Phase effects in wireless multipath parameter estimation

Though estimating the delays and the amplitudes in wireless multipath channel models free of Doppler and phase differences is well understood and well documented, this is not true for the case when Doppler and phase are included in the model. Phase differences between multipath reflections come from properties inherent to every multipath channel and they produce problems in previously introduced multipath parameter (delay, Doppler 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 in coherent communication systems, if multipath components are to be eliminated, or recombined with the strongest incoming component. 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.