Fujitsu Corporation

Atsushi Honda

Yoji Ohashi

Kaoru Yokoo

Yasuyuki Oishi

Yuuta Nakaya

Mitsuhiro Azuma

Ichirou Ida

Toru Maniwa

Hiroyoshi Ishikawa

Alexander Nikolaevich Lozhkin

Toshio Kawasaki

Michiharu Nakamura

Yuichi Utsunomiya

Teruhisa Ninomiya

Tomoya Ota

Takenori Ohshima

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 wireless communication device includes a delay circuit to generate four or more delay signals, an amplifier circuit amplifying the four or more delay signals to generate four or more amplified delay signals, and a combiner circuit combining at least two amplified delay signals to generate an output signal, a second phase of a second amplified delay signal is between a first phase of a first amplified delay signal and a third phase of a third amplified delay signal, gains of the amplifier circuit for the four or more delay signals are controlled such that the output signal is generated by combining the first amplified delay signal and the third amplified delay signal, and a phase of the output signal is between the first phase of the first amplified delay signal and the third phase of the third amplified delay signal.

Wireless communication device, control method of wireless communication device and phase shifter

A wireless device includes a receiver that receives a first radio signal transmitted from a first communication device and a second radio signal transmitted from a second communication device, and a processor that detects a first arrival direction which is a direction opposite to a propagation direction of the received first radio signal and a second arrival direction which is a direction opposite to a propagation direction of the received second radio signal and generates a first signal for guiding the wireless device so as to be located on a straight line that extends in a propagation direction of the second radio signal received by the first communication device based on the detected first and second arrival directions.

Wireless device, control method, recording medium, and display method

A first apparatus receives, from a second apparatus, a signal including information on first time-periods each associated with an occupancy rate, using a wireless channel. The first time-periods each indicate a time-period during which data are scheduled to be collected by the second apparatus, and the occupancy rate indicates a ratio of a duration-time during which data are actually collected by the second apparatus using the wireless channel, to the each first time-period. The first apparatus, based on the occupancy rate and the received power of the first signal, calculates interference values each indicating a degree of interference caused by a radio wave from the second apparatus during the each first time-period, and acquires, based on the calculated interference values, second time-periods during which data are scheduled to be collected by the first apparatus, and collects data from a node apparatus during the third time-periods using the wireless channel.

System and method for collecting data using a wireless communication channel

A wireless sensor network system includes a plurality of sensor devices each having a non-directional antenna, and an information gathering apparatus having an adaptive array antenna and gathering information detected by the plurality of sensor devices. Each sensor device includes a transmitter to transmit a transmission request for connecting to the information gathering apparatus. The information gathering apparatus includes, a first directivity-changing section that, when the information gathering apparatus receives a transmission request from an unconnected sensor device, performs one of changing the adaptive array antenna to be non-directional, and changing a directivity of the adaptive array antenna, and that receives a signal transmitted from one of the unconnected sensor device and the unconnected sensor device and a connected sensor device, and a second directivity-changing section to change the directivity in accordance with a reception state of the signal.

Wireless sensor network system, information gathering apparatus, sensor device, and connection method for use in wireless sensor network

A radio device including a plurality of antennas transmitting and receiving a signal a reception band filter which controls a pass frequency band a measuring circuit which measures a reception level of the signal received by each of the plurality of antennas in a preamble in the signal received through the reception band filter an antenna switch which switches the plurality of antennas based on a measurement result from the measuring circuit and a processor which controls transmission and reception of the signal of the radio device and a pass frequency band of the reception band filter, and which transmits, based on a packet density, an instruction for changing the preamble from a first data length to a second data length to the other radio device and for changing the pass frequency band of the reception band filter from a first band to a second band.

Radio device, communication control method, and radio communication system

A variable directional antenna by means of a microstrip antenna and reactance change. The variable directional antenna has a structure to reduce sidelobes occurring when an element interval is reduced, and is structured in a three-element plane, having a feeding element and non-feeding elements provided at both sides of the feeding element. Each of the non-feeding elements provided at both sides of the feeding element has two split non-feeding elements two-divided into sizes of 1:2 in the lateral direction. The split non-feeding element divided into the size 1 is provided closer to the feeding element, and a reactance variable part is connected with the split non-feeding element divided into the size of 2. Alternatively, each of the non-feeding elements provided at both sides of the feeding element has two split non-feeding elements two-divided into sizes of 2:1 in the lateral direction. The split non-feeding element divided into the size 2 is provided closer to the feeding element, and the reactance variable part is connected either with the split non-feeding element divided into the size of 2 or the split non-feeding element divided into the size 1.

Variable directional antenna

A phase tracking circuit includes a divider part dividing an input signal that includes data sub-carriers and pilot sub-carriers into groups so that each of the groups includes at least one of the pilot sub-carriers, and a correcting part correcting phases of data sub-carriers of the input signal included in one of the groups on the basis of an amount of phase rotation of the at least one of the pilot sub-carriers included in the above one of the groups.

Phase tracking circuit and radio receiver using the same

In a wireless communication apparatus in a time division duplex system, a transmission signal generation unit generates a transmission signal. A power amplifying device amplifies the generated transmission signal. A control signal generation device generates a drain voltage control signal for control of the drain voltage of the power amplifying device, and a gate voltage control signal for control of the gate voltage of the power amplifying device. The switch unit switches off the drain power supply of the power amplifying device during reception in the time division duplex system according to the drain voltage control signal. In addition, the power amplifying device sets a higher gate voltage during reception in the time division duplex system higher than during transmission according to the gate voltage control signal.

Wireless communication apparatus, power amplifier control method, and power amplifier control apparatus

A disclosed group delay characteristic correcting device corrects group delay characteristics of an analog low-pass filter used to remove aliasing of a digital-analog converter or an analog-digital converter. The group delay characteristic correcting device includes a digital signal processing unit configured to have an all-pass phase circuit at a stage previous to the digital-analog converter or at a stage subsequent to the analog-digital converter so as to correct the group delay characteristics of the analog low-pass filter.

Group delay characteristic correcting device and group delay characteristic correcting method

At least two antennas are selected from a plurality of antennas which consist of at least two antennas having polarization characteristics or directivities different from one another, and which are arranged such that spatial fading correlations between the antennas are low, and a multiple input multiple output communication is conducted by using the selected antennas.

Antenna apparatus for multiple input multiple output communication

The present invention provides a wireless terminal apparatus, including a reception unit for receiving a multi-carrier signal generated by applying an N-point (where N is a natural number) inverse fast Fourier transform (IFFT) to a plurality of sub-carriers to which transmission information for a plurality of wireless terminal apparatuses is allocated; a fast Fourier transform unit for extracting a plurality of the sub-carriers from the multi-carrier signal; a thin-out unit, being placed at the front stage of the fast Fourier transform unit, capable of changing, from the N points, a sampling number of the multi-carrier signals which are digitalized; and a judgment unit for discerning, based on sub-carrier allocation information accompanying the multi-carrier signal, whether or not the sub-carrier of another wireless terminal apparatus overlaps with that of the wireless terminal apparatus itself in the case of changing the sampling number from the N points, and determining a sampling number for the thin-out unit.

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Kawasaki, Japan

Atsushi Honda