IP-based access networks for broadband multimedia services

The increasing demands of new services and applications are pushing for drastic changes in the design of access networks for residential and SOHO users. Future access networks will provide full service integration, resource sharing at the packet level, and QoS support. It is expected that using IP as the base technology, the ideal plug-and-play scenario, where the management actions of the access network operator are kept to a minimum, will be achieved easily. In this article we start by giving a historical perspective of the evolution of access networks. We then describe an IP-based architecture targeted for integrated support of broadband multimedia services, designed to be low-cost and easily manageable. We illustrate the different phases of a multimedia Internet access session, when using SIP for session initiation, COPS and DIAMETER for QoS policy management, and AAA and RSVP for resource reservation.     

Requirements for B-ISDN signalling — broadband services

The broadband ISDN (B-ISDN) is being tailored to become the universal (standardised) future netowrk, and will be capable of supporting a wide range of multimedia, multi-party applications. It is based upon the same principles as its narrowband predecessor and hence can be regarded as a natural extension of it. However, the move away from constant bit rate circuit switching towards the use of asynchronous transfer mode (ATM) technology has provided much needed flexibility, especially in terms of the connection bandwidths and quality of service available to the user.This paper briefly describes the network capabilities that B-ISDN should support and how they have been derived from a representative sample of user applications principally proposed by ITU-T/ETSI and Digital Audio-Visual Council (DAVIC). The identification of the required network capabilities is the first step towards the specification of signalling protocols for the B-ISDN which must be flexible enough to support the wide range of current and future advanced applications and services. One such potential future B-ISDN application, which demonstrates the range of signalling functionality required, is the 'Travel Agent Service' which is treated in detail.     

Design for performance of broadband signalling and services

As the telecommunications industry evolves, and broadband services start to arrive, customers are increasingly coming to expect the perception of instantaneous access to service providers, together with transparency to network failures. System performance dictates that response times need to be minimised, sufficient redundant capacity be installed in case of failure, and controls be embedded within the design to manage the exceptional situations (such as media-stimulated events) that continually threaten network integrity. A vital part of this system is the broadband signalling network, which underpins the dialogue with the customer, and which enables the delivery of the service. Network design based on a 'top-down', 'end-to-end' methodology plays a fundamental role in delivering solutions that meet customers' performance needs. Simple, approximate performance models at an early stage in this life cycle are valuable to uncover major performance problems which affect the design of the architecture. Performance issues identified can then be fed back into the design process in an iterative way, to ensure that the design solution will conform to performance requirements.This paper outlines performance studies of a number of design scenarios for providing broadband services. These studies consider interactive multimedia services, looking at service demand, physical network topology, signalling message flows, the mapping of functional entities to physical components, and routeing, as part of the network design process. The most significant performance issues identified relate to bottle-necks, capacity requirements, and load-dependent response times as perceived by the customer.     

A TDMA satellite communication system for ISDN services

The authors propose a TDMA (time-division multiple-access) satellite communication system suitable for both basic and primary ISDN services in addition to B-channel transmission lines among ISDN switches. To provide these services economically and efficiently, the proposed system uses an offset quadrature phase-shift keying (QPSK) burst model coupled with high-coding gain and rate-forward-error correction, demand assignment technology for each data burst, and a transmission and reception transponder (carrier) hopping scheme. To realize cost-effective transmission and subscriber lines and to increase the reliability of TDMA terminals, the major functions of TDMA terminals have been implemented in large-scale integrated circuits (LSICs), monolithic ICs (MICs) and hybrid ICs (HICs). The experimental results show narrow spectrum transmission with little bit error probability degradation for the offset QPSK burst modem and perfect operation of demand assignment and carrier hopping capability of the system     

New directions in signaling for broadband ISDN

User networks signaling is considered. The evolution of signaling protocols is outlined, analyzing the forces producing changes in the past. Emerging broadband switching technologies and services are discussed, emphasizing capabilities that might be required. A conceptual model for representing integrated-services digital network (ISDN) calls is presented as the basis for structuring a more flexible signaling protocol to meet the needs for a broadband environment     

Common channel signalling system number 7 for ISDN and intelligentnetworks

Various functional parts of signalling system number 7 and the underlying concepts are described. The unique attributes of the lower and higher functional layers are discussed. Applications of signaling system number 7 for call control and for transaction services are presented. The signaling transfer point makes signalling networks possible. Using the lower layers of the protocol, it provides routing capability for signaling messages between the exchange offices and access of these exchange offices to the network databases. The author discusses the performance parameters associated with the signalling transfer point and examines its implementations     

AMUSE: advanced broadband services trials for residential users

The AMUSE project in the framework of the ACTS program sponsored by the European Union, has answered various questions related to the implementation and provisioning of new multimedia services. The means to pursue such objectives has been the setup and operation of small-scale trials in various European countries, involving real residential users. The article first presents the project as a whole. Then the focus is moved to evaluation of the different technologies experimented with in the field. AMUSE services have been supplied in the context of trial islands characterized by different access network typologies. Validation of the different access technologies and results coming from their installation, integration, and operation have represented a major objective of the project. Although it is very difficult to highlight particular outcomes from the technical experiments, with so many technologies put in place, some general indications emerging from the deployment of some of these technologies are supplied. Emphasis is then put on the facts and findings resulting from the activities performed in the Italian trial island, where interactive services, including fast Internet access from PCs or STBs, Internet TV style, and switched video broadcasting services have been offered. The article concludes with a summary of the major lessons learned from the trials and the identification of a number of key factors of success for interactive multimedia     

A pipelined, multiprocessor architecture for a connectionlessserver for broadband ISDN

The direct provision of connectionless service in BISDN calls for servers that are connected to or are part of an ATM network to provide the routing function at input speeds up to 622 Mb/s. Routing is achieved in such a server by changing the VCI/VPI headers in the ATM cells; actual switching is done by existing switches in the ATM network. The paper presents an architecture capable of executing all the functions of a server at input speeds up to 622 Mb/s, scalable to multiple inputs at that speed, making use of processors and special hardware that are available today. To avoid storing large quantities of data, the architecture routes data packets by examining routing information in the initial cell of the packet and routing subsequent cells as they arrive rather than waiting until the complete packet has arrived. It is capable of handling packets that have been multiplexed at the SAR sublayer using AAL Type 3/4 and, with minor modifications, could also handle Type 5 traffic. Arguments are also presented for the use of AAL Type 5 for the direct connectionless service     

A proposal of an ATM wireless access system for tetherless multimedia services

This paper proposes an ATM wireless access system for tetherless multimedia services. The proposed system is intended to provide ATM-based high-speed transmission capability for tetherless multimedia services by wireless media in private LAN/WAN environments as well as public environments. To enable high-speed transmission, this paper proposes the utilization of the SHF band taking advantage of its wide frequency spectrum availability. However, the propagation feature of the SHF band limits the wireless terminal mobility in the proposed system compared with current cellular phone systems. This paper discusses the concept and system architecture of the proposed ATM wireless access system, including its ATM transport based on ATM/TDMA conversion using a time stamp scheme.     

A broadband multimedia collaborative system for advancedteleradiology and medical imaging diagnosis

This paper presents a new telemedicine system currently in routine clinical usage, developed within the European Union (EU) ACTS BONAPARTE project. The telemedicine system is developed on an asynchronous transfer mode (ATM) multimedia hardware/software platform comprising the following set of telemedicine services: synchronous cooperative work, high-quality video conference, multimedia mail, medical image digitizing, processing, storing and printing, and local and remote transparent database access. The medical information handled by the platform conforms to the Digital Imaging and Communications in Medicine (DICOM) 3.0 medical imaging standard. The telemedicine system has been installed for clinical routines in three Spanish hospitals since November 1997 and has been used in an average of one/two clinical sessions per week. At each clinical session, a usability and clinical evaluation of the system was carried out. Evaluation is carried out through direct observation of interactions and questionnaire-based subjective data. The usability evaluation methodology and the results of the system usability study are also presented in this article. The experience gained from the design, development, and evaluation of the telemedicine system is providing an indepth knowledge of the benefits and difficulties involved in the installation and clinical usage of this type of high-usability and advanced multimedia telemedicine system in the field of teleradiology and collaborative medical imaging diagnosis     

Smooth migration from the GSM system to UMTS for multimedia services

Third generation of mobile systems is now entering the operational phase; European Community ACTS (RACE follow-on) programme just aims at finalizing the plenty of solutions resulting from the European Community RACE programme as well as from several other studies and researches. European manufactures, also deeply involved in the ACTS programme, seem to show a preference for solutions which gradually upgrade the present pan-European GSM successful standard. The underlying concept is the one of asmooth migration from the GSM network to the third generation system, in order to reuse, at least in the first phases of the transition, most of the existing technologies and infrastructures already implemented for the GSM network. In this respect, this paper, by referring to radio interface aspects, proposes a two step evolution: in the first step, a Dynamic Channel Allocation (DCA) strategy with distributed control should be implemented for coping with the high variance of traffic entailed by the reduction of cell dimensions; in the second step, a gradual upgrading of the GSM Base Stations should allow a smooth transition towards the third generation Packet Reservation Multiple Access (PRMA) technique and the provision of broadband services. The paper is partly based upon the work performed by the author in the framework of the RACE project Satellite Integration in the Future Mobile Network (SAINT) and of the European Community ACTS Projects MEDIAN. The opinions herewith reported are not necessarily those of the European Community.     

Novel algorithm for time division multiple access in broadband ISDN passive optical networks

For shared access to a broadband communication network using the asynchronous transfer mode (ATM) a passive optical network (PON) has previously been proposed. A novel algorithm to evaluate the time division multiple access (TDMA) protocol which controls the traffic from the various subscribers towards the shared access equipment (upstream direction) is proposed. It uses counters to estimate the moment of a data packet arrival at the subscriber side. By this ‘look-ahead’ technique no extra upstream channels are needed to initiate the polling by the subscriber. The algorithm guarantees fair access for all subscribers and minimizes the necessary overhead. Both the maximum access delay and overhead may be readily calculated, and the obtained results were supported by numerical simulation. Applicability in the standard broadband network environment has been proved by hardware design simulation.     

Frequency-hopping codes for multimedia services in mobiletelecommunications

In this paper, “multilength” frequency-hopping (FH) codes are constructed by modifying the generalized prime codes (GPCs). The new codes have asymptotically optimal cardinality as well as zero autocorrelation sidelobes and cross-correlation functions of no greater than one. They are suitable for the integration of multimedia services (e.g., data, voice, image, and video) with different quality-of-service (QoS) requirements and signaling rates in future telecommunication systems, such as third-generation cellular mobile radio systems, where rate and service quality are dynamically matched to users' needs through the assignment of different-length FH patterns. The use of the new codes in multirate multimedia systems with FH code-division multiple access (FH-CDMA) is illustrated. Providing frequency and time diversities, the applications of the GPCs to an FH time-division multiple-access (FH-TDMA) and FH/time-hopping TDMA (FH/TH-TDMA) system are also discussed. Finally, the use of the codes in optical CDMA systems as multiwavelength optical orthogonal codes is studied     

Traffic studies of a multiplexer in an ATM network and applications to the future broadband ISDN

In the first part of this paper the influence of the arrival process on these three performance parameters is discussed. The values of these three performance parameters depend strongly on the utilization distribution over the input trunks of the multiplexer while the total utilization on the input trunks is fixed. If there is the same utilization on all input trunks, the values of these three performance paramters reach a maximum. This result is also valid for an ATM switching matrix with a separate FIFO buffer at each output trunk. In the second part of this paper some examples are provided of how to apply the results of these studies to the future broadband ISDN which is intended to transmit services with very high bit rates (e.g. 135 Mb/s) as well as services with very low bit rates (e.g. 64 kb/s).     

TOBASCO: an innovative approach for upgrading CATV fiber-coaxnetworks for broadband interactive services

To introduce broadband interactive services in a fiber-coax CATV network with high splitting ratio, a high-density wavelength multiplexing upgrading strategy in combination with conventional TDMA techniques is presented. It features flexible network reconfiguration via wavelength reassignment at the fiber terminating network units, a high interactive services capacity per user, and improved network scalability. On the fiber part of the network the interactive channels are carried in baseband, time-multiplexed (in ATM) in a number of wavelength channels. The article gives an overview of the most distinctive characteristics of TOBASCO. The system architecture as well as the evolutionary upgrade path are presented. The implications of the flexible wavelength allocation scheme on the network topology and, in particular, dynamic assignment strategies are analyzed. Finally, the field trial to be carried out in Gent is discussed     

Optical network for broadband services in the subscriber loop

During the course of the last ten years optical transmission systems have more and more taken over the functions of their copper counterparts in the trunk network. However, replacement of copper-based transmission by optical-fibre-based transmission is only the first step in the utilisation of the large transmission capabilities of optical fibre. Deployment of optical fibres will penetrate further to the local loop to bring broadband and narrowband services directly to the customer. In the RACE 2024 project research is being undertaken towards a cost-effective broadband access facility (BAF) for the small business and residential customer and based on the asynchronous transfer mode (ATM). The authors highlight the characteristics of a suitable passive optical network to be used in the BAF system. Following an overview of the complete BAF system layout, attention is focused on the optical network, topology and realisation aspects