3-D MIMO communication system, radio base station, and user equipment

A user equipment comprising:

• a receiver configured to receive candidates of phase rotation in a horizontal direction and candidates of phase rotation in a vertical direction for precoding;
• and
• a processor configured to report feedback information including a phase rotation in the horizontal direction and a phase rotation in the vertical direction for precoding to a radio base station based upon the candidates of the phase rotation in a horizontal direction and the candidates of phase rotation in a vertical direction for precoding,
• wherein the candidates of phase rotation in the horizontal direction or the candidates of phase rotation in the vertical direction for precoding are a part of predetermined candidates, the part being selected from the predetermined candidates according to a predetermined method, and
• wherein the candidates of phase rotation in the horizontal direction and the candidates of phase rotation in the vertical direction have limited values of phase rotation which set one or more values that correspond to candidates obtained by extracting every nth candidate of phase rotation in the vertical direction at the radio base station.