Processing transitive nearest-neighbor queries in multi-channel access environments

Abstract

Wireless broadcast is an efficient way for information dissemination due to its good scalability [10]. Existing works typically assume mobile devices, such as cell phones and PDAs, can access only one channel at a time. In this paper, we consider a scenario of near future where a mobile device has the ability to process queries using information simultaneously received from multiple channels. We focus on the query processing of the transitive nearest neighbor (TNN) search [19]. Two TNN algorithms developed for a single broadcast channel environment are adapted to our new broadcast enviroment. Based on the obtained insights, we propose two new algorithms, namely Double-NN-Search and Hybrid-NN-Search algorithms. Further, we develop an optimization technique, called approximate-NN (ANN), to reduce the energy consumption in mobile devices. Finally, we conduct a comprehensive set of experiments to validate our proposals. The result shows that our new algorithms provide a better performance than the existing ones and the optimization technique efficiently reduces energy consumption.

A Novel Hash-Based Streaming Scheme for Energy Efficient Full-Text Search in Wireless Data Broadcast

“…Traditional full-text search techniques cannot not be adopted directly because of this difference. On the other hand, since existing index techniques for wireless data broadcast [10][17] [8] [19] [20] are mainly based on predefined structured data with key attributes, they also cannot be directly applied for full-text search which uses arbitrary words as search keys. Therefore, new design of indexing schemes are needed to facilitate full-text search in order to ensure both time efficiency and energy efficiency.…”