WCSE

An Improved Slow-start and Congestion Avoidance Algorithm based on TCP Westwood

Abstract— TCP Westwood (TCPW) utilizes the estimated link available bandwidth by measuring and averaging the rate of returning ACKs to appropriately set the slow start threshold (ssthresh) parameters, and performs well in wired/wireless networks. However, TCPW still obeys the rules of exponential and linear increment of the traditional TCP Reno and cannot adaptively adjust the congestion window (cwnd) depending on the network status during the slow-start and congestion avoidance phase, leading to more packets losses, frequent retransmissions and lower bandwidth utilization. In view of the above problems, this paper presents an improved algorithm TCPW RB, the algorithm in the slow-start and congestion avoidance phase, respectively, utilizing the buffer queue length and the bandwidth ratio factor to adaptively adjust the increments of cwnd. Simulation results show that the proposed algorithm can effectively reduce the packet losses, improve the bandwidth utilization and throughput with good fairness and friendliness.

Index Terms— slow-start, congestion avoidance, TCPW, bandwidth ratio.

Hong Jie, Rui-Qing Wu, Nan Ding
School of Electronic Engineering, University of Electronic Science and Technology of China, CHINA

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Cite: Hong Jie, Rui-Qing Wu, Nan Ding, "An Improved Slow-start and Congestion Avoidance Algorithm based on TCP Westwood," 2015 The 5th International Workshop on Computer Science and Engineering-Information Processing and Control Engineering (WCSE 2015-IPCE), pp. 668-674, Moscow, Russia, April 15-17, 2015.