receiving one or more precoding matrix indicator (PMI) signals from a remote transceiver; and
generating a precoding matrix W equal to a matrix multiplication of two matrices W1 and W2, where said precoding matrix W is applicable to precoding one or more layers of data streams, matrix W1 selected from a first codebook C1 based on a first group of bits in the PMI signals, and matrix W2 selected from a second codebook C2 based on a second group of bits in the PMI signals, wherein the first codebook C1 comprises the following W1 matrices:
Nt≥4 is the number of transmit antennas corresponding to W,
N is an integer number greater than or equal to Nr.