Nippon Telegraph and Telephone Corporation

Hitachi, Ltd.

Kenichi Kawamura

Yasushi Takatori

Keisuke Wakao

Shota Nakayama

Takatsune Moriyama

Daisuke Murayama

Akira Kishida

Tomoyuki Yamada

Hiroyuki Fujita

Hirantha Abeysekera

Munehiro Matsui

Yasunori Ono

Akira Yamagishi

Noriyuki Uchiyama

Yoshio Hamadate

Akiyoshi Inoki

Sadamu Saito

Hiroshi Nakamoto

Shouichi Yamamoto

Takahiro Asai

Masato Suzuki

Hiroshi Morita

Koichi Ishihara

Shinji Fujita

Takeo Ichikawa

Yoshifumi Morihiro

Kohei Yamaguchi

Satoshi Ichimura

Kohhei Aida

Li Lu

Jun Nukaga

Hisashi Morooka

Takahide Matsuo

Hiroshi Miyao

Hideki Ogata

Taku Oyama

A communication system includes a terminal configured to wirelessly communicate with a base station, a plurality of IoT terminals, and a control device. The control device includes a processor; and a memory that includes instructions, which when executed, cause the processor to execute the following steps: selecting an IoT terminal around a dead zone and transmitting a command of signal transmission to the selected IoT terminal. The selected IoT terminal includes a receiver configured to receive the command, and a transmitter configured to transmit a signal according to the command. The terminal receiving the signal transmitted from the selected IoT terminal performs a connection operation for avoiding the dead zone.

Communication system, connection designation control method, control apparatus and program

A specific signal in a radio communication system includes at least one of a synchronization signal and a reference signal. A first radio communication system performing radio communication in a first cell generates the specific signal based on a first seed and uses a first resource mapping pattern as a resource mapping pattern of the specific signal. A second radio communication system performing radio communication in a second cell that is adjacent to the first cell generates the specific signal based on a second seed and uses a second resource mapping pattern as a resource mapping pattern of the specific signal. When the first resource mapping pattern is identical to the second resource mapping pattern, the first seed and the second seed are set to be different from each other through sequence seed control.

Radio communication system, control method and control device for radio communication system, and radio communication system control program

A wireless LAN system where an interfering communication device is present around a base station device and a terminal device includes an interference control signal transmitter that transmits an interference control signal that causes the interfering communication device to wait for transmission, and an interference control signal management device that collects wireless environment information, sets wireless LAN communication between the base station device and the terminal device, which are protection targets, as protected communication, and causes the interference control signal transmitter to transmit an interference control signal that causes the interfering communication device to wait for transmission, and the interference control signal management device instructs the interference control signal transmitter to start transmitting the interference control signal when detecting a start of the protected communication and instructs the interference control signal transmitter to stop transmitting the interference control signal when detecting a stop of the protected communication.

Provide a wireless local area network (LAN) system, an interference control signal management device which are capable of limiting interference

An embodiment of the present invention is a local wireless communication system that emits a radio wave in a licensed band to form a wireless communication environment in a predetermined area. The system includes a base station configured to emit a radio wave, a plurality of sensors disposed along an edge of the area, and a control apparatus. The sensors each measure a radio field intensity of the radio wave emitted from the base station, and feed the radio field intensity back to the control apparatus via the base station. The control apparatus controls a transmission power of the radio wave from the base station to control the fed radio field intensity.

Local wireless communication system, radio field intensity control method, control device, and program

Provided is a wireless communication system that performs priority control by setting, depending on a type of transmission data, a channel use period during which exclusive use of a channel after a right to access the channel is acquired is permitted. The wireless communication system includes a measurement unit that measures quality measurement information related to a quality of wireless communication, a parameter setting unit that makes, when a latency in transmission of a prioritized frame due to transmission of a non-prioritized frame is not expected based on the quality measurement information measured by the measurement unit, settings such that the channel use period for the transmission of the non-prioritized frame is changed to be longer, and a MAC frame generation unit that generates a MAC frame which permits continuous transmission of the non-prioritized frames within the channel use period set by the parameter setting unit.

System and method for performing priority control in wireless communication

A wireless LAN system in which a BSS composed of one wireless LAN base station and a plurality of wireless LAN terminals belonging to the wireless LAN base station, is set as a unit, and a plurality of the BSSs using an identical channel respectively perform uplink multi-user transmission, includes a radio control apparatus that is connected to the wireless LAN base station of each of the plurality of the BSSs and a wireless LAN terminal of the plurality of wireless LAN terminals of each of the plurality of the BSSs, and configured to collect radio information indicating interference states of respective radio waves, group sets of BSSs of the plurality of the BSSs, which are outside of radio wave reachable ranges of each other, as one of a plurality of groups among the plurality of the BSSs using the identical channel according to the radio information, and perform control to shift a timing of channel access for performing uplink multi-user transmission between the plurality of groups.

Wireless LAN communication system, uplink control method, and wireless control device

Provided is a wireless LAN system in which an interference control signal transmitter that is provided in the surroundings of the wireless LAN base station and the wireless LAN terminal, and is configured to collect wireless environment information regarding the interfering AP/STA, and transmit, to the interfering AP/STA, an interference control signal that is to be used to set a transmission waiting period; and an interference control signal management device configured to collect the wireless environment information from the interference control signal transmitter, determine the interference control signal transmitter whose communication area includes the interfering AP/STA based on the wireless environment information, and control the determined interference control signal transmitter to transmit the interference control signal to be used to set the transmission waiting period that corresponds to a length of time of the communication between the wireless LAN base station and the wireless LAN terminal, wherein while the interfering AP/STA that has received the interference control signal sets the transmission waiting period, the wireless LAN base station and the wireless LAN terminal preferentially perform communication.

Wireless LAN system and interference control method

In a random access radio communication system configured to perform downlink communication from a radio base station to radio terminals by random access, the radio terminals include one or more low latency terminals requiring low latency and one or more non-low latency terminals not requiring low latency, and the low latency terminals and the non-low latency terminals are configured to be distinguished by service set identifiers (SSIDs). The random access radio communication system includes terminal assignment destination control unit of distinguishing the low latency terminals and the non-low latency terminals in accordance with the SSIDs and evenly distributing the terminals into a plurality of communication channels, and random access control unit of performing priority control on the low latency terminals and the non-low latency terminals for each communication channel so that the downlink communication in the low latency terminal satisfies a predetermined delay time.

Random access wireless communication system and random access wireless communication method

A wireless LAN communication device generates an MPDU by attaching a MAC header to transmission data, generates an A-MPDU subframe by attaching an MPDU delimiter to the MPDU, generates an A-MPDU by aggregating a plurality of A-MPDU subframes, and transmits the A-MPDU. The wireless LAN communication device includes: an MPDU duplicating means for determining whether or not transmission data is a redundancy target according to a required quality of the transmission data, determining that an MPDU generated from the transmission data determined to be a redundancy target is a redundant MPDU, and generating a duplicate MPDU by duplicating the redundant MPDU; and an A-MPDU generating means for generating an A-MPDU that includes the redundant MPDU and the duplicate MPDU.

Wireless LAN communication device and wireless LAN communication method

Provided is a wireless communication control method, in which a management server manages line selection of an unlicensed band/licensed band of a UE and manages parameters of the unlicensed band, including a control step of excluding the UE that uses the licensed band from an optimization target in an unlicensed band system and optimizing the parameters of the unlicensed band in consideration of existence of an STA and the UE that uses the unlicensed band, which is caused by the management server. Furthermore, a pattern when a total of a communication capacity in the unlicensed band and a communication capacity in the licensed band after the optimization of the parameters of the unlicensed band becomes high is adopted for the line selection of the UE, and the parameters of the unlicensed band after the optimization of the line selection are set for an AP, the STA, and the UE of the unlicensed band.

Wireless communication control method, wireless communication system, and management server

An AP and UE, which perform access control using CSMA/CA, perform a step judging an exposed level in transmission of the AP based on a congesting level in transmission, which is caused by a wireless station in defer transmission that is in a neighborhood of the AP; a step judging an exposed level in reception of the UE based on a congesting level in reception, which is caused by a wireless station in defer transmission that is in a neighborhood of the UE; and a step performing control which changes a channel of the AP, when the exposed level in transmission cannot satisfy expected quality of the AP, and performing control which changes a connected AP of the UE, or control which changes to other network, when the exposed level in transmission or in reception cannot satisfy required quality of the UE or the expected quality of the AP.

Wireless communication system and wireless communication control method

A stationary induction electrical apparatus includes a disc winding having a structure in which a flow path for a cooling medium is provided between coils where a low voltage is generated between shield wires, an L-shaped insulation barrier is provided between coils where a high voltage is generated between the shield wires, a horizontal portion of the L-shaped insulation barrier is provided so as to closely contact an upper surface or a lower surface of the disc coil, a tip end portion in an axial direction of the L-shaped insulation barrier is provided so as to closely contact an inner surface of the disc coil which is adjacent to a pressboard insulation cylinder, and a height of the tip end portion in the axial direction is lower than a thickness of one coil.

Stationary induction electrical apparatus

Electrical insulating paper according to an embodiment of the present invention is used while being immersed in electrical insulating oil, and includes a paper base material mainly containing cellulose, an adsorption layer formed on an entire surface of the paper base material by adsorption, and a moisture barrier layer formed by being chemically bonded to the adsorption layer. The moisture barrier layer includes an amphipathic molecule containing both a hydrophobic hydrocarbon group and a hydrophilic functional group in one molecule. The amphipathic molecule is chemically bonded to the adsorption layer via the hydrophilic functional group. The hydrophobic hydrocarbon group covers the surface of the paper base material.

Electrical insulating paper and stationary induction electrical apparatus using the same

The invention provides a stationary induction apparatus excellent in core vibration damping, being capable of realizing reduction in core excitation-noise. The stationary induction apparatus according to the invention includes a core made up of plural of core-legs formed by lamination of electromagnetic steel sheets, and a core-yoke formed by lamination of electromagnetic steel sheets to join the plural core-legs together; a core-tightening clasp for tightening a joint between the core-yoke and the core-legs, in the direction of the lamination of the electromagnetic steel sheets, to be secured, a winding, a tank, and an insulating sheet disposed between the core-tightening clasp and the core-yoke. Further, a concave hollowed-out part or a notched part is provided on the insulating sheet, positioned at a joint between the core-yoke and the core-leg, and a vibration insulator is disposed in the concave hollowed-out part or the notched part.

Stationary induction apparatus

Leakage fluxes from windings and leads of a stationary induction apparatus are confined within a tank. The stationary induction apparatus includes an electric functional units each including a winding and a core, a tank containing the electric functional units, high-voltage leads leading out from the windings, and low-voltage leads leading out from the windings. Magnetic shields are placed on the inner surface of a wall of the tank through which the high-voltage leads are drawn out of the tank, and a composite shield formed by combining nonmagnetic shields and magnetic shields is placed on the inner surface of a wall of the tank facing the low-voltage leads and is electrically short-circuited.

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Tokyo, Japan

Kenichi Kawamura