Nippon Telegraph and Telephone Corporation

Yutaka Imaizumi

Naoki Kita

Kota Ito

Yushi Shirato

Kazuto Goto

Hideyuki Tsuboi

Munehiro Matsui

Atsushi Ota

Daisuke Goto

Fumihiro Yamashita

Koichi Harada

Hiroki Shibayama

Masaki Shima

Izumi Urata

Hiroyuki Nakamura

Chunhsiang Huang

Satoshi Kurosaki

A band sharing communication system in which there are an N-ary system and an N+1-ary system in descending order of priority of communication, the systems share frequency bands and allocation of a requested band of a terminal station of each system is performed, includes: occupied band setting means for setting an N-ary occupied band and an N+1-ary occupied band adjacent to the N-ary occupied band; band allocation means for allocating a vacant band of the N-ary occupied band with respect to a requested band of an N-ary terminal station and allocating a vacant band of the N+1-ary occupied band with respect to a requested band of an N+1-ary terminal station; and band transferring means for, when there is no vacant band in the N-ary occupied band with respect to the requested band of the N-ary terminal station, if a vacant band equivalent to the requested band is present in the N+1-ary occupied band such that the vacant band is adjacent to the N-ary occupied band, transferring the vacant band from the N+1-ary occupied band to the N-ary occupied band and allocating the vacant band to the N-ary terminal station, and if communication is being performed in a band in the N+1-ary occupied band which is adjacent to the N-ary occupied band and equivalent to the requested band, transferring a vacant band created by making a suspension request to the N+1-ary terminal station performing the communication from the N+1-ary occupied band to the N-ary occupied band and allocating the vacant band to the N-ary terminal station.

Band sharing communication system, line control method, line control device, and line control program

In a band sharing communication system in which there are a primary system and a secondary system in descending order of priority of communication, the systems share frequency bands, and a base station or a line control device performs allocation of a requested band of a terminal station of each system, the base station or the line control device includes: occupied band setting means for setting a primary occupied band and a secondary occupied band adjacent to the primary occupied band; band allocation means for allocating a vacant band of the primary occupied band with respect to a requested band of a primary terminal station and allocating a vacant band of the secondary occupied band with respect to a requested band of a secondary terminal station; and band transferring means for, when there is no vacant band in the primary occupied band with respect to the requested band of the primary terminal station, if a vacant band equivalent to the requested band is present in the secondary occupied band such that the vacant band is adjacent to the primary occupied band, transferring the vacant band from the secondary occupied band to the primary occupied band and allocating the vacant band to the primary terminal station, and if communication is being performed in a band in the secondary occupied band which is adjacent to the primary occupied band and equivalent to the requested band, transferring a vacant band created by making a suspension request to the secondary terminal station performing the communication from the secondary occupied band to the primary occupied band and allocating the vacant band to the primary terminal station.

A projection unit () of an interference power estimation device () projects an orbit of a satellite onto a map representing a ground surface. A range acquisition unit () determines a plurality of ranges on the map so that the projected orbit is included in the ranges. An altitude calculation unit () calculates an altitude of the orbit of the satellite in each of the ranges. A range interference calculation unit () calculates, for each of the ranges, an interference power between the satellite at a position determined by a latitude and a longitude of the range and the altitude calculated for the range and a radio station installed on the ground surface. An estimation result calculation unit () selects, as an estimation result, a maximum value among the interference powers calculated for each of the ranges.

Interference power estimation method, interference power estimation apparatus and program

A receiving station performs first signal detection processing on a received radio signal, performs a retransmission request to a transmitting station in a case in which a code error is detected in a detected radio packet for user data, and enqueues the radio packet in a reception buffer in a case in which no code error is detected. In parallel with the first signal detection processing, the receiving station performs second signal detection processing on the received signal with a longer processing delay than that of the first signal detection processing, and in a case in which no code error is detected in the detected radio packet for user data, the receiving station enqueues the radio packet in the reception buffer. The receiving station outputs, at a predetermined timing, the radio packet for user data with no code error detected, the radio packet being enqueued in the reception buffer.

Retransmission control method

A wireless communication system which includes first and second wireless station apparatuses having a plurality of antenna elements and performs directivity forming. For Tand Tsuch that T=N&#xd7;Tand T=N&#xd7;Twith a predetermined period T, the wireless communication system performs the steps of sequentially switching Ntypes of directional beams at intervals of period Tand transmitting signals while performing switching with an identical directional beam switching pattern maintained over period T, sequentially switching Ntypes of directional beams at intervals of period Tand receiving signals over the period Tor more while performing switching with an identical directional beam switching pattern maintained over the period T, searching for a directional beam having a highest reception level among those acquired over a predetermined period, and setting the searched directional beam as a directional beam to be used.

Apparatus search for optimal directional beams

To provide an interference evaluation apparatus including a station information storage unit configured to store interfering station information indicating station information related to an interfering station causing radio interference in radio communication and interfered station information indicating station information related to an interfered station receiving the interference, and a determination unit configured to perform an interference calculation for calculating an interference power, based on the interfering station information and the interfered station information stored in the station information storage unit, and determine whether the interfering station and the interfered station are usable together, based on the calculated interference power and an acceptable interference power in the interfered station.

Interference evaluation device, evaluation method and evaluation program

The interference power estimation apparatuscalculates an inter-station vector from an interfering station over a sphere to an interfered station installed in the sphere based on a position of each station. In a case where a line segment connecting the position of the interfered station and the position of the interfering station does not intersect with the sphere, an angle between an antenna direction vector representing a direction of an antenna from the position of the interfered station and the inter-station vector is derived, and a sum of an antenna directivity attenuation amount obtained based on the angle and propagation losses calculated based on a distance between the interfered station and the interfering station is calculated. The interference power estimation apparatuscalculates the sum for each of a plurality of possible positions of the interfering station, but does not calculate the sum in a case where the line segment connecting the position of the interfered station and the position of the interfering station intersects with the sphere. The interference power estimation apparatuscalculates interference power from the interfering station, based on a minimum value of the calculated sum.

Growing community of inventors

Musashino, Japan

Yutaka Imaizumi