Ciena Corporation

Ramin Babaee

Shahab Oveis Gharan

Martin Bouchard

Kim Bryon Roberts

Aspects of the subject disclosure may include, for example, obtaining a digital input signal for conversion into analog by a digital-to-analog converter (DAC), and performing filtering operations relating to the digital input signal, wherein the filtering operations provide one or more of pre-compensation for duty-cycle distortion (DCD) associated with the DAC and pre-compensation for bit-level inter-symbol interference (ISI) associated with the DAC. Other embodiments are disclosed.

Duty-cycle distortion (DCD) and bit-level inter-symbol interference (ISI) pre- compensation for a digital-to-analog converter (DAC)

Aspects of the subject disclosure may include, for example, obtaining a data signal that includes a stream of symbols, modifying the data signal, resulting in a modified data signal, such that there is inter-symbol interference (ISI) when the modified data signal is received by a receiver, and transmitting the modified data signal over a channel to the receiver, wherein the ISI is distinct from an inverse of the channel and is introduced based on the modifying to be exploited by a decoder in the receiver for enhanced decoding. Other embodiments are disclosed.

Non-linear precoding for maximum likelihood sequence estimation (MLSE) receiver

Aspects of the subject disclosure may include, for example, identifying a modulation scheme for transmitting data from a transmitter to a receiver, identifying a plurality of symbols associated with the modulation scheme, determining that a transfer function of a filter that is applied at the transmitter imposes an interdependence amongst at least two symbols of the plurality of symbols, determining, based on the transfer function, a joint probability distribution of the plurality of symbols that reduces a signal power of at least one signal that is used to transmit the data subject to a constraint that an information rate associated with the at least one signal is greater than a threshold, and causing the data to be transmitted via the at least one signal from the transmitter to the receiver in accordance with the joint probability distribution. Other aspects are disclosed.

Apparatuses and methods for facilitating joint precoding and probabilistic constellation shaping

An apparatus comprises circuitry configured to generate a predicted error signal by applying to a digital signal a distortion model characterized by parameters configured to model circuit component mismatches in a digital-to-analog converter (DAC), circuitry configured to generate a pre-compensated digital signal using the digital signal and the predicted error signal, and circuitry configured to provide the pre-compensated digital signal to the DAC for conversion into an analog signal.

Digital-to-analog converter (DAC) distortion pre-compensation

A digital-to-analog converter (DAC) comprises circuitry configured to generate, based on a mapping, L signals representing an N-bit digital input, wherein N and L are positive integers, and wherein N&#x3c;L&#x3c;2&#x2212;1, and circuitry configured to control current flow from L weighted current sources using the L respective signals, thereby generating an analog output that uniquely represents the N-bit digital input, wherein the weighted current sources have weights configured to minimize at least one error metric associated with the analog output.

Digital-to-analog converter (DAC) architecture optimization

A receiver is configured to detect, at a communication interface, a received signal that suffers from degradations incurred over a communication channel. The receiver applies an adaptive filter to a series of received blocks of a digital representation of the received signal, thereby generating respective filtered blocks, where each received block represents 2N frequency bins, and where N is a positive integer. The receiver calculates coefficients for use by the adaptive filter on a jreceived block as a function of (i) error estimates associated with an (j&#x2212;D&#x2212;1)filtered block, where D is a positive integer representing a number of blocks, and where j is a positive integer greater than (D&#x2212;1); and (ii) an inverse of an approximate covariance matrix associated with the (j&#x2212;D&#x2212;1)received block, where the approximate covariance matrix is a diagonal matrix of size L&#xd7;L, and where L is a positive integer lower than 2N.

Approximation of recursive least squares equalization

A receiver is configured to detect, at a communication interface, a received signal that suffers from degradations incurred over a communication channel. The receiver applies an adaptive filter to a series of received blocks of a digital representation of the received signal, thereby generating respective filtered blocks. The receiver calculates coefficients for use by the adaptive filter on an jreceived block as a function of (i) error estimates associated with an (j&#x2212;D&#x2212;1)filtered block, where D is a positive integer representing a number of blocks, and where j is a positive integer greater than (D&#x2212;1); and (ii) delay compensation terms dependent on an estimate of a difference between coefficients used by the adaptive filter on an (j&#x2212;D&#x2212;1)received block and coefficients used by the adaptive filter on an (j&#x2212;1)received block

Feedback equalization with delay compensation

An optical signal modulated with a stream of symbols comprising a sequence of training symbols is received at a receiver. First equalizer circuitry calculates and applies first coefficients to digital signals representative of the optical signal, thereby resulting in first compensated signals. Second equalizer circuitry calculates second coefficients based on a correlation between the first compensated signals and digital signals representative of the sequence of training symbols and applies the second coefficients to the first compensated signals, thereby resulting in second compensated signals. Third equalizer circuitry calculates and applies third coefficients to the second compensated signals, thereby resulting in third compensated signals. The first, second, and third coefficients compensate for impairments in the optical signal varying at respective first, second, and third rates, where the third rate is higher than the first rate and lower than the second rate.

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Ottawa, Canada

Ramin Babaee