Abstract:
PURPOSE: A device and a method thereof for giving channel state information (CSI) feedback by using the limited amount of information in a wireless communication system using a massive multiple-input multiple-output (MIMO) operating in a frequency division duplex (FDD) mode are provided for a mobile station to effectively give a base station feedback of the CSI by using the limited amount of feedback information. CONSTITUTION: A control part (620) selects a beam index having a maximum result value by comparing arbitrary function result values having channel coefficients of N as an input. The control part selects a beam index which is above a threshold value which is the constant value of the maximum result value among the function result values. The control part includes the selected beam index in a valid beam index aggregation. The control part estimates channel state information for the valid beam index aggregation. The control part controls a wireless communication part to give a base station feedback of the estimated channel state information and the valid beam index aggregation. [Reference numerals] (610) Wireless communication part; (620) Control part; (623) Channel state estimation part; (625) Valid beam index determination part; (627) Feedback information producing part; (630) Storing part