Fujitsu Corporation

Junya Morita

Yoshinobu Shizawa

Yousuke Okazaki

Hiroyuki Ogawa

Hiroaki Maeda

Satoshi Matsubara

Yasushi Seino

Tsuneaki Tadano

Hirotoshi Kanno

A first FFT operator converts, with respect to each of analog circuits, a feedback signal x(t) in the time domain that is obtained after a transmission signal d(t) passes through the analog circuit into a feedback signal X(f) in the frequency domain. A second FFT operator converts the transmission signal in the time domain into a transmission signal D(f) in the frequency domain. A phase error calculator calculates, with respect to each of the analog circuits, a phase error C(f) in the frequency domain based on the feedback signal X(f) and the transmission signal D(f). An IFFT operator calculates, with respect to each of the analog circuits, a tap coefficient c(t) of an FIR filter based on the phase error C(f). The FIR filterfilters, with respect to each of the analog circuits, the transmission signal d(t) based on the tap coefficient c(t).

Base station and antenna calibration method

A distortion compensation apparatus including: an amplifier configured to amplify an input signal including a transmission signal and an impulse signal, the transmission signal being converted to a radio frequency signal for transmission, the impulse signal being not converted to a radio signal for transmission, a memory configured to store a plurality of distortion compensation coefficients for compensating distortion to the input signal, each of the plurality of distortion compensation coefficients being associated with an amplitude of the input signal, and a processor configured to select a distortion compensation coefficient from the plurality of distortion compensation coefficients based on an amplitude of the impulse signal included in the input signal, and update the selected distortion compensation coefficient based on the amplified impulse signal include in the amplified input signal.

Distortion compensation apparatus, wireless communication system, and distortion compensation method

A wireless apparatus including: an amplification circuit configured to generate a second signal by amplifying power of a first signal, a calculation circuit configured to calculate a deviation amount of phase deviation of the second signal from the first signal, and a correction circuit configured to correct the phase deviation using a correction method that is selected from a plurality of correction methods based on the deviation amount, the plurality of correction methods among which each power consumption is higher as each correction amount corresponding to each power consumption is greater.

Wireless apparatus

A wireless device includes a digital-to-analog converter that converts a digital transmission signal within a digital signal processing band to an analog transmission signal, a modulator that performs quadrature modulation of an analog transmission signal obtained by the digital-to-analog converter using a first local signal having a first frequency outside a frequency range, the frequency range centered around a center frequency of a transmission signal and having a bandwidth of the digital signal processing band, and outputs a modulated signal, a frequency converter that performs a frequency shift of a modulated signal output from the modulator using a second local signal having a second frequency within the frequency range, and an inhibitor that performs carrier leakage inhibition processing on the digital transmission signal, based on a signal obtained by the frequency converter.

Growing community of inventors

Yokohama, Japan

Junya Morita