Performance and analysis of adaptive modulation in MC-CDMA systems

To satisfy the requirement for high data rate and high frequency efficiency in the future mobile radio communication systems, a MC-CDMA system using adaptive modulation is proposed in this paper in order both to achieve frequency diversity effect and to maximize the spectral efficiency in this paper. We also give a practical adaptive modulation algorithm with low computational complexity and small signaling overhead, which is suitable for MC-CDMA downlink transmission. The simulation results show the adaptive MC-CDMA systems outperform conventional MC-CDMA systems. Furthermore, the combining schemes at the receiver in MC-CDMA systems, which affect the efficiency of adaptive modulation algorithm, are also analyzed including the multi-user interference.