Abstract: A wireless communication system includes a baseband processing device configured to transmit a data signal via an optical transmission line, and a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, wherein the wireless device is configured to amplify the data signal to generate the output signal, generate a feedback signal according to the output signal, and transmit the feedback signal to the baseband processing device via the optical transmission line, and wherein the baseband processing device is configured to acquire the feedback signal from the wireless device, and execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.

Abstract: An arithmetic method calculates a first correction coefficient for correction distortion due to a power amplifier based on a first feedback signal that has been fed back from an output of the power amplifier and an input signal before being input to the power amplifier. The arithmetic method also calculates a second correction coefficient for correcting the phase and amplitude of a signal to be output from a filter disposed behind the power amplifier, based on a second feedback signal that has been fed back from an output of the filter and the input signal.

Abstract: A wireless communication system includes a baseband processing device configured to transmit a data signal via an optical transmission line, and a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, wherein the wireless device is configured to amplify the data signal to generate the output signal, generate a feedback signal according to the output signal, and transmit the feedback signal to the baseband processing device via the optical transmission line, and wherein the baseband processing device is configured to acquire the feedback signal from the wireless device, and execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.

Abstract: A wireless communication system includes a baseband processing device configured to transmit a data signal via an optical transmission line, and a wireless device configured to receive the data signal via the optical transmission line and carry out wireless transmission of an output signal obtained by amplifying the data signal, wherein the wireless device is configured to amplify the data signal to generate the output signal, generate a feedback signal according to the output signal, and transmit the feedback signal to the baseband processing device via the optical transmission line, and wherein the baseband processing device is configured to acquire the feedback signal from the wireless device, and execute first processing of multiplying the data signal by a distortion compensation coefficient corresponding to an inverse characteristic of distortion in the radio frequency circuit based on the feedback signal.

Abstract: An transmission apparatus includes a pseudo data addition section configured to add pseudo data into transmission data for a free subcarrier of a radio frequency, an OFDM modulator subjecting the transmission data added with the pseudo data to OFDM modulation, a power amplifier amplifying power of a transmission signal of the radio frequency, the transmission signal based on an OFDM signal subjected to the OFDM modulation, an antenna radiating the amplified transmission signal by using the radio frequency; and a distortion compensation circuit compensating for a distortion characteristic of the power amplifier by correcting the OFDM signal with a distortion compensation coefficient accumulated corresponding to the power value of the OFDM signal, outputting the corrected signal for the power amplifier, and monitoring the output of the power amplifier to update the distortion compensation coefficient.

Abstract: A transmission apparatus performs distortion compensation on a power amplifier using a distortion compensator that includes an adaptive equalizer. The transmission apparatus includes a filter coefficient storage unit that stores filter coefficients that are each set in a digital filter of the adaptive equalizer; a filter coefficient setting unit that selects a filter coefficient from the filter coefficient storage unit according to a feedback signal from the power amplifier; an adjustment value storage unit that stores adjustment values in association with transmission frequencies, the adjustment values each being used by the filter coefficient setting unit to select the filter coefficient; and an initial value setting unit that reads an adjustment value corresponding to a transmission frequency, which is set in the transmission apparatus, from the adjustment value storage unit and sets the read adjustment value as an initial value of the adjustment value used for selecting the filter coefficient.

Abstract: An transmission apparatus includes a pseudo data addition section configured to add pseudo data into transmission data for a free subcarrier of a radio frequency, an OFDM modulator subjecting the transmission data added with the pseudo data to OFDM modulation, a power amplifier amplifying power of a transmission signal of the radio frequency, the transmission signal based on an OFDM signal subjected to the OFDM modulation, an antenna radiating the amplified transmission signal by using the radio frequency; and a distortion compensation circuit compensating for a distortion characteristic of the power amplifier by correcting the OFDM signal with a distortion compensation coefficient accumulated corresponding to the power value of the OFDM signal, outputting the corrected signal for the power amplifier, and monitoring the output of the power amplifier to update the distortion compensation coefficient.

Abstract: A radio transmission apparatus does not update the distortion compensation coefficient for a certain period, which is shorter than the transmission period, after the transmission period start timing. Instead, update operation of the distortion compensation coefficient is carried out after the lapse of a certain period from the start timing. Further, in order to shorten the convergence time of the distortion compensation coefficient, the radio transmission apparatus performs interpolation processing of the distortion compensation coefficient. The distortion compensation coefficient is given to a two-dimensional coordinate (address): one is the power level of an input transmission signal and the other is the difference of power between the input transmission signal and a feedback signal.