Low complexity CDMA downlink receiver based on frequency domain equalization

This paper proposes a new approach to apply frequency domain equalization (FDE) in the downlink of broadband CDMA cellular systems. Equalization has been recognized as a better receiving method than the RAKE receiver for CDMA downlink systems, especially in cells with a high number of users. By performing the equalization in the frequency domain, the complexity of the equalization algorithm can be significantly reduced with the help of the FFT operation. Three methods of implementing FDE in the CDMA downlink are described: the cyclic prefix method, the zero padding method, and the overlap-cut method. In addition to its simplicity and good performance, the FDE also offers the possibility to build a multimode receiver for singlecarrier and multicarrier signals. Simulation results are presented in a TD-CDMA system with parameters taken from the UTRA-TDD standard.