Fujitsu Corporation

Yasuhito Funyu

Takeshi Ohba

Hideharu Shako

Kazuo Nagatani

Hiroyoshi Ishikawa

Hajime Hamada

Nobukazu Fudaba

Hiroaki Abe

Tokuro Kubo

Tomohiro Nakamura

Norio Tozawa

Yuichi Utsunomiya

Takao Sasaki

Hiromi Miyamoto

Masayuki Watabe

Hisato Kawano

A wireless apparatus includes: an A/D converter which samples an in-phase signal component and a quadrature signal component from a quadrature-modulated signal of analog form alternately; a digital quadrature demodulation unit which applies digital quadrature demodulation to an output signal of the A/D converter and outputs an in-phase signal and a quadrature signal; and an error detection unit which, based on the in-phase and quadrature signals output from the digital quadrature demodulation unit, detects a time difference error between the sample timing of the in-phase signal component and the sample timing of the quadrature signal component.

Wireless apparatus and signal processing method

A bias control signal generation unit detects ON and OFF of a transmission signal input to an amplifier and having a property of a burst according to burst information. The bias control signal generation unit controls a bias voltage to be applied to an amplifier such that an idle current flowing through the amplifier can be flowing in a larger amount in a transmission OFF period, and can return to a normal level in a transmission ON period.

Amplifier control device

A distortion compensating technique applied to a transmitter for transmitting a quadrature modulated signal in a wireless digital communication system is provided. A phase adjustment value is determined for a quadrature demodulated feedback signal based on comparison between the feedback signal and a reference signal to be transmitted from the transmitter. This phase adjustment value is compared with the previous phase adjustment value. If the comparison result between the current and previous phase adjustment values satisfies a prescribed condition, correction for quadrature modulation, such as DC offset correction, orthogonality correction, or IQ amplitude correction, is performed.

Distortion compensation in wireless digital communication

The apparatus includes: distortion amount detector which detects the amount of distortion of an output signal of an amplifier; parameter holder which holds a parameter having been set therein, the parameter holder being capable of varying the difference according to the parameter set therein; parameter corrector which corrects the parameter held in the parameter holder in such a manner that the distortion amount detected by the distortion amount detector is improved; noise component detector which detects a noise component that can be caused in the output signal resulting from a quadrature modulation; and noise component remover which performs processing for removing the noise component detected by the noise component detector. This arrangement makes it possible to suppress image frequency component generation in an output signal of the amplifier accompanying quadrature modulation and to optimize parameters in distortion compensation.

Distortion compensating apparatus and method

A reference signal and a feedback signal are written to memory and the state of a power value of a reference signal is used for judging whether the current signal is in a normal state, burst state, non-modulation state or no-wave transmission state. If the state is judged to be the burst state or no-wave transmission state, a DC offset correction is performed by selecting a feedback signal type DC offset correction method in which a DC offset is corrected by using only a feedback signal. If the state is judged to be the normal state or non-modulation state, a DC offset correction is performed by selecting a reference signal type DC offset correction method in which a DC offset is corrected by using a differential signal between the reference signal and feedback signal.

DC offset correction apparatus and method

In a network employing code division multiplex access, a distortion compensation amplifying apparatus is provided which is capable of making quick response to carry out the distortion compensation with high accuracy even if the signal power to be inputted thereto varies rapidly. In this distortion compensation amplifying apparatus, the renewal of a distortion compensation coefficient in a renewing unit is complemented on the basis of a result of amplification in an amplifier with respect to a signal code-division-multiplexed in a pseudo-signal multiplexing unit.

Distortion compensation amplifying apparatus and base station

A step size parameter &#x3bc; is adaptively varied when a distortion compensation coefficient is calculated in a distortion compensation apparatus, relation between transmission signal level and step size parameter &#x3bc; is considered. The distortion compensation apparatus includes a memory storing distortion compensation coefficient in a designated write address, and outputting distortion compensation coefficient being stored in a designated readout address; a predistortion section performing distortion compensation processing onto a transmission signal, using the distortion compensation coefficient being output from memory; and a distortion compensation section calculating an update value of distortion compensation coefficient, based on error component existent between transmission signal before distortion compensation processing and transmission signal after being amplified by an amplifier. Further, the distortion compensation section modifies magnitude of step size parameter determining degree of effect of error component produced on the update value, when calculating the update value of the distortion compensation coefficient.

Distortion compensation apparatus

An address frequency operation unit counts frequencies of occurrences of addresses output by an address conversion unit, and a CPUrewrites an address conversion table in the address conversion unitbased on a comparison between the counted result and a threshold value. When the frequency of the address is lower than the threshold value, the frequency of occurrence of an output address is increased by increasing the number of input addresses corresponding to one output address. Also, distortion in an output signal which is fed back is detected and the address conversion table is rewritten so that the distortion is decreased.

Address generating device and method of generating address

In a delay regulating device, delay regulation is performed using a delay circuit performing delay regulation in a clock unit and a delay filter performing delay regulation in a tap unit smaller than the clock unit. The delay regulation is performed so as to obtain the maximum value of the correlation value and the minimum value of the error signal. First the delay circuit based on the clock unit is used to control the delay amount of the reference signal so as to obtain the maximum value of the correlation value. The delay filter is used to control the delay amount of the feedback signal so as to obtain the maximum value of the correlation value. Phase adjustment of the reference signal and the feedback signal is performed. The delay amount of the feedback signal is regulated so as to minimize the error signal unit using the delay filter.

Delay regulating device

A distortion compensation apparatus shortens the time until start of the transmission. The distortion compensating apparatus for amplifying the transmitted signal after implementation of the distortion compensation process thereto comprises a coefficient memory operable to store coefficients used for the distortion compensation process, an initial value memory operable to store the initial values of the coefficients, and a controller which controls the coefficient memory to store, with limitation, only the coefficients corresponding to the first portion among those stored in the initial value memory for the initial write to the coefficient memory and to store thereafter the coefficients corresponding to the second portion.

Distortion compensating apparatus

Provided is a distortion compensation apparatus to prevent divergence of distortion compensation coefficients caused by an abnormal distortion compensation coefficient value. The distortion compensation apparatus includes a storage for storing a distortion compensation coefficient in a specified write address, and outputting a distortion compensation coefficient stored in a specified readout address; a predistortion portion for performing distortion compensation processing onto a transmission signal, using the distortion compensation coefficient being output from the storage; and a distortion compensator for calculating a distortion compensation coefficient based on the transmission signal before the distortion compensation processing and the transmission signal after being amplified by an amplifier. The distortion compensator further reads out the distortion compensation coefficients stored in the storage, extracts a distortion compensation coefficient satisfying a predetermined condition, and performs correction processing to reduce the amplitude of the extracted distortion compensation coefficient.

The distortion compensating apparatus which adaptively updates a distortion compensation coefficient for an amplifier based on a difference between input and output signals of the amplifier, comprises: a distortion amount detector which detects the amount of distort of an output signal of the amplifier; a parameter holder which holds a parameter having been set therein; a parameter corrector which corrects the parameter in such a manner that the distortion amount detected by the detector is improved; and a distortion amount corrector which corrects the distortion amount detected by the detector in such a manner that the distortion amount is reduced by an offset amount according to a detection error. This arrangement makes it possible to accurately set the parameter relating to difference detection which is a factor of updating of distortion compensation coefficients of the distortion compensating apparatus.

A distortion compensation apparatus is provided to restrain an increased calculation time caused by a large amount of calculation required for obtaining a phase variation amount for compensation from the correlation. The distortion compensation apparatus includes an update calculation section calculating a distortion compensation coefficient by use of an adaptive algorithm; a distortion compensation section performing distortion compensation to the transmission signal, based on the distortion compensation coefficient being read out from the distortion compensation coefficient storage; a correlation calculation section calculating a real part of correlation and an imaginary part of correlation of each the reference signal and the feedback signal; and a phase rotation section compensating a relative phase deviation between the reference signal and the feedback signal, based on the real part of correlation and the imaginary part of correlation calculated by the correlation calculation section, wherein the update calculation section calculates a distortion compensation coefficient using the post-compensation signal.

The present invention is a carrier state judging device having a multiplexing unit multiplexing carrier signals to be inputted in parallel, output control units inputted to the multiplexing unit and performing ON/OFF control of outputs of the carrier signals inputted to the output control units themselves according to predetermined ON/OFF setting values, frequency shift units and giving predetermined frequency shift quantities to the carrier signals inputted to the frequency shift units themselves, a detection unit detecting as to whether or not there is the carrier signal flowing through on each carrier signal transmission path, and a determining unit determining a state of the carrier signals multiplexed by the multiplexing unit on the basis of the ON/OFF setting value with respect to each of the output control units, the frequency shift quantity with respect to each of the frequency shift units and a result of the detection by the detection unit.

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Kawasaki, Japan

Yasuhito Funyu