1. A multimedia mobile communication system station, the multimedia mobile communication system station comprising: a radio frequency unit for converting a radio frequency signal into an analog intermediate frequency (IF) signal; an IF processing unit for converting the analog IF signal into a digital IF signal and for performing functions associated with the multimedia mobile communication station; a baseband processing unit for converting the digital IF signal into a baseband signal and converting the baseband signal into a multimedia signal by decoding the baseband signal; and a control unit for outputting the multimedia signal to a corresponding path, wherein the IF processing unit comprises: a broadcast high-speed converter for converting the analog IF signal into the digital IF signal, and a digital modem unit for performing various functions with respect to the converted digital IF signal and for configuring a reconfigurable digital IF unit according to a software program downloaded via the digital modem unit, wherein the digital modem unit comprises: a Field Programmable Gate Array (FPGA) for adding or upgrading the functions associated with the multimedia mobile communication station according to the downloaded software program, and a Digital Signal Processor (DSP) for processing data at a high bandwidth, wherein the digital modem unit comprises an IF function unit and a modem function unit for optimizing function parts provided with the FPGA and the DSP, and wherein the IF function unit processes the converted digital IF signal and the modem function part programs the FPGA using the downloaded software program according to whether the mobile station is operated by a TSM or the 3GPP TD-SCDMA system.