FlexSched : a Flexible Data Schedule Generator for Multi-Channel Broadcast Systems
André Seifert, Jen-Jou Hung · KOPS (University of Konstanz) · 2005
Abstract. This paper is concerned with the issue of building efficient and flexible data broadcast programs for a multiple physical channel environment. The goal of our work has been twofold: (a) to minimize the cost of building the broadcast program and (b) to minimize the average access latency for data requests of mo-bile clients. To achieve both goals, a highly flexible scheduler, called FlexSched, is proposed, taking a divide-and-conquer approach to solve the data scheduling problem. To determine the optimal allocation of the data to the existing physical channels, FlexSched initially makes a single scan over the vector of access prob-abilities of the data items and assigns them to the broadcast channels based on the square-root formula of optimal bandwidth usage, i.e., data items are mapped to channels in proportion to the square-root of their access probabilities. For each physical channel a skewed broadcast schedule is then produced by first assigning each data item to its own data group and then iteratively merging neighboring data groups so that the overall average access time of the initial schedule is con-tinously reduced. The merging procedure terminates if there are no more neigh-