Energy-Efficient Tree-Based Indexing Schemes for Information Retrieval in Wireless Data Broadcast

Abstract

Mobile computing can be equipped with wireless devices to allow users retrieving information from anywhere at anytime. Recently, wireless data broadcast becomes a popular data dissemination method, especially for broadcasting public information to a large number of mobile subscribers at the same time. Access Latency and Tuning Time are two main criteria to evaluate the performance of a data broadcast system. Indexing can dramatically reduce tuning time by guiding clients to turn into doze mode while waiting for the data to arrive. B+-Tree Distributed Index Scheme (BTD) is a popular index scheme for wireless data broadcast, which has been extended by many research works. Among traditional index structures, alphabetic Huffman tree is another important tree-based index technique with the advantage of taking data's access frequency into consideration. In this paper, we are trying to answer one question: can alphabetic Huffman tree replace B+-tree and provide better performance? To answer this question, we propose a novel Huffman-Tree based Distributed Index Scheme (HTD) and compare its performance with BTD based on a uniform communication environment. The performances of HTD and BTD are analyzed both theoretically and empirically. With the analysis result, we conclude that HTD outperforms BTD and can replace BTD in most existing wireless data broadcast system.