Nec Corporation

Kenichi Hosoya

Kenichi Maruhashi

Naoyuki Orihashi

Yasuyuki Suzuki

Hiroyuki Okada

Shuya Kishimoto

Yasushi Amamiya

Shigeki Wada

In a phased array antenna radio communication apparatus including a plurality of antennas, a radio communication apparatus is provided which can reduce an influence of the local leak signals on the radiation direction of transmission signals. Local signal phase shifters-to-are used to control phases of local signals to be input to quadrature modulators-to-, and baseband signal phase shifters-to-are used to control phases of baseband signals to be input to the quadrature modulators-to-. The radiation direction of the local leak signals to be sent from transmission antennas-to-can be controlled by the local signal phase shifters-to-, and the radiation direction of the transmission signals can be controlled by both of the local signal phase shifters-to-and the baseband signal phase shifters-to-

Radio communication apparatus, transmitter, and radio communication method

A communication device(transceivers) transmits a training signal from its own transmitting antenna while performing beam scanning, and a communication device(transceivers) receives this training signal in a state where a quasi-omni pattern is generated in its own receiving antenna. Further, the devicetransmits a training signal in a state where a quasi-omni pattern is generated in the transmitting antenna, and the devicereceives this training signal by the receiving antenna while performing beam scanning. The deviceanddetects, from respective reception results, transmitting-antenna-setting candidates of the deviceand receiving-antenna-setting candidates of the device, and determines antenna-setting pairs (combinations of antenna-setting candidates). The above-described processes are also performed for a receiving antenna of the deviceand a transmitting antenna of the device. The deviceandcommunicates by using the obtained antenna-setting pairs. In this way, when radio communication is performed by using beam forming, the time necessary for finding and setting a beam direction is reduced, thereby reducing the transmission-disconnected time.

Control method of radio communication system, radio communication system, and radio communication apparatus

When communication is to be performed between communication devices having a directivity control function, a plurality of antenna-setting pairs available for the communication are stored by an initial training, and the communication is started by using one of the plurality of antenna-setting pairs. When the communication quality is deteriorated, firstly, a training signal is transmitted while successively setting each one of the plurality of antenna-setting candidates determined in the initial training in a transmitting antenna of one of the communication devices (), and the training signal is received in a state where a quasi-omni pattern is generated in a receiving antenna of the other communication device (). In this way, in radio communication performing beam forming, it is possible to ensure the time synchronization between the communication devices when communication is disconnected or communication quality is deteriorated due to shielding or the like.

To suppress adverse effects caused by side lobes of an antenna array when an AWV to be used for communication is determined based on a transmission/reception result of a training signal. A first transceiver generates a fixed beam pattern and transmits a training signal. In that state, a second transceiver receives the training signal while scanning for the main beam direction, and thereby determines a plurality of direction of arrivals (DOAs). Next, the second transceiver receives the training signal in a state where the signal receptions from the plurality of DODs are restricted one by one (e.g., a null direction or a direction close to the null direction is fixed in the DOA), and calculates the change of the signal characteristics from that obtained in the first reception. The transceivers obtain and use at least one AWV having the main beam direction or a sub-beam direction close to the main beam pointing to one of the plurality of DOAs except for the DOA for which the change is lower than a predefined threshold.

Control method of wireless communication system, wireless communication system, wireless communication apparatus, and adjustment method of array weight vector

A communication device(transceivers) transmits a training signal from its own transmitting antenna while performing beam scanning, and a communication device(transceivers) receives this training signal in a state where a quasi-omni pattern is generated in its own receiving antenna. Further, the devicetransmits a training signal in a state where a quasi-omni pattern is generated in the transmitting antenna, and the devicereceives this training signal by the receiving antenna while performing beam scanning. The deviceanddetects, from respective reception results, transmitting-antenna-setting candidates of the deviceand receiving-antenna-setting candidates of the device,and determines antenna-setting pairs (combinations of antenna-setting candidates). The above-described processes are also performed for a receiving antenna of the deviceand a transmitting antenna of the device. The deviceandcommunicates by using the obtained antenna-setting pairs. In this way, when radio communication is performed by using beam forming, the time necessary for finding and setting a beam direction is reduced, thereby reducing the transmission-disconnected time.

A channel response matrix is obtained by performing a training process between a transmitterand a receiverto obtain optimal signal phases of the antenna array. Next, a singular-value decomposition (SVD) process is performed to decompose the channel response matrix into a correlation matrix and eigenvalues. Next, a diagonal matrix having square roots of the eigenvalues as its components is obtained. Next, all but one of diagonal components included in the diagonal matrix are replaced with zeros, and optimal setting of the amplitudes and phases of signals to be applied to the antenna array (antenna weight vector) for use in wireless communication between the transmitter and the receiver is obtained based on a channel response matrix that is reconstructed by using the component-replaced diagonal matrix. In this way, when wireless communication is implemented by performing beam forming, the time necessary to find and set a beam direction can be reduced.

Control method of wireless communication system, wireless communication system, transmitting apparatus, and receiving apparatus

To suppress an adverse effect caused by side lobes of an antenna array when determining an AWV to be used in communication. A first communication device transmits/receives a training signal while scanning a beam pattern, and a second communication device receives/transmits the training signal with a fixed beam pattern. A primary DOD/DOA in the first communication device is determined based on the transmission/reception result of the training signal. Then, second round training is performed. In this point, the first communication device transmits/receives the training signal while scanning a beam pattern in a state where transmission to the primary DOD or reception from the primary DOA is restricted. A secondary DOD/DOA is determined based on the result of the second round training. An AWV corresponding to the primary DOD/DOA and an AWV corresponding to the secondary DOD/DOA are selectively used in communication between the first and second devices.

Control method of wireless communication system, wireless communication system, adjustment method of array weight vector, and wireless communication device

A first device transmits a training signal with a fixed beam pattern, a second device receives the training signal while scanning a beam direction, and then it obtains first AWVs each having a main beam or sub-beam beam direction in an incoming direction in the second device. Next, the first device transmits a training signal while scanning a beam direction, the second device receives the training signal with a fixed beam pattern, and then it obtains second AWVs each having a main beam or sub-beam direction in an emitting direction in the first communication device. The roles of these two devices are interchanged and similar processes are performed in order to obtain third and fourth AWVs, and then one of first AWV combinations from first and second AWVs and one of second AWV combinations from third and fourth AWVs are used for wireless communication between these devices.

Method of controlling wireless communication system and wireless communication system

A method of controlling a wireless communication system including a plurality of communication devices is disclosed. In the method, firstly, one of the communication devices establishes a fixed beam pattern and transmits a training signal, and another communication device receives the training signal while scanning a beam direction by changing the AWVs of an antenna array. Next, it obtains a data string describing a relation between an incoming direction and a received-signal characteristic at the other communication device based on a reception result of the training signal. Then, it obtains first AWVs with which a beam is formed in a plurality of incoming directions of the received signal based on the data string. The roles of these two communication devices are interchanged and similar processes are performed in order to obtain second AWVs, and then one of AWV combinations combining first and second AWVs are used for wireless communication between these communication devices.

A voltage-controlled oscillator is provided with inductorarranged between a power supply and a ground; and a variable capacitive section 56 that configures a resonator circuit with inductor. Variable capacitive section 56 is provided with first and second control terminals 1, 2 to which a voltage is applied to change the capacitance. Variable capacitive section 56 includes first variable capacitive elementwherein one terminal is connected to first control terminal 1 and the other terminal is connected to second control terminal 2; and second variable capacitive elementwherein one terminal is connected to second control terminal 2 and the other terminal is connected between the inductor and the ground.

Voltage-controlled oscillator, phase-locked loop circuit and clock data recovery circuit

A voltage-controlled oscillator comprises an inductor and a group of variable capacitance elements forming a resonance circuit. The group of variable capacitance elements includes first and second variable capacitance elements connectable in parallel and having mutually different absolute values of a ratio of control-voltage sensitivity to capacitance. The first and second variable capacitance elements both have a first end supplied with a control voltage for controlling resonance frequency of the resonance circuit and have a second end selectively connected to the inductor by a band selection signal for deciding a band in which the resonance frequency exists.

Voltage-controlled oscillator

A voltage controlled oscillator of the present invention includes power supply terminal (), control terminal () for controlling an output frequency, output terminals (), cross-coupled transistors (), capacitances (), LC tanks (), resistor (), grounding capacitance () and center frequency control circuit (). Center frequency control circuit () includes resistors (), grounding capacitance (), center frequency control terminal () for controlling a center frequency of the output frequency, and voltage-divider circuit (). Resistors () are connected to the base terminals of cross-coupled transistors (), the other ends of resistors () are connected to each other, and, to this connecting point, one end of grounding capacitance () and one end of voltage-divider circuit () are connected. The other end of voltage-divider circuit () is connected to center frequency control terminal ().

Voltage controlled oscillator and frequency control method of the voltage controlled oscillator

An object is to suppress a reflection loss in any desired frequency band outside a required band, without affecting circuit characteristics in the required frequency band. The output impedance of a circuit in a specified frequency band is transformed into a high impedance by a transmission line. A resistance grounding circuithaving a frequency selectivity is connected in parallel. The resistance grounding circuitis constructed of a resistorwhich has a resistance close to a load resistance, a capacitance C which is selected so as to satisfy an equation Im[tan h{&#x3b3;(&#x3bb;/2&#x2212;&#x3b4;)}]=&#x2212;&#x3c9;CZat an angular frequency &#x3c9;included in the frequency band, and a (&#x3bb;/2&#x2212;&#x3b4;)-long end-open stub.

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Tokyo, Japan

Kenichi Hosoya