Method and device for reporting channel state information in wireless communication system

A method for receiving channel state information (CSI) by a base station (BS) in a wireless communication system, the method comprising:

• transmitting a reference signal to a user equipment (UE);
• and
• receiving the CSI generated using the reference signal by the UE from the UE,
• wherein the CSI is calculated based on tilting in the second domain when the CSI for a 2D antenna structure defined by a first domain and a second domain does not comprise a precoding matrix indicator (PMI) for the 2D antenna structure but comprises a channel quality indicator (CQI) for the 2D antenna structure, and
• wherein the tilting in the second domain is determined based on an assumption that a single antenna transmission and a second domain precoding matrix indicated by a predetermined second domain PMI are applied when the UE performs a fallback operation.

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

• a transmitter;
• a receiver;
• and
• a processor configured to control the transmitter and the receiver,
• wherein the processor further is configured to:
• receive a reference signal from a base station (BS) using the receiver, and
• transmit the CSI generated by the reference signal, to the BS using the transmitter, and
• wherein the CSI is calculated based on tilting in the second domain when the CSI for a 2D antenna structure defined by a first domain and a second domain does not comprise a precoding matrix indicator (PMI) for the 2D antenna structure but comprises a channel quality indicator (CQI) for the 2D antenna structure, and
• wherein the tilting in the second domain is determined based on an assumption that a single antenna transmission and a second domain precoding matrix indicated by a predetermined second domain PMI are applied when the UE performs a fallback operation.

A base station (BS) for receiving channel state information (CSI) in a wireless communication system, the BS comprising:

• a transmitter;
• a receiver;
• and
• a processor using the transmitter,
• wherein the processor is further configured to:
• transmit a reference signal to a user equipment (UE) using the transmitter, and
• receive the CSI generated using the reference signal by the UE, from the UE using the receiver, and
• wherein the CSI is calculated based on tilting in the second domain when the CSI for a 2D antenna structure defined by a first domain and a second domain does not comprise a precoding matrix indicator (PMI) for the 2D antenna structure but comprises a channel quality indicator (CQI) for the 2D antenna structure, and
• wherein the tilting in the second domain is determined based on an assumption that a single antenna transmission and a second domain precoding matrix indicated by a predetermined second domain PMI are applied when the UE performs a fallback operation.