RADIO BASE STATION, USER TERMINAL, RADIO COMMUNICATION SYSTEM, AND RADIO COMMUNICATION METHOD

摘要

PROBLEM TO BE SOLVED: To enable prevention of the reduction in utilization efficiency of radio resources even if downlink control information transmitted in a certain sub-frame is small.SOLUTION: A radio base station according to the invention is a radio base station which transmits downlink control information to each user terminal via an enhanced PDCCH frequency multiplexed with a PDSCH. The radio base station comprises: an allocation unit which allocates a plurality of enhanced PDCCH sets each including a plurality of PRB pairs arranged for the enhanced PDCCH to each user terminal such that at least one enhanced PDCCH set overlaps with another user terminal; and a mapping unit which selects an enhanced PDCCH set from the plurality of enhanced PDCCH sets such that in a prescribed sub-frame the number of enhanced PDCCH sets used for transmission of the downlink control information is minimum, and mapping the downlink control information to a PRB pair constituting the selected enhanced PDCCH set.