Architecture for communication with a fidelity criterion in unknown networks

We prove that in order to communicate independent sources (this is the unicast problem) between various users over an unknown medium to within various distortion levels, it is sufficient to consider source-channel separation based architectures: architectures which first compress the sources to within the corresponding distortion levels followed by reliable communication over the unknown medium. We are reducing the problem of universal rate-distortion communication of independent sources over a network to the universal reliable communication problem over networks. This is a reductionist view. We are not solving the reliable communication problem in networks.