A New TCP Control Method for Guaranteeing Throughput over High Speed Satellite Links

By launching WINDS (Wideband Inter Networking engineering test and Demonstration Satellite), the speed of satellite link has become larger such as that of terrestrial links. The experiment of ``Super Hi-Vision definition TV" has been studied over WINDS. Thus, it is expected that the use of such multimedia application over the satellite Internet will become larger. It is necessary for such applications to guarantee the throughput. QoS-TCP has been proposed to guarantee throughput by using a transmission control protocol. The traditional QoS-TCPs can obtain the required throughput by adjusting sending rate in response to the demand of application. However, the retransmission control of traditional QoS-TCPs is same as a normal TCP. If these methods are used over the satellite links which have large-bandwidth, long delay and packet losses, it is possible that these methods can not obtain the required throughput when packet losses occur. In this paper, we propose a control method for QoS-TCP, which moderates degradation of congestion window and accelerates the data transmission speed when packet losses occur. As a result, it is expected that the proposal can improve the QoS-TCP performance for guaranteeing the throughput. Simulation results show the proposal can obtain better throughput than the existing method over the typical satellite link which has bit error and coexists the background flows.