Abstract: 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.

Abstract: 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.

Abstract: An apparatus and method for monitoring a change of a polarization state resulted from an optical link and optical receiver is provided. By combining zero-frequency response matrices and phase information on the received signal at two moments, a change matrix of the zero-frequency channel response matrices at the two moments is obtained, and a parameter characterizing a polarization state change induced by the optical link is determined according to the change matrix, which may dynamically monitor in real-time manner the polarization state change induced by the optical link, irrelevant to the polarization state of an input signal of the optical link. Due to the combination of the zero frequency response matrices and the phase information, response of the optical link may be completely reflected, for more accurate monitoring the polarization state. In addition, there is no need to add additional hardware and controls, thereby simplifying the structure and saving cost.

Abstract: Embodiment of the present disclosure provide an apparatus and method to monitor a change of a polarization state resulted from an optical link and an optical receiver, in which by obtaining a change matrix of response matrices at two moments, and determining a parameter characterizing a change of a polarization state resulted from an optical link according to feature values of a change matrix in a Stokes space corresponding to the response matrices. The change of the polarization state resulted from the optical link is dynamically monitored in a real-time manner, independent of a polarization state of an input signal of the optical link, and no extra hardware and control may be needed.

Abstract: A harmonic distortion separation method, nonlinear character determination method, apparatus and system where a phase difference between an inherent harmonic and a generated harmonic is determined by using multiple groups of input power, output power and fundamental magnitudes of a memoryless nonlinear transfer function of a nonlinear model of a system to be measured, and power of a harmonic generated by the system to be measured is separated by using the phase difference. In an embodiment, the phase difference between the inherent harmonic and the generated harmonic is first determined by using an assumption that a model coefficient is a constant according to the set nonlinear model, then the harmonic separation is performed by using the phase difference, and the power of the harmonic generated by the system to be measured is calculated.

Abstract: Embodiments of this disclosure provide a phase noise compensation apparatus and method and a receiver, in which modified signals are determined according to estimated values of an imperfection parameter of a transmitter and training sequence signals in transmission signals, and phase noises of the received signals are determined according to the modified signals, hence, an effect of the imperfection parameter of the transmitter on the phase noise is taken into account, and the phase noise may be accurately estimated, thereby performing compensation on the phase noise, and ensuring a transmission efficiency and performance of the system.

Abstract: Embodiments of this disclosure provide an impairment monitoring apparatus, impairment monitoring and compensating system and method. As a parameter of a impairment of a receiver end and/or a parameter of an impairment of a transmitter end is/are determined according to a preset period or a preset condition to perform compensation or calibration, complexity of calculation and power consumption of the system may be efficiently lowered. And as the parameter of the impairment of the receiver end and the parameter of the impairment of the transmitter end are not changed rapidly, determining these parameters according to the preset period or the preset condition to perform compensation or calibration will not affect an effect of the compensation or calibration, thereby ensuring a performance of the system.

Abstract: An estimation apparatus for IQ imbalance of an optical transmitter, a compensation apparatus for IQ imbalance of an optical transmitter and electronic equipment; wherein, estimation and compensation of IQ imbalance of an optical transmitter are performed by directly using an estimation model based on a transform matrix of received signals and transmitted signals, therefore, a phase offset shift may be estimated accurately, and precision of estimation of drifts of various angles is ensured, furthermore, accurate recovery of the constellation diagram of received signals is achieved.

Abstract: 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?, 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.

Abstract: Embodiment of the present disclosure provide an apparatus and method to monitor a change of a polarization state resulted from an optical link and an optical receiver, in which by obtaining a change matrix of response matrices at two moments, and determining a parameter characterizing a change of a polarization state resulted from an optical link according to feature values of a change matrix in a Stokes space corresponding to the response matrices. The change of the polarization state resulted from the optical link is dynamically monitored in a real-time manner, independent of a polarization state of an input signal of the optical link, and no extra hardware and control may be needed.

Abstract: 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.

Abstract: Embodiments of this disclosure provide an apparatus and method for monitoring a polarization dependent loss, a receiver and a communication system. The apparatus for monitoring a polarization dependent loss includes: a first processing unit configured to process received optical signals, to obtain a first correlation matrix of noise signals in the received optical signals and a second correlation matrix of second signals or other signals in the received optical signals other than first signals or spectral feature signals having predetermined spectral features; a matrix subtraction unit configured to subtract the second correlation matrix by the first correlation matrix, to obtain a third matrix; and a calculating unit configured to perform singular value decomposition on the third matrix, and calculate a polarization dependent loss according to a result of the singular value decomposition. According to the embodiments of this disclosure, the polarization dependent loss may be calculated more accurately.

Abstract: A bias control apparatus and method of a modulator of an optical transmitter and an optical transmitter, in which by performing mutual interference on driving signals of two Mach-Zehnder modulators constituting the modulator of the optical transmitter, output optical fields of the two Mach-Zehnder modulators are correlated. Hence, an output power signal of the modulator of the optical transmitter contains information on phase bias. Thus, the phase bias may be controlled by using the output power signal, sensitivity of the bias control may be efficiently improved, and various types of modulation formats may be applied.

Abstract: Embodiments of this disclosure provide an apparatus and method for monitoring an optical signal to noise ratio, a receiver and a communication system. The apparatus for monitoring an optical signal to noise ratio includes extracting signals from signals obtained after an equalization processing is performed on optical signals received by a receiver, the optical signals including signals of known frequencies, and the signals extracted having the same spectral characteristics as the signals of known frequencies; correcting, according to filtering parameters used in the equalization processing, the signals extracted and outputting corrected signals; and calculating an optical signal to noise ratio according to the corrected signals. According to the embodiments of this disclosure, the optical signal to noise ratio may be calculated more accurately.

Abstract: A transmission control method and apparatus for network services and controller. The transmission control method for network services includes: negotiating, before start of the network services, operational modes supported by each of links, and detecting quality of services in the operational modes supported by each of the links; grouping all network services to be transmitted according to requirements of the network services on quality of services and the quality of services in the operational modes supported by each of the links, and allocating links and operational modes for each of the groups; and designating a link for each of the network services in the groups according to the links and operational modes allocated for each of the groups. Hence, abilities of transmission quality detection and adjustment of a multi-carrier optical communication system may be used to satisfy quality requirements of different network services.

Abstract: 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.

Abstract: Embodiments of this disclosure provide a phase noise compensation apparatus and method and a receiver, in which modified signals are determined according to estimated values of an imperfection parameter of a transmitter and training sequence signals in transmission signals, and phase noises of the received signals are determined according to the modified signals, hence, an effect of the imperfection parameter of the transmitter on the phase noise is taken into account, and the phase noise may be accurately estimated, thereby performing compensation on the phase noise, and ensuring a transmission efficiency and performance of the system.

Abstract: A bit allocation method, apparatus for a multicarrier modulation signal and a system where the method includes: lowering the number of bits of a subcarrier of minimum average power in subcarriers of the multicarrier modulation signal allocated with a maximum number of bits according to a predetermined total number of bits to be adjusted including setting a total number of bits to be adjusted; determining a target number of bits according to the total number of bits; allocating a bit number for each subcarrier of the multicarrier modulation signal by using a predetermined bit allocation method according to the target; and lowering the number of bits of a subcarrier of minimum average power in the subcarriers allocated with a maximum number of bits, until a lowered total number of bits is equal to the total number of bits to be adjusted.

Abstract: Embodiments of this disclosure provide an impairment monitoring apparatus, impairment monitoring and compensating system and method. As a parameter of a impairment of a receiver end and/or a parameter of an impairment of a transmitter end is/are determined according to a preset period or a preset condition to perform compensation or calibration, complexity of calculation and power consumption of the system may be efficiently lowered. And as the parameter of the impairment of the receiver end and the parameter of the impairment of the transmitter end are not changed rapidly, determining these parameters according to the preset period or the preset condition to perform compensation or calibration will not affect an effect of the compensation or calibration, thereby ensuring a performance of the system.

Abstract: 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.