Blind channel estimation for MIMO MC-CDMA with arbitrary numbers of antennas and users

A subspace blind channel estimation scheme is proposed for multicarrier(MC)-CDMA systems using multiple antennas. To obtain noise subspace that is essential for subspace blind channel estimation, frequency-domain over-sampling (FDO) is employed at the receiver side. A unique feature of this scheme is that it is applicable to general MC-CDMA systems without any constraint on the numbers of antennas and users. In particular, it can be applied in two challenging situations, for which existing schemes fail: (1) the number of transmit antennas is larger than the number of receive antennas; (2) the number of users is larger than the processing gain. In other cases, the proposed scheme also compare favorably with other existing schemes.