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UBC Theses and Dissertations

Distributed architectures and databases for personal communications networks and services Ng, Leslie J.


The objective of Personal Communications Services (PCS) is to enable subscribers to establish or receive calls at any user-network access point, independent of geographic location. A hierarchical, distributed database architecture has been developed to perform those mobility management functions required for PCS. This database architecture is developed in the context of a distributed microcellular network architecture based on the IEEE 802.6 Metropolitan Area Network (MAN). Several access MANs are inter-networked via a backbone MAN; these backbone MANs are themselves interconnected to serve an entire metropolitan area (MA). The proposed database architecture can also be applied to other network architectures, such as those based on Asynchronous Transfer Mode (ATM) switches. The physical and logical database structure and contents have been defined. The protocols necessary to perform the basic mobility management functions of subscriber location at call setup as well as tracking of a roaming subscriber have been developed. Two subscriber location algorithms have been proposed. The signalling traffic and database transaction rates required to support subscriber location and tracking are calculated. The worst-case database transaction rate of approximately 2300 transactions per second occurs at the highest level databases. The worst case signalling traffic overhead is approximately 500 kbps on the access MAN and 2.5 Mbps on the backbone MAN. Queueing theory has been applied to determine the means and standard deviations of the database processing times for call setup. The worst case expected time for the ripple search is under 20 ms. The worst case expected time for the directory search is bounded above by 40 msor 10 ms, depending on the database transaction capacity. The approximate database sizes are estimated at 14.5, 7, and 36.8 Mbytes for the access MAN, backbone MAN and MA level databases respectively. A similar analysis is completed for a centralized database architecture, where lower level access and backbone MAN databases are eliminated and mobility management functions are performed by the centralized high level Metropolitan Area databases. The worst case transaction rate is over 7000 persecond. The worst case signalling rate is approximately 6 Mbps on both the access and backbone MANs.The worst case expected database processing time is under 10 ms, but is only achievable with databases having a much higher transaction capacity than those considered for the distributed architecture. The central MA database size is estimated to be approximately 476 Mbytes. By utilizing the localized distribution of calls to spread query traffic among different database sites and levels, our distributed database architecture is expected to be responsive and flexible as PCS demand increases. Subscriber update traffic is distributed, with detailed information stored close to subscriber locations.

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