INTRODUCTION
A mobile virtual reality service (VRS) will make the presence and presentation of the sounds and sights of an actual physical environment virtually available everywhere in real time through the use of mobile telecommunication devices and networks. Furthermore, the VRS is the conversion of a physical system into its digital representation in a three-dimension (3D) multimedia format. This paper addresses one aspect of the notion of bringing an actual multimedia environment to its virtual presence everywhere in real time .An international telecommunication union (ITC) recommendation document, containing ITUâ„¢s visions on mostly forward-looking and innovative services and network capabilities, addresses the capability needed in a telecommunication system to allow mobile access to real-time sights and sounds of an actual physical environment in the contest and forms of a VRS episode .
Presently, the availability of a VRS is limited to fixed-access phenomena in non-real time , for example , entertainment machines and various simulations equipment. There are also some limited fixed-access and real-time services that require low data transmission rates, such as net meetings. In the latter case, a user can experience a limited real-life environment as opposed to the former case of a non-real-life computer-generated environment. These existing virtual reality services do not allow user control in viewing 3D environments, and they are generally limited to viewing images on a monitor in two dimensions. The VRS-capable systems, however, will allow rather 3D representations of remote real-life environments. For instance, a passenger in a train or in a car could become a participant in a conference call in a 3D environment or become virtually present among the audience in a concert hall or sports stadium viewing a live concert or event.
There are a few obstacles and bottlenecks to the realization of such VRS-capable systems. The development of real-time mobile 3Denvironments requires:
¢ Super-high-speed data transmission rate capability for data streaming.
¢ Highly complex and sophisticated user equipment for user access, and
¢ An advanced signaling and controlling data network.
The advanced signaling and controlling data network is for initiating, establishing, maintaining, and terminating VRS episodes. Exponential increases in data transmission rates and innovative advances in development of terminal equipment are paying the way for the provision of the VRS and the creation of VRS episodes in the near future. Furthermore,the realization of the VRS assumes that the high-tech industry will deliver super high data rate(SHDR) transmission equipment offering a transmission speed of equal to or higher than one gigabit per second to a single user or end point . The anticipated demand for data transmission speed in 2005 will be higher than 20 M/s, upgraded from todayâ„¢s third-generation planned 2 Mb/s. the transmission speed requirements for the so-called fourth generation systems in 2007 are expected to reach near 100 Mb/s. At these rates, telecommunication equipment should be able to transmit, transport, and receive sights and sounds of real-life environment for establishing a VRS episode.
The development of the core signaling and controlling network and its associated software platforms for VRS episode control and for terminal and end-user equipment mobility management is viewed as a major challenge in terms of its control logic and its application programming interfaces for provisioning of the VRS. This paper addresses the core network sub-system for VRS episode control. Several VRS use cases are presented first, and major issues for realization of the VRS are identified. The paper then proposes a solution scheme for the core network signaling and the VRS episode control. The final section of the paper describes an implementation scenario along with an example of signaling flows for establishing and controlling episodes.
PROBLEM STATEMENT
From a users perspective, the VRS is defined as the experience of viewing an object in its 3D environment and sensing its sound with its natural and real-world quality. By limiting the VRS to sight and sound, it is meant to disclaim creation of any other aspects of an actual physical environment, for example, smell of a flower or taste of a food. A few examples of the VRS is listed below:
¢ A virtual conference session depicting to every participant the presences of others in a virtual conference room with projector screen, drawing board, and so on.
¢ A virtual movie theaters where a user can view movies with the same feel as being in a movie theater.
¢ A virtual hospital operation room (OR) where a surgeon can remotely perform an actual operation and/or provide training to assistant surgeons and interns by showing and/or performing actual procedures.
¢ A virtual concert hall where a conductor can have the virtual presence of all, or a selective number of instruments players participating from all over the world for a rehearsal or actual performance.
¢ A virtual house, shop, or storage facility where a user can do a security check, identify product availability, or determine inventory levels of various items, respectively.
¢ A virtual command center for navigating an aircraft, driving a train, or operating a motor vehicle where the virtual environment is created for the cockpit, the locomotive, or the driver™s seat respectively.
¢ From a network operator™s perspective, the provision of the VRS is the conversion of the sights and sound of an actual physical system into their virtual representation. For each required case and application, the development of the software platforms for the control and the management of the VRS and in terms of its control logic and application-programming interface is a major challenge. The VRS will include both terminal and personal mobility. It could be a set up in a limousine, hotel, airport, home or office. Depending on the type and complexity of the actual system, the estimate for required data transmission rates varies from a minimum of tens of Megabits to a few Gigabits per user or user equipment.
Currently, the availability of the VRS is limited to fixed application s in noon-real time, for example, entertainment machines and flight simulators. Some limited feature- fixed real-time services such as video-conferencing and net meetings, which require low data transmission rates, are also offered. However, the mobile, wireless, and real-time accessed sights and their virtual reality presence are still dreams. Major obstacles and bottlenecks to the achievement of such an ambitious goal include:
¢ Lack of VRS-capable user terminal equipment.
¢ Inadequate data transmission rates over the air, and
¢ Absence of efficient and suitable signaling and controlling network elements for initialing, establishing, maintaining and terminating mobile VRS episode.
The section below addresses the signaling and controlling part of the solution, and proposes a VRS provisioning solution scheme by focusing on the core signaling and controlling network including a high level view of the signaling network architecture and its controlling functional entities. An under lying assumption for this proposed solution is that the high-tech industry will deliver the required SHDR radio transmission capability along with VRS-capable equipment.
Expectedly, the ongoing development activities on the optical capacity problems and the tripling antenna project will find their way into mobile telecommunication equipments in the near future and will alleviate some of the critical bandwidth problem. The requirements for mobile terminal equipment and the radio access network to meet the spectrum and data transmission speed requirements are beyond this section. Furthermore, this services capability may also be restricted in terms of mobility. In its early phases of development, the wireless SHDR transmission capability may be limited to slow-moving terminal equipment. Increases in the data rate in the post-IMT-2000 era could expectedly reach 100Mb/s for indoor access. The proposed solution describes a mobile VRS environment in general and its core network for signaling and controlling of a VRS episode in specific. It presents an overview of the VRS architecture and describes the various entities to perform the task of VRS provisioning .The VRS functional architecture is proposed in full harmony with preceding generations of all-IP multimedia core network functional architectures currently under study and development in the third- Generation partnership project.
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