Lucent Technologies Inc.

Agere Systems Inc.

Jian Yang

Jean-Jacques Werner

Patrik Larsson

A receiver, comprising an adaptive filter, performs blind equalization using a modified form of the constant modulus algorithm (CMA). This modified form of CMA is referred to as symbol CMA (SCMA). SCMA utilizes both the constant R and the sliced symbols, &Acirc; , in performing blind equalization. The constant R is statistically created to the sliced symbols, &Acirc; . The adaptive filter is a two-filter structure. The SCMA blind equalization technique reduces the rate of occurrence of a diagonal solution.

Blind equalization algorithm with the joint use of the constant R and the sliced symbols

A receiver, comprising an adaptive filter, performs blind equalization using a modified form of the constant modulus algorithm (CMA). This modified form of CMA is referred to as phase compensating CMA (PC-CMA). PC-CMA includes a phase-compensating term in the tap updating algorithm of the equalizer such that convergence to a straight constellation is achieved without the need of a rotator.

Phase-compensating constant modulus algorithm

In an Asymmetric Digital Subscriber Loop (ADSL) Discrete Multi-Tone (DMT) system, a DMT receiver uses, during start-up, an automatic gain control (AGC) element and a rotator element in place of a one-tap complex finite impulse response (FIR) filter.

Fast start-up in discrete multi-tone (DMT) based communications system

A receiver, comprising an adaptive filter, performs blind equalization using a joint constant modulus algorithm&mdash;multimodulus algorithm (CMA-MMA) blind equalization algorithm. The adaptive filter is a two-filter structure. The receiver performs CMA-MMA blind equalization using asymmetric algorithms. This joint CMA-MMA blind equalization technique reduces the rate of occurrence of a diagonal solution.

Blind equalization algorithm with joint use of the constant modulus algorithm and the multimodulus algorithm

A receiver has a dual mode of operation&mdash;a carrierless amplitude modulation/phase modulation (CAP) mode and a quadrature amplitude modulation (QAM) mode-yet only requires a single equalizer structure for both the CAP mode of operation and the QAM mode of operation during blind start-up. The receiver uses the same blind equalization updating algorithm independent of the type of received signal for converging the equalizer structure. The blind equalization updating algorithm incorporates a constant R, whose value is a function of the type of received signal, e.g., a QAM signal or a CAP signal. The type of received signal is determined as a function of the in-phase component of the mean-squared error, E&lsqb;e,.

Blind start-up of a dual mode CAP-QAM receiver

A blind convergence technique is restricted to using a subset of equalizer output samples. Illustratively, a receiver implements a windowed MMA approach. In this windowed MMA approach, a sample window overlays the two-dimensional plane representing the set of equalizer output samples. Only those equalizer output samples appearing within the sample window are used during filter adaptation.

Windowing technique for blind equalization

A decision feedback equalizer (DFE) comprises a feed-forward filter and a feedback filter. Blind training of the DFE is performed using a statistical-based tap updating algorithm for the feed-forward filter, and a symbol-based type of tap updating algorithm for the feedback filter.

Blind training of a decision feedback equalizer

A generalized form of a multimodulus algorithm (GMMA) is described for use in blind equalization. A receiver uses a signal point constellation representing 256 levels. This signal space is divided into sample, or data, subsets. Cost function minimization is done with respect to each sample subset.

Generalized multimodulus technique for blind equalization

A blind equalization cost function called the 'constrained Hilbert cost function' (CHCF) provides for reliable blind convergence of a two-filter equalizer structure. In particular, the CHCF cost function is designed in such a way that the two filters are constrained to be a Hilbert pair. Advantageously, this technique can be used with any blind equalization algorithms, such as RCA, CMA, and MMA.

Technique for improving the blind convergence of a two-filter adaptive

A blind equalization technique uses both the 'constant modulus algorithm' (CMA) and the 'multimodulus algorithm' (MMA) during blind start-up. This approach provides the basis for a 'transition algorithm.' One example of a transition algorithm is the CMA-MMA transition algorithm in which an adaptive filter simply switches from CMA to MMA. Other examples are variations of the CMA-MMA transition algorithm and are illustrated by the 'Constant Rotation CMA-MMA' transition algorithm and the 'Dynamic Rotation CMA-MMA' transition algorithm.

Technique for improving the blind convergence of an adaptive equalizer

A blind equalization technique--the multimodulus algorithm (MMA)--adapts coefficients of an equalizer so as to minimize dispersion of the output samples of the equalizer around piecewise linear contours of a signal space. The MMA technique is illustrated in the context of both square and non-square signal point constellations.

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Marlboro, NJ, United States of America

Jian Yang