Nippon Telegraph and Telephone Corporation

Kento Yoshizawa

Yohei Katayama

Takayuki Mizuno

Etsushi Yamazaki

Takuya Ohara

Kazumitsu Sakamoto

Takeshi Kinoshita

Takafumi Fujita

Hideya So

Yusuke Asai

Hiroyuki Fukumoto

Yosuke Fujino

Daisei Uchida

Ryo Miyatake

Daisuke Goto

Kiyohiko Itokawa

Yasuyoshi Kojima

Fumihiro Yamashita

Kazunori Akabane

Shigeru Teruhi

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 synchronization method includes: a first step of transmitting a query command a plurality of times to a communication device configured to perform time synchronization with a base station device connected to a mobile communication network, the query command requesting time information expressed in a first unit, the first unit being lower in accuracy than accuracy of the time synchronization established by the communication device; a second step of determining timing at which the time information obtained in response to the query command is updated; a third step of determining timing to transmit a next query command, based on the timing at which the time information is updated; and a fourth step of acquiring time information with higher accuracy than the first unit, based on time information obtained in response to the query command transmitted at the third step.

Synchronization method and information apparatus

A switching instructor outputs a beacon light selection notification signal when a optical transceiver transmits a optical wireless signal of a beacon light and outputs a signal light selection notification signal when the optical transceiver transmits the optical wireless signal of the signal light. A spatial light modulator controller performs switching of a control signal given to each of the plurality of pixels of a spatial light modulator to: cause a phase delay in light received by each of the plurality of pixels of the spatial light modulator when the switching instructor outputs the beacon light selection notification signal and cause a phase delay in light received by each of the plurality of pixels of the spatial light modulator when the switching instructor outputs the signal light selection notification signal.

Optical wireless communication device and optical wireless communication method

A communication device includes: a light output unit for outputting light; a light splitting unit for splitting the light output by the light output unit into a plurality of split beams; and a plurality of spatial optical communication units provided in correspondence to the plurality of split beams, wherein the spatial optical communication units respectively transmit a corresponding split beam which is input from the light splitting unit to a partner communication device across space.

Communication apparatus and optical communication system

A phase difference distribution estimation method includes: receiving an optical signal via a space and detecting a phase of the optical signal; calculating characteristic values related to characteristics of the atmosphere through which the optical signal propagates from the optical signal received in the receiving; estimating a phase difference distribution of an optical signal received after a certain period of time, on the basis of the characteristic values calculated in the calculating; and controlling a phase of an optical signal in the receiving on the basis of the phase difference distribution estimated in the estimating.

Phase difference distribution estimation method and phase difference distribution estimation apparatus

In an optical wireless communication system including: an optical wireless communication apparatus that moves along with a first optical wireless station; and a second optical wireless station opposed to the first optical wireless station, the optical wireless communication apparatus includes at least one reference light transmitting unit that transmits reference light to the second optical wireless station with a position in front in a moving direction of the first optical wireless station defined as a transmission position, the second optical wireless station includes a reference light receiving unit that receives the reference light transmitted from the at least one reference light transmitting unit, an estimation unit that estimates an influence of atmospheric air on transmission of signal light based on a reception state of the reference light received by the reference light receiving unit, a compensation unit that performs compensation processing on the signal light based on the influence of the atmospheric air estimated by the estimation unit, and a signal light transmitting unit that transmits the signal light on which the compensation processing has been performed by the compensation unit in an arrival direction of the reference light.

Optical wireless communication system and optical wireless communication method

A communication method determination apparatus includes a comparison unit and an instruction unit. The comparison unit obtains a bit string of a portion of a physical header for synchronization from a wireless frame that includes the physical header for synchronization in which information for synchronization in a physical layer is set and a physical data portion in which data of a higher-level layer than the physical layer is set, and compares the obtained bit string with a bit string pattern specific to a communication method targeted for determination. The instruction unit performs communication method determination processing for determining whether or not the communication method targeted for determination is used for the wireless frame, based on a result of comparison. If it is determined that the communication method targeted for determination is not used for the wireless frame, the instruction unit changes the communication method targeted for determination, instructs the comparison unit to newly obtain a bit string of a portion that follows the obtained bit string, from the physical header for synchronization, and to compare the newly obtained bit string with a bit string pattern specific to the post-change communication method targeted for determination, and performs the communication method determination processing again.

Communication scheme determination apparatus, communication scheme determination method and program

A control device of the present invention is for provision in a gateway device that includes multiple communication units that perform wireless communication with terminal devices using different communication methods. Based on communication unit individual information that is acquired from the communication units and includes information indicating at least characteristics of the communication methods of the communication units, operations of the communication units are scheduled so as to prevent the overlapping of periods in which the communication units perform signal transmission/reception with the terminal devices.

Control apparatus, control method, and control program

A wireless communication system includes three or more wireless communication apparatuses and a control apparatus, wherein the control apparatus includes a setting unit configured to determine, for each of a plurality of paths from a first one of the wireless communication apparatuses to a second one of the wireless communication apparatuses, a total product value being a result of computing a total product of arrival probabilities of radio frames of respective radio sections constituting the path and a search unit configured to select a path, among the plurality of paths, with the number of transmission times of the radio frame for each of the paths being a predetermined number of times or smaller and the total product value being a predetermined threshold or more.

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

A transmitter includes a first measurement unit configured to measure a radio wave environment between the transmitter and a receiver for an individual wireless resource, a transmission control unit configured to determine the wireless resource and a parameter on a basis of the measurement result of the radio wave environment, an encoder unit configured to perform distributed coding of the bit sequence on a basis of the parameter, and a transmission unit configured to transmit information representing the determined wireless resource and the distributed coded bit sequence, by using the determined wireless resource. The receiver includes a second measurement unit configured to measure the radio wave environment for the individual wireless resource, a reception control unit configured to estimate the parameter on a basis of the measurement result of the radio wave environment, a reception unit configured to receive the information representing the determined wireless resource and the distributed coded bit sequence, by using the determined wireless resource, and a decoder unit configured to decode the received bit sequence on a basis of the parameter.

Wireless communication system, communication method, transmitter and receiver

A wireless communication system includes a plurality of wireless communication apparatuses that transmit a wireless frame to a terminal, and a control apparatus, and the wireless communication apparatus transmits information representing the number of retransmissions of the wireless frame to the control apparatus, and the control apparatus acquires the information representing the number of retransmissions of the wireless frame, selects the wireless communication apparatus in accordance with the number of retransmissions, and causes the selected wireless communication apparatus to start transmitting the wireless frame.

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Musashino, Japan

Kento Yoshizawa