Database Cache Management Algorithms of a Timing Constrained Database System in Mobile Computing Environments

Yuji WADA  Tadanori MIZUNO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E79-A   No.7   pp.1027-1033
Publication Date: 1996/07/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Multi-dimensional Mobile Informatin Network)
databases,  mobile computing,  mobile communication,  modeling and simulation,  software system,  

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In this paper, we propose a timing constrained database system which accesses a database at a host computer via a mobile support server with a wireless portable computer running in mobile computing environments, so that we can provide seamless database access between a communication cell and the host computer even if the user of the portable computer moves from one communication cell to another. Then, we also provide some new kind of database cache algorihm, such as all-cell-cache, neighbour-cell-cache, 1-cell-skip-cache, 2-cell-skip-cache and 3-cell-skip-cache methods, each of which manages the data downloading and uploading among the host database and some cell databases at the mobile support servers so as to minimize the database access fault probability when the user moves from one communication cell to another. And, we show the averaged database access time and the averaged database cache hit ratio which are computed by simulating each of the above database cache algorithms with random variables generation method. Finally, we conclude that each above cache alogorithm is advantageous to the database in mobile computineg einvironments.