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IMS Feature Article

TISPAN — Delivering a Quality-Assured Application Experience

By Richard Cardone

IMS Magazine

Next-generation network architectures promise a service-rich world that delivers quality assured IP services across a converged IP network to an increasingly mobile subscriber base. The new architecture promises to allow subscribers to define their own service catalog via self-service portals and enables them to personalize delivery parameters for offerings such as VoIP, VoD, and IPTV. The new services represent a significant growth opportunity for service providers. However, the current network architecture is not designed to support the array of rich media services, or the per session quality demands associated with these next-generation IP services.With the transition of rich media services onto a converged IP network, the dynamics of bandwidth consumption and session duration are undergoing significant changes. The subscriber session is evolving from a simple data request/response — such as a Web page request, an instant message chat session, or a file transfer that consumes bandwidth in kilobytes per second and lasts under a minute — to a collaborative, rich-media session that consumes bandwidth in megabytes per second and can last for hours.

Moreover, subscriber expectations around voice and video services are extremely high. Traditional voice services provide a consistent level of quality, unlike today’s VoIP (define - news - alert) services that have highly unpredictable quality from one call to another. The same can be said for video services. Today’s television experience provides consistent quality and, with the introduction of high-definition TV, the viewer’s expectation levels continue to rise.

As these traditional applications transition to the IP network, the impact will be tremendous. However, the full impact of these changes will not be realized until the trend toward blended services — voice, video, and data in a unified application — and mobility are factored into the service delivery equation. These two factors are going to force the network to be able to accommodate the transition of real-time transition of session characteristics to accommodate the addition of voice or video to a data session, or from a wireline to a wireless for example.

When you combine the changing subscriber session dynamics with the transition of quality sensitive services and the impending impact of blended services, mobility, and presence, the full scope of the challenge facing service providers becomes clear. To successfully manage rich media subscriber sessions the next-generation network must have inherent subscriber- and application-awareness. This means it must be able to identify the subscriber, his access method, and the device type he uses to access the network, as well as monitor and adjust for transitions
in real-time.

The final element propelling the movement from legacy to next-generation is competition. Historically, service providers worried only about other service providers within their own market — wireline, wireless, or cable. Now, not only are providers looking at each others’ territories for new service opportunities (e.g., cable providers in the VoIP market), but new disruptive entrants are coming into the market are delivering applications that leverage the service providers network to reach the same subscribers, without the encumbrance of network ownership. The new application providers are the true catalyst in accelerating the timelines for service providers, who must create a next-generation network architecture that provides a sustainable advantage in the battle for the next-generation subscriber.

As a result, service providers look to next-generation network standards to provide a roadmap to accelerate the evolution of their networks from today’s silos (per service overlay network) to a converged architecture that provides an
open framework for the rapid introduction of new services across both wireline and wireless networks. To date, the focus has been on IMS as the primary driver for this next-generation network services environment. However, to successfully deliver the full range of applications, IMS alone is not sufficient.

Since IMS has predominately focused on the delivery of SIP conversational services in a wireless environment, much work needs to be done to create an environment that can deliver SIP (IMS - voice), non-SIP (VoD, IPTV, etc.), and “over-the-top applications” (those created and delivered by third-party application providers) with assured levels of quality, on a per-session basis, across both wireline and wireless networks. The final element propelling the movement from legacy to next-generation is competition.

A key standard assisting in the acceleration of the fixed/mobile convergence market is ETSI TISPAN. The TISPAN wireline standard leverages the IMS application framework and adds multiple subsystems. The subsystems facilitate the wireline subscriber’s network attachment, empower applications to dynamically request network resources with well-defined session characteristics, and enable the network to confirm resource availability. Then the subsystems either admit or deny the session based on the subscribers entitlements, the session requirements, and the available network resources.

Two critical subsystems facilitating these capabilities on the wireline network are the Network Attachment Subsystem (NASS) and the Resource and Admission Control Subsystem (RACS). NASS enables subscriber context (presence — access type, device, status) to be integrated into the session setup process. RACS enables applications to request resource availability and specific levels of quality at the time of session invocation. A crucial element of TISPAN is the ability to apply these capabilities to SIP, non-SIP, and third-party applications.

Within TISPAN, IMS is located in the Services Subsystem, and receives subscriber information from the NASS. It then requests application sessions on behalf of the subscriber via the RACS. This enables the successful delivery of any application created within the IMS application framework across a wireline network without the re-creation of the application.

A major focal point for TISPAN is the ability to guarantee resource availability and assure quality on a per session basis. Wireline networks have focused on these aspects of session setup due to an increased focus on video services, since these services consume large amounts of bandwidth per session and their success is greatly impacted by the subscriber’s perception of the quality of the experience. These factors led TISPAN to create a robust, policy-driven control layer that mediates between application requirements and network resource availability.

This real-time resource and bandwidth control capability has led service providers to leverage the TISPAN architecture to create an open, standards-based service delivery environment that embraces IMS, as well as other services subsystems. TISPAN enables service providers to realize their vision of a service-rich world that accelerates the delivery of quality-enabled SIP, non-SIP, and over-the-top applications across a converged IP network. By uniting the IMS and TISPAN architectures, service providers are accelerating their ability to fulfill their subscriber’s demands for rich application experience that enables mobility — fixed mobile
convergence — and is delivered across a unified IP service delivery platform.

Richard Cardone is director of marketing at TAZZ (news - alert). For more information, please visit

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