1. A base station for a Narrowband Internet of Thing (NB-IoT) system, comprising:a storage, being configured to store scheduling information;
a transceiver; and
a processor electrically connected to the storage and the transceiver, being configured to execute the following steps:
determining that a plurality of user equipments (UEs) are involved in radio resource scheduling and allocation according to the scheduling information;
determining a received signal quality of each of the UEs according to a feedback message received from each of the UEs via the transceiver;
performing a downlink control information (DCI) subframe repetition number evaluation and adjustment procedure according to the received signal quality of each of the UEs to determine whether a DCI subframe repetition number of each of the UEs in a narrowband physical downlink control channel (NPDCCH) needs to be adjusted, and adjusting the DCI subframe repetition number which needs to be adjusted; and
executing the radio resource scheduling and allocation after the DCI subframe repetition number evaluation and adjustment procedure.