Method for applying amplitude use to digital amplyfier with variable bit resolution or clock frequency and apparatus for excuting the method

A method for applying amplitude use to a digital amplifier with variable bit resolution or clock frequency and an apparatus for executing the method are provided to change bit resolution, a clock frequency, and a modulation scheme according to the state of a wireless transmission channel, thereby ensuring effective utilization of resources of a system and a maximum transmission rate without data error in a given channel state. A transmitter(110) includes a modulator(111), a D/A(Digital/ Analog) converter(112), and an RF(Radio Frequency) processor(113), and a receiver(120) includes an RF processor(121), an A/D converter(122), a demodulator(123), and SNR(Signal to Noise Ratio) calculator(124), and a modulation controller(125). Upon receiving digital data to be transmitted from an upper layer, a modulator modulates the digital data using a predetermined digital modulation scheme or a modulation scheme feedbacked from the receiver, and provide the modulated signal to the D/A converter. The D/A converter converts the modulated signal into an analog signal through a digital filtering using bit resolution feedbacked from the receiver or predetermined bit resolution, and provides the converted signal to the RF processor. Also, the D/A converter converts the modulated signal into the analog signal using a clock frequency instead of using the bit resolution. The D/A converter 112 performs oversampling the digital signal with a corresponding clock frequency using a clock frequency feedbacked from the receiver or a predetermined clock frequency, converts the signal into the analog signal through a digital filtering, and provides the converted signal to the RF processor. The RF processor includes a filter and front end unit, and the like. Also, the RF processor receives a signal of a high frequency band, which passes through a wireless channel, to convert into a baseband signal, and outputs the converted signal. The A/D converter converts the analog baseband signal of the RF processor into a digital signal using bit resolution set by the modulation controller or clock frequency and outputs the converted signal. The modulator receives the digital signal converted through the A/D converter, demodulates the signal using a digital modulation scheme used when the transmitter transmits a signal, and transmits the demodulated signal to the upper layer. The SNR calculator calculates an SNR of an analog signal received through the RF processor and provide the calculated value to the modulation controller. The modulation controller searches a setting table predetermined by an experiment for a modulation scheme and bit resolution corresponding to the SNR using the SNR provided from the SNR calculator.