Block spectral precoding for blind multiuser detection of DS/CDMA signals

A new approach for blind multiuser detection of DS/CDMA signals is proposed. This approach is based on modifying the data power spectrum, uniquely for each user, through a two-stage colouring-whitening precoding scheme. This enables detection of a desired user´s signal in an unknown multipath channel, regardless of the power of the interferers. The proposed precoding method does not alter the data rate or system bandwidth. Detection does not require spreading code knowledge, and consequently avoids channel estimation and the possible associated errors. The method is seen to yield reasonable performance besides being able to operate properly in nearly saturated systems, in contrast to some existing methods. Besides this, it can tolerate severe carrier frequency offsets.