Abstract (Summary)
Mobile computing is a fast growing research and commercial area. An important application of mobile networks is data dissemination over limited bandwidth channels. There are different modes of data dissemination: push-based, pull-based, or a combination of both. In push-based, the data is broadcast in the form of broadcast disks. In pull-based, a mobile unit sends an uplink query to a central server, the server processes the data and sends the answer on a downlink channel. If the number of uplink queries is large, a lot of channel bandwidth is expended in sending the answers on the downlink channels. In this study, we apply multiquery optimization to batches of pull requests in mobile databases. Materialized views are created that can be used to answer several queries at once. The materialized views are then broadcast on a push-pull channel dedicated for this purpose (answers to multiple pull queries). Each mobile unit receives a short message from the server that contains information about when and for how long to tune to the channel to retrieve the requested information. We compare multiple query processing for pull requests (MQPR) with a basic pull request method (PR) in which each query is handled separately. Appropriate algorithms and formulae are given to calculate the bandwidth usage and the wait time for the mobiles sending the requests. A performance study is conducted by simulating different query loads over a testbed schema. The studies indicate a significant savings in the channel bandwidth usage and also a significant reduction in the wait time in MQPR compared to PR.
Bibliographical Information:


School:University of Cincinnati

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:mobile databases multiquery processing mqp pull request


Date of Publication:01/01/2001

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