Cloud radio access networks (C-RANs) emerge as appealing architectures for next-generation wireless/cellular systems whereby the processing/decoding is migrated from the local base-stations/radio units (RUs) to a control/central units (CU) in the "cloud". Fog radio access networks (F-RAN) address the case where the RUs are enhanced by having the ability of local caching of popular contents. The network operates via fronthaul digital links connecting the CU and the RUs. In this talk we will address basic information theoretic aspects of such networks, with emphasis of simple oblivious processing. Theoretical results illustrate the considerable performance gains to be expected for different cellular models. Some interesting theoretical directions conclude the presentation.