Broadcom Corporation

Steve A Allpress

Quinn Li

An apparatus and method for implementing an equalizer which (1) combines the benefits of a decision feedback equalizer (DFE) with a maximum-a-posterori (MAP) equalizer (or a maximum likelihood sequence estimator, MLSE) (2) performs equalization in a time-forward or time-reversed manner based on the channel being minimum-phase or maximum-phase to provide an equalization device with significantly lower complexity than a full-state MAP device, but which still provides improved performance over a conventional DFE. The equalizer architecture includes two DFE-like structures, followed by a MAP equalizer. The first DFE forms tentative symbol decisions. The second DFE is used thereafter to truncate the channel response to a desired memory of Lsymbols, which is less than the total delay spread of L symbols of the channel. The MAP equalizer operates over a channel with memory of Lsymbols (where L&#x3c;=L), and therefore the overall complexity of the equalizer is significantly reduced.

High performance equalizer with enhanced DFE having reduced complexity

This invention describes an apparatus and method to improve the performance of a decision feedback equalizer (DFE) for time-varying multi-path channels. For minimum-phase channels, the equalization is performed in a time-forward manner. For maximum-phase channels, the equalization is performed in a time-reversed manner. More specifically, for maximum-phase channels, the filter coefficients are computed based on the channel estimates reversed in time, and the filtering and equalization operations are performed with the received block of symbols in a time-reversed order. In the context of this invention, the term 'minimum-phase channel' implies that the energy of the leading part of the channel profile is greater than the energy of the trailing part. The term 'maximum-phase channel' implies that the energy of the leading part of the channel profile is less than the energy of the trailing part.

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Hoboken, NJ, United States of America

Steve A Allpress