Fujitsu Corporation

Hiroyoshi Ishikawa

Kazuo Nagatani

Nobukazu Fudaba

Hajime Hamada

Yuichi Utsunomiya

Tokuro Kubo

Yasuyuki Oishi

Toru Maniwa

Takayoshi Ode

Tomoya Ota

Toshio Kawasaki

Alexander Nikolaevich Lozhkin

Hiroyuki Hayashi

Hideharu Shako

Yasuhito Funyu

Satoshi Matsubara

Daisuke Ogawa

Norio Tozawa

Shohei Ishikawa

Hikaru Ishikawa

Takeshi Ohba

Yoji Ohashi

Atsushi Honda

Mitsuharu Hamano

Takenori Ohshima

Shinichiro Kobayashi

Yasuharu Amezawa

Takeshi Sugiyama

Ryo Koizumi

Koichi Hanada

Takuro Nishikawa

Takuro Kubo

Tohru Sasaki

Yuki Kanno

A wireless communication apparatus includes a plurality of antenna elements; a plurality of power amplifiers provided in the plurality of antenna elements; a processor that outputs a transmission signal to the plurality of power amplifiers; and a plurality of feedback paths each of which allows a feedback signal to be fed back from the plurality of power amplifiers to the processor, wherein the processor executes a process for collectively correcting variations in analog characteristics exhibited in the plurality of feedback paths, and a process for updating, by using the transmission signal and the feedback signal that are obtained by being corrected, a distortion compensation coefficient that is used to compensate nonlinear distortion produced in the plurality of power amplifiers.

Wireless communication apparatus and distortion compensation method

A signal processing device includes: a first subarray that includes power amplifiers and phase shifters and that forms a first beam facing in a first direction; a second subarray that includes power amplifiers and phase shifters and that forms a second beam facing in a second direction; a feedback unit that feeds back at least signals that are output from the power amplifiers included in the first subarray; and a processor that is connected to the first subarray and the second subarray. The processor executes a process including: generating, based on a first feedback signal and a transmission signal output to the first subarray, a cancellation signal corresponding to an interference component applied to the second beam by the first beam; and adding the generated cancellation signal to a transmission signal output to the second subarray.

Signal processing device and inter-beam interference suppression method

A wireless communication apparatus includes: a processor that performs distortion compensation on a complex number transmission signal by using a distortion compensation coefficient; a power amplifier that amplifies the transmission signal subjected to distortion compensation by the processor; and a feedback path that feeds back a signal output from the power amplifier to supply a real number feedback signal to the processor. The processor executes a process including: estimating a complex number feedback signal by performing linear computation on the complex number transmission signal and the real number feedback signal; and updating the distortion compensation coefficient by using the estimated complex number feedback signal.

Wireless communication apparatus and coefficient updating method

A peak suppression circuit includes a memory, and a processor coupled to the memory and the processor configured to suppress a first peak of a transmission signal according to a first sampling signal having a predetermined period, delay the transmission signal where the first peak is suppressed by a predetermined time corresponding to a period shorter than the predetermined period, and suppress a second peak of the delayed transmission signal according to a second sampling signal having the predetermined period.

Peak suppression circuit, peak suppression method, and transmitter

A multiantenna communication device forms a directional beam by adding an antenna weight to respective signals of a plurality of antenna elements. The multiantenna communication device includes: a processor that executes performing distortion compensation on a transmission signal by using a distortion compensation coefficient; a plurality of power amplifiers that are provided corresponding to the antenna elements, and that amplify the transmission signal subjected to the distortion compensation by the processor; a multiplexer that multiplexes signals output from the power amplifiers to feed back; and an analog/digital (A/D) converter that A/D converts a multiplex feedback signal that is obtained by the multiplexer, wherein the processor executes updating the distortion compensation coefficient by using the multiplex feedback signal A/D converted by the A/D converter and the transmission signal.

Multiantenna communication device and coefficient update method

A distortion compensating device includes: a filter that receives input of a transmitting signal including a plurality of subcarrier signals assigned to respective frequencies and that superimposes filter coefficients on the respective subcarrier signals; a first signal converting unit that converts the subcarrier signals, on which the respective filter coefficients are superimposed, from a frequency domain into a time domain to obtain an input signal; a distortion compensating unit that superimposes a distortion compensation coefficient on the input signal to obtain an output signal; a power amplifier that amplifies and outputs the output signal; and a control unit that generates the filter coefficients according to an arithmetic equation using the subcarrier signals and a feedback signal from the power amplifier, and outputs the filter coefficients to the filter.

Distortion compensating device and distortion compensation method

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 compensation apparatus including: a memory configured to store a plurality of distortion compensation coefficients for compensating distortion to an input signal amplified by an amplifier, each of the plurality of distortion compensation coefficients being associated with a different combination of two addresses, and a processor configured to receive temperature information associated with a temperature of the amplifier, generate a first address based on the input signal at a first time, generate a second address based on an average of the input signal during a previous period preceding the first time, the average being calculated based on the temperature information, select a distortion compensation coefficient from the plurality of distortion compensation coefficients based on the first address and the second address, and compensate distortion to the input signal based on the selected distortion compensation coefficient.

Distortion compensation apparatus, transmission apparatus, 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.

Growing community of inventors

Kawasaki, Japan

Hiroyoshi Ishikawa