Two-Tier Air Indexing for On-Demand XML Data Broadcast

XML data broadcast is an efficient way to disseminate semi-structured information in wireless mobile environments. Air indexing is the common method to improve the access time, and reduce the energy consumption in a broadcast system. In this paper, the authors propose a novel two-tier air indexing method that provides an overall picture of the document set in the server which is necessary for XML data retrieving in on-demand mode. The efficiency of their indexing method is contributed by two distinct advantages. The proposed pruning technique and the two-tier structure significantly reduce the index size. The two-tier structure enables efficient access protocol at the client which can further reduce the tuning time during the index look up. Simulation experiments show the benefits of their indexing methods.