Early-termination of decoding convolutional codes
AssigneeIntel Corporation
InventorsDavid Arditti Ilitzky, Thomas A. Tetzlaff
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Abstract
A decoder having an input configured to receive a sequence of softbits presumed to correspond to a convolutionally-encoded codeword; and a decoding circuit configured to: determine, as part of a decoding process, a Maximum Likelihood (ML) survivor path in a trellis representation of the codeword; determine whether the presumed convolutionally-encoded codeword meets an early-termination criteria; and abort the decoding process if the presumed convolutionally-encoded codeword meets the early-termination criteria, continue the decoding process if the presumed convolutionally-encoded codeword fails to meet the early-termination criteria.
Claims17
A decoder, comprising:
- an input configured to receive a sequence of softbits presumed to correspond to a convolutionally-encoded codeword;
- and
- a decoding circuit configured to execute, for the received sequence of softbits, a Viterbi-based algorithm to:
- determine, as part of a decoding process, a Maximum Likelihood (ML) survivor path in a trellis representation of the codeword;
- determine whether the presumed convolutionally-encoded codeword meets an early-termination criteria;
- abort execution of the Viterbi-based algorithm for the received sequence of softbits to stop the decoding process if the presumed convolutionally-encoded codeword meets the early-termination criteria irrespective of a number of survivor path update iterations that have already been performed such that the received sequence of softbits are not further processed as part of a decoder operation and the ML survivor path is not decoded;
- and
- continue the decoding process if the presumed convolutionally-encoded codeword fails to meet the early-termination criteria,
- wherein the early-termination criteria indicates that the codeword is ill-formed based upon an assessed likelihood of the received sequence of softbits being a correctly encoded codeword,
- wherein the early-termination criteria includes a heuristic classification based on a distribution of survivor-path initial states, and
- wherein the decoding circuit is configured to determine a metric based upon the distribution of survivor-path initial states, and to determine whether the codeword is ill-formed based upon comparison of the metric to a threshold, thereby classifying between correctly-formed and ill-formed codewords.
A decoding method, comprising:
- receiving, at an input of a decoder, a sequence of softbits presumed to correspond to a convolutionally-encoded codeword;
- executing, by the decoder for the received sequence of softbits, a Viterbi-based algorithm for:
- determining a Maximum Likelihood (ML) survivor path in a trellis representation of the codeword;
- determining whether the presumed convolutionally-encoded codeword meets an early-termination criteria;
- aborting execution of the Viterbi-based algorithm for the received sequence of softbits to stop the decoding process if the presumed convolutionally-encoded codeword meets the early-termination criteria irrespective of a number of survivor path update iterations that have already been performed such that the received sequence of softbits are not further processed as part of a decoder operation and the ML survivor path is not decoded;
- and
- continuing the decoding method if the presumed convolutionally-encoded codeword fails to meet the early-termination criteria,
- wherein the early-termination criteria indicates that the codeword is ill-formed based upon an assessed likelihood of the received sequence of softbits being a correctly encoded codeword,
- wherein the early-termination criteria includes a heuristic classification based on a distribution of survivor-path initial states, and
- wherein the act of determining whether the presumed convolutionally-encoded codeword meets the early-termination criteria includes determining a metric based upon the distribution of survivor-path initial states, and determining whether the codeword is ill-formed based upon comparison of the metric to a threshold, thereby classifying between correctly-formed and ill-formed codewords.
Dependencies are inferred from the claim text.