In recent years, an Ultra Wideband (UWB) has attracted much attention in short range high speed wireless communications. Meanwhile, the single-carrier transmission with frequency domain equalization (SC-FDE) has also recently attracted much attention. It is reported that the SC-FDE system obtains an excellent performance as well as orthogonal frequency division multiplexing (OFDM), because the SC-FDE system has the advantage of frequency diversity gain even in strong frequency selective channels. However, in the SC-FDE system, the cyclic extension reduces the bandwidth efficiency. Thus, in the SC-FDE system, various methods to improve the bandwidth efficiency are reported. In this paper, we evaluate the improvement of bandwidth efficiency based on cyclic prefix (CP) reconstruction as a method of improving bandwidth efficiency of Ultra Wideband-Impulse Radio (UWB-IR) and Direct Sequence-Ultra Wideband (DS-UWB).