On the identifiability of multipath parameters

Consider a received signal consisting of noise and an unknown waveform that arrives at a sensor through both a direct path and an attenuated and delay ed specular path. We show that a commonly used frequency-domain model for s uch a signal is valid essentially only under the assumption that the wavefo rm that underwent multipath propagation is band-limited. Furthermore, we de rive sufficient conditions for the aforementioned model to be identifiable from second-order statistics (i.e., its parameters can be uniquely determin ed from the spectral density of the received signal). We also show that in the frequently considered case of a white waveform, neither the attenuation coefficient, nor the waveform power, nor the noise power can be unambiguou sly determined. (C) 1999 Elsevier Science B.V. All rights reserved.