Method and apparatus for efficient feedback in a wireless communication system supporting multiple antennas

A method for receiving channel status information (CSI) of downlink transmission via uplink in a wireless communication system, the method comprising:

• receiving a joint-coded rank indicator (RI) and a first wideband (WB) precoding matrix indicator (PMI) at a first subframe;
• and
• receiving a wideband channel quality indicator (WB CQI) and a second WB PMI at a second subframe,
• wherein a user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and
• if the RI is Rank-1 or Rank-2, the first PMI indicates one of subsets each having 8 indexes from among 16 indexes of the first PMI of a precoding codebook.

A user equipment (UE) for transmitting channel status information (CSI) of downlink transmission via uplink in a wireless communication system comprising:

• a reception module for receiving a downlink signal from a base station (BS);
• a transmission module for transmitting an uplink signal to the base station (BS);
• and
• a processor for controlling the user equipment (UE) including the reception module and the transmission module,
• wherein the processor, through the transmission module, transmits a joint-coded rank indicator (RI) and a first wideband (WB) precoding matrix indicator (PMI) at a first subframe, and transmits a wideband channel quality indicator (WB CQI) and a second WB PMI at a second subframe,
• a user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and
• if the RI is Rank-1 or Rank-2, the first PMI indicates one of subsets each having 8 indexes from among 16 indexes of the first PMI of a precoding codebook.

A base station (BS) for receiving channel status information (CSI) of downlink transmission via uplink in a wireless communication system comprising:

• a reception module for receiving an uplink signal from a user equipment (UE);
• a transmission module for transmitting a downlink signal to the user equipment (UE);
• and
• a processor for controlling the base station (BS) including the reception module and the transmission module,
• wherein the processor, through the reception module, receives a joint-coded rank indicator (RI) and a first wideband (WB) precoding matrix indicator (PMI) at a first subframe, and receives a wideband channel quality indicator (WB CQI) and a second WB PMI at a second subframe,
• a user equipment (UE) preferred precoding matrix is indicated by a combination of the first PMI and the second PMI, and
• if the RI is Rank-1 or Rank-2, the first PMI indicates one of subsets each having 8 indexes from among 16 indexes of the first PMI of a precoding codebook.