Demands from customers result in improvements to multimedia sharing for the public and private sectors.
A Hungarian army officer checks the voice over Internet protocol connection and video feed during the testing phase of exercise Combined Endeavor 2007. The Internet protocol multimedia subsystem (IMS) is an architecture that will deliver multimedia communications quickly and efficiently.
The new network technology stems from a demand from enterprise and consumer commercial subscribers for more powerful services under tighter budgets. The commercial telecommunications industry responded to the need with a set of standards called the Internet protocol (IP) Multimedia Subsystem (IMS). The subsystem is an architecture developed to deliver multimedia communications rapidly and efficiently. According to Adrian Hartman, senior manager and system architect at LGS Bell Labs Innovations and author of a white paper on IMS, the transition is a move to manage one network technology base over the long term.
The move to the new network will involve a migration period spanning several years when voice and data networks will work in parallel to each other. During that period, those technologies will migrate into a one-network environment. The convergence will bring together voice, data and video over IP. By using a standards-based architecture, services are open and standardized so multiple vendors can support the services and introduce them more quickly than in a closed environment. The open environment allows services to interwork and interoperate in a more sophisticated manner than they would in a standard framework. The convergence also results in a long-term cost reduction.
Hartman describes IMS as a technology direction for the telecommunications industry. The architecture was first developed in the mobile arena and is defined by the Industry Standards 3rd Generation Partnership Project (3GPP) and the 3GPP2. Hartman explains that those two bodies have standardized their architecture under IMS. While IMS started in the wireless field, it moved quickly to wireline and is being adopted by the cable industry as well. “There is an industrywide adoption,” Hartman states. IMS is IP-based and designed to be independent of any access network. This independence enables it to interoperate across access networks and devices.
Hartman depicts IMS as a standard for a portion of the core network architecture. If a network is broken into two parts, the core architecture affects the signaling and management of traffic in a core network. There is also an access network that affects the front end of any network. IMS deals with the core portion of the network.
IMS helps to solve the problem of stovepiped systems. Service providers in the commercial environment have been developing point solutions such as voice over Internet protocol (VoIP) and push-to-talk capabilities. The point solutions do not interoperate with each other, nor are they highly scalable. “You have many point solutions, and that’s an expensive proposition,” Hartman says.
IMS divides the core network into three layers, each of which has open, standard and defined interfaces. The lowest layer deals with access/transport; the middle layer, which Hartman calls the heart of the system, manages session control; and the highest level is the application layer.
The access/transport level includes media gateways and access devices such as telephones and workstations that operate in session initiation protocol (SIP). The protocol has been adopted industrywide for supporting multimedia communications and is an integral part of the IMS standard.
The session level manages the data, prioritizing data and voice and controlling quality of service to the end user. With IMS, users can share voice, data and video, including real-time video. These capabilities benefit the U.S. Defense Department by improving mission requirements. For example, troops could enhance situational awareness by passing video files. In addition, Defense Department personnel can connect to the network in a number of different ways.
Hartman explains that military members could connect at a desktop or through a mobile device. They could participate in a video session, engage in a conference with other participants, attend a training session and view a video. “What session control does is manage all these different ways that individuals can connect to the network,” Hartman states. It keeps track of how individuals connect to the network and what their preferences are.
Session control also performs policy management. It will indicate whether users prefer one service over another, manage network resources allocated to specific users and control policy about how many resources one user has relative to another user.
The IMS session control provides Defense Department personnel with a single sign-on, so common access card users would be able to access all the available multimedia facets in one session, whether from a mobile or fixed environment.
Also included in the session layer is a services broker function that supports interaction between SIP-based services and non-SIP-based services. For example, the network may include legacy or Web-based services that would be controlled in the session layer.
The highest level—the application level—interfaces down to the network. When an application is written, it can be written at a level above the detail of the network. “That detail is incorporated into these core network standards,” Hartman explains. Applications are services such as telephony, VoIP and conferencing. The applications work across various networks and vendors and interface to the level above called the enterprise services level. An application programming interface (API) is at the top of the application level. One of those APIs is SIP.
Hartman states that the advantage of having IMS technology is that it provides end-to-end policy-based bandwidth control so that the system is aware of the resources being used in the network and responds to issues. For example, the system could react to a point of congestion on the network. With an appropriate local area network at the transmitting and receiving ends, the quality of service can be managed completely. “This end-to-end quality of service management is very important,” Hartman says. It allows good-quality, high-rate data services and real-time video to flow over the same network, and it will prioritize the various services. Because voice services require close control of latency and jitter, IMS will give those features high priority so voice communications come through clearly. The network also will assign appropriate priority to information that must be delivered in real time.
The Defense Department is developing a standard that will provide real-time services over a converged IP network. The Defense Information Systems Agency (DISA),
“[IMS] provides an open-standards interface framework for supporting real-time multimedia services, and it creates an opportunity for the [Defense Department] to leverage the large base of commercial investment that will occur within that technology,” Hartman says. “It’s an opportunity to use commercial off-the-shelf technology in the [Defense Department] GIG.”
Hartman illustrates the importance of sharing various types of communications effectively by explaining the ways multimedia services can benefit a military community of interest. The community of interest would involve subject matter experts and analysts who are gathering data, accessing it on the network, turning that data into information and then sharing the information so it becomes real knowledge. Also in the community are commanders charged with making decisions. Tasks the community of interest may need to undertake to meet its objectives include supporting full multimedia communications, sharing information files and developing conferences in real time. IMS can help set up conferences more quickly because under the session-management function every person in a group is available. The network knows the preferences each individual has for being contacted. If people are mobile, the network can use location-based services to find them.
During a video- or teleconference, subject matter experts and analysts may make a recommendation for moving forward. If they need to share that information with the commander, they would send an indication of their intent. The commander would receive a real-time alert to the priority of the message. Commanders have the ability to click to respond and even to change from their current application to join the call.
Hartman explains that there are two ways that the Defense Department can use the advanced services. First, the wide-spread adoption of the IMS standard by the standards bodies and by some service providers already creates an opportunity for the Defense Department to interwork its services available to military personnel on base with those available in a wide area, either mobile or wireline. Additionally, wider adoption of IMS standards by service providers is expected. The additional interworking increases productivity because individuals can obtain similar services when away from their main locations, for example, a desk on base. It also increases availability of individuals. If people need to be contacted, they are reachable not only on base but also in the wide-area environment. Interworking services between the Defense Department enterprise and wide-area commercial services would be enhanced by sharing certain information when appropriate and by having similar technologies deployed. If the department has adopted parts of the IMS architecture, then that sharing across the department would be facilitated.
To keep the network up and running and to provide the necessary services to all parties, risk mitigations are built in. One risk area is redundancy. Redundancy requirements prevent a single point of failure. All assets are monitored, and the capability exists to support a failure in one portion of the system. Security is another area of risk. The IP and information technology worlds are subject to the risks inherent with the Internet, such as denial of services and hackers. The security architecture must take these threats into account, and security must be built into the products as well as provided in depth by the network itself.
Hartman shares that the objective of all the work of development, adoption and security is “to create an environment where we have blended services.” IMS can blend real-time services as well as support telecommunications, Web-based and multimedia services in the user environment. With IMS, the Defense Department has the ability to leverage commercial off-the-shelf technology in a multimedia system.