On causal scheduling of multiclass traffic with deadlines

Causal scheduling-dropping policies for multiclass traffic with deadlines are considered. Packets with deadlines and class labels arrive in discrete time and are either scheduled by their deadlines or dropped on or possibly before their deadlines. Emphasis is on the case that there are two classes of traffic, and on causal policies which at any given time base decisions on arrivals up to that time. First the causal scheduling-dropping policies that maximize total throughput are identified. Then those scheduling dropping policies with the greatest throughput for the high priority class, subject to being causal and maximizing total throughput, are identified.