Nippon Telegraph and Telephone Corporation

Takeshi Onizawa

Naoki Kita

Yushi Shirato

Masato Mizoguchi

Kazuto Goto

Tomoaki Kumagai

Hideyuki Tsuboi

Hideki Toshinaga

Masahiro Morikura

Kota Ito

Shuki Wai

Tetsu Sakata

On two-dimensional map data indicating buildings serving as candidates for installing terminal station devices, locations of base station installation structures serving as candidates for installing base station devices are set as base station candidate locations, and for each of the base station candidate locations, buildings that have other buildings between themselves and the base station candidate location are selected as visibility detection subject buildings. The heights of the buildings are set at an identical length, a higher position than the buildings is set as an installation altitude of the base station devices, and for each selected visibility detection subject building, a visibility range of the visibility detection subject building from the installation altitude of the base station device in the base station candidate location is detected. Three-dimensional point cloud data acquired by photographing a region including the base station installation structures and the buildings are narrowed down on the basis of the detected visibility ranges, and using the narrowed-down point cloud data, the visibility of the buildings from the base station candidate locations is determined.

Station placement designing method and station placement designing apparatus

Using an array antenna in which a spacing between adjacent antenna elements is constant, each of combinations of two antenna elements in positions symmetrical relative to a center of an array is connected by wire connections in two paths, and a path length between the antenna elements in the combination of two antenna elements is the same in all of the combinations: a phase adjustment amount is calculated for each wire connection aside from a reference wire connection on the basis of an arrival direction of a wireless signal received by one antenna element in the combination of two antenna elements and a re-radiation direction of a wireless signal transmitted as a re-radiated wave by the other antenna element corresponding to the one antenna element, taking into account a phase difference between a signal transmitted by the wire connections connected to the one antenna element and a signal transmitted by the reference wire connection; and phase rotation is applied to the signal transmitted by the wire connections aside from the reference wire connection in accordance with the calculated phase adjustment amount.

Relay apparatus and relay method

In two-dimensional map information showing communication equipment installation structures on which communication equipment is installed, roads, and buildings, a narrow region between the buildings is detected based on a distance of an interval of the buildings adjacent to each other and a predetermined length and a connection line connecting the buildings is imparted to an opened portion of the detected narrow region, a line-of-sight detection line is extended with any one of the communication equipment installation structures set as a start point and the line-of-sight detection line is rotated around the start point, intersections of the line-of-sight detection line and a contour line of the building or the connection line is detected and the intersection at a shortest distance from the start point among the detected intersections is detected as a line-of-sight intersection, and, when the line-of-sight intersection and another line-of-sight intersection belong to the same building, a line-of-sight range line along the contour line of the building is imparted to between the two line-of-sight intersections.

Perspective detection method, perspective detection apparatus and perspective detection program

A preamble for synchronization, or a reference timing for operation of an OFDM packet communication receiver system is detected finely even under environment of large waveform distortion due to thermal noise and/or multi-path propagation, and/or large carrier frequency offset between a transmit side and a receiver side. A correlator ( ) detects a pattern of a short preamble (t -t ) in a preamble for synchronization. An output of the correlator ( ) is applied to a complex filter ( ) which separates a short preamble having a predetermined repetition period from uniformly distributed noise. A scalar filter ( ) integrates some period of short preambles which have distributed-delay by multi-path propagation as if a single short preamble with no delay were received for determining a reference timing. When a correlator output exceeds a predetermined threshold level a plurality of times for every repetition periods (T) of a short preamble, and an output of the correlator after time (T) from the last short preamble is decreased a predetermined ratio as compared with that of the last short preamble, it is determined that a preamble for synchronization is detected. Carrier frequency offset compensation is carried out either for each short preamble during reception of a short preamble, or based upon the last received short preamble during reception of an OFDM symbol after the last short preamble. As a preamble for synchronization is detected accurately, a guard interval of each OFDM symbol is removed accurately, or an FFT window is defined accurately, so that a demodulation is possible in spite of noise and/or interference.

OFDM packet communication receiver system

A coherent detection system for multicarrier modulation system capable of accurate channel estimation even in severe environment with high thermal noise and deep multipath fading, has been found with simple structure and small circuit size. The present coherent detection system comprises a channel estimation circuit ( ) for estimating a channel attenuation of a preamble part of each subcarriers, an adaptive filter ( ) for smoothing estimated channel attenuation among subcarriers, a divider ( ) for coherent detection of a data part by dividing a receive vector by smoothed estimated channel attenuation for each subcarriers, and a characteristic extraction circuit ( ) for extracting characteristic value of each subcarriers. The adaptive filter ( ) is controlled depending upon characteristic value of each subcarriers measured by the characteristic extraction circuit ( ). A characteristic value may be amplitude, phase rotation, vector difference, modulation system, of each subcarriers, and/or combination of those values.

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Kanagawa, Japan

Takeshi Onizawa