LLM-Viterbi: Semantic-Aware Decoding for Convolutional Codes

Fuente: arXiv
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Autores principales: Li, Zhengtong, Yue, Chentao, Hao, Jiafu, Vucetic, Branka, Li, Yonghui
Formato: Preprint
Publicado: 2026
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author Li, Zhengtong
Yue, Chentao
Hao, Jiafu
Vucetic, Branka
Li, Yonghui
author_facet Li, Zhengtong
Yue, Chentao
Hao, Jiafu
Vucetic, Branka
Li, Yonghui
contents Traditional wireless communications rely solely on bit-level channel coding for error correction, without exploiting the inherent linguistic structure of the data source. This paper proposes a large language model (LLM) Viterbi decoder that integrates LLM priors into the Viterbi decoding for text transmission over AWGN channels. The proposed decoder maintains multiple candidate paths during the Viterbi decoding and periodically evaluates path reliabilities using a fine-tuned Byte-level T5 (ByT5) language model. By combining channel reliability metrics with semantic probability from the LLM, it outputs the path that maximizes the joint likelihood of channel observations and linguistic coherence. Simulations show that our decoder achieves significant performance gains over conventional Viterbi decoding in terms of both block error rate (BLER) and semantic similarity. For convolutional codes with constraint length 3, it achieves approximately 1.5 dB more coding gain in BLER, with over 50% improvements in semantic similarity. The framework can extend to other structured data sources beyond text.
format Preprint
id arxiv_https___arxiv_org_abs_2604_19035
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle LLM-Viterbi: Semantic-Aware Decoding for Convolutional Codes
Li, Zhengtong
Yue, Chentao
Hao, Jiafu
Vucetic, Branka
Li, Yonghui
Information Theory
94B10, 68T50
E.4; I.2.7
Traditional wireless communications rely solely on bit-level channel coding for error correction, without exploiting the inherent linguistic structure of the data source. This paper proposes a large language model (LLM) Viterbi decoder that integrates LLM priors into the Viterbi decoding for text transmission over AWGN channels. The proposed decoder maintains multiple candidate paths during the Viterbi decoding and periodically evaluates path reliabilities using a fine-tuned Byte-level T5 (ByT5) language model. By combining channel reliability metrics with semantic probability from the LLM, it outputs the path that maximizes the joint likelihood of channel observations and linguistic coherence. Simulations show that our decoder achieves significant performance gains over conventional Viterbi decoding in terms of both block error rate (BLER) and semantic similarity. For convolutional codes with constraint length 3, it achieves approximately 1.5 dB more coding gain in BLER, with over 50% improvements in semantic similarity. The framework can extend to other structured data sources beyond text.
title LLM-Viterbi: Semantic-Aware Decoding for Convolutional Codes
topic Information Theory
94B10, 68T50
E.4; I.2.7
url https://arxiv.org/abs/2604.19035