Fujitsu Corporation

Alexander Nikolaevich Lozhkin

Tomoya Ota

Hiroyoshi Ishikawa

Toshio Kawasaki

Yuichi Utsunomiya

Yoshinori Tanaka

Kazuo Nagatani

Toru Maniwa

Yoji Ohashi

Hajime Hamada

Yoichi Kawano

Takeshi Takano

Atsushi Honda

Takenori Ohshima

Masayuki Hosoda

An array antenna system includes DPD that suppresses first IMD in a first band adjacent to a band of a transmission signal, antenna elements that include a first element and a second element, phase shifters that each correspond to each of the elements and form a transmission signal directed to a predetermined direction and second IMD, by applying a weight to the signal and the second IMD in a second band adjacent to the first band, a first amplifier that amplifies the signal directed to the direction and first distortion serving as the second IMD, that are output from a first shifter of the first element, and a second amplifier that amplifies the signal directed to the direction and second distortion a phase of which is opposite to that of the first distortion serving as the second IMD, that are output from a second shifter of the second element.

Array antenna system and nonlinear distortion suppression method

A radio communication device includes: a plurality of antenna elements; a phase shifter that applies weights for each of the antenna elements respectively to first-band data and second-band data of different frequency bands to form beams corresponding to the first-band data and the second-band data; a power amplifier that is arranged for each of the antenna elements; and a processor configured to compensate for non-linear distortion. The processor executes a process including calculating, using a first distortion compensation coefficient, a distortion compensation signal that compensates for in-band non-linear distortion of the first-band data and the second-band data, and calculating, using a second distortion compensation coefficient, an out-of-band compensation signal that compensates for out-of-band non-linear distortion of the first-band data and the second-band data, and the power amplifier amplifies a signal obtained by synthesizing the distortion compensation signal and the out-of-band compensation signal.

Radio communication device and distortion compensation method

A wireless communication device includes: a plurality of power amplifiers provided for a plurality of respective antenna elements, each of the power amplifiers amplifying a signal; a distortion compensation unit that executes distortion compensation of a transmission signal by using an inverse function corresponding to nonlinear distortion generated in the power amplifiers; and a controller that operates by switching a first mode and a second mode, the first mode setting individual inverse functions for the respective power amplifiers in the distortion compensation unit and updating coefficients of the individual inverse functions, the second mode suspending the update of the coefficients of the individual inverse functions and setting, in the distortion compensation unit, an integrated inverse function acquired by performing weighted addition of the individual inverse functions.

Wireless communication device and distortion compensation 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 wireless communication apparatus includes: a plurality of antenna elements; a processor that outputs an in-phase signal and a quadrature signal; a splitter that distributes the in-phase signal and the quadrature signal to the antenna elements; and a plurality of quadrature modulators that generate transmission signals of a radio frequency by performing quadrature modulation on the in-phase signals and the quadrature signals. The processor is configured to execute a process including applying a first frequency shift according to a transmission beam direction to a first oscillation signal that is supplied to the quadrature modulators, digitally modulating transmission data to generate the in-phase signal and the quadrature signal, and performing complex multiplication to the in-phase signal and the quadrature signal with a second oscillation signal to which a second frequency shift opposite from the first frequency shift is applied.

Wireless communication apparatus and wireless communication method

An amplifier circuit includes: a plurality of amplifiers; a plurality of monitor elements provided for each of the plurality of amplifiers and disposed on a same chip with the corresponding amplifier; and a processor configured to: measure characteristics of each of the plurality of monitor elements; reduce a difference in distortion between a plurality of signals output from the plurality of amplifiers based on the measured characteristics; and compensate for the distortion.

Amplifier circuit and antenna device

A wireless communication apparatus includes: a processor that performs distortion compensation on a transmission signal by using a distortion compensation coefficient; an amplifying unit that amplifies the transmission signal; and a feedback path that feeds back a feedback signal to the processor. The processor executes a process including: acquiring, from a transmission signal at a first timing and feedback signals at a second timing that is before the first timing and at a third timing that is after the first timing, instantaneous delay associated with propagation delay of the feedback signals in the feedback path; calculating a mean value of the instantaneous delay acquired in a predetermined time period; adding delay associated with the calculated mean value to the transmission signal; and updating the distortion compensation coefficient by using the transmission signal to which the delay is added and the feedback signal.

Wireless communication apparatus and coefficient update method

A distortion compensation apparatus executes a process including: Performing distortion compensation that compensates in advance for a nonlinear distortion occurring when a transmission signal is amplified by a power amplifier; determining whether power of the transmission signal is smaller than a predetermined threshold; holding a gain relating to the distortion compensation or a result of the distortion compensation when the power of the transmission signal is determined to be smaller than the predetermined threshold; and outputting to the power amplifier, when the power of the transmission signal is determined to be smaller than the predetermined threshold, the result of the distortion compensation, and outputting to the power amplifier, when the power of the transmission signal is determined to be equal to or greater than the predetermined threshold, a result of distortion compensation performed using the held, gain, or the held result of the distortion compensation.

Distortion compensation apparatus and distortion compensation method

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

An optical transmitter includes: an amplitude control circuit, an E/O (Electrical-to-Optical) circuit, a detector and an optical power control circuit. The amplitude control circuit controls an amplitude of an input electric signal to generate a constant amplitude electric signal. The E/O circuit generates a modulated optical signal from the constant amplitude electric signal by a direct modulation. The detector detects an amplitude modulation component of the input electric signal. The optical power control circuit controls a power of the modulated optical signal based on the amplitude modulation component detected by the detector.

Optical transmitter and method for transmitting optical signal

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 transmission device outputs a modulated signal based on amplitude information and phase information respectively indicating an amplitude and a phase of a transmission symbol. The transmission device includes: an oscillation signal generation circuit configured to generate an oscillation signal based on the phase information; a laser light source configured to be driven by the oscillation signal; a bias controller configured to control a bias current of the laser light source based on the amplitude information; a photo detector configured to convert an output light of the laser light source into an electric signal; and a bandpass filter configured to filter an output signal of the photo detector so as to output the modulated signal.

Transmission device with pulse width modulation and transmission system

A communication device includes: a signal generator configured to generate a plurality of intermediate frequency signals; a combiner configured to combine the plurality of intermediate frequency signals to generate a multichannel signal; a reduction unit configured to reduce a peak-to-average power ratio of the multichannel signal; and a converter configured to convert the multichannel signal whose peak-to-average power ratio is reduced by the reduction unit into an optical signal. The reduction unit reduces a power of the multichannel signal using supplemental signals, frequencies of the supplemental signals being different from frequencies of the intermediate frequency signals, when the power of the multichannel signal is higher than a specified threshold level.

Device and method for transmitting optical signal in which a plurality of signals are multiplexed

A communication device includes: a converter circuit configured to convert an optical signal that carries an oscillator signal of a radio frequency and transmission signals generated in a signal processing device into an electric signal; an extractor configured to extract the oscillator signal from the electric signal; a recovery circuit configured to recover the transmission signals from the electric signal; a radio frequency signal generator configured to generate radio frequency signals that respectively carry the transmission signals recovered by the recovery circuit using the oscillator signal; amplifiers respectively configured to amplify the radio frequency signals; antennas respectively configured to output the amplified radio frequency signals; a feedback circuit configured to generate a feedback signal from the amplified radio frequency signals; and a transmitter configured to convert the feedback signal into an optical signal and transmit it to the signal processing device.

Growing community of inventors

Kawasaki, Japan

Alexander Nikolaevich Lozhkin