Research On Dynamic Routing Algorithm For LEO Constellation

In LEO constellation system,the dynamic topology and complex space environment increase the probability of link interruption and reduce the reliability of routing algorithm.In order to reduce the impact of these two factors on the routing,this thesis introduces the basic idea of snapshot subgraph to characterize the satellite dynamic topology,but the traditional satellite network topology snapshot subgraph only represents the satellite information at a certain time,ignoring the time-varying of satellite network link resources and node storage resources,resulting in the routing state information update is not timely,leading to unreliable data transmission.To solve the above problems,in the LEO satellite network scenario,this thesis establishes a dynamic topology prediction model of LEO satellite network by considering the time-varying link resources and node storage resources,predicts the topology evolution of the satellite network,and proposes a routing algorithm based on the model to improve the reliability of data transmission.The main work is as follows:Firstly,in order to accurately depict the dynamic topology of LEO satellite network,a spatiotemporal graph topology model of satellite network is established according to the motion law of LEO satellite,and discrete and orderly snapshot subgraphs are obtained.The parameters of signal-to-noise ratio,buffer queue length and link stability of satellite network are modeled respectively,and the gap connection relationship model of snapshot subgraphs is constructed by integrating these three models to obtain snapshots The dynamic topology model of LEO satellite network is described by combining space-time graph topology model and snapshot subgraph gap connection relationship model.Then,in order to improve the reliability of data transmission in LEO satellite network scenario,a spatiotemporal graph routing algorithm based on link attributes is designed based on the established dynamic topology model of LEO satellite network.According to the signal-to-noise ratio,buffer queue length,link stability and other parameters of LEO satellite network,the algorithm establishes a link reliability model by using multi-attribute decision-making theory to evaluate the link performance,proposes a deviation maximization algorithm to adaptively allocate the weights of three parameters in the link reliability model and combines the link reliability evaluation model and the weight adaptive allocation algorithm to optimize the link performance.The routing decision-making problem of spatiotemporal graph routing algorithm based on link attributes is transformed into multi-attribute decision-making problem,and the multi-attribute decision-making problem is solved to select the optimal transmission path.Finally,the algorithm is simulated to analyze the impact of different data duration and different data transmission rate on routing performance.Experimental results show that,compared with the existing routing algorithms,the proposed spatiotemporal graph routing algorithm based on link attributes improves the system throughput,reduces the network delay and packet loss rate,and achieves more reliable data communication.