Precoding apparatus and method in a wireless communication system using multiple input multiple output

An apparatus for transmitting feedback information from a receiver to a transmitter in a Multiple Input Multiple Output (MIMO)-based wireless communication system, the apparatus comprising:

• a channel estimation unit for estimating a state of a channel between the receiver and the transmitter;
• and
• a feedback information transmitter for selecting two precoding matrixes which are most preferred in the estimated channel state and feeding back identification information for identifying the two selected precoding matrixes, to the transmitter,
• wherein the identification information includes one of index information for each of the two selected precoding matrixes, and index information of a precoding matrix corresponding to a combination of the two selected precoding matrixes,
• wherein the two selected precoding matrixes include a first precoding matrix used for intra-group precoding and a second precoding matrix used for inter-group precoding, and
• wherein the intra-group precoding and the inter-group precoding are performed using at least two antenna groups, each of the at least two antenna groups including at least two antennas,
• wherein the intra-group precoding is based on a high spatial correlation to a linear array antenna in a transmit antenna group of the at least two transmit antenna groups and the inter-group precoding is based on a low spatial correlation in between the at least two transmit antenna groups.

A method for transmitting data at a transmitter in a Multiple Input Multiple Output (MIMO)-based wireless communication system, the method comprising:

• receiving identification information for identifying two precoding matrixes, from a receiver;
• and
• transmitting data using the two precoding matrixes selected based on the identification information, wherein the identification information is information for indicating two precoding matrixes, which are most preferred by the receiver based on a channel state estimated between the receiver and the transmitter,
• wherein the identification information includes one of index information for each of the two selected precoding matrixes, and index information of a precoding matrix corresponding to a combination of the two selected precoding matrixes,
• wherein the two selected precoding matrixes include a first precoding matrix used for intra-group precoding and a second precoding matrix used for inter-group precoding, and
• wherein the intra-group precoding and the inter-group precoding are performed using at least two antenna groups, each of the at least two antenna groups including at least two antennas,
• wherein the intra-group precoding is based on a high spatial correlation to a linear array antenna in a transmit antenna group of the at least two transmit antenna groups and the inter-group precoding is based on a low spatial correlation in between the at least two transmit antenna groups.

An apparatus for transmitting data at a transmitter in a Multiple Input Multiple Output (MIMO)-based wireless communication system, the apparatus comprising:

• a receiving unit for receiving identification information for identifying two precoding matrixes, from a receiver;
• and
• a transmission unit for transmitting data using the two precoding matrixes selected based on the identification information,
• wherein the identification information is information for indicating the two precoding matrixes, which are most preferred by the receiver based on a channel state estimated between the receiver and the transmitter,
• wherein the identification information includes one of index information for each of the two selected precoding matrixes, and index information of a precoding matrix corresponding to a combination of the two selected precoding matrixes,
• wherein the two selected precoding matrixes include a first precoding matrix used for intra-group precoding and a second precoding matrix used for inter-group precoding, and
• wherein the intra-group precoding and the inter-group precoding are performed using at least two antenna groups, each of the at least two antenna groups including at least two antennas,
• wherein the intra-group precoding is based on a high spatial correlation to a linear array antenna in a transmit antenna group of the at least two transmit antenna groups and the inter-group precoding is based on a low spatial correlation in between the at least two transmit antenna groups.