| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a codebook that is expanded by gain information transmittable by the reduced amount of signaling.SOLUTION: One aspect of the invention relates to a user device that includes: a transmitting/receiving unit for communicating a radio signal with a base station by MIMO (Multiple Input Multiple Output) transmission; a codebook storage unit for storing prescribed codebooks that are made up to define each precoding matrix used in the MIMO transmission and express phase information and gain information; a channel measuring unit that measures each channel state on the basis of each reference signal transmitted from a plurality of antennas of the base station; and a codebook selection unit that selects a codebook that should be announced to the base station from the stored codebooks on the basis of the measured channel state, and instructs the transmitting/receiving unit to notify the base station of feedback information including a codebook index identifying the selected codebook.</p> |
