Method and device for transmitting and receiving channel state information in mobile communication system

A method for receiving channel state information by a base station in a mobile communication system, the method comprising:

• transmitting, to a user equipment (UE), a higher layer signaling message comprising information indicating a reporting mode for the channel state information and information related to a codebook subset configuration indicating subsampling a master codebook for use in reporting the channel state information;
• receiving the channel state information comprising a precoding matrix indicator (PMI) from the UE;
• determining whether codebook subsampling has been applied to the master codebook based on the reporting mode and the codebook subset configuration, wherein the master codebook is defined as a set of precoding matrices shared by the UE and the base station;
• upon determining that the codebook subsampling has been applied, generating a subsampled codebook by subsampling the master codebook and identifying a precoding matrix indicated by the PMI based on the subsampled codebook;
• and
• when a plurality of feedback components are permitted to be simultaneously transmitted, determining that the PMI was generated assuming a particular codebook subset configuration which does not require subsampling and that the codebook subset configuration made by the higher layer signaling was neglected by the UE.

A device in a user equipment (UE) for transmitting channel state information in a mobile communication system, the device comprising:

• a transceiver;
• and
• a controller coupled with the transceiver and configured to:
• receive a higher layer signaling message comprising information indicating a reporting mode for the channel state information and information related to a codebook subset configuration indicating subsampling a master codebook for use in reporting the channel state information;
• determine whether to apply codebook subsampling to the master codebook based on the codebook subset configuration and the reporting mode, wherein the master codebook is defined as a set of precoding matrices shared by the UE and a base station;
• upon determining to apply the codebook subsampling to the master codebook, generate a subsampled codebook by subsampling the master codebook and generate the channel state information comprising a first precoding matrix indicator (PMI) indicating a precoding matrix selected from the subsampled codebook;
• when a plurality of feedback components are permitted to be simultaneously transmitted, further generate the channel state information further comprising a second PMI generated by assuming a particular codebook subset configuration which does not require subsampling and neglecting the codebook subset configuration made by the higher layer signaling;
• and
• transmit the channel state information to the base station.

A device in a base station for receiving channel state information in a mobile communication system, the device comprising:

• a transceiver;
• and
• a controller coupled with the transceiver and configured to:
• transmit, to a user equipment (UE), a higher layer signaling message comprising information indicating a reporting mode for the channel state information and information related to a codebook subset configuration indicating subsampling a master codebook for use in reporting the channel state information;
• receive the channel state information comprising a precoding matrix indicator (PMI) from the UE;
• determine whether codebook subsampling has been applied to the master codebook based on the reporting mode and the codebook subset configuration, wherein the master codebook is defined as a set of precoding matrices shared by the UE and the base station;
• upon determining that the codebook subsampling has been applied, generate a subsampled codebook by subsampling the master codebook and identifying a precoding matrix indicated by the PMI based on the subsampled codebook;
• and
• when a plurality of feedback components are permitted to be simultaneously transmitted, determine that the PMI was generated assuming a particular codebook subset configuration which does not require subsampling and that the codebook subset configuration made by the higher layer signaling was neglected by the UE.