Service Delivery Platform Options for Next Generation Networks, approved within the national German 3G Beyond Testbed

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1 Service Delivery Platform Options for Next Generation s, approved within the national German 3G Beyond Testbed Prof. Dr. Thomas Magedanz, Dorota Witaszek, Karsten Knüttel, Fraunhofer Institute FOKUS Berlin, Germany Abstract The notion of next generation networks (NGN) is based on the convergence of fixed and mobile telecommunication networks and the internet towards an all-ip environment. These NGNs support the provision of integrated information and communication services in face of increasingly becoming more complex value chains, enabled by so-called service delivery platforms (SDPs). Therefore an NGN is an environment of high complexity, in which different actors, such as fixed and mobile network operators, service providers, system integrators and an open set of application providers have to co-operate for the provision of advanced converged services. A converged service is the integration of voice, multimedia, web content and Web provided seamlessly over all kinds of access technology. This paper introduces the national German 3G Beyond FOKUS as an open technology integration playground for operators, vendors and most particularly application developers. An overview and comparison of the key service delivery platforms within the IP Multimedia Subsystem (IMS) is given. FOKUS established the Playground concept for all the stake holders. The Open IMS Playground consists of a variety of SIP application servers based on different programming paradigms, OSA/Parlay gateways and infrastructure components like Call Session Control Functions and Home Subscriber s. A guideline to the usage of these SDPs for the provision of innovative NGN services is illustrated. Index Terms All IP, IMS (IP Multimedia Subsystem), NGN (next generation networks), OSA/Parlay, SIP, SDP (service delivery platforms) I. INTRODUCTION In face of the variety of communications services, like the internet, voice calls, multimedia calls, , SMS, MMS confronted with different access technologies, network and end device capabilities, pre paid and post paid users there is the need of an abstraction layer with well defined interfaces to enable service integration and service accessibility. Future communication and information services should be provided seamlessly on top of different network technologies. This means that mobile services and applications could be accessed ideally from different end systems, different access networks in a customized way to the individual user demands. In this regard the notion of open service delivery platforms becomes of key importance. 3 rd Generation and beyond (3Gb) a buzzword which emerged in the beginning of the UMTS specifications - describes a complex communication environment which integrates existing and future wireless network technologies as well as open service delivery platforms based on state of the emerging information technologies, abstracting from the underlying network technologies. Due to the overall complexity of the converging network technologies and the increasing pace of introduction of new network technologies and service platforms, it is becoming increasingly difficult for the different players to maintain state of the art know-how and gain early access to all the upcoming infrastructures. Furthermore, in regard to integrated 3Gb network environments and 3Gb service platforms the maintenance of such an infrastructure is a costly task and requires a comprehensive know how and expertise. The open and independent provision of a 3Gb infrastructure testbed, preferably by independent, wellrecognised national organisations in order to assure maximum openness, is considered a key factor for the overall success of the national and international service development. Such an infrastructure is considered as the enabler for the rapid development of innovative market oriented applications and the corresponding building blocks, as it should act as a technology playground stimulating ideas and identifying research challenges by bringing together academia and industry, i.e. content providers, application developers, vendors and operators. Such a testbed environment has to provide testing and validation based on current state of the art technologies (GSM/GPRS/WLAN/Bluetooth networks, OSA/Parlay service platforms, hybrid services) as well as based on emerging technologies (UMTS, WiMAX, OFDM, IP Multimedia Subsystem (IMS/SIP/AAA), multimedia services). The Fraunhofer Institute FOKUS is providing such a 3Gb testbed in its role as national host testbed ( Figure 1 displays the reference architecture of the testbed indicating its general structure.

2 mhealth mgov mxxx. weitere weitere Other Apps Applications Web services 3Gb Roaming UMTS FDD/ TDD National 3Gb R&D Projects European 3Gb R&D Projects OSA Parlay GSM / GPRS IMS Service Platforms & Middleware WLAN a/b/x WiMax AAA DVB- S/T SIP Other weitere platforms 3Gb Technologies weitere Other Netws Engineering Tools,Conformance Testing, Measurments, and Management Fig. 1: The FOKUS Testbed Reference Architecture Developments of different layers e.g. network layer, service and middleware layer or the application layer take progress in parallel and join the OPEN IMS Playground for evaluation and for validation. II. SERVICE DELIVERY PLATFORMS A. Motivation for SDP and Open Technology Playgrounds The complexity of the next generation network and of the innovative NGN services demands the means to support the development and the deployment of services. Different wireless and wired access networks, such ISDN, GSM, GPRS, UMTS, wireless LAN, Internet etc., and corresponding terminals make the deployment of services difficult and time consuming. The services should be provided in an adapted way to the users, even if they change the terminal or access network. The provision of an appropriate platform with generic service components with well defined capabilities and interfaces and with environments for the service execution, service development allows a seamless integration of the different network technologies CORBA/Java 90 s 80 s Internet RPC IMS ISC Web SIP App. SIP Interface IP Nets Web/Application Parlay X Application OSA/Parlay Gateway GPRS/UMTS IN Plattform GSM Fig. 2: SDP Evolution based on IT evolution Multimedia 3rd Party OSA / Parlay Interface Intelligent Netw. INAP/CAP Interface Stored Program Control ISDN The service delivery platform supports e.g. the provision of location and/or presence information, advanced call and session control, multimedia messaging, streaming support, accounting or profiling. Research and development on this level is focusing mainly on the identification of useful generic functionalities as well as the way of providing these by means of different programming paradigms, such as Web, Corba/Java object interfaces, Intelligent s. Open Application Programming Interfaces (APIs) such as OSA, Parlay, or Parlay X abstract from the details of underlying network protocols. The service components could be particularly based on lower level network oriented application programming interfaces (e.g. Call Processing Language CPL) and protocols. Here the internet protocol (IP) and related protocols are considered as the key for future multi service networks. The trend towards all IP infrastructures, i.e. IP is considered as the harmonizing protocol level for voice and data integration, lead to the specification of IP Multimedia Subsystem, IMS. The development and deployment of new technologies, components and services can be speed up if the above stated building blocks and networks are in place in one single environment. These building blocks could be combined and integrated as needed by specific customers and projects. They form the so called open technology playground, an open environment where 3 rd parties can plug and play their own developments and solutions. This is in contrast to other vendor specific or operator specific technology testbeds. This means that content providers and application developers obtain an one stop shopping interface for gaining access to the state of the art in mobile telecommunications technologies to validate their ideas and developments. Furthermore, the test and development infrastructure provides the technology foundation for performing R&D work, e.g. by integrating available components, extending specific components, and/or developing add on components and APIs. B. 3GPP OSA / Parlay Based on the pioneering work of the TINA (Telecommunications Information ing Architecture) Consortium in the early nineties, the Parlay Group, a group of operators, vendors, and IT companies, has started in 1998 with definition of an open network Parlay API ([5]). This API is inherently based on object oriented technology and the idea to allow if desired by the business model third party application providers to make use of the network or better speaking the value added service interfaces. Originally designed for the use on top of IN systems, i.e. to open up IN systems for third party developers in fixed networks, the API evolved fast to a general API to be used on any underlying fixed, mobile, voice, or packet network. 3GPP has aligned in 2001 their work on an Open Service Access (OSA) API with Parlay.

3 Enterprise Domain Service Provider Domain Intranet Application OSA / Parlay API Router Elements Managed IP OSA/Parlay Applications Fire wall Parlay Gateway Elements PSTN Fig. 3: OSA/Parlay Architecture SCP Hosted Application Internet Hosted Appl Mobile Elements HLR Security Boundary Looking at this API in some more detail, it is important to recognise the open and extensible nature of the API architecture. The main idea is to provide in a dedicated network node known as OSA/Parlay Gateway operated by the network operator an open set of service interfaces, which exhibit specific value added service capabilities. This comprises call control, messaging, data session control, location, presence, charging, etc. Applications could access these capabilities thanks to object oriented technology (i.e. CORBA, C++, Java) easy to use interfaces to implement value added services. A dedicated interface known as the framework is in charge to register and discover new service interfaces, perform application and network authentication, service level agreements, etc. Important is the fact that the API is network independent, i.e. in principle each network (note that the type of the network doesn t matter) will provide its own OSA/Parlay gateway, and one application can make use of several gateways. This means that an application can run with the same logic simultaneously on top of a fixed telephone network and on a voice over IP network. One major target of OSA/Parlay is to make the networks programmable by means of the state of the art in middleware technologies. In order to make the network programmable by the application providers, the API has been enhanced by the use of the new Web paradigm, which combines the extensible Markup Language (XML), Web Service Description Language (WSDL), and Simple Object Access Protocol (SOAP). The idea of web services follows the idea, that in most cases the content providing starting point for information services is the interne. Furthermore, services could be constructed in packaging other remote services available in the web. In the telecommunications world, Parlay Web, and the more simplified version of it called Parlay X represent today the state of the art in Web. C. The FOKUS Open OSA/Parlay playground The OSA/Parlay playground ( brings together different OSA/Parlay gateways, gateway simulators, service creation toolkits, as well as demo applications in one single environment. The target is to establish an open and independent OSA/Parlay show and education centre to make this enabling technology available to all players of the future open telecommunications market. Thus the playground provides to both academia and industry early access to the most recent OSA/Parlay developments and serves as the foundation for technology coaching and hands on experience provision as well as own research and development in regard to functional and nonfunctional issues. At the time of writing the FOKUS OSA/Parlay playground features: different OSA/Parlay service creation tool kits (jnetx, Appium, Aepona, Lucent, etc.) different OSA/Parlay gateway simulators (JnetX, Lucent, Appium) different OSA/Parlay gateways on top of circuit switched and packet oriented networks including UMTS (FOKUS OCS, jnetx) as well as remote access to partner gateways (Lucent, Alcatel, Aepona) different local OSA/Parlay demo applications as well as remote access to partner applications (Lucent, Alcatel, Aepona) Figure 4 illustrates the OSA/Parlay playground blue print. We bring together the different players of the market in one central European location. Application developers can get early experience in the use of the API in order to prepare and investigate the benefits for their applications. Vendors can test their products against other vendor s products and in addition can obtain feedback from application developers. operators can see the technology at work and learn more about potential applications. Academic institutions can get in touch with this complex technology and get started. Parlay API Parlay GW Simulators Mobile Access Router UMTS Parlay SCEs GPRS SIP (SER) Intranet (IPv4/v6) WLAN b P- (JnetX) P-AS (Apps) P- (OCS / OCS-X) MGW GSM TAS (IBM, Appium) P-GTW (CTI) ISDN Internet backbone (IPv4/v6) Fig. 4: Open OSA/Parlay Playground Architecture Remote P-AS (Apps) Remote Gateways - Aepona - Alcatel - Lucent - Ericsson The heart of the OSA/Parlay playground forms the FOKUS Open Communication (OCS) for value added service provision on top of integrated circuit switched and packet oriented networks, which brings together classic Parlay APIs as well as Parlay X. The main target of this platform is to provide different levels of abstraction form underlying network capabilities and thus different levels of value added service programming within 3Gb environments.

4 Fig. 5: OCS within the OSA/Parlay Playground D. 3GPP IP Multimedia System The IP Multimedia Subsystem (IMS) defines as part of 3GPP Release 5 specifications an overlay architecture on top of the 3GPP Packet Switched (PS) Core for the provision of real time multimedia services. The IMS is based on the principles and protocols of the Internet defined by the IETF (Internet Engineering Task Force). Namely, the session initiation protocol (SIP) is used as the standard signalling protocol that creates, controls, modifies and terminates sessions between two or more participants. In addition, the Diameter protocol is used as the basis for AAA functionality provisioning within the IMS. Visited Netw. Dx Cx HSS (AAA) P-CSCF I-CSCF S-CSCF Sh ISC Application Media contact within IMS, S-CSCF handles the session state and is responsible for Service Switching, and I-CSCF is the contact point of an operators network. Media Gateway Control Function (MGCF) with Signalling Gateway, controls the Media Gateway, communicates with the CSCF depending on routing number for incoming calls from legacy networks and performs protocol conversion between ISUP and SIP. Media Gateway (IMS-MGW), interacts with MGCF for resource control and handles resources such echo cancellation. Multimedia Resource Function (MRF), which controls media stream resources: stream mixing, audio transcoding, speech recognition and others, interprets information from an AS and controls bearers Application (AS), acts as SIP Application, OSA/Parlay based Application, or CAMEL Support Environment. It has to be noted that today there does not exist any common programming paradigm for SIP value added services. Most often there is the notion of service scripts, namely, SIP servlets, call programming language (CPL) and Common Gateway Interface (CGI) scripts. An OSA/Parlay Gateway using SIP for call control also provides a platform to design valued added services in SIP environments. E. The FOKUS Open IMS Playground The IMS is deployed within the FOKUS 3Gb testbed environment as an open technology playground with the target of the validation of the 3GPP standards and to evaluate different products. ( Gm Home Netw. Mi Breakout Gateway Mj Media Gateway Fig.7: The FOKUS Open IMS key elements Fig 6: Simplified IMS Architecture The major components of the IMS include (see Fig. 6): Home Subscriber (HSS), masters data base for a user and contains subscription related data and user security information. It communicates via Diameter with the other IMS components. Call Session Control Function (CSCF), is split into Proxy CSCF (P-CSCF), Interrogating CSCF (I-CSCF), and Serving CSCF (S-CSCF), where P-CSCF is the first point of Different components, Application s, Application s simulators, service creation toolkits, and demo applications are integrated in the environment and can be used and extended by other R&D Institutes or from industrial partners. Users of the open IMS can test their components performing interoperability tests (The SIP Express Router, the one of the fastest existing SIP Proxies, can be used as a reference implementation and to proof interoperability with other SIP components) or in real environments as well as they can run and test their innovative services. E1. SIP CPL

5 The FOKUS SIP CPL implementation, figure 8, is done as a module of the SIP Express Router (watch to get more information about SER). It is fully compliant to the latest draft [12]. In addition there is an implementation of the draft Transporting User Control Information in SIP REGISTER Payloads that enables users to upload, download and remove their personal CPL scripts via the SIP REGISTER method. The differentiation on SER side if a user registers its self or a CPL script is done by a specific mime type. (application/cpl+xml for script registration). Application. Figure 9 Parlay X FOKUS E.4. OSA/Parlay Figure 8 SIP Express Router CPL Implementation Traditionally FOKUS has been very strong in OSA/Parlay implementations. A variety of Parlay modules is implemented and is mapped to the Session Initiation Protocol. To reduce the complexity of Parlay, a package was designed that handles all the CORBA middleware and automates as far as possible the parameter generation for the Parlay API. This package is called the Parlay Foundation Classes. It is meant to be a grant for application Designer and arose from the Parlay X to Parlay mapping. E.2. SIP Servlet Figure 9 shows the FOKUS SIP Servlet implementation. This converged (SIP / HTTP) Servlet container enables an integrated usage of SIP and HTTP by exchanging a Session ID. Possible scenarios are click to dial (HTTP->SIP) or the redirection to a personalized (SIP->HTTP) webpage. The user gets in his SIP replay the URL of the personalized site. The SIP stack is based on the JAIN-NIST (National Institute of Standards and Technology) reference implementation. The Diameter stack is based on open-source developments. The SIP Servlet Container is a 100% own implantation fully compliant to the SIP Servlet specification [14]. Figure 10 Open FOKUS E.5. Home Subscriber (HSS) The IMS FOKUS implements a HSS based on the specifications of 3GPP. FOKUS uses the Open Source "Diameter Client" (DISC) and extended the Open Source project Open Diameter ( to implement the complex functionalities of the Cx and the Sh reference points within a HSS. Both provide an implementation of the Diameter Base Protocol [8] plus several Diameter applications. DISC was developed by FOKUS and successfully applied in various national and international research projects. Figure 9 SIP Servlet FOKUS E.3. Parlay X On top of these Servlet Containers FOKUS offers a Web Service interface, namely the Parlay X API. This enables distributed Web Service Clients or other Web Service s to take advantage of this converged SIP Servlet E.6. Media Fraunhofer FOKUS has also implemented a Media. It is called SEMS. SEMS is a modular implementation that enables: Voic record messages and mail them.

6 ISDN Gateway: support calls from and to the PSTN. Conferencing: connect people within a conference room. Announcement: plays an announcement. Echo: test module echoing your voice. It includes a set of codec like G711./ G711.a / GSM III. EXAMPLE APPLICATIONS The IMS allows for coexistence of different server options. OSA/Parlay API can be seen as a part IMS application servers. It allows for provision of 3 rd party services and supports B2BUA services. On the other hand to implement services, where AS acts as a proxy, which manipulates ongoing call signaling, different solution is needed. Here the IMS defines an SIP application server, which can be implemented for example as a CPL script, or in Java in the form of SIP servlets. They are activated by incoming SIP messages (from a network side ) and perform some modification on the flow of signaling. They are not suited for example for Click2Dial applications. The IMS playground at FOKUS includes some of the possible services implemented for demonstration purposes, e.g.: SmartMessanger - an OSA/Parlay compliant service allowing to type in a text message once and send it to different recipients using different media formats which include: Voice (to be delivered via phone/voip), SMS, , Instant messaging. DocAvatar - an interactive health service for the mobile user. This service make use of Parlay X interfaces to accomplish the following tasks: -connects you with a real Doctor in a hospital or call center -localize you and sends an ambulance to your whereabouts - informs the ambulance about your location via SMS. Streaming Notification Service (SNS) uses IMS and allows a user to subscribe for an future event, which is real video transmission. Personal Call Manager implemented for IMS -a user can define its own preferences, how to proceed with incomings calls, accept, reject or redirect according to the time of a day and identity of the caller. The preferences are defined be the user with the use of a Web portal. In this usage scenario the application server acts as an B2BUA (back to back user agent). An incoming SIP call is directed to an application server which decide what to do with the call according to previously specified preferences and how to proceed in the case the call can not be completed as the destination is not available or the destination does not wish to be disturbed. IV. CONCLUSION The efficient research and development in the field of innovative multi media applications for 3G beyond environments requires the availability of adequate open wireless network and service infrastructures. In this regard, the Fraunhofer Institute FOKUS has established together with the project partner Verein zur Förderung eines Deutschen Forschungsnetzes e.v. (DFN-Verein), the German Research, and with funding from the Federal Ministry for Education and Research (BMBF) a national competence centre for the development of mobile services and applications for 3G beyond environments accompanied by the provision of a corresponding open 3Gb testbed. Unlike closed manufacturer- or operator-specific mobile wireless testbeds, the testbed is a fully open approach which includes the whole range of present and future use network technologies and service platforms for operational and application development. Users of the testbed include operators and manufacturers in the telecommunications sector and especially those providers of services, applications and content who are set to be the decisive actors in tomorrow s world of mobile communications. Canada USA Brazil 3Gb@FOKUS South Africa Fig.11: FOKUS Testbed connections to other Testbeds Finally, it is important to state, that in face of globalising markets, the FOKUS testbed is connected to other major 3Gb and NGN testbeds around the globe. REFERENCES [1] [2] dir/osa_parlay/content.html [3] [4] 3GPP: [5] Parlay Group web site: [6] IMS: 3GPP TS : IP Multimedia Subsystem (IMS) [7] SIP RFC 3261 [8] Diameter Base Protocol RFC 3588 [9] T. Magedanz: On the role of national 3Gb testbeds and their interconnection for setting up a European Open 3Gb R&D environment invited keynote speech at Interconnecting Heterogeneous Wireless s Workshop, European Commission, Brussels, Belgium, March 26, 2003, [10] Upcoming Int. Conference on Testbeds and Research Infrastructures for the DEvelopment of NeTworks and COMmunities, Trento, Italy, February 21-25, [11] Call Processing Language Framework and Requirements RFC 2824 [12] draft-ietf-iptel-cpl-09 [13] Common Gateway Interface for SIP RFC 3050, [14] JSR 116 SIP Servlet API Version 1.0, Israel China Indonesia Singapore Korea Japan