A Decision Feedback CP-Assisted CDMA Scheme Using Despreading before Equalization

We study a cyclic prefix (CP) assisted method used for the uplink of code division multiple access (CDMA) systems in which the code despreading is performed in front of the frequency domain equalizer (FDE). The main advantage of the new despreading scheme is that the required points of discrete Fourier transform in the FDE are significantly reduced compared to the conventional CDMA scheme. Although the CDMA system can enhance system capacity as the number of users increases, the multiuser interference (MUI) needs to be mitigated. In our work, an iterative MUI cancellation method in a combination of decision feedback equalization is proposed. Simulation results show that the proposed scheme achieves the similar performance to the conventional CP-CDMA system and the iterative MUI cancellation method essentially eliminates most of MUI with only a couple of iterations.