USER TERMINAL, RADIO BASE STATION AND RADIO COMMUNICATION METHOD

摘要

The objective of the present invention is to optimize retransmission control when communicating using a plurality of cells. The configuration is such that: a radio base station (10) transmits transmission data to a user terminal (20); the radio base station transmits, to the user terminal, instruction information for controlling a reception process, to be performed by the user terminal, using a HARQ process; retransmission data from within the transmission data are transmitted using a licensed carrier from among a plurality of cells, said licensed carrier being different from an unlicensed carrier used to transmit the transmission data; and the user terminal receives the retransmission data using the licensed carrier in accordance with the instruction information from the radio base station.