Abstract:

This paper presents an overview of UWB propagation channels. It first demonstrates how the frequency selectivity of propagation processes causes fundamental differences between UWB channels and "conventional" (narrowband) channels. The concept of pathloss has to be modified, and well-known WSSUS model is not applicable anymore. Next, describe deterministic and stochastic models for UWB channels and identify the key parameters for the description of delay dispersion, attenuation, and directional characterization, and we survey the typical values that have been measured. We also discuss measurement techniques, and methods for extracting model parameters showing that the concepts of narrowband channel parameter estimation (e.g., maximum-likelihood estimation) have to be modified. Finally we discuss the impact of channel models on various UWB systems.