Research On Routing Algorithms Of MEO/LEO Satellite Networks

Satellite network is an important part of the space-ground integrated information network.The LEO(Low Earth Orbit)satellite internet has the characteristics of low transmission delay,low communication link power loss,and low launch cost.Through inter satellite links and networking technologies,the LEO satellite Internet can provide communication services with global coverage.It can provide greater support to the traditional terrestrial Internet in the aspect of coverage and mobile access.In recent years,the LEO satellite Internet has attracted wide attentions from global scholars due to the development of the space-ground integrated information network and the reduction of the cost of LEO satellites.Under the scene of dynamic changes in the LEO satellite network topology,the design of efficient LEO satellite network routing algorithms become one of the research hotspots.Based on the LEO satellite constellation model and the MEO(Medium Earth Orbit)/LEO double-layer satellite constellation model,this thesis proposes the LEO satellite communication network routing algorithm based on inter-satellite link state and the double-layer satellite communication network routing algorithm.At last,the performance of the proposed algorithms are analyzed by simulations.The main contributions of the thesis are as follows.(1)For the LEO satellite communication network scenario,the routing algorithm based on inter-satellite link state is proposed and the algorithm is divided into link state detection,routing calculation and routing modification phase.In the link state detection phase,link state information is periodically obtained,and the 12 inter-satellite link state information are recorded locally.In the routing calculation phase,the satellite logical address is used to calculate the hop count,transmission direction and priority of transmission.Then the initial routing path can be determined.In the routing modification phase,the local link state table is queried to modify the initial routing path.The simulation results show that the packet loss rate of the proposed algorithm is about 10% to 25 % lower than the routing based on virtual topology and routing based on virtual nodes.(2)For the MEO/LEO satellite communication network scenario,the routing algorithm based on grouping management is proposed and the algorithm uses MEO satellites to provide routing calculation and data forwarding services for LEO satellites.In the proposed algorithm,the LEO satellites collect link delay and congestion information,and then the MEO satellites use delay and congestion factors as weights to calculate the routing table by the shortest path algorithm.In addition,for the routing hop count problem in long-distance communication,the MEO satellites can be used to forward data.The simulation results show that the performance of the proposed algorithm is better than the single-layer LEO satellite communication network.