Improve TCP Westwood with CAPPROBE Bandwidth Estimation

Traditional TCP protocols regard all packet losses as the signals of network congestions in wireless networks,and then immediately decrease Congestion Window(cwnd)which results in the unnecessary degradation of transmission.For purpose of solving this problem,TCP Westwood(TCPW)monitors the stream of acknowledges(ACKs)for obtaining more information to estimate the bandwidth of links.The bandwidth estimation is then used to adjust the parameters of congestion control algorithms.We introduce a more accurate bandwidth estimation,thus present and implement a new network congestion algorithm TCPW CAPPROBE(TCPWC).TCPWC acquires more accurate bandwidth by designing ACK pairs based on the CAPPROBE algorithm.Then we adjust cwnd and Slow Start Threshold(ssthresh),thus avoid overreaction of congestion control mechanism.The simulation results in Network Simulator ns-3have shown that TCPWC outperforms TCPW and other existing TCP versions such as TCP Tahoe,TCP Reno,and TCP NewReno in terms of network throughput,fairness and friendliness.