A least-square unconstrained frequency-domain adaptive filter approach for chip-level equalization of DS-CDMA systems

In this paper, we propose a modified least-square unconstrained frequency-domain block adaptive filter for chip-level equalization of the downlink of a DS-CDMA system. The modification allows us to refine the equalizer coefficients and improve the convergence and tracking by reducing the misadjustment error. We also analyze the impact of the wrap-around effect that is introduced by the circular convolution. Such analysis takes into account the position of the FFT window, the channel´s phase, the signal-to-noise ratio per bit and the system load.