Methods and systems for reduced complexity nonlinear compensation

摘要

Aspects of the present invention provide techniques for compensating nonlinear impairments of a signal traversing an optical communications system. A parallel array of linear convolutional filters are configured to process a selected set of samples of the signal to generate an estimate of a nonlinear interference field. The predetermined set of samples comprises a first sample and a plurality of second samples. A processor applies the estimated nonlinear interference field to the first sample to least partially compensate the nonlinear impairment.

主权项

1. An apparatus for compensating a nonlinear impairment of a signal traversing an optical communications system, the apparatus comprising:
a parallel array of linear convolutional filters configured to process a selected set of samples of the signal to calculate an estimate of a nonlinear interference field, the selected set of samples comprising a first sample and a plurality of second samples; and a processor configured to apply the estimated nonlinear interference field to the first sample so as to at least partially compensate the nonlinear impairment; wherein either:
the selected set of samples of the signal are time-domain samples and each linear convolutional filter comprises a set of taps, each tap being configured to compute a product Cmn{right arrow over (A)}H(tj+m+n){right arrow over (A)}(tj+n), where Cmn is a complex number representing an efficiency of nonlinear interaction; m and n are index values that range between −M≦m≦M and −N≦n≦N; {right arrow over (A)}(t) is a vector representing the modulated time domain transmit signal; tj denotes the time of the first sample; and {right arrow over (A)}H(t) denotes the Hermitian conjugate of {right arrow over (A)}(t); orthe selected set of samples of the signal are frequency-domain samples and each linear convolutional filter comprises a set of taps, each tap being configured to compute a product {tilde over (C)}mn{right arrow over (A)}H(ωk+m+n){right arrow over (A)}(ωk+n), where {tilde over (C)}mn is a complex number representing an efficiency of nonlinear interaction; m and n are index values that range between −M≦m≦M and −N≦n≦N; {right arrow over (A)}(ω) is a vector representing the Fourier transform of the modulated transmit signal; ωk denotes the frequency of the first sample; and {right arrow over (A)}H(ω) denotes the Hermitian conjugate of {right arrow over (A)}(ω).