تجزیه و تحلیل عملکرد از خدمات چند رسانه ای طرح اصلی یا نمونه در شبکه هوشمند باند پهن

Advanced multimedia multiparty services call for sophisticated signalling systems able to manage multiple parties and media in broadband environments. In this paper we dealt with the support of multimedia applications in an Intelligent Broadband Network (IBN), where the Intelligent Network, in a closed interaction with the B-ISDN, furnishes control functionality to handle complex service configuration. Some different options for an IN/B-ISDN interaction are discussed starting from the results of the INSIGNIA project (carried out in the framework of the European Union ACTS program) where a prototypal IBN system has been specified and developed in a field trial. Two main architectural solutions are discussed and a generic modelling methodology for the performance analysis of the control plane is presented. The objective of this modelling methodology is to provide insights into the behaviour of the system under dynamic conditions and to capture the influence of alternative functional settings. The proposed model is applied to the evaluation of the support of the Broadband Video Conference service in the prototypal system as well as to compare the performance of alternative architectural solutions for the IBN.

The provision of advanced multimedia and multiparty services represents a very attractive goal for the telecommunication industry. These sophisticated services require a wide range of capabilities both in the transport and in the control plane of the network. In this paper we dealt with the integration of the Intelligent Network (IN) paradigm with the B-ISDN as a possible solution for the support multimedia–multiparty services. The proposed approach, indicated as Intelligent Broadband Network (IBN), has been investigated in the framework of the European ACTS project named INSIGNIA [1] and [2] (IN and B-ISDN Signalling Integration on AMT platforms) where a complete architectural solution has been defined, implemented and validated in field trials over a PAN-European ATM network. In the IBN system the Asynchronous Transfer Mode fulfils the customer requirements at the broadband transport level while the Intelligent Network provide a powerful signalling system able to control and co-ordinate the multiplicity of B-ISDN calls required to build the whole service configurations. The INSIGNIA architectural model is based on the concept of “Session” and it allows the IN to manage multiple parties and bearer connections and to realise sophisticated Service Logics for the deployment of broadband multimedia applications. The advantage of the proposed approach resides mainly in the flexible service creation environment offered by the IN and in the opportunity to introduce, in a very short term and with a high degree of transparency with respect to the underlying signalling platform, new telecommunication services. This flexibility allows network operators to upgrade their systems easily and in a cost-effective manner by taking advantage of the ability to allocate, without restrictions, control functionality and resources within the network. In this paper we describe the support of the Broadband Video Conference (B-VC) service in an IBN system and we present two different functionality settings that allow the handling of a fully meshed interconnection among multiple parties for the exchange of audio and video flows [2], [3] and [4]. The first setting refers to the architecture defined in the INSIGNIA project while the second one enhances such architecture by introducing the capability to realise multi-sessions services. In the IN/B-ISDN environment, services, like the B-VC one, are described by a set of distinctive characteristics that are implemented by different functional entities distributed in various network elements. Therefore the functional entities of network elements serve more than one service and one service is served by more than one functional entity. As a consequence a suitable realisation of the IN functionality into different architectural settings becomes a dominant factor to allow the most efficient operation of the system itself. We propose here an analytical and simulative modelling tool that allows to: • evaluate the system performance in a wide set of conditions; • dimension the system parameters so as to achieve a suitable load balancing that, by avoiding bottlenecks, improves the overall efficiency and the user perceived performance; • highlight the key performance pros and cons of different architectural alternatives. The performance evaluation is focused on the derivation of design guidelines to engineer the “intelligent level” of the network to reach efficient resource utilisation and to guarantee the quality of service parameters required by the users [5], [6] and [7]. The proposed model captures the main aspects related to the complexity of the service realisation by exploiting signalling interactions at both the IN and B-ISDN level. The overall performance methodology is applied to the evaluation of the prototypal signalling system developed in the context of the INSIGNIA project by showing the impact on that system of the proposed architectural alternatives. One of the main results of the analysis is the processing times dimensioning so as to achieve uniform resource utilisation of the system functional entities. Moreover, the analysis of the selected performance metrics allows a comparison among alternative architectures by highlighting the system bottlenecks and the most critical performance parameters such as the delay encountered in each functional entity and the overall service set-up and tear down delay perceived by end-users. The organisation of this paper is the following: Section 2 gives a brief overview of the IBN concept as defined in the INSIGNIA project. In Section 3 we present two architectural solutions for the IN/B-ISDN integration. In Section 4 we describe how to deliver a Video Conference service in an IBN system and the relevant Information Flows among network functional entities. The model for the performance evaluation of the IBN system is introduced in Section 5 and applied to the performance analysis of the prototypal system (6.1 and 6.2) and to the comparison of alternative architectural solutions (Section 6.3). Section 7 derives the conclusions and indicates guidelines for the design of an Intelligent Broadband Network

In this paper we investigated some key architectural and performance issues for the support of a multimedia–multiparty service in an Intelligent Broadband Network scenario. We addressed the architectural model derived in the framework of the ACTS INSIGNIA project to support new telecommunications service by means of the integration between the IN and the B-ISDN. In this context we proposed two architectural alternatives for such IN/B-ISDN integration: 1. The “Single Session” solution (in accordance to the INSIGNIA approach) based on a single Session, opened in one B-SSP, to allow the B-SCP to handle the service instance. 2. The “Multiple Sessions” concept that allows the Service Logic to distribute the bearer connection co-ordination among several B-SSPs. The paper is then dedicated to the dimensioning and to the performance analysis of the control plane. We introduced a modelling methodology aimed at evaluating the main effects of the architectural alternatives on the system performance. The proposed model is an open network of queues, based on the functional specification of the IBN system. This model is used for both analytical and simulative evaluations of the system and it allows to dimension the system parameters of each architectural alternative so as to achieve a suitable load balancing and to highlight the key performance pros and cons of alternative functionality realisations. As far as the signalling load is concerned, our results highlight that the “Multiple Sessions” approach entails a significant saving of the B-ISDN signalling, due to a considerable reduction of the signalling information exchanged at the NNI (equal to about 23% less than in the “Single Session” case). The “Multiple Sessions” approach attains better performance also with respect to the B-VC release delay. This result is justified by considering that the “Multiple Sessions” approach allows to close down the conference in a parallel manner and thus improves the system performance. This result has suggested the possibility of further enhancing the performance by performing also the establishment phase of the service in a parallel manner. Finally, it should be considered that the “Multiple Sessions” approach is always very cost-effective with respect to the “Single Session” one, as far as the transport resource utilisation is concerned. The “Multiple Sessions” approach allows some service connections to remain bordered in a specific area of the network. As a counter part, the handling of the distributed solution implies a limited increase of the total IN signalling load (about 2%) and more processing capability on the part of the SCF, since the latter has to handle a multiplicity of Sessions in the context of the same service instance.