Bringing location based services to IP multimedia subsystem

As a result of the evolution of computer and networking technologies, the third generation partnership project (3GPP) has proposed the IP multimedia subsystem (IMS) as a key element in the UMTS architecture supporting multimedia services in the packet switched domain. Extending the IMS with support for location based services (LBS) enables enhanced services and offer new revenues to the system. Connecting the IMS core network with a real positioning system providing support for LBS is an open issue. This paper addresses this issue and presents the design and implementation of an IMS location server (ILS) connecting the IMS with a positioning system. From the IMS perspective, ILS serves as a service enabler for LBS in the mentioned subsystem. In order to demonstrate proof-of-concept in enhancing IMS-based services, a location-aware push-to-talk (LaPoC) prototype service has been developed. The service has been integrated with the Ericsson mobile positioning system (MPS). This paper also gives the results of performance measurements including traffic load analysis and session establishment time