MMSE combining scheme with subblock noise covariance matrix for fractional sampling-OFDM receivers

A diversity scheme with fractional sampling (FS) in OFDM receivers is investigated recently. When a sharp filter is employed, the correlation of noise samples among the adjacent subcarriers increases, and the performance of this scheme is deteriorated. Therefore, low-complexity subcarrier based MMSE combining scheme with the subblock of the noise covariance matrix is proposed in this paper. Numerical results through computer simulation show that the MMSE combining scheme proposed in this paper can outperforms a conventional MRC scheme and a subcarrier based MMSE combining scheme, when the sharp filter is employed.