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Main Authors: Hamdi, Yassine, Gündüz, Deniz
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.15757
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author Hamdi, Yassine
Gündüz, Deniz
author_facet Hamdi, Yassine
Gündüz, Deniz
contents We consider the problem of synthesizing a memoryless channel between an unobserved source and a remote terminal. An encoder has access to a partial or noisy version $Z^n = (Z_1, \ldots, Z_n)$ of a remote source sequence $X^n = (X_1, \ldots, X_n),$ with $(X_i,Z_i)$ independent and identically distributed with joint distribution $q_{X,Z}.$ The encoder communicates through a noiseless link to a decoder which aims to produce an output $Y^n$ coordinated with the remote source; that is, the total variation distance between the joint distribution of $X^n$ and $Y^n$ and some i.i.d. target distribution $q_{X,Y}^{\otimes n}$ is required to vanish as $n$ goes to infinity. The two terminals may have access to a source of rate-limited common randomness. We present a single-letter characterization of the optimal compression and common randomness rates. We also show that when the common randomness rate is small, then in most cases, coordinating $Z^n$ and $Y^n$ using a standard channel synthesis scheme is strictly sub-optimal. In other words, schemes for which the joint distribution of $Z^n$ and $Y^n$ approaches a product distribution asymptotically are strictly sub-optimal.
format Preprint
id arxiv_https___arxiv_org_abs_2507_15757
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Remote Channel Synthesis
Hamdi, Yassine
Gündüz, Deniz
Information Theory
We consider the problem of synthesizing a memoryless channel between an unobserved source and a remote terminal. An encoder has access to a partial or noisy version $Z^n = (Z_1, \ldots, Z_n)$ of a remote source sequence $X^n = (X_1, \ldots, X_n),$ with $(X_i,Z_i)$ independent and identically distributed with joint distribution $q_{X,Z}.$ The encoder communicates through a noiseless link to a decoder which aims to produce an output $Y^n$ coordinated with the remote source; that is, the total variation distance between the joint distribution of $X^n$ and $Y^n$ and some i.i.d. target distribution $q_{X,Y}^{\otimes n}$ is required to vanish as $n$ goes to infinity. The two terminals may have access to a source of rate-limited common randomness. We present a single-letter characterization of the optimal compression and common randomness rates. We also show that when the common randomness rate is small, then in most cases, coordinating $Z^n$ and $Y^n$ using a standard channel synthesis scheme is strictly sub-optimal. In other words, schemes for which the joint distribution of $Z^n$ and $Y^n$ approaches a product distribution asymptotically are strictly sub-optimal.
title Remote Channel Synthesis
topic Information Theory
url https://arxiv.org/abs/2507.15757