Rate Splitting, Superposition Coding and Binning for Groupcasting over the Broadcast Channel: A General Framework

Abstract: A general inner bound is given for the discrete memoryless broadcast channel with an arbitrary number of users and general message sets, a setting that accounts for the most general form of concurrent groupcasting, with messages intended for any set of subsets of receivers. Achievability is based on superposition coding and rate-splitting without and with binning, where each receiver jointly decodes both its desired messages as well as the partial interference assigned to it via rate-splitting. The proof of achievability builds on the techniques for the description and analysis of superposition coding recently developed by the authors for the multiple-access channel with general messages as well as a new recursive mutual covering lemma for the analysis of the more general achievable scheme with binning.