Fujitsu Corporation

Tomoo Takahara

Masato Nishihara

Toshiki Tanaka

Yutaka Kai

Takeshi Hoshida

Hiroki Ooi

Ryou Okabe

George Ishikawa

Kentaro Nakamura

Yuichi Akiyama

Naoki Kuwata

Takafumi Terahara

Masahiro Yuki

Junichi Kumasako

Takashi Iwabuchi

Hisao Nakashima

Toru Katagiri

Shoichiro Oda

Jens Rasmussen

Yoshinori Nishizawa

Shigeki Watanabe

Takahito Tanimura

Akira Miura

Tomoyuki Kato

Jens C Rasmussen

An optical transmission device includes: an optical transmitter that transmits, at a time of system activation, a control signal to another optical transmission device by using a plurality of subcarriers; and a controller that allocates a link communication channel (LCC) to a subcarrier, among the plurality of subcarriers, for which bare minimum transmission characteristic is obtained, based on a response to the control signal from the other optical transmission device.

Optical transmission device, optical transmission system, and allocation method

A transmission device is implemented in a first node in an optical transmission system in which a frame is transmitted from the first node to a second node via an optical interface. The transmission device includes a decision unit that decides whether a type of a first error correction code used in the first node is the same as a type of a second error correction code used in the second node. When a type of the first error correction code is the same as a type of the second error correction code, the transmission device transmits the frame to which an error correction code used in the first node is added to the second node without terminating the error correction code.

Device and method for transmitting frame in optical transmission system

A transmission device connects a plurality of transmission device by a ring network. The transmission device includes a generating unit, a transmission unit, a determination unit, and a setting unit. The generating unit generates a test signal. The transmission unit transmits the generated test signal to a first transmission device provided immediately downstream in the ring network. The determination unit determines whether a transmission characteristic of the own device on the basis of the test signal measured by the first transmission device is acquired from a second transmission device provided immediately upstream by rounding the ring network. The setting unit sets, on the basis of the acquired transmission characteristic when the transmission characteristic of the own device is acquired, a control level related to the transmission performed by the transmission unit.

Transmission device and setting method

A receiving device includes an optical filter, an acquisition unit, a first determination unit, and a filter setting unit. The optical filter transmits an optical DMT signal received from a sending device. The acquisition unit acquires the transmission characteristics of the optical DMT signal received from the sending device. The first determination unit determines a filter frequency of the optical filter that removes a dip from the optical DMT signal on the basis of the acquired transmission characteristics. The filter setting unit sets the determined filter frequency in the optical filter.

Receiving device and sending device

A method for estimating characteristics of an optical receiver includes: a generating process, a monitoring process, a suppressing process, a guiding process and an estimating process. The generating process generates a modulated optical signal based on an oscillation signal. The monitoring process monitors an optical spectrum of the modulated optical signal or a spectrum of an electric signal obtained by performing optical-to-electrical conversion on the modulated optical signal. The suppressing process suppresses a modulation component of an upper sideband or a lower sideband of the modulated optical signal based on the optical spectrum of the modulated optical signal or the spectrum of the electric signal. The guiding process guides the modulated optical signal in which the modulation component is suppressed to the optical receiver. The estimating process estimates the characteristics of the optical receiver based on an output signal of the optical receiver.

Estimation method for optical receiver and light source device

There is provided a transmission apparatus includes: a first modulator configured to modulate a first electrical signal to a second electrical signal that is a multicarrier signal including a plurality of subcarriers to which transmission capacities are allocated, respectively; a light source configured to generate light having a predetermined wavelength; a second modulator configured to modulate the light generated by the light source to an optical signal, based on the second electrical signal modulated by the first modulator; and a processor configured to: measure a first frequency distribution of intensity of the second electrical signal modulated by the first modulator, measure a second frequency distribution of intensity of the optical signal modulated by the second modulator, compare the first frequency distribution and the second frequency distribution, and control modulation characteristics of the second modulator according to a result of comparing the first frequency distribution and the second frequency distribution.

Transmission apparatus and transmission method

An optical transmitter transmits to an optical receiver a multi-carrier modulated signal light by driving a light source with a modulated signal modulated with a multi-carrier modulation scheme. The optical receiver monitors reception characteristic of any of subcarrier signals included in the modulated signal and transmits a monitor result to the optical transmitter. The optical transmitter controls drive conditions of the light source based on the monitor result received from the optical receiver.

Multi-carrier optical transmission system, optical transmitter, and optical receiver

An optical signal receiving device includes a receiver configured to receive an optical signal on which modulation has been performed by an optical signal transmission device, a convertor configured to convert the optical signal received by the receiver to a digital signal by sampling an intensity of the optical signal, and a processor coupled to the converter and configured to determine, based on a frequency distribution of the intensity of the optical signal indicated by the digital signal converted by the converter, a modulation scheme of the modulation performed by the optical signal transmission device.

Optical signal receiving device and method of receiving an optical signal

An optical reception apparatus may include a receiver, a monitor, and a controller. The optical reception apparatus receives multi-carrier modulated signal light modulated by a multi-carrier modulation scheme. The multi-carrier modulation scheme is available to allocate different transmission conditions for each of a plurality of subcarriers in accordance with transmission characteristics of the subcarriers. The receiver may receive from an optical transmission line a training signal light allocated with the same transmission conditions for each of the subcarriers. The monitor may monitor the transmission characteristics of the training signal light to detect a frequency at which a dip of the transmission characteristics occurs. The controller may control, based on the frequency detected by the monitor, a dispersion compensation for the multi-carrier modulated signal light having received a dispersion from the optical transmission line.

Optical reception apparatus

An optical transmitter includes an optical modulator to modulate light having a predetermined wavelength into an optical signal based on a data signal, a memory, and a processor coupled to the memory and the processor configured to modulate an input signal into a multi-carrier signal so as to generate the data signal, the multi-carrier signal including a plurality of subcarriers each to which a transmission capacity is allocated, acquire a first frequency distribution of an intensity of the multi-carrier signal, acquire a second frequency distribution of an intensity of the optical signal, control the modulating of the input signal into the multi-carrier signal to change a number of subcarriers of the multi-carrier signal, and control the optical modulator to adjust a modulation characteristic of the optical modulator so that a divergence between the first frequency distribution and the second frequency distribution is equal to or less than a predetermined value.

Optical transmitter, optical communication system, and optical transmission/reception control method

An apparatus includes a receiver configured to receive a signal that has traveled an optical transmission line without returning output from an optical transmitting device and synchronize with the optical transmitting device in order to demodulate the signal; a dispersion compensator configured to compensate for wavelength dispersion caused by transmission of the signal; an acquisition circuit configured to acquire a transmitting timing at which the signal has been transmitted from the optical transmitting device; a calculation circuit configured to calculate a transmission time period from the optical transmitting device to the receiver from the transmitting timing and a receiving timing at which the signal has been received with the receiver; and an amount setting circuit configured to adjust a dispersion compensation amount of the dispersion compensator in accordance with the transmission time period.

Optical receiving device and method for controlling dispersion compensation amount

A transmission apparatus including: a waveform shaper that performs spectrum correction on an optical signal converted from an electrical signal encoded by OFDM (Orthogonal Frequency Division Multiplexing); a converter that converts the optical signal on which the waveform shaper has performed the spectrum correction, into the electrical signal; and a nonlinear compensator that compensates for a nonlinear distortion with respect to the electrical signal converted by the converter.

Transmission apparatus and transmission system

An optical transmitter includes a discrete multi-tone (DMT) modulation unit that modulates a carrier signal having a specific frequency with an information signal and a carrier signal having a frequency different from the specific frequency with a monitor signal, to generate a DMT modulation signal that multiplexes the information signal and the monitor signal. The optical transmitter includes a laser diode (LD) unit that optically converts the DMT modulation signal to a corresponding optical DMT modulation signal, a frequency extraction unit that extracts a harmonic distortion component of the monitor signal from the optical DMT modulation signal, and a frequency analysis unit. The optical transmitter includes a bias control unit that controls a bias supply unit that adjusts a bias value to be supplied to the LD unit such that the extracted harmonic distortion component of the monitor signal is reduced.

Optical signal processing apparatus, optical signal processing method, and recording medium

There is proved an optical transmission system including: a transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal; a filter capable of changing a wavelength of the optical signal input from the transmitter; a monitor configured to monitor a power of the optical signal passed through the filter; and at least one processor configured to: set a center wavelength of the filter, shift the center wavelength, detect a change in the power monitored by the monitor, identify a carrier component of the optical signal based on the change in the power, and control a relative relationship between a transmission characteristic of the filter and a wavelength of the carrier component so that the carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the filter.

Optical transmission system, controller for wavelength tunable filter, and control method of wavelength tunable filter

A bit allocation method is used in an optical transmission system that transmits multicarrier signals of different wavelengths in wavelength division multiplexing. Frequency characteristics of subcarriers included in the multicarrier signals are different between the respective multicarrier signals. The method includes: measuring transmission characteristics of the subcarriers included in corresponding multicarrier signals at different subcarrier frequencies; and determining a number of bits to be allocated to each of the subcarriers included in each of the multicarrier signals based on the transmission characteristics measured at the different subcarrier frequencies.

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Kawasaki, Japan

Tomoo Takahara