Method and apparatus for symbol detection via reduced complexity sequence estimation processing
AssigneeTelefonaktiebolaget L M Ericsson (publ)
InventorGregory E. Bottomley
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Abstract
Teachings presented herein offer the performance advantages of sequence estimation for received signal symbol detection, while simultaneously providing potentially significant reductions in computational overhead. Initial demodulation of a received signal identifies a reduced number of candidate symbol values for all or a subset of a sequence of symbols represented in a received signal. A sequence estimation process, e.g., an MLSE process, constrains its state spaces to the reduced number of candidate symbols values, rather than considering all possible symbol values.
Claims20
A method of detecting a sequence of symbols in a received signal comprising:
- determining a reduced number of possible symbol values for the sequence of symbols by initially demodulating the received signal and detecting candidate symbol values for all or a subset of the sequence of symbols;
- detecting the sequence of received symbols by processing the received signal in a sequence estimation process that is constrained to the reduced number of possible symbol values;
- and
- adapting the initial demodulation of the received signal responsive to changing reception conditions by choosing one of two or more available types of received signal demodulation processes responsive to evaluating at least one of channel dispersion and received signal quality, wherein choosing one of two or more available types of received signal demodulation processes comprises choosing between a Rake-based demodulation process and a decision feedback equalization-based demodulation process based on evaluating at least one of channel dispersion and received signal quality.
A demodulator for detecting a sequence of symbols in a received signal comprising:
- an initial demodulator configured to determine a reduced number of possible symbol values for the sequence of symbols by initially demodulating the received signal and detecting candidate symbol values for all or a subset of the sequence of symbols;
- a sequence estimator configured to detect the sequence of received symbols by processing the received signal in a sequence estimation process that is constrained to the reduced number of possible symbol values;
- and
- a control processor configured to evaluate at least one of channel dispersion and received signal quality, and to correspondingly select which one of two available types of initial demodulation processes is to be used by the initial demodulator for initially demodulating the received signal based on the evaluation, wherein the two available types of initial demodulation processes include a Rake-based demodulation process and a decision feedback equalization-based demodulation process.
Dependencies are inferred from the claim text.