Method and apparatus for transmitting channel state information in wireless communication system

A method for transmitting a channel state information (CSI) by a user equipment (UE) in a wireless communication system, the method comprising:

• determining a precoding type indicator (PTI) and a precoding matrix indicator (PMI) based on a rank indicator (RI);
• and
• reporting the CSI including the PTI, PMI and the RI to a base station (BS);
• wherein if the RI is greater than 2, the PTI is equal to 1 and the PMI is restricted to use 4 precoding matrices out of 16 precoding matrices in a codebook, and
• wherein the 4 precoding matrices are as follows:
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• .

A user equipment for transmitting a channel state information (CSI) in a wireless communication system, the user equipment comprising:

• a radio frequency (RF) unit;
• and
• a processor operably coupled with the RF unit and configured to:
• determine a precoding type indicator (PTI) and a precoding matrix indicator (PMI) based on a rank indicator (RI);
• and
• report the CSI including the PTI, PMI and the RI to a base station (BS);
• wherein if the RI is greater than 2, the PTI is equal to 1 and the PMI is restricted to use 4 precoding matrices out of 16 precoding matrices in a codebook, and
• wherein the 4 precoding matrices are as follows:
• W
• 0
• =
• 1
• 2
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• [
• 1
• 1
• 1
• 1
• 1
• 1
• -
• 1
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• 1
• 1
• -
• 1
• 1
• -
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• 1
• -
• 1
• -
• 1
• 1
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• .