A new blind channel estimation technique is proposed for space-time coded wideband CDMA systems using aperiodic and possibly multirate spreading codes.Using a decorrelating front end, the received signal is projected onto a subspace from which channel parameters can be read more estimated up to a rotational ambiguity.Exploiting the subspace structure of the WCDMA signaling and the orthogonality of the unitary space-time codes, the proposed algorithm provides a blind channel estimate fleshlight automatique via least squares.A new identifiability condition is established under the assumption that the system is not heavily loaded.The mean square error of the estimated channel is compared with the Cramér-Rao bound, and the bit error rate (BER) performance of the proposed algorithm is compared with that of differential schemes.