To adapt to the dynamic and variable network environment of the 5th Generation Mobile Communication System-Railway,and to address issues such as decreased throughput,increased transmission delay,and difficulty in ensuring the reliability of detection data transmission between train and ground,this paper analyzes the transmission control protocol(TCP)congestion control process and compares the existing problems with three basic congestion control algorithms:TCP-Reno,TCP-Vegas,and TCP-Westwood.Based on this analysis,a congestion control algorithm that combines transmission time interval(TTI)and round-trip time(RTT)called the TTI-RTT algorithm is proposed.This algorithm calculates the test statistic for pairwise comparison and the current network congestion factor based on the RTT measurement value,using both as a criterion for judging network congestion.It dynamically adjusts the additive and multiplicative factors based on the congestion factor reflecting the degree of network congestion.Additionally,the transmission time interval is flexibly adjusted during different conditions of congestion control.Using the NS-3 simulation software,a point-to-point communication network topology is constructed considering the error code impact of high-speed railway 5G-R wireless channel,the TTI-RTT congestion control algorithm is validated through simulation and compared with the three basic algorithms in terms of performance.The results show that under different packet loss rates,the average throughput of the proposed algorithm remains above 9 Mb·s-1,which is an increase of about 5.9％over the highest and most stable throughput of the basic TCP-Reno algorithm,with significant improvements in real-time throughput stability.
维普
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