A convolutional decoder includes a first storage, a second storage, a branch metric processor to determine branch metrics for transitions of states from a start step to a last step according to input bit streams, an ACS processor to select maximum likelihood path metrics to determine a survival path according to the branch metrics and to update states of the start step to the first storage and the second storage alternately based on the selection of the maximum likelihood path metrics, and a trace back logic to selectively trace back the survival path based on the states of the start step stored in a selected storage among the first storage and the second storage.

A decoding method for a convolutionally coded signal is provided. The convolutionally coded signal includes a trellis. The decoding method includes determining a plurality of first sub-trellises from the trellis, decoding the first sub-trellises, determining a plurality of second sub-trellises from the trellis, boundaries of the second sub-trellises being different from boundaries of the first sub-trellises, and decoding the second sub-trellises.

A electronic system includes: a support chip configured to receive an input code stream; a circular Viterbi mechanism, coupled to the support chip, configured to: generate a final path metric for the input code stream, store intermediate path metrics at the repetition depth, generate a repetition path metric for the input code stream, and calculate a soft correlation metric based on the final path metric, the repetition path metric, and the intermediate path metrics.

Certain aspects of the present disclosure relate to techniques and apparatus for enhanced decoding, for example, by providing a multi-phase tail biting convolutional code (TBCC) decoding algorithm. An exemplary method generally includes obtaining, via a wireless medium, a codeword encoded with a TBCC encoding scheme, generating metrics for candidate paths through trellis stages of a decoder, propagating information from at least one of the trellis stages to a later trellis stage, while generating the metrics, selecting a set of the candidate paths based on the propagated information, and decoding the encoded codeword by evaluating the selected set of candidate paths based, at least in part, on the generated metrics. Other aspects, embodiments, and features are claimed and described.

A convolutional decoder includes a first storage, a second storage, a branch metric processor to determine branch metrics for transitions of states from a start step to a last step according to input bit streams, an ACS processor to select maximum likelihood path metrics to determine a survival path according to the branch metrics and to update states of the start step to the first storage and the second storage alternately based on the selection of the maximum likelihood path metrics, and a trace back logic to selectively trace back the survival path based on the states of the start step stored in a selected storage among the first storage and the second storage.

Decoding of a first message is disclosed, wherein first and second messages are encoded by a code (represented by a state machine) to produce first and second code words, which are received over a communication channel. A plurality of differences (each corresponding to a hypothesized value of a part of the first message) between the first and second messages are hypothesized. An initial code word segment is selected having, as associated previous states, a plurality of initial states (each associated with a hypothesized difference and uniquely defined by the hypothesized value of the part of the first message). The first message is decoded by (for each code word segment, starting with the initial code word segment): combining the code word segment of the first code word with a transformed (based on the hypothesized difference of the initial state associated with the previous state of the state transition corresponding to a first message segment content) code word segment of the second code word to produce a combined code word segment, determining a decision metric associated with a probability that the combined code word segment corresponds to the first message segment content, and selecting (for the first message) the first message segment content or a second message segment content based on the decision metric. If the first message segment content is selected, the subsequent state of the state transition corresponding to the first message segment content is associated with the initial state associated with the previous state of the state transition.

An embodiment encoder device for encoding an information word c=[c.sub.0, c.sub.1, . . . , c.sub.K1] having K information bits, c.sub.i, includes an encoder for a tail biting convolutional code having a constraint length, L, where K<L1; the encoder being configured to receive the K information bits; and encode the K information bits so as to provide an encoded code word. An embodiment decoder device for determining an information word c=[c.sub.0, c.sub.1, . . . , c.sub.K1], having K information bits, c.sub.i, includes a decoder for a tail biting convolutional code having a constraint length, L, where K<L1; the decoder being configured to: receive an input sequence; compute at least one reliability parameter based on the received input sequence; and determine an information word c based on the at least one reliability parameter.

Aspects of the disclosure relate to a channel coding and decoding algorithm that provides for generalized polar codes, including the concatenation of a plurality of component codes via one-step polarization. In a further aspect, selection of suitable component codes in this scheme can result in a generalized polar code having a cyclic shift property, such that information can be implicitly communicated according to the magnitude of the cyclic shift. In yet another aspect, a decoding algorithm provides for reliable decoding of such generalized polar codes, including exploitation of time diversity in sequential transmissions. Other aspects, embodiments, and features are also claimed and described.

Calculating path metrics, associated with respective states of an n-state trellis, by accumulating branch metrics in a sequence detector. Each path metric is represented by N bits plus a wrap-around bit for indicating wrap-around of the N-bit value of that path metric.

Decoding of a first message is disclosed, wherein first and second messages are encoded by a code (represented by a state machine) to produce first and second code words, which are received over a communication channel. A plurality of differences (each corresponding to a hypothesized value of a part of the first message) between the first and second messages are hypothesized. An initial code word segment is selected having, as associated previous states, a plurality of initial states (each associated with a hypothesized difference and uniquely defined by the hypothesized value of the part of the first message). The first message is decoded by (for each code word segment, starting with the initial code word segment): determining first and second metrics associated with respective probabilities that the code word segment of the first and second code word (respectively) corresponds to a first message segment content, the probability of the second metric being conditional on the hypothesized difference of the initial state associated with the previous state of the state transition corresponding to the first message segment content, determining a decision metric by combining the first and second metrics, and selecting (for the first message) the first message segment content or a second message segment content based on the decision metric. If the first message segment content is selected, the subsequent state of the state transition corresponding to the first message segment content is associated with the initial state associated with the previous state of the state transition.