Method for transmitting channel information, device thereof, base station, and method for transmitting for base station thereof

A channel information feedback apparatus in a wireless communication system, comprising:

• a channel estimator for estimating a channel receiving by a reference signal;
• a channel information generator for estimating a precoding matrix suitable for the channel estimated by the channel estimator from a Discrete Fourier Transform (DFT) codebook including two or more sets having different similarities of DFT matrixes, configuring a subset by DFT matrixes having a relatively large phase difference from the precoding matrix in a set including the precoding matrix, and generating channel information containing multiple access information on one or more DFT matrixes having a sufficiently low similarity with the precoding matrix within the subset;
• and
• a feedback unit for feeding back the generated channel information.

A base station comprising:

• a layer mapper for mapping a data symbol into a layer;
• a precoder for receiving feedback of channel state information and multiple access information from one or more user equipments and precoding mapped symbols by using each precoding matrix;
• a scheduler for, when the user equipment allows simultaneous accesses of the user equipment and one or more other user equipments, selecting a user equipment to receive data by using the channel state information and the multiple access information and generating precoding matrixes of the precoder;
• and
• an antenna array including two or more antennas for propagating a precoded symbol into an air,
• wherein, when a precoding matrix suitable for a channel estimated by receiving a reference signal by a user equipment is estimated in a Discrete Fourier Transform (DFT) codebook including two or more sets having different similarities of DFT matrixes and a subset is configured by DFT matrixes having a relatively large phase difference from the precoding matrix in a set including the precoding matrix, the multiple access information is information on one or more DFT matrixes having a sufficiently low similarity with the precoding matrix within the subset.

A transmission method of a base station, comprising:

• mapping a data symbol into a layer;
• receiving feedback of channel state information and multiple access information from one or more user equipments and precoding mapped symbols by using each precoding matrix;
• when the user equipment allows simultaneous accesses of the user equipment and one or more other user equipments, selecting a user equipment to receive data by using the channel state information and the multiple access information and generating precoding matrixes of a precoder;
• and
• propagating a precoded symbol into an air through an antenna array including two or more antennas,
• wherein, when a precoding matrix suitable for a channel estimated by receiving a reference signal by a user equipment is estimated in a Discrete Fourier Transform (DFT) codebook including two or more sets having different similarities of DFT matrixes and a subset is configured by DFT matrixes having a relatively large phase difference from the precoding matrix in a set including the precoding matrix, the multiple access information is information on one or more DFT matrixes having a sufficiently low similarity with the precoding matrix within the subset.