Multiuser detection using CMA and the cancellation method in fast-fading channels

In this paper, we introduce a modified interference cancellation scheme for multi-user detection in DS/CDMA. Among ICs (interference cancellers), PIC (parallel interference canceller) requires more stages to have a better BER (bit error rate), and SIC (successive interference canceller) faces the problems of power reordering and large delays. Most of all, the adaptive detector achieves good performance using the adaptive filter conducted iteration algorithm. But it requires many iterations for convergence. To resolve those problems, we propose a new hybrid interference cancellation scheme combining the adaptive filter using CMA (constant modulus algorithm) and the cancellation method. The proposed interference canceller improves the performance more than the conventional adaptive detector for the same iterations and completely reduces iterations for the same BER performance because it uses the cancellation method after the process of the adaptive filter. The proposed IC structure does extract the following characteristics.; (1) it has the same BER performance only using much smaller iterations than the conventional adaptive detector (2) the detector having the adaptive filter requires less complexity than a nonlinear detector.