.The algorithm consists of two parts:(1)path calculation,using time-varying Dijkstra algorithm to calculate two paths for each pair of nodes,there is no overlap path between two paths,at the same time as much as possible to reduce the presence of the same node;(2)Path selection,each satellite node maintains two routing tables.When the message is sent,if the next hop node is congested,it can quickly query another routing table to select a new path for forwarding.(4)Because the invulnerability of dual path distributed ED algorithm is poor,in order to improve the invulnerability of the network,a dual path distributed ED algorithm is proposed by adding GEO satellite to fault data collection and auxiliary routing.Construction of OPNET/STK/VS2010 Joint Simulation Platform,Simulation of Dual Path Distributed ED Routing Algorithm and Resistant Dual Path Distributed ED Routing Algorithm.Collect simulation results and analyze.The algorithm can improve the packet delivery rate,slow down the node congestion,enhance the survivability and improve the resource utilization. |
