Dynamic parameter adjustment for available-bandwidth estimation of TCP in wired wireless networks

With the extensive spread of the Internet and mobile terminals, the Internet access from a mobile terminal becomes more important than ever before. In the Internet, Transmission Control Protocol (TCP) is used as a standard data transport protocol, however, it is well known that TCP performance degrades in wired-wireless network environments. This is because TCP is designed originally for wired network environment. In this paper, we propose a simple TCP algorithm for wired-wireless network environment focusing on small-sized file documents transmission. In the proposed algorithm, available bandwidth of network is well estimated with time intervals between consecutive ACKs. With the estimates, the congestion control in the proposed method adapts to the state of wireless link and prevents throughput degradation. A simple filter is used for available bandwidth estimation and dynamic adjusting of filter parameter according to the state of wireless link improves the throughput of small-sized file transmission. We compare the proposed algorithm with existing TCP Reno and TCP Westwood by simulation and show that the proposed algorithm achieves better performance than existing two TCP algorithms in wired-wireless network environment.