Apparatus and method for beamforming for downlink data transmission in wireless communication system

A method performed by a base station supporting a beam forming in a wireless communication system, the method comprising:

• generating configuration information on channel state information (CSI) including parameters of a code book and a parameter (NDFT) indicative of a maximum number of discrete Fourier transform (DFT) vectors with one signal polarization in a precoding matrix and information for a power normalizing the precoding matrix;
• transmitting, to a user equipment (UE), the configuration information on the CSI;
• transmitting, to the UE, CSI reference signals (CSI-RSs);
• receiving, from the UE, CSI including at least one of a rank indicator (RI) of a chosen number L of multiple input and multiple output (MIMO) layers, and a precoding matrix indicator (PMI);
• determining normalization parameters for the generated precoding matrix based on normalizing information, wherein the determined normalization parameters include a common normalization parameter applied to the precoding matrix as a whole and an individual normalization parameter respectively applied to individual precoding vectors or groups of precoding vectors of the precoding matrix;
• and
• applying the determined normalization parameters to the generated precoding matrix.

A user equipment (UE) supporting a beam forming in a wireless communication system, the UE comprising:

• a transceiver;
• and
• a controller coupled with the transceiver, and configured to:
• receive, from a base station, configuration information on channel state information (CSI) including parameters of a code book and a parameter (NDFT) indicative of a maximum number of discrete Fourier transform (DFT) vectors with one signal polarization in a precoding matrix,
• receive, from the base station, CSI reference signals (CSI-RSs),
• choose a number (L) of MIMO layers,
• based on the parameters of the code book, the parameter indicative of the maximum number of DFT vectors and the number (L) of MIMO layers, generate the precoding matrix including precoding vectors, wherein a number of the precoding vectors is same as the number (L) of the MIMO layers, and
• based on the received CSI-RSs, transmit, to the base station, CSI including at least one of a rank indicator (RI) of a chosen number L of multiple input and multiple output (MIMO) layers, and a precoding matrix indicator (PMI).

A base station supporting a beam forming in a wireless communication system, the base station comprising:

• a transceiver;
• and
• a controller configured to:
• generate configuration information on channel state information (CSI) including parameters of a code book and a parameter (NDFT) indicative of a maximum number of discrete Fourier transform (DFT) vectors with one signal polarization in a precoding matrix and information for a power normalizing the precoding matrix,
• transmit, to a user equipment (UE), the configuration information on the CSI,
• transmit, to the UE, CSI reference signals (CSI-RSs),
• receive, from the UE, CSI including at least one of a rank indicator (RI) of a chosen number L of multiple input and multiple output (MIMO) layers, and a precoding matrix indicator (PMI),
• determine normalization parameters for the generated precoding matrix based on normalizing information, wherein the determined normalization parameters include a common normalization parameter applied to the precoding matrix as a whole and an individual normalization parameter respectively applied to individual precoding vectors or groups of precoding vectors of the precoding matrix, and
• apply the determined normalization parameters to the generated precoding matrix.