Scheduling Data Broadcast

Data broadcast is an effective method of information dissemination in satellite networks. Communications in satellite networks are usually asymmetric — the downstream communication capacity, from information server to clients, is much greater than the upstream communication capacity, from clients to server. It is not efficient (and sometimes not possible) for clients to send explicit requests to the server and for the server to serve requests individually. In data broadcast approach, the server broadcasts data items periodically over a broadcast channel that all clients listen to, serving a large number of clients demanding for same information simultaneously. One challenge in implementing this solution is to determine the broadcast schedule, such that the clients receive the best quality of service.In this chapter, we study the optimal broadcast scheduling problem in a pure push data broadcast system. Our study is different from other researchers in that we assume both persistent user model and impatient user model. For each model, we define different performance metrics to address the most important user concerns. The properties of schedules that optimize each metric are derived through theoretical analysis. Based on theoretical results, we propose a heuristic algorithm for producing near-optimal schedules on-line. Performance evaluation results are also presented.