Efficient multi-user detection scheme for overloaded group-orthogonal MC-CDMA systems

An efficient multi-user detection scheme for overloaded MC-CDMA systems is presented. The proposed detection scheme for overloaded systems achieves the optimal performance for constant-modulus modulation schemes, for example MPSK, and provides near-optimal performance for non-constant-modulus modulation, for example M-QAM. Moreover, it has overall lower complexity than the other optimal detection algorithms, especially suitable for group-orthogonal MC-CDMA systems, where group-based technique keeps multi-user receiver size relatively small.