Blind channel estimation for multiple access UWB communications based on periodic time hopping and pulse-rate modeling

In an impulse radio based ultra-wideband (UWB) wireless communication system, the transmitted signal propagates through a rich multipath channel. So far, channel estimation has been addressed for a single-user system by a computationally demanding, maximum-likelihood technique. For a multiuser system, a pulse-rate channel input/output vector model is first derived in this paper which exhibits a tri-linear structure with a new-defined input, effective channel and hopping-code dependent matrix for each user. Such a structure can be regarded as similar to a code-division multiple access (CDMA) system. Therefore covariance based blind channel estimation methods successful therein can be applied to estimate UWB channels.