Fujitsu Corporation

Yoshitaka Nomura

Hisao Nakashima

Takeshi Hoshida

Tomofumi Oyama

Yuichi Akiyama

Takahito Tanimura

Nobukazu Koizumi

Yoshio Hirose

Yi Ge

Yasuo Ohtomo

Daisuke Sasaki

A signal processing device includes: a memory; and a processor coupled to the memory and configured to: compensate an electric field signal representing an electric field component in an optical signal input from a transmission channel for an optical frequency offset between light sources on a transmission side and a reception side of the optical signal based on a compensation value; calculate an estimated value of the optical frequency offset from data having a fixed pattern in the electric field signal; generate a plurality of candidates for the compensation value from the estimated value; calculate power of the optical signal compensated for the optical frequency offset based on each of the plurality of candidates; and select an initial value of the compensation value from the plurality of candidates based on the power of the optical signal.

Signal processing device and transmission device

A transmission device includes a receiver configured to receive a frame signal including synchronization data, main signal data, and an error correction code, a compensator configured to compensate for distortion of the frame signal based on a compensation coefficient, a detector configured to detect synchronization timing of the frame signal from the synchronization data; a corrector configured to correct an error of the frame signal after the distortion is compensated, based on the error correction code according to the synchronization timing, a generator configured to generate a replica signal from the frame signal after the error is corrected by the corrector, based on the synchronization timing, the replica signal corresponding to the frame signal before the distortion is compensated, and an update processor configured to update the compensation coefficient based on the replica signal and the frame signal before the distortion is compensated.

Transmission reception device and distortion compensation method

Provided is an imbalance compensation device that compensates for an imbalance between an in-phase component and a quadrature-phase component of a signal, the imbalance compensation device including: an extracting unit that extracts a signal component in an upper sideband or a signal component in a lower sideband from the signal; a measuring unit that measures power of the signal component in the upper sideband or the signal component in the lower sideband extracted by the extracting unit; and an adjusting unit that adjusts a parameter related to the imbalance, in accordance with the power measured by the measuring unit.

Imbalance compensation device, transmission device, and imbalance compensation method

There is provided an optical transmitter including a modulator, a signal generator configured to generate in-phase or anti-phase skew adjustment signals that are identical in amplitude and frequency as signals to be input into an I axis and a Q axis of the modulator, a skew adjuster configured to perform skew adjustment upon the skew adjustment signals, a light source configured to enter light into the modulator, a monitor configured to monitor light that has been modulated using the skew adjustment signals and output from the modulator, a power detector configured to detect power of monitor light, and a controller configured to determine a skew adjustment amount with which average power of the monitor light is at a maximum or minimum value as an optimum skew adjustment value while changing a skew adjustment amount of the skew adjuster.

Optical transmitter and skew compensation method

A signal processing device processes an electric field information signal indicating a polarization multiplexed optical signal in which different modulation formats are used. A first optical signal transmitted in a first polarization component and a second optical signal transmitted in a second polarization component are multiplexed in the polarization multiplexed optical signal. The signal processing device includes a generator and a compensation circuit. The generator selects the first polarization component or the second polarization component based on modulation formats of the first and second optical signals, and generates a compensation value for compensating for an electric field information signal of a selected polarization component based on the electric field information signal of the selected polarization component. The compensation circuit compensates for electric field information signals of the first and second polarization components using the compensation value generated by the generator.

Signal processing device used in optical receiver and signal processing method

An optical reception apparatus includes an equalization processor, an extraction unit, a first ratio calculator, and an instruction transmitter. The equalization processor suppresses fluctuations in amplitude of an electrical signal obtained by converting an optical signal including a plurality of pilot symbols subjected to BPSK modulation by an optical transmission apparatus. The extraction unit extracts the pilot symbols from the electrical signal with suppressed fluctuations in amplitude. The first ratio calculator calculates a ratio of an amplitude component to a phase component of each of the pilot symbols extracted by the extraction unit. The instruction transmitter transmits information relating to skew adjustment based on the ratio of the amplitude component to the phase component calculated by the first ratio calculator for each of different control values to the optical transmission apparatus.

Optical reception apparatus, optical transmission apparatus, optical communication system, and skew adjusting method

A signal processing device includes digital signal processing circuits. Each of the digital signal processing circuits includes: a regeneration circuit that regenerates a bit stream front an electric field information signal of an optical signal; an error correction circuit that corrects an error in the bit stream; an encoder circuit that generates an encoded bit stream from received data; and a generation circuit that generates an electric field information signal from the encoded bit stream. An electric field information signal or a bit stream is given from a regeneration circuit, an encoder circuit or a generation circuit in a first digital signal processing circuit to a second digital signal processing circuit. A regeneration circuit, an error correction circuit or a generation circuit in the second digital signal processing circuit processes the electric field information signal or the bit stream given from the first digital signal processing circuit.

Digital signal processing circuit and signal processing device that includes a plurality of digital signal processing circuits

There is provided a transmission apparatus configured to transmit an optical signal by using a plurality of subcarriers, the transmission apparatus includes: a plurality of modulators, a modulator of the plurality of modulators configured to be capable of changing a modulation format corresponding to a subcarrier of the plurality of subcarriers; a controller configured to control the modulation format for the modulator so as to use a first modulation format and a second modulation format for two or more subcarriers among the plurality of subcarriers and include subcarriers that are different in at least one of a first timing and a second timing of the first modulation format; and a multiplexer configured to multiplex signals modulated by the plurality of modulators.

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Shinagawa, Japan

Yoshitaka Nomura