Research On Congestion Control Of Satellite Link Transmission Layer

With the rapid development of Internet technology,the types of business and the number of services are also increasing.Traditional ground networks are no longer sufficient to support the huge business volume.Therefore,satellite communication technology will become an important means of information transmission.Satellite communication has the advantages of long transmission distance,wide coverage,high communication scalability,wide communication frequency band,and no geographical restrictions.These characteristics of satellite networks enable wireless communication to have more room for development.However,satellite networks are significantly different from traditional terrestrial networks.The characteristics of long data round-trip intervals,high bit error rates,and two-way link asymmetry make terrestrial transmission control protocols not well adapted to satellite communications.In response to the above problems,many domestic and foreign experts and research scholars have conducted in-depth research and improvement on the TCP congestion control model,so that the TCP protocol can overcome the disadvantages of the satellite network while maintaining its own advantages.This article first introduced the working principle of the transmission control protocol and analyzed the characteristics of the satellite link.Combining these two factors,it is concluded that when the TCP protocol is affected by the satellite link,it will cause the original congestion control algorithm to be unable to accurately determine the congestion,making the congestion window more volatile and reducing link bandwidth utilization.To solve the above problems,the original TCP Vegas algorithm is improved,and a Vegas?S congestion control algorithm that can actively adapt to link changes is proposed.The Vegas?S algorithm mainly adjusts the working mechanism of TCP from three perspectives.First of all,add a new RTT calculation method to replace the original RTT calculation method,and solve the problem of unfair RTT calculation caused by the original Vegas algorithm due to link asymmetry.The improved RTT calculation method can calculate more accurately The effective time delay in the link makes the judgment of congestion in the network more accurate.Secondly,Vegas?S algorithm also provides a solution to a series of problems caused by too long satellite round-trip delay.The main content is to add a new congestion window growth strategy and parameter variables during the slow start phase,which solves the bandwidth utilization during short connections.At the same time,it also avoids the sudden congestion caused by the excessive window increase in the late stage of slow start.Finally,improvements were made in the congestion avoidance stage,adding a bandwidth discrimination mechanism,predicting the network status more accurately,adjusting the transmission rate reasonably,and increasing the stability and efficiency of the algorithm.Choose OPNET software as the simulation tool,and build a simulation model with reference to the actual satellite network environment.Through the comparative analysis of Vegas algorithm and the new algorithm under different network parameters,it is verified that the new algorithm is more suitable for data transmission control in the satellite environment.It improves the transmission stability while maintaining a higher throughput level.