AMUSE: advanced broadband services trials for residential users

AMUSE: Advanced Broadband Services Trials for

Residential Users Marco Di Concetto, Giovanna Pavamni, Corrado Rosa, and Fabio Rossi, ltaltel

Siegfried-Paul, Siemens AG Pierluigi Di Martino, Sirti

Abstract Both the information technology and telecommunications worlds are currently show- ing great expectations for the opportunities offered by the deployment of new and sophisticated services, with increasing levels of interactivity, covering heteroge- neous areas like entertainment, commercial, tourism, information, and education. The AMUSE project in the framework of the ACTS pro ram sponsored by the Euro- pean Union, has answered various questions relatec? to the implementation and

rovisioning of new multimedia services. The means to pursue such objectives has &een the setu and operation of small-scale trials in various European countries, involving rearresidential users. The article first presents the project as a whole. Then the focus i s moved to evaluation of the different technologies experimented with in the field. AMUSE services have been sup lied in the context of trial islands characterized by different access network typoLgies. 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 i s very dif- ficult to highlight particular outcomes from the technical experiments, with so many technologies put in place, some general indications emerging from the de loyment of some of these technologies are supplied. Emphasis is then put on the Pacts 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.

nformation and communication are becoming more and more important in today’s life, not only in business, but also in the consumer arena. The enormous progress in digital technologies for the compression and transport of

high-quality audiovisual content and multimedia at large, and the continuous rise of the Internet are making residential and small office/home office (SoHo) users a more significant part of the Information Society.

Alternative delivery chains, via satellite, cable, terrestrial distribution, telecom networks, and the Internet, are all becoming the components of a unique global scenario where evolutionary paths for convergence have to be clearly understood.

The traditional operators in the respective sectors, telecom and information technology manufacturers, are trying to iden- tify the best strategies to generate business and to better position themselves in the new marketplace, which is characterized

by strong competition, with an increasing number of new emerging actors proposing innovative products and tools.

Moreover, advanced multimedia services are introducing a number of key issues in both the technical and service domains, such as interoperability of systems and platforms, the impact of increasing interactivity, and the need for a careful assessment of user behaviors, preferences, and roles.

In this context, field trial activities can significantly con- tribute to clarifying problems and potentially identifying appropriate solutions. The AMUSE Project has operated, since its start in 1995, with the objective of setting up and run- ning interactive services over broadband asynchronous transfer mode (ATM)-based end-to-end infrastructures and different types of access networks to real residential users. The project, led by Italtel (Italy), has included 23 partners representing all the actors in the multimedia play: manufac-

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turers and integrators, network operators, content providers/brokers and applications developers, research cen- ters, universities, and even a major advertising agency.

From the project, the partners realized that a potential key feature for success in the area of services is the implementation of a well-balanced package of attractive applications. This package encompasses the range of interactive services, including digital broadcasting services (in the switched digital video broadcasting - SDVB - fashion), and is completed with classical Internet services, offered through personal computers or possibly through set-top boxes connected to conventional TV sets, thus realizing a kind of “Internet TV.”

The article first presents the project as a whole, then focus- es on the evaluation of the different technologies experimented with in the field, and concludes with specific aspects of the Italian trial and the relevant outcomes.

The M U S E Project AMUSE is a field-trial-oriented project, furnishing several complex multimedia services to real residential users, making use of a state-of-the-art end-to-end ATM infrastructure from the media server to the set-top boxes or personal computers. AMUSE was carried out in the framework of the Advanced Communications Technologies and Services (ACTS) Pro- gramme funded by the European Union [l].

In the service domain, the project goals included: Demonstrating the provisioning of applications in a number of different areas such as entertainment, commercial, information, and education Thoroughly evaluating user perceptions and acceptance of the demonstrated services Demonstrating the possibility of offering high-quality multimedia services with different levels of interactivity, ranging from no interaction (e.g., broadcast services) to a reasonably high level of interaction (e.g., home shopping) In the delivery platform domain, the project has aimed to

achieve the best overall system solution by addressing the following key issues:

Effective integration in each trial island of a number of different equipment components supplied by different manufacturers Adoption of alternative access network solutions in the different islands, such as asymmetric digital subscriber line (ADSL), hybrid fiber coax (HFC), hybrid fiber radio (HFR) , fiber to the curb (FTT‘C), and ATM passive optical network (PON) Compliance with the emerging standards for interactive and distributive multimedia services Viability of the system choices with respect to the target quality of service, derived from a careful assessment of user requirements AMUSE advanced interactive and distributive

multimedia services were delivered to real residential users in six different trials across Europe: Milan, Italy; Munich, Germany; Basel, Switzerland; Aveiro and Lisbon, Portugal; Reykjavik, Iceland; and Mons, Belgium. Overall, more than 150 users have been involved, with around 8000 hr of trial operation and 800 hr of video material encoded and made available to the users. In order to perform the experiments on a broader user basis, different types of subscribers were selected. The trial run in Munich during 1998 comprised more than 100 active users from different institutions, including a school, a retirement home, a student’s home, occasional users a t a Deutsche Telekom shop, and the Munich Municipal Museum.

The complete list of trials and characteristics is pictured in Fig. 1.

The project consisted of two demonstration phases. The first demonstration phase (May 1996-December 1997) was mainly characterized by a first set of access network technologies and Moving Picture Expert Group v. 1 (MPEG-1) digital content [ 2 ] at up to 2.5Mb/s. The second phase (March 1998-September 1998) introduced new services and new access network technologies, as well as full MPEG-2 digital content [3] at up to 6 Mb/s.

The AMUSE ,Experimental Network Technologies One of the basic choices made by AMUSE (and preserved throughout the project) was the adoption of ATM end to end, from the media server to the terminal equipment, across various types of access networks [4]. In this section a description of the various access technologies is provided, followed by a comparative economic evaluation.

ADS1 Technology A big change is happening in the world of telecommunications. Deregulation and competition are decreasing service prices, while increasing the requirements for network resources. The demand for fast Internet access and bandwidth-consuming interactive multimedia services is dramatically growing, thus straining the telephone infrastructure, the most common means to reach individuals. To address this issue, access providers need to deploy new technologies that can offer significantly higher capacities at reasonable costs. Typically, telecom networks have moved toward broadband transport capabilities in the core, using synchronous digital hierarchy (SDH) or ATM. However, the “last mile” between the local exchange and the end user is prevalently based on already installed copper phone wires, designed for voice communication.

The best evidence for the increasing success of ADSL is the

m Figure 1. The AMUSE triuls and technologies.

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huge number of trials run all over the world using ADSL technologies. The most comprehensive survey is the one supplied by the ADSL Forum [5], which also represents an excellent picture of the overall scenario in which AMUSE is proposing its solution.

ADSL was deployed in three AMUSE islands Basel, Reykjavik) with components from different m turers. Italtel supported the advanced Phase 1 trial in with basic ADSL technology from Orckit, and with over-ADSL adaptation boards and access adaptor tech developed and maintained by Italtel and Orckit in the framework of the project. Siemens supported the Phase 2 trial in Basel with the new XpressLink D systems.

Both the Orckit/Italtel and XpressLink D systems are high- performance multiservice access systems that support both narrowband and broadband services for residential and business customers. They allow for simultaneous transmission of telephone traffic, even integrated services digital network (ISDN), in parallel with ADSL. With current ADSL technology, ATM over ADSL can also be economically provided. ATM enables multiservice signal transmission, future-proof access to broadband networks, guaranteed quality of service (QoS) for all applications, and flexible bit rates to deliver broadband services “on demand.”

The systems provide access up to a range of 5 km over 0.4 mm twisted pair with a bit rate of up to 8 Mb/s downstream and up to 800 kb/s upstream. The systems are rate-adaptive: in the case of particularly critical line conditions, the ADSL modems can select the maximum bit rate possible according to the specified QoS. This is achieved by utilizing a frequency band not used for telephony, extending from 30/120 kHz - for plain old telephone service (POTS)/ISDN basic access - to 1.1 MHz [6]. The two main components of the access system are the access adaptor (often referred to as digital subscriber line access multiplexer, or DSLAM) and the ADSL network termination (NT), that is, the ADSL modem at the user premises.

The access adaptor resides in the local exchange and provides the functions of interfacing and adaptation between the local exchange and each of the subscriber lines. The main functions are the line termination from/to the local exchange, either optical STM-1 at 155 Mb/s or electrical plesiochronous digital hierarchy (PDH) at 34 Mb/s [7], the routing/multiplexing of the ATM streams, operation and maintenance (O&M), and the ADSL line termination functions for the subscriber lines. The access adaptor includes a POTS/ISDN splitter sub- rack, which resides in the local exchange and allows the simultaneous use of both ADSL and POTS/ISDN services.

The ADSL NT is located in the user premises together with the home POTSDSDN splitter. The main functions of the ADSL NT are the termination of the ADSL line, including ADSL O&M functions, the termination of ATM Forum standard 25.6 Mb/s interfaces (ATM25) [SI to/from the terminal equipment, and the ATM transmission convergence sublayer functions.

Available bit rates can be further increased employing very- high-bit-rate digital subscriber line (VDSL) technology [9]. VDSL achieves bit rates of up to 13 Mb/s downstream and upstream for symmetric services and up to 26 Mb/s downstream (and even 51 Mb/s on short distances) and 3.2 Mb/s upstream for asymmetric services, over about 1.5 km. VDSL solutions can be used to address the market for business customers requiring enhanced broadband services.

Finally, ADSL and VDSL systems can be combined with other access technologies, including wireless local loop (digital enhanced cordless telephony, DECT, or code-division multiple access, CDMA), fiber in the loop, and HFC. All these systems can now be handled by a single unified management system.

The AMUSE project trials demonstrated that ATM-over-

ADSL technology is sound and mature, ready to enter the marke lace . It is a very robust and effective technological access solution, offering advantages in terms of ease and speed of installation, excellent performance, and friendly con- figuration, monitoring, and maintenance. ADSL systems are also powerful enough to support a wide range of multimedia services. The downstream bandwidth can support high-quality multimedia, and even the upstream bandwidth is sufficient to support audiohide0 at acceptable quality.

ATM Passive Optical Networks Passive optical network technology can support a wide range of applications, thanks to the amount of bandwidth it offers and the capability to support practically every type of service. Thus, it appears to be the most versatile among the technological solutions now available. ATM PON architecture is typically based on the installation of digital fiber optic networks where an optical line termination (OLT) drives a variable number of network terminations (optical network units, ONUs) to which users are connected. The information trans- mitted by each OLT reaches all the ONUs linked to that OLT thanks to passive optical splitters, thus sharing the incoming optical signal among several outgoing optical fibers.

The strategy for a more rapid deployment of PON-based systems suggests that the product be modular and flexible. It should implement the common functionalities in a single basic module, and have different interface modules to support various configurations, to ensure economy of scale. Based on the location of the fiber section termination (i.e., the location of the ONU), the access network can be classified as:

Fiber to the building (FTT’B), with the ONU installed at the building level, thus serving about 20 households Fiber to the cabinet (FTTCab), with the ONU installed at the cabinet level in the street, thus serving about 360 households In general, the FTTB and FTTCab approaches can be con-

sidered complementary. The network provider can choose between them according to the services planned and the user base characteristics. In the near term, FTTB configurations can be excluded for their higher cost, especially to serve the bulk of the residential market.

The ATM PON solution features unique flexibility of splitting options. The possibility to vary the splitting ratio up to a maximum of 1:32 allows tuning the PON characteristics to the requirements of the offered service, the geographical configu- ration of the served area, and the users’ traffic, thus optimiz- ing cost effectiveness. The ability to cover distances up to 24 km without optical amplifiers also enables the provider to minimize the deployment of active equipment in the access network, with consequent savings in terms of initial investments, infrastructures, and network maintenance. The Italtel ATM PON technology put in place for the AMUSE Milan trial is capable of supporting a net bandwidth of up to 607 Mb/s in the downstream direction (toward the user), flexibly shareable among all offered services, and up to 200 Mb/s in the upstream direction. The difference in bandwidth between the two directions is in line with the asymmetrical characteristics of the residential users’ traffic pattern (e.g., video on demand, Internet browsing services). However, the asymmetry in the ATM PON bandwidth capacity does not hamper the offering of narrowband or symmetrical services to some users’ categories (e.g., videoconference or videotelephony for business customers, bidirectional LAN interconnection services), since the PON bandwidth can be flexibly allocated in both directions, thus serving any type of users.

Plans for extensive PON deployment is underway, starting with the offering of fast Internet access services and switched digital video broadcasting, through to interactive services.

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Other Access Network Technologies in Different AMUSE Trial Islands: Hybrid Fiber Coax and Hybrid fiber Radio

During Phase 1 of the AMUSE project, three trials took place (Munich, Basel, Mons) using a flexible access network architecture on an HFC base. According to the different existing infrastructures in the islands (cables, amplifiers, hubs) the components could be used in every trial with only slight adaptations.

HFC networks are derived from existing cable TV (CaTV) networks. An optical fiber feeder is used to transport interactive signals between the front-end and a fiber hub, where the opto-electronic conversion takes place. Commercial CaTV equipment is used for optical transmitters, receivers, and amplifiers within the fiber hub. The NT can accommodate up to four line cards, each containing the circuitry for transmission over the in-house distribution network and featuring a symmetrical ATM25 interface to the user terminal.

The fiber feeder is based on analogue transmission. Carrier modulation techniques are used to multiplex broadcast and interactive signals. Each STM-1 downstream channel is trans- mitted using a highly efficient modulation technique; a single 64-quadrature amplitude modulated (QAM) carrier, requiring around 30 MHz of bandwidth. Concerning the spectral alloca- tion of interactive channels, a high split architecture is used for the upstream channel; that is, the upstream channel is carried at the higher end of the spectrum. This approach not only avoids the noisy return channel band (5-45 MHz), but also provides much higher capacity for the upstream channel. Using robust QAM, a full STM-1 return channel can be realized, which is shared dynamically by several subscribers through a time-division multiple access (TDMA) protocol.

For the Phase 2 trial in Munich a new broadband radio transmission system was used, with the goal of getting a better technological understanding of how broadband radio can be deployed in a real environment and gaining experience from field scenarios. The necessary hardware components were developed within the framework of the ATM Radio-in-the- Local-Loop (RL/A) project, which is a subproject within the scope of the general program ATM-Based Mobile Broadband Communication for Multimedia (ATMmobil) [lo], supported by the German Federal Ministry of Education, Science, Research and Technology.

Radio in the local loop (RLL) covers the “last mile,” providing wireless broadband access for subscribers to the public network. While RLL is a potentially attractive means of rapid service introduction and alternative suppliers, such a system has to compete with other technologies utilizing an already available infrastructure (e.g., DSL on symmetrical copper pairs). On the other hand, a point-to-multipoint RLL system allows fast deployment (no digging required) and progressive investment according to growing demands. With the exception of the central parts like radio base stations (RBSs) and the required feeder lines to connect them to the public network, additional equipment has to be installed only for those customers who actually subscribe to the service.

The expected result of the RL/A project will be a concept for the economic realization of a wireless broadband access solution, with a total data rate of up to 155 Mb/s in both directions, shared by a number of connected subscribers, that is competitive with wire-based solutions.

The prototype system was designed for the 38 GHz range. For production use, a different frequency range (e.g., 26 GHz) would be recommended since the 38 GHz range in Europe is already very crowded with other services.

Two contradictory requirements govern the design decisions on any broadband RLL system. On one hand, system cost must

H Figure 2. Cost comparison for HFC+CDM, PONFTTC, and ADSL networks.

be low, comparable to the cost of similar wired systems. On the other hand, the properties of the wireless transmission channel require a high degree of transceiver complexity to approxi- mate the high QoS and availability of already existing wired services to which customers are accustomed.

The radius for the radio cell in this field trial is limited to around 300 m, smaller than technically feasible. For a later product, a larger cell radius of up to 2 km is envisaged in order to reach an economic solution that can serve a suitably high number of subscribers per cell. This would result in a suitably high sharing of the common infrastructure costs (e.g., for the fiber feeder and RBS). The problem of multipath propagation in adverse environments has not been adequately addressed to date. Responses of broadband channels, including possible time-variant effects due to moving obstacles within the antenna beam, for different realistic scenarios seem up to now to be largely unknown. Such knowledge is essential for dimensioning a robust, reliable system, especially a point-to- multipoint system with quite different propagation paths within the same system. Adverse multipath condition countermeasures will heavily influence system costs and may even be prohibitive in some cases. In addition, movements of cars make impulse responses time-variant and may mandate adaptive equalizers.

A Comparative Evaluation of Access Network Solutions Multimedia services, generally characterized by high transmission rates and quality levels, and interactivity between customers and service providers, demand the realization of access networks able to guarantee such requirements.

We proposed and tested the following technologies in the AMUSE project: ADSL systems on traditional copper pairs, HFC networks, digital networks based on PON technology and VDSL, and even HFR access networks. The choice of the most suitable solution depends on several factors, such as the type and penetration of services, the quality required for such services, the availability of new equipment, and the presence of infrastructures already realized. Another important factor is the investment for setting up the network (also considering the status of preexisting infrastructures) and its operation and maintenance costs.

Figure 2 shows the costs for the realization of an ADSL network for providing interactive services and of an HFC network with cable data modem (CDM) for providing interactive and CaTV or SDVB services, relative to the cost of a PON system (= 1). These estimates are based on the following assumptions. (Details can be found in [ll]).


An urban area with high user density (10,000 users/km2) is analyzed. For ADSL the complete availability of the copper access network is assumed. Also, for PON m C a b networks the secondary section of the copper network is assumed to preexist. For HFC and PON FTTCab networks, the infrastructure availability for the optical section is assumed equal to 80 percent. The total penetration of both services, interactive and distributive, is set to 12 percent, a value that can be considered a high percentage of penetration for broadband services through ADSL systems. In Fig. 3 the cost per connected customer is drawn, varying the service penetration from 2 to 12 percent.

The costs of the ADSL solution are mostly related to ecluipment and its installation in the central office and

Figure 3. Connected user cost vs. broadband service penetration for ADSL, HFC+CDM, and PON FTTC networks.

c;stomer premises. Using passive NT will reduce these investments costs.

As far as the network infrastructure is concerned, the possible costs of upgrading the copper network to the level necessary for the optimized operation of ADSL systems must be taken into account. Among these are the measure- ment costs for the selection of the pairs that have the best physical characteristics, and the costs of setting up an in- house network.

Among the architectures for providing the interactive and CaTV/SDVB services, HFC+ CDM networks have the highest cost, largely due to the realization of the entire coaxial network. Regarding PON FITC, it can be noticed that the installation of ONUS at the cabinet level involves the reuse of the secondary section of the copper network, and therefore a reduction of costs. However, the interactive service penetration can reach a limit that can be exceeded only by moving the ONUS closer to users.

Figure 3 shows that the cost per connected customer, varying the penetration of the services, goes down remarkably for HFC+CDM and PON FTTC architectures due to the presence of equipment and infrastructures shared by all the customers. The figure also shows the high scalability of the ADSL solution, whose cost per connected customer remains almost constant.

In Fig. 4 the costs necessary for the realization of a complete new network for providing all the following types of services, from the traditional narrowband services to the new broadband services, is highlighted:

POTS/ISDN with 100 percent penetration Broadband services (CaTV/SDVB and interactive services) with 35 percent penetration Symmetric data 2 Mb/s with 2 percent penetration In an area with high user density (10,000 users/km*), with-

out network infrastructures, the first installation cost of a full- service HFC network, comprehensive of CDM and cable telephony systems, and of a network PON FTTB is evaluated. The broadband service penetration for these architectures is set to a value higher than in the previous case, varying from 12 to 35 percent in Fig. 5 .

We observe that the relative investments for the two network architectures do not differ substantially. The PON FTTB network has a slightly higher cost, in part due to its relative technological infancy. On the other hand, it has no limitations on the available bandwidth, especially in the upstream direction, and allows the management to be simpli- fied, thanks to the homogeneity of the equipment. As the penetration of the broadband service increases, the investment per connected customer decreases for both networks due to the costs being shared among an increasing number of customers. However, because the shared cost is higher for the PON FTTB network [ 121, the higher the percentage of

Full-service HFC Full-sewice PON FlTB

W Figure 4. Cost comparison for full-service HFC and PON FTTB networks.

broadband service penetration, the lower the difference of cost between the architectures.

The AMUSE Milan Trial Experience During the AMUSE project framework, three field trials took place in Milan, Italy. The first one started in September 1996, experimenting with a first generation of ADSL access systems. This was upgraded during an Advanced Phase 1 trial with the new systems jointly developed by Italtel and Orckit to support ATM over ADSL with significantly increased bandwidth. The Phase 2 trial in 1998 was focused on the deployment of a completely new software platform based on the Oracle OVS3.0 video streaming software and Network Computing Architecture, allowing Java-based authoring and dynamic Hypertext Markup Language (HTML) support. The Phase 2 trial also involved the ATM PON technology.

This section will first describe the AMUSE Milan infrastructure and the offered services. Technical aspects of multimedia service support then follows. We conclude with a summary of the main service and technical outcomes of the Milan trials associated with the ADSL deployment.

The AMUSE Milan Infrastructure The AMUSE ADSL Milan trial platform was distributed over five main sites, as depicted in Fig. 6:

The user area in downtown Milan, with users equipped with set-top boxes and PCs, connected with ATM25 interfaces to the ADSL modem toward the ATM/ADSL access network over conventional copper pairs The local node where the ADSL access adaptors perform multiplexing/demultiplexing functions from/to the different ADSL modems on one side and the 34 Mb/s PDH on the network side (in order to optimize the usage of the PDH links and perform remote control of the local office equipment, an ATM service multiplexer has also been installed) The ATM International Gateway, giving access to the Euro-

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pean ATM for interconnection experiments with other AMUSE trial islands and bridging the residential users with the core of the platform, as well as providing connection to the Internet gateway and server The server area at the Italtel premises in Settimo Milanese with the interactive media server, an Italtel ATM node, the SDVB server, and the monitoring and remote control systems [13] The content provisioning area in the Videotime premises in Cologno Monzese, where most of the contents have been made available and encoded in MPEG format

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - - - _ _ _ .-

Figure 5. Connected user cost vs. broadband service penetration for The AMUSE Services in the Milan Trial The provision of interactive services depends critically on the performance of the overall system, demanding strong interdependencies and feedback between the different key players: the end user at home; the service provider (supplying services and relevant billing); the content provider (supplying content, as well as categorizing and indexing it); and the network provider. However, the success of the new services remains largely based on users’ acceptance and satisfaction. Thus, service requirements from the users’ point of view are a crucial issue [14]. For this reason, a significant amount of effort was invested in preparing the applications and acquiring content.

The reference criteria used in building the “package of applications” offered to users are:

Refer as much as possible to a complete offer, including interactive services, distributive services, and access to the Internet.

* Cover a wide range of interactivity levels. Include applications that can ensure frequent access (on a daily basis in principle). Integrated services support (as shown in Fig. 7) appears as

another mandatory requirement of the next generation of set-

fill-se,.,,ice HFc and ~ o N F ~ B nenuorh.

top boxes. The customer equipment will have to be able to access all the different worlds of Internet, broadcast TV, and interactive multimedia services.

First, the user is allowed to enter the “AMUSE world” through the Common Welcome Shell, the application in charge of providing the initial environment and allowing its customiza- tion according to the user’s needs or preferences. The Common Welcome Shell can be downloaded to the set-top box as a start- up menu and enables the user to perform the initial choice of functions or applications. Other menus are later sent as a result of user commandslchoices. A number of applications can then be accessed, such as Movie Catalogue, News on Demand, Infomercial on demand, TV programs on demand, Broadcast- ing TV, and Tourist Information & Support. Additionally, a Music Compilation application is offered, exploring the leading edge of technology applied to audio compression and distribution over broadband platforms. It allows browsing, searching,

H Figure 6. The AMUSE Milan trial infrastructure.

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a b

Figure 7 . The AMUSE integrated services offering.

retrieving, selecting, and playback of high-quality audio com- pressed files in a library, as well as creating, editing, storing, and managing personal compilations. Tele-shopping allows the user to purchase products by browsing through virtual multimedia stores. Movies and TV Programs Poll, which enables users to post their opinions on programs from a catalog, and Direct Democracy, where users are asked their opinions about various social issues, complete the AMUSE service offering.

Technical Aspects of Multimedia Services Support The AMUSE services have been implemented by using three alternative software platforms, thus allowing the building up of different user interfaces characterized by different levels of complexity and attractiveness.

The applications initially offered were first developed using a proprietary authoring tool and later the commercial Oracle Media Object platform. They typically consisted of stacks or sets of stacks, each composed of cards, containing their own graphical layer, as well as various objects linked and con- trolled by a rich, high-level scripting language.

Our experience indicates that multimedia applications should be designed to minimize processing requirements, while preserving the appeal and ease of use of the interface. On the application developer’s side, design flexibility is important to make it easy to modify the appearance and supported capabilities of the interfaces.

A good authoring tool should have the following features. It should enable the creation and deployment of highly interactive multimedia applications in a fast and robust way. It should be open and upgradable to easily integrate new objects. It should offer a friendly graphical user interface to the application developer and have an easily interpretable scripting language.

Another crucial aspect is the ease and effectiveness of interaction with the program database. In this sense, combined access to the database for rapid and easy update of content descriptions and search keys has been fundamental for an effective service deployment. As an example, the refresh rate of contents for a number of services (News on Demand above all) represents a challenging issue in terms of service management. The possibility to efficiently automate database updates and consequent user interface updates while uploading encoded contents thus represents a big advantage. The latest platform used to develop AMUSE applications is Oracle NCA (Network Computer Architecture, now E A , Internet Computing Archi- tecture [15]) based on HTML-Java [16] pages created dynamically on a Web application server and delivered to the client

(set-top box). The platform is able to interact with a database to keep data and information, and organize them into HTML pages to be displayed on the TV screen, and to deliver movies to the end user by using the Oracle Video Server platform.

NCA has the advantage of high portability, being totally built on standard components: a Common Object Request Broker Architecture (CORBA) 1.2 ORB [17] for communication between client and server and inside the application server, HTTP for connection to client browsers, and Java, ODBC, and JDBC (Java Database Connection) [18] with PUSQL for access to the database. With NCA, porting was easy and fast, being based on normal HTML page processing. Applications run fast, even when accessing the database for large amounts of data. Fur- thermore, with NCA the set-top box need not interpret any object, since the HTML pages are created inside the server and then sent to the STB. This results in a very short processing time.

On the other hand, the Java Virtual Machine (JVM) is highly demanding in memory and processing power. Thus, no application implemented makes use of Java applets; only stati- cally or dynamically built HTML pages are used. The JVM is loaded anyway during the boot phase to improve access speed to possible Internet sites that will be surfed by the user using the Internet TV application.

Service-Related Experiment Results User acceptance of the offered services was evaluated through questionnaires and automatic monitoring tools (related to the logging facilities of the media server platform). In terms of service acceptance and perceived quality, the following indications have emerged from the Milan trial and have been generally confirmed by almost all the AMUSE trials [19]:

Users have shown high interest in being involved in the trial and have also been attracted by the wide package of services, including fast access to the Internet. Video on demand is considered interesting (in particular, TV programs and music on demand); but content always has to be very appealing and up to date. The direct involvement of content providers in the trial is of crucial importance; from this viewpoint the Milan trial has been in a very good position, with participation in the con- sortium of Videotime, a major Italian content producer. Users are in principle interested in the Infomercial service. However, mixed user feelings have been detected as far as tele-shopping is concerned, largely depending on the type of goods sold (more difficulty with expensive ones, e.g., cars, computers, or houses); electronic commerce has raised


great interest among both providers and users. It is widely understood as one of the most promising applications for both the Internet and multimedia interactive worlds. A new way of providing advertising in the interactive multimedia world should be identified; neither the TV spots nor Internet Web pages seem to represent an optimized approach to better exploit the direct marketing potential of the new media. News on Demand suffered from the fact that the offering was limited, and up-to-date news reports are frequently available elsewhere; a more sophisticated service giving the user the possibility to build up a customized news report choosing news out of a large catalog can probably seize user interest. Friendliness and attractiveness of the user interfaces is a very important issue, and in this sense the use of Web- based authoring tools brought far better results. As far as usability is concerned, the general comment of users was that the system is easy to learn and to use; the only concern was related to the multiplicity of remote con- trols users have to manage. The perceived quality of video and delays/latency was evaluated as acceptable; the perceived quality of the audio was evaluated as good. Provisioning of MPEG-2 encoded contents allowed enhanc- ing the picture quality of the contents delivered and enhanc- ing the overall service perceived by the users. This avoids the “flickering” effect due to the interlaced images of TV programs on the MPEG-1 progressive frames scanning, and introduces robustness at the transport layer on the content streaming flows to reduce loss of data. From the user’s viewpoint, higher quality was recognized, particularly for sports programs with fast-moving images and scene changes. As far as fast access to Internet service is concerned, the

following indications have emerged: Internet on top of an ATM backbone is feasible and effective, and more indications have emerged with increased bandwidth per user thanks to the new ADSL systems. How- ever, access to the Internet is fast as long as users can access Web servers connected to a broadband Internet platform, while access to the worldwide Internet still suffers dramatically from such bottlenecks as trunk and server capacities. Interviews showed that the users regard Internet access as a fascinating medium providing a worldwide platform for information retrieval; however, within future field trials more concrete applications like home shopping, home banking, or electronic commerce should be experimented with on the Internet itself. Acceptance of Web browsing with the set-top box and TV set was surprisingly high among the families selected during Phase 2. This is mainly due to the higher efficiency and functionalities supported by the latest browser version; however, the inability to save files locally raised some con- cerns. Skilled users still prefer the PC to the TV set for browsing and displaying Web contents.

Technical Experiment Results The technical experiments performed have been aimed at char- acterizing the specific aspects of the Milan trial (i.e., those related to the use of the ADSL asymmetric user channel).

During the installation phase, all the individual elements have been characterized with respect to bit error rate by monitoring the bit or pattern error at the ATM layer. No errors were recorded; thus, as far as the ATM layer is concerned, the chain may be referred to as “zero-loss delivery chain.” Mea- suring cell transfer delay (CTD) and cell interarrival time (CIT), the recorded values highlight how ADSL integration

periods affect CTD values. This is specific to the ADSL access network the delays are due to the user signal elaboration pro- cess that has to integrate the signal on a time period long enough to clean it from all the impulsive noise.

As a more general characterization, the typical time behavior of different situations (navigation, VCR emulation, etc.) during the user activity lifetime was measured. No differences were detected between a laboratory experiment and the real network environment. Basically, this is due to the fact that the delay of the ADSL integration periods dominates the latency on the transmission path across the in-field networking platform. The only larger delay is introduced on the complete application download procedure, the duration of which is approximately twice as long. Improvements could be still obtained by working on the boot protocol characteristics (nfsboot), but this was out- side the scope of these preliminary experiments.

From the technical viewpoint, no significant differences have been discovered comparing the end-to-end PON platform with the ADSL chain in terms of either service quality perception or measured parameters. Obviously, VDSL access allows more efficient use of the upstream channel, but this may really be appreciated only when more than one user client is connected to the same NT, because the 768 kb/s upstream channel of the ADSL NT may become a bottleneck when, for example, both a set-top box and a PC are connected to the same user access.

lessons Learned Overall, a number of major lessons have been learned from the trials, and a number of key factors for success of interactive multimedia have been identified.

It is important to run small-scale trials before investing huge amounts of money in larger market trials. In a scenario ruled by competition, exploit the benefits of synergies between all the actors involved in the delivery chain of multimedia services. A successful service offering is based on a complete and integrated suite of interactive, distributive, and Internet access services (also in Internet TV fashion). Without interesting and stimulating content, interactive multimedia will not succeed in the long term. Carefully analyze the customer role and service acceptance to better tailor service implementation and provisioning to final user needs; design user interfaces which are friendly, to widen service accessibility, and engaging, to make service usage attractive. Choose an open, flexible, universal service platform according to the emerging Web-based paradigm to ease service management and portability over different client-server platforms. The platform will have to include state-of-the-art MPEG streaming functionalities over broadband ATM con- nections to ensure that TV-quality real-time full-screen video can be delivered on demand to any final user. The current marketplace for interactive multimedia products is being held back, in part, by the lack of standards, which in turn engenders multiple solutions which vary in their facilities, costs, and cost effectiveness. To overcome the problems of incompatibility, a more standard approach is needed at all levels. Focus on low-cost solutions, with particular attention to consumer equipment. Finally, in terms of access technologies, many solutions have

been proposed and tested within AMUSE: ADSL systems on copper pairs, HFC networks, digital networks based on PON technology and VDSL, and even a broadband radio access technology. The evaluation of the most suitable solution


depends on several factors. Certainly, fiber in the last mile to the buildings is at the moment too expensive and disruptive to

upgrades are necessary. Thus, ADSL technology an ants [20] appear as the most appropriate strategy to s high bandwidth in the last mile, even for residential users.

Conclusions The world of multimedia, once the domain of information technology and typically restricted to expensive high-performance computing platforms, has seized increasing interest in the last decade in the fields of telecommunications and broadcasting.

The recent breakthroughs in digital transmission over different physical media (coax, copper pair, fiber, and even wireless) and in video compression are making the offering of advanced multimedia services to residential users technically feasible and economically viable. But the identification of applications capable of effectively stimulating the demand for broadband services by the "consumer" market (where con- sumers are residential, SoHo, and community network users) is still an open issue.

Trials around the world have started focusing on video on demand services, mainly concentrating on movies on demand, but this monothematic offering is probably too restrictive. The competition from traditional broadcasting services, initially analog and then digital, was and still is strong, and the cost of accessing them reasonably cheap. Also, the competition of low-cost videotape rental offerings has hampered the take-off of movies on demand. Strategies thus changed toward wider service offerings in more or less integrated packages.

Cost is a crucial issue to break into the enormous market of residential users. In addition, while it is vital to consider the general trends, the different technical and cultural differences in the various countries must be kept in mind.

In order to better understand the new customer role and behavior in the face of new multimedia service packages, while improving the knowledge of likely strategies for the take-up of such services over different delivery platforms, the AMUSE project started building up small-scale trials which helped gain experience in a number of key areas (integration, setup, management, operation, application, content provisioning, etc.). Such trials and the relevant results have proven particularly useful to drive the new strategies for the provisioning of advanced multimedia services and to pave the way toward a more rapid and effective deployment of broadband technologies, for which multimedia is the most significant leverage.

References [ 11 ACTS Call Doc. Ref: DGXIII-B - RA946043, Aug. 17, 1994. [2] ISO/IEC 1 1 172, "Infanakm technology - Coding of w i n pictures and asso-

ciated audio for digital storcrge media at up to about 1 3 N\bgs," 1 ?93/1995. [3] ISO/IEC 1381 8, "Information technology - Generic coding of moving pic-

tures and associated audio information," 1995. [4] ITU-T Rec. G.902, "Fromework recommendation on functional access net-

works (AN) - Architecture and functions, access types, management and service node aspects," Nov. 1995.

[5] "ADSL Trials Worldwide," "ADS1 Service Deployments," ADSL Forum Sur- veys, Jan. 7, 1999.

[6] AMUSE Del. E03, "Upgraded ADSL for Phase 1 demonstration," Apr. 1997. [7] ETSl Tech. Spec. ETS 300 299, "Broadband Integrated Services Digital Net-

work (B-ISDN); Cell based user network occess; Physical layer interfaces for B-ISDN applications."

[8] ATM Forum, "ATM TC and PMD Layers for the SB Reference point ot 25.6 Mb/s over Twisted Cable."

191 ETSl DTR/TM-06003, Transmission and Multiplexing (TM); Very High Speed Subscriber lines (VDSL) functional requirements."

[lo] AMUSE Del. D16bis, "Phase 2 platform integration report," rei. 2, Dec. 1997.

[ l 11 "The new braadbond network solutions," FITCE Cong. '97, Thessoloniki, Greece, Sept. 22-27, 1997.

[ 121 AMUSE DeliveraF D21, "Final architecture description, exploitation report and business plan, Sept. 1998.

11 31 A. Daniele et al., "Distributed and Interactive Multimedia Services: An Inte- grated Approach," Proc. ISS '97, Toronto, Canada, Sept. 21-26, 1997.

[14] N. Negroponte, Being Diftal, Knopf, 1995 r, June 1997. [15] "Network Com uting Arc itectureTM," Oracl

[16] D. Kramer ( w i t contributions by B. Joy and ),?e Java Platform White Pa r May 1996.

[17] S. Vinosc :'CORBA: Integrating Diverse Applications Within Distributed Het- erogeneous Environments," /€€€ Commun. Mag., vol. 14, no. 2, Feb. 1997.

[ 181 !-lamilton, Cattell, and Fisher, "JDBC Datobase Access With Java - A Tuto- rial and Annotad Reference," JavaSoft Press, Addison-Wesle Jul 1997

[ 191 AMUSE Deliverable D20, "Final report on the service re1ate;rbndYtechnicaI outcomes of the Phase 2 demonstrations," Oct. 1998.

[20] ANSI Std. T1.413, "Network and Customer Installation Interfaces - Asym- metrical Digital Subscriber Line (ADSL) Metallic Interface," Mar. 1995.

Biographies MARCO DI CONCETTO ([email protected]) received a degree in electrical engineerin in 1987 at the University of Bologna, Italy. In 1988 he joined ITALTEL R&D. Initio$ he worked on N-ISDN and IN services. Subsequently, he was involved in the design and specification of protocols and services far B ISDN, participating in various national and international projects and standardization activities. He was responsible far the ltaltel participation in Sub-project 4 of PFT-CNR, taking care of the develo ment of an ATM signalling protocol tester. He is presently working on broadban8 services specifications and protocols, with rticular attention to interactive audiovisual and multimedia services. Since 1996 e has been project manager of the ACTS project AMUSE, one of the major EC funded projech in the multimedia domain in the Fourth Framework Program. He has also been author of a number of papers addressing broadbond networks and multimedia supporting techno1 Currently, he is also responsible far Multimedia Projects within Italtel's Shakgic?!;: ning and Innovation/Advanced Research Deparhnent.

GWANNA PAVARANI ([email protected]) received her degree in electronic engineering at Politecnico di Milano, in 1995. After receiving a Master's dTree at CEFRIEL (Center far Research and Education in Informotion Technology, Mi an), she joined ltaltel Central R&D Labs where she is currently working as a network and software en ineer, with particular attention to the design of orchitec tures for the support of a%anced multimedia services over broadbond platforms.

CORRAD~ ROSA ([email protected]) graduated in electrical engineering in 1992. He started working on image processing at the beginning at the University of Genoa and then at CEFRIEL in Milan. In 1994 he joined ITALTEL R&D. Since then, he has been responsible for interactive agplications development for the AMUSE project. Currently, he i s olso responsi e for multimedia services and applications within Italtel's Strategic Planning and Innovation / Advanced Research Department. He is also involved in the desi n and specification of protocols and services for 8-ISDN. He has been the auxor of a number of papers addressing broadband networks and multimedia supporting technologies.

FABIO ROSS ([email protected]) received a de ree in electronic engineering at Politecnico di Milano in 1987. Then, he joined ltalte?Centrol R&D Laboratories, where he has participated in several activities related to the design and implementation of broadband ATM swikhing architeavres. He also participated in o number of research projects on multimedia services, and advanced intelligent and mobile networks, with responsibility far s stem integration ond design. He is currently managing the ltaltel Advanced Researcl Laboratories broadband platforms and has been the manager of triols integration and planning within the AMUSE ProLFt. He also co-author of a patented sdution for multipoint call control in ATM switc in9 equipment.

SIEGFRIED PAUL (Siegfried.PaulQicn.siemens.de) got his diploma in mathematics in Kiel, Germany, in 1983. He then joined the Corporate Research and Develo ment Department of the Siemens Company in Munich, where he worked on so[: ware development, especially object orientation. Since 1993 he has been with the Research Deportment of the Public Communication Networks Group partici- ating in the development of ATM switchin systems. Within the AMUSE project

r e organized the second field trial in Munick

PIERLUIGI DI MARTINO ([email protected]) received a degree in electronic engineering at Politecnico di Torino, Italy, in1994. In 1995 he joined Sirti, Research and Development Division, as o network s stem engineer. He is involved in specifico- tion of principles and methodol ies L r access network planning, by means of a techno-economic assessment ?network alternatives for the provision of new telecommunication services. His activities concern the analysis of different occess network architectures, with emphasis on CO per network architectures, hybrid fiber and coax networks (HFC), and hybrid fi&er and twisted pair networks using PON/VDSL technology. The study aims at analyzing the architectures in terms of both residential and small business customer requirements, strategic goals of a network o erator, and foreseen service penetrations. He takes part in writing technical Lcuments and publishing papers obout issues concerning various network solutions and results of the techno-economic evaluations.


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AMUSE: advanced broadband services trials for residential users