Central Concerns and Questions

We are interested in developing mechanisms for users to retrieve location-dependent data from wireless broadcast channels efficiently (i.e., with less energy consumption and shorter access latency).

Emerging Ideas and Initiatives

The data broadcast on air is only available to users when it is broadcast. In another words, wireless broadcast system does not support random access like traditional database environments. Existing indexing structures designed for traditional database environments allow random access and backtracking to speed up the search. As a result, existing indexes cannot guarantee the efficiency of the search for wireless systems. In other words, wireless channel is error-prone, and the dissemination approaches have to take the frequent packet loss into consideration, and should be able to support immediate resume once packet loss happens.

Selected Publications

[[1] Baihua Zheng, Wang-chien Lee, Ken C. K. Lee, Dik Lun Lee and Min Shao: A Distributed Spatial Index for Error-Prone Wireless Data Broadcast. VLDB Journal, 18(4): 959-986, 2009.

[2] Yunjun Gao, Baihua Zheng, Gencai Chen, Wang-chien Lee, Ken C. K. Lee and Qing Li: On Efficient Visible Reverse k-Nearest Neighbor Query Processing in Spatial Databases. IEEE Trans. Knowledge and Data Engineering (TKDE), 21(9): 1314-1327, 2009

[3] Yunjun Gao, Baihua Zheng, Gencai Chen, and Qing Li: On Efficient Mutual Nearest Neighbor Query Processing in Spatial Databases. Data & Knowledge Engineering (DKE), 68(8): 705-727, 2009

[4] Yunjun Gao, Baihua Zheng, Gencai Chen, and Qing Li: Optimal-Location-Selection Query Processing in Spatial Databases. IEEE Trans. Knowledge and Data Engineering (TKDE), 21(8):1162-1177, 2009

[5] Ken C. K. Lee, Baihua Zheng, and Wang-chien Lee: Ranked Reverse Nearest Neighbor Search. IEEE Trans. on Knowledge and Data Engineering (TKDE), 20(7): 894-910, 2008

[6] Yunjun Gao and Baihua Zheng: Continuous Obstructed Nearest Neighbor Queries in Spatial Databases. Proc. of the ACM Sigmod Conference, June 29- July 02, Providence, Rhode Island, USA : 577-590

[7] Yunjun Gao, Baihua Zheng, Gencai Chen, Wang-Chien Lee, Ken C. K. Lee, and Qing Li: Visible Reverse k-Nearest Neighbor Queries (short paper). Proc. of the 25th International Conference on Data Engineering (ICDE'09), March 29 - April 4, 2009, Shanghai, China

[8] Ken C. K. Lee, Wang-Chien Lee, Hong Va Leong and Baihua Zheng: OPAQUE: Protecting Path Privacy in Directions Search (short paper). Proc. of the 25th International Conference on Data Engineering (ICDE'09), March 29 - April 4, 2009, Shanghai, China

[9] Yunjun Gao, Baihua Zheng, Wang-Chien Lee and Gencai Chen: Continuous Visible Nearest Neighbor Queries. Proc. Of the 12th International Conference on Extending Database Technology (EDBT'09), March 23-26 2009, Saint-Petersburg, Russia : 144-155

[10] Ken C. K. Lee, Wang-Chien Lee, and Baihua Zheng: Fast Object Search on Road Networks. Proc. of the 12th International Conference on Extending Database Technology (EDBT'09), March 23-26 2009, Saint-Petersburg , Russia : 1018-1029

[11] Kyriakos Mouratidis, Yimin Lin, Man Lung Yiu: Preference Queries in Large Multi-Cost Transportation Networks (long paper). Proc. of the 26th International Conference on Data Engineering (ICDE'10) , March 1-6, 2010, Long Beach, California, USA.

Projects, Presentations and Posters

1. Baihua Zheng, OPAQUE: Protecting Path Privacy in Directions Search (presentation at ICDE 2009)
2. Kyriakos Mouratidis, Preference Queries in Multi-Cost Networks (poster at ICDE 2010)