Project Summary

Publications and Products

• Nimisha Garg, Vijay Kumar, and Maggie H. Dunham, "Information Mapping and Indexing in DAYS", 6th International Workshop on Mobility in Databases and Distributed System (MDDS), in conjunction with the 14th International Conference on Database and Expert Systems Applications, September 2003, accepted to appear.
• Zhigang Li, Ming-Tan Sun, Margaret H. Dunham, and Yongqiao Xiao, "Improving the Web Site’s Effectiveness by Considering Each Page’s Temporal Information", The Fourth International Conference on Web-Age Information Management (WAIM), August 2003.
• Yongqiao Xiao, Jenq-Foung Yao, Zhigang Li, and Margaret H. Dunham, "Efficient Data Mining for Maximal Frequent Subtrees", 2003 IEEE International Conference on Data Mining (ICDM), November 2003, accepted to appear.
• Ahmad S. Al-Mogren and Margaret H. Dunham, "Concurrency Control Performance in DAYS", 2003 ACM International Workshop on Data Engineering for Wireless and Mobile Access (MOBIDE), September 2003, accepted to appear.

Project Impact

Goals, Objectives and Targeted Activities

DAYS  has full database and transaction management capability.  For this reasons we have to provide necessary database services such as transaction serialization, database recovery, database access, database query, etc.  Because it is constructed on wireless platform we also develop scheme for efficient channel management, data caching and indexing for faster access.  The following list defines our major goals:

1. Design a broadcast server/mobile station coupled architecture which ensures a global broadcast coverage (as opposed to local).  In this scheme DAYS can be accessed by any geographical location without the
   constraints of cellular architecture of PCS or GSM.
2. Development of a unique concurrency control technique which would allow DAYS to handle consistency preserving execution of user transactions.  It will allow a wireless user the ability to perform a
   transaction by combining a read through the broadcast and write through a special mobile transaction.
3. DAYS will provide techniques to predict mobile user movement and to move a user's data to future predicted broadcast servers prior to his arrival in a broadcast cell.
4. In DAYS, a mobile user must be able to determine what local broadcast channel contains his desired data.  We will investigate several approaches to satisfy this and recommend the best.
5. The contents of these broadcast channels will change depending upon the requirements of the users and also of DAYS.  We will investigate efficient indexing schemes for managing the reorganization of
   broadcast contents and supporting finer granularity information access.
6. It may be necessary to duplicate or replicate broadcast contents to more than one dedicated channel.  This may be decided on demand or for improving availability.  We will investigate schemes for distribution of data in DAYS.

This is collaborative research and the entire project is being investigated under a joint effort.  Iin the paragraphs below we briefly discuss the ongoing work being performed at SMU.

Concurrency Control Technique: We have previously proposed a concurrency control technique, BUC, which facilitates the update of data read from a broadcast.  This approach is a combination of processing algorithms, concurrency control algorithms, and broadcast structure.  In the past year we reported on the results of an analytic performance study which examined the overhead associated with BUC. Our study showed the superiority of the BUC technique by reducing the overhead requirements.  Although the BUC approach and our DAYS architecture can be used independently, their use together provides a solid approach for the design of future wireless broadcast applications.  Note that BUC in combination with DAYS provides an approach whereby all types of transactions from fixed and wireless users may be executed in parallel while still achieving serializability.  In addition, through the use of a backchannel BUC allows users reading data through a broadcast the ability to perform consistent updates at content provider locations.

Data Mining:  Although data mining activities were not included in the original scope of the proposal, at SMU we have been investigating Web usage mining techniques targeted to expanding algorithms for frequent sequence and subtree mining.  Web access is supported by the DAYS architecture.  Due to the limited resources available on mobile devices, Web usage mining will be used to help determine cache and broadcast channel content.  We are beginning to apply these techniques to predict the content of channel broadcast from a universal perspective.

Area Background

While the area of wireless data broadcast has been studied in the past, we are the first to look at how to effectively provide a universal ubiquitous broadcast.  The approach is to primarily support a push based approach for data dissemination.    In addition the use of uplink channels facilitate limited updating and push based requests.

Area References