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arXiv · 1707.04850

Moderate Deviation Asymptotics for Variable-Length Codes with Feedback

Lan V. Truong·Vincent Y. F. Tan
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Abstract

We consider data transmission across discrete memoryless channels (DMCs) using variable-length codes with feedback. We consider the family of such codes whose rates are $\rho_N$ below the channel capacity $C$, where $\rho_N$ is a positive sequence that tends to zero slower than the reciprocal of the square root of the expectation of the (random) blocklength $N$. This is known as the moderate deviations regime and we establish the optimal moderate deviations constant. We show that in this scenario, the error probability decays sub-exponentially with speed $\exp(-(B/C)N\rho_N)$, where $B$ is the maximum relative entropy between output distributions of the DMC.

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Lan V. Truong, Vincent Y. F. Tan. 2017-07-16. Moderate Deviation Asymptotics for Variable-Length Codes with Feedback. https://arxiv.org/abs/1707.04850

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