Schabanel N. (2000) The Data Broadcast Problem with Preemption. In: Reichel H., Tison S. (eds) STACS 2000. STACS 2000. Lecture Notes in Computer Science, vol 1770. Springer, Berlin, Heidelberg
The data-broadcast problem consists in finding an infinite schedule to broadcast a given set of messages so as to minimize the average response time to clients requesting messages, and the cost of the broadcast. This is an efficient means of disseminating data to clients, designed for environments, such as satellites, cable TV, mobile phones, where there is a much larger capacity from the information source to the clients than in the reverse direction.
Previous work concentrated on scheduling indivisible messages. Here, we studied a generalization of the model where the messages can be preempted. We show that this problem is NP-hard, even in the simple setting where the broadcast costs are zero, and give some practical 2-approximation algorithms for broadcasting messages. We also show that preemption can improve the quality of the broadcast by an arbitrary factor.