Fujitsu Corporation

The University of Electro-communications

Eisuke Fukuda

Hiroshi Nakamura

Yasuyuki Oishi

Susumu Sasaki

Kazuo Nagatani

Takeshi Takano

Yukio Takeda

Yoshimasa Daido

Kazuhisa Obuchi

Kazuo Kawabata

Jianming Wu

Hideto Furukawa

Tomohiko Taniguchi

Kazuo Asakawa

Takashi Kimoto

Mitsuhiro Azuma

Sadao Takenaka

Yasushi Yamao

In order to properly expel one or more mobile terminals from a cell that a wireless base station is accommodating, the management station includes at least one processor configured to obtain, for each of the plurality of mobile terminals, speed data indicating a moving speed of the mobile terminal; select one or more mobile terminals each having a moving speed, indicated by the speed data, satisfying a first criterion among the plurality of mobile terminals; and control the wireless base station such that the selected mobile terminals are out of communication with the cell.

Wireless communication system, management station, and method for managing

An amplifier module is expressed by a model having a first filter that is a linear time-invariant filter for limiting the bandwidth of an input signal, an amplifier unit that amplifies a signal output from the first filter, and a second filter that is a linear time-invariant filter for limiting the bandwidth of a signal output from the amplifier unit. A memoryless amplifier unit calculates an output from the amplifier module when being memoryless, using AM-to-AM distortion and AM-to-PM distortion of the amplifier unit. A cross-correlation calculating unit calculates a correlation between the signal output from the amplifier module and the output calculated by the memoryless amplifier unit and calculates an estimate of a transfer function of the first filter and the second filter. A distortion compensating unit compensates the input signal based on the estimate of the transfer function and outputs the signal to the amplifier module.

Distortion compensating apparatus, transmitter, distortion compensating method, and transfer function calculating method

A transmission circuit comprises a &#x3a3;&#x2212;&#x394; modulator to perform &#x3a3;&#x2212;&#x394; modulation of an amplitude modulation component of a modulation signal and to output a pulse width modulation signal, an angle modulator to generate an angle modulation component signal of a signal obtained by multiplying the modulation signal by a transmission output control coefficient corresponding to a transmission output in a power amplifier, and a multiplier to multiply the pulse width modulation signal by the angle modulation component signal and to output a result of the multiplication as an output signal to the power amplifier.

Transmission circuit

Node-B transmits a power profile of each frequency of transmission data as a step function to a UE. Each UE measures the amount of interference of a received signal, evaluates SINR over the entire frequency band with the power of the received signal, and transmits the evaluation result to Node-B. Node-B evaluates the interference profile in Node-B from the information about the SINR transmitted from the UE and the power of the transmission signal, and determines the frequency profile of the power of the signal transmitted to the UE.

Communication apparatus

A amplifier having distortion compensation is employed as a power amplifier for amplifying a linear modulated signal or a low noise amplifier for amplifying a linear modulated signal. The amplifier having distortion compenssation includes an amplifier circuit for amplifying an input signal; an error detecting circuit for obtaining an error signal between the input signal to and an output signal from the amplifier circuit; a coefficient generating circuit for generating compensation coefficients to compensate distortion components of characteristics of the amplifier circuit, based on the error signal according to an adaptive type algorithm; a first outputting circuit for outputting a generated compensation coefficient corresponding to the input signal; and a multiplying circuit for multiplying the generated compensation coefficient to the input signal and inputting a multiplied coefficient to the amplifier circuit.

Amplifier having distortion compensation and base station for radio

A waveform equalizer for equalizing a distorted signal, contains a sampling unit, a time series generating unit, and an equalization neural network unit. The sampling unit samples the level of a distorted signal at a predetermined rate. The time series generating unit serially receives the sampled level and outputs in parallel a predetermined number of the levels which have been last received. The equalization neural network unit receives the outputs of the time series generating unit, and generates an equalized signal of the distorted signal based on the outputs of the time series generating unit using a set of equalization network weights which are preset therein. The waveform equalizer may further contain a distortion characteristic detecting unit, an equalization network weight holding unit, and a selector unit. The distortion characteristic detecting unit detects a distortion characteristic of the distorted signal. The equalization network weight holding unit holds a plurality of sets of equalization network weights each for being set in the equalization neural network unit. The selector unit selects one of the plurality of sets of equalization network weights according to the distortion characteristic which is detected in the distortion characteristic detecting unit, and supplies the selected set in the equalization neural network unit to set the selected set therein.

Waveform equalizer using a neural network

A radio communication system using a QAM system. In the transmission system, the data of each channel to be transmitted is divided into data groups having frame slots. When the polarity of the mean value of a data summed in a present data group is the same as the polarity of the mean value of the deviation of all data group coming before, all data in the present data group is inverted, a direct current component and a lower frequency component near the direct current component are suppressed, and carrier waves are injected after encoding. In the receiving system, a decoder decodes a received signal to obtain the original data before the encoding by the transmission system.

Radio communication system

A receiver unit in a radio communication system in which a transmitter unit outputs transmission data, modulated in accordance with a multilevel QAM method and containing a leakage carrier by addition of a DC offset signal to either one of the quadrature components forming the transmission data, to the receiver unit through a transmission line, including: means for receiving the transmission data; means for branching a signal received at the transmission data receiving means into first and second signal components forming the multilevel QAM data, each including the leakage carrier having a phase difference of .pi./2 radian; first channel means for demodulating the first branched signal component and including a first synchronous detection circuit and a first discriminator; second channel means for demodulating the second branched signal component and including a second synchronous detection circuit and a second discriminator; and means for recovering the carrier including a control circuit, for cancelling a noise component contained in the output signal from either one of the first and second synchronous detection circuits and for providing only a DC component representing a phase difference between a leakage carrier and a reference carrier, and a phase-locked loop (PLL) circuit, for controlling the phase difference to zero and for providing phase-locked leakage carriers to the reference carriers, having a phase difference of .pi./2 radian, to the first and second synchronous detection circuits.

Receiver unit in radio communication system

A radio communication system includes a transmitter unit, a transmission line, and a receiver unit. The transmitter unit modulates an in-phase-channel (I-ch) data signal and quadrature-channel (Q-ch) data signal with two carriers having a .pi./2 phase difference with each other. A DC offset is added to either one of the I-ch and Q-ch data signals before they are modulated. In the receiver unit, a demodulation operation is performed, for the received transmission signal, by a synchronous detection with the use of a leakage carrier created due to the DC offset and included in the transmission signal.

QAM with DC bias in one channel

A data transmitting-receiving system includes a transmitter unit, a transmission line, and a receiver unit. The transmitter unit includes a first memory circuit receiving first digital input data to be transmitted, a first digital/analog (D/A) converter, a second memory circuit receiving second digital input data to be transmitted, and a second D/A converter. The first and second memory circuits can provide a first digital correction output and a second digital correction output, respectively. The first and second digital correction outputs are composed of both an own-side correction output connected to an own-side channel route and an other-side correction output connected to an other-side channel route.

Growing community of inventors

Kawasaki, Japan

Eisuke Fukuda