Query-grouping based scheduling algorithm for on-demand XML data broadcast

Data broadcast is an efficient way for information dissemination in wireless mobile environments. On-demand XML data broadcast is a rising research issue in this area. How to schedule the XML data on wireless channel is critical for this issue. When scheduling the XML data, previous work proposed to satisfy the user queries which request fewer branches of the broadcasted XML documents first. However, the user queries usually request different parts of the same XML document. Many queries have to download redundant XML data to get the requested XML data when the requested XML document is broadcasted as a complete document. Based on this observation, in this paper, we propose to categorize the user queries into different groups and then schedule the XML data according to the grouping results. Our query-grouping based scheduling algorithm eliminates redundant XML data in the broadcasted XML documents for each query group. Experiments show that our algorithm provides significantly better performance and scalability when compared with existing scheduling algorithms.