Base station, system, and method and program for forming a null of antenna directivity

A method for forming a null of an antenna directivity in a base station that is provided with a multi-element antenna for performing beamforming control using a codebook consisting of a set of plural precoding weight matrices corresponding to plural candidates of beams used for performing a radio communication with a terminal in a cell, and fixedly installed on land or at sea, the method comprising:

• determining plural sets of codebook subsets that are grouped by each of sets of plural precoding weight matrices corresponding to plural beams orthogonal to each other, based on the codebook;
• selecting, from the plural sets of codebook subsets, a codebook subset consisting of a set of plural precoding weight matrices corresponding to plural beams orthogonal to each other, the plural beams including an interference beam that has a maximum gain in a direction of an interference-receiving object, as the codebook subset to be used for the beamforming control;
• and
• stopping a use of plural beams corresponding to unselected codebook subsets other than the selected codebook subset, and stopping a use of the interference beam among the plural beams corresponding to the selected codebook subset, in the beamforming control.

A non-transitory computer readable storage medium containing software that is executed in a computer or processor provided in a base station that is provided with a multi-element antenna for performing a beamforming control using a codebook consisting of a set of plural precoding weight matrices corresponding to plural candidates of beams used for performing a radio communication with a terminal in a cell, and fixedly installed on land or at sea, the software comprising:

• executable code that determines plural sets of codebook subsets that are grouped by each of sets of plural precoding weight matrices corresponding to plural beams orthogonal to each other, based on the codebook;
• executable code that selects, from the plural sets of codebook subsets, a codebook subset consisting of a set of plural precoding weight matrices corresponding to plural beams orthogonal to each other, the plural beams including an interference beam that has a maximum gain in a direction of an interference-receiving object, as the codebook subset to be used for the beamforming control;
• and
• executable code that stops a use of plural beams corresponding to unselected codebook subsets other than the selected codebook subset, and stops a use of the interference beam among the plural beams corresponding to the selected codebook subset, in the beamforming control.