Patent ID: 8861639

Claim:
A method for determining precoding matrix for the sub-band precoding in a transmitter, wherein the transmitter has M transmitting antennas, and the method comprises: determining an optimized first matrix W 1 according to wideband and/or long-term channel properties, with the first matrix W 1 corresponding to wideband and/or long-term channel properties; multiplying the optimized first matrix W 1 with a second matrix W 2 in a second codebook, so as to obtain a plurality of candidate precoding matrices, with the second matrix W 2 corresponding to frequency-selective and/or short-term channel properties; selecting an optimized one from the plurality of candidate precoding matrices for precoding the data to be transmitted, according to a frequency selection and/or a short-term channel state information; wherein, the amount of discrete Fourier transform (DFT) beams is increased to improve the spatial resolution; a diagonal matrix is involved in said first matrix W 1 ; and phase adjustment is involved in said second matrix W 2 , so as to guarantee the adjusted phase is evenly distributed among the whole phase space.