Speaker: Dongning Guo

Title: Massive Access and Many-User Information Theory

Abstract: Classical multiuser information theory studies the fundamental limits of models with a fixed (often small) number of users as the coding blocklength goes to infinity. In this talk, we introduce a new regime, where the number of users and the blocklength tend to infinity simultaneously. This paradigm is motivated by systems in which the number of devices is comparable or far exceeds the blocklength, such as in large machine-to-machine communication systems and sensor networks. We focus on the Gaussian many-access channel, which consists of a single receiver and a massive number of transmitters, where a subset of users transmits in a given block and need to be identified as well as decoded. New notions of capacity are defined and characterized. We then briefly discuss many-broadcast channels and an outlook on a general many-user information theory. This is joint work with Xu Chen, Tsung-Yi Chen, Lei Zhang, and Jun Luo.