公开(公告)号：US10574350B2

公开(公告)日：2020-02-25

申请号：US16367384

申请日：2019-03-28

申请人： Fujitsu Limited

发明人： Yangyang Fan ,  Liang Dou

IPC分类号： H04B10/00 ,  H04B10/07 ,  H04B10/516 ,  H04B10/60 ,  H04B10/564 ,  H04B10/50 ,  H04B10/69 ,  H04B10/61 ,  H04B10/079

摘要： 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.

公开(公告)号：US11626930B2

公开(公告)日：2023-04-11

申请号：US17564726

申请日：2021-12-29

申请人： FUJITSU LIMITED

发明人： Jingnan Li ,  Yangyang Fan ,  Zhenning Tao

IPC分类号： H04B10/06 ,  H04B10/61

摘要： A polarization recovery apparatus, a method thereof and an optical receiver. The method includes: performing adaptive equalization processing and polarization recovery on a received signal, wherein a polarization state of the received signal, after the adaptive equalization processing and polarization recovery being performed, is aligned with a principal axis of polarization of an optical receiver.

公开(公告)号：US10903911B2

公开(公告)日：2021-01-26

申请号：US16730223

申请日：2019-12-30

申请人： Fujitsu Limited

发明人： Yangyang Fan ,  Zhenning Tao

IPC分类号： H04B10/61 ,  H04B10/079

摘要： Embodiments of this disclosure provide an apparatus and method for estimating polarization skew. The method includes: acquiring a plurality of coefficients of an adaptive equalizer of a receiving device; the plurality of coefficients of the adaptive equalizer include at least polarization skew of a transmitting device and polarization skew of the receiving device; and calculating the polarization skew of the transmitting device and the polarization skew of the receiving device according to the plurality of coefficients of the adaptive equalizer.

公开(公告)号：US10404380B2

公开(公告)日：2019-09-03

申请号：US15720576

申请日：2017-09-29

申请人： Fujitsu Limited

发明人： Yangyang Fan ,  Zhenning Tao

IPC分类号： H04B10/516 ,  H04B10/61 ,  H04J14/06 ,  H04B10/69 ,  H04B10/2575

摘要： Embodiments of this disclosure provide a compensation apparatus for an offset drift, a received signal recovery apparatus and a receiver, in which estimation and compensation of an offset drift are directly performed at a receiver end, with no need of extra provision of an offset control circuit at a transmitter end, so that the system is simple in structure, applicable to various modulation formats, wide in applicability, and is able to meet demands for high-order modulation formats. And furthermore, by equalizing a received signal and performing phase recovery on a frequency difference and phase noises, information on offset points of a modulator of the transmitter end may be accurately separated, thereby accurately compensating for the offset drift of the modulator of the transmitter end.

公开(公告)号：US11463172B2

公开(公告)日：2022-10-04

申请号：US17491999

申请日：2021-10-01

申请人： Fujitsu Limited

发明人： Jingnan Li ,  Yangyang Fan ,  Zhenning Tao

IPC分类号： H04B10/00 ,  H04B10/2569 ,  H04B10/2513 ,  H04B10/2507 ,  H04J14/06

摘要： An apparatus and method to monitor a polarization change by inserting pilot signals in a transmission signal and converting the pilot signals in the receiving signal from a Jones space into a Stokes space. A velocity of a polarization change of the optical link is estimated by using the Stokes vectors of the pilot signals, thereby directly and accurately estimating the polarization change of the optical link. Moreover, estimation of the velocity of the polarization may be applicable where rotation of state of polarization and polarization-dependent loss coexist in an optical link.

公开(公告)号：US10917171B2

公开(公告)日：2021-02-09

申请号：US16577680

申请日：2019-09-20

申请人： Fujitsu Limited

发明人： Ke Zhang ,  Zhenning Tao ,  Yangyang Fan

IPC分类号： H04B10/079

摘要： A method and apparatus of fiber nonlinear noise monitoring and an optical receiver is provided. The method includes: acquiring a training set including at least two received signal samples obtained after a transmitting signal passes different simulation transmission scenarios, calculating amplitude noise feature values after a digital signal processing, calculating statistics values of fiber nonlinear noises, marking the amplitude noise feature values; taking the amplitude noise feature values as input of a noise monitoring model, taking marks to which the amplitude noise feature values correspond as target output, and training the noise monitoring model according to samples in the training set, so as to obtain a trained noise monitoring model, and inputting a plurality of amplitude noise feature values of received signals to be monitored into the trained noise monitoring model, so as to obtain statistics values of fiber nonlinear noises to which the received signals to be monitored correspond.

公开(公告)号：US10892962B2

公开(公告)日：2021-01-12

申请号：US16136817

申请日：2018-09-20

申请人： FUJITSU LIMITED

发明人： Ke Zhang ,  Xiaofei Su ,  Yangyang Fan ,  Zhenning Tao

IPC分类号： H04L12/26 ,  H04B10/079 ,  H04L7/00

摘要： An inter-channel linear crosstalk estimation method and apparatus and a communication system are disclosed. The apparatus includes: an adjacent channel synchronizing unit configured to synchronize adjacent channel information inserted with a cyclic training sequence in a received signal, to determine a time window of occurrence of the cyclic training sequence; a time domain cutoff unit configured to perform time cutoff on center channel information in the received signal according to the time window of occurrence of the cyclic training sequence, to obtain center channel information within the same time window as the cyclic training sequence; a filtering unit configured to filter the center channel information within the time window, and reserve center channel information containing linear crosstalk from an adjacent channel; and a linear crosstalk estimating unit configured to estimate a magnitude of linear crosstalk leaking into the center channel by using a cyclic characteristic of the cyclic training sequence.

公开(公告)号：US10116388B2

公开(公告)日：2018-10-30

申请号：US15375714

申请日：2016-12-12

申请人： FUJITSU LIMITED

发明人： Yangyang Fan ,  Zhenning Tao ,  Liang Dou

IPC分类号： H04B10/25 ,  H04B10/2507 ,  H04B10/079 ,  H04B10/58

摘要： 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.

公开(公告)号：US11777613B2

公开(公告)日：2023-10-03

申请号：US17564736

申请日：2021-12-29

申请人： FUJITSU LIMITED

发明人： Jingnan Li ,  Yangyang Fan ,  Zhenning Tao

IPC分类号： H04B10/61 ,  H04J14/06

CPC分类号： H04B10/6166 ,  H04B10/6162 ,  H04J14/06

摘要： A polarization change tracking apparatus, a processing apparatus for a received signal and methods thereof. The polarization change tracking method includes: estimating a polarization change speed in a link according to a received signal; setting a response coefficient of polarization tracking according to a relationship between an estimated polarization change speed and a predetermined value, to make a response of polarization tracking and a response of adaptive equalization be consecutive; and performing compensation for polarization change on the received signal according to a set response coefficient of polarization tracking.

公开(公告)号：US11329724B2

公开(公告)日：2022-05-10

申请号：US17321850

申请日：2021-05-17

申请人： Fujitsu Limited

发明人： Yangyang Fan ,  Jingnan Li ,  Zhenning Tao

IPC分类号： H04B10/25 ,  H04J14/06 ,  H04B10/2507

摘要： A state of polarization tracking recovery method and apparatus. The apparatus at least includes a processor configured to fit Stokes vectors to which predetermined symbols correspond of two states of polarization in a received dual-polarization multiplexing optical signal on a Poincare sphere to obtain a fitted plane. The processor calculates a compensation matrix for polarization-dependent loss (PDL) in a Jones space by moving a center of the fitted plane to the origin of the Poincare sphere, and calculates a demultiplexing matrix used for polarization demultiplexing in a Jones space by rotating the fitted plane with the center being moved to the origin until a normal vector of the fitted plane is parallel with a first axis of the Stokes space and rotating the fitted plane with the center being moved to the origin to a plane constituted by a second axis and a third axis of the Stokes space.