Patent ID: 8903328

Claim:
A method for transmitting channel status information (CSI) of downlink transmission via a physical uplink control channel (PUCCH) in a wireless communication system, the method comprising: transmitting, by a user equipment (UE) to a base station (BS), a rank indicator (RI) and a precoder type indicator (PTI) at a first subframe; determining, by the UE, if the PTI has a first value or a second value different from the first value; when the PTI has the first value, transmitting, by the UE to the BS: a first precoding matrix indicator (PMI) for a wideband (WB) at a second subframe, a second PMI for the WB and a channel quality indicator (CQI) for the WB at a third subframe; and when the PTI has the second value, transmitting, by the UE to the BS: the second PMI for the WB and the CQI for the WB at the second subframe, and the second PMI for a subband (SB) and the CQI for the SB at the third subframe, wherein the RI, the first PMI, the second PMI, and the CQI are contained in channel status information (C SI) of downlink 8 transmission (Tx) antennas, wherein a user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and wherein the second PMI is defined as 2-bit information only for each of Rank- 2 , Rank- 3 and Rank- 4 , when codebook subsampling for a PUCCH report mode is applied.