IP Multimedia Subsystem Research Articles

A lightweight convergent personal mobile service delivery approach based on phone book

SUMMARYMobile phone users are demanding an efficient convergent communication approach for efficient communication and information sharing with their real life social circles. Unfortunately, the existing telecom services and the popular Internet services are not organically integrated to provide convenient convergent services. To overcome this issue, one of the promising convergent communication services considered by telecom carriers is RCS (Rich Communication Suite). However, existing issues, such as insufficient interoperability among different operators, shortage of terminals and heavy dependence on large‐scale IP multimedia subsystem (IMS) network deployment, mean that it will take time to implement RCS across worldwide networks and for it to become a service equally universal as voice and short message. Instead of a heavyweight RCS solution, in this paper, we propose a lightweight, quick deployment mobile phone book application system based on cloud computing without a fully deployed IP multimedia subsystem infrastructure, which seamlessly integrates traditional telecommunication services, instant messaging services, social networking services and automatic contact information management. Based on this, ‘Telco‐OTT’ service provision approach, telecom carriers can allow their subscribers to enjoy conveniently the rich convergent personal service experience quickly without a large initial investment. Thus, it is a low‐risk opportunity for telecom carriers to meet subscriber demand for advanced user‐centric convergent service features. Copyright © 2013 John Wiley & Sons, Ltd.

Gateway Station Architecture of Satellite Access Networks for IMS-Based Core Networks

In this paper, an architecture of gateway of satellite access networks is designed for accessing to IP Multimedia Subsystem (IMS) core networks, and the architecture of QoS is proposed to control and manage the IMS accessing QoS procedure. To reduce the delay of signaling transmission, an enhanced session initial protocol (SIP) is simplified for adapting to the satellite scenario.

Performance of CS Fallback from LTE to UMTS

Circuit Switched Fallback (CSFB) is the most commonly used method to support voice services over Long Term Evolution (LTE) networks today, as the deployment of IP Multimedia Subsystem (IMS) is still in its infancy. In this article, we discuss the performance of CSFB voice traffic redirection from LTE to UMTS using data from live commercial networks. The key factors impacting CSFB call setup delay are highlighted. Data from multiple cell geometries including stationary and mobility conditions are presented for Mobile Originated (MO) calls towards landlines, Mobile Terminated (MT) calls from landlines and Mobile-to-Mobile (M2M) CSFB calls. Analysis results in well optimized deployments show that on an average, MO/MT call-setup time for CSFB from LTE to UMTS is around 1 sec greater than legacy UMTS. However, the results can vary depending on the network configuration and the conditions of the measurement. To illustrate the optimization of CSFB performance in real networks, we also highlight the principal call set up optimization and implementation factors impacting CSFB call setup delay and success rates. This article demonstrates that in well optimized networks, CSFB to UMTS call setup success rates can be very close to those achieved in the legacy UMTS systems.

Vulnerability Evaluation of Multimedia Subsystem Based on Complex Network

IP multimedia subsystems bring huge security threats to the IMS-based next-generation networks although they bring IMS-based network integration and business ability enhancement. Therefore, the research on the vulnerability of IP multimedia subsystems attracts widespread attention recently. In this article, the security threats of next-generation core networks are discussed first. And then we analyze the vulnerability characteristics of IP multimedia subsystems. In order to evaluate the vulnerability of IP multimedia subsystems effectively, this paper further applies the complex network theory to construct the network model of IP multimedia subsystem and propose the vulnerability assessment indicator by adopting entropy model. Finally, some simulation experiments and result analysis are provided to our evaluation model. Both theoretical analysis and numerical simulations indicate that the proposed vulnerability measurement is a simple and effective new method to evaluate the overall vulnerability of this kind of IP multimedia subsystems. In addition, the proposed method provides a new idea and scientific basis for the vulnerability assessment of IP multimedia subsystems.

PTT Service Interworking Between IMS Based Networks and P2P Overlay Networks

The demand for multimedia streaming services is increasing rapidly. To meet this demand, there has been much research and many practical developments for providing multimedia services. A push-to-talk (PTT) service is one of the multimedia streaming services that have been deployed not only over IP multimedia subsystem (IMS) but also in peer-to-peer (P2P) overlay networks. The benefit of PTT has been demonstrated in the literature. However, the need for using PTT service in communication can be arbitrary among users, regardless what kind of PTT services they use. This demand does not support current PTT systems, so an expansion of PTT services still be limited. Moreover, the combination of PTT services in IMS and P2P networks will help operators to provide more scalable PTT services. Therefore, in this paper, we proposed a model to support PTT service interworking between IMS and P2P overlay networks. We also introduced our system design and some interworking service scenarios. We confirmed our architecture through implementation and testing.

Context-Aware Multimedia Distribution to Mobile Social Communities

The work here presented introduces a next generation context-aware architecture for social networking multimedia distribution. It enhances the Multimedia Broadcast Multicast Service (MBMS) and the Evolved MBMS (E-MBMS) systems by adding users’ situation knowledge on their assessments allowing Mobile Operators to offer personalized services delivered over optimized networks. Furthermore, it evolves IP Multimedia Subsystem (IMS) with specific functionalities to control the context information and to manage MBMS and E-MBMS bearers. The proposed framework was tested and the results are here presented. A clever content sharing in mobile communities can be the basis of the famous killer application that Mobile Operators are still looking for.

Open Standards, Open Innovation, and the Rollout of IMS

The Internet's open architecture has proved to be an engine of innovation. The traditional openness of the original TCP/IP protocol suite, however, is coming under pressure as broadband providers develop new network architectures that may, depending on how they are implemented, change the traditional model of without permission.1 Notably, the advent of the IP Multimedia Subsystem (IMS) has raised three questions addressed by the roundtable: (1) what is IMS and why should policymakers care about its development?; (2) what opportunities and threats do the rollout of IMS raise?; and (3) what policy concerns--related to innovation and competition--are implicated by those issues?

A generic interoperability testing framework and a systematic development process for automated interoperability testing

Interoperability is a prerequisite to allow users to access systems implemented by different vendors seamlessly. A good baseline to achieve interoperability is the implementation of a common set of standards. However, this is often not sufficient as different implementations of a standard are not necessarily interoperable. Therefore, different implementations of systems need to be assessed for interoperability by applying interoperability testing. In this article, we present a generic framework that enables automated interoperability testing with message checks, which assess the compliance of messages exchanged between systems. The goal of this framework is the provision of a basic functionality of interoperability test entities, the definition of a generic interoperability test environment, and guidelines for the specification of automated interoperability tests. The framework also considers aspects related to interoperability testing including verdicts, automation, and limitations of the system under test. Through the application of the framework, interoperability of systems can be assessed, systems can be validated, and standards can be improved. In addition, we present a systematic development process for automated interoperability tests to formalize the development and specification of an interoperability test system. We also consider aspects and critical issues, which are important for the development of a complete interoperability test system. The framework and the process are language and system technology independent. We present their application in a case study that includes interoperability tests for the Internet Protocol Multimedia Subsystem (IMS) using the Testing and Test Control Notation Version 3 (TTCN-3).

A Survey on Media Independent Handover (MIH) and IP Multimedia Subsystem (IMS) in Heterogeneous Wireless Networks

One challenge of wireless networks integration is to provide ubiquitous wireless access abilities and seamless handover for mobile communication devices between different types of technologies (3GPP and non-3GPP), such as Global System for Mobile Communication, Wireless Fidelity, Worldwide Interoperability for Microwave Access, Universal Mobile Telecommunications System and Long Term Evolution. This challenge is critical as mobile users are becoming increasingly demanding for services regardless of the technological complexities associated with them. To fulfil these requirements for seamless vertical handover (VHO) two main interworking frameworks have been proposed by IEEE Group and 3GPP for integration between the aforementioned technologies; namely, Media Independent Handover IEEE 802.21 and IP Multimedia Subsystem, where each of them requires mobility management protocol to complement its work, such as Mobile IP and Session Initiation Protocol, respectively. Various VHO approaches have been proposed in the literature based on these frameworks. In this paper, we survey the VHO approaches proposed in the literature and classify them into four categories based on these frameworks for which we present their objectives and performances issues.

IMS-based distributed multimedia conferencing services for next-generation mobile networks

Distributed architecture offers many advantages compared to centralized architecture in terms of providing multimedia services. However, as a trade-off, distributed architecture requires that peers contribute a portion of their bandwidth and computational capacity to maintain the mutual overlay interconnection. This requirement develops into a serious problem for mobile users and wireless infrastructure, as the radio resource in this network is tremendously expensive, based on 3gpp (2005), and is one of the reasons why distributed architecture has not been widely applied in next-generation (4G) networks. It is also the main reason why multimedia services such as video conference have to rely on a costly centralized architecture built over an expensive media resource function controllers via the Internet protocol (IP) multimedia subsystem (IMS). This research work proposes a new distributed architecture utilizing intelligence and extra capacity, currently available on LTE and WiMAX base stations to reduce the required bit rates that each peer has to provide in order to maintain the overlay network. This reduction saves valuable radio resources and allows a distributed architecture to provide video conferencing services on 4G networks, with all the advantages of a distributed architecture such as flexibility, scalability, smaller delay, and lower cost. In addition, this can be implemented with a minimum modification of the standardized IMS platform and the 4G infrastructure, thereby saving the operators and service providers from excessive investments. A prototype has been built to prove the feasibility of the proposed architecture and evaluate its performances. The results show that our proposed distributed video conferencing service can actually reduce the average bandwidth required for data and signaling messages at wireless mobile terminals while maintaining the main operations of a video conference session.

Evaluation of the Extended CBD Model: A Case Study using IMS Application

A large number of projects failed because of concentrating on developing new software. The Main drawbacks of new software development are more costly, and need maintenance. Reuse is solution of these problems that caused the widespread usage of object oriented (OO) development. Object oriented development is the backbone of component-based development (CBD). CBD facilitates reuse of the existing components (by customizing) with the new ones. Main advantages of reusable components are more reliable, saved time and reduced cost. CBD approach is different from traditional/new software development. Several models have been proposed for traditional software development such as Waterfall, Rapid Application Development (RAD), Evolutionary, Rational Unified Process (RUP) and agile. Whereas the popular CBD models, for customized development, are V, Y, Umbrella and W. Almost all software development companies, both the new software and customized software have to be developed. Therefore majority of the software development companies face problem to select and implement an appropriate process model for the both kinds of developments. To address this problem, the existing RUP and CBD models do work to some extent but the authors intend to propose an extended CBD model that it equally offers its benefits for new and customized developments. The experimental data is taken from a case study to develop IP Multimedia Sub System (IMS)-based examination application using iPhone to evaluate the proposed model. The results provide evidence that the extended CBD model can be equally beneficial for the development of both new and customization components for IMS-based applications.

A Formal Data-Centric Approach for Passive Testing of Communication Protocols

There is currently a high level of consciousness of the importance and impact of formally testing communicating networks. By applying formal description techniques and formal testing approaches, we are able to validate the conformance of implementations to the requirements of communication protocols. In this context, passive testing techniques are used whenever the system under test cannot be interrupted or access to its interfaces is unavailable. Under such conditions, communication traces are extracted from points of observation and compared to the expected behavior formally specified as properties. Since most works on the subject come from a formal model context, they are optimized for testing the control part of the communication with a secondary focus on the data parts. In the current work, we provide a data-centric approach for black-box testing of network protocols. A formalism is provided to express complex properties in a bottom-up fashion starting from expected data relations in messages. A novel algorithm is provided for evaluation of properties in protocol traces. Experimental results on Session Initiation Protocol (SIP) traces for IP Multimedia Subsystem (IMS) services are provided.

Traffic Model of IMS/NGN Architecture with Transport Stratum Based on MPLS Technology

Abstract Growing expectations for a fast access to information create strong demands for a universal telecommunication network architecture, which provides various services with strictly determined quality. Currently it is assumed that these requirements will be satisfied by Next Generation Network (NGN), which consists of two stratums and includes IP Multimedia Subsystem (IMS) elements. To guarantee Quality of Service (QoS) all NGN stratums have to be correctly designed and dimensioned. For this reason appropriate traffic models must be developed and applied, which should be efficient and simple enough for practical applications. In the paper such a traffic model of a single domain of NGN with transport stratum based on Multiprotocol Label Switching (MPLS) technology is presented. The model allows evaluation of mean transport stratum response time and can be useful for calculating time of processing requests in the entire NGN architecture. Results obtained using the presented model are described and discussed. As a result of the discussion, elementary relationships between network parameters and transport stratum response time are indicated.

Research of SIP Compression Based on SigComp

SIP (Session Initiation Protocol) has been chosen as the core signaling protocol of the NGN (Next Generation Network), but the large SIP message which is text-based is an obstacle with the planned usage of SIP in wireless mobile networks. Based on the SigComp (Signaling Compression) framework, some further improvements are made to the Deflate algorithm according to the characteristics of SIP in this study. Experiments show that the improved Deflate algorithm can compress the SIP message greatly and reduce the bandwidth requirements signally, so it is highly valued in IMS (IP Multimedia Subsystem), PTT (Push To Talk) and other wireless real-time SIP applications.

Semi-Markov models for performance evaluation of failure-prone IP multimedia subsystem core networks

Next generation telecommunication core networks are typically based on the Third Generation Partnership Project Internet protocol (IP) multimedia subsystem (IMS). Their planning and deployment must take into account the occurrence of random failures causing performance degradations, in order to assess and maintain a high level of quality of service. In particular, IMS signalling servers can be modelled as repairable multi-state elements where states correspond to different performance levels. This article provides an evaluation of IMS signalling network performance in long runs in terms of two metrics adopted in the practice, such as the number of call set-up sessions that the network can manage at the same time and the call set-up delay. A semi-Markov model has been adopted for the IMS servers, which allows as well for non-exponential probability distributions of sojourn times, as often observed in real networks. Furthermore, a redundancy optimization problem is solved in an IMS-based realistic scenario, to the aim of minimizing the deployment cost of a telecommunication network with a given availability requirement.

IMS에서 효율적인 NAT Traversal 해결 시나리오

IP 주소 공간의 부족 문제를 해결하기 위해 NAT(Network Address Translation) 기술을 활용할 수 있다. NAT의 주소 변환 테이블에 없는 바인딩과 관련된 패킷을 제거하는 필터링 특성 때문에 NAT Traversal 문제가 발생한다. 이러한 문제를 해결하기 위해 부가적인 장비를 활용한 여러 가지 방법들이 제시되었다. 최근의 네트워크 시장은 유선과 무선이 통합되는 형태로 발전하고 있으며, 이를 효과적으로 제어하기 위하여 IMS(IP Multimedia Subsystem)라는 유무선 통합 제어 망이 등장하였다. IMS에서 IBCF(Interconnection Border Control Function)와 IBGF(Interconnection Border Gateway Function)라는 부가적인 장비를 이용하여 NAT Traversal 문제를 해결하고 있다. 본 논문에서는 P-CSCF(Proxy-Call Session Control Function)를 활용하여 부가적인 장비를 사용하지 않고 NAT Traversal 문제를 해결하는 방안을 제안한다. We can use NAT(Network Address Translation) technology to solve the lack of IP address. The problem of NAT traversal is happened when the filtering characteristics of NAT remove the packet that has no binding in the address translation table of NAT. There were many kinds of way to solve these problems by using additional device. Lately, network market is changed into integrating wired and wireless network by the IMS(IP Multimedia Subsystem). The IMS integrates to control network of wired and wireless network, has emerged to control convergence network effectively. Lately, the additional devices like IBCF(Interconnection Border Control Function) and IBGF(Interconnection Border Gateway Function) are used to solve the NAT traversal problem in the IMS. In this paper, we propose the solution of NAT traversal using P-CSCF without any additional equipment in the IMS.

A Parsing Mode based Method for Malformed SIP Messages Testing for IMS Network

IMS(IP Multimedia Subsystem) network uses SIP (Session Initiation Protocol) as its core control protocol. The defensive ability of the malformed SIP message is particularly important for IMS network security. In this paper, we propose a malformed SIP generation method based on SIP parsing mode and the associated attack testing method. Based on SIP parsing mode of functional entities in IMS, we generate effective malformed SIP messages, which then be used to perform attacking test to IMS functional entities by establishing different session models, so as to evaluate the defensive ability of these entities and provide recommendations for improving the security of the IMS network. We generated a set of malformed SIP messages through this method and apply them to the attacking test of the well-known IMS testbed OpenIMSCore under different session models. The testing finds new vulnerabilities in OpenIMSCore, which shows that our method of malformed SIP messages generation is effective.

Policy and Charging Control for Virtual IMS Client

In its latest releases, the IP multimedia subsystem (IMS) service model provisions Quality of Service (QoS) and enforces charging through its policy and charging control (PCC) architecture. By exploiting the intrinsic segregation of the signalling and media planes that the IMS service model offers, a virtual IMS client could be developed that simplifies terminal device implementation by offloading signalling and session management tasks to a remote server. In this paper, we study how the IMS/PCC architecture can be deployed in conjunction with a virtual IMS client. Although a virtual IMS client assigns the signalling tasks (accomplished through session initiation protocol and session description protocol) to a remote server, information related to QoS should be propagated back to the access network and also the end user's terminal device. Therefore, designing a virtual IMS client that only deals with the media plane is challenging. In this paper, we propose a PCC architecture for the virtual IMS client that keeps the end user's terminal as simple as possible while providing the necessary functions of the IMS/PCC architecture. Since QoS provisioning is access network specific, we explore the proposed architecture for two predominant networks access methods: UMTS from 3GPP and WLAN from IP-based access.

IP Multimedia Subsystem?An Intrusion Detection Systeme

The IP Multimedia Subsystem (IMS) amalgamates the core of telecommunication and Internet protocol (IP) network access to ease network traffic of the next-generation network (NGN). Since the coalescence of the NGN, malicious attacks can also disrupt multimedia services. This can lead to financial loss for telecom operators and loss of connection for users. This paper introduces an attack detection schema (ADS) that provides security from session initiation protocol (SIP) flooding attacks. The proposed schema is configured with the OpenOpenIMSCore to validate the accuracy of SIP session traffic. Similarly, the schema is imbedded with the OpenIMS client, which helps to detect and expose such attacks on the IMS client display. Since even a small flooding attack could clog the OpenOpenIMSCore, detection accuracy should be relatively higher to prevent OpenIMSCore from going down. The proposed schema includes a key authentication schema for proficiently analyzing SIP packets. The proposed authentication is placed between the transport and application layers. A network traffic tool, Ntop, is configured with the OpenOpenIMSCore to analyze SIP traffic, Real Time Transport Protocol (RTP) traffic and the throughput rate. Overall, the proposed schema of ADS improves reasonably well after it cuts off the attacker.

A Method for Disguising Malformed SIP Messages to Evade SIP IDS

Malformed SIP attacks are threatening the security of VoIP system, such as IP Multimedia Subsystem, which uses SIP (Session Initiation Protocol) as its core protocol. Though IDSs (Intrusion Detection System) supporting malformed SIP detection had been produced, it was not clear to what extent they can detect disguised malformed SIP messages. This paper analyzes the condition of SIP IDS evasion and proposes a method for disguising malformed SIP messages. Based on the disguising method, a testing system is built for evaluation the capability of SIP IDS on evasion defending. The result of the experiments show that the proposed method can improve the evasion rate of malformed SIP messages considerably, which means the defending capability of SIP IDSs should be improved to prevent them from evasion.