Richard Good

The UCT IMS client

The UCT IMS Client is a free open source implementation of a 3GPP IMS Client. The project was started with the goal of creating a flexible and extensible code base for researchers and industry specialists to use the many communication services offered by the IMS. Since its inception in 2006 the client has grown, both in terms of its stability and its feature set, and is used worldwide by IMS enthusiasts as a means to experiment with IMS without any associated risks or costs. This paper describes the history of the project, the software architecture, the supported services and provides results of the various interoperability tests that have been performed between the UCT IMS Client and other freely available IMS Clients.

A multilayered hybrid architecture to support vertical handover between IEEE802.11 and UMTS

Telecommunications advances have created the need for a high speed, ubiquitous network capable of catering for diverse application domains. This Next Generation or 4G network can be achieved through the interworking of several existing architectures to form a seamless global network. An important issue involved in interworking is vertical handover.This paper reviews mobility protocols, Mobile IP and the Session Initiation Protocol (SIP), and compares their ability to implement vertical handovers. A multilayere, hybrid architecture is proposed and described, which incorporates both SIP and Mobile IP. A Mobile IP framework is introduced and evaluated, based on its ability to implement vertical handover.

The UCT IMS IPTV Initiative

As revenues from voice services continue to fall, telecommunication operators have begun to develop and acquire new services in an attempt to generate new revenue streams and to avoid losing customers to third party service providers. One such service that many, if not all, operators are investigating is Internet Protocol Television (IPTV). IPTV provides broadcast television channels as well as Video on Demand (VoD) content to subscribers, delivering the video content using the Internet Protocol (IP). The UCT Advanced IPTV v2.0 system is an open source implementation of an IPTV system based on ETSI TISPAN standards. The proposed system also incorporates multimedia content adaptation methods in order to adapt video to meet varying client terminal devices and access network characteristics. This paper describes the history of the project followed by the relevant ETSI TISPAN standards. It then goes on to discuss the software architecture of the developed system and provides results of several transcoding tests.

XML-Driven Framework for Policy-Based QoS Management of IMS Networks

Policy Based Network Management (PBNM) simplifies the administration and management of communication networks. However due to the wide variety of policy representation forms, interoperability between different entities of PBNM systems becomes a concern. The Common Open Policy Service (COPS), which was standardized for policy control between a Policy Decision Function (PDF) and Policy Enforcement Point (PEP) had considerable shortfalls in efficiency and flexibility - its successor the Diameter protocol exhibits interoperability shortfalls. An XML-based policy provisioning solution presents great modeling capabilities that may overcome these shortfalls. The IP multimedia subsystem has adopted PBMN as the mechanism for resource and admission control. This paper reviews an XML- driven architecture for policy control of DiffServ networks, and explores the incorporation of the proposed architecture into the IMS framework to perform policy control and enforcement. Proof of concept results of the XML-based policy control architecture are presented alongside design requirements for using it as an alternative to diameter for IMS policy control.

End to end session based bearer control for IP multimedia subsystems

The IP Multimedia Subsystem (IMS) is a converged service enabler that facilitates the rapid deployment of multimedia services in IP networks. The IMS defines a Policy Based Management model to ensure QoS-enabled connectivity by providing mediation and interaction between applications and transport layer resources.

Critical Issues for QoS Management and Provisioning in the IP Multimedia Subsystem

This paper presents state-of-the-art research efforts in implementing a Policy Based architecture for Quality of Service management and provisioning of network services in the IP Multimedia Subsystem (IMS). While Policy Based Network Management has been adopted by the Third Generation Partnership Project and the Telecoms & Internet converged Services & Protocols for Advanced Networks as the solution for managing QoS in the IMS, the proposed mechanisms are sorely lacking in many aspects. First, the policy logic and decision mechanism are not specified, nor is the actual resource allocation procedure. Second, while the IMS is being tailored as the Service Delivery Platform for Next Generation Networks many of the QoS provisioning solutions are designed specifically for UMTS as an access network and need to be enhanced to support other technologies. In the current specifications, 3GPP is already evolving to support Packet Cable, WLAN and WiMAX accesses, but their respective policy-related sections are still void. Furthermore the proposed solutions do not specify how the network processes user requests for services in the IMS infrastructure. This article analyses critical QoS management issues within the IMS, and proposes solutions by designing a Policy Decision Function, which is the central element in the policy architecture. These solutions are presented in a proof of concept implementation running in a real IMS testbed making use of the Open Source IMS Core and considering the management of QoS in different scenarios.

An evaluation of transport layer Policy Control in the IP multimedia subsystem

The 3GPP IMS is a ubiqituous communications architecture that makes Internet technologies available to any user, anywhere and at any time. The success of IMS technology will depend heavily on customer uptake of services. Network operators need to justify charging for services that are typically freely available on the Internet - one way to do this is by introducing reliability through QoS provisioning. The IMS and service delivery platforms in general are topics of huge complexity, consequently testbeds will be necessary to expose these architectures to an open set of developers. This paper presents the UCT policy control framework a 3GPP compliant, open source and freely distributed architecture designed for QoS provisioning in the IMS. Important test scenarios and results are presented that investigate the network overhead and session setup delay introduced by such a policy control architecture.

Application driven Policy Based Resource Management for IP multimedia subsystems

Policy Based Resource Management will form the cornerstone of service differentiation that will drive IMS service deployment. While the IMS specifications are largely finalized, the policy based QoS provisioning architecture still faces many deployment challenges including flexible, application driven policy control, end to end policy provisioning and policy refinement. To accelerate the maturity of this technology open test-beds are necessary to expose the complex systems to an open set of developers. This paper proposes a Multilayered Policy Control architecture that extends the general resource management function being standardized; this extended architecture gives application developers greater control over the way their services are treated in the transport layer. Furthermore the architecture is implemented in the form of a 3GPP compliant, open source and freely distributed test-bed architecture - the open areas of policy representation, application-policy interaction, policy profiling and policy refinement are addressed. This open test-bed will serve to foster innovation in the field, increase collaborative co-operation and accelerate the maturity of these technologies. The framework is subjected to vigorous validation and evaluation tests - while the effects the architecture has on session setup delay and signaling overhead are not insignificant they are found to be acceptable.

Centralized policy provisioning for inter-domain IMS QOS

The IP Multimedia Subsystem (IMS) has been standardized to offer multimedia services over an Internet Protocol (IP) based infrastructure. These services require different Quality-of-Service (QoS) classes, hence the importance of providing QoS services through seamless interconnection networks is fueling an increasing interest in the Next Generation Network (NGN). A critical issue regarding deployment of a QoS service is the ability to provide the network and also the service across administrative domains. Flexible Inter-Domain QoS provisioning requires tight coordination between the session and transport levels and can not be considered as a transport level task only. Even if operators in different domains utilize IP QoS agreements, they may be incompatibly configured. In this paper we identify the limitations in the current IMS policy control architecture, and propose a centralized policy framework for Inter-Domain QoS based on the IMS architecture.

Optimized IP-CANs to support best charged IMS scenarios

The pricing and charging mechanisms used in Next Generation Network (NGN) deployments will influence the profitability of network operators. NGNs present an opportunity for the success of service delivery platforms designed for IP multimedia communications, like the IP Multimedia Subsystem (IMS). Moreover, they present a platform for the delivery of a multitude of applications and services to users with different expectations and budgets. Although usage-based charging schemes are more meaningful, some recent successful Internet-based applications and services have attracted widespread usage due to enforcement of flat-rate pricing. The choice of a pricing scheme often has a one-to-one relation to the access network technology and the quality of service guarantee. Flat-rate pricing may easily be associated with best effort transport. This implies that some users opt for services without QoS guarantee when favoured by the pricing methodology. This paper explores scenarios where services with different QoS requirements available to users with varying pricing preferences can be provided over a set of IP connection access networks (IP-CANs) of the IMS. We explore the use of different pricing schemes for different IP-CANs of the IMS. We perform testbed evaluations and present results depicting the income patterns of networks enforcing different pricing and charging schemes for VoIP and IPTV services. Moreover, we emphasize the use of simplified pricing schemes on communication networks.