Scheduling on the Gaussian Broadcast Channel with Hard Deadlines

This paper, motivated by mission-critical and latency-constrained traffic, focuses on delivering different messages to various end-users within hard deadlines on the downlink of a wireless system. A novel deadline outage performance criterion is introduced, which accounts for both the violation of the hard deadline by any of the messages as well as for channel decoding errors due to finite block-length. This formulation allows for the study of scheduling policies under a more refined model of the physical layer channel than is usually assumed in the networking literature. Different scheduling polices under hard deadline constraints are proposed, and the corresponding deadline outage probabilities evaluated. The main result is that, to reduce the deadline outage probability, a scheduling policy should cleverly combine time-sharing and concatenate-and-code.