| In wireless communication systems, the network keeps track of a user’s location through an up-to-date user profile stored in various databases. A user profile contains not only a user’s current location information, but also service information, such as billing and authentication. The coverage area of an access network is divided into registration areas (RAs), and each RA is associated with a location database. The two basic operations in mobility management are location update and location lookup. When a user moves across the boundaries of these RAs, the network updates his location information in the pertinent databases. When a caller places a call using the callee’s identification, the network queries the relevant database(s) to obtain the current location and other service information of the callee.
The performance of mobility management can be further enhanced by using replicas of user profiles which may be kept at various locations. Replication techniques make profile information more readily available, thus reducing lookup cost and latency, but to keep these replicas consistent and fresh, they must be updated whenever the user profile is updated. The principle of replication is to replicate if the benefit of replication is greater than its overhead. The difficulty, however, lies in accurately measuring the benefit and overhead.
Much of the previous work on replication for mobility management was threshold-based, where the benefit and overhead of replication are simply approximated and thresholds are introduced to allow some error margin in deciding where to replicate. Because of their dependency on thresholds and traffic statistics, such threshold-based algorithms not only evade performance analysis but also improvement. |
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RF Microelectronics (Communications Engineering and Emerging Technologies Series)The annual worldwide sales of cellular phones has exceeded $2.5B. With 4.5 million customers, home satellite networks comprise a $2.5B industry. The global positioning system is expected to become a $5B market by the year 2000. In Europe, the sales of equipment and services for mobile communications will reach $30B by 1998. The statistics are... | | The Method of Moments in ElectromagneticsResponding to the need for a clear, up-to-date introduction to the field, The Method of Moments in Electromagnetics explores surface integral equations in electromagnetics and presents their numerical solution using the method of moments (MOM) technique. It provides the numerical implementation aspects at a nuts-and-bolts level... | | Agile Processes in Software Engineering and Extreme Programming: 12th International Conference, XP 2011, Madrid, Spain, May 10-13, 2011, Proceedings (Lecture Notes in Business Information Processing)
This book contains the refereed proceedings of the 12th International Conference on Agile Software Development, XP 2011, held in Madrid, Spain, in May 2011. The year 2011 marked the 10th anniversary of the Agile Manifesto. In this spirit, the XP conference continued its fine tradition of promoting agility by disseminating new research results... |
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