Fujitsu Corporation

Alibaba (china) Co., Ltd.

Liang Dou

Zhenning Tao

Ying Zhao

Yangyang Fan

Huihui Li

Takeshi Hoshida

Shoichiro Oda

Chongjin Xie

Taku Saito

Xiaofei Su

Cheng Ju

Jingchi Cheng

Pak Tao Lau

A method for calculating configuration of an optical transmission network includes: acquiring an initial value of an input power of an optical cable; based on the initial value, obtaining an output power of each channel at an end of a section of the optical cable according to a loss of the optical cable; taking the output power of each channel at the end of the section as a boundary condition to calculate the input power of each channel at the section based on an amount of optical power transferred from a high-frequency channel to a low-frequency channel due to an SRS effect; and calculating a first parameter value of an optical amplifier of the section using the input power of each channel at the section and the output power of each channel at the end of a preceding section of the section.

Method and apparatus for calculating configuration of optical transmission network, and optical transmission network system

An estimating apparatus for bias drift of a transmitting end modulator, a compensating apparatus, a receiver and a method are disclosed. Estimation and compensation of the bias drift are performed directly at the receiving end according to phase recovered received signals, with no need of providing an extra bias control circuit at the transmitting end. Estimating and compensating for the bias drift includes recovering received signals by removing a frequency difference and a phase difference between a transmitting end laser and a receiving end laser producing phase recovered received signals, estimating the bias drift of the transmitting end modulator according to the phase recovered received signals and compensating the bias drift of the transmitting end modulator in a receiver.

Estimating apparatus for bias drift of transmitting end modulator, compensating apparatus and receiver

An apparatus and method for processing a frequency offset of a pilot and a receiver where the includes: calculating a correlation function of a channel by using a receiving or received signal and a correlation length; calculating a phase to which the correlation length corresponds according to the correlation function; and calculating a corresponding slope according to phases to which at least two correlation lengths correspond when the phase to which the correlation length corresponds is greater than 2&#x3c0;, and estimating a frequency offset of a pilot of the channel based on the slope. Hence, estimation of a frequency offset of a pilot may be accurately achieved, thereby accurately judging channel spacing.

Apparatus and method for processing a frequency offset of a pilot and receiver

A method and apparatus estimating direct current bias of an optical modulator and a receiver. The method includes: performing signal processing to obtain a phase noise compensated signal, extracting a receiving signal component based on the phase noise compensated signal, removing the receiving signal component from the phase noise compensated signal, and calculating a received signal power based on the signal with the receiving signal component being removed. The method includes calculating a direct current bias of the optical modulator based on the receiving signal component, the received signal power and a drive signal power of the optical modulator.

Method and apparatus for estimating direct current bias of optical modulator and receiver

A signal processing apparatus and method for monitoring channel spacing which may be configured in a receiver and includes: a first determining unit to determine a frequency range of a pilot of a center channel and a frequency range of a pilot of a neighboring channel using a receive signal; a second determining unit to determine a center channel frequency offset of the center channel pilot according to the center channel frequency range, and determine a frequency offset of the neighboring channel pilot according to the neighboring channel frequency range; and a third determining unit to determine channel spacing between the center channel and the neighboring channel according to the center channel frequency offset, the neighboring channel frequency offset and a frequency of a pilot signal at a transmitter side.

Signal processing apparatus, apparatus and method for monitoring channel spacing and system

Embodiments of the present disclosure provide a signal processing apparatus, a signal transmitting apparatus and a receiver, which are adapted for a frequency division multiplexing system having a high-order modulation format. A receiver having a high-magnification sampling rate by inserting a pilot signal between neighboring subcarriers at a transmitter side, calculating a laser phase noise according to a phase of the pilot signal at a receiver side, and performing down-sampling and equalization processing after performing carrier phase recovery according to the laser phase noise, so that a laser phase noise having a wide frequency may be accurately compensated, thereby having a relatively powerful carrier phase recovery ability.

Signal processing apparatus, signal transmitting apparatus and receiver

Embodiments of this disclosure provide a signal transmission apparatus, a carrier phase recovery apparatus and method. By inserting phase modulation signals with variable amplitudes into data modulation signals and performing carrier phase recovery on received signals at a receiving end according to the phase modulation signals, the apparatuses and methods are applicable to communications systems of various modulation formats and are compatible with existing communications systems, and calculation complexity is relatively low. Furthermore, as the amplitudes of the inserted phase modulation signals are variable, the phase modulation signals may be flexibly configured in data modulation signals, to lower redundancy and influence on the system capacity is relatively small.

Signal transmission apparatus, carrier phase recovery apparatus and method

Embodiments of the present disclosure provide a monitoring apparatus for an optical signal to noise ratio, a signal transmission apparatus and a receiver. White noise power of received signals is calculated according to noise power and power of pilot signals of the received signals in different polarization states, and influence of a nonlinear noise is excluded, thereby accurately estimating an optical signal to noise ratio, for example, with a calculation process being simple and an application range being relatively wide.

Monitoring apparatus for optical signal to noise ratio, signal transmission apparatus and receiver

Embodiments of this disclosure provide an apparatus and method for generating a transmitting sequence, a training sequence synchronization apparatus and method, an apparatus and method for estimating channel spacing and a system. The training sequence synchronization apparatus includes: a delay correlation processing unit configured to parallelly perform autocorrelation operations of different delay amounts on a receiving sequence containing a periodic training sequence to obtain multiple parallel correlation sequences; a superimposition processing unit configured to perform a superimposition operation on the multiple parallel correlation sequences to obtain a synchronization correlation sequence; and a synchronization extracting unit configured to perform a synchronization position extraction on the synchronization correlation sequence to obtain a synchronization position of the training sequence. With the embodiments of this disclosure, anti-noise performance of the training sequence may be enhanced.

Apparatus and method for generating transmitting sequence, training sequence synchronization apparatus and method, apparatus and method for estimating channel spacing and system

Provided is an apparatus for measuring a filtering characteristic, a pre-equalizer and an optical communication equipment where the apparatus includes: a first processing unit configured to determine a filtering characteristic of a receiving end, or determine a joint response of a filtering characteristic of a transmitting end and the filtering characteristic of the receiving end, in a spectrum of a receiving signal obtained after a first measurement signal and a second measurement signal pass through respective filtering modules, according to a nonoverlapped spectral part of the first measurement signal and the second measurement signal. The filtering modules through which the first measurement signal passes include a transmitting end filtering module and a receiving end filtering module, the filtering module through which the second measurement signal passes include the receiving end filtering module.

Apparatus for measuring a filtering characteristic, pre-equalizer and optical communication equipment

A method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment. The apparatus for measuring a filtering characteristic includes: a first processing unit configured to determine a filtering characteristic of a receiving end according to an amplitude of a receiving signal obtained after a measurement signal passes through a transmitting end filtering module and a receiving end filtering module at provided different frequency offsets of a transmitting laser of a transmitting end and a local laser of the receiving end.

Method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment

An apparatus and method for measuring frequency response characteristics of an optical transmitter and an optical receiver where the apparatus includes: a generating unit configured to generate a driving signal for driving the modulator of the optical transmitter, which comprises at least two frequencies; and a calculating unit configured to respectively calculate the frequency response characteristics of the optical transmitter and the optical receiver according to output signal components in output signals of the optical receiver corresponding to at least two detection signal components of identical amplitudes and different frequencies in detection signals. The frequency response characteristics of the optical transmitter and the optical receiver may be obtained, the amplitude responses and phase responses in the frequency response characteristics may be respectively obtained, and the measurement results are accurate and reliable.

Apparatus and method for measuring frequency response characteristics of optical transmitter and optical receiver

A method and apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment. The method includes: obtaining a receiving signal after two measurement signals of different spectral ranges pass through different filtering modules and are received at the same time at a receiving end; and determining a part of a filtering characteristic of a receiving end and a part of a joint response according to a nonoverlapped spectral part of the two signals in the spectrum of the receiving signal.

Apparatus for measuring a filtering characteristic, pre-equalizer and communication equipment

Embodiments of the present disclosure provide a calculating apparatus and method for nonlinear weighting coefficient. The calculating apparatus for nonlinear weighting coefficient includes: an approximation processing unit configured to use a rational function to perform approximation processing on a link loss/gain function in intra-channel nonlinear distortion estimation; and a coefficient calculating unit configured to calculate a nonlinear weighting coefficient in the nonlinear distortion estimation by using the approximated link loss/gain function and a large dispersion approximation, to obtain an analytical closed solution of the nonlinear weighting coefficient. With the embodiments of the present disclosure, a weighting coefficient of high precision may be obtained, thereby performing high-precision estimation on nonlinear distortion in case of loss.

Calculating apparatus and method for nonlinear weighting coefficient

Embodiments of this disclosure provide an apparatus and method for estimating a frequency offset, an apparatus and method for estimating a channel spacing and a system. The apparatus for estimating a frequency offset includes: a synchronization extracting unit configured to perform a training sequence synchronization extraction on a receiving sequence containing a periodic training sequence to obtain the training sequence; a delay correlation processing unit configured to parallelly perform autocorrelation operations of different delay amounts on the training sequence to obtain multiple parallel correlation sequences; a superimposition processing unit configured to perform a superimposition operation on the multiple parallel correlation sequences to obtain a single sequence; and a frequency offset estimating unit configured to determine a frequency offset according to a phase of a synchronization position of the single sequence in the training sequence. With the embodiments of this disclosure, anti-noise characteristic of the frequency offset estimation may be improved.

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Beijing, China

Liang Dou