Two-stage hybrid decision feedback equalization for DS-CDMA systems

This letter proposes a hybrid decision-feedback equalizer (HDFE) for DS-CDMA systems. The proposed HDFE is carried out in two stages to improve the accuracy of the feedback signals by exploiting the spreading gain in the feedback filter. The spread signals for a symbol are buffered and then detected, after which re-spreading is applied to generate feedback signals at the chip level. Through the use of symbol detection for feedback filtering, more accurate feedback signals are achieved. Simulation results demonstrate the superior error performance of the proposed scheme over the frequency domain linear equalization (FD-LE) and RAKE schemes in highly dispersive channels.