US 6,690,723 B1 · Decision-aided equalizer

Abstract

In a method for channel equalization a communications receiver receives an input data stream comprising modulation symbols. A reduced set sequence estimation algorithm produces intermediate hard decisions, based on the input data stream and on a channel reference, which are applied to a decision feedback filter in a feedback loop. Soft output sequences of emitted symbols are also produced, based on the input data stream, which are decoded, error-corrected and re-encoded. The error-corrected soft output sequences are iteratively applied to the decision feedback filter, such that a channel equalized received data stream is generated based on both the feedback soft output sequences and the intermediate hard decisions. An iterative decision-aided equalizer is also described. In this manner, errors corrected by the decoder are not re-introduced into the decision feedback filter, hereby reducing the effect of error propagation in decision-aided feedback equalizers.

Claims11

Dependent claims

A method for channel equalization in a communications receiver comprising:

receiving an input data stream comprising modulation symbols;
employing a reduced set sequence estimation algorithm to produce intermediate hard decisions based on the input data stream and on a channel reference;
applying the intermediate hard decisions into a decision feedback filter in a feedback loop,
producing soft output sequences of symbols based on the input data stream;
decoding and error-correcting the soft output sequences re-encoding the error-corrected soft output sequences;
applying the re-encoded error-corrected soft output sequences iteratively into the decision feedback filter;
and
generating a channel equalized received data stream based on both the re-encoded error-corrected soft output sequences and the intermediate hard decisions.

5 more elements

An iterative decision-aided equalizer comprising:

a decision feedback equalizer having:
a processor employing a reduced set sequence estimation algorithm for receiving an input data stream comprising modulation symbols, and providing intermediate hard decisions based on the input data stream and on a channel reference;
a decision feedback filter coupled to an output of the processor;
and
a summing device for summing an output of the decision feedback filter with the input data stream to produce soft outputs representing the received symbols;
a feedback loop, for receiving soft outputs from the summing device and iteratively providing error-corrected soft outputs to the decision feedback filter, comprising:
a decoder for decoding and error-correcting the soft outputs;
an encoder for encoding the error-corrected sequence of soft outputs,
wherein the feedback loop iteratively applies the encoded error-corrected soft outputs to the decision feedback filter to generate a channel equalized received data stream.

6 more elements

Dependencies are inferred from the claim text.

Decision-aided equalizer

Life of this patent

Decision-aided equalizer

Life of this patent

Abstract

Claims11