Method for determining precoding matrix indicator, user equipment, and base station evolved NodeB

A device, comprising:

• a receiver, configured to receive a reference signal from a base station;
• a processor, configured to determine, based on the reference signal, a precoding matrix from a codebook, wherein a precoding matrix W comprised in the codebook is a product of two matrices W1 and W2, wherein W1 is a block diagonal matrix, W1=diag{X1, . . . , XNB}, wherein each block matrix Xi is a Kronecker product of a matrix Ai and a matrix Bi, Xi=AiBi, 1≤i≤NB, and block matrices in the W1 satisfy that X2j-1=X2j, 1≤j≤NB2;
• and
• a transmitter, configured to send a precoding matrix indicator (PMI) to the base station, wherein the PMI corresponds to the determined precoding matrix.

A non-transitory computer-readable storage medium comprising instructions which, when executed by a computer, cause the computer to:

• receive a reference signal from a base station;
• determine, based on the reference signal, a precoding matrix from a codebook, wherein a precoding matrix W comprised in the codebook is a product of two matrices W1 and W2, wherein W1 is a block diagonal matrix, W1=diag{X1, . . . , XNB}, NB>1, wherein each block matrix Xi is a Kronecker product of a matrix Ai and a matrix Bi, Xi=AiBi, 1≤i≤NB, and block matrices in the W1 satisfy that X2j-1=X2j, 1≤j≤NB/2;
• and
• send, a precoding matrix indicator (PMI) to the base station, wherein the PMI corresponds to the determined precoding matrix.