The Frequency Shift Repeater is designed to solve problems of weak mobile signal, which can expand more coverage than RF repeater and reduce investment for the areas where fiber optic or dedicated cable is not allowed. The system consists of two parts: Donor unit and Remote unit. The Donor unit receives the BS signal via open air RF transmission or direct coupler closed to BS, then coverts it from the working channel to transmission channel that is out of working frequency band, and transmits the amplified signal to the Remote unit that will reconvert the signal to the working channel and provide signal to the areas where network coverage is inadequate.