The issue of phase in specular multipath parameter estimation

Phase differences between multipath reflections come from properties inherent to every multipath channel and they produce problems in previously introduced multipath parameter (delay, Doppler shift and amplitude) estimators. Ways of overcoming these problems are suggested, and the phase is considered as a parameter to be estimated, as well. Phase estimates are important if multipath components are to be eliminated, or recombined with the direct signal. Cramer-Rao bounds for the estimates of one-path channel parameters (with and without phase) are derived, and final expressions are discussed in light of the influence of phase.