User equipment apparatus and method for feeding back channel state information in a wireless communication system

A user equipment (UE) for transmitting a Channel State Information (CSI) reporting in a wireless communication system, the UE comprising:

• a transmitter;
• and
• a processor operably coupled to the transmitter, the processor configured to:
• control the transmitter to transmit a rank indicator (RI) with a first type precoding matrix indicator (PMI) to a base station (BS) according to a first CSI feedback type,
• wherein the first CSI feedback type is defined when a reporting period of the RI is same as that of the first type PMI, and
• calculate a second type PMI based on a latest RI,
• control the transmitter to transmit the second type PMI with channel quality information (CQI) to the BS according to a second CSI feedback type,
• wherein the RI and the first type PMI are jointly coded, and transmitted through a physical uplink control channel (PUCCH),
• wherein a reporting period of the first CSI feedback type and a reporting period of the second type PMI are defined separately, and
• wherein the reporting period of the first CSI feedback type is equal to or longer than the reporting period of the second type PMI.

A method for receiving a Channel State Information (CSI) reporting by a base station (BS) in a wireless communication system, the method comprising:

• receiving, by the BS from a user equipment (UE), a rank indicator (RI) with a first type precoding matrix indicator (PMI) according to a first CSI feedback type,
• wherein the first CSI feedback type is defined when a reporting period of the RI is same as that of the first type PMI;
• and
• receiving, by the BS from the UE, a second type PMI with channel quality information (CQI) according to a second CSI feedback type, the second type PMI being calculated based on a latest RI,
• wherein the RI and the first type PMI are jointly coded, and received through a physical uplink control channel (PUCCH),
• wherein a reporting period of the first CSI feedback type and the reporting period of the second type PMI are defined separately, and
• wherein the reporting period of the first CSI feedback type is equal to or longer than the reporting period of the second type PMI.

A base station (BS) for receiving a Channel State Information (CSI) reporting in a wireless communication system, the BS comprising:

• a receiver;
• and
• a processor operably coupled to the receiver, the processor configured to:
• control the receiver to receive a rank indicator (RI) with a first type precoding matrix indicator (PMI) from a user equipment according to a first CSI feedback type,
• wherein the first CSI feedback type is defined when a reporting period of the RI is same as that of the first type PMI, and
• control the receiver to receive a second type PMI with channel quality information (CQI) from the UE according to a second CSI feedback type, the second type PMI being calculated based on a latest RI,
• wherein the RI and the first type PMI are jointly coded, and received through a physical uplink control channel (PUCCH),
• wherein a reporting period of the first CSI feedback type and a reporting period of the second type PMI are defined separately, and
• wherein the reporting period of the first CSI feedback type is equal to or longer than the reporting period of the second type PMI.