Fujitsu Corporation

The University of Electro-Communications

Fujitsu Limied

Kazuo Nagatani

Hiroyoshi Ishikawa

Hajime Hamada

Nobukazu Fudaba

Yasuyuki Oishi

Yuichi Utsunomiya

Tokuro Kubo

Yoshihiko Asano

Hidenobu Fukumasa

Takayoshi Ode

Toru Maniwa

Toshio Kawasaki

Hiroyuki Hayashi

Hideharu Shako

Michiharu Nakamura

Tomoya Ota

Hideto Furukawa

Yasuhito Funyu

Takeshi Takano

Yoshiharu Tajima

Alexander Nikolaevich Lozhkin

Satoshi Matsubara

Daisuke Ogawa

Mitsuharu Hamano

Eisuke Fukuda

Norio Tozawa

Shohei Ishikawa

Hikaru Ishikawa

Yoshinori Tanaka

Hiroyuki Seki

Dai Kimura

Takeshi Ohba

Koji Matsuyama

Morihiko Minowa

Kaoru Yokoo

Satoshi Nakamura

Kensuke Sawada

Noriyuki Kawaguchi

Yasuharu Amezawa

Ryo Koizumi

Takeshi Sugiyama

Yasushi Yamao

Takuro Nishikawa

Tohru Sasaki

Yuki Kanno

Koichi Hanada

Takuro Kubo

A distortion compensation apparatus includes a retention unit that retains a coefficient for distortion compensation for each of a plurality of time segments of a burst signal that keeps a constant power level, and a distortion compensation unit that, by using a coefficient for a time segment that corresponds to elapsed time from a head of the burst signal among the coefficients retained by the retention unit, executes distortion compensation for the time segment.

Distortion compensation apparatus and distortion compensation method

A distortion compensation device includes: a storage configured to store a distortion compensation coefficient for compensating a distortion of a transmission signal to be amplified and transmitted, by corresponding to a combination of a plurality of addresses; a first generator configured to generate a first address according to a power or an amplitude of an input signal; a second generator configured to generate a second address according to a first vector to interconnect sample points on an IQ plane where the sample points of the input signal are drawn in time series; and a distortion compensation unit configured to acquire the distortion compensation coefficient corresponding to a combination of the first address and the second address from the storage, and to perform a predistortion processing on the input signal, by using the acquired distortion compensation coefficient, so as to generate the transmission signal.

Distortion compensation device and distortion compensation method

A radio communication device includes: an instantaneous coefficient acquisition unit that acquires an instantaneous coefficient that corrects an instantaneous change contained in a burst distortion corresponding to an elapsed time from a top of a burst signal in which a constant power level continues and instantaneously changes the power level of the burst signal; an average coefficient acquisition unit that acquires an average coefficient that corrects an average change contained in the burst distortion and gradually changes the power level of the burst signal from the top to an end of the burst signal; a synthesizer that synthesizes the instantaneous coefficient acquired by the instantaneous coefficient acquisition unit with the average coefficient acquired by the average coefficient acquisition unit; and a corrector that uses a correction coefficient obtained from the synthesizing by the synthesizer to correct the burst distortion occurring in the burst signal.

Radio communication device and burst distortion correcting method

A peak suppression device includes an acquiring unit that acquires multiple envelopes of carrier signals that are included in a multicarrier signal, an adding unit that adds the envelopes to generate a combined envelope, a detecting unit that detects a peak value and a peak timing of the multicarrier signal by using the combined envelope, and a suppressing unit that suppresses a peak of the multicarrier signal in accordance with the peak value and the peak timing.

Peak suppression device

A distortion compensation device includes a multiplier, a subtracter, an LUT, and a distortion compensation unit. The multiplier calculates the product of amplitudes or the product of power of transmission signals at two different times or calculates the ratio of amplitudes or the ratio of power of transmission signals at two different times. The subtracter calculates the phase difference between the transmission signals at two different times. The LUT specifies a distortion compensation coefficient by using both the product or the ratio calculated by the multiplier and the phase difference calculated by the subtracter. The distortion compensation unit performs, by using the distortion compensation coefficient specified by the LUT, a predistortion process on the transmission signal that is input to the amplifier.

A peak suppression device includes a suppression-signal generating unit and a band pass filter (BPF). The suppression-signal generating unit generates a suppression signal that is obtained by adding, to a transmission signal, a frequency component in which components of frequencies from a boundary of a band of the transmission signal to a frequency that is away therefrom toward an out-band of the transmission signal by predetermined frequencies are attenuated, out of frequency components of a signal to suppress a peak of the transmission signal. The BPF attenuates, after the suppression signal is amplified by the amplifier, a frequency component outside the band of the transmission signal in the amplified suppression signal.

Peak suppression device and peak suppression method

A distortion compensator that compensates for nonlinear distortion of an amplifier that amplifies power of a multicarrier signal includes a first compensation unit that performs first distortion compensation to collectively compensate for first nonlinear distortion that occurs in contact with a carrier frequency of the multicarrier signal, and second nonlinear distortion that occurs at a frequency at a predetermined distance from the carrier frequency, and a second compensation unit that performs second distortion compensation to compensate for only the first nonlinear distortion, of the first nonlinear distortion and the second nonlinear distortion.

Distortion compensator and distortion compensation method

A peak suppression apparatus includes an acquiring unit that acquires a first signal represented by an amplitude waveform of a multicarrier signal, a generator that generates a second signal represented by a waveform sequentially connecting a plurality of peak points adjacent to one another in the first signal as a peak detection signal for the multicarrier signal, a detector that detects a peak value and a peak timing of the multicarrier signal by using the peak detection signal, and a suppressing unit that suppresses a peak of the multicarrier signal based on the peak value and the peak timing.

Peak suppression apparatus

A power amplifier apparatus includes an amplifier configured to amplify an input signal converted into an analog signal, a distortion compensator circuitry configured to perform a pre-distortion process to an input signal at a second sampling rate higher than a first sampling rate at which the input signal is converted into an analog signal, a remover configured to remove a frequency component exceeding a frequency band corresponding to the first sampling rate from the input signal subjected to the pre-distortion process, a first rate converter configured to convert a sampling rate of the input signal from which the frequency component is removed from the second sampling rate to the first sampling rate, and a first signal converter configured to convert the input signal the sampling rate of which is converted into an analog signal at the first sampling rate to supply the input signal converted into the analog signal to the amplifier.

Power amplifier apparatus, transmitter apparatus, and method of controlling the power amplifier apparatus

A wireless transmission apparatus includes an amplifier that amplifies power of a multicarrier signal, a first frequency shift unit that performs a first frequency shift on a first signal fed back from the amplifier on the basis of carrier frequencies of the multicarrier signal to output a second signal after the first frequency shift, a band limiting unit that performs frequency band limitation on the second signal to output a third signal after the frequency band limitation, and a distortion compensation device that compensates nonlinear distortion of the amplifier on the basis of the third signal.

Wireless transmission apparatus and distortion compensation method

A distortion compensation apparatus that compensates nonlinear distortion of an amplifier that amplifies power of a multi-carrier signal includes a band limiting unit that places a first frequency band limitation on a first signal fed back from the amplifier to output a second signal after the first frequency band limitation, a decision unit that decides a first cutoff frequency of the first frequency band limitation based on a carrier interval of the multi-carrier signal, and an updating unit that updates a distortion compensation coefficient to be used for compensation of the nonlinear distortion, based on an error between the second signal and the multi-carrier signal.

Distortion compensation apparatus, wireless transmission apparatus, and distortion compensation method

An amplifying device including: a first amplifier configured to generate a first output signal by amplifying an input signal, a second amplifier configured to generate a second output signal by amplifying the first output signal, and a processor configured to perform a first compensation by compensating a distortion for the second amplifier in accordance with the first output signal and the second output signal.

Amplifying device, distortion compensating device, and amplifying method

A distortion compensation device which compensates for a distortion of an amplifier includes an FIR filter, a calculation unit that calculates an error between a reference signal and a feedback signal from the amplifier, an update unit that updates a coefficient set to the FIR filter on the basis of the error, and a delay unit that, on the basis of a magnitude of the coefficient, delays the feedback signal while controlling a delay of the feedback signal with respect to the reference signal.

A distortion compensation apparatus including: a processor configured to generate a pre-distortion signal by compensating an input signal for a distortion based on a distortion compensation coefficient and a plurality of delayed signals obtained by delaying the input signal by a plurality of amounts of delay, and an amplifier configured to generate an amplified signal by amplifying the pre-distortion signal, wherein the processor calculates the distortion compensation coefficient based on the input signal, the pre-distortion signal, and the amplified signal, and calculates the plurality of amounts of delay based on the amplified signal.

A delay quantity estimation apparatus comprises a first correlation value arithmetic unit to calculate a first correlation value as a correlation value between a first input signal and a feedback signal delayed with a first delay value; a second correlation value arithmetic unit to calculate a second correlation value as a correlation value between the first input signal and a feedback signal delayed with a second delay value; and a delay quantity estimation unit to estimate a delay quantity of the feedback signal with respect to the input signal on the basis of the first difference value as a difference between the first correlation value and the second correlation value, wherein the second delay value is a value given by adding a certain value to the first delay value.

Delay quantity estimation apparatus and delay quantity estimation method

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Kawasaki, Japan

Kazuo Nagatani