IP Multimedia Subsystem Network Research Articles

Inter-working between SIMPLE and IMPS

Instant Messaging is looked upon as one of the killer services for 3G (The Third Generation). This paper analyzes the differences between SIMPLE (Session Initiation Protocol for Instant Message and Presence Leveraging Extensions) and IMPS (Instant Messaging and Presence Services), which are two of the most popular standards for Presence and Instant Messaging in the world. IMPS is more mature and has been deployed in many communication systems, while SIMPLE is more suitable for an IMS (Internet Protocol Multimedia Subsystem) network, so inter-working between them is a hot topic in the value-added service field, but recently the research on the topic is just in the initial stage. Based on the analysis, a bi-directional protocol mapping is proposed to enable the exchange of Presence Information, instant messages and Group information between SIMPLE and IMPS systems. With the protocol mapping and OMA (Open Mobile Alliance) inter-working Architectural Model, an Enhanced Architectural Model is proposed to perform the inter-working functions which can not be completed by the current OMA Architectural Model. A method called IFT (Information Flow Trail) is adopted to describe the message streams and their exchanging between SIMPLE and IMPS. Based on the Enhanced Architectural Model, we implemented an IWF (Inter-working Function) system.

Improving performance and reliability of an IMS network by co-locating IMS servers

The IP Multimedia Subsystem (IMS) is an architecture for supporting multimedia services via a Session Initiation Protocol (SIP) infrastructure. IMS, specified by the 3rd Generation Partnership Project (3GPP), is increasingly adopted as the reference multimedia network architecture by providers of wireline and wireless infrastructure and associated multimedia application services. One of the characteristics of the IMS architecture is that many different and mandatory SIP proxies are used for each end-to-end SIP session. This may adversely impact the overall IMS call processing performance, which is already affected by the universal usage of SIP. This also makes each end-to-end SIP session dependent on the good functioning of many hosts, which decreases reliability while increasing significantly the end-to-end message latency. This paper analyzes the performance and quantifies the benefits of having the SIP servers running on the same host. It then explains which types of SIP calls in the IMS network can benefit from the co-location of IMS servers and shows how to design the IMS network to maximize IMS server co-location. Finally, it introduces Lucent Technologies' SIPia BUS software architecture, which implements the co-location capability by introducing a new SIP transport in a way that is both natural and non-disruptive for the SIP stack and the SIP user agent.

Service capability interaction management in IMS using the Lucent Service Broker™ product

The 3rd Generation Partnership Project/3rd Generation Partnership Project 2 (3GPP/3GPP2) designates the service capability interaction manager (SCIM) as a functional component in the IP Multimedia Subsystem (IMS). This paper focuses on how the Lucent Service Broker™ product has been designed and how it would be deployed to perform as a SCIM in an IMS network. We discuss the challenges in managing service capability interaction and providing blended services that are encountered in IMS and show how Lucent Service Broker flexibility is needed to accommodate the breadth of challenges. We describe how the internal structure of the Lucent Service Broker and its application programming interface (API) offer this flexibility while minimizing the effort involved in adding new SCIM logic. We also demonstrate how the Lucent Service Broker may be used to marshal IMS application resources on behalf of revenue-generating applications in various usage scenarios.

IP multimedia subsystem online session charging call control

An efficient IP Multimedia Subsystem (IMS) online charging system is important for operator revenue generation. However, 3rd Generation Partnership Project (3GPP) specifications do not adequately address how online session charging shall be accomplished for IMS networks, especially how IMS network elements such as the application server and the serving call session control function (S-CSCF) interact with the online charging server (OCS). To remedy the shortcoming of 3GPP online charging standards, this paper presents a policy-based IMS call control system that converges the multiple application servers and the IMS gateway functionality into one IMS node for online session charging. The IMS session charging call control system employs a session charging trigger mechanism that enables a real-time report of session information and provides budget control for online quota monitoring. It also enables service logic for multiple applications to be executed in a single node to greatly reduce traffic access between the IMS call session control function (CSCF) and the OCS.

Subscriber data management in IMS networks

Next-generation communication services will be driven by increasingly rich and distributed subscriber information. Current wireless networks have evolved such that subscriber information now resides in various elements e.g., home location register [HLR], prepay, voice mail, short message, and location determination systems). Convergence with the Internet promises significantly more personal information, such as presence, calendars, address books, buddy lists, pictures, and video. The home subscriber server (HSS) in the IP Multimedia Subsystem (IMS) architecture provides centralized storage for subscriber data. However, some application servers will also have their own subscriber data. As the quantity and variety of applications grow, it will become increasingly useful to provide unified views of subscriber data both within a network and across networks. The Lucent Datagrid™ software provides a telecom-targeted data integration capability, so that applications can use a logical “single-point-of-access” for user profile information inside a service provider's network.

Seamless mobility across IMS and legacy circuit networks

The growing desire of network providers to introduce support for voice over IP (VoIP) has created interesting challenges in the area of interoperability with existing wireless circuit networks. The 3rd Generation Partnership Project (3GPP) and the 3rd Generation Partnership Project 2 (3GPP2) standards have defined the IP Multimedia Subsystem (IMS) as the platform for convergence. By definition, IMS is access agnostic; it provides services and features through a common core network, regardless of the means of transport. However, the IMS standards are just beginning to address the challenges associated with interworking with existing cellular circuit networks. Achieving seamless mobility involves supporting both roaming and handoff between networks. This paper discusses the issues involved in providing seamless mobility for subscribers across the packet and circuit domains and proposes network-based solutions.

Domain management of IMS

The IP Multimedia Subsystem (IMS) enables converged networking through an application-agnostic architecture that is independent of the access network. The convergence aspects of IMS naturally require a convergent approach to managing the variety of possible applications of IMS. The Navis® element management framework (EMF) shares this application-agnostic architecture principle with IMS and is thus the natural enabler for the required convergent management approach. This paper will explore the development of the management solution for IMS by means of Navis EMF and high-productivity technologies such as Java 2 Enterprise Edition (J2EE <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> ) Enterprise JavaBeans <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> (EJB <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> ), Java <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> , Common Object Request Broker Architecture (CORBA <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> ), and Extensible Markup Language (XML) and will illustrate the application of the management solution in a variety of wireline and wireless solutions, including third-generation (3G) code division multiple access (CDMA) and Universal Mobile Telephone Service (UMTS <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> ) networks. The management solution for IMS is the operations maintenance center-core network (OMC-CN), which is a domain manager for network devices in the IMS network domain.

Multi-domain architecture for policy management inumts ip multimedia subsystem

The Universal Mobile Telecommunications System (UMTS) offers IP-based multimedia applications and services with end-to-end Quality of Service (QoS) guarantee. The key component providing these services is the IP Multimedia Subsystem (IMS) that uses Service-Based Local Policy (SBLP) management for QoS control. To support end-to-end QoS, the UMTS IMS network should be scalable, reliable and flexible in policy deployment and enforcement, characteristics that are not found in single-domain policy architecture. A hybrid policy architecture is proposed, in which a hierarchical architecture is applied to the multi-domain environment in a single operator UMTS IMS network, while a peering architecture is employed in a multi-operator UMTS IMS network. The proposed multi-domain policy architecture potentially minimizes the session setup delay and policy exchange traffic while maximizing network scalability.