Distributed source coding for satellite communications

Inspired by mobile satellite communications systems, we consider a source c oding system which consists of multiple sources, multiple encoders, and mul tiple decoders. Each encoder has access to a certain subset of the sources, each decoder has access to certain subset of the encoders, and each decode r reconstructs a certain subset of the sources almost perfectly. The connec tivity between the sources and the encoders, the connectivity between the e ncoders and the decoders, and the reconstruction requirements for the decod ers are all arbitrary. Our goal is to characterize the admissible coding ra te region. Despite the generality of the problem, we have developed an appr oach which enables us to study all cases on the same footing. We obtain inn er and outer bounds of the admissible coding rate region in terms of Gamma( N)* and <(Gamma)over bar>(N)*, respectively, which are fundamental regions in the entropy space recently defined by Yeung, So far, there has not been a full characterization of Gamma(N)*, so these bounds cannot be evaluated e xplicitly except for some special cases. Nevertheless, we obtain an alterna tive outer bound which can be evaluated explicitly. We show that this bound is tight for all the special cases for which the admissible coding rate re gion is known, The model we study in this paper is more general than all pr eviously reported models on multilevel diversity coding, and the tools we u se are new in multiuser,information theory.