Nippon Telegraph and Telephone Corporation

Ntt Corporation

Daisuke Goto

Kiyohiko Itokawa

Yasuyoshi Kojima

Fumihiro Yamashita

Kazumitsu Sakamoto

Yosuke Fujino

Koichi Harada

Izumi Urata

Munehiro Matsui

Yutaka Imaizumi

Hiroki Shibayama

Masaki Shima

Yasushi Takatori

Koichi Ishihara

Hirantha Abeysekera

Toshiro Nakahira

Yasuhiko Inoue

Takafumi Hayashi

Shoko Shinohara

Kento Yoshizawa

Junichi Abe

Tomoya Kageyama

In a wireless communication system in which a relay apparatus provided in a mobile object wirelessly communicates with a plurality of communication apparatuses placed at different locations, the relay apparatus includes a receiver that receives a signal transmitted from each of the plurality of communication apparatus, the signal including position information indicating a position of each communication apparatus, a measurement unit that measures a congestion level of communication, a control unit that divides a communication target area into a plurality of small areas in accordance with the positions of the plurality of communication apparatuses and the congestion level of communication and generates area information indicating a position of each of the small areas, and a transmitter that sequentially transmits a plurality of pieces of the area information when the relay apparatus is positioned in a range in which the relay apparatus can communicate with the communication apparatuses, and each communication apparatus includes a storage unit that stores transmission data, a receiver that receives the area information, a control unit that determines whether a position of the communication apparatus is included in the small area in accordance with the area information, and a transmitter that transmits a signal including the transmission data and position information indicating a position of the communication apparatus to the relay apparatus when the position of the communication apparatus is included in the small area.

Wireless communication system, communication apparatus, wireless communication method and communication program

A wireless communication system includes: one or more first communication devices located in one or more small areas among a plurality of small areas into which a communication target area is divided; a relay device; and a second communication device, in which the relay device includes: an antenna drive unit that drives one or more antennas to scan the plurality of small areas with one or more beams while emitting the beams to the communication target area, the beams each having an emission range narrower than the communication target area; a reception unit that acquires, from the antennas, a first wireless signal transmitted from the first communication devices located in the emission range; and a transmission unit that transmits a second wireless signal depending on the first wireless signal to the second communication device.

Wireless communication system, relay apparatus, wireless communication method and program

An antenna orientation deciding method in a wireless communication system that has a communication device provided with an antenna having directionality and a relay device that travels, includes a deciding step of deciding an orientation at which the directionality of the antenna as to the relay device is optimal, on the basis of position information of the communication device, orbit information of the relay device, and information relating to orientation of directionality of the antenna.

Antenna direction determining method, wireless communication system and communication device

A wireless communication system includes one or more communications apparatuses, and a relay device, which is mobile, wherein the relay device includes a transmission unit adapted to transmit a channel change signal to the one or more communications apparatuses, the channel change signal containing channel information that indicates results corresponding to interference levels of a plurality of channels in a frequency band available for use in uplink transmission from the one or more communications apparatuses to the relay device and specifying information used to specify a communications apparatus subject to channel change, and the one or more communications apparatuses include a channel set unit adapted to set a channel having an interference level lower than a threshold as a channel to be used for communications with the relay device when the specifying information contained in the channel change signal is applicable.

Wireless communication system, relay device, and channel setting method

A signal acquisition unit acquires a reception signal received by a reception device from a transmission device that moves relative to the reception device. A compensation unit compensates for a Doppler shift of the reception signal on the basis of a possibility of a change amount of the Doppler shift. A search unit changes a value of a possibility of the change amount of the Doppler shift in a case where a bandwidth having a power equal to or greater than a predetermined threshold in frequency components of the reception signal after the compensation is larger than a predetermined value.

Doppler shift compensation apparatus and doppler shift compensation method

A receiving unit receives a signal from a transmission terminal. A capacity specifying unit specifies a channel capacity related to wireless communication with a base station. A data generation unit generates waveform data representing the received signal. A data size of the waveform data increases as the channel capacity increases. A transmission unit transmits the waveform data to the base station.

Relay apparatus and relay method

There is provided a control device of a wireless communication system including the control device that is installed on a moving object and moves, a first communication device that transmits a desired signal to the control device by a first wireless method, a second communication device that transmits an interference signal interfering with the desired signal by a second wireless method, and one or more third communication devices, the control device including: a reception unit that acquires a wireless signal including a reference signal transmitted from the third communication device in the vicinity of the second communication device by a third wireless method and a desired signal transmitted from the first communication device by the first wireless method; an extraction unit that extracts the reference signal from the wireless signal based on the third wireless method; an estimation unit that estimates a propagation channel between the third communication device and the control device based on the reference signal; and a beam control unit that directs a null of a reception beam in an arrival direction of the reference signal based on the propagation channel.

Control apparatus and control method

A signal acquisition unit acquires a reception signal received by a reception device from a transmission device that moves relative to the reception device. A bandwidth specifying unit specifies a reception bandwidth that is a bandwidth of the reception signal. A shift specifying unit specifies a change amount of a Doppler shift per time on the basis of a difference between a bandwidth of a transmission signal in the transmission device and the reception bandwidth. A compensation unit compensates for a change of the Doppler shift of the reception signal on the basis of the change amount specified.

A communication device includes an antenna, a support portion, an actuator, a floating body, a sensor, and a control device. The antenna has a rod-shaped element. The instruction unit supports the antenna rotatably about a rotation axis orthogonal to an extending direction of the element. The actuator rotates the antenna about the rotation axis. The floating body supports the support portion and floats on water. The sensor measures a physical quantity related to inclination of the support portion. The control device includes a measurement value acquisition unit and a rotation control unit. The measurement value acquisition unit acquires a measurement value of the sensor. The rotation control unit drives the actuator on the basis of the measurement value to match a direction in which a change in the inclination is smallest with an extending direction of the antenna.

Wireless communication apparatus and control method

In a wireless communication system in which a relay device provided on a mobile object communicates wirelessly with a plurality of communication devices present in places different from each other, each of the communication devices includes a communication device transmission unit which transmits test signals at a plurality of timings during a time frame when communication with the relay device is possible, a communication device reception unit which receives, from the relay device, communication situation information indicating communication situations at the plurality of timings, and a communication device control unit which controls the communication device transmission unit such that the communication device transmission unit communicates with the relay device at one of the plurality of timings, the communication situation of which is good and which is identified on the basis of the communication situation information, and the relay device includes a relay device reception unit which receives the respective test signals at the plurality of timings, a measurement unit which measures the respective communication situations at the time of reception of the test signals at the plurality of timings, a relay device control unit which generates the communication situation information on the basis of the communication situations, and a relay device transmission unit which transmits the communication situation information to the communication device during a time frame when communication with the communication device is possible.

Wireless communication system, communication apparatus, relay apparatus, communication timing determination method and computer program

A wireless communication system includes: a measurement unit that measures a signal level of an analog signal corresponding to a received radio signal; a first output unit that amplifies an amplitude of the analog signal and extracts an analog signal with a desired frequency band from the analog signal with the amplified amplitude; a second output unit that extracts an analog signal with a desired frequency band from the analog signal and amplifies an amplitude of the extracted analog signal; and a switching control unit that inputs the analog signal corresponding to the received radio signal to the first output unit when the signal level of the analog signal other than the desired frequency band is less than a threshold, and inputs the analog signal corresponding to the received radio signal to the second output unit when the signal level of the analog signal other than the desired frequency band is equal to or greater than the threshold.

Wireless communication system, relay apparatus and wireless communication method

A first offset compensator configured to compensate for frequency offsets occurring during communications between a plurality of communication devices and a relay device, wherein when the first offset compensator is provided on the relay device, the first offset compensator gives a statistical frequency offset obtained from a statistic of a plurality of frequency offsets occurring during communications between respective ones of the plurality of communication devices and the relay device to a receiver configured to receive wireless signals transmitted from respective ones of the plurality of communication devices, and when the first offset compensator is provided on each of the plurality of communication devices, the first offset compensator gives a frequency offset occurring during communications between the communication device provided with the first offset compensator and the relay device to a transmitter configured to transmit wireless signals to the relay device.

Wireless communication system, relay device, communication device, and wireless communication method

A transceiver includes: a plurality of antennas that performs communication with one or more first communication apparatuses serving as reference at the time of forming a communication area and a second communication apparatus located near the one or more first communication apparatuses; a channel estimation unit configured to perform channel estimation for each of the one or more first communication apparatuses based on a known reference signal transmitted from the one or more first communication apparatuses; and an antenna control unit configured to control the plurality of antennas using an estimation value obtained by the channel estimation to form a beam having directivity in a direction in which the one or more first communication apparatuses are located. According to the control of the antenna control unit, the plurality of antennas forms a transmission beam in a communication area formed in a predetermined range including the one or more first communication apparatuses or forms a reception beam for receiving a signal transmitted from the second communication apparatus located in the communication area.

Transceiver, wireless communication system and wireless communication method

An acquisition unit acquires a plurality of signals received by a plurality of antennas included in a wireless communication device that moves in a predetermined orbit above a celestial body. A parameter determination unit determines a synthesis parameter of the plurality of signals according to the position of a transmission terminal provided on the celestial body, the orbit, and the reception time of the plurality of signals. A synthesis unit synthesizes a transmission signal of the transmission terminal according to the plurality of signals and the synthesis parameter.

Signal processing apparatus, wireless communication system and signal processing method

A plurality of control signals transmitted in individual frequency bands by a moving transmission station via a plurality of transmission antennas and a plurality of data signals transmitted in a common frequency band by the transmission station via the plurality of transmission antennas in synchronization with the control signals are received by each of a plurality of antennas disposed at different positions. Based on symbol timings of the control signals received by the antenna, a sampling rate error between the plurality of control signals transmitted by the plurality of transmission antennas, respectively, is compensated for. Based on the control signals subjected to the sampling rate error compensation, frame timings of the plurality of data signals transmitted by the transmission station via the plurality of transmission antennas are synchronized. Based on the control signals subjected to the sampling rate error compensation, channels for the plurality of data signals transmitted by the transmission station via the plurality of transmission antennas are estimated. The plurality of data signals with the frame timings synchronized, for the estimated channels are equalized.

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Musashino, Japan

Daisuke Goto