Research On Inter-satellite Link Topology Control And Routing Algorithm For Satellite Network

Satellite network system has the advantages of long communication distance,strong scalability,and global coverage.They are widely used in defense construction,military investigation,scientific research,and resident life.The inter-satellite link(ISL)can make satellite nodes cooperate with each other to form an organic whole and improve the communication performance of the satellite network.Therefore,it plays an increasingly important role in satellite communication.Due to the time-varying characteristics of the satellite nodes,the on-off characteristics and visibility of the inter-satellite links are constantly changing during the constellation operation period,which brings challenges to the implementation of the routing algorithm.Therefore,how to shield the dynamic characteristics of the satellite network and establish a stable inter-satellite link topology to achieve inter-satellite link routing algorithm with a good communication performance becomes a key issue.Based on the MEO/GEO double-layer satellite network architecture inter-satellite link networking model,the topology control is achieved by planning the link time slots and objects of the inter-satellite link.And then the routing algorithm is designed based on the topology control results.The simulation results show that the routing algorithm has good communication performance.The main research results of the thesis are as follows:Firstly,the MEO/GEO double-layer satellite network architecture inter-satellite link networking model is established based on the Walker constellation.Through simulation analysis of geometric parameters of inter-satellite links,inter-satellite visibility and satellite-ground visibility,the variation rule of inter-satellite link topology attributes are summarized which provides a research basis for topology control strategies.Secondly,the research and implementation of the inter-satellite link topology control strategy is carried out according to the variation rule of the inter-satellite link topology.Based on the Space/Time-Division Multiple Access(STDMA)system and the virtual topology strategy,the inter-satellite link topology control model is established and implemented by planning fixed links and time-varying links.And the topology control planning results in each superframe are obtained through simulation.The strategy determines the inter-satellite link network topology in each STDMA time slot and the network topology variation rule between time slots.The simulation result of the Chain Dilution of Precision(PDOP)shows that the topology structure of the inter-satellite link network under the control strategy is relatively stable.Finally,based on the inter-satellite link topology control planning results,an inter-satellite link routing algorithm is proposed.For different types of inter-satellite link services,the service feature parameter set is established to provide a unified input for the routing algorithm.The routing algorithm uses the shortest time slot path as the service path finding standard.By establishing and updating the reachable matrix and the shortest time slot matrix in real time,the service pathfinding is completed on the inter-satellite link topology control matrix.In the implementation process of the algorithm,the cross-frame transmission mechanism is designed to solve the problem that the service trans mission cannot be completed within a superframe,and the service queue processing mechanism is designed to solve the service conflict problem.Finally,the communication performance of the routing algorithm is verified by simulation.