A communication method according to an embodiment comprises: notifying, by a base station, a radio terminal of a discontinuous reception (DRX) cycle; notifying, by a Mobility Management Entity (MME), the radio terminal of an extended DRX cycle longer than the DRX cycle; determining, by the radio terminal, whether or not the base station supports an extend DRX; using, by the radio terminal, the extended DRX cycle to execute an extended DRX operation in an idle mode, in response to determining that the base station supports the extend DRX; and using, by the radio terminal, the DRX cycle to execute a DRX operation without using the extended DRX cycle, in response to determining that the base station does not support the extend DRX.