Common Randomness Generation from Finite Compound Sources
Rami Ezzine, Moritz Wiese, Christian Deppe, Holger Boche
TL;DR
This paper addresses generating common randomness from finite compound sources with one-way, rate-limited communication. It introduces a single-letter framework yielding a lower bound and an upper bound on the compound CR capacity $C_{CCR}(R)$, governed by auxiliary variables $U$ that satisfy Markov chains with the source observations and a constraint $I(U;X)- min_s I(U;Y_s) \\le R$. The bounds collapse to $H(X)$ when $R$ is large enough (specifically $R \\ge \max_s H(X|Y_s)$), and two corollaries show additional scenarios where the bounds are tight. The results extend classical two-source CR capacity concepts to compound-source uncertainty, providing fundamental limits for CR generation under source-state ambiguity in one-way communication settings.
Abstract
We investigate the problem of generating common randomness (CR) from finite compound sources aided by unidirectional communication over rate-limited perfect channels. The two communicating parties, often referred to as terminals, observe independent and identically distributed (i.i.d.) samples of a finite compound source and aim to agree on a common random variable with a high probability for every possible realization of the source state. Both parties know the set of source states as well as their statistics. However, they are unaware of the actual realization of the source state. We establish a single-letter lower and upper bound on the compound CR capacity for the specified model. Furthermore, we present two special scenarios where the established bounds coincide.
