Fujitsu Corporation

The University of Tokyo

Fujitsu Network Communications, Inc.

Yasuhiko Aoki

Shoichiro Oda

Kyosuke Sone

Goji Nakagawa

Takeshi Hoshida

Setsuo Yoshida

Susumu Kinoshita

Yutaka Kai

Hisao Nakashima

Toshiki Tanaka

Hideyuki Miyata

Osamu Takeuchi

Guoxiu Huang

Hiroki Oi

Toru Katagiri

Takahito Tanimura

Yutaka Takita

Satoru Okano

Cechan Tian

Masahiro Shioda

Masatake Miyabe

Yoshiaki Nakano

Jeng-Yuan Yang

Eric Gouardes

Zhenning Tao

Hiroyuki Seki

Takao Naito

Kentaro Nakamura

Olga I Vassilieva

Koji Takeguchi

Tomohiro Yamauchi

Yohei Koganei

Tomohiro Ueno

Masaji Noguchi

Shigeru Ishii

Toshihisa Kyouno

Yoichi Akasaka

Hayato Furukawa

Rui Chu Chang

Kyousuke Sone

Kouichiro Amemiya

Ryan Pettijohn

A network controller includes: a first acquisition unit configured to acquire, based on a signal quality amount of each of wavelength paths set in a network of an optical wavelength-multiplexed transmission system, a signal quality amount of each of spans in each of the wavelength paths; an arithmetic unit configured to calculate a signal quality amount of each of spans in a wavelength path of an estimation target, based on the signal quality amount acquired by the first acquisition unit; and an estimation unit configured to estimate a signal quality amount of the wavelength path of the estimation target, based on the signal quality amount calculated by the arithmetic unit.

Network controller and signal quality estimating method

An optical transmission characteristic measurement method includes starting transmission of an optical signal from a transmitting node to a receiving node; receiving a bit error rate value measured by the receiving node and relates to the optical signal; determining whether the bit error rate value is higher than a given threshold; adjusting input power of the optical signal to lower until it is determined that the bit error rate value is higher than the given threshold when it is determined that the bit error rate value is not higher than the given threshold; estimating an optical signal to noise ratio from the bit error rate value when it is determined that the bit error rate value is higher than the given threshold; and calculating an optical signal to noise ratio based on the estimated optical signal to noise ratio and an amount of lowering of the input power.

Optical transmission characteristic measurement device and method

A transmitter generates a frequency-modulated CW light so as to transmit it to a path. A receiver receives the CW light that has passed through passband filters included in the path. The receiver includes a processor. The processor measures an optical power of the received CW light every time a center frequency of the CW light is changed and transmitted by the transmitter. The processor calculates transmission characteristics of the CW light that has passed through the passband filters, on the basis of an average value of the optical power that corresponds to a center frequency of the CW light and on the basis of an amplitude component that indicates an amount of change in the optical power, the average value and the amplitude component being obtained as a result of the measurement.

Transmission device and method for measuring optical transmission characteristics

An optical communication system includes an optical transmitter, a plurality of optical receivers, and a splitter that splits light transmitted by the optical transmitter to the plurality of optical receivers. The optical transmitter includes a variable-wavelength light source capable of transmitting light of a first wavelength and light of a third wavelength between the first wavelength and a second wavelength. A first optical receiver of the plurality of optical receivers includes a first optical filter having a first transmission band including the first and third wavelengths, and a first receiving unit that receives light having passed through the first optical filter. A second optical receiver of the plurality of optical receivers includes a second optical filter having a second transmission band including the second and third wavelengths, and a second receiving unit that receives light having passed through the second optical filter.

Optical communication system, transmission station, and method of optical communication

A processor of an optical transport apparatus is configured to transport an optical multiplexed signal between the optical transport apparatus and a counterpart apparatus by using a plurality of communication units; transmit an arbitrary optical wavelength from the optical multiplexed signal passing through ports by using a wavelength selective switch that has the ports respectively connected to the communication units; control a radio unit in the counterpart apparatus so as to change a frequency of the radio signal in the specified optical wavelength; and change a transmission band of the port through which the optical wavelength passes, according to a change of the frequency of the radio signal. The processor is configured to control an optical transmission unit of the counterpart apparatus so as to change a center wavelength of an optical wavelength passing through the port to a center wavelength of the changed transmission band of the port.

Optical transport apparatus and optical-wavelength defragmenting method

There is provided an apparatus configured to estimate optical transmission performance in a transmission path of an optical signal, the apparatus including a memory, and a processor coupled to the memory and the processor configured to acquire a first index related to a first transmission performance of an optical signal transmitted through a span group between a first node and an n-th node and a second index related to a second transmission performance of an optical signal transmitted through a span or a span group between the first node and an m-th node, wherein n is an integer of 3 or more, and m is the integer satisfying m&#x3c;n, and estimate a third index related to a third transmission performance of an optical signal to be transmitted through a span between the m-th node and the n-th node, based on the first index and the second index.

Apparatus and method for estimating optical transmission performance

An optical signal-to-noise ratio monitor includes: a measuring unit that measures an optical signal-to-noise ratio of a polarization multiplexed optical signal, a polarization state of the polarization multiplexed optical signal changing with respect to time; a selector that selects, from a plurality of optical signal-to-noise ratios measured by the measuring unit at a plurality of measurement points within a designated measurement period, an optical signal-to-noise ratio that is higher than an average of the plurality of optical signal-to-noise ratios; and an output unit that outputs the optical signal-to-noise ratio selected by the selector.

Optical signal-to-noise ratio monitor and method for measuring optical signal to-noise ratio

An optical signal quality monitoring apparatus includes: a holding unit configured to hold a relational expression representing a relationship among an optical signal intensity, a noise intensity, and an optical signal-to-noise ratio and a plurality of calibration coefficients used in the relational expression; a measurement unit configured to measure an optical power of input light and a noise power in the input light; an arithmetic unit configured to calculate a plurality of optical signal-to-noise ratios, based on the optical power and the noise power measured by the measurement unit, by using the relational expression and the plurality of calibration coefficients; and a determination unit configured to select one optical signal-to-noise ratio from the plurality of optical signal-to-noise ratios, based on a magnitude relationship of the plurality of optical signal-to-noise ratios calculated by the arithmetic unit.

Optical signal quality monitoring apparatus, optical signal quality monitoring method and optical repeater

A transmission characteristics monitoring device monitors transmission characteristics of an optical transmission path between nodes. The device detects an average power of the frequency modulated optical signal and a slope of the transmission characteristics; generates a slope function that represents a slope of the transmission characteristics between first and second frequencies; generates a corrected power value by adding an integral of the slope function to a first power measurement value detected at the first frequency; calculates the transmission characteristics at the second frequency based on a second power measurement value detected at the second frequency when the difference between the second power measurement value and the corrected power value is smaller than a specified threshold; and calculates the transmission characteristics at the second frequency based on the corrected power value when the difference is greater than the specified threshold.

Device and method for monitoring transmission characteristics

An optical line termination includes a detection circuit configured to detect a sleep request from a control apparatus to base stations; a determination circuit configured to determine, when the detection circuit detects the sleep request, whether processing of turning the base stations of requestees by the sleep request into a sleep state in accordance with the sleep request is approvable or not, based on a shortage bandwidth within a passive optical network in a different one of the base stations having a predetermined relationship with the requested base station; and a control circuit configured to discard the sleep request when the determination circuit determines that the processing is not approvable, or transfer the sleep request to the base station of the different requestee when the determination circuit determines that the processing is approval.

Optical line termination, communication system, and communication control method

An optical receiver includes: a tunable filter configured to partially transmit a wavelength-multiplexed optical-signal including a first optical-signal having a first wavelength, a second optical-signal having a second wavelength, and a third optical-signal having a third wavelength, with a frequency-modulated signal superimposed on each of the first to third optical-signals; a photo detector configured to detect an optical-power of the wavelength-multiplexed optical-signal transmitted through the tunable filter; and a superimposed signal detector configured to detect the frequency-modulated signal superimposed on the first optical-signal, based on an amplitude-modulated signal according to a variation in the optical-power on a first filter setting where both of the first optical-signal and the second optical-signal transmit through the tunable filter, and an amplitude-modulated signal according to a variation in the optical-power on a second filter setting where both of the first optical-signal and the third optical-signal transmit through the tunable filter.

Optical receiver and superimposed signal detecting method

An optical communication system includes: a first network-side device and a second network-side device each coupled to a communication network; and a first terminal-side device and a second terminal-side device configured to communicate with the first network-side device and the second network-side device by being coupled to the first network-side device and the second network-side device via a first communication cable and a second communication cable, respectively, wherein the first network-side device is coupled to the first terminal-side device via the communication network, the second network-side device, and a third communication cable for coupling the second network-side device and the first terminal-side device so as to communicate between the first network-side device and the first terminal-side device.

Optical communication system and optical communication method

A communication device that receives received signal light from another communication device, the communication device includes: a receiver configured to receive signal light output from an optical filter that outputs signal light of a given wavelength included the received signal light; and a transmitter configured to transmit, to the another communication device, a control signal for controlling a wavelength of laser light for use in generation of the signal light of the given wavelength, wherein the receiver is configured to detect power of the signal light output from the optical filter; and the transmitter is configured to set, when the signal light is not successfully received in the receiver, the control signal so as to cause the another communication device to control the wavelength of the laser light, based on the power.

Communication device and wavelength adjustment method

A transmitting device coupled to a first route and a second route as communication paths on a first ring network and coupled to a third route as a communication path on a second ring network, the transmitting device includes: a first branching unit configured to branch and output signal light input from the first route to a first terminating unit and a second output unit that outputs signal light to the second route; a second branching unit configured to branch and output signal light input from the second route to a second terminating unit, a first output unit that outputs signal light to the first route, and a third output unit that outputs signal light to the third route; and a third branching unit configured to branch and output signal light input from the third route to a third terminating unit that terminates signal light and the second output unit.

Transmitting device and transmission control method

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Yokohama, Japan

Yasuhiko Aoki