Analysis and Improvement of Fairness among TCP Connections transmitting Differently Sized Data

Short-lived TCP connections, which transmit small-sized data, suffer from significant low throughput compared with long-lived TCP connections, which transmit large-sized data, because of the inherent nature of the ACK-based window flow control of TCP. In this paper, we focus on the unfairness problem caused by transmitting differently sized data. We first confirm the unfairness property through simple simulation results, and show the necessity of devising a method to improve the fairness property at the router buffer. As preparation for realizing this method, we next introduce a new analysis approach to estimate the throughput of a TCP connection when the packet loss probabilities of each transmitted packet are different. Our analysis gives a better estimation of the TCP throughput than the existing analyses. Using the analysis results, we propose a new method to improve the fairness property, and show that our proposed method can improve the fairness property without degradation of the network link utilization.