Sequential Decoding of Convolutional Codes for Synchronization Errors

Fuente: arXiv
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Hauptverfasser: Banerjee, Anisha, Lenz, Andreas, Wachter-Zeh, Antonia
Format: Preprint
Veröffentlicht: 2022
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author Banerjee, Anisha
Lenz, Andreas
Wachter-Zeh, Antonia
author_facet Banerjee, Anisha
Lenz, Andreas
Wachter-Zeh, Antonia
contents Sequential decoding, commonly applied to substitution channels, is a sub-optimal alternative to Viterbi decoding with significantly reduced memory costs. In this work, a sequential decoder for convolutional codes over channels that are prone to insertion, deletion, and substitution errors, is described and analyzed. Our decoder expands the code trellis by a new channel-state variable, called drift state, as proposed by Davey and MacKay. A suitable decoding metric on that trellis for sequential decoding is derived, generalizing the original Fano metric. The decoder is also extended to facilitate the simultaneous decoding of multiple received sequences that arise from a single transmitted sequence. Under low-noise environments, our decoding approach reduces the decoding complexity by a couple orders of magnitude in comparison to Viterbi's algorithm, albeit at slightly higher bit error rates. An analytical method to determine the computational cutoff rate is also suggested. This analysis is supported with numerical evaluations of bit error rates and computational complexity, which are compared with respect to optimal Viterbi decoding.
format Preprint
id arxiv_https___arxiv_org_abs_2201_11935
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Sequential Decoding of Convolutional Codes for Synchronization Errors
Banerjee, Anisha
Lenz, Andreas
Wachter-Zeh, Antonia
Information Theory
Sequential decoding, commonly applied to substitution channels, is a sub-optimal alternative to Viterbi decoding with significantly reduced memory costs. In this work, a sequential decoder for convolutional codes over channels that are prone to insertion, deletion, and substitution errors, is described and analyzed. Our decoder expands the code trellis by a new channel-state variable, called drift state, as proposed by Davey and MacKay. A suitable decoding metric on that trellis for sequential decoding is derived, generalizing the original Fano metric. The decoder is also extended to facilitate the simultaneous decoding of multiple received sequences that arise from a single transmitted sequence. Under low-noise environments, our decoding approach reduces the decoding complexity by a couple orders of magnitude in comparison to Viterbi's algorithm, albeit at slightly higher bit error rates. An analytical method to determine the computational cutoff rate is also suggested. This analysis is supported with numerical evaluations of bit error rates and computational complexity, which are compared with respect to optimal Viterbi decoding.
title Sequential Decoding of Convolutional Codes for Synchronization Errors
topic Information Theory
url https://arxiv.org/abs/2201.11935