Abstract: A coherent optical receiver includes equalizer circuitry having a plurality of taps, the equalizer circuitry being configured to receive an input signal and compensate for polarization mode dispersion affecting the input signal to generate a compensated input signal. The coherent optical receiver further includes error evaluation circuitry configured to calculate a determinant of a frequency-domain (FD) coefficient-based matrix using a plurality of tap signals from among the plurality of taps, adjust an error of convergence of the compensated input signal to generate an adjusted input signal, and iteratively adjust the determinant of the FD coefficient-based matrix based on the adjusted input signal to minimize the error of convergence.

Abstract: A decoder circuit includes first and second decoders. The first decoder is a first type of decoder configured to receive data encoded with an error correction code and decode and eliminate errors from a first subset of codewords of the data. The second decoder is a second type of decoder configured receive the data encoded with the error correction code and decode and eliminate errors from a second subset of codewords of the data, different from the first subset of the codewords, without attempting to decode and eliminate errors from the first subset of the codewords.

Abstract: A decoder for a receiver in a communication system includes an interface configured to receive encoded input data via a communication channel. The encoded input data includes forward error correction (FEC) codewords. A processor is configured to decode the FEC codewords using low density parity check (LDPC) codes defined by a parity check matrix. The parity check matrix is defined by both regular column partition (RCP) constraints and quasi-cyclic (QC) constraints. An output circuit is configured to output a decoded codeword based on the FEC codewords decoded by the processor.

Abstract: A coherent optical receiver includes equalizer circuitry having a plurality of taps, the equalizer circuitry being configured to receive an input signal and compensate for polarization mode dispersion affecting the input signal to generate a compensated input signal. The coherent optical receiver further includes error evaluation circuitry configured to calculate a determinant of a frequency-domain (FD) coefficient-based matrix using a plurality of tap signals from among the plurality of taps, adjust an error of convergence of the compensated input signal to generate an adjusted input signal, and iteratively adjust the determinant of the FD coefficient-based matrix based on the adjusted input signal to minimize the error of convergence.

Abstract: A decoder circuit includes first and second decoders. The first decoder is a first type of decoder configured to receive data encoded with an error correction code and decode and eliminate errors from a first subset of codewords of the data. The second decoder is a second type of decoder configured receive the data encoded with the error correction code and decode and eliminate errors from a second subset of codewords of the data, different from the first subset of the codewords, without attempting to decode and eliminate errors from the first subset of the codewords.

Abstract: A method and structure for tap centering in a coherent optical receiver device. The center of gravity (CG) of the filter coefficients can be used to evaluate a proper convergence of a time-domain adaptive equalizer. However, the computation of CG in a dual-polarization optical coherent receiver is difficult when a frequency domain (FD) adaptive equalizer is adopted. In this case, the implementation of several inverse fast-Fourier transform (IFFT) stages is required to back time domain impulse response. Here, examples of the present invention estimate CG directly from the FD equalizer taps and compensate for an error of convergence based off of the estimated CG. This estimation method and associated device architecture is able to achieve an excellent tradeoff between accuracy and complexity.

Abstract: A method and device for energy-efficient decoders. The decoder device can include a plurality of decoder modules configured to process an input data signal having a plurality of forward error correction (FEC) codewords. This plurality of decoder modules can include at least a first decoder followed by a second decoder. The first decoder can be low-power to first eliminate most of the errors of the codewords and the second decoder can be high-performance to correct the remaining errors. Alternatively, the first decoder can be high-performance to correct the codewords until the low-power decoder can correct the remaining errors. A classifier module can be included to determine portions of the codewords to be directed to any one of the plurality of decoder modules. These implementations can be extended to use additional decoders with different decoding algorithms and optimized to maximize decoder performance given a maximum power constraint.

Abstract: A method and structure for a coherent optical receiver device. Timing recovery (TR) is implemented after channel dispersion (i.e., chromatic dispersion (CD) and polarization mode dispersion (PMD)) compensation blocks. This architecture provides both improves performance and reduces power consumption of the device. Also, a TR loop is provided, enabling computing, by an error evaluation module, a first sampling phase error (SPE) and computing, by a timing phase information (TPI) module coupled to the error evaluation module, a second SPE from a plurality of CD equalizer taps PMD equalizer taps. The first and second SPE are combined into a total phase error (TPE) in a combining module, and the resulting TPE is filtered by a timing recovery (TR) filter coupled to an interpolated timing recovery (ITR) module and the combining module. The ITR module then synchronizes an input signal of the coherent optical receiver according to the TPE.

Abstract: A decoder for a receiver in a communication system includes an interface configured to receive encoded input data via a communication channel. The encoded input data includes forward error correction (FEC) codewords. A processor is configured to decode the FEC codewords using low density parity check (LDPC) codes defined by a parity check matrix. The parity check matrix is defined by both regular column partition (RCP) constraints and quasi-cyclic (QC) constraints. An output circuit is configured to output a decoded codeword based on the FEC codewords decoded by the processor.

Abstract: A method and structure for tap centering in a coherent optical receiver device. The center of gravity (CG) of the filter coefficients can be used to evaluate a proper convergence of a time-domain adaptive equalizer. However, the computation of CG in a dual-polarization optical coherent receiver is difficult when a frequency domain (FD) adaptive equalizer is adopted. In this case, the implementation of several inverse fast-Fourier transform (IFFT) stages is required to back time domain impulse response. Here, examples of the present invention estimate CG directly from the FD equalizer taps and compensate for an error of convergence based off of the estimated CG. This estimation method and associated device architecture is able to achieve an excellent tradeoff between accuracy and complexity.

Abstract: A method and structure for a coherent optical receiver device. Timing recovery (TR) is implemented after channel dispersion (i.e., chromatic dispersion (CD) and polarization mode dispersion (PMD)) compensation blocks. This architecture provides both improves performance and reduces power consumption of the device. Also, a TR loop is provided, enabling computing, by an error evaluation module, a first sampling phase error (SPE) and computing, by a timing phase information (TPI) module coupled to the error evaluation module, a second SPE from a plurality of CD equalizer taps PMD equalizer taps. The first and second SPE are combined into a total phase error (TPE) in a combining module, and the resulting TPE is filtered by a timing recovery (TR) filter coupled to an interpolated timing recovery (ITR) module and the combining module. The ITR module then synchronizes an input signal of the coherent optical receiver according to the TPE.

Abstract: A method and structure for a coherent optical receiver device. Timing recovery (TR) is implemented after channel dispersion (i.e., chromatic dispersion (CD) and polarization mode dispersion (PMD)) compensation blocks. This architecture provides both improves performance and reduces power consumption of the device. Also, a TR loop is provided, enabling computing, by an error evaluation module, a first sampling phase error (SPE) and computing, by a timing phase information (TPI) module coupled to the error evaluation module, a second SPE from a plurality of CD equalizer taps PMD equalizer taps. The first and second SPE are combined into a total phase error (TPE) in a combining module, and the resulting TPE is filtered by a timing recovery (TR) filter coupled to an interpolated timing recovery (ITR) module and the combining module. The ITR module then synchronizes an input signal of the coherent optical receiver according to the TPE.

Abstract: A method and structure for tap centering in a coherent optical receiver device. The center of gravity (CG) of the filter coefficients can be used to evaluate a proper convergence of a time-domain adaptive equalizer. However, the computation of CG in a dual-polarization optical coherent receiver is difficult when a frequency domain (FD) adaptive equalizer is adopted. In this case, the implementation of several inverse fast-Fourier transform (IFFT) stages is required to back time domain impulse response. Here, examples of the present invention estimate CG directly from the FD equalizer taps and compensate for an error of convergence based off of the estimated CG. This estimation method and associated device architecture is able to achieve an excellent tradeoff between accuracy and complexity.

Abstract: A method and structure for equalization in coherent optical receivers. Block-based LMS (BLMS) algorithm is one of the many efficient adaptive equalization algorithms used to (i) increase convergence speed and (ii) reduce implementation complexity. Since the computation of the equalizer output and the gradient of the error are obtained using a linear convolution, BLMS can be efficiently implemented in the frequency domain with the constrained frequency-domain BLMS (FBLMS) adaptive algorithm. The present invention introduces a novel reduced complexity constrained FBLMS algorithm. This new approach replaces the two discrete Fourier transform (DFT) stages required to evaluate the DFT of the gradient error, by a simple frequency domain filtering. Implementation complexity can be drastically reduced in comparison to the standard constrained FBLMS. Furthermore, the new approach achieves better performance than that obtained with the unconstrained FBLMS in ultra-high speed coherent optical receivers.

Abstract: A method and structure for tap centering in a coherent optical receiver device. The center of gravity (CG) of the filter coefficients can be used to evaluate a proper convergence of a time-domain adaptive equalizer. However, the computation of CG in a dual-polarization optical coherent receiver is difficult when a frequency domain (FD) adaptive equalizer is adopted. In this case, the implementation of several inverse fast-Fourier transform (IFFT) stages is required to back time domain impulse response. Here, examples of the present invention estimate CG directly from the FD equalizer taps and compensate for an error of convergence based off of the estimated CG. This estimation method and associated device architecture is able to achieve an excellent tradeoff between accuracy and complexity.

Abstract: A method and structure for a coherent optical receiver device. Timing recovery (TR) is implemented after channel dispersion (i.e., chromatic dispersion (CD) and polarization mode dispersion (PMD)) compensation blocks. This architecture provides both improves performance and reduces power consumption of the device. Also, a TR loop is provided, enabling computing, by an error evaluation module, a first sampling phase error (SPE) and computing, by a timing phase information (TPI) module coupled to the error evaluation module, a second SPE from a plurality of CD equalizer taps PMD equalizer taps. The first and second SPE are combined into a total phase error (TPE) in a combining module, and the resulting TPE is filtered by a timing recovery (TR) filter coupled to an interpolated timing recovery (ITR) module and the combining module. The ITR module then synchronizes an input signal of the coherent optical receiver according to the TPE.

Abstract: A method and structure for tap centering in a coherent optical receiver device. The center of gravity (CG) of the filter coefficients can be used to evaluate a proper convergence of a time-domain adaptive equalizer. However, the computation of CG in a dual-polarization optical coherent receiver is difficult when a frequency domain (FD) adaptive equalizer is adopted. In this case, the implementation of several inverse fast-Fourier transform (IFFT) stages is required to back time domain impulse response. Here, examples of the present invention estimate CG directly from the FD equalizer taps and compensate for an error of convergence based off of the estimated CG. This estimation method and associated device architecture is able to achieve an excellent tradeoff between accuracy and complexity.

Abstract: A method and structure for a coherent optical receiver device. Timing recovery (TR) is implemented after channel dispersion (i.e., chromatic dispersion (CD) and polarization mode dispersion (PMD)) compensation blocks. This architecture provides both improves performance and reduces power consumption of the device. Also, a TR loop is provided, enabling computing, by an error evaluation module, a first sampling phase error (SPE) and computing, by a timing phase information (TPI) module coupled to the error evaluation module, a second SPE from a plurality of CD equalizer taps PMD equalizer taps. The first and second SPE are combined into a total phase error (TPE) in a combining module, and the resulting TPE is filtered by a timing recovery (TR) filter coupled to an interpolated timing recovery (ITR) module and the combining module. The ITR module then synchronizes an input signal of the coherent optical receiver according to the TPE.

Abstract: A method and structure for equalization in coherent optical receivers. Block-based LMS (BLMS) algorithm is one of the many efficient adaptive equalization algorithms used to (i) increase convergence speed and (ii) reduce implementation complexity. Since the computation of the equalizer output and the gradient of the error are obtained using a linear convolution, BLMS can be efficiently implemented in the frequency domain with the constrained frequency-domain BLMS (FBLMS) adaptive algorithm. The present invention introduces a novel reduced complexity constrained FBLMS algorithm. This new approach replaces the two discrete Fourier transform (DFT) stages required to evaluate the DFT of the gradient error, by a simple frequency domain filtering. Implementation complexity can be drastically reduced in comparison to the standard constrained FBLMS. Furthermore, the new approach achieves better performance than that obtained with the unconstrained FBLMS in ultra-high speed coherent optical receivers.

Abstract: A method and structure for equalization in coherent optical receivers. Block-based LMS (BLMS) algorithm is one of the many efficient adaptive equalization algorithms used to (i) increase convergence speed and (ii) reduce implementation complexity. Since the computation of the equalizer output and the gradient of the error are obtained using a linear convolution, BLMS can be efficiently implemented in the frequency domain with the constrained frequency-domain BLMS (FBLMS) adaptive algorithm. The present invention introduces a novel reduced complexity constrained FBLMS algorithm. This new approach replaces the two discrete Fourier transform (DFT) stages required to evaluate the DFT of the gradient error, by a simple frequency domain filtering. Implementation complexity can be drastically reduced in comparison to the standard constrained FBLMS. Furthermore, the new approach achieves better performance than that obtained with the unconstrained FBLMS in ultra-high speed coherent optical receivers.