Abstract: Methods and systems are provided for timing synchronization for reception of highly-spectrally efficient communications. An example method may include, filtering, in a receiver, a received inter-symbol correlated (ISC) signal to generate a filtered ISC signal. The method may further include locking to a timing pilot signal of the filtered ISC signal. The timing pilot signal may include a sub-harmonic frequency of a clock signal associated with the received ISC signal. A timing pilot estimate signal of the timing pilot signal may be generated. The timing pilot estimate signal may be cancelled from the filtered partial response signal to generate an output ISC signal. The timing pilot signal includes a signal at ±(1/n*Fbaud), where n is an integer greater than 2, and Fbaud is a symbol rate of the clock signal. The clock signal may be recovered from the filtered ISC signal.

Abstract: One or more embodiments describe a decision feedback equalizer for highly spectrally efficient communications. A method may be performed in a decision feedback equalizer (DFE). The method may include initializing values of tap coefficients of the DFE based on values of tap coefficients of a partial response filter through which said transmitted symbols passed en route to said sequence estimation circuit. The method may include receiving estimates of transmitted symbols from a sequence estimation circuit, and receiving an error signal that is generated based on an estimated partial response signal output by the sequence estimation circuit. The method may include updating values of tap coefficients of the DFE based on the error signal and the estimates of transmitted symbols. The method may include generating one or more constraints that restrict the impact of the error signal on the updating of the values of the tap coefficients of the DFE.

Abstract: A method and system for configuring one or both of a transmitter pulse-shaping filter and a receiver pulse-shaping filter to generate a total partial response that incorporates a predetermined amount of inter-symbol interference (ISI), based on one or more defined performance-related variables and one or more set constraints that are applicable to one or both of the transmitter pulse-shaping filter and the receiver pulse-shaping filters. The predetermined amount of ISI is determined based on an estimation process during extraction of data from an output of the receiver pulse-shaping filter, such that performance of total partial response based communication matches or surpasses performance of communication incorporating filtering based on no or near-zero ISI. The configuring may comprise determining optimized filtering configuration, by applying an optimization process which is based on, at least in part, the one or more constraints and the one or more performance-related variables.

Abstract: One or more embodiments describe a decision feedback equalizer with multiple cores for highly spectrally efficient communications. An equalization circuit in a receiver may include a decision feedback equalizer circuit having a first plurality of tap coefficients that are determined based on a cost function that receives as input an error signal that is an inter-symbol-correlated (ISC) signal. The decision feedback equalizer circuit may further include a second plurality of tap coefficients that are determined based on a filter with an ISC response. The cost function may determine the mean square of the error signal. The cost function is constrained or unconstrained. The error signal may represents error caused by a channel. In some embodiments, the ISC signal may be a partial response signal, and the filter with an ISC response may be a partial response filter.

Abstract: A receiver may process a received signal to generate a processed received signal. The receiver may generate, during a sequence estimation process, an estimate of a phase error of the processed received signal. The receiver may generate an estimate of a value of a transmitted symbol corresponding to the received signal based on the estimated phase error. The generation of the estimate of the phase error may comprise generation of one or more phase candidate vectors. The generation of the estimate may comprise calculation of a metric based on the one or more phase candidate vectors. The calculation of the metric may comprise phase shifting the processed received signal based on the estimated phase error resulting in a phase-corrected received signal. The calculation of the metric may comprise calculating a Euclidean distance based on the phase-corrected received signal and one or more symbol candidate vectors.

Abstract: One or more embodiments describe a decision feedback equalizer utilizing symbol error rate biased adaptation function for highly spectrally efficient communications. A method may be performed in a decision feedback equalizer (DFE). The method may include determining values of tap coefficients used by the DFE based. The tap coefficients may be determined based on an error signal that is based on an estimated inter-symbol-correlated (ISC) signal. The tap coefficients may be determined based on a set of error vector(s), where each error vector in the set represents a difference between estimated symbols generated in the receiver and expected symbols. Determining the values of the tap coefficients may include using a symbol error rate function that estimates the actual symbol error rate in the receiver, wherein the symbol error rate function receives as input the set of error vector(s).

Abstract: A receiver is configured to receive a sample of an inter-symbol correlated (ISC) signal, the sample corresponding to a time instant when phase and/or amplitude of the ISC signal is a result of correlation among a plurality of symbols of a transmitted symbol sequence. The receiver may linearize the sample of the ISC signal. The receiver may calculate a residual signal value based on the linearized sample of the ISC signal. The receiver may generate an estimate of one or more of said plurality of symbols based on a slicing of the residual signal value. The linearization may comprise applying an estimate of an inverse of a non-linear model. The non-linear model may be a model of nonlinearity experienced by the ISC signal in a transmitter from which the ISC signal originated, in a channel through which the ISC signal passed en route to the receiver, and/or in a front-end of the receiver.

Abstract: A receiver comprises a sequence estimation circuit and a soft-input-soft-output (SISO) decoder. The sequence estimation circuit comprises circuitry operable to generate first soft bit decisions for symbols of a received inter-symbol-correlated signal. The SISO decoder comprises circuitry operable to decode the first soft bit decisions to generate corrected soft bit decisions. The circuitry of the sequence estimation circuit is operable to generate, based on the corrected soft bit decisions, second soft bit decisions for the symbols of the received inter-symbol-correlated signal, which are improved/refined relative to the first soft bit decisions.

Abstract: A transmitter inserts parity samples into a stream of information symbols in an inter-symbol correlated (ISC) signal. The inserted parity samples may be utilized to generate estimates of corresponding information symbols when they are received by a receiver. The information symbols may be pulse shaped by a first pulse shaping filter characterized by a first response. The parity samples may be pulsed shaped by a second pulse shaping filter characterized by a second response. The first response and the second response are diverse or uncorrelated. The transmitter may transmit the ISC signal comprising the pulse shaped information symbols and the pulse shaped parity samples. The parity samples may be generated utilizing a non-linear function over a plurality of the information symbols. The non-linear function may be diverse from a partial response signal convolution corresponding to the information symbols and is designed according to a desired SNR value at the receiver.

Abstract: A transmitter may comprise a symbol mapper circuit and operate in at least two modes. In a first mode, the number of symbols output by the mapper circuit per orthogonal frequency division multiplexing (OFDM) symbol transmitted by said transmitter may be greater than the number of data-carrying subcarriers used to transmit the OFDM symbol. In a second mode, the number of symbols output by said mapper circuit per orthogonal frequency division multiplexing (OFDM) symbol transmitted by said transmitter is less than or equal to the number of data-carrying subcarriers used to transmit said OFDM symbol. The symbols output by the symbol mapper circuit may be N-QAM symbols. While the circuitry operates in the first mode, the symbols output by the mapper may be converted to physical subcarrier values via filtering and decimation prior to being input to an IFFT circuit.

Abstract: A method and system for dynamic configuring of one or both of a transmitter pulse-shaping filter and a receiver pulse-shaping filter to generate a total partial response that incorporates a predetermined amount of inter-symbol interference (ISI). The predetermined amount of ISI is determined based on an estimation process during extraction of data from an output of the receiver pulse-shaping filter, such that performance of total partial-response-based communication matches or surpasses performance of communication incorporating filtering based on no or near-zero ISI. The reconfiguring may comprise obtaining data relating to changes affecting one or more of: the pulse-shaping filtering, and a channel and/or an interface used in the communication of data based on the total partial response, and adjusting the filter configuration, such as by determining a new optimized filtering configuration or changes to existing configurations (e.g., by applying a filtering optimization process).

Abstract: A receiver may be dynamically configurable, during run-time, into a plurality of modes of operation. In a first mode of operation the receiver may demodulate received signals having relative low inter-symbol correlation using a near zero ISI filter and symbol slicing. In a second mode of operation the receiver may demodulate received signals having relatively high inter-symbol correlation using an input filter configured to achieve a desired total partial response and a sequence estimation algorithm.

Abstract: In accordance with an example implementation of this disclosure, a receiver may comprise a signal reconstruction circuit and a nonlinearity modeling circuit. The nonlinearity modeling circuit may be operable to generate a look-up table (LUT)-based model of nonlinear distortion present in a received signal. An entry of the LUT may comprise a signal power parameter value and a distortion parameter value. The signal reconstruction circuit may be operable to generate one or more candidates for a transmitted signal corresponding to the received signal. The signal reconstruction circuit may be operable to distort the one or more candidates according to the model, the distortion resulting in one or more reconstructed signals. The signal reconstruction circuit may be operable to decide a best one of the candidates based on the one or more reconstructed signals.

Abstract: A receiver may receive a signal that was generated by passage of symbols through a non-linear circuit. An equalizer of the receiver may equalize the received signal based on a first non-linearity compensated, inter-symbol correlated (ISC) feedback signal to generate an equalized signal. The receiver may correct a phase error of the equalized signal to generate a phase-corrected equalized signal. The phase correction may be based on a second, non-linearity compensated, inter-symbol correlated (ISC) feedback signal.

Abstract: A method and system for a sequence estimation in a receiver, such as for use when receiving a sample of a received inter-symbol correlated (ISC) signal corresponding to a transmitted vector of L symbols, with L being a integer greater than 1, and with symbol L being a most-recent symbol and symbol 1 being least recent symbol of the vector. A plurality of candidate vectors may be generated, wherein element L?m of each candidate vector holding one of a plurality of possible values of the symbol L?m, with m is an integer greater than or equal to 1, and elements L?m+1 through L of each candidate vectors holding determined filler values. A plurality of metrics may be generated based on the plurality of candidate vectors, and based on the generated plurality of metrics, a best one of the possible values of the symbol L?m may be selected.

Abstract: Methods and systems are provided for timing synchronization for reception of highly-spectrally efficient communications. An example method may include, mapping, in a transmitter, a plurality of transmit bits to a plurality of symbols at a symbol rate that is based on an oscillator signal. The plurality of symbols may be processed via a filter. The processing may result in an inter-symbol correlated (ISC) signal. The oscillator signal may be frequency divided to generate one or more pilot signals having a frequency that is a sub-harmonic of a frequency of the oscillator signal. The pilot signal may be injected into the ISC signal. The injecting may result in an ISC signal with timing carrier. The ISC signal with timing carrier may be transmitted. Gain of the one or more pilot signals may be adjusted based on a spectral mask value associated with the transmitting.

Abstract: A receiver receives an inter-symbol correlated (ISC) signal with information symbols and a corresponding parity symbol. Values of information symbols are estimated utilizing parity samples that are generated from the parity symbols. One or more maximum likelihood (ML) decoding metrics are generated for the information symbols. One or more estimations are generated for the information symbols based on the one or more ML decoding metrics. A parity metric is generated for each of the one or more generated estimations of the information symbols. The parity metric is generated by summing a plurality of values of one of the generated estimations to generate a sum, and wrapping the sum to obtain a parity check value that is within the boundaries of a symbol constellation utilized in generating the information symbols.

Abstract: A receiver may be operable to generate estimates of transmitted symbols using a sequence estimation process that may incorporate a non-linear model. The non-linear model may be adapted by the receiver based on particular communication information that may be indicative of non-linearity experienced by the transmitted symbols. The receiver may generate a reconstructed signal from the estimates of the transmitted symbols. The receiver may adapt the non-linear model based on values of an error signal generated from the reconstructed signal, and the values of the error signal may be generated from a portion of the generated estimates that may correspond to known symbols and/or information symbols. The values of the error signal corresponding to the known symbols may be given more weight in an adaptation algorithm, and the values of the error signal corresponding to the information symbols may be given less weight in the adaptation algorithm.

Abstract: Circuitry of a transmitter may comprise a predistortion circuit cascaded with a nonlinear circuit. The nonlinear circuit may be characterized by a first response corresponding to a first error vector magnitude. A response of the predistortion circuit may be configured based on the first response of the nonlinear circuit such that a composite response of the predistortion circuit cascaded with the nonlinear circuit differs from the first response and is characterized by a second error vector magnitude that is greater or equal than the first error vector magnitude. The response of the predistortion circuit may be configured based on feedback of an output of the nonlinear circuit. The response of the predistortion circuit may be configured based on parameters received from a receiver partner of the transmitter during connection setup, in preambles, in message headers, and/or in dedicated messages.

Abstract: A sequence estimation circuit of a receiver may receive a sample of an inter-symbol correlated (ISC) signal corresponding to a time instant when phase and/or amplitude of the ISC signal is a result of correlation among a plurality of symbols of a transmitted symbol sequence. The sequence estimation circuit may calculate a residual signal value based on the sample of the ISC signal and based on a survivor sequence. The sequence estimation circuit may generate one or more branch vector hypotheses based on the residual signal value, where each of the hypotheses comprises a plurality of symbols. The sequence estimation circuit may generate an estimate of one or more of the plurality of transmitted symbols based on the one or more branch vector hypotheses.