ULTRA-WIDEBAND NETWORK SYSTEM AND METHOD CAPABLE OF SWITCHING HIGH RATE MODE OR LOW RATE MODE

An ultra-wideband network system having a high-speed mode and low-speed mode selecting function and a method thereof are provided to enable a high-speed MB-OFDM(Multiband Orthogonal Frequency Division Multiplexing) type and a low-speed DS-CDMA(Direct Sequence Code Division Multiple Access) type to coexist, thereby operating by selecting a high-speed mode or a low-speed mode according to transceived data. An MB-OFDM modem(210) modulates a signal to be transmitted into an MB-OFDM type signal. A DS-CDMA modem(212) modulates the signal to be transmitted into a DS-CDMA type signal. A mode switching unit(220) switches/connects to the MB-OFDM modem(210) or the DS-CDMA modem(212) according to a high-speed mode control signal or a low-speed mode control signal. A PLL(Phase Locked Loop)(290) shifts a frequency phase according to a phase control signal, and fixes the shifted phase as an MB-OFDM or DS-CDMA type frequency phase. A central controller(222) delivers the high-speed control signal or the low-speed control signal to the switching unit(220) according to a user's mode selecting action, and delivers the phase control signal for adjusting a phase of a frequency to be usable in an operational mode to the PLL(290) according to the user's mode selecting action.