| Summary: | 碩士 === 國立交通大學 === 網路工程研究所 === 97 === IP Multimedia Core Network Subsystem (IMS) provides presence service for Universal Mobile Telecommunications System (UMTS). In IMS, the presence server is responsible for notifying an authorized watcher of the updated presence information. If the updates occur more frequently than the accesses of the watcher, the presence server will generate many unnecessary notifications. In this thesis, we implemented an instant messaging and presence service system. In our implementation, we use a weakly consistent scheme (called delayed update) to reduce the notification traffic. In this scheme, a delayed timer is defined to control the notification rate. We propose an analytic model and simulation experiments to investigate the performance of delayed update. The study indicates that delayed update can effectively reduce the notification traffic without significantly degrading the valid access probability.
|
|---|
