Dirk-Jaap Plas

Mobility management for sip sessions in a heterogeneous network environment

The next generation of communication networks is expected to create a heterogeneous network environment encompassing an ever-increasing number of different access networks and end-user terminals that will enable the introduction of and provide access to numerous feature-rich end-user services. It is essential that end users be able to roam from one access network to another if they are to enjoy a seamless roaming experience, which is especially important for multimedia applications such as voice, audio, and video. This paper describes how to make such a roaming experience possible in multimedia applications based on Session Initiation Protocol (SIP). It also describes several mobility management solutions and compares the suitability of SIP sessions for roaming across General Packet Radio Service (GPRS), Universal Mobile Telecommunications System (UMTS), and wireless local area network (WLAN) networks. The comparison is based on the implementation of a prototype. The advantages and disadvantages of each mobility management solution are discussed, as are the issues encountered during the implementation of the prototype.

Web services in third-generation service platforms

In third-generation (3G) networks, third-party service developers will have access to the mobile network resources using open network interfaces, such as the 3rd Generation Partnership Projects (3GPPs) Open Service Access (OSA). The service platforms that offer these interfaces provide interoperability, third-party access, and ease of use, which goes beyond the capabilities of existing intelligent network technologies. OSA is usually implemented using CORBA∗ object middleware. To accommodate a broad community of developers and scenarios of deployment, middleware technologies other than CORBA should be supported as well. In this paper we discuss Web services, an emerging Extensible Markup Language (XML)-based middleware technology that is especially targeted at the Internet community. We describe the technical benefits of both Web services and CORBA in an OSA context and look at the main issues and possible solutions with respect to offering Web services-based access to the OSA interfaces. We also describe a prototype to validate our conclusions.

Using Message Reflection in a Management Architecture for CORBA

The availability of object middleware, such as CORBA, is rapidly being accepted as a means for cost effective and fast development for a wide range of distributed applications. Distributed applications that are built using these technologies often comprise many objects and become more and more complex. The deployment of such large distributed applications requires a significant improvement of management methods and tools. In this paper, we present a management architecture for object middleware based systems. We use message reflection to extend the middleware layer with management capabilities, i.e. we monitor the application by observing the messages exchanged between the objects of the distributed application. We argue why management should be transparent to the application developer and show that message reflection supports this management transparency. We have compared different mechanisms to implement message reflection in CORBA, and argue why portable interceptors are the most suitable. Finally, we describe our prototype and the lessons we learned.

A structured framework for federation between 4G-service platforms

Service platforms are gradually becoming common functional entities in the next generation networks, i.e., in 4G-environments. By providing value-added capabilities to networks and end-users, and facilitating service provisioning for 3/sup rd/ party service providers, the service platforms will prove indispensable in the near future. However, with this increased importance, the need for cooperation between service platforms also increases. The use of the well-known concept of federation results in a structured framework to this cooperation. The proposed framework carefully defines the notion of service platform domain, applies the concepts of domain federation and service federation to these service platform domains, and prescribes the construction of federations between these domains. The benefits of the resulting service platform federation for all involved parties (end-user, network operator and service provider) are explained by the example of the home environment capability.

The 4GPLUS Project, Overview and Main Results

A 4G-environment is based on the integration of 3G mobile and other wired and wireless technologies into an all-IP network environment. Central to such an environment is a 4G-service platform, which offers services such as AAA, mobility management and session control, and also mediates between the users and providers of these services. Each service platform and its associated users, service providers and access networks constitute a service platform domain. Extension of offered functionality and expansion of coverage is obtained by federation between multiple service platform domains. In the 4GPLUS project a conceptual framework is developed for 4G-environments, which specifies the functionality and structure of the 4G-service platform and the concept of federation. Several key aspects of this framework have been refined, implemented and prototyped within this project. This paper provides an overview of the 4G-concepts developed within the project and the main results achieved.

Validation of the Open Service Access API for UMTS Application Provisioning

UMTS networks will allow the deployment of new types of applications, that are rich, interactive and multimedia capable, because of increased bandwidth, richer devices and location awareness. These applications are not necessarily provided by the network operator, but can be created and deployed by any third party. However, these third parties will need access to the UMTS core network capabilities, especially when it comes to call related services, location based services and services that charge for certain content. Intelligent Network (IN) based service creation and delivery platforms deployed in current 2G and 2.5G networks do not offer suitable interfaces for this, since third parties need to have detailed knowledge and expertise of low level, telecommunication specific protocols and can jeopardize the integrity of the network. The recent activities within the standardization bodies 3GPP and ETSI SPAN, and the industry forums Parlay and JAIN show an increased interest in the area of open network Application Programming Interfaces (APIs). The Open Service Access (OSA) specification is a collection of open network APIs for UMTS application provisioning defined by 3GPP. OSA is meant to allow third party application development and deployment by means of open, secure, and standardized access to core network capabilities, while preserving the integrity of the underlying network. We describe a prototype implementation, and list the possibilities and limitations of the OSA specification.