Nippon Telegraph and Telephone Corporation

Munehiro Matsui

Masato Mizoguchi

Yasushi Takatori

Riichi Kudo

Takeo Ichikawa

Koichi Ishihara

Hirantha Abeysekera

Yutaka Miyamoto

Etsushi Yamazaki

Takayuki Kobayashi

Akihide Sano

Eiji Yoshida

Tadao Nakagawa

Yusuke Asai

Shoko Shinohara

Tomoki Murakami

Akiyoshi Inoki

Takahiro Asai

Hideyuki Nosaka

Daisuke Goto

Kenichi Kawamura

Akira Yamada

Shogo Yamanaka

Akira Kishida

Yoshifumi Morihiro

Fumihiro Yamashita

Yutaka Imaizumi

Koichi Harada

Hiroki Shibayama

Masaki Shima

Izumi Urata

Yasuhiko Inoue

Tomoyuki Yamada

Keisuke Wakao

Eiichi Yamada

Daisuke Koizumi

Hirantha Sithira Abeysekera

Provided is a wireless communication system in which, based on a random access scheme, a transmission opportunity (TXOP) acquired by a wireless access point is granted to a wireless station when performing uplink data transmission from the wireless station to the wireless access point and the TXOP acquired by the wireless station is granted to the wireless access point when performing downlink data transmission from the wireless access point to the wireless station, the system includes a scheduling unit for TXOP granting determining one or more wireless stations having a quality of an uplink data transmission lower than a prescribed value as TXOP responders to which the wireless access point grants the TXOP, and determining one or more wireless stations having a quality of a downlink data transmission lower than the prescribed value as TXOP holders which grant the TXOP to the wireless access point.

Wireless communication system and wireless communication method

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.

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

Provided is a wireless communication system which performs downlink data transmission based on a transmission opportunity acquired by a wireless access point (hereinafter referred to as TXOP access) or a transmission opportunity acquired by a wireless station and granted to the wireless access point (hereinafter referred to as RXOP access), when performing the downlink data transmission from the wireless access point to the wireless station based on a random access scheme, in which the wireless access point includes a control unit performing, on a transmission buffer which sequentially stores data frames to be transmitted for each of wireless stations, processing which lowers an order of priority of the data frames which are to be destined for the wireless station A by the TXOP access at the transmission buffer according to a transmission status of the data frames destined for a wireless station A by the RXOP access.

Provided is a wireless environment evaluation method including a stepacquiring a transmission and reception history of wireless signals transmitted and received between the plurality of wireless stations and acquiring or estimating a number of wireless stations in transmission standby, based on the transmission and reception history; a stepcalculating a normal reception rate S in a congesting situation in reception according to the number of wireless stations in transmission standby; a stepacquiring a normal reception rate S' of the wireless signals per a fixed channel use time from the transmission and reception history in the prescribed wireless station; and a stepdetermining a degree of the exposed situation in reception according to a ratio of the normal reception rate S&#x2032; to the normal reception rate S.

Wireless environment evaluation method and wireless communicaton system

A wireless environment information collection system in which the wireless environment information management unit includes a unit which generates and outputs a channel measurement frame which determines the wireless stations performing stopping of communication over the first frequency channel for a fixed time, starting of measuring channel utilization of the first frequency channel, or both the stopping and the starting among the managed wireless stations, and the managed wireless stations include a unit which performs, at a time designated by the channel measurement frame from the wireless environment information management unit, the stopping of the communication over the first frequency channel, the measuring of the channel utilization of the first frequency channel, or both the stopping and the measuring, and which outputs the obtained wireless environment information to the wireless environment information management unit through the wired network or the wireless network.

Wireless environment information collection system and method

A wireless communication apparatus is provided that is capable of performing setting of a wireless LAN access point so that frequency utilization efficiency of an entire wireless communication system that includes wireless LAN access points of different manufacturers and different model numbers is improved. A wireless communication system which performs setting necessary for a wireless LAN access point constituting a wireless communication network to operate includes: an information collection unit which collects setting information set in the wireless LAN access point and wireless environment information in the wireless LAN access point, a parameter calculation unit which obtains a parameter to be set for the wireless LAN access point, which is a collection source, based on the collected setting information and the collected wireless environment information, and a parameter setting unit which transmits the obtained parameter to the wireless LAN access point, which is a collection source, over a network and performs setting of the parameter.

Wireless communication apparatus, wireless communication system, and wireless communication method

To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus. Moreover, the optical signal receiving apparatus detects a clock offset between the optical signal receiving apparatus and the optical signal transmitting apparatus from an interval between the estimated frequency positions of the specific frequency band signals. Furthermore, the optical signal receiving apparatus estimates temporal positions of the detected specific frequency band signals and detects a chromatic dispersion amount from a difference between the temporal positions of the specific frequency band signals corresponding to different frequencies.

Signal generating circuit, optical signal transmitting apparatus, signal receiving circuit, method for establishing optical signal synchronization, and optical signal synchronization system

Provided are a wireless communication method, a base station, a wireless communication system and a communication apparatus whereby an interference power is calculated from an estimated propagation channel estimation result and the transmission power is controlled based on the interference power or the interference is suppressed by controlling the directivity, thereby increasing the transmission capacity. A propagation channel estimation circuit performs propagation channel estimation from a response signal transmitted from a terminal station and estimates a propagation channel estimation result. An interference power calculation circuit measures each interference power from a signal of each sub-carrier received by each of wireless units, and calculates an interference power for each sub-carrier from the propagation channel estimation result estimated by the propagation channel estimation circuit. When the calculated interference power is equal to or more than a predetermined threshold, an interference suppression signal generation circuit changes the transmission power and generates an interference suppression signal.

Wireless communication method, base station, wireless communication system, and communication apparatus

Growing community of inventors

Yokosuka, Japan

Munehiro Matsui