Research On Routing Algorithm Based On Space-time Graph For Random Traffic In Satellite Networks

Nowadays,with the increasing demand for information,it is important to find timely,accurate and complete access to aerospace resources for various space missions such as resource exploration,topographic mapping,communication services for science and production activities,which requires the ability to acquire,transmit and comprehensively utilize spatial information.In the satellite network,due to the high-speed movement of the satellite,the on-off state of the link in the network evolves with time,making it difficult to have an end-to-end transmission path in the network.To solve this problem,this paper introduces a space-time graph to describe the dynamic topology of the satellite network and obtain the global information of the satellite network,and on this basis find the optimal path for the data which will be transmitted in the network to ensure the global optimal.In the traditional network traffic model,the unit increases with the time axis,the suddenness of the business is gradually reduced.Scientific research shows that in the satellite network,the suddenness of the actual network traffic does not change with the change of the time axis unit,which proves that the actual network traffic has self-similarity.The self-similarity of satellite network traffic makes it very easy for traffic to have a big sudden effect,in this case,if the data transmission paths are designed for data traffic in advance with a threshold of network traffic,link resource waste is extremely likely to occur,resulting in unnecessary transmission cost.In the existing method for solving the transmission problem of random traffic in the network,the main idea is to discard packets according to the established decision and dynamically allocat e bandwidth,but the first method will reduce the data transmission success probability,and the second method will increase the transmission cost because of the complicated allocation rules and the borrowing and releasing of the bandwidth mechanism.Therefore,this paper proposes a space-time graph based random traffic minimum cost routing algorithm for the above problems.Based on the space-time graph,according to the ON/OFF model,this paper proposes the probability model for a satellite to send and not send data in each time slot of space-time graph.Using the Dijkstra algorithm and the probability fusion algorithm to find the minimum cost paths at the allowed congestion probability for the transmitted data.This topic uses Matlab simulation platform to verify the algorithm,and analyzes and compares the performance of the algorithm simulation results.The algorithm in this paper can effectively reduce the transmission cost when accepting a certain congestion probability.Then,for the congestion problem in this algorithm,this paper uses the routing algorithm to find the "bypass" to solve the congestion pro blem in the satellite network.That is,the optimal path is found by "bypassing" some point-to-point links that have a certain probability of being occupied by data transmitted by other sources.The algorithm is verified by Matlab simulation platform,this algorithm can effectively improve the data transmission success probability without affecting the data transmission of other sources.