Fujitsu Corporation

Yuji Kamura

Masayuki Tanaka

Ichiro Nakajima

Taku Saito

Satoshi Nemoto

Masaki Hiromori

Yoshinori Tochiki

Masato Hashizume

Shingo Hironaka

Megumi Shibata

Toshiaki Asai

Yoshinari Oshio

Masaki Kubo

Shigeo Handa

Seiji Matsuzaki

Shuji Sakakura

A transmission system includes: a first transmission device that receives a first signal from the work path; a second transmission device, coupled to a protection path in a redundant configuration with respect to the work path, that receives a second signal from the protection path; and a first communication device coupled to the first and second transmission devices, wherein the first communication device, when detecting switching information from the first transmission device, notifies the first transmission device of first switching notification information and notifies the second transmission device of second switching notification information, the first transmission device stops relaying the first signal to the first communication device in response to the first switching notification information from the first communication device, and the second transmission device starts to relay the second signal to the first communication device in response to the second switching notification information from the first communication device.

Transmission system, transmission device, and transmission method

An optical transmission apparatus for transmitting wavelength-multiplexed light, the optical transmission apparatus includes: an optical transmitter configured to transmit light of a third wavelength to be arranged between a first wavelength and a second wavelength adjacent to the third wavelength in the wavelength-multiplexed light, and a controller configured to control a bandwidth of the light of the third wavelength to be arranged in a first bandwidth narrower than a spacing between the first wavelength and the second wavelength.

Optical transmission apparatus, optical transmission system, and transmission wavelength control method

A wavelength selective switch is configured to demultiplex WDM light input from an input side for each wavelength, to supply the demultiplexed signal lights to deflectors corresponding to the demultiplexed wavelength, and to control the deflector to selectively output the demultiplexed signal lights to an output side, in which monitor light having at least a wavelength included in the WDM light is input to the wavelength selective switch from the output side of the wavelength selective switch, and the monitor light input from the output side of the wavelength selective switch is monitored, the monitor light being propagated in a direction opposite to a propagation direction of the signal lights each having the demultiplexed wavelength in the wavelength selective switch and being output to the input side of the wavelength selective switch.

Wavelength selective switch, variable dispersion compensator, optical transmission apparatus, and optical transmission system

A transmission system is provided that recognizes occurrence of a fault efficiently so that the workability and quality of service can be improved. An optical amplifier part amplifies an optical main signal. A fault occurrence recognizing part detects a pump light used for an opposing device via an optical fiber transmission line to which an optical main signal is sent by the repeater. If the pump light is not detected, the fault occurrence recognizing part recognizes occurrence of a fault. A light cutoff control part stops the optical amplifying part outputting an amplified signal so that the light cutoff control in only one of two directions is performed when a fault occurs.

Transmission device and repeater

A non-interruptive protection switching device which performs protection switching in a more efficient and robust way. The device has a working-channel signal storage unit to store data signals received through a working channel. Multiframe synchronization timings are detected by a working-channel multiframe synchronization controller, which provides a working-channel multiframe sync detection pulse signal when the main signals are in a normal condition and stops it when the channel is disrupted. A working-channel write controller controls every write access to the working-channel signal storage unit, generating a write pulse signal therefor. The working-channel write controller also produces working-channel write phase data by identifying a phase difference of the detected multiframe synchronization timing with respect to a reference phase signal. The generation of this write pulse signal is based on the multiframe sync detection pulse signal when the working-channel multiframe sync detection pulse signal is available, or on a free-running timebase when it is stopped. The stored data in the working- and protection-channel signal storage units are read out simultaneously, under the control of a read controller which produces read pulses from the write phase data.

Non-interruptive protection switching device and network system using the same

A transmission device and an integrated circuit improved in quality and reliability of digital transmission control. A memory stores an input signal, write address generating means generates a write address for writing in the memory, and read address generating means generates a read address for reading from the memory. Phase state monitoring means monitors a transition from a steady phase state in which writing/reading in/from the memory is normally performed or from a startup state to a coincident phase state in which address values of the write and read addresses coincide with each other or to an unstable phase state in which a phase fluctuation margin is one-sided. When the coincident phase state or the unstable phase state is detected, reset signal output means outputs a reset signal to the write and read address generating means such that the phase relation between the write and read addresses is brought to an optimum phase relation.

Growing community of inventors

Ota, Japan

Yuji Kamura