Multiple-input multiple-output systems and methods for wireless communication thereof for reducing the quantization effect of precoding operations utilizing finite codebooks

A method for wireless communication in a multiple-input multiple-output (MIMO) system, between a transmitter and a receiver, comprising:

• obtaining downlink channel state information at the receiver side;
• determining a first optimum matrix and a second optimum matrix according to the obtained downlink channel state information at the receiver side;
• selecting a first set of information from a first finite codebook and a second set of information from a second finite codebook according to the obtained downlink channel state information at the receiver side;
• determining first scalar coefficients based on the first set of information at the receiver side, wherein the first scalar coefficients are determined by calculating a projection of the first optimal matrix onto a subspace spanned by the first set of information;
• determining second scalar coefficients based on the second set of information at the receiver side, wherein the second scalar coefficients are determined by calculating a projection of the second optimal matrix onto a subspace spanned by the second set of information;
• transmitting the first set of information, the second set of information, the first scalar coefficients and the second scalar coefficients from the receiver to the transmitter;
• generating a first refined precoding matrix based on the first set of information and the first scalar coefficients and generating a second refined precoding matrix based on the second set of information and the second scalar coefficients at the transmitter side;
• generating a final precoding matrix based on at least the first refined precoding matrix and the second refined precoding matrix at the transmitter side;
• and
• applying the final precoding matrix to precode data signals to be transmitted from the transmitter to the receiver to reduce the quantization effect of precoding operations.