Pervasive and Mobile Data Access

Overview

Efficient data access for mobile and pervasive computing is a field of increasing importance for a wide range of mobile businesses and applications. It will be a key technology as ubiquitous wireless connectivity becomes a reality. We are one of the first few pioneers who started research in this area. We have been studying several fundamental issues in data and resource management of mobile computing systems, including: indexing and caching for reducing power consumption and increasing data access efficiency, data allocation for multiple wireless communication channels, cache invalidation and replacement policy for wireless data dissemination, and performance modeling and evaluation for wireless data access.

Many of the techniques we developed have been well received in the field and inspired a number of follow-up works. The signature schemes we developed for wireless information filtering [DAPD'96, WINET'99] have become a classical energy efficient indexing technique for wireless data broadcast services. We also analyzed the problems of wireless channel allocation for data dissemination via on-demand and broadcast channels and developed a dynamic channel allocation algorithm to optimize the system performance [ICDCS'98, MONET'99]. By integrating various related techniques proposed in our studies, we developed a hierarchical wireless data dissemination system which has brought a lot of insights to to the research of data dissemination systems [MobiCom'99]. We also developed indexing techniques to support energy-efficient queries specified based on multiple attributes [ICDE'00, MONET'01] and mobile caching techniques for on-demand data broadcast systems [CIKM'00, ICPP'01, TKDE'04]. Moreover, We have recently developed a novel parameterized index, called the exponential index, which allows the system administrators to use two tuning knobs (i.e., index base and chunk size), to optimize the access latency with the tuning time bounded by a given limit, and vice versa [MobiSys'04, TKDE]. These research results could be used in wireless data services such as MSN Direct and StarBand and may have practical impact on on-going work in standard bodies (e.g., the Broadcast and Multicast Service for CDMA2000 Wireless IP network, being developed by the Third Generation Partnership Project 2 (http://www.3gpp2.org/).

While many of of our previous work focused on system issues, we have recently paying attention to various application requirements such as timeliness and security. We have developed a novel on-demand broadcast scheduling algorithm by taking into consideration the urgency of requests and the number of outstanding requests [TPDS]. In this study, theoretical bound of request drop rate when the request arrival rate rises towards infinity is derived. We have also investigated the tradeoff between performance and confidentiality of signature-based air indexes in terms of their relationships to false drop and false guess probabilities of the signatures [CIKM'05]. This is the first time the issue of confidentiality loss in air indexing has been identified and discussed in the literature. Additionally, an efficient key management scheme, KTR, has been developed to for access control of broadcast data [Mobiquitous'05]. KTR allows multiple broadcast programs share a single key tree such that the users subscribing these programs need to hold only a small number of keys. In this scheme, rekey cost is minimized by identifying the minimum set of keys that must be changed to ensure broadcast security. This is also the first time a key management scheme being proposed for wireless data broadcast.

Current Members

Collaborators

Publication

1. C.K. Lee, W.-C. Lee, and S. Madria, Pervasive Data Access in Wireless and Mobile Computing Environments, Wireless Communication and Mobile Computing Journal, to appear.

2. J. Xu, W.-C. Lee, X. Tang, Q. Gao, and S. Li, An Error-Resilient and Tunable Distributed Indexing Scheme for Wireless Data Broadcast, IEEE Transactions on Knowledge and Data Engineering (TKDE), to appear. [pdf]

3. J. Xu, X. Tang, and W.-C. Lee, On Scheduling Time-Critical On-Demand Broadcast, IEEE Transaction on Distributed and Parallel Systems, Volume 17, Issue 1, Jan. 2006, pp. 3-14. [pdf]

4. Q. Tan, W.-C. Lee, B. Zheng, P. Liu, and D.L. Lee, Balancing Performance and Confidentiality in Air Index, ACM Fourteenth Conference on Information and Knowledge Management (CIKM'05), Breman, Germany, October 2005, to appear. [pdf]

5. J. Xu, W.-C. Lee, and X. Tang, Exponential Index: A Parameterized Distributed Indexing Scheme for Data on Air, the Second International Conference on Mobile Systems, Applications, and Services (Mobisys'04), Boston, MA, June 6-9, 2004, pp. 153-164. [pdf]

6. J. Xu, W.-C. Lee, and J. Liu, Scheduling Web Requests in Broadcast Environments, the thirteenth International World Wide Web Conference (WWW'04), New York, NY, May 17-22, 2004, pp. 280-281. (Poster)

7. J. Xu, Q. Hu, W.-C. Lee, and D.L. Lee, Performance Evaluation of an Optimal Cache Replacement Policy for Wireless Data Dissemination under Cache Consistency, IEEE Transaction on Knowledge and Data Engineering (TKDE), Volume 16, No. 1, January, 2004, pp. 125-139. [pdf]

8. J. Lee, W.-C. Lee, C.-P. Liu, A.-T. Wang, and C. Chang, Monte Carlo Methods on Customer Retrial Calls in Communication Networks, Chung Yuan Journal, Vol. 31, No. 3, September, 2003, pp. 151-159.

9. J. Xu, W.-C. Lee, D.L. Lee, and Q. Hu, Data Broadcast, Handbook of Wireless Networks and Mobile Computing, edited by I. Stojmenovic, John Wiley & Sons, 2002, ISBN 0-471-41902-8, pp. 243-265.

10. W.-C. Lee and D.L. Lee, Models and Infrastructures for Pervasive Computing, NSF Workshop on Context-Aware Mobile Database Management (CAMM), Providence, Rhode Island, January 24-25, 2002. [pdf]

11. J. Xu, Q. Hu, W.-C. Lee, and D.L. Lee, An Optimal Cache Replacement Policy for Wireless Data Dissemination under Strong Cache Consistency, International Conference on Parallel Processing (ICPP'01), Valencia, Spain, September 3-7, 2001, pp. 267-274. [pdf]

12. Q. Hu, W.-C. Lee, and D.L. Lee, Indexing Techniques for Power Management in Multi-Attribute Data Broadcast, ACM Mobile Networks and Applications Journal (MONET): Special Issue on Management of Mobility in Distributed Systems, Volume 6, No. 2, March 2001, pp. 185-197. [pdf]

13. Q. Hu, W.-C. Lee, and D.L. Lee, A Hybrid Index Techniques for Power Efficient Data Broadcast, Distributed and Parallel Databases, Volume 9, No. 2, March 2001, pp. 151-177. [pdf]

14. Q. Hu, W.-C. Lee, and D.L. Lee, Power Conserving and Access Efficient Indexes for Wireless Computing, Information Organization and Databases, edited by K. Tanaka, S. Ghandeharizadeh, and Y. Kambayashi, Kluwer Academic Publishers, Boston, MA, 2000, pp. 249-264.

15. J. Xu, Q. Hu, W.-C. Lee, and D.L. Lee, SAIU: An Efficient Cache Replacement Policy for Wireless On-demand Broadcasts, the Ninth ACM International Conference on Information and Knowledge Management (CIKM’00), McLean, VA, Nov. 6-11, 2000, pp. 46-53. [pdf]

16. Q. Hu, W.-C. Lee, and D.L. Lee, Power Conservative Multi-Attribute Queries on Data Broadcast, IEEE International Conference on Data Engineering (ICDE'00), San Diego. Feb. 2000, pp. 157-166. [pdf]

17. W.-C. Lee, J. Lee and K. Huff, On Simulation Modeling of Information Dissemination Systems in Mobile environments, ACM/IEEE International Conference on Mobile Data Access (MDA’99), Hong Kong, Dec. 1999, pp. 45-57. [pdf]

18. Q. Hu, W.-C. Lee, and D.L. Lee, Indexing Techniques for Wireless Data Broadcast Under Data Clustering and Scheduling, ACM International Conference on Information and Knowledge Management (CIKM'99), Kansas City, Missouri, Nov. 1999, pp. 351-358. [pdf]

19. Q. Hu, D.L. Lee, and W.-C. Lee, Performance Evaluation of a Wireless Hierarchical Data Dissemination System, ACM/IEEE International Conference on Mobile Computing and Networking (Mobicom'99), Seattle, Washington, August 1999, pp. 163-173. [pdf]

20. W.-C. Lee, Q. Hu, and D.L. Lee, A Study of Channel Allocation Methods for Data Dissemination in Mobile Computing Environments, ACM Mobile Networks and Applications Journal (MONET): Special Issue on Resource Management in Wireless Network, Volume 4, No. 2, 1999, pp. 117-129. [pdf]

21. W.-C. Lee and D.L. Lee, Signature Caching Techniques for Information Filtering in Mobile Environments, ACM Wireless Networks Journal (WINET), Volume 5, No. 1, January 1999, pp. 57-67. [pdf]

22. Q. Hu, W.-C. Lee, and D.L. Lee, Dynamic Data Delivery in Wireless Communication Environments, International Workshop on Mobile Data Access, Singapore, Nov. 1998, pp. 218-229.

23. D.L. Lee, Q. Hu, and W.-C. Lee, Indexing Techniques for Data Broadcast on Wireless Channel, the Fifth International Conference of Foundations of Data Organization (FODO'98), Kobe, Japan, Nov. 1998, pp. 175-182. [pdf]

24. Q. Hu, D.L. Lee, and W.-C. Lee, Optimal Channel Allocation for Data Dissemination in Mobile Computing Environments, IEEE Conference on Distributed Computing Systems (ICDCS'98), Amsterdam, Netherlands, May 1998, pp. 480-487. [pdf]

25. Q. Hu, W.-C. Lee, and D.L. Lee, A Comparison of Index Methods for Data Broadcast on the Air, International Conference on Information Networking (ICOIN'98), Tokyo, Japan, Jan. 1998, pp. 656-659.

26. W.-C. Lee, Q. Hu, and D.L. Lee, Channel Allocation Methods for Data Dissemination in Mobile Environments, the Sixth Symposium on High Performance Distributed Computing (HPDC'97), Portland, Oregon, August 5-8, 1997, pp. 274-281. [pdf]

27. W.-C. Lee, and D.L. Lee, Using Signature Techniques for Information Filtering in Wireless and Mobile Environments, Distributed and Parallel Databases: Special Issue on Database and Mobile Computing, Vol. 4, No. 3, July 1996, pp. 205-227. (Also appears as a chapter in the book, Databases and Mobile Computing, edited by D. Barbara, R. Jain and N. Krishnakumar, Kluwer Academic Publishers, 1996, ISBN: 0792397495. ) [pdf]

28. W.-C. Lee, and D.L. Lee, On Signature Caching of Wireless Broadcast and Filtering Services, the Second International Mobile Computing Conference, Hsinchu, Taiwan, March 25-27, 1996, pp.15-24.

29. W.-C. Lee, and D.L. Lee, Information Filtering in Wireless and Mobile Environments, IEEE International Phoenix Conference on Computers and Communications (IPCCC'96), Phoenix, Arizona, March 27-29, 1996, pp. 508-514. [pdf]