Improving the efficiency of presence service in IMS by JSON

In the recent decade, VOIP and multimedia service through mobile devices are the major trend in the mobile network because of the pervasive handy devices and more advanced cellular network deployed in the world. The next generation network (NGN) solution - IP Multimedia Subsystem (IMS) has great potential to provide a variety of multimedia services. However, the current IMS clients are developed separately based on different operating system (OS). The web based service-oriented architecture can effectively overcome the issue. Adopting the web-based IMS client, we deployed a gateway between IMS clients and the IMS network. Users can access IMS services with any device equipped a web browser that supports WebRTC. Since more and more services exploit the presence service to retrieve and republish users´ information, that would generate a large number of messages. Instead of using XML format to exchange the presence data in presence service, we adopt JSON which is more compact and lightweight format to reduce the message transmission time. We evaluate the system with above two different data formats in a real environment. The result shows that adopting JSON could effectively reduce approximately 54% message transmission time.