USER EQUIPMENT AND BASE STATION

摘要

User equipment which performs communication using cell groups under different base stations comprises: a reception unit which receives, from the base station of a maser cell group, a parameter for a security key for communicating with a secondary cell group; a security key setting unit which sets the security key for communicating with the secondary cell group; a security key setting completion notification unit which notifies the base station of the secondary cell group of the completion of setting of the security key by a random access procedure; and a transmission/reception start determination unit which starts the transmission of uplink data and reception of downlink data using the set security key when the random access procedure is completed.