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DYNAMIC CHANNEL ALLOCATION AND BROADCAST DISK ORGANIZATION FOR WIRELESS INFORMATION DISSEMINATION
DU, XIAOMING

2001, MS, University of Cincinnati, Engineering : Computer Science.
Mobile computing has gained increasing attention recently as a variety of mobile terminals and convenient wireless connection becomes available. One of the major applications of mobile computing is information dissemination. The three fundamental methods of providing information on wireless communication channels are push, pull and hybrid push-pull. In a hybrid push-pull environment, the data of most interest is broadcast in the form of a broadcast disk, and the rest of the data is pulled from the server via explicit client requests. To achieve efficient data dissemination, the mobile server dynamically collects users’ query access patterns and allocates data in broadcast disks. However, few studies have been conducted in the area of channel allocation and broadcast disk organization that considerate dynamic access pattern collection and utilization. In this study, we use a bit vector technique to represent mobile users’ access patterns. We introduce a timestamp and a modification indicator to increase the accuracy of using bit vector technology. Algorithms for collecting access patterns are proposed and studied here. Algorithms for determining the optimal channel allocation and broadcast disk organization given a set of access patterns are proposed. The optimal allocation algorithm searches exhaustively for the optimal solution while the heuristic algorithm searches for a solution by finding the optimal number of broadcast channels first and then organizing the data pages on those channels. We also propose and investigate an algorithm for incremental broadcast disk reorganization. Performance studies are conducted using average access probe-wait time as a criterion. Performance studies indicate that the proposed algorithms always outperform the existing flat approach in channel allocation and broadcast disk organization. When the heuristic approach is compared with the optimal approach, experimental results demonstrate that no significant performance differences are observed between the two methods. We also study the performance of the proposed algorithms by varying different system parameter settings such as request rate, data page size, number of channels and the size of database. Experimental results show that in both approaches, the optimal allocation algorithm and heuristic algorithm, the channel allocation adapts to the request rate changes in order to maintain the best performance. That is, when the mobile users’ request rate is high enough, the dynamic channel allocation methods wisely adjusts its allocation method to be close to pure push methods so that the average access probe-wait time remains constant and the best performance is maintained. Increases in either data page size or database size results in longer access waiting times. The effectiveness of algorithm for incremental broadcast disk reorganization is studied as well. The resulting channel allocation and data page organizations are very close to those obtained by applying either the optimal allocation algorithm or the heuristic algorithm to create a new generation of broadcast disks.
Dr. Karen C. Davis (Advisor)
115 p.

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DU, X. (2001). DYNAMIC CHANNEL ALLOCATION AND BROADCAST DISK ORGANIZATION FOR WIRELESS INFORMATION DISSEMINATION. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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DU, XIAOMING. "DYNAMIC CHANNEL ALLOCATION AND BROADCAST DISK ORGANIZATION FOR WIRELESS INFORMATION DISSEMINATION." Electronic Thesis or Dissertation. University of Cincinnati, 2001. OhioLINK Electronic Theses and Dissertations Center. 11 Dec 2017.

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DU, XIAOMING "DYNAMIC CHANNEL ALLOCATION AND BROADCAST DISK ORGANIZATION FOR WIRELESS INFORMATION DISSEMINATION." Electronic Thesis or Dissertation. University of Cincinnati, 2001. https://etd.ohiolink.edu/

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