User equipment capable of communicating by using N component carriers (CCs) through carrier aggregation, N being greater than or equal to 2, the user equipment comprising: N communication units (101, 102, 10N) configured to execute radio communication with a base station by using each of the N CCs; a controller configured to individually control an operation mode of each of the N communication units; characterized in that it further comprises: a plurality of timers (DIT_A, DIT_M, DIT_N), each configured to report to the controller that a constant time period is elapsed without receiving a further control signal, after receiving, by a communication unit of the N communication units (101, 102, 10N), a control signal from the base station, wherein, when a report from a first timer (DIT A) of the plurality of timers (DIT_A, DIT_M, DIT_N) is received for a first communication unit of the N communication units (101, 102, 10N), the controller is configured to control the operation mode of the first communication unit (101, 102, 10N), so that the operation mode of the first communication unit transitions to a discontinuous reception mode, and wherein a specific plurality of communication units (101, 102, 10N) belonging to the N communication units (101, 102, 10N), the specific plurality of communication units not including the first communication unit, is grouped, so that operation modes of the specific plurality of communication units simultaneously transition to discontinuous reception mode, when a report from a second timer (DIT_M, DIT_N) of the plurality of timers (DIT_A, DIT_M, DIT_N), the second timer being different from the first timer, is received for one of said specific plurality of communication units (101, 102, 10N). N communication units (101, 102, 10N) configured to execute radio communication with a base station by using each of the N CCs; a controller configured to individually control an operation mode of each of the N communication units; characterized in that it further comprises: a plurality of timers (DIT_A, DIT_M, DIT_N), each configured to report to the controller that a constant time period is elapsed without receiving a further control signal, after receiving, by a communication unit of the N communication units (101, 102, 10N), a control signal from the base station, wherein, when a report from a first timer (DIT A) of the plurality of timers (DIT_A, DIT_M, DIT_N) is received for a first communication unit of the N communication units (101, 102, 10N), the controller is configured to control the operation mode of the first communication unit (101, 102, 10N), so that the operation mode of the first communication unit transitions to a discontinuous reception mode, and wherein a specific plurality of communication units (101, 102, 10N) belonging to the N communication units (101, 102, 10N), the specific plurality of communication units not including the first communication unit, is grouped, so that operation modes of the specific plurality of communication units simultaneously transition to discontinuous reception mode, when a report from a second timer (DIT_M, DIT_N) of the plurality of timers (DIT_A, DIT_M, DIT_N), the second timer being different from the first timer, is received for one of said specific plurality of communication units (101, 102, 10N). a plurality of timers (DIT_A, DIT_M, DIT_N), each configured to report to the controller that a constant time period is elapsed without receiving a further control signal, after receiving, by a communication unit of the N communication units (101, 102, 10N), a control signal from the base station, wherein, when a report from a first timer (DIT A) of the plurality of timers (DIT_A, DIT_M, DIT_N) is received for a first communication unit of the N communication units (101, 102, 10N), the controller is configured to control the operation mode of the first communication unit (101, 102, 10N), so that the operation mode of the first communication unit transitions to a discontinuous reception mode, and wherein a specific plurality of communication units (101, 102, 10N) belonging to the N communication units (101, 102, 10N), the specific plurality of communication units not including the first communication unit, is grouped, so that operation modes of the specific plurality of communication units simultaneously transition to discontinuous reception mode, when a report from a second timer (DIT_M, DIT_N) of the plurality of timers (DIT_A, DIT_M, DIT_N), the second timer being different from the first timer, is received for one of said specific plurality of communication units (101, 102, 10N).