Channel estimation and synchronization are crucial problems in coherent ultra wideband (UWB) receiver designs. A joint maximum-likelihood (ML) and minimum-mean-square-error (MMSE) channel esti- mation scheme was developed for more precise channel estimates based on the assumption of exponential multipath decay. The performance improvement was analyzed theoretically with a computer simulation us- ing IEEE 802.15.3a ultra-wideband channel models. Theoretical and simulation results show that the scheme further improves the estimation performance of channel gains and multipath delays compared with the traditional ML channel estimator. Channel estimation and synchronization are crucial problems in coherent ultra wideband (UWB) receiver designs. A joint maximum-likelihood (ML) and minimum-mean-square-error (MMSE) channel esti- mation scheme was developed for more precise channel estimates based on the assumption of exponential multipath decay. The performance improvement was analyzed theoretically with a computer simulation us- ing IEEE 802.15.3a ultra-wideband channel models. Theoretical and simulation results show that the scheme further improves the estimation performance of channel gains and multipath-seeings with the traditional ML channel estimator.