Scheduling data items with time constraint in ubiquitous computing environments

There are many situations in which we need to incorporate real-time constraints in broadcasting systems for mobile environments. In this paper, we study broadcast scheduling strategies for push-based broadcast with timing constraints in the form of deadlines. Unlike previously proposed scheduling algorithms for broadcast systems which aim to minimize the mean access time, our goal is to identify scheduling algorithms for broadcast systems that ensure requests meet their deadlines. We present a study of the performance of traditional real-time strategies and mobile broadcasting strategies, and demonstrate that traditional real-time algorithms do not always perform the best in a mobile environment. We propose a multichannel model based on push-based real-time broadcast system and also provide an efficient scheduling algorithm, called dynamic adjustment with time constraint (DATC), which is designed for timely delivery of data to mobile clients.