A new multiuser detector for CDMA signals over frequency-selective fading channels with narrowband interference

In this paper we derive a new suboptimum multiuser receiver for CDMA signals in the presence of frequency-selective fading and narrowband interference. The proposed detector, which can be interpreted as a generalization of the decorrelating detector, achieves interference cancellation by projecting the received signal onto the orthogonal complement of the subspace spanned by the narrowband and multiaccess interference. As to the performance, we consider the case of Rayleigh-fading channel, showing that the new receiver largely outperforms the conventional decorrelating detector, especially in the presence of strong narrowband interferers, at the price of a little additional loss as no narrowband interference is active.