Optimising Differentiated Services Strategies under IMS

Within the 3rd Generation Partnership Project (3GPP), the thrust of the session initiation protocol (SIP)-based Internet protocol (IP) multimedia subsystem (IMS) is envisaged to allow a swift progression towards the provision of multimedia applications for increasingly demanding end users. The paradigm of service programmability using open network application programming interfaces (APIs), with open service access (OSA) as its main exponent, is helping to drive this development together with the use of SIP. The focal point of this paper will be the multimedia services architecture in the IMS by providing details of the interaction of the IMS and the application servers in the form of the OSA gateway and the SIP application server. The paper aims to assess the value of the IMS service control (ISC) interface on application server interaction in the IMS. The paper will provide an OSA application use case, and will also present the presence server as an example of a SIP application server that fits in with the IMS. © 2003 Lucent Technologies Inc.

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.

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.

Quality of Service (QoS) provisioning is one of the main requirements in the 3GPP IP Multimedia Subsystem (IMS) and it has been addressed in different works since the beginning of the IMS standardization process. As a result of the fixed and mobile networks evolution, the parameters standardized in IMS have changed constantly until the specification of the Policy and Charging Control (PCC) architecture that integrates IMS QoS and charging functionalities. However, current IMS QoS specifications still have some limitations to handle service flexibility that is required to provide Internet services over IMS. In this work, we propose an enhanced IMS QoS architecture to support efficient QoS providing for flexible services with dynamic requirements. This proposal is compared against different approaches to evaluate their behavior under network saturation conditions. Simulations results show that the architecture we propose achieves efficiency and flexibility, maintaining the number of blocked and active sessions, and increasing the number of high priority sessions activated in a saturated network.

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.

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.

As the next generation networks promise network convergence with services for both static and mobile networks, the research focus is converging towards standardizing a common infrastructure for all-IP networks. IP Multimedia Subsystem (IMS) is a recent initiative, which outlines a service delivery platform (SDP) framework. A flexible and robust QoS management system for IMS is essential to ascertain the achievability of service quality on these converged networks. As Triple and Quadruple Play services are the most celebrated services of IMS in the near future, the necessity of QoS assurance is becoming an imminent need of the hour. Multimedia services delivery in converged IP networks using IMS, concentrates on ensuring capabilities to ensure the best QoS. To meet these requirements, we have designed a set-top box which provides feedback in IMS management architecture to ensure end-toend QoS as well as enables the functionalities of Regional Gateway for the Home Network. Results of the simulation confirm the improvement of performance parameters and the quality of service.

Chapter 16 - The IP Multimedia Subsystem: True Converged Communications

Implementation of Next Generation Networks (NGN) is well underway in developed countries. Focus is now on how to address issues like Quality of Service (QOS) control. This however has not been the case in countries with emerging economies which are still struggling to provide basic internet and telephone services. Broadband wireless networks present affordable communications solutions for such economies. In this paper we present a prototype NGN implementation based on Worldwide Interoperability for Microwave Access (WiMax) technology, Linux routers, an open-source IP Multimedia Subsystem (IMS) network and open-source content servers. Link quality tests show that such an implementation is capable of providing NGN services to larger community sectors. In conclusion we recommend the use of a higher throughput subscriber unit for IPTV services and incorporation of IMS capabilities in the access and core networks to achieve QoS control through resource-based admission control lacking in the WiMax access network

The emerging paradigm of network function virtualization (NFV) technology promises an efficient solution for optimized service deployment in the cloud computing environment thanks to its ability to dynamically add or remove virtual resources when there is a change in workload. Nevertheless, telecom providers are still facing a challenging issue in efficiently adopting NFV to deploy Web real-time communication (WebRTC) service on top of IP multimedia subsystem (IMS). Providing WebRTC service increases the inherent complexity of the IMS system in terms of the number of service nodes as virtual network functions (VNFs) and the way they interact, both of which play significant roles in the problem of optimally allocating resources. This paper proposes a virtualized interworking system between IMS and WebRTC called NFV-based interworking architecture, and describes the mechanism for VNFs to exchange messages with each other. We present an analytic system model considering the constraints of resources, quality of service (QoS), and service costs. A real-time Markov approximation-based resource allocation algorithm (RIDRA) is then designed allowing a provisioned resource at service nodes to be reconfigured in time to meet performance requirements. The proposed solution is evaluated on the large scale by simulation and on the small scale by our developed testbed. Experimental results reveal that our algorithm effectively responds to fluctuating service demands with a service cost reduced by 19% via efficiently allocating virtual resources while maintaining QoS requirement.

Although the IP Multimedia Subsystem (IMS) and Web Serviceshave been developed on the basis of different Service Delivery Platforms (SDP), opportunities for new services have emerged from converged access to IMS and Web Services. Researchers are focusing on finding means to develop converged access architectures for IMS and Web Services while preserving the benefits they provide and not overburdening the end users' terminals. In this paper, we classify the existing converged access methods for IMSand Web Services into four categories, compare them and identify their drawbacks. To address these drawbacks, we have designed a hybrid thin client-based novel architecture for converged access to multimedia services provided by a combination of IMS and Web Services. The proposed solution limits the impact of platform heterogeneity and resources by relinquishing the complexity of signalling and session management to an intermediate virtualization server, which in turn acts as a client for network-based services.

The 3 rd Generation Partnership Project (3GPP)'s UMTS networks promise to deliver an abundance of advanced, innovative, and feature-rich applications to end-users in a 3 rd Generation (3G) wireless environment. An IP Multimedia core network Subsystem is being introduced as part of this 3G wireless environment which aims to enable the convergence of, and access to, voice, video, messaging, data and web-based technologies for the wireless user. The goal is to combine the growth of the Internet with the growth in mobile communications. The service control architecture for the IMS can be summarised as consisting of an Application Server, providing the execution environment for the applications, and communicating with the Call State Control Function that handles the session control and mobility management functionality. Three general sets of standardised platforms for service control are being introduced in the UMTS' IMS, each one addressing particular needs, from legacy service support to light weight SIP based support. This paper aims to provide an overview of the IMS service control architecture focusing on the rational of the decisions taken in 3GPP.