I. Introduction
ULTRA-wideband (UWB) radio transmission has attracted much attention since its allocation of an unlicensed frequency band by the US Federal Communications Commission (FCC) in 2002 [1]. This wide but extremely power limited bandwidth, mainly from 3.1 to 10.6 GHz, allows very high data rate communications for close range applications, such as, wireless personal area network (WPAN) devices and cable replacement. UWB systems are highly power-limited compared to other conventional (narrowband) systems due to the FCC power spectral mask. Pulse shaping techniques that eke out the greatest legally-allowed transmission power are critical to enhancing UWB performance.