Huawei Technologies Co., Limited

Junho Chang

Zhiping Jiang

Choloong Hahn

Xuefeng Tang

A method for monitoring impairment includes: receiving a first received waveform sent by the coherent receiver; obtaining a second received waveform including a first sub-waveform and a second sub-waveform with a relative first delay therebetween according to the first received waveform; obtaining a template at a predetermined location on the fiber link according to the second received waveform, wherein the template is used for representing a nonlinear noise by a first sub-signal waveform and a second sub-signal waveform at the predetermined location that are respectively obtained from the first sub-waveform and the second sub-waveform and have the first delay therebetween; obtaining a correlation between the second received waveform and the template; changing a value of the first delay to obtain values of the correlation corresponding to different values of the first delay; and outputting a value of the first delay corresponding to a maximum value of the correlation as impairment estimation.

Method and device for monitoring impairment, coherent receiver and network apparatus

A method for monitoring generalized optical signal-to-noise ratio (gOSNR) is provided, which is applied to monitoring of an optical signal received by a coherent receiver through a fiber link. The method includes: obtaining a first received waveform; obtaining a signal part of the first received waveform; obtaining a noise part of the first received waveform according to the signal part and the first received waveform; obtaining a first correlation between the noise part and a first template at a predetermined location on the fiber link, the first correlation indicating a signal power at the predetermined location; obtaining a second correlation between the noise part and a second template at the predetermined location on the fiber link, the second correlation indicating a signal power and noise power at the predetermined location; and obtaining gOSNR at the predetermined location according to the first correlation and the second correlation.

Method and device for monitoring generalized optical signal-to-noise ratio, coherent receiver and network apparatus

The disclosed systems and methods for optical filter fault localization. The optical filter fault localization is based on: i) determining an accumulated noise density at frequencies where ASE noise is filtered out by a faulty optical filter in an optical signal; ii) comparing the accumulated noise density with predicted accumulated noise densities, the predicted accumulated noise densities representing noises predicted from a plurality of optical filters to a receiver; and iii) determining, based on the comparison of the accumulated noise density and the predicted accumulated noise densities, a location of the faulty optical filter.

Systems and methods for optical filter fault localization

The disclosed systems and methods for detecting mirror crosstalk between frequency bands equally above and below the center frequency of a Digital Subcarrier Multiplexing system include: a transmitter configured to insert zero-power symbols on half the frequency bands below center frequency, and insert other zero-power symbols, partially overlapping in time with the first zero-power symbols, on the other half of the frequency bands above center frequency. A receiver zeroes out ASE and other noises during the overlapping portion of all the zero-power symbols, then uses the power detected during the remaining portion of each zero-power symbol in each frequency band to accurately evaluate the mirror crosstalk from the corresponding frequency band on the opposite side of center frequency.

Transmitter and receiver for mirror crosstalk evaluation and methods therefor

Optical transmitters, receivers, and methods are described in an optical network. An optical transmitter comprises an encoder configured to receive an input data stream and to encode the input data stream into a signal. The signal is defined as a sequence of regular units, and a rotator is configured to receive each unit of the signal and to output, for each given input unit with an input state of polarization (SOP), a respective given output unit associated with an output SOP. The output SOP of the given output unit is different from a corresponding output SOP of each other output unit that is immediately adjacent to the given output unit. The output SOPs of the units in a transmitted signal may form an alternating pattern (or other repeating pattern), which may help to lower the average BER, in particular, due to forward error correction (FEC).

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Kanata, Canada

Junho Chang