Congestion avoidance in S-CSCF selection in an IMS network

IP Multimedia Subsystem (IMS) network peering is a key enabler that will help accelerate deployment of next-generation IMS-based networks. Today's early deployments of dispersed IMS networks require public switched telephone network (PSTN)/public land mobile network (PLMN) bridges for network interconnection between IMS islands. The PSTN/PLMN bridging arrangement is inefficient, however, in that it results in unnecessary settlements for the carriers. It further impedes the implementation of rich multimedia and Voice over IP (VoIP)-related services that require end-to-end Internet Protocol (IP) connectivity. Last, it perpetuates the reliance on the existing PSTN/PLMN network for voice calls among subscribers served by different IMS-based carriers. This paper analyzes in detail the IMS peering challenges from the perspective of Session Initiation Protocol (SIP) signaling peering. It discusses issues related to the routing of SIP messages, and addressing, address resolution, and discovery of peering points for IMS signaling peering. It further establishes that a new routing algorithm is needed that will allow signaling peering points to dynamically discover the “best” transit network among others for reaching a destination. In closing, it presents a high-level IMS signaling routing process that includes, among other benefits, support for number portability as a key function for inter-carrier IMS peering.

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.

In mobile networks, hand over refers to the process of transferring a communication from one cell to another considering the power levels of the signal and latency values. In LTE (Long Term Evolution), base stations are able to perform handover by using the X2 interconnected interface. To provide voice call over LTE (VoLTE) using a packet-switch network, an IMS (IP Multimedia Subsystem) network is also deployed. The main contribution of this work is the analysis of power consumption of a Device under Test (DuT) during intra-cell handover procedures for a VoLTE call. Empirical results show the energy consumption along the different stages of the communication between the DuT and the base station. In addition, jitter and throughput values are assessed during the intra-cell handover process. The highest power consumption was obtained during the hand over procedures and as expected, jitter values increase too. Empirical results provide key points for energy efficiency improvements.

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.

Distributed intrusion detection scheme for next generation networks

The IP Multimedia Subsystem (IMS) has been considered to be exclusive to big players of the telecommunication world. Session Initiation Protocol (SIP) has been standardized by IETF and solutions based on it have been in the market at least for a decade. It is also an essential part of the IMS, as it is the control protocol of IMS. Recent development of the Linux platform and the Open source IMS system has lead to a situation where the IMS is also an affordable solution for smaller telecommunication companies. The obvious question has been whether the level of performance with Open source IMS is really suitable for business usage. ETSI-TISPAN has unified IMS performance measurements by defining a common framework which to follow in measurements. The paper presents comparisons between IMS and SIP based networks in call and messaging performance. the Open IMS solution by the Fraunhover Focus Institute is compared with the OpenSIPS, an open source SIP server. The number of users in our measurements was chosen to be 100 000, a large enough number to be considered as a suitable number of users for small or moderate business usage needs. Our study shows that both of the systems are able to handle this many users and, in the case of OpenSIPS, with a clear margin. It was also discovered that both systems are reliable and are suitable for small and moderate business usage.

The IP Multimedia Subsystem (IMS) in all-IP based next generation communication environment can offer network/service providers various multimedia services (e.g.,voice, audio, video and data etc). The IMS is worthy of notice in that it is possible to make wired/wireless convergence and quick service development. The IMS needs an efficient Session Initiation Protocol (SIP)-based routing among Call Session Control Functions (CSCF) in charge of call and session processing. In this paper, we propose a dynamic routing algorithm for managing CSCF agents using management system based on Fault, Configuration, Accounting, Performance and Security (FCAPS) in the IMS network.

The IP multimedia subsystem (IMS) is an architectural framework for delivering multimedia in IP network. However, the IMS is less clear regarding the monitoring of performance and fault management; beside the new generation operations systems and software (NGOSS) system manipulate QoS based assurance scenarios with enhanced telecom operations map (eTOM), which describe all management operations for system level monitoring and management (SLM&M), but this specification is generic. In this article, we propose a design of SLM&M, which integrates new technologies in network management, such as WSOA for communication and data processing as business processes; and BPEL to orchestrate the monitoring operation. The first scenario of SLM&M is to monitor supply scenario of multimedia service in IMS network, which is necessary to collect management information. This information leads to the SLM&M to monitor the network behaviour after delivery. In this work, we examine the response time in information collection operation during supply.

To determine the potential signaling traffic reductions, the session establishment procedures are investigated. The investigation shows that, the S-CSCF (Serving Call Session Control Function) is the major bottleneck in IMS (IP Multimedia Subsystem) and the existing 3GPP (the 3rd Generation Partnership Project) Service Triggering Algorithm (3GPP STA) increases largely the end to end session setup delay. To reduce the session setup delay and improve the system performance, a new Group based Service Triggering Algorithm (GSTA) is proposed. And then the modeling of 3GPP STA and GSTA are presented. Theoretical analysis and simulation results show that, GSTA can efficiently reduce the signaling traffic load of the S-CSCF, increase the throughput of the system and considerably reduce the session setup delay, improve IMS network quality of service.

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.

Unlicensed, nondedicated and nondeterministic computer access networks are included in IP multimedia subsystem (IMS) in addition to the operator core network, which arises new end-to-end quality-of-service (QoS) issues for multimedia streaming. The resource availability of the network and the end-devices change drastically during a single multimedia session, which may cause a significant degradation in the overall user experience. In this paper, a multimedia content and quality adaptation framework depending on resource availability signalling over session initiation protocol (SIP) is proposed as a solution to this problem. Availability of network resources (e.g. bandwidth, buffer space) and end-device resources (e.g. battery, CPU, memory, storage) during a session is monitored and signalled over the network in real-time by the resource managers residing at both ends of the session. This framework is compliant with the IMS standard and is implemented as a plug-in.

The performance of signaling protocols in circuit and packet switching networks is a significant parameter to evaluate the performance of any telecom operator. Today, users demand continuous high data rate, service availability, network reliability, mobility, QoS and minimum service initialization time. IP Multimedia Subsystem (IMS) standardized Session Initiation Protocol (SIP), which categorize as a signaling protocol for management and maintenance of new multimedia IP-based services. Session setup time for the interactive and real-time application has become major QoS parameter to assess the performance of these applications. In the context of this communication application, in this paper, we analyze the performance of session setup time of SIP protocol over IMS network with different access networks (GSM, WLAN and PSTN). We measure and compare mean delay of each SIP message during session setup over these access networks. We also measure the mean delay with respect to distance of nodes in the network. Our results show that SIP message size, processing, transmission, queuing delay, transition from packet to switched network, node mobility and wireless channel have a consequence on the reliability, performance and efficiency of the protocol.

IP Multimedia Subsystem (IMS) is a platform for service provisioning over IP networks, standardized by 3GPP. One of the key concepts of this technology is service enablers. Enablers are reusable modules encapsulating certain network functions, in order to simplify the development of new network services. In this paper, we present GroupManager, an enabler for group management that provides improved access interfaces for multi-user applications. This enabler, based in OMA’s XML Document Manager (XDM) can be configured and accessed manually, from a web browser, or automatically, using Web Services or Java interfaces. We also describe two new enablers that take advantage of GroupManager’s features: a group-based system for establishing videoconferences, and a document repository for multimedia sessions. Finally, we show a real service developed with these modules, consisting on a multi-user communication system for professional environments.

Convergence of the emerging IP Multimedia Subsystem (IMS) includes unlicensed, nondedicated and nondetemzinistic, hence uncontrollable computer access networks for IP multimedia services. It enables provision of resource demanding real-time sewices and multimedia communication raising new end-to-end Quality-of-Sewice (QoS) challenges, for which quality adaptation using resource management is proposed as a solution in this paper: This is an integrated solution taking both IMS and computer access networks into account as well as the two end-devices and the application sewers (AS) involved in communication. The best user experience is targeted under real-time variation of available network (e.g. bandwidth, buffer space) and end-device (e.g. battery, CPU, memory, storage) resources throughout a session. The multimedia content is dynamically adapted to$t the resource availability variations, achieving maximum system (i.e. network and end-devices) resource utilization and enhanced QoS. The resource availability update signalling is carried over Session Initiation Protocol (SIP) during the session. This is work in progress.

Inter-working between SIMPLE and IMPS