A Simulation-Based Study on Spurious Timeouts and Fast Retransmits of TCP in Wireless Networks

When TCP operates in wireless networks, its congestion control algorithms such as fast retransmit recovery (FRR) and retransmission timeouts (RTO) are often triggered even when there is no congestion. Although such falsely triggered FRRs and RTOs incur sharp performance degradation of TCP, there is little study on problems of spurious FRRs as well as spurious RTOs triggered by various reasons such as sudden delay, wireless transmission errors, and mobility. In this paper, we investigate spurious RTOs and spurious FRRs triggered by different causes, and observe if TCP works as it is originally designed under various network environments. Our work is meaningful in the point of view that it emphasizes the problem of spurious FRRs as well as spurious RTOs which are overlooked in previous works, and the result is informative to design new TCP variants for wireless and hybrid networks.