In this paper we analyze the joint rate distortion function (RDF), for a tuple of correlated sources taking values in abstract alphabet spaces (i.e., continuous) subject to two individual distortion criteria. First, we derive structural properties of the realizations of the reproduction Random Variables (RVs), which induce the corresponding optimal test channel distributions of the joint RDF. Second, we consider a tuple of correlated multivariate jointly Gaussian RVs, X 1 : Ω → R p 1 , X 2 : Ω → R p 2 with two square-error fidelity criteria, and we derive additional structural properties of the optimal realizations, and use these to characterize the RDF as a convex optimization problem with respect to the parameters of the realizations. We show that the computation of the joint RDF can be performed by semidefinite programming. Further, we derive closed-form expressions of the joint RDF, such that Gray's [1] lower bounds hold with equality, and verify their consistency with the semidefinite programming computations.
I. LITERATURE REVIEW, PROBLEM FORMULATION, AND MAIN CONTRIBUTIONS
A. Literature ReviewGray [1, Theorem 3.1, Corollary 3.1] derived lower bounds on the joint rate distortion functions (RDFs), of a tuple of Random Variables (RVs) taking values in arbitrary, abstract spaces, X 1 : Ω → X 1 , X 2 : Ω → X 2 , with a weighted distortion, expressed in terms of conditional RDFs, and marginal RDFs. Gray and Wyner in [2], characterized the rate distortion region of a tuple of correlated RVs, using the joint, conditional and marginal RDFs. Xiao and Luo [3, Theorem 6] derived the closed-form expression of the joint RDF for a tuple of scalar-valued correlated Gaussian RVs, with two square-error distortion criteria, while Lapidoth and Tinguely [4] re-derived Xiao's and Luo's joint RDF using an alternative method. Xu, Liu and Chen [5] and Viswanatha, Akyol and Rose [6], generalized Wyner's common information [7] to its lossy counterpart, as the minimum common message rate on the Gray and Wyner rate region with sum rate equal to the joint RDF with two individual distortion functions. The analysis in [5], [6], includes the application of a tuple of scalar-valued, jointly Gaussian RVs. More recent work on rates that lie on the Gray and Wyner rate region are found in [8].
SourceEncoder: f E (•)