Nippon Telegraph and Telephone Corporation

Ntt Corporation

Tomoaki Ogawa

Hiroshi Sakamoto

Tomoki Murakami

Shinya Otsuki

Makoto Umeuchi

Masashi Iwabuchi

Hiroyuki Nakamura

Junichi Iwatani

Masayoshi Nabeshima

Riku Omiya

Yasushi Takatori

Masaru Miyamoto

Masamichi Hosoda

Tadashi Mori

Yasushi Hanakago

Yoghitha Ramamoorthi

A reflection characteristic analysis device analyzes reflection characteristics of a reconfigurable intelligent surface (RIS: Reconfigurable Intelligent Surface). The reflection characteristic analysis device includes a ray trace calculation unit and an electromagnetic field analysis unit. The ray trace calculation unit calculates an incident angle of an electromagnetic wave incident on the reconfigurable intelligent surface by a ray-tracing method. The electromagnetic field analysis unit acquires the incident angle calculated by the ray trace calculation unit, and calculates, based on an electromagnetic field analysis, the reflection characteristics obtained when the electromagnetic wave enters the reconfigurable intelligent surface at the incident angle.

Reflection characteristic analysis device, reflection characteristic analysis method, and reflection characteristic analysis program

The reflection direction control system includes a plurality of reflection units each including a plurality of reflection elements, a position estimation unit for estimating a position of each of the wireless terminals on the basis of radio waves transmitted to the plurality of reflection parts wireless terminals, a direction estimation unit for estimating an incident direction of the radio waves transmitted by each of the wireless terminals to the reflection units, a phase calculation unit for calculating a phase of the radio waves to be reflected so that the reflection unit reflects the radio waves made incident in the direction estimated by the direction estimation unit in a predetermined direction, and a phase control unit for controlling the phase of the radio waves reflected by each of the plurality of reflection elements on the basis of the phase calculated by the phase calculation unit.

Reflection direction control system, reflection direction control device, reflection direction control method, and reflection direction control program

Communication is performed between a radio base station and a radio terminal via a reflector. The radio base station transmits a measurement signal including a beam ID of a transmission beam for measuring communication quality between the radio base station and the radio terminal. The reflector reflects the measurement signal incident on the reflector in multiple reflection directions to generate multiple reflected measurement signals. Moreover, the reflector modulates the incident measurement signal during reflection to add information about a reflection direction ID being different for each of the multiple reflection directions to each of the multiple reflected measurement signals. The radio terminal demodulates a reflected measurement signal received from the reflector to acquire the reflection direction ID and the beam ID. The radio terminal then evaluates the communication quality for each combination of the beam ID and the reflection direction ID based on reception state of the received reflected measurement signal.

Radio communication method, radio communication system, radio base station, and reflector

A relay apparatus includes a plurality of reflection elements that applies independent phase shifts to an incoming wave, a communication circuitry that receives transmission point information from one or more transmission points, an element allocation circuitry, and a phase control circuitry. The element allocation circuitry determines the number of communication links to be established via the relay apparatus based on the transmission point information, determines the number of reflection elements to be allocated to each of the communication links, and determines a reflection element to be allocated to each of the communication links according to the number of the reflection elements. The phase control circuitry determines the phase weights so that a beam directed to a reception point being a communication destination of each communication link is generated by a reflection wave generated by each reflection element allocated to each of the communication links.

Relay control system, relay apparatus, and relay control method

A wireless transmission device transmits a radio signal with a plurality of beam patterns and outputs transmission beam identifiers corresponding to the beam patterns to an object detection device, a wireless reception device receives the radio signal transmitted by the wireless transmission device with a plurality of beam patterns, measures received signal strength for each of the beam patterns and outputs reception beam identifiers and the received signal strength to the object detection device, and the object detection device detects an object within a detection area on the basis of the transmission beam identifiers, the reception beam identifiers and the received signal strength. This enables device-free object detection by utilizing a beamforming function, so that it is possible to achieve high detection accuracy while preventing increase in cost.

Object detection method, object detection device, and object detection system

A relay system includes: one or more radiation units configured to form a beam in a predetermined direction by radiating radio waves from each of a plurality of elements; a detection unit configured to detect a physical environment on a radio wave propagation path that affects the beam formed by the radiation unit; a direction determination unit configured to determine a direction in which the radiation unit should form the beam based on the physical environment detected by the detection unit; a phase calculation unit configured to calculate a phase of radio wave to be radiated by each of the plurality of elements such that the radiation unit forms a beam in the direction determined by the direction determination unit; and a phase control unit configured to control the phase of the radio wave radiated by each of the plurality of elements based on the phase calculated.

Relay system, relay control device, relay method, and relay control program

A reflection direction control method includes an arrival direction estimation step of estimating an arrival direction of radio waves transmitted by a wireless terminal to one or more reflection units each including a plurality of reflection elements capable of dynamically changing phase characteristics when the radio wave is reflected, a phase control step of controlling a phase of a radio wave reflected by each of the plurality of reflection elements so that the reflection unit reflects, in a predetermined direction, the radio wave transmitted from the estimated arrival direction, and a switching step of switching between an antenna mode in which the reflection unit is caused to receive the radio wave of which the arrival direction is estimated and a reflection mode in which the reflection unit is caused to reflect the radio wave.

Reflection direction control method, reflection direction control system, reflection direction control device, and reflection direction control program

A wireless communication system includes a sensing unit that detects an obstacle currently present between a transmitting station and a receiving station. There is an environment memory that stores information on a detection result of the sensing unit, an environment prediction unit that predicts a variation in a radio wave propagation environment between the transmitting station and the receiving station from the information stored in the environment memory. There is further a simulation calculation unit that simulates an environment in which a communication path between the receiving station and a reflector and a communication path between the transmitting station and the reflector are a line-of-sight environment on the basis of a prediction result of the environment prediction unit and calculates a control parameter of the reflector that achieves the environment. Further, a reflector control unit controls the reflector in accordance with the control parameter calculated by the simulation calculation unit.

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

A predetermined radio base station and subordinate radio terminals detect signals (beacons) regularly transmitted by other radio base stations, transmit information about radio channels and base station identifiers of the detected signals, and position information about the radio terminals to an interference area detection device to aggregate the information and the position information as a base station-base station detection list and a terminal-base station detection list. The interference area detection device compares the lists, determines, for each of positions of the subordinate radio terminals to the predetermined radio base station, whether both of the signal of the predetermined radio base station and a signal of another radio base station, which cannot be detected by the predetermined radio base station, are detected or not, and determines that a position where both of the signals are detected is within an interference area if the predetermined radio base station and the other radio base station detected at the position use the same radio channel.

Interference area detection method for wireless communication system, interference area detection system, interference area detection device, and interference area detection program

Provided is a position estimation method in which a measurement signal and a response signal are transmitted and received between multiple n wireless stations respectively provided with known antennas installed at known positions different from each other and a wireless terminal station provided with a terminal antenna, RTT, which is a round-trip delay time of the transmission and reception, and RSSI, which is a strength of received radio waves of the signals, are measured, and a position of the wireless terminal station is estimated. The method includes: obtaining, as the position of the wireless terminal station, a solution of simultaneous equations of an RTT evaluation function ffor evaluating the estimate value of the position of the wireless terminal station that is estimated based on the RTT measured between the wireless terminal station and the known antenna i (i=1, 2, . . . , n), and an RSSI evaluation function ffor evaluating the estimate value of the position of the wireless terminal station that is estimated based on the RSSI, or a value obtained by searching for an estimate value so that an error evaluation function fobtained by combining the RTT evaluation function and the RSSI evaluation function is minimum.

Position estimation method, position estimation system, position estimation server, and position estimation program

A plurality of access points configured to communicate with a subordinate wireless LAN terminal, an information collecting device configured to collect a frame respectively transmitted and received between the plurality of access points and the wireless LAN terminal, and extract information on communication quality of an access point of the plurality of access points from a header of the frame, and an information collecting server configured to acquire the information on the communication quality of the access point from the information collecting device, analyze the information to determine whether the communication quality is good or bad for each of the plurality of access points, and execute processing of externally displaying or notifying a result that is determined are included.

Wireless LAN communication system, access point communication quality determination method, and information collection server

There are provided a plurality of radio devices detecting an interference source signal transmitted by an interference source and generating pieces of air time information showing whether the interference source signal exists or not for each predetermined time unit; and an aggregation device estimating air time of the interference source by acquiring the pieces of air time information from the plurality of radio devices and aggregating/integrating the acquired pieces of air time information for each predetermined unit time, matching timings.

Wireless communication system, aggregation device, interference source air time acquisition method, and interference source air time acquisition program

A wireless base station and a first wireless terminal include means for collecting first wireless performance information regarding wireless communication in both a downstream direction and an upstream direction and transmitting the first wireless performance information to a wireless performance measurement device. The wireless base station and a second wireless terminal include means for collecting second wireless performance information regarding wireless communication in both the downstream direction and the upstream direction and transmitting the second wireless performance information to the wireless performance measurement device. The wireless performance measurement device includes means for obtaining a first comparison result by comparing the first wireless performance information regarding the upstream direction and the downstream direction, obtaining a second comparison result by comparing the second wireless performance information regarding the upstream direction and the downstream direction, and determining the location where an abnormality occurred in accordance with a result of a comparison of the first comparison result and the second comparison result. The location is determined from among the wireless base station, the first wireless terminal, the second wireless terminal, and a wireless propagation environment between the wireless base station and the first wireless terminal and between the wireless base station and the second wireless terminal.

Radio performance measurement system, radio performance measurement method, radio performance measurement device, and radio performance measurement program

There are provided an information collecting device configured to collect a frame A transmitted and received between a wireless LAN base station that is an evaluation target and a wireless LAN terminal subordinate to the wireless LAN base station that is the evaluation target and a frame B transmitted and received between a wireless LAN base station that is a non-evaluation target and a wireless LAN terminal subordinate to the wireless LAN base station that is the non-evaluation target, and extract radio information on communication quality of each of the wireless LAN base stations from a header of a corresponding one of the frames A and B, and a wireless LAN communication quality estimation device configured to acquire, from the wireless LAN base station that is the evaluation target, information on the number of currently connected wireless LAN terminals, acquire, from the information collecting device, the radio information on the communication quality of each of the wireless LAN base stations, and analyze the information to estimate whether the communication quality of the wireless LAN base station that is the evaluation target is good or bad.

Wireless LAN communication quality estimation method, wireless LAN communication quality estimation system, information collection device, and wireless LAN communication quality estimation device

In a wireless information collecting method executed by at least one user terminal device that measures wireless information used in a site survey and a server device that stores the wireless information and performs the site survey, the user terminal device performs a step of periodically measuring a current position and transmitting positioning information indicating the current position to the server device, and a step of measuring the wireless information in accordance with a wireless information measurement number instructed by the server device and transmitting wireless information including a position and time to the server device. The server device performs a step of associating a position of the user terminal device and time with the wireless information and creating and updating a condition map indicating a wireless information measurement number at a position and time at which a site survey is performed, and a step of collating the current position of the user terminal and the time with the condition map and transmitting an instruction for the wireless information measurement number based on the current position of the user terminal device and the time to the user terminal device.

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Musashino, Japan

Tomoaki Ogawa