Feedback Does Not Increase the Capacity of Approximately Memoryless Surjective POST Channels

Fuente: arXiv
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Autores principales: Zhang, Xiaojing, Chen, Jun, Wang, Guanghui
Formato: Preprint
Publicado: 2026
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author Zhang, Xiaojing
Chen, Jun
Wang, Guanghui
author_facet Zhang, Xiaojing
Chen, Jun
Wang, Guanghui
contents We study a class of finite-state channels, known as POST channels, in which the previous channel output serves as the current state. A POST channel is deemed approximately memoryless when the state-dependent transition matrices are sufficiently close to one another. For this family of channels, under a surjectivity condition on the associated memoryless reference channel, we show that the feedback capacity coincides with the non-feedback capacity. Consequently, for almost all approximately memoryless POST channels whose input alphabet size is no smaller than the output alphabet size, feedback provides no capacity gain. This result extends Shannon's classical theorem on discrete memoryless channels and demonstrates that the phenomenon holds well beyond the strictly memoryless case.
format Preprint
id arxiv_https___arxiv_org_abs_2603_08886
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Feedback Does Not Increase the Capacity of Approximately Memoryless Surjective POST Channels
Zhang, Xiaojing
Chen, Jun
Wang, Guanghui
Information Theory
Systems and Control
We study a class of finite-state channels, known as POST channels, in which the previous channel output serves as the current state. A POST channel is deemed approximately memoryless when the state-dependent transition matrices are sufficiently close to one another. For this family of channels, under a surjectivity condition on the associated memoryless reference channel, we show that the feedback capacity coincides with the non-feedback capacity. Consequently, for almost all approximately memoryless POST channels whose input alphabet size is no smaller than the output alphabet size, feedback provides no capacity gain. This result extends Shannon's classical theorem on discrete memoryless channels and demonstrates that the phenomenon holds well beyond the strictly memoryless case.
title Feedback Does Not Increase the Capacity of Approximately Memoryless Surjective POST Channels
topic Information Theory
Systems and Control
url https://arxiv.org/abs/2603.08886