Research On Optimization Of TCP Congestion Control Algorithm In Wireless Network

The ubiquitous mobile Internet facilitates people's lives greatly such as online payment or living video streaming.As the number of users growing,researchers put their focus on how to make the transport layer protocol adapted to the wireless link better.TCP(Transmission Control Protocol)is the most widely used transport layer protocol in the Internet.The classic TCP works well at low speed in wired networks.However in wireless networks,there are some inevitable problems in transport layer such as unstable round trip time and random packet loss due to bit error.These problem makes TCP's performance degraded severely.In this paper,a new TCP congestion control algorithm called TCP WR(TCP Window Retune)is proposed.TCP WR consists of two parts,packet loss detection and congestion window updating.Packet loss detection extracts information from transport layer such as round trip delay to distinguish wireless errors from network congestion.It ensures that TCP sender deal with packet loss more wisely.And congestion window updating is based on bandwidth estimation.With an updating timer,TCP sender triggers window resetting periodically.This mechanism guarantees that the sending rate follows the variation of network bandwidth precisely.To evaluate the performance of proposed algorithm,a transport layer simulation platform is designed and implemented.It provides a full protocol stack environment,factors from physic layer to application layer can be configured.According to the simulation in the end-to-end link,this paper analyses the congestion window of TCP New Reno,TCP Vegas and TCP Westwood to point out the problem of traditional TCP algorithm.Then TCP WR is deployed in a classic LTE(Long Term Evolution)scenario.The results shows TCP WR improves the throughput by 8%-13%compared with TCP New Reno and TCP Westwood.