Clustered channel estimation for UWB signals

Channel estimation for ultra-wideband (UWB) signals is considered herein. The UWB propagation study and associated channel modelling of R. J. -M Cramer et al., (May 2002) suggest clustering occurs in both space and time for indoor wireless office/laboratory environments. Motivated by this study, a two-stage channel estimation scheme is proposed. First, coarse channel estimation is conducted to estimate the nominal location and dispersion of a cluster. Then, channel estimation efforts are concentrated around the nominal parameters to reduce the dimensionality of the estimation of the parameters associated with the different multipath components. Different strategies based on maximum-likelihood, least squares and expectation maximization are presented and compared in terms of estimation accuracy and complexity. The bit error rate of a Rake type receiver is simulated with the estimated channel parameters for a clustered multipath scenario.