Large system analysis of blind multiuser detection in CDMA networks

We consider wideband CDMA networks with many users, and study the system performance when blind linear multiuser receivers are employed for demodulation. We first characterize the signal-to-interference-plus-noise ratio (SINR) for blind multiuser receivers. Our results reveal that the SIR of these blind receivers saturates when the power of the desired user increases, which is in stark contrast to the fact that the SIR achieved by the exact MMSE receiver can get arbitrarily large. This saturation phenomenon of SINR indicates that the capacity of a wireless network with blind multiuser receivers is not only interference-limited, but also estimation-error limited. Furthermore, the effect of estimation error can be quantified. We then show that the residual interference at the output of these blind receivers is asymptotically Gaussian. The Gaussianity enables easy characterization of bit error probability. A parallel result is that the estimation error of the receiver is asymptotically orthogonal to the signal space.