Abstract: A method and an apparatus for evaluating transmission impairments of a multiplexing converter. According to the method, impairments of a multiplexing converter are equivalent to the equivalent multiplicative noise and the equivalent additive noise, so as to allow evaluation of transmission impairments of the multiplexing converter, thereby to allow evaluation of the performance of a communication system. The multiplexing converter is a multiplexing analog-to-digital converter, or a multiplexing digital-to-analog converter. According to the present application, impairments of a multiplexing converter can be evaluated accurately, the performance evaluation of a communication system using the multiplexing converter is given, without being affected by an amplitude, a modulation format and a transmission rate of an input signal.

Abstract: The present disclosure provides an apparatus and method for measuring a nonlinear signal-to-noise ratio, and a test instrument. The method for measuring a nonlinear signal-to-noise ratio may include performing notch operation on at least one frequency point in a spectrum of an input signal in a symbol domain or a bit domain; performing spectrum measurement on an output signal after passing through a nonlinear system; and estimating a nonlinear signal-to-noise ratio of at least one frequency point of the nonlinear system according to a spectrum of the output signal. According to the embodiments of the present disclosure, when the notch operation is performed, internal structures of symbols or bits of the input signal may be retained, and an accuracy of the measurement of the nonlinear signal-to-noise ratio may be improved.

Abstract: A method, an apparatus and a system to measure nonlinear correlation parameters of a nonlinear device, a processor to, perform band-stop filtering on a signal to be measured to generate a notch signal, and calculate a first nonlinear correlation parameter of the nonlinear device when the signal to be measured is transmitted according to a first output signal of the nonlinear device after the notch signal is input into the nonlinear device; calculate gain compression correction coefficients according to a second output signal of the nonlinear device after the first input signal is input into the nonlinear. The first input signal and the signal to be measured may have identical power and different signal probability distribution. The processor is to correct the first nonlinear correlation parameter according to the gain compression correction coefficients to obtain a second nonlinear correlation parameter of the nonlinear device when the signal to be measured is transmitted.

Abstract: A performance estimation apparatus and method for a nonlinear communication system and an electronic device. The nonlinear communication system is equated with by an equivalent model including an equivalent linear model and an equivalent additive noise model, and the equivalent additive noise outputted by the equivalent additive noise model is mathematically uncorrelated to the signal inputted into the equivalent model. Performances of the nonlinear communication system of different modulation formats at different baud rates may be accurately estimated.

Abstract: The present disclosure provides an apparatus and method for measuring a nonlinear signal-to-noise ratio, and a test instrument. The method for measuring a nonlinear signal-to-noise ratio may include performing notch operation on at least one frequency point in a spectrum of an input signal in a symbol domain or a bit domain; performing spectrum measurement on an output signal after passing through a nonlinear system; and estimating a nonlinear signal-to-noise ratio of at least one frequency point of the nonlinear system according to a spectrum of the output signal. According to the embodiments of the present disclosure, when the notch operation is performed, internal structures of symbols or bits of the input signal may be retained, and an accuracy of the measurement of the nonlinear signal-to-noise ratio may be improved.

Abstract: A method and apparatus for generating a signal. The method includes: by taking a reference signal as a standard, cyclically performing isoprobabilistic processing and isospectral processing, or cyclically perform isoprobabilistic processing, perturbation processing and isospectral processing, on an input signal, until an obtained signal satisfies both a requirement on a target probability distribution and a requirement on a target spectrum, where a probability distribution of the reference signal satisfying the requirement on a target probability distribution, the isoprobabilistic processing referring to processing that makes the probability distribution of an output signal identical to the probability distribution of the reference signal. Therefore, a signal that satisfies both the requirement on the specific probability distribution and the requirement on the spectrum can be generated, and the degree of compliance is higher.

Abstract: This disclosure provides a signal generation device and an equalization processing device. The signal generation device generates a pilot sequence and payload, the pilot sequence and the payload having identical or similar amplitude probability characteristics. Hence, nonlinear interference may be resisted, and performance of the communication system may be improved.

Abstract: A performance estimation apparatus and method for a nonlinear communication system and an electronic device. The nonlinear communication system is equated with by an equivalent model including an equivalent linear model and an equivalent additive noise model, and the equivalent additive noise outputted by the equivalent additive noise model is mathematically uncorrelated to the signal inputted into the equivalent model. Performances of the nonlinear communication system of different modulation formats at different baud rates may be accurately estimated.

Abstract: A method and apparatus for monitoring the change of state of polarization and a receiver. The method for monitoring the change of state of polarization includes: extracting a matrix of equalization filter tap coefficients of a receiver; performing an FFT operation of N taps on each path of equalization filter tap coefficients of the matrix to obtain a converted matrix, a sum of each path of equalization filter tap coefficients of the converted matrix being a value of non-zero frequency; and estimating an amount of change of state of polarization by using at least one path of equalization filter tap coefficients of the converted matrix. Thus, as the sum of the tap coefficients is shifted in the frequency domain from the zero frequency to a higher frequency (non-zero frequency), an effect of imperfection of the transmitter on a monitoring result of the change of state of polarization may be avoided.

Abstract: An inter-channel linear crosstalk estimation method and apparatus and a communication system are disclosed.

Abstract: A method and apparatus for monitoring the change of state of polarization and a receiver. The method for monitoring the change of state of polarization includes: extracting a matrix of equalization filter tap coefficients of a receiver; performing an FFT operation of N taps on each path of equalization filter tap coefficients of the matrix to obtain a converted matrix, a sum of each path of equalization filter tap coefficients of the converted matrix being a value of non-zero frequency; and estimating an amount of change of state of polarization by using at least one path of equalization filter tap coefficients of the converted matrix. Thus, as the sum of the tap coefficients is shifted in the frequency domain from the zero frequency to a higher frequency (non-zero frequency), an effect of imperfection of the transmitter on a monitoring result of the change of state of polarization may be avoided.

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: 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: 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: 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 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.

Abstract: An inter-channel linear crosstalk estimation method and apparatus and a communication system are disclosed.

Abstract: 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.