Thursday Poster Symposium

The AWGN broadcast channel in the finite blocklength regime.

Paul Sheldon

Paul Sheldon


Our work focuses on enhancing the understanding of the AWGN broadcast channel in the finite blocklength regime. Through utilization of both a successive power-shell superposition coding scheme (a form of Non Orthogonal Multiple Access (NOMA)) and rate splitting, the largest known (to the authors) second order achievable rate region for the finite blocklength AWGN broadcast channel can be shown. This is in contrast to capacity analysis where rate splitting is not a necessary component.

Our work looks at both global and per-user error constrained versions of the problem. The global error constraint formulation is a required expected reliability for transmission to all users whereas the per-user error constraint requires transmission to each user to meet individual expected reliability requirements. Designing for low latency and high reliability networks (see URLLC) will require knowledge of the reliability requirements of users to maximize the network’s capacity. As an example, for users with a significant difference in required reliability the standard ordering of superposition coding used to achieve capacity for the AWGN broadcast channel can be outperformed by a reverse ordering, The largest region can be achieved via a construction that places messages for the “strong” user as the cloud center.