Present disclosure relates to a base station and a method for operating the same. The base station includes a communicating unit and a processing unit. The communicating unit is wirelessly connected to user equipments in the internet of things. The communicating unit is configured to receive a frequency hopping preamble sequence from a user equipment. The processing unit, electrically coupled to the communicating unit, is configured to obtain frequency hopping energies corresponding to a plurality of symbol groups from the frequency hopping preamble sequence. The processing unit is configured to accumulate the frequency hopping energies and calculate an average energy corresponding to one symbol group according to the accumulated frequency hopping energies. The processing unit is configured to calculate a threshold based on the average energy and a false alarm rate, wherein the threshold is applied to determine whether signals sending from the user equipment are noises.