Fujitsu Corporation

Fujitsu Frontech Limited

Fujitsu Llimited

Masahiko Shimizu

Akira Ito

Tsuyoshi Hasegawa

Koji Matsuyama

Takashi Dateki

Hiroyuki Egawa

Takashi Yamagajo

Hideto Furukawa

Kazuyuki Ozaki

Takeshi Inoue

Manabu Kai

Makoto Yoshida

Tomonori Sato

Shunji Miyazaki

Yoji Sugawara

Kenichi Nishikawa

Masaaki Fujii

Daisuke Ogawa

Yusuke Kawasaki

A wireless communication apparatus outputs first and second beams, based on a weighting vector representing gain and/or phase weighting. The apparatus derives a weighting vector corresponding to a maximum eigen value of a matrix obtained by subtracting, from a first matrix representing a main lobe output power of the first beam, a matrix obtained by multiplying a second matrix representing a side lobe output power of the first beam to a reduction ratio for reducing the side lobe output power of the first beam interfering with a main lobe of the second beam. The apparatus determines whether or not a power ratio of the main lobe output power of the first beam with respect to the side lobe output power of the first beam is greater than a maximum SIR, and extracts the weighting vector when the power ratio is not larger than the maximum SIR.

Wireless communication apparatus and beam control method

A wireless communication device includes: a plurality of subarrays each including a plurality of antenna elements and an analog circuit configured to perform a given analog process on signals to be transmitted from or received by the antenna elements; and a processor that is connected to the subarrays. The processor executes a process including: estimating direction of arrivals from which signals transmitted from a plurality of terminals come; calculating maps based on trigonometric functions of angles representing the estimated direction of arrivals; generating a plurality of groups to which the terminals belong based on the calculated maps; assigning, to each of the groups, a combination of subarrays to generate directional beams that do not interfere with each other; and determining weighting coefficients to generate directional beams in directions of the terminals which belongs to each group by using the combination of subarrays assigned.

Wireless communication device and beam control method

A radio communication apparatus includes an estimating unit that estimates directions of arrival of signals transmitted by a plurality of respective users, a calculating unit that calculates a map as a trigonometric function of an angle representing each of the directions of arrival estimated by the estimating unit, a grouping unit that groups the users based on the maps calculated by the calculating unit, and a determining unit that determines a weight coefficient for forming a directional beam steered to a user belonging to a group, for each group resultant of grouping performed by the grouping unit.

Radio communication apparatus and beam controlling method

A transmission method executed by a transmission device, the transmission method including performing a plurality of transmitting processes in accordance with a plurality of transmitting patterns, each of the plurality of transmitting processes including transmitting a plurality of signals for a plurality of directions in parallel by forming a plurality of beams corresponding to the plurality of directions, each of the plurality of transmitting patterns being defined a combination of directions to be transmitted in parallel, receiving a result of a determining from a reception device, the determining including determining whether or not, for each of a plurality of receiving processes, the at least one signal satisfies a predetermined condition, each of the plurality of receiving processes including receiving at least one signal transmitted from the transmission device, and selecting a transmitting direction for the reception device from the plurality of directions based on a result of the determining.

Beamforming for selecting a transmitting direction based on feedback from a reception device

A wireless communication apparatus includes a plurality of phase adjusters configured to adjust the phase of a digital baseband signal dfor k=1, 2, . . . , K (K is a natural number equal to or larger than one) and output a plurality of digital signals d, d, d(m is a natural number equal to or larger than two) having phases different from each other, an i-th converter configured to convert a signal obtained by synthesizing the digital signals d, d, . . . , dinto an analog signal afor i=1, 2, . . . , m, and a power supply circuit including a first stage circuit, a second stage circuit, . . . , an N-th stage circuit (N is a natural number equal to or larger than one).

Wireless communication apparatus, antenna directionality control method, and power supply circuit

An antenna device includes: a first antenna element configured to radiate first radio waves having a first plane of polarization; and a second antenna element configured to radiate second radio waves having a second plane of polarization orthogonal to the first plane of polarization, wherein ends of the first antenna element and the second antenna element located at mutually approaching sides are disposed in a positional relationship, and a phase deviation caused by an electromagnetic coupling based on the positional relationship is compensated and an electrical power is fed to the first antenna element and the second antenna element with a phase difference that causes a composite wave of the first radio waves and the second radio waves to form a circularly polarized wave.

Antenna device

A planar antenna includes: first and second conductors each of which forms a microstrip line in combination with a ground electrode, and which are arranged in parallel with each other on a substrate; a plurality of first resonators disposed between the first conductor and the second conductor which electromagnetically couple the first conductor at one longitudinal end of each of the first resonators to generate electric fields which are in phase with each other; and at least one second resonator disposed between the first conductor and the second conductor which electromagnetically couples the second conductor at one longitudinal end of the at least one second resonator to generate an electric field which is in phase with the electric fields generated by the plurality of first resonators, wherein the at least one second resonator is arranged alternately with the plurality of first resonators.

Planar antenna

A relay device that relays a wireless signal between a transmission device and a reception device, includes: a receiver that receives the wireless signal from the transmission device; a transmitter that transmits, to the reception device, the received wireless signal subjected to processing via a first protocol that amplifies the received wireless signal or a second protocol that decodes and re-encodes data contained in the received wireless signal; and a controller that switches between the first protocol and the second protocol using an evaluating index including a first evaluating value related to transmission environment between the transmission device and the relay device and a second evaluating value related to transmission environment between the relay device and the reception device.

Relay, method of relaying, and wireless communication system

A transmitter transmits a wireless signal produced by allocating data to component carriers for a plurality of communication bands, and a receiver receives the wireless signal and carries out a reception process for the received wireless signal with a predetermined reception sampling frequency are provided, and the component carriers are arranged at such positions that the data do not overlap with each other when the component carriers are superimposed on a frequency axis.

Wireless communication system, transmitter, receiver and wireless communication method

A radio communication device for executing a communication on the basis of a frequency division duplex, has a first antenna, a second antenna, a first receiver for receiving a first radio frequency signal via the first antenna, a second receiver for receiving the first radio frequency signal via the second antenna, a transmitter for transmitting a second radio frequency signal via the second antenna, a power measuring unit for measuring a first power of a component of the second radio frequency signal in a received signal received via the first antenna, and a control unit for controlling a reactance between the first antenna and the second antenna so as to lower an amount of coupling between the first antenna and the second antenna on the basis of the measured first power.

Radio communication device and method of controlling radio communication device

A first adjustment circuit adjusts an impedance of a first antenna, and a second adjustment circuit adjusts an impedance of a second antenna. A coupling reduction circuit reduces an amount of coupling of the first and second antennas. A first reception power measurement unit measures first reception power received from the first antenna, and a second reception power measurement unit measures second reception power received from the second antenna. A selection unit selects a circuit from among the first adjustment circuit, the second adjustment circuit, and the coupling reduction circuit. A circuit control unit controls the impedance of the selected circuit so that the value of the evaluation function proportional to the product of the first reception power and the second reception power becomes larger.

Communication device and control method

In an equalizer arranged in a wireless communication device: information on correlation in one or more first wireless signals is generated; a channel vector is generated on the basis of the one or more first wireless signals; an extended correlation matrix which contains a correlation matrix indicating the information on correlation and is extended so as to become a circulant matrix is generated; an extended channel vector is generated by extending the channel vector so that the extended channel vector contains elements of the channel vector and has rows the number of which is identical to the number of rows of the extended correlation matrix; and weight coefficients are calculated as a solution, in the frequency domain, of an equation expressed by the extended correlation matrix and the extended channel vector, where the solution is obtained by solving the equation.

Wireless communication device, equalizer, computer-readable medium storing program for obtaining weight coefficients in the equalizer, and process for obtaining weight coefficients in the equalizer

A transmission apparatus obtains, for each transmission to a reception apparatus, information on a per-bit transmission of a transmission bit string, and controls a per-bit transmission condition for a current transmission bit string such that a per-bit transmission quality of the transmission bit string approaches evenly based on cumulative information on the transmissions up to the last transmission.

Transmission method and transmission apparatus

Disclosed is a pilot multiplexing method in an Orthogonal Frequency Division Multiplexing (OFDM) system. Transmit data is transmitted by an OFDM signal through an OFDM scheme, pilot data is directly spread, and a spread-spectrum signal, which has been obtained by spreading, is transmitted in the same frequency band as that of the OFDM signal at the same time in superposition therewith or time-division multiplexed therewith. The spread-spectrum signal is a CDMA signal that has been obtained by spreading the pilot data by a prescribed spreading code.

Pilot multiplexing method and OFDM transceiver apparatus in OFDM system

A communication system that performs encoding and decoding for communication includes a transmitting apparatus and a receiving apparatus. The transmitting apparatus includes a turbo encoding unit including a first encoding unit that encodes an input signal and generates a first parity bit by bit-based encoding and n (n=1, 2, 3, . . . ) second encoding units that encode the input signal and generate second parity bits by bit-based encoding, and a symbol mapping unit that maps an output from the turbo encoding unit to a symbol by bit-based mapping operation and modulates the output. And the receiving apparatus includes a demodulating unit that demodulates a transmission signal, and a turbo decoding unit that performs turbo decoding on the demodulated signal by bit-based decoding.

Growing community of inventors

Kawasaki, Japan

Masahiko Shimizu