This article develops a discrete time dynamic feedback model of a congestion control system for a simple network with TCP Westwood （TCPW） connections and a single bottleneck link with random early detection （RED） ...This article develops a discrete time dynamic feedback model of a congestion control system for a simple network with TCP Westwood （TCPW） connections and a single bottleneck link with random early detection （RED） gateway. By using this model, the nonlinear dynamics of the TCPW/RED network are analyzed and its parameter sensitivities are studied. It is shown that periodic doubling bifurcation occurs when the RED control parameters or other parameters are varied. By theoretical analysis, the fixed point, the critical value of parameters and the nature of the bifurcation are determined. Moreover, by using bifurcation diagrams and Lyapunov exponent, the result of theoretical analysis is validated and the bifurcation and chaotic phenomena are numerically studied of the congestion control system with TCPW connections and RED gateway.展开更多
The wireless network is limited by the transmission medium,and the transmission process is subject to large interference and jitter.This jitter can cause sporadic loss and is mistaken for congestion by the congestion ...The wireless network is limited by the transmission medium,and the transmission process is subject to large interference and jitter.This jitter can cause sporadic loss and is mistaken for congestion by the congestion control mechanism.The TCP Westwood protocol(referred to as TCPW)is such that it cannot distinguish between congestion loss and wireless jitter loss,which makes the congestion mechanism too sensitive and reduces bandwidth utilization.Based on this,the TCPW protocol is modified based on the estimate of the Round-Trip Time(referred to as RTT)value-called TCPW BR.The algorithm uses the measured smooth RTT value and divides the congestion level according to the weighted average idea to determine congestion loss and wireless jitter loss.The simulation results show that the TCPW BR algorithm enhances the wireless network’s ability to judge congestion and random errors.展开更多
基金supported by the National Natural Science Foundation of China (70571017)the Fund of High School Excellent Young Talents in Anhui Province (2009SQRZ021)
文摘This article develops a discrete time dynamic feedback model of a congestion control system for a simple network with TCP Westwood （TCPW） connections and a single bottleneck link with random early detection （RED） gateway. By using this model, the nonlinear dynamics of the TCPW/RED network are analyzed and its parameter sensitivities are studied. It is shown that periodic doubling bifurcation occurs when the RED control parameters or other parameters are varied. By theoretical analysis, the fixed point, the critical value of parameters and the nature of the bifurcation are determined. Moreover, by using bifurcation diagrams and Lyapunov exponent, the result of theoretical analysis is validated and the bifurcation and chaotic phenomena are numerically studied of the congestion control system with TCPW connections and RED gateway.
基金国家自然科学基金(the National Natural Science Foundation of China under Grant No.70571017)广西自然科学基金(the Natural Sci-ence Foundation of Guangxi Chuang Autonomous Region of China under Grant No.0728099)
基金The paper is funded by Guangdong Provincial Department of Education major scientific innovation project characteristics(natural sciences),project number:2014KTSCX210。
文摘The wireless network is limited by the transmission medium,and the transmission process is subject to large interference and jitter.This jitter can cause sporadic loss and is mistaken for congestion by the congestion control mechanism.The TCP Westwood protocol(referred to as TCPW)is such that it cannot distinguish between congestion loss and wireless jitter loss,which makes the congestion mechanism too sensitive and reduces bandwidth utilization.Based on this,the TCPW protocol is modified based on the estimate of the Round-Trip Time(referred to as RTT)value-called TCPW BR.The algorithm uses the measured smooth RTT value and divides the congestion level according to the weighted average idea to determine congestion loss and wireless jitter loss.The simulation results show that the TCPW BR algorithm enhances the wireless network’s ability to judge congestion and random errors.
