An IMS Architecture and Algorithm Proposal with QoS Parameters for Flexible Convergent Services with Dynamic Requirements

This chapter describes the support for IP based multimedia services on Third Generation (3G) wireless cellular networks. While earlier cellular networks offered only basic IP connectivity on a best-effort basis, 3G networks provide explicit support for real time multimedia services with guaranteed Quality of Service (QoS). As a result, they can offer traditional voice telephony, rich telephony services and multimedia streaming over IP, both inside a 3G network and in conjunction with external networks such as the Internet, the Public Switched Telephone Network (PSTN) and the Integrated Services Digital Network (ISDN). In fact, 3G networks will deploy for the first time in a large scale technologies such as IP version 6 (IPv6) and policy based IP QoS, spearheading the introduction of such technologies into the Internet. The two most important aspects of 3G networks with respect to IP based multimedia services are the IP Multimedia Subsystem (IMS) and the Multimedia Broadcast / Multicast Service (MBMS). The IMS enables complex IP based multimedia sessions to be created with guaranteed QoS for each media component. Example applications include voice telephony and video conferencing. The IMS interoperates with both traditional telephony services and external IP based multimedia services. The MBMS provides native IP broadcast and multicast support in 3G networks, allowing high bandwidth services to be economically offered to multiple users. Example applications include video streaming via multicast and location based services via broadcast. The MBMS interoperates directly with IP multicasting. While both the IMS and the MBMS are IP based, their standardization is proceeding independently. It is however clear that their combination would allow numerous new services to be provided. The outline of this chapter is as follows. In Section II we give an overview of cellular networks and their evolution, while in Section III we describe in detail a specific 3G network, the Universal Mobile Telecommunications System (UMTS). Section IV presents an introductory description of the features and services provided by the IMS and the MBMS. In Section V we provide the details of the IMS, including service architecture, session setup and control and interworking issues. Section VI describes the MBMS in the same manner as for the IMS. Finally, Section VII discusses the QoS issues for IP based multimedia services, describing the overall QoS concept, the policy based QoS control scheme and its application to IMS sessions. At the end of the chapter, Tables II and III list the acronyms used. An extensive UMTS vocabulary is provided in [1].

IMS (IP multimedia subsystem) is a main trend of development NGN. The base of IMS is an Internet Protocol which initially did not provide support for quality of service. However, for the transmission of multimedia streams is necessary to ensure a given level of quality of service (QoS). Therefore, IMS QoS estimation is a necessary task but a high complexity of network topologies and a large number of information flows makes it difficult to solve this problem. In IMS network, QoS support is provided by the interaction of systems of IMS on control and application planes. This interaction based on the signalling message exchange that also has delay. This paper presents the results to create a nodal tensor model of IMS network for delay analysis. In this model, the main systems of the IMS network such as CSCF (Call Session Control Function), HSS (Home Subscriber Server) etc. are represented as a single-server queuing systems. Model is formed in accordance to the postulates of the tensor analysis of networks. Moreover, proposed model allow estimating the delay time as for the individual routes, and for the whole network. Research of the model allowed determining such distribution of traffic that resulted to the minimum value of the delay that in turn leads to increased QoS of information flows in an IMS network.

The main stages of the historical development of telecommunication networks are shown. It is noted that today the most common concepts are NGN (Next Generation Network), supporting the functionality of Triple-Play Services (triple services – voice, video and data transmission), as well as IMS (IP Multimedia Subsystem), which combines cellular technology and landline communications. They are able to provide a wide range of services: basic, additional, intelligent. In addition, IMS is able to provide mobile services. The IMS architecture layers are presented – transport layer, control layer; layer of service and application servers. Particular attention is paid to the layer of service and application servers. Based on the analysis of ITU recommendations, the main telecommunication services quality indexes are determined, namely, the time of service provision, the length of the queue that the service request falls into to wait for service on the server, and the probability of refusing to provide services. Based on the proposed mathematical models of the NGN intelligent superstructure, analytical expressions are presented for calculating the quality indexes of intelligent services in NGN for one type of service and for K types of services, taking into account the self-similarity of traffic, and without taking into account. To evaluate the quality of services in IMS, it is proposed to use the approaches of queuing theory and tensor analysis. Tensor analysis offers a mathematical apparatus for transforming coordinate systems, considering IMS as a set of geometric objects whose projections are different in different coordinate systems, but the physical properties of the objects themselves do not change. Expressions are proposed that make it possible to calculate the following QoS indexes in IMS: average queue length, average residence time of an application in the system for all types of services in IMS. It is considered that the incoming traffic is the simplest. Further development of the work is to take into account the self-similar nature of traffic, which is created by the flow of requests for services that come to IMS, as well as the limitations of the server buffer, which will allow a more accurate assessment of the quality of services in IMS.

BT has commenced the switch-over to its 21st Century Network — an all-IP based network which will reduce costs and provide a more ‘innovation-friendly’ platform where exciting new services can be rolled out much more quickly and cost effectively. Increasing computing power and openness on the client device coupled with the move to an IP environment fundamentally alters the competitive landscape for service provision, making it much harder to control the customer’s service experience. Further complexity is introduced by convergence — the requirement for services to run across a multitude of networks and devices. The challenge is to create an infrastructure capable of delivering the exciting new own-build and third-party converged services users want while preserving ease of use and security. The IP multimedia subsystem (IMS) element of the 21CN architecture is a key enabler in reaching these goals. Alcatel-Lucent is a vendor with a strong track-record both in supplying IMS products and in ongoing research activities, considering improvements and extensions to the current IMS standards. This paper summarises activities to date in a research collaboration between BT and Alcatel-Lucent which is looking at the area of improved intelligence in the provision of converged services over an IMS architecture. The collaboration utilises capabilities produced by Alcatel-Lucent’s research department called the Reachability Server to implement a number of novel converged service scenarios. The paper introduces the Reachability Server, describes the collaboration, summarises the scenario implementation work completed to date and presents a number of conclusions and observations.

As the next generation network NGN core network solution, IMS (IP multimedia subsystem) can support a variety of terminal access method and provide a foundation for the fixed network and mobile network integration. IMS is using the session initiation protocol (SIP) as its core control protocol to establish, manage and terminate multimedia services. IMS provides multimedia communication services based on data, voice and video, it gives users an unprecedented experience. Satellite mobile communication system has become an integral part of the global communication network. It can be seamlessly connected to the global communication network, which provides a strong complement to the ground network coverage. In recent years, the research and implementation of multimedia services through satellite access to the IMS core network has also been concerned. However, the problem of propagation delay of satellite channel has a great influence on the QoS (quality of service) of IMS access. Therefore, the application of IMS streaming media transmission and SIP signaling interaction must also consider the propagation delay of the satellite channel. In this paper, the process of satellite access to IMS and the transmission delay of satellite communication was simulated; the complete IMS voice and video service access and communication process was designed and implemented. In order to solve the problem of the propagation delay of the satellite in the communication process, the session signaling process was optimized.

IP Multimedia Subsystem (IMS) is a novel architecture, which is the basis for the new network architecture for future mobile applications incorporating voice, video and many other multimedia services. It is also the ultimate goal for the development of ALL-IP network, which is supported and developed by China Mobile many other famous operators all over the world. IMS is an overlay network on top of IP that utilizes SIP (Session Initiation Protocol) as the primary signaling mechanism. Because of its IP based architecture, IMS faces many new security challenges both in core network layer and application layer. Therefore, this paper provides an overview of the IMS architecture and presents some researches and discussions on the relevant security challenges.

IP Multimedia Subsystem (IMS) is the main solution for new generation networks providing multiple services proposed by third generation partnership project (3GPP). IMS architecture is based on several protocols guaranteeing connection and data transmission. Among these protocols, Session Initiation protocol (SIP), which is regarded as the main IMS signalisation protocol, hence considered a target for several attacks. To secure this protocol, 3GPP proposed an authentication and key agreement protocol called IMS-AKA. However, this protocol suffers from weaknesses in terms of complexity and user identity protection. In this work, we are particularly interested in IMS- AKA+ protocol, an improved version of IMS-AKA. This work aims to analyse performances of IMS-AKA+ against IMS-AKA using simulation and AVISPA specification. Results showed that IMS-AKA+ outperforms IMS-AKA resisting to many security attacks such as Spoofing attacks, SPIT and Dos-Synchronization. In addition to this, we propose an initial approach toward securing media plane by introducing a shared key at the end of IMS-AKA+ process using Secure Real Time protocol (SRTP).

Todaypsilas user wants exciting new services at reduced costs. Legacy ldquovoicerdquo services are considered to be bare minimum. To satisfy their customers and be competitive, Telecom service providers are pressured to provide converged and differentiated services at reduced cost. IP multimedia subsystem (IMS) is touted to be next generation telecom architecture that enables service providers to achieve this requirement. IMS architecture allows service providers to offer a variety of multimedia services in the service layer. Service providers today are building an eco-system with partner vendors to offer new services in this layer. With the success of person-to-person and person-to-content services in the Internet world, it becomes more compelling for mobile device manufactures and service providers to reach out to developer community to create more innovative applications with IMS infrastructure. This paper describes how ldquoservice creationrdquo focus is being shifted from operators and mobile device vendors to third party developers. It explores the benefits of having a service creation platform to aid in developing such services. It outlines the elements of software development kit (SDK) which will help in maximizing productivity and enables developers to focus on creativity. This paper analyzes the need for a complete simulated setup for developers to create and test their services before deploying into real network. There are different service creation environments that are available like service delivery platforms (SDP), JAIN SLEE, and OSA/Parlay etc. In this paper the primary discussion is on the usage of standards based API in IMS/SIP SDK. It dwells more into JSR API for client development and application server development. It also touches upon how SIP SDK can be interfaced with Web 2.0 components.

4G wireless communication expects to integrate different radio access technologies together to meet wide expectation from users and to support mobility. Call Admission Control (CAC) plays important role in such heterogeneous environment to effectively utilize network resources and to meet user QoS. This paper proposes IP Multimedia Subsystem (IMS) based integrated architecture for UMTS-WiMAX-WLAN overlay networks and Traffic Aware Dynamic Speed Sensitive CAC (TADSS-CAC) for these integrated heterogeneous networks. IMS architecture was designed by 3rd Generation partnership project (3GPP) and its main goal is to provide seamless multimedia connectivity between 3GPP standard and non 3GPP standard networks. In this paper IMS entity is used for interworking 3GPP based UMTS and non 3GPP based WiMAX and WLAN. Existing Speed Sensitive CAC (SS-CAC) preferably admits high velocity users to high coverage area network and low velocity users to low coverage area network that avoids unnecessary handoff and signaling overhead caused by high velocity user admitted to low coverage network. SS-CAC not considers specific network feature and traffic type for admitting calls. The Proposed TADSS-CAC preferably admits high velocity users either to WiMAX or UMTS (high Coverage networks) based on service type and low velocity or static users to WLAN except voice service. TADSS-CAC preferably admits low bandwidth loss tolerant delay sensitive services (eg., voice) to UMTS and huge bandwidth QoS restricted services (eg., video streaming, video conferencing) to WiMAX. TADSS-CAC also provides dynamic bandwidth reservation for handoff calls based on traffic condition that decreases packet loss, delay and increases network throughput. The proposed TADSS-CAC is applied for loose, tight, hybrid coupled UMTS-WiMAX-WLAN networks and performances are compared with existing SS-CAC.

The Third Generation Partnership Project (3GPP) has specified the IP Multimedia subsystem (IMS) as a service control platform that allows creation of new multimedia and multi-session applications utilizing wireless and wireline transport capabilities. Supporting many types of communications such as instant messaging (IM), push-to-talk cellular walkie-talkie service, and multimedia telephony; the IMS should provide mechanisms to negotiate various levels of Quality of Service (QoS) that should be established at session set-up and maintained throughout the life of the session. In this paper we will cover the accessing of IMS service using Wireless LAN (WLAN) in the transport plane. We will investigate the interworking architecture specified by 3GPP, and propose a framework of the QoS provisioning required in establishing IMS sessions from/to WLAN terminals

Users and enterprise needs will drive multimedia service evolution for both mobile and fixed operators. IMS (IP Multimedia Subsystem) is a recognized standard of 3GPP group. IMS is well integrated with existing voice and data networks, while adopting many of their key characteristics. The SIP servers are the key part of the IMS structure. They are the main components responsible for processing and routing messages. With communication networks getting more and more present in our daily activities, network outages or significant degradations of the quality of service (QoS) become less and less tolerable. Our research works on improvement of the QoS in IMS networks. It is base in the one hand modeling traffic and on the other hand dimensioning traffic. These performance optimizations are essentially dedicated to the traffic of input and output flows at SIP servers. We build OpenSource IMS platform under UBUNTU Linux distribution.

The IP Multimedia Subsystem (IMS) is a converged framework for delivering voice, video and data communication services to mobile and fixed users. The present operator-centric IMS model, which assume a single operator for the access network, IMS core and application servers, restricts if and how users can access services beyond the IMS core network. The present IMS model, by limiting the subscribers' choice might be rejected by many end users. User-centric service provisioning should establish the users' control and thus commence the customer interest for IMS. In this paper, we study the problems that a user-centric IMS architecture should address, and broaden the scope of our previously designed, third-party service enabled IMS model [21] by showing its use in user-centric service provisioning. Third-party offered service subscription and session setup procedures are explained with two use cases. The Users' profile management and privacy endurance, possible terminal implications are also discussed in the context of a user-centric IMS model.

To support user mobility across different devices, communication session continuity should be enabled at session initiation and during a session. The session continuity can be managed by either a user or dedicated network nodes such as back-to-back user agent (B2BUA) in IP Multimedia Subsystem (IMS) architecture. When network manages the session continuity, user experience is enriched because users do not need to know how to perform session transfer. However, in IMS architecture, three different network nodes (SIP forking proxy, SIP registrar and B2BUA) need to cooperate for session continuity. When single user (callee) logs in from different devices, it is very hard to achieve cooperation. In addition, these network nodes should be scalable when many users request this service simultaneously. This paper proposes a general architecture that supports the user mobility and how the general architecture can be realized into a Web-based communication system. Our initial analytical result shows that the usage of computing resources (e.g. CPU) is reduced while supporting scalability, thanks to the simple Web client service infrastructure and Web Socket connections on top of HTTP.

The evolving standards of mobile communications, the wide variety of services they offer and the rapid growth of the Internet have made a merger of the two network technologies inevitable. One of the most prominent platforms that has been developed to facilitate this is the IP Multimedia Subsystem (IMS) concept. Many mobile communications standards integrate IMS as the main core network architecture and Quality of Service (QoS) is the main concern for customer satisfaction. A major approach to optimisation of QoS is the Differentiated Services scheme, and a simulation study of implementations of this is presented. The study covered an IMS core network architecture modelled with discrete-event network simulator software, with a Differentiated Services QoS scheme run over it with differing bearer traffic scenarios. Implications for core network architectures are discussed.

IP Multimedia Subsystem (IMS) is an enabling technology that are designed to provide multimedia services over heterogeneous networks. In IMS based heterogeneous networks the placement of gateway plays a vital role in enhancing the Quality of Service (QoS) and the enhanced Packet Data Gateway (ePDG) is being considered in interworking. The ePDG is realized at the edge of the network where IP Multimedia Subsystem (IMS) interacts with Worldwide Interoperability for Microwave access (WiMAX). Also, the performance of network has been enhanced by allocating priorities to mobile Stream Control Transmission Protocol (mSCTP) on per stream basis. Hence the proposed interworking system considers the impact of IMS with mSCTP and ePDG. In this paper, the performance of the network has been evaluated in terms of throughput, delay and retransmission attempts and the performance comparison is made against the conventional Transport Control Protocol (TCP) over the same network conditions. The performance evaluation shows that the proposed QoS approach improves delivery of multimedia services over heterogeneous IP access.