Research On LEO Satellite Network Routing Strategy Based On Improved Pathfinding Algorithm

With the evolution of the space-integrated-ground network,the low orbit satellite network is a major component of the space-based backbone network in the nextgeneration communication network because of its low transmission delay,strong antidestructive capability,wide coverage,and flexible network configuration.Since low orbit satellites work in complex space environment,the size and performance of satellites are greatly restricted,resulting in limited computing and storage capacity of satellites.In addition,the service demand carried by satellites is affected by factors such as geographical environment,population distribution and network usage,resulting in imbalanced network load,which is also an important problem that needs to be solved in satellite networks.In view the above problems,this paper investigates the routing strategy in low orbit satellite networks.1.A routing strategy based on network congestion degree awareness is proposed.The idea of the proposed strategy is to select the routing algorithm dynamically according to the network state.The Dijkstra algorithm is used to find the shortest path when the network is in a non-congested state,while switching to en-BFS to find the path when the network is congested.In this paper,we propose the en-BFS algorithm based on the breadth-first search algorithm with a relaxation operation,which is able to find the path with linear time complexity in a topology with two-dimensional grid characteristics with guaranteed minimum number of hops and minimum weight sum,and its concise and efficient characteristics are well suited to the satellite environment with limited computing capability.Finally,through simulation experiments,the proposed strategy reduces the computational complexity while guaranteeing the network performance compared with other algorithms.2.A satellite routing strategy based on the balanced shortest path algorithm is proposed to solve the problem of imbalanced load on satellite networks.The routing strategy first introduces a population correction factor based on the population distribution as part of the weight consideration,and thus constructs the topology of the network.Then the optimal path is found and the routing table is constructed using the balanced shortest path algorithm proposed in this paper.In the process of finding the shortest path,this paper introduces the concept of virtual nodes and uses the idea of breadth-first search to propose a reinforcement breadth-first search algorithm to solve the problem of finding the shortest path.In addition,in order to solve the problem of high frequency of using certain nodes in the shortest path,the concept of extended path is proposed,and the reinforcement breadth-first search algorithm is improved to propose the extended shortest path algorithm to find out all the shortest paths as well as the extended paths.Then,based on the obtained results,the shortest path generation graph is constructed,based on which,by recording the node frequencies,appropriate paths are assigned to each node in turn.Finally,the simulation shows that the proposed algorithm effectively reduces the probability of node congestion and the network performance is significantly improved.