An adaptive parallel interference canceler using adaptive blind arrays

The performance of code-division multiple access (CDMA) receivers can be significantly enhanced by employing multiuser detection techniques and antenna arrays. A compromise between the system performance and the computational complexity is obtained by employing parallel interference cancellation due to its simple structure. We propose a technique in which an adaptive parallel interference canceler (APIC) and adaptive blind arrays are combined. The blind algorithm is formulated using a constrained optimization criterion, and the adaptation is carried out using LMS algorithm combined with the gradient-projection algorithm to incorporate the quadratic constraint. Simulation results are presented to show the excellent performance of the proposed structure in comparison with that of using either multiuser detection or smart antennas in a severe near-far situation.