A base station in a spectrum sharing system includes a sensor configured to sense signals over a shared spectrum, a transceiver configured to receive at least one measurement report transmitted from at least one user terminal regarding signals over the shared spectrum sensed by the at least one user terminal and a processor configured to determine whether to utilize the shared spectrum according to the signals over the shared spectrum sensed by the sensor or acquired from the at least one measurement report. A user terminal in a spectrum sharing system includes a sensor configured to sense signals over a shared spectrum, a processor configured to generate a measurement report regarding the signals over the shared spectrum and a transceiver configured to transmit the measurement report to a base station so that the base station determines whether to utilize the shared spectrum according the signals over the shared spectrum.