Ultra-wideband (UWB) communication is a promising technology to provide high data rates with low power consumption in wireless personal area networks. Among the standards adopting the UWB technology, Wireless USB (WUSB) running on the platform of WiMedia aims to provide high-speed wireless connectivity between mobile devices. To support reliable connectivity, data rates should be adapted according to UWB channel states that are time- varying. In this paper, we propose a novel rate adaptation scheme which considers the characteristics of WUSB protocol as well as the time-varying UWB channel. Our proposed scheme uses the channel prediction in a short time scale. Specifically, the channel state of the previous time window is used to determine the data rate of the next time window, assuming the channel similarity between the two successive time windows. Through extensive trace-driven simulations, we show that the proposed rate adaptation scheme outperforms the conventional schemes.