Enhanced Westwood as per Vegas-Based Estimator with Slowstart Threshold for High-Speed Networks

With the growth of the mobile communication technology and the establishment of broadband networks, a transport layer protocol that is suitable for these circumstances is required. Although TCP, developed in wired environments, is a generally used transport layer protocol, it is not appropriate for wireless environments that are error-prone and have high delays. Moreover, previous wired and wireless TCP do not utilize the bandwidth efficiently in high-speed networks. The reason for the fact is that those TCP do not consider much lager congestion window size (cwnd) that is possibly obtained from high-speed networks. Therefore, we propose WestwoodVEST (Westwood as per Vegas-based Estimator with Slowstart Threshold), which modifies WestwoodVT and improves performance by utilizing optimized bandwidth in high-speed networks. In this scheme, when packet loss occurs, sender discriminates the cause of packet loss and investigates slowstart threshold (ssthreshold) variation forevery case to anticipate and reflect network condition into the senderpsilas transmission rate. We simulate WestwoodVEST on NS-2 to evaluate the performance, and the result shows that the performance improves by up to 20% with WestwoodVT and 60% with Westwood when the error rate is 1%. Moreover, it also reveals better performance up to 50% with WestwoodVT and over 300% with Westwood when the error rate is between 5% and 10%. These results demonstrate the superiority of WestwoodVEST not only in wireless environments, but also in high-speed network environments.