Mobile communication system for providing carrier aggregation between digital signals and method for processing signal in system thereof

A mobile communication system comprises: a plurality of digital units; a blade server for allocating resources to signals to be processed by the digital units; and a plurality of radio units which are physically separated from the plurality of digital units, convert and amplify a digital signal received from the digital unit so as to transmit the converted and amplified signal to a terminal, and receive a signal transmitted from the terminal so as to transmit the received signal to the digital unit. At this point, the system provides a mobile communication service to the terminal by using carrier aggregation between radio units which are respectively connected to two or more digital units and use different frequencies.