Complexity Reduction for MC-CDMA With MMSEC

The minimum mean square error combining (MMSEC) scheme performs best among various equalization and combining schemes for downlink multicarrier code-division multiple access (MC-CDMA). However, it is also the most computationally complex to realize as it involves the complex matrix inversion operation of a large matrix. In this paper, a new method is proposed to calculate the equalizer coefficient for MMSEC based on reduced-size matrices. It is shown that as long as the number of users is even, the matrix inversion size is reduced to at least , where is the number of subcarriers.