Method and Apparatus for Nonlinear-Channel Identification and Estimation of Nonlinear-Distorted Signals

1. A method for producing a distorted-signal estimate in a communication system having a plurality of discrete-time source signals that have been transmitted over a discrete-time non-linear channel that produces a distorted-constellation signal, comprising: receiving, at a receiver, a received signal, wherein the received signal comprises a receiver-noise signal and the distorted-constellation signal that is produced from the plurality of discrete-time source signals, each of which is a result of modulation of digital data to a complex constellation value, that have been passed through the discrete-time non-linear channel to produce the transmission signal; phase-rotating, by a block generator, the plurality of discrete-time source signals, each of which has been selected from a finite complex constellation, in a block of K successive source signals by a phase rotation value to produce a plurality of rotated-source signals, wherein the phase rotation value is a function of a phase of a sequence-aligned source signal which is produced by sequence aligning one of the plurality of source signals within the block of K successive source signals with the received signal, wherein K is a positive real number or value; producing, by an estimator signal generator, a plurality of estimator signals, each of which is a product of one or more real values of a signal combination product selected from the plurality of rotated-source signals; multiplying, by a dot-product multiplier, each of the plurality of estimator signals by an associated estimator weight and summing the products to produce a rotated estimate; and subtracting, by a controller, the phase rotation value from a phase of the rotated estimate to produce the distorted-signal estimate of the distorted-constellation signal.

2. The method of claim 1 , wherein block length K is odd and the sequence-aligned source signal is a center source signal within the block of K successive source signals and the source signals before and after the center source signal are identified by early and late words, respectively, each word having an associated word weight measure, and wherein the rotated-source signals are complex-conjugate reversed based on a comparison of early and late word weight measures.

3. The method of claim 1 , wherein block length K is even and the sequence-aligned source signal is selected as one of two center signals within the block of K successive source signals, the source signals of successive K/2 signals within the block are identified by early and late words, respectively, each word having an associated word weight measure, and wherein the rotated-source signals are complex-conjugate reversed based on a comparison of early and late word weight measures.

4. The method of claim 1 , wherein the constellation is a constant envelope and the phase rotation value is equal to the complex conjugate of the sequence-aligned source signal in the block of K successive source signals.

5. The method of claim 4 , wherein the estimator weights are calculated by a Least-Mean-Squares direct solution that multiplies a precomputed matrix of estimator signals and a vector of previous output signals that have been phase-rotated by the phase rotation value.

6. A signal estimator for producing a distorted-signal estimate in a communication system having a plurality of discrete-time source signals that have been transmitted over a discrete-time non-linear channel that produces a distorted-constellation signal, comprising: a receiver for receiving a received signal, wherein the received signal comprises a receiver-noise signal and the distorted-constellation signal that is produced from the plurality of discrete-time source signals, each of which is a result of modulation of digital data to a complex constellation value, that have been passed through the discrete-time non-linear channel to produce the transmission signal; a block generator for phase-rotating the plurality of discrete-time source signals, each of which has been selected from a finite complex constellation, in a block of K successive source signals by a phase rotation value to produce a plurality of rotated-source signals, wherein the phase rotation value is a function of a phase of a sequence-aligned source signal which is produced by sequence aligning one of the plurality of source signals within the block of K successive source signals with the received signal, wherein K is a positive real number or value; an estimator signal generator for producing a plurality of estimator signals, each of which is a product of one or more real values of a signal combination product selected from the plurality of rotated-source signals; an estimator weight calculator for calculating an associated estimator weight value for the plurality of estimator signals; and a dot-product multiplier for multiplying each of the plurality of estimator signals by the associated estimator weight value and summing the products to produce a rotated estimate and for further multiplying the rotated estimate by the complex conjugate of the rotation value to produce the distorted-signal estimate of the distorted-constellation signal.

7. The signal estimator of claim 6 , wherein block length K is odd and the sequence-aligned source signal is a center source signal within the block of K successive source signals and where the block generator produces source signals before and after the center signal that are identified by early and late words, respectively, each word having an associated word weight measure, and wherein the rotated-source signals are complex-conjugate reversed based on a comparison of early and late word weight measures.

8. The signal estimator of claim 6 , wherein block length K is even and the sequence-aligned source signal is selected as one of two center signals within the block of K successive source signals, the source signals of successive K/2 signals within the block are identified by early and late words, respectively, each word having an associated word weight measure, and wherein the rotated-source signals are complex-conjugate reversed based on a comparison of early and late word weight measures.

9. The signal estimator of claim 6 , wherein the constellation has a constant envelope and the phase rotation value is equal to the complex conjugate of the sequence-aligned source signal in the block of K successive source signals.

10. The signal estimator of claim 9 , wherein the estimator weight calculator includes multiplication of a precomputed matrix of estimator signals and a vector of previous output signals, that have been phase-rotated by the rotation value, to produce the estimator weights.