A Dynamic Splitting TCP Using both Packet Loss Rate and Latency

Advancements in wireless communication technology have led to the increased use of high-latency, high-packet loss links, such as satellite connections in communication paths. Conventional Transmission Control Protocol (TCP), based on the end-to-end principle, experiences significant throughput degradation in such environments owing to inefficient retransmission control. High propagation latency further exacerbates throughput degradation. To solve this problem, splitting TCP connections at a relay device has been proposed to reduce retransmission latency, making it effective to split connections immediately after high-loss links. However, conventional approaches use fixed splitting devices, which are not always positioned immediately beyond high-loss links. In this study, we propose an adaptive TCP connection-splitting method, called TCP-DOPPEL+ (TCP-Dynamically Opt for Proxy to achieve performance enhancement based on Link-state PLUS), for network environments where heterogeneous communication links are mixed on a route. The proposed method calculates an expected value based on the packet loss rate and latency on the link, dynamically adjusting the TCP connection splitting devices accordingly. Evaluation in a virtual network environment confirmed that the proposed approach improves throughput compared to conventional methods.