Fujitsu Corporation

Nippon Kokan Kabushiki Kaisha

Osamu Takeuchi

Yasuhiko Aoki

Masahiro Shioda

Taku Saito

Katsumi Fukumitsu

Hirofumi Araki

Takeshi Hoshida

Hisao Nakashima

Kosuke Komaki

Hirotaka Morita

Hideaki Arao

Daijiro Tanaka

Hiroyuki Ohgaki

Toru Katagiri

Nobukazu Koizumi

Hiroaki Nishio

Tsuneo Miyashita

Satoru Saitoh

Yohei Koganei

Hiroyuki Honma

Yoshitaka Taki

Kanji Naito

Hideyuki Matsuura

Hideyuki Yoshikoshi

Tomoyoshi Fujimori

Shoichi Murakami

Hayato Furukawa

Masaki Nakada

Yuuji Kamura

Hikari Mochizuki

An optical receiver including: a digital filter that performs spectral shaping on a signal; an analyzer that analyzes a spectrum waveform of the signal; a determiner that determines, based on an analysis result by the analyzer, whether the spectrum waveform of the signal is a Nyquist waveform on the basis of a Nyquist first reference; and a controller that stops the spectral shaping of the signal to be performed by the digital filter when the spectrum waveform of the signal is not the Nyquist waveform as a result of the determination by the determiner, and controls a filter coefficient of the digital filter based on the spectrum waveform of the signal when the spectrum waveform of the signal is the Nyquist waveform as the result of the determination by the determiner.

Optical receiver and signal processing method

A signal processing device that processes a digital signal formed by sampling an electric signal using a clock signal, the electric signal being obtained by converting an optical signal inputted from a transmission line, the signal processing device includes: a first chromatic dispersion compensator that compensates a waveform distortion caused by a chromatic dispersion with respect to the digital signal; a first nonlinear optical effect compensator that compensates a waveform distortion caused by a nonlinear optical effect with respect to one signal outputted from the first chromatic dispersion compensator; and a controller that detects a phase fluctuation of other signal outputted from the first chromatic dispersion compensator, and controls the clock signal based on the detected phase fluctuation.

Signal processing device and signal processing method

An optimization unit in an optical receiver divides a symbol region out of a plurality of symbol regions into which signal points that specifies symbol information included in an optical signal are classified, into a plurality of division regions from the symbol center coordinate of the symbol region. Moreover, the optimization unit accumulates the signal points of the symbol information for every division region in the symbol region. Furthermore, based on the accumulated number of signal points for every division region, the optimization unit controls the average length of a phase estimation unit when the phase noise of the optical signal is calculated.

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

An optical transceiver converts a received optical signal to an electric signal and converts the electric signal to a digital signal, and has an adaptive equalizer to adaptively equalize the digital signal, a synchronization part to synchronize a first polarized wave and a second polarized wave contained in the adaptively equalized digital signal and having polarization axes perpendicular to each other, and a symbol offset determination part to determine an amount of symbol offset between the first polarized wave and the second polarized wave based upon symbol synchronization information of the first polarized wave and the second polarized wave supplied from the synchronization part, the symbol offset determination part being configured to repeat determination of the amount of symbol offset and restart the adaptive equalizer until the symbol offset is minimized.

Optical receiver and signal processing method for optical receiver

A method of tap coefficient correction includes: obtaining a synchronization symbol difference between a first polarization and a second polarization orthogonal to the first polarization; obtaining a delay amount of each of the first polarization and the second polarization in an adaptive equalizer; calculating, in a case where a horizontal axis represents a tap number and a vertical axis represents a tap coefficient and a tap number or a nearest tap number with which an area of a drawn figure is halved is set as a gravity center of tap coefficients, a correction reference gravity center of the tap coefficients set in the adaptive equalizer, based on the synchronization symbol difference and the delay amount; and performing a correction of shifting an entire tap coefficients in units of symbol to cause the correction reference gravity center to be closest to a tap center.

Adaptive equalizer tap coefficient correction method and optical receiver

A digital coherent optical receiver includes a processor that is operative to separate electric signals obtained by converting an optical signal into a horizontal signal component and a vertical signal component; to generate a histogram of the horizontal signal component and the vertical signal component as outputs of the equalizing filter; and to determine a presence/absence of local convergence based on distribution of the histogram of the horizontal signal component and the histogram of the vertical signal component.

Digital coherent optical receiver, adaptive equalizer, and digital coherent optical communication method

An optical transmission system transmits an optical signal of multi-level modulation. In a transmitter module, a data string in a specified frame is rearranged into a plurality of logical lanes. A lane ID, which specifies in what logical lane out of the plurality of logical lanes a start of the data string is arranged, is assigned to a non-scrambled area in an overhead portion of the frame. The lane ID corresponding to one of the plurality of logical lanes is different from the lane IDs corresponding to the other remaining logical lanes. The optical signal is generated using the data string rearranged into the plurality of logical lanes. In a receiver, the lane ID is detected according to a majority method. The inversion of bits and the swapping of lanes are detected using the lane ID and compensated.

Optical transmission system and optical transmission method

A frame generating apparatus includes an optical-transport-network frame generator configured to generate an optical transport network frame from a client signal; and a frame decomposer configured to perform serial-parallel conversion on the optical transport network frame to generate a plurality of virtual lanes, where the optical-transport-network frame generator arranges frame synchronization bytes and virtual lane identifiers in an overhead area and/or a fixed stuff part so that a frame synchronization byte and a virtual lane identifier are arranged in each virtual lane.

Frame generating apparatus, optical transmission system, frame generating method, and optical transmission method

An optical receiver includes: a waveform distortion compensator to perform an operation on digital signal representing an optical signal generated by an A/D converter to compensate for waveform distortion of the optical signal; a phase detector to generate phase information representing sampling phase of the A/D converter; a phase adjuster to generate digital signal representing an optical signal in which the sampling phase of the A/D converter is adjusted from an output signal of the waveform distortion compensator using the phase information; a demodulator to generate a demodulated signal from the output signal of the phase adjuster; a phase controller to control the sampling phase of the A/D converter; a peak detector to detect a peak value of the phase information while the sampling phase of the A/D converter is controlled by the phase controller; and a compensation controller to control the waveform distortion compensator using the peak value.

Optical receiver

An optical transmission apparatus including a transmitting OTL processor to rearrange a data string stored in a frame into a plurality of logical lanes, and set a lane ID used to identify in which logical lane a beginning of the data string is arranged among the plurality of logical lanes in a non-scramble area in an overhead of the frame, and a receiving OTL processor to respectively identify the lane IDs included in the data string in the respective physical lanes rearranged, determine a generation state of a bit inversion and a lane replacement for each physical lane, compensate the bit inversion and the lane replacement so that the data string in the respective physical lanes becomes same state as the data string in the respective logical lanes, based on the identified result, and rearrange the compensated data string in the respective logical lanes so as to regenerate the frame.

Optical transmission apparatus and method

A frame generating device includes an inserting portion and an accommodating portion. The inserting portion inserts a first fixed stuff byte and a second fixed stuff byte into a payload area of an OTU frame, the first fixed stuff byte being of (8+10n ('n' is zero or a given positive integer))&#xd7;4 rows, the second fixed stuff byte being of a given byte&#xd7;4 rows, the given byte being equal to zero or more and being equal to (24&#x2212;10n) or more. The accommodating portion accommodates Ethernet signal in the payload area other than the first fixed stuff byte and the second fixed stuff byte.

Frame generating method

In a path status monitoring method and device which can enhance or reduce a band more rapidly, for example, SONET frames FR serially connected over 32 frames to which frame Nos. FN ('0'-'31')) are assigned are cyclically generated respectively for paths P-Pin a cycle T(=64 ms). After output timing delays T-Tof the frames FR are shifted by an optimal delay interval D (=21 ms) between the paths P-Pbased on the number of the paths &#x201c;3&#x201d;, the output timing delays Tand Tare restored by preliminarily obtained transmission delays for the paths Pand Pto the path P. When the frames FR are transmitted through each of the paths P-P, statuses (path statuses MST) where a reception fault has occurred in each of the paths P-Pare collected to be stored in the frame whose frame No. FN=&#x201c;0&#x201d;.

Path status monitoring method and device

A multiple frame rate synchronous detecting apparatus for synchronous-detecting received serial data having one frame rate among a plurality of predetermined frame rates is provided. The apparatus comprises a serial-to-parallel converter for serial-to-parallel converting the received serial data with matching with highest frame rate, a coincidence detector for comparing a portion of the converted parallel data corresponding to a predetermined region defined based on the frame rate, with a pattern for synchronous detection to detect coincidence, and a synchronous determiner for determining to have been synchronized with the frame rate when a periodic cycle of the coincidence detection is the same as a previous one.

Multiple frame rate synchronous detecting method and apparatus

A packet transmission system is disclosed. The system serves between terminal apparatuses that include a supervisory control circuit configured to transmit a supervisory signal in a direction opposite to the transmission direction of a main signal on each of and both of an upstream circuit and a downstream circuit. The packet transmission system transmits overhead information of a packet frame of the main signal of the upstream circuit and the downstream circuit using the supervisory control circuit of the downstream circuit and the upstream circuit, respectively.

Packet transmission system and a terminal apparatus

A blade-type optical transmission apparatus includes a plurality of main-signal blades, each of which is provided with an external optical signal interface unit, a cross-connect unit, and an internal optical signal interface unit, a blade enclosure in which the plurality of main-signal blades are enclosed, and a back plane which is situated inside the blade enclosure and provides a ring connection for the internal optical signal interface unit between the main-signal blades.

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Kawasaki, Japan

Osamu Takeuchi