Time-domain multiuser detection for MC-CDMA systems without cyclic prefix

In multicarrier code-division multiple access (MC-CDMA) systems over the finite impulse response (FIR) channel, a usual approach for combating the resultant hostile intersymbol interference (ISI) is via addition of a cyclic prefix (CP) to each transmitted data block. However, ISI is eliminated at the cost of reduction in spectral efficiency. In order to recover spectral efficiency, it is meaningful to investigate MC-CDMA systems without CP. This paper explores the multiuser detection for the MC-CDMA system without CP. We interpret the MC-CDMA system without CP as an equivalently time-domain ISI-corrupted direct sequence (DS-) CDMA system with specific spreading codes. Successively, based on this representation, a time-domain linear minimum mean square error (MMSE) multiuser detection scheme is derived for the MC-CDMA system without CP. Computer simulations illustrate both the validity and the overall performance of the proposed multiuser detection scheme.