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

With the extensive spread of the Internet and mobile terminals, Internet access from a mobile terminal becomes more important than ever before. In the Internet, the 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 was designed originally for an exclusively wired network environment. In this paper, we propose a simple TCP algorithm for wired-wireless network environments by focusing on small-sized file document transmission. In the proposed algorithm, the available bandwidth of a network is well estimated with time intervals between consecutive ACKs. With these estimates, the congestion control in the proposed method adapts to the state of a wireless link and prevents throughput degradation. A simple filter is used for available bandwidth estimation and dynamic adjusting of a filter parameter according to the state of the wireless link, thus improving the throughput of small-sized file transmission. We compare the proposed algorithm with the existing TCP Reno and TCP Westwood by simulation and show that the proposed algorithm achieves better performance than these two TCP algorithms in wired-wireless network environments.