Real-time Communication in a Ubiquitous Office Environment
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Combining multiple fixed and mobile terminals to create a real-time communication session can be troublesome. Consider the following scenario: Alice is at work, and wants to place a video call to Tom, who is not currently in his office. Since Alice is requesting a video conversation, Tom steps into the nearest video equipped meeting room. The available system in the room is sensed by his mobile terminal and enables Tom to setup a call between the room system and Alice. The call control remains on his mobile node.This and similar scenarioes raise several issues. Typical challenges include where to log in, where to initiate and terminate a call, and where to control call sessions. Media capabilities found on a mobile terminal is sometimes insufficient, for instance to handle video calls. Ubiquitous computing makes it possible to sense and utilize entities in the environment with minimal effort for the user. High quality video equipment is typically located at fixed locations due to their size. Thus, a Personal Area Network can be utilized to autonomously provide information regarding nearby equipment through distributed Service Discovery. The sensed equipment can be utilized in calls, to provide enhanced media capabilities, when needed.A call between two parties that is setup and controlled by a third party, is referred to as third party call control (3PCC). 3PCC can be facilitated to enable a low capability mobile node with higher capabilities for call setup, when such are sensed. RFC 3725 was used as a guideline for the 3PCC component, and extended the features to allow incoming calls as well as outgoing calls. Another important feature is that core call control is kept on the mobile node. It can be argued that such a system should be compliant with basic SIP (as described in RFC 3261) for all communication across domains. Hence, the system will not put any restrictions on the far end, which is important to ensure interoperability with 3rd party SIP equipment. This feature will also shorten the expected time-to-market for the system, as no standardization is required. The proposed solution consists of two components; a distributed service discovery component that senses nearby call enabled equipment, and a 3PCC component that enables call setup and core call control. The solution is implemented and tested with standardized SIP equipment.