A blind interference canceller in DS-CDMA

We propose a new interference cancellation scheme for the downlink CDMA where only the signature of the user of interest is known. The spreading sequences of the interfering users can be estimated by exploiting their constant modulus property. We consider first a single-path synchronous CDMA system and propose a Jacobi-like blind algorithm to estimate the unknown signatures. The latter are used first to estimate a set of subspace-based MMSE detectors of the interfering users and then to perform parallel or sequential interference cancellation. Finally we show how the previous results can be generalized to the multipath case