Template design and propagation gain for multipath UWB channels with per-path frequency-dependent distortion

Due to the large bandwidth allocation, Ultra-Wideband (UWB) channels exhibit frequency-dependent distortion of individual multipath components. This per-path distortion is particularly significant in outdoor UWB applications, where line-of-sight (LOS) or non-distorted reflected signals might not be available at the receiver, and the dominant propagation mechanisms involve shadowing (diffraction) or reflection by small objects (e.g. signs or lamp-posts). In this paper, a physical model is employed in the design of robust correlation receiver templates for outdoor single and multipath impulse radio channels characterized by per-path distortion. It is demonstrated that receivers which employ a set of partial derivatives templates are near-optimal in terms of energy capture while the simple transmit pulse template provides excellent complexity-performance trade-offs for most practical scenarios. Moreover, iterative receiver structures that maintain the energy capture in the presence of overlapping multipath components are investigated. Finally, a large gap between the propagation gains of the transmit pulses in the lower and upper bands of the FCC spectrum is characterized for several propagation mechanisms.