A low complexity approach of chip-level MMSE equalization

This paper focuses on the downlink in a CDMA based multi-user communication system experiencing frequency dependent multi-path fading. If the spreading codes are orthogonal and the channel is frequency-flat, the traditional Rake receiver is optimal. However, frequency-selective fading channels destroy the orthogonality of the spreading codes and the chip-level equalizer is proved effectively to restore the orthogonality[1]. For further improvement, the best delay is chosen to minimize the MSE. In order to reduce the computational complexity of the chip equalizer, this paper presents a novel block iterative LMMSE(B_LMMSE) algorithm. Simulations are carried in time-varying frequency-selective fading environment and show that prosed algorithm achieve great performances.