Nippon Telegraph and Telephone Corporation

Kazumitsu Sakamoto

Yohei Katayama

Hiroyuki Fukumoto

Yosuke Fujino

Takayuki Mizuno

Etsushi Yamazaki

Takuya Ohara

Kento Yoshizawa

Takeshi Kinoshita

Daisuke Goto

Kiyohiko Itokawa

Yasuyoshi Kojima

Kenji Suzuki

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 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 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

A station installation designing assistance device that divides a service providing area into a plurality of areas, and performs station installation designing for the plurality of areas in parallel, the station installation designing assistance device including: an area dividing unit that divides an entirety of the service providing area into a plurality of areas that are each composed of a predetermined number of small areas; a small area specifying unit that specifies a small area number that identifies a small area in each of the areas, where the same number is given to the small area in each of the areas; and a station installation location selecting unit that selects, for each of the plurality of areas, a plurality of station installation locations from among station installation location candidates that are present in the small area specified by the small area specifying unit.

Station placement designing assistance apparatus, station placement designing assistance method and program

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 quality calculation unit () of a base station placement design device () calculates communication quality of each terminal in a case where a base station is installed at a base station placement candidate location for a plurality of base station placement candidate locations. An aggregation unit () aggregate the number of terminals whose communication quality calculated by the communication quality calculation unit () is equal to or greater than a threshold value for each of the plurality of base station placement candidate locations. A base station placement location selection unit () selects a base station placement location from among the plurality of base station placement candidate locations, based on the number of terminals aggregated by the aggregation unit () for each of the plurality of base station placement candidate locations.

Station placement designing apparatus, station placement designing method and program

A communication control device that transmits a packet to be transmitted to a terminal to a base station that performs wireless communication with the terminal, includes: a terminal classification unit that classifies, on the basis of a magnitude of radio wave interference from a base station different from a neighboring base station, a plurality of the terminals into a first terminal set and a second terminal set that is relatively larger in the magnitude of radio wave interference than the first terminal set; and a transmission unit that transmits, in a case where packets destinations of which are terminals belonging to the first terminal set are to be transmitted to respective neighboring base stations of the terminals, the packets at the same timing and transmits, in a case where packets destinations of which are terminals belonging to the second terminal set are to be transmitted to respective neighboring base stations of the terminals, the packets at timings different from each other.

Communication control apparatus, communication control method and program

A station installation designing assistance device that divides a service providing area into a plurality of areas, and performs station installation designing for the plurality of areas in parallel, the station installation designing assistance device including: an area dividing unit that divides an entirety of the service providing area into the plurality of areas; a station installation priority determining unit that determines, for each of the plurality of areas, station installation priorities of station installation location candidates that are present in the area; and a station installation priority adjusting unit that adjusts the station installation priorities determined by the station installation priority determining unit, based on a degree of overlap of cells formed as a result of base stations being installed in station installation location candidates in the areas, respectively.

An arrival rate estimation device includes an average received power calculation unit that calculates an average received power for each mesh that constitutes an area, with respect to each of a plurality of base stations and each of a plurality of antennas included in each of the base stations and an arrival rate estimation unit that calculates a communication arrival rate by substituting the average received power into a cumulative distribution function of an instantaneous received power value, and based on the calculated communication arrival rate, calculates a communication arrival rate while giving consideration to a site diversity effect and an antenna diversity effect, the cumulative distribution function being obtained from a probability density function of an amplitude that instantaneously changes due to Rayleigh fading.

Arrival rate estimation apparatus, arrival rate estimation method and program

A radio terminal accommodation determination device includes: an average received power calculation unit for calculating an average received power for each mesh constituting an area; an interfering signal power CDF creation unit for creating a cumulative distribution function of all interfering signal powers; an intended signal power PDF creation unit for creating a fourth probability density function indicating a probability density function of an intended signal power; and a communication success rate estimation unit for calculating, for each base station, a communication success rate of the intended terminal based on the cumulative distribution function and the fourth probability density function.

Wireless terminal accommodation determination apparatus, wireless terminal accommodation determination method and program

A monitoring system comprises a monitoring agent that keeps information related to a communication status of a low-power terminal that communicates under low power, and a monitoring device that monitors the status of the low-power terminal. The monitoring device includes a requesting unit that requests information related to the communication status of the low-power terminal. The monitoring agent includes a response generation unit that generates a response to the request from the monitoring device on a basis of the information related to the communication status of the low-power terminal, and a transmission unit that transmits the response to the monitoring device.

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Tokyo, Japan

Kazumitsu Sakamoto