Abstract: A controlled switch having N inputs and a single output (N?2) is switchable between N states. In each state a respective one of the inputs is connected to the single output. There are N sources of sub-streams of analog samples, each sub-stream composed of pairs of adjacent analog samples. Each source is coupled to a respective one of the inputs. In operation, the controlled switch is controlled by a control signal to switch between the N states. While the controlled switch is in any one of the states, a data transition occurs between two adjacent analog samples in the sub-stream whose source is coupled to the input that is connected to the single output. The single output yields the high-bandwidth analog signal. Any pair of adjacent analog samples in any one of the sub-streams substantially determines a corresponding pair of adjacent analog samples in the high-bandwidth analog signal.

Abstract: In data communications, a suitably designed contrast coding scheme, comprising a process of contrast encoding at a transmitter end and a process of contrast decoding at a receiver end, may be used to adjust the contrast in bit error rate (BER) experienced by different classes of bits. Contrast coding may be used to tune the BERs experienced by different subsets of bits, relative to each other, to better match a plurality of forward error correction (FEC) schemes used for transmission of information bits, which may ultimately provide a communications system having a higher noise tolerance, or greater data capacity, or smaller size, or lower heat.

Abstract: Client data bits, including first client data bits and second client data bits, are communicated from a transmitter to a receiver. At the transmitter, the first client data bits are processed to generate processed values, where each processed value is more likely to be a first element than a second element. Forward Error Correction ‘FEC’ encoding is applied to the second client data bits to generate FEC-encoded values. Symbols are created by mapping the FEC-encoded values to first positions in the symbols and by mapping the processed values to second positions in the symbols. The symbols are modulated onto a communications channel using a modulation scheme with a code that assigns a lower average energy to symbols containing the first elements in the second positions than to symbols containing the second elements in the second positions. At the receiver, client data bits are decoded using conditional chain decoding.

Abstract: A super-frame for transmission in an optical communications system comprises two or more data frames and a parity frame. All frames in the super-frame have been encoded in accordance with a first Forward Error Correction (FEC) scheme. The parity frame is computed over the two or more data frames (prior to or concurrently with or after encoding via the first FEC scheme) according to a second FEC scheme. At a receiver, the super-frame is decoded in accordance with the first FEC scheme to generate a set of FEC decoded frames in which residual errors are clustered, that is, are non-Poisson. The second FEC scheme, which is particularly suited or designed to correct the clustered non-Poisson residual errors, is used to correct the residual errors.

Abstract: Generation of data streams for two dimensions comprises compensation for a nonideal response of a signal path in an optical communications signal. The data streams are converted to analog electrical signals which drive two dimensions of an electrical-to-optical converter. Output of the electrical-to-optical converter is coupled through an optical link to an optical-to-electrical converter.

Abstract: A processor of an apparatus is configured to apply one or more control algorithms using estimated data to adjust the one or more control parameters of a section of an optical fiber network. The estimated data are derived from measurements of optical signals in the section and from knowledge of the section. The estimated data is a function of optical nonlinearity and of amplified spontaneous emission.

Abstract: Compression coding techniques are proposed for use with forward error correction (FEC) coding, which may provide higher information rates by reducing the proportion of redundant bits relative to information bits that are transmitted from a transmitter to a receiver. In one example, the transmitter calculates a plurality of determiners from a set of information bits, where each determiner is calculated as a first function of a respective first subset of the information bits. The transmitter then calculates a nub as a second function of the plurality of determiners, where the nub comprises a number of redundant bits that is less than a number of bits comprised in the plurality of determiners. The set of information bits is transmitted to the receiver in a first manner, and the nub is transmitted to the receiver in a second manner, where the first manner may be distinct from the second manner.

Abstract: In a communications system having an analog channel configured to convey a data signal from a transmitter to a receiver, a method of mitigating narrow-band impairment imposed by the analog channel on the data signal within a bounded spectral region of a spectrum of the data signal. A transmitter digital signal processor (Tx DSP) applying a first adaptation function to the data signal prior to transmitting the data signal through the analog channel. A receiver digital signal processor (Rx DSP) applying a second adaptation function to the data signal received through the analog channel. The first and second adaptation functions are selected to cooperatively mitigate effects of the narrow-band impairment imposed by the analog channel.

Abstract: In data communications, a suitably designed contrast coding scheme, comprising a process of contrast encoding at a transmitter end and a process of contrast decoding at a receiver end, may be used to adjust the contrast in bit error rate (BER) experienced by different classes of bits. Contrast coding may be used to tune the BERs experienced by different subsets of bits, relative to each other, to better match a plurality of forward error correction (FEC) schemes used for transmission of information bits, which may ultimately provide a communications system having a higher noise tolerance, or greater data capacity, or smaller size, or lower heat.

Abstract: A super-frame for transmission in an optical communications system comprises two or more data frames and a parity frame. All frames in the super-frame have been encoded in accordance with a first Forward Error Correction (FEC) scheme. The parity frame is computed over the two or more data frames (prior to or concurrently with or after encoding via the first FEC scheme) according to a second FEC scheme. At a receiver, the super-frame is decoded in accordance with the first FEC scheme to generate a set of FEC decoded frames in which residual errors are clustered, that is, are non-Poisson. The second FEC scheme, which is particularly suited or designed to correct the clustered non-Poisson residual errors, is used to correct the residual errors.

Abstract: A compensation function mitigates a substantial portion of the dispersion imparted to a communications signal by an optical communications system. A digital input signal is digitally processed using the compensation function to generate a predistorted signal. An amplitude and a phase of an optical signal are modulated using a pair of orthogonal signal components to generate a predistorted optical signal for transmission. In one implementation, the pair of orthogonal signal components are components of the predistorted signal. In another implementation, the predistorted signal is processed using a non-linear compensator to generate a further distorted signal and the pair of orthogonal signal components are components of the further distorted signal. In that implementation, the non-linear compensator is configured to substantially compensate for nonlinearities in one or both of an optical modulator of a transmitter of the system and an optical-to-electrical converter of a receiver of the system.

Abstract: A computer-implemented method to increase capacity of an optical network based on overall excess margin in the optical network includes determining an objective function based on data associated with a plurality of optical signals in the optical network, each of the optical signals between modems in the optical network, wherein an input to the objective function comprises how much margin the optical signals have until Forward Error Correction (FEC) limits are reached; performing an optimization of the objective function based on changing a plurality of parameters of the optical signals; and causing changes to settings of a subset of the modems based on the performing to change the capacity of the optical network.

Abstract: A high speed signal generator comprises a digital signal processing (DSP) block configured to process an input digital signal to generate in parallel a first digital sub-band signal having frequency components within a first spectral range and a second digital sub-band signal having frequency components within the first spectral range. A first Digital-to-Analog Converter (DAC) is configured to process the first digital sub-band signal to generate a first analog sub-band signal and a second DAC is configured to process the second digital sub-band signal to generate a second analog sub-band signal. A combiner is to combine the first analog sub-band signal and the second analog sub-band signal to generate an output analog signal having frequency components covering a substantially continuous spectral range from a lower frequency f1 to a higher frequency f2.

Abstract: Multiple receivers are comprised in a flexible coherent transceiver of a multi-span optical fiber network. Each of the multiple receivers is operative to handle communications on a respective channel. The multiple receivers measure optical characteristics. For each of the multiple receivers, the optical characteristics include optical nonlinear interactions on the respective channel, the optical nonlinear interactions being at least partially dependent from one span to another span. An optical power of a signal on each of the multiple channels is adjusted as a function of the optical characteristics.

Abstract: Adjustment of one or more control parameters of a section of an optical fiber network involves taking measurements of optical signals in the section, deriving estimated data from the measurements and from knowledge of the section, where the estimated data is a function of optical nonlinearity and of amplified spontaneous emission, and applying one or more control algorithms using the estimated data to adjust the one or more control parameters.

Abstract: A processor of an apparatus is configured to apply one or more control algorithms using estimated data to adjust the one or more control parameters of a section of an optical fiber network. The estimated data are derived from measurements of optical signals in the section and from knowledge of the section. The estimated data is a function of optical nonlinearity and of amplified spontaneous emission.

Abstract: Adjustment of one or more control parameters of a section of an optical fiber network involves taking measurements of optical signals in the section, deriving estimated data from the measurements and from knowledge of the section, where the estimated data is a function of optical nonlinearity and of amplified spontaneous emission, and applying one or more control algorithms using the estimated data to adjust the one or more control parameters.

Abstract: A digital instruction is generated regarding one or more electrical-to-optical conversion impairments induced at the transmitter of an optical communication system. The digital instruction may be used by the transmitter to reduce the impairments.

Abstract: A compensation function mitigates a substantial portion of the dispersion imparted to a communications signal by an optical communications system. A digital input signal is digitally processed using the compensation function to generate a predistorted signal. An amplitude and a phase of an optical signal are modulated using a pair of orthogonal signal components to generate a predistorted optical signal for transmission. In one implementation, the pair of orthogonal signal components are components of the predistorted signal. In another implementation, the predistorted signal is processed using a non-linear compensator to generate a further distorted signal and the pair of orthogonal signal components are components of the further distorted signal. In that implementation, the non-linear compensator is configured to substantially compensate for nonlinearities in one or both of an optical modulator of a transmitter of the system and an optical-to-electrical converter of a receiver of the system.

Abstract: A transmitter comprises a complex mixer to generate a single I analog drive signal and a single Q analog drive signal, and a single multi-dimensional optical modulator configured to modulate an optical carrier light using the single I analog drive signal and the single Q analog drive signal to produce a modulated optical signal for transmission. Alternatively, a transmitter comprises a complex mixer to generate two I analog drive signals and two Q analog drive signals, and a single multi-dimensional multiple-electrode optical modulator configured to modulate an optical carrier light using the analog drive signals to produce a modulated optical signal for transmission. In both transmitters, the optical carrier light is produced by a single laser, and frequency components of the first data signal are located in a different portion of a spectrum of the modulated optical signal than frequency components of the second data signal.