Relevance of SDK to foster IMS application development

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.

Today's IP Multimedia Subsystem (IMS) client on a mobile device provides basic services, including voice, presence, messaging, and contact management. In the future, the IMS client should be prepared to handle a large variety of innovative and unexpected services that integrate into the client seamlessly among existing services. Bell Labs' Client/Service IMS Architecture group has defined a product concept called API for Mobile IMS Client Application (AMICAL) that provides multiple levels of application programming interfaces (APIs) for third parties developing IMS-enabled applications. By using a plug-in framework, AMICAL allows users to enhance the IMS client with innovative features without modifying the proprietary core software. At another level of abstraction via an IMS kernel service, third party developers can write their own application completely independently of the IMS client, yet enable it with IMS features such as presence-enabled objects and easily deployed communication services. These components provide a demonstrably effective means to promote new and innovative IMS-enabled services and applications by third party developers.

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.

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.

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).

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.

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.

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 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.

Emergency Telecommunications (EMTEL) deal with provisioning of telecommunications services in emergency situations; these can range from an individual in a state of personal emergency (with need to make an emergency call due to sudden illness, traffic accident, fire) to a very broad perspective of serious disruptions (earthquakes, floods, terrorist attacks). EMTEL covers the telecommunications needs of public safety resources, like: police, fire–fighters, ambulances and other medical services: such services usually rely on dedicated networks and equipment. We realised PICO (control platforms and delivery of services in converged networks) a platform for service delivery and emergency management on public telecommunications networks. PICO platform leverages on application streaming on Android OS and a context–aware system for fixed–mobile convergence based on IP Multimedia Subsystem (IMS).

IMS (IP Multimedia Subsystem) presents a variety of services and features to meet the needs and expectation of subscribers. This variety of choices presents risks of retrieving non oriented services while responding to subscriber request. This may be due to similarities between services and to the huge amount of available services. In addition to service information, it is possible to extract and explore subscriber information in IMS network. Thus, it becomes interesting to consider, besides of request details, subscriber profile information in service discovery process. This paper presents an overview of our model and its mechanism based upon IMS architecture which provides service discovery combined with proactive service exposure to better respond to subscribers' needs and expectations. The results show improvement of usual state of the art models on several axes.

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.

The IP multimedia subsystem (IMS) standard is being widely adopted by both wireline and wireless service providers to support the next wave of multimedia communication applications. As currently defined, that IMS standard proposes a detailed architecture for the transport and control layers of the next-generation telecommunication networks, but leaves many questions unanswered on how the application layer should be structured. A more structured approach to service delivery will be required in order to deliver new multi-media applications in an efficient and cost-effective way. An approach based on service delivery platform (SDP) proposes a layered service architecture, with a strong emphasis on re-use of common service enablers and on open APIs. This paper describes work being undertaken within HP's IMS Experience Center to validate a horizontal service delivery architecture for next-generation IP multimedia applications.

International audience