TCP-FIT: An Improved TCP Algorithm for Heterogeneous Networks

Wireless networks and large bandwidth delay product (BDP) networks are two types of challenging environments for TCP congestion control. Many congestion control algorithms have been proposed to improve the performance of TCPs in these two environments. Although these improved algorithms can achieve remarkable performance enhancements for either of the two environments, designing a congestion algorithm that performs well over heterogeneous networks that contain both wireless and large BDP links remains a great challenge. In this study, we propose a novel congestion avoidance algorithm called TCP-FIT, which can perform excellently over both wireless and large BDP links while maintaining good fairness with the standard TCP Reno algorithm. To evaluate the proposed algorithm, theoretical analysis is presented for equilibrium, network utilization, stability, TCP friendliness, RTT fairness, and responsiveness. A series of experimental results obtained using network emulators and over the “live” Internet are also presented to demonstrate the significant performance and fairness improvements of TCP-FIT compared with other state-of-the-art algorithms.