Abstract: A novel M-ary MC-CDMA system in uplink TDD mode is proposed based on orthogonal cyclic codes and pre-equalization. At the transmitter, every mobile user uses the orthogonal cyclic codes as spreading codes, which reduces the spreading codes selection difficulty of the M-ary MC-CDMA system. In order to keep a good orthogonal characteristic among all users’ signals, a pre-equalizer is employed to process the M-ary MC-CDMA signal before being transmitted. The received signal is multiplied by the local sequence, and then the proposed scheme achieves the M-ary despread spectrum and OFDM demodulation at the same time. The results show that the proposed scheme has better bandwidth efficiency and lower computation complexity than traditional M-ary MC-CDMA systems.

Key words: MC-CDMA, M-ary spread spectrum, orthogonal cyclic codes, pre-equalization