High-speed analog-to-digital conversion with improved robustness to timing uncertainty
AssigneeQuellan, Inc.
InventorsAndrew Joo Kim, Stephen E. Ralph, Sanjay Bajekal
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Abstract
A method and system using the principle of generalized maximum likelihood estimation to resolve sample timing uncertainties that are associated with the decoding of communication signals. By using generalized maximum likelihood estimation, sample timing uncertainty can be resolved by taking multiple samples of the received signal within a symbol period and determining which sample best corresponds to the optimal sample timing. The sample which best corresponds to the optimal sample timing can be determined from a timing index which can be calculated from ambiguity indicators that are based on the samples of the received signal.
Claims20
A decoding unit for decoding a received signal comprising:
- a plurality of soft-decoders, each soft-decoder sampling the received signal at a different time within a symbol period and outputting two values, the first value comprising a preliminary decoded value and the second value comprising an ambiguity indicator;
- and
- a logic device coupled to the each of the soft-decoders, for determining a decoded value for each symbol based on one or more preliminary decoded values and ambiguity indicators.
A decoding unit for decoding a received signal comprising:
- an asynchronous soft-decoder that continuously samples the received signal;
- a plurality of first delay elements coupled to a first soft-decoder, each first delay element generating a different delay relative to another first delay element and producing a first ambiguity indicator;
- a plurality of second delay elements coupled to a second soft-decoder output, each second delay element generating a different delay relative to another second delay element and producing a preliminary decoded output;
- and
- a logic device coupled to the each of the delay elements, for determining a decoded value based on one or more the preliminary decoded output and ambiguity indicators.
A decoding unit for decoding a received signal comprising:
- an analog-to-digital converter for sampling the received signal faster than once every symbol period of the received signal;
- a processor coupled to the converter for grouping a subset of sampled values derived from the single symbol period, for examining the subset of values and determining a value closest to an optimum sampling time based on a principle of generalized maximum likelihood, for decoding the value closest to the optimum sampling time and outputting that sample as the decoded symbol.
A method for decoding a received signal comprising:
- receiving a signal;
- estimating an optimal timing offset on a symbol-by-symbol basis;
- and
- decoding the communicated signal using generalized maximum likelihood estimation with the estimated optimal timing offset.
Dependencies are inferred from the claim text.