Decision feedback equalizer for CDMA system with low spreading factor

For wideband code-division multiple access (CDMA) systems, we investigate a decision feedback equalizer (DFE) to effectively suppress serious inter-path interference (IPI) when the spreading factor is low. In order to eliminate the error propagation in DFE, a soft decision feedback equalization structure is also studied. The optimized time delay parameter and unbiased estimator are obtained to further improve the DFE performance. The proposed symbol-level DFE has the same performance as compared to chip-level DFE but it has lower complexity and its adaptive realization can further lower the complexity. The result of simulation and analysis show that the performance of the proposed DFE is better than that of linear MMSE equalizer and standard RAKE receiver.