Abstract:

Because the satellite communication network link is unstable， the satellite beam has the jumping characteristic. In order to ensure the continuity of communication， the user terminal sharing the same channel needs to switch between different satellites， and the link between the new satellite and the ground station and the user terminal needs to be re-established and adjusted， which leads to the delay mutation problem. However， when the delay increases suddenly， the sending window is reduced too conservatively， which makes the round-trip delay balance in congestion control poor. Therefore， a multi-modal dynamic congestion control algorithm for satellite communication based on link state is proposed. By improving the traditional TCPVegas algorithm， the length of the satellite link is calculated， the round-trip delay is corrected according to the length of the satellite link， and the change of the congestion window caused by the sudden change of the round-trip time is solved. The bandwidth of satellite transmission is judged， and the problem of blind reduction of the congestion window caused by other algorithms is solved. The multi-mode dynamic congestion control of satellite communication is realized. The experimental results show that the algorithm has maximum data throughput and good round-trip delay balance. After changing α and β parameters， the average throughput of the algorithm will be improved obviously， but there is a certain limit. The algorithm can dynamically adjust the size of the congestion window to adapt to the congestion environment and ensure the smooth flow of satellite communication.

Key words: link state, satellite communications, congestion control, dynamic control, TCPVegas algorithm, multi-modal