Broadcast and multicast - a vision on their role in future broadband access networks

L.Henden (ed.), N. Chuberre, L. Combelles, G. Corazza, S. Danton, T. Flo, D. Grace, T. Kourtis, H. Le-Bihan, H. Linder, A. Nordbotten, E. Pallis,

T. Tjelta, A. Vanelli

5 January 2005

AbstractBroadcast and multicast offer a significant improvement of spectrum utilisation, and becomes particularly important where information channels are shared among several users. Furthermore, the evolving electronic based society will more and more take advanced information technology into use involving multicast sessions of one-to-many, many-to-many, and many-to one. This document provides a vision about the role of broadcast and multicast in broadband access networks including the main advantages, a roadmap, and future research items. The latter form the basis for coordination and collaboration amongst European Union funded projects within this area.

KeywordsBroadband access, multicast, broadcast, spectrum efficiency, information society

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Content PageBroadcast and multicast - a vision on their role in future broadband access networks..............1Executive summary.....................................................................................................................31. Introduction (1 page)..........................................................................................................42. Broadcast and multicast absolutely necessary in broadband access networks (5 pages). . .5

2.1 Rationale.....................................................................................................................52.2 Multicast applications.................................................................................................62.3 Traffic development trends.........................................................................................72.4 Service development trends........................................................................................82.5 Network capacity and cost reductions......................................................................11

3. Technical solutions trends (5 pages).................................................................................123.1 Solutions for mobile access......................................................................................12

3.1.1 3G Cellular MBMS: Multimedia Broadcast Multicast Service........................123.1.2 Terrestrial broadcasting infrastructure..............................................................13

3.1.2.1 T-DMB: Terrestrial Digital Multimedia Broadcasting.................................133.1.2.2 DVB-T: Terrestrial Digital Video Broadcast................................................133.1.2.3 DVB-H: Digital Video Broadcast for Handheld terminals...........................13

3.1.3 Satellite infrastructure.......................................................................................143.1.3.1 SDMB in Asia...............................................................................................143.1.3.2 SDMB in Europe...........................................................................................14

3.2 Solutions for fixed broadband access.......................................................................153.2.1 DVB-IPI............................................................................................................153.2.2 GSB...................................................................................................................153.2.3 High Altitude Platforms as a new means of wireless broadcast/multicast delivery 15

3.3 Solutions for fixed and nomadic/mobile broadband access......................................164. Topics requiring new research results...............................................................................18

4.1 Multicast Routing in Broadband Networks..............................................................194.2 Quality of Service.....................................................................................................194.3 Reliable multicast transmission and scalability........................................................204.4 Secure multicast and digital rights management......................................................214.5 Future on-demand services.......................................................................................214.6 Local storage and local caching................................................................................224.7 Fair Share of Revenue using multicast.....................................................................224.8 Spectrum efficiency including RRM........................................................................234.9 End-user requirements..............................................................................................254.10 Digital switchover.....................................................................................................25

5. Roadmap 10 years ahead (3 pages)...................................................................................275.1 Migration from connection oriented (ATM) to connection less networks...............275.2 Introduction of IPv6..................................................................................................275.3 Evolution of Multicast and Broadcast in Broadband Networks...............................275.4 Triple Play and beyond.............................................................................................28

6. Inputs for standardisation and regulation (2 pages)..........................................................306.1 Technology independent multicast...........................................................................306.2 International standard bodies....................................................................................306.3 Spectrum issues and related bodies...........................................................................31

7. Conclusions (1 page).........................................................................................................32References.................................................................................................................................33Annex 1 Projects provided contributions and comments.........................................................34

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Executive summary

Broadcast and multicast in broadband access networks play an important role in content delivery by increasing the capacity utilising spectrum efficient techniques. In addition it facilitates increased availability and usage of electronic based services and business by reaching the majority of the citizens. The vision of e-Europe is indeed to get people actively participating as well as to increase productivity, create jobs, and modernise public sectors. Electronic services involving many-to-many communication are necessary. In this vision, broadcasting and multicasting schemes are expected to play a significant role.

It is broadband networks that bring the most promising future perspective. Broadband enables the information society and is seen as necessary for the future, for Europe as well as worldwide. Multicast comprising one-to-many, many-to-one, and many-to-many communication models is exactly what is needed for a modernised competitive society. Broadcast is a very efficient method to reach everyone with downlink broadband contents. Although interactive digital broadcast is a first step, the real challenge is a full and real time interactivity, which is possible only by using the uplink. Therefore both multicast and interactive broadcast form an important element of the broadband information society.

The Internet traffic patterns are currently changing from asymmetric web browsing to peer-to-peer applications sharing broadband type content such as music and videos. As a result the traffic in the uplink is increasing quickly and will approach the downlink traffic.

The terminals are not as they were. Computers are getting smaller and smaller to become handheld devices with huge storage and connected to the broadband network. People will be connected to the broadband network both in fixed and mobile modes.

There are many issues that still need development: in particular, security and quality of service issues. The services have to be safe to use, and bandwidth provided with some sort of guarantees for real time applications.

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1. Introduction

The traditional way of data communication has up to now, mainly been from one host to another (unicast). Historically broadcast networks have provided virtually everyone with a broadband one-way channel, offered by satellite, terrestrial broadcast systems, and cable networks. On the contrary, unicast-based delivery mechanisms dominate for Internet video and audio services. As a consequence, many simultaneous connections and a large amount of bandwidth and server processing power are required to serve a user community of a sufficient size. As the number of users connected via broadband techniques increases, the more the demand for audio and video content is expected to increase. Thus bandwidth and server requirements will increase very fast within the next years. The current solution for this problem is to increase the capacity of both the backbone and the server at the same speed, as well as the capacity of the access network, so that the end-user terminals may receive higher bit rates.

The development today, goes mainly in two directions. The traditional broadcast distributor wants to offer a full set of services including interactivity as well as both audio and video based IP telephony. The new broadband network operators will in addition to data include the traditional broadcast type of services, as required by their users and service providers, and even extend TV provision to a more combined provision of video services. Using the traditional broadcasting and unicast-based delivery mechanism will represent a waste of capacity and become expensive. This is where IP multicast represents an interesting solution.

The motivation for this document is to highlight the significance of broadcast and multicast in broadband wireless and wireline access networks and to describe the challenges such services face. There will be several important drivers to introduce broadcast/multicast schemes, both on the technology side and on the service and application side. Three of the drivers are of special interest, saving of bandwidth, economy and the introduction of e-based services.

In addition the vision document will serve as an input for an active collaboration between projects addressing broadcast and multicast issues. Much more can be achieved if research activities are coordinated. In disseminating joint activities makes it considerable easier to reach a larger audience with better results. The participating projects results can also expect to offer increased influence on international standards due to the massive support from many projects, businesses and organisations.

This document is organised as follows. Chapter 2 discuss some of the reasons why broadcast and multicast is absolutely necessary in broadband access networks, and the driving forces behind. In Chapter 3 the technical solution trends both for mobile, nomadic and fixed access are presented. Chapter 4 discusses the topics requiring new research. Chapter 5 presents the roadmapping aspect over the next 10 years, and finally in Chapter 6 potential inputs for international standardisation bodies are presented.

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2. Broadcast and multicast absolutely necessary in broadband access networks (5 pages)

2.1 RationaleThe number of broadband users has been growing rapidly during the last years. It is not only the number of users that increases but also the average data volume per user. A consequence of the increased number of users connected via broadband techniques is that the demand for audio and video content is also increasing. This is leading to many new bandwidth-requiring applications. Thus bandwidth and server requirements will increase fast. The current solution for this problem is to increase the capacity of both the backbone and the server at the same speed. This is a cost-intensive concealment of the real problem, but not a solution.Other changes are how the Internet is used. Up to now it has mainly been used for data traffic, where the communication is going from one host to another (unicast). The typical use of Internet has been for downloading of information. Today there is an increased interest for entertainment services, including audio and video. The development trend moves towards an Internet delivering all kind of services, telephony (VoIP), multimedia, broadcasting and data etc. This results in a change in the communication method, going from one-to-one (O2O) to one-to-many (O2M), many-to-many (M2M) and many-to-one (M2O), interaction methods benefiting from the multicast technique.

Broadcasting technology and services have been around almost as long as the radio communication itself, and have for more than half a century, been a broadband channel to the user. The development now is towards fully digital broadcast networks with return channels enabling out-reaching two-way communication in addition to traditional broadcast services. The change now from terrestrial analogue television to digital technology will certainly become very important and make the convergence between broadcasting and communication happen. As a broadcasting service the digital terrestrial television (DTT) can also be regarded as a mobile services and a multimedia fully converged platform becomes a reality. The strength is the coverage making it possible to connect rural areas with a low cost technology. The weakness is currently the return channel where the challenge is a true broadband uplink. The transition from analogue to digital broadcasting is called the Digital Switchover (DSO). DSO was considered by the Sevilla European Council, 21-22 June 2002, as a key and critical element towards the establishment and successful deployment of Information Society (IS) all over Europe aiming at secure the applications and content, based on a widely available broadband infrastructure.

In the Internet multicast is an important method for broadband delivery to many, and, clearly, for bandwidth limited networks such techniques are absolutely necessary. The trend towards a society increasingly using Internet for more and more advanced services not only leads to broadband capabilities in the delivery but a two-way access network efficiently serving applications involving many at the same time.

Economy is another issue that is important when multicast is introduced, both for the content provider and the network operator. Multicast services have up to now been significantly more expensive than unicast services. The cost is related to network deployment, installation of customer premises equipment, and management and maintenance. As the number of users increases it is expected that the cost per user will be less for multicast than for unicast. For

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unicast each new receiver adds a constant cost, while for multicast the initial costs are higher but the cost of adding new receivers decreases proportional with increasing number of receivers. However the use of multicast only make sense when the bandwidth savings are larger than the deployment and management cost, and for large groups multicast should be a profitable and useful service.

Broadcast and multicast over wireless and wireline broadband access networks is an important and challenging goal, but there are several issues that require further research before new group applications can be deployed on a large scale. IP Multicast is an efficient technology for supporting group communication, as it allows transmission and routing of packets to multiple destinations using minimal network resources.

It is apparent that people are becoming increasingly connected by broadband technology. On the other hand, it is also apparent that certain groups are growing far more rapidly, particularly with respect to Internet connectivity. This pattern shows that some groups are lagging behind. This is the so-called digital divide. The digital divide and its consequences has become as a concern for society and its inhabitants. It represents a threat to the development of an information society serving everybody. Concerns expressed in media discussions have however created a common awareness among people about this. And it has thus become a political goal to offer broadband access to everybody. It is expected that the community type services or e-Europe type services will develop when the number of users reaches about 50-60% of the population. E-Europe type services refer to services such as e-government, e-health and e-learning. Typically for them are that a huge amount of information should be delivered to many receivers. These are all bandwidth requiring services which will take advantage of multicast.

The main driving forces for broadcast and multicast are: Effective utilisation of bandwidth Economy Participation in the modern e-society

In addition there will be several other driving forces both on the technology and the application side that will push the development of towards more use of IP multicast.

2.2 Multicast applicationsMulticast-based applications and services will play an important role in the future of the Internet as the understanding increases and thus promote the use. There are several types of multicast applications, but in general they can be divided into three categories [1]:

One-to-many: A single host sending to two or more receivers. Many-to-many: Any number of host sending/receiving to/from the same multicast

address. Many-to-one: Any number of receivers sending back to a (source) sender via

multicast.Several requirements have to be considered, and they vary for the different applications.

One-to-many

One-to-many applications with a single sender and many simultaneous receivers are probably the most used and the easiest when it comes to bandwidth and delay requirements. The application that is most often connected with multicast is broadcast based multimedia applications, such as television and radio. Some applications in the one-to-many category are:

Scheduled events: video, audio, meetings etc.

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Push technologies, for distribution of news, stock quotes or other real-time data. File distribution and caching

It is important that services such as TV-distribution and video have a schedule. Video-on demand is often mentioned in connection with multicast, but the same video is seldom chosen at exactly the same time and is therefore not a service suitable for multicast.

Many-to-many

In many-to-many applications there are a number of hosts sending to/receiving from the same multicast address. Each host running this application may receive data from multiple senders and at the same time they also send data to all of them. The result is that it is within this category the most bandwidth requiring applications are found. Some of them are:

Multimedia conferencing, were multiple data-streams of video, audio and whiteboard are going to be coordinated

Collaborative applications, e.g. co-ordinations of interactions between members of a group

Multi-player games

Many-to-one

Many-to-one applications have many senders and one (or a few) receiver(s). The application could be one-way or used as a two-way request/response protocol. There is no standard available for many-to-one applications yet. An example of this application could be auctions, where bids from many potential buyers are sent to a multicast address (the auctioneer).

Many different applications have been developed for the use of IP Multicasting. The applications can often be categorized according to weather they are real-time or non-real-time and if they are multimedia or single media data (data only).

2.3 Traffic development trendsThe demand for highly asymmetric services, with more downlink capacity than uplink capacity has been dominant up to recently. It is however expected that the users wish to use more and more uplink capacity as an increasing number of users have access to broadband services. Today, only a fraction of the population in Europe have broadband access, and it is believed that there need to be a critical mass of users before these users require more uplink capacity. Both individuals and communities will be affected. When the number of users in the broadband network reaches 50-60% of the population, community type services will develop. The process may take some years but it is expected to happen as people more actively participates in the e-society.

In a test the accumulated PC traffic was monitored for a test period of 35 weeks. The results are given in Figure 1, it illustrates how the uplink and downlink traffic for the period varies [2]. It clearly shows a symmetric traffic pattern in the beginning of the period. At the end of the period the accumulated uplink is higher than the accumulated downlink. This is contrary to the expectations. The reason might be that people get used to the technology and utilizes the available possibilities. A typical service that generates higher uplink than downlink is the file sharing service.

This indicates that the traffic pattern may even move from asymmetric to symmetric and then back to asymmetric again, but then the opposite direction with more uplink than downlink traffic.

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Figure 1. Accumulated uplink and downlink traffic for a 35-week period [2].

2.4 Service development trendsThe number of electronic services, broadband technology and the auxiliary devices connected to the Internet increases fast, this is leading to more and more activities such as learning, purchasing, working, entertainment done through broadband services. The development of Internet has been in the past decade been enormous, but it is anyway still in an early stage of the Internet society, and the next step will be the evolution of the broadband society with its wide ranging and comprehensive scale of services.

Development trendsThe service development is mainly seen in the following areas: Broadcast related services Interactive data services (man-machine) Audio/video based individual/group type interactions. Introduction and breakthrough of IP

Telephony may be a first step in this direction. It offers flexibility and possibilities for extensions and development.

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Figure 2. The traffic patterns are changing from centralized to more group interactions.

The development of data communication is going from a centralized data interaction to more group interactions, see Figure 2. Beyond Triple Play, and when a majority of the households are connected, there will be a development of advanced audio/video/data services connecting individuals, groups of individuals (families, organizations, groups of students etc).

The traditional broadcast distribution will move towards more interactive services. Television and other broadcast type services will become integrated in the broadband service portfolios and continue to dominate with regard to transport volume people reached/served worldwide and the average amount on time spent watching during a day. This opens for a dominant role in worldwide information distribution, entertainment and associated business activities. Broadcast organizations will continue to play a dominant and extended multimedia role. The recent EBU $ 746M contract with the International Olympic Committee for broadcast rights for the 2010 and 2012 Games also provides for rights to other multimedia and mobile telephony services. Opposite, the availability of video, coding and storage equipment will also offer possibilities for local production and distribution.

Broadcast will develop into interactive broadcast, HD-TV will include sophisticated 3D effects and mobile/portable branch will develop. Portable TVs, TVs in cars and the handheld DVB-H as well as SDMB are examples from the starting phase of this development.

IP will gradually also dominate the distribution of broadcast content. DVB has through the DVB-IP development started a move in the IP direction and the Microsoft IP Television Software is being tested by European operators.

Driving forcesThere are probably two main driving forces for the service development: i) the availability of technology and ii) the density of users. New advanced and not to costly technology is the main driver for the individuals. The user will rely on four equipment groups; the PC, the TV(interactive), advanced IP telephony/conferencing and various types of mobile equipment. In addition there will be storage capacity and always on connection allowing for efficient use of multicast and IP telephony. The MOS based PC will continue to increase its capacity for at least 10 years becoming equipped with advanced coders/decoders and different types of processing equipment. Every home will have a common distribution and storage system for the different services used.

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For the community the main driver is the density of users. It is expected that the community type services will develop when the number of users in the broadband network reaches 50-60%. The process may take some years, but due to strong political parties wishing to create a functional and inclusive information society the development may go faster.

In addition to the driving forces mentioned above there are also other key factors. Some of them are:

Societal aspects Security and privacy User friendliness Copyright issues Introduction of secure and standardised payment services Overcoming the language barrier More use of radio and fibre in the last mile Cost effective interactive satellite solutions

New servicesNew services must be based on technologies that are available worldwide with strong support from both the computer and communication industries, including equipment manufacturers and service providers.

Broadcast and multicast services will be distributed in the different broadband networks. The Triple play development, delivering TV, Internet and Telephony with related services and all interactive, has started.

With a structure of high capacity broadband nodes covering a country, TV and other broadcast/multicast services will be distributed to these nodes through fibre connections and be available to the public in a flexible way in the local access network.

IP multicast will play an important role on the Internet in the coming years as new technologies/applications favouring multicast are introduced. Some examples of new services are:

TV distribution in local networks Media streaming services Peer-to-peer ad-hoc networks E-Europe type services, modern society for the future side

o E-learningE-learning refers to the use of multimedia technologies and the Internet to improve the quality of learning by facilitating access to resources and services as well as remote exchanges and collaboration.

o E-healthE-Health refers to the use of information and communication technologies to meet needs of citizens, patients, healthcare professionals, healthcare providers, as well as policy makers.

o E-governmentE-Government refers to the use of information and communications technologies to improve the efficiency, transparency and accountability of governments and municipal authorities. The goal is to improve services and information from the government to citizen and businesses by cooperation

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between different government agencies. E-government may offer shorter queues at public offices as well.

Many of the new service constellations like information distribution from authorities to the public (eEurope), multi-party interactions and data distribution, favours the use of multicast, but requires that reliable methods for multicast are developed and implemented. It is believed that the importance of multicast will increase as broadband coverage increases. The two main areas in focus are; development from the broadcast side to selected groups and as an addition on to two-way mobile communication services.

2.5 Network capacity and cost reductions Network capacityThe use of multicast in radio based access systems has several advantages. A common medium in the last mile is important. This will give more bandwidth to each individual user and thus the total capacity available will increase, leading to more and better service offers. It is likely that the capacity required would always adapt to or be higher than the available bandwidth. The capacity demand will develop in several ways. The electronics equipment in the home and office will improve and allow for higher volumes and data rates, the number of broadband users will increase fast, new service areas like community type interactivity and government type e-services will develop, and audio/video services will be stimulated by the availability of new cost affordable equipment. Thus efficient distribution methods like multicast would not only be an advantage but also a necessity.

Cost reductionsMulticast is an essential technology when there are user groups of considerable size that wants to receive the same contents in order to reduce the bandwidth need compared to unicasting the content. Multicast is of particular interest in low-capacity domains, such as corporate networks where the medium is shared and in domains with relative high bandwidth costs, such as satellite networks. Multicast would also help reducing the load on the sender. Multicast services have up to now been significantly more expensive than unicast services. Multicast is difficult to install and manage and is an expensive service. The cost are related to network deployment, installation of customer equipment, and management and maintenance. It is expected that when the number of users reaches a certain level the cost per user will be less for multicast than for unicast. For unicast each new receiver adds a constant cost, while for multicast the initial costs are higher but the cost of adding new receivers decreases as the number of receivers increase. However the use of multicast only makes sense when the bandwidth savings are larger than the deployment and management cost, and for large groups multicast should be a profitable and useful service.

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3. Technical solutions trends

The technologies to be used during the next 5-10 years are basically existing, but in addition there are technologies that may develop into important contributors. They are reviewed in this chapter on the European scenario.

3.1 Solutions for mobile accessThere is a strong consensus on the fact that one-to-many distribution is one of the hottest opportunities in 3G network economics, to deliver mobile rich content services to cellular end-users in a cost effective manner associated with Quality of Service under control. Several initiatives aim at providing one-to-many distribution services for 3G mobile networks. Among them, we have identified:

3.1.1 3G Cellular MBMS: Multimedia Broadcast Multicast Service

DescriptionThe MBMS is a unidirectional point to multipoint bearer service, which is being standardised by 3GPP. MBMS provides for data-grams transmission from a single source entity to multiple recipients in UMTS networks.3GPP has defined two operation modes: The broadcast mode is a unidirectional point-to-multipoint transmission of multimedia

data (e.g. text, audio, picture, video) from a single source entity to all users in a broadcast service area. The broadcast mode is intended to efficiently use radio/network resources e.g. data is transmitted over a common radio channel. Data is transmitted in the broadcast service area as defined by the network (Home environment).

The multicast mode allows the unidirectional point-to-multipoint transmission of multimedia data (e.g. text, audio, picture, video) from a single source point to a multicast group in a multicast service area. The multicast mode is intended to efficiently use radio/network resources e.g. data is transmitted over a common radio channel. Data is transmitted in the multicast service area as defined by the network (Home environment). In the multicast mode there is the possibility for the network to selectively transmit to cells within the multicast service area which contain members of a multicast group.

MBMS provides for two different services MBMS Download User Service: error-free transmission of files via the unidirectional

MBMS Bearer Services. Download Content is stored in the local files-system of the user equipment. The download is triggered by network as users are registered to the service.

MBMS Streaming User Service: continuous transmission of data and the immediate play-out via the display and/or the loudspeaker (multimedia data only). The session is triggered by the user

MBMS makes use of UMTS radio resources. It is ideally suited to deliver multimedia services to an audience geographically concentrated.

StatusThe standard is expected to be completed end of 2004 and implemented in release 6.

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3.1.2 Terrestrial broadcasting infrastructure

3.1.2.1 T-DMB: Terrestrial Digital Multimedia Broadcasting

DescriptionTerrestrial Digital Multimedia Broadcasting (T-DMB) rely on the Eureka 147 standard. The standard is promoted by the World DAB forum.T-DMB system targets reception by mobile, cellular handheld terminal and fixed receivers with a non-directional antenna. It can be operated at frequencies from 30 MHz to 3 GHz. T-DMB offers a general purpose digital multiplex which can carry a number of services, including video, audio-programme associated data and independent data services.

The T-DMB overall bandwidth is 1.536 MHz, providing a useful bit-rate capacity of approximately 1.5 Mbit/s in a complete "ensemble". Each service is independently error protected with a coding overhead ranging from about 25% to 300% (25% to 200% for sound), the amount of which depends on the requirements of the broadcasters (transmitter coverage, reception quality, etc.). T-DMB uses OFDM technology.

StatusT-DMB is going to open service in Korea mid 2005. It is based on DAB (Digital Audio Broadcasting) standard, which is deployed in 28 countries around the world.

3.1.2.2 DVB-T: Terrestrial Digital Video Broadcast

DVB-T is a multi-carrier system USING about 2000 or about 8000 carriers, each of which carries QPSK, 16QAM or 64QAM. QAM (Quadrature Amplitude Modulation) targeting receivers in homes, offices, cars, etc. The broadcast industry is promoting DVB-T technology to deliver video services to vehicular terminals moving at speeds up tp 170 km/h.

3.1.2.3 DVB-H: Digital Video Broadcast for Handheld terminals

DescriptionThis standard is described in “DVB-H 159 r9.2 DVB-H implementation guidelines”. It is based on DVB-T standard and implements specific features mainly to meet power consumption constraints, reception and mobility scenarios as well as propagation environments associated to handheld terminals.The network infrastructure consists in several very high power transmitters with on channel or frequency converter terrestrial repeaters to achieve coverage for mobile handheld reception. The system targets the delivery of Mobile TV services to dedicated receivers as well as cellular handheld terminals.

The network is expected to operate in the UHF band (474 – 698 MHz) in Europe. Note that the regulatory framework is still uncertain.It is able to offer theoretically a broadcast capacity from 5 Mbit/s (QPSK and code rate ½) up to 20 Mbit/s (16 QAM, 2/3 code rate).

StatusSeveral experiments are going on in UHF band in Finland, Germany with the Broadcast Mobile Convergence consortium as well as in France with TDF.Also a demonstration is carried out in USA at 1.670-1.675GHz.

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3.1.3 Satellite infrastructure

Several initiative have emerged around the world to provide multimedia services using an hybrid satellite/terrestrial repeater infrastructure to provide global coverage in a cost effective manner. This concept has been largely proved with XM radio system which operates since 2002 and has already reached 3 millions subscribers. It offers more than 100 radio programs and date services for 10 dollars per months over 100% of USA territory. The objective is to reach 5 millions of subscribers at the end of 2005.

3.1.3.1 SDMB in Asia

DescriptionAlso known as MBSAT, this system relies on a hybrid satellite / terrestrial repeaters architecture and operates in the 2.3 GHz frequency band. It aims at delivering Mobile TV services to dedicated receiver (DVD player size) as well as cellular handheld terminals.The satellite transmit a specific CDM waveform signal at 2.3 GHz band directly to the terminals and a TDM signal in Ku band to the terrestrial repeaters which convert to CDM signal in 2.3 GHz band.

The system offers a capacity of 30 video channel at 256 kbit/s. It covers Japan and Korea. Reception on handheld terminals is ensured under terrestrial repeater only.

StatusThe satellite has been launched in March 2004 and the terrestrial repeaters are under deployment. The commercial opening of the system will occur end of 2004.

3.1.3.2 SDMB in Europe

DescriptionThe purpose of the Satellite Digital Multimedia Broadcast system (referred as SDMB in the rest of the document) is to provide a datacast capacity for several mobile operators to deliver cost effective streaming and download datacasting services directly to mobile handsets over nation wide umbrella cells in both outdoor and indoor environments.

In addition, it aims at complementing 2G and 3G mobile system by achieving the true anywhere and anytime challenge with a dependable infrastructure offering point to point services capability via satellite over permanent or temporary zones not covered by the terrestrial networks. This requires a satellite uplink from the user terminal.

The system is designed to prevent introduction of constraints on the 3G cellular user terminal or operational constraints to the consumer itself. In other words, it shall be as transparent as possible to 3G handsets with respects to cost, autonomy, form factor, aesthetics to maximise market penetration. It is assumed that most 3G handsets will operate on both 2G and 3G type of networks.

The system relies on a hybrid satellite & terrestrial repeaters infra structure operating in the IMT2000 core frequency band allocated to Mobile Satellite Systems.

It makes use of the UTRA FDD WCDMA waveform in full compliance with the relevant 3GPP standard to allow a very low cost impact on the 3G handset bill of material. The system relies on a very high power geo-stationary satellite able to overcome indoor penetration constraints in rural areas.

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The system is able to offer a datacast capacity of 800 kbit/s per umbrella cell. This capacity can be upgraded up to 5 Mbit/s with enhanced features.

StatusIn Europe, several players of the mobile satellite industry and cellular industry are involved in the EC/IST FP6 MAESTRO integrated project to validate the system functions and performances. The concept has been proved with an experiment in Monaco as part of EC/IST FP6 MoDiS project.

SummarySeveral technologies are being developed to provide mobile broadcast services to cellular handheld terminals. Clearly there is a need for an additional infrastructure providing distribution services on dedicated radio resources to preserve revenues associated to cellular frequency bands. Several approach are considered either pure terrestrial or combined satellite/terrestrial infrastructure. The main issues which are currently being tackled are to define a business model enabling fair share of revenues between mobile operator and

content providers the deployment of this infrastructure the definition of an harmonised regulatory framework

Note that it is most probable that several mobile broadcast technologies will emerge and that they may complement each others in term of service offers or coverage for the benefit of the mobile users.

3.2 Solutions for fixed broadband access

3.2.1 DVB-IPI

A standard for the distribution of video over IP networks for end user distribution has been produced by the DVB-IPI group, and it is recommended that their practices are followed for such applications.

3.2.2 GSB

An aspiration of the MUSE project, outlined in the project proposal, is that the work of MUSE should be embodied in a set of specifications that could achieve a level of influence exemplified by GSM. The branding GSB is proposed for this concept. GSB should become a set of standards aiming at full specification of interfaces and protocols so as to ensure real interoperability from the home gateway to the edge across different network layers.

3.2.3 High Altitude Platforms as a new means of wireless broadcast/multicast delivery

Conventionally broadcast/multicast is delivered to the user using terrestrial wireless, satellite or cable/fibre delivery. A new delivery platform, the High Altitude Platform (HAP), is being developed by a number of projects worldwide, with FP6 CAPANINA project looking at the communications aspects of such deployments. HAPs are either solar powered airships or planes that will be located in the stratosphere at 17-22km altitude, and will serve users typically within at least a 60km diameter coverage area (larger areas are possible but will depend on frequency. Perhaps the simplest way to describe their advantages is that they are

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similar in terms of link budget to terrestrial wireless, but deliver the service in a similar way to satellite i.e. from above, with a regional type coverage area. Specific advantages include:

Small dish/antenna size – due to favourable link budget Local content – due to the regional coverage capabilities High definition TV enabler – again due to link budget and geometry Integration with high data rate point-to-point services – HAPs will offer a plethora of

high capacity broadband services from a common site (the HAP), with on-board storage of content and caching.

Fill in service – fill the gaps left in satellite coverage, or those badly served terrestrially due to topology, or temporary service, e.g. after natural disasters

3.3 Solutions for fixed and nomadic/mobile broadband access

Within the last decade, the multicast service model, where the one-to-many or many-to-many data communication method is described, has been implemented and tested at the Multicast Backbone Network (MBone). It has continuously been working to make multicast a ubiquitous Internet service. The Internet Service Providers (ISPs) have started to deploy multicast in their networks and most router vendors are now supporting native multicast routing. The network topology used up to now has been the flat topology, originating from the Mbone. This is now shifting towards a more hierarchical, globally multicast service infrastructure, used on the Internet, and is referred to as inter-domain multicast. The multicast routing protocols used by the ISPs are different for intra-domain multicast, which means within their own networks, and the inter-domain multicast support [3]. The inter-domain multicast is not extensively used yet, this can be observed from the Mantra monitoring tool. Instead an increased interest for Video and Television services using intra-domain multicast has been observed. A controlled transition to inter-domain multicast by first introducing intra-domain multicast could be the progress.

The main motivation for deploying multicast in the network is efficient resource utilization. This is in particular relevant with regard to bandwidth usage. Multicast reduces the overall bandwidth of content transmission since packet duplication only occur when paths to multiple receivers diverge, given that many end users receive identical data traffic. This is leading to an increased efficiency and is expected to influence positive on the development and deployment of multicast.In order to give some indication of the expected bandwidth savings due to multicast, the capacity demand for distribution of IPTV both with unicast and multicast has been estimated. In the calculation it is expected that each TV channel require a capacity of 5 Mbps. The results are shown in Figure 3.

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Figure 3 Capacity demand for unicast and multicast distribution of TV

The figure shows a significant improvement when multicast is used instead of unicast. This is a rough estimate of the multicast gain, but anyway it gives some indications of the achievements and a motivation for a faster development.

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4. Topics requiring new research results

IP Multicast communication has been supported for approx. 15 years in the Internet for fixed links. In such environments, a host joins a multicast group by using the Internet Group Management Protocol (IPv4) or the Internet Control Message Protocol (ICMPv6), in case of IPv6, to inform the local router. The local router in turn contacts other multicast routers and tries to create a multicast routing tree using a multicast routing protocol. In the earlier days of IP multicast, not all IP routers in the Internet supported IP multicast routing, hence a virtual overlay network (called MBone) was created. The MBone is connecting “multicast islands” together through tunnels which encapsulate IP multicast packets in IP unicast packets.

Applying multicast support to broadband wireless access networks can be difficult for the following issues [4]:

Issue Wireline multicast Wireless and mobile multicast

Possible solutions

Type of links Symmetrical and fixed characteristics.Broadcast links in LANs

Possibly asymmetrical and/or uni-directional links of varying performance and point-to-point links in cellular systems

Design of new protocols to handle route asymmetry and unidirectional links without reverse-path information

Bandwidth Plentiful Limited and variable Protocols to adapt membership management and routing updates to the amount of bandwidth available, and to user mobility

Topology Fixed Fixed in the backbone network.Highly dynamic in the access and ad-hoc networks

Protocols for both fixed and changing topologies by detecting topological changes

Packet Loss Infrequent (< 1%) Frequent and variable (1% - 30% based on link type)

Error control based on forward error correction or retransmission

Membership Changes

Only when user leaves or joins a group

Also when user moves to another location (nomadic access or mobility)

Protocols with reduced overhead for managing membership

Routing Fixed routing structure throughout the multicast session

Routing structure subject to change due to user mobility or path-diversity issues

Protocols that could dynamically adapt the routing to the current topology and available resources

Security Less complex due to fixed users and wireline links

More complex due to wireless links and possible use of broadcasting

Encryption and security techniques in routing and membership management

Quality of Service RSVP on individual routes

Due to user mobility, RSVP may cause excessive overhead

Design of new protocols for “soft” QoS under varying link conditions and mobility

Reliability Use of reliable multicast protocols (e.g. based on ALC)

More complex due to wireless links and user mobility

Design of new protocols that could allow different error correction techniques at one or more protocol layers

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4.1 Multicast Routing in Broadband NetworksBroadband fixed wireless access networks involve base stations and “switches” in the fixed topology as well as nomadic/mobile users in the wireless part of the network. While multicast routing in the fixed network part is fairly well studied, existing multicast routing protocols need to be adapted and/or modified to cope with the characteristics of wireless links (see the Table in 4.1). For example, Protocol Independent Multicast Sparse Mode (PIM-SM) can be used as the routing protocol, as it routes datagrams only based on the destination address, permitting a mobile host to send multicast packets from any point in the network.

Some research consist, for Wireline Broadband Networks to define and explain the multicast features positioning within two identified broadband access models which are called Ethernet-based network model (Layer 2 model), and IP-based network model, with introduction of IPv4 / IPv6 protocol and using Layer 2 or Layer 3.

In contrast, multicast routing for ad-hoc wireless networks allows for a high degree of mobility for all network components, and therefore multicast packets may not be routed correctly (or only sub-optimally) with protocols designed for fixed networks. The Internet Engineering Taskforce (IETF) installed the MANET group in 1998 to work on distributed and on-demand routing protocols. The proposed solutions are either based on multicast routing using a tree, or using a mesh based structure. In tree-based approaches, multicast routing uses a source-based or shared tree among sources and receivers. As such, only one path exists between any pairs of nodes. Hence, the multicast tree is subject to disruption due to link failures or user mobility. The second approach based on meshes provides multiple redundant routes for robust handling of link failures and node mobility, but suffers for problems such as looping and the increased amount of resources necessary to build the mesh.Protocols such as the Ad-hoc On-Demand Distance Vector (AODV) and the On-Demand Multicast Routing Protocol have been proposed recently, however further research is still required.For more details please refer to http://www.ietf.org/html.charters/manet-charter.html.

4.2 Quality of Service Multicast data within a network domain may be distributed to multiple receivers, so that the Quality of Service (QoS) cannot be associated to one user (host or mobile terminal) in particular. As a consequence, it seems natural to specify that the QoS should be defined (and reserved) per multicast service before service activation. Further complications arise from the nature of modern wireless links where the bandwidth in both forward and return links can be changed dynamically during an on-going multicast session (for example using Time Division Duplexing).

An application can adapt to the changing bandwidth by giving a feedback from the receivers to the source, in order to throttle the output rate of the source. However, these algorithms do not scale well to large groups of receivers. An alternative approach is to send the content on different multicast groups. Receivers can pick up as many channels as they are able to receive, to get the highest content quality that is possible for them. If the available bandwidth changes (e.g. due to bandwidth reallocation in the base station), the receiver may autonomously drop multicast channels – this does not disrupt the reception of the contents, but only slows down the receiving process.

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A framework for the so-called Application Layered Coding (ALC) protocols is currently being standardized within the IETF. However, a proper mapping of application data (e.g. video and audio), mobility-aware transport, and service scheduling is still subject to research.

Apart form the network level, QoS can also be defined at user level. In this case, quality is expressed or specified in user-meaningful terms such as tiling, blurriness, frames per second etc., usually measured on a sliding scale of satisfaction (e.g. excellent through satisfactory to poor). This is widely known as perceived QoS (PQoS). PQoS depends on the video encoding algorithm (H.261, MPEG-2, H.263, MPEG-4, MPEG/ITUT advanced video coding AVC etc) and the corresponding parameters (bit rate, frame rate etc), as well as on the end user terminal characteristics (screen size, color depth, resolution etc). In the broadcasting/multicasting world, PQoS is of equal importance to network QoS.

Furthermore, QoS has several characteristics, including dependability, availability and security, but the most important (and usual) concern the capability of the underlying delivery system to provide the user with a satisfactory experience (Quality of Experience – QoE). Ultimately, the end-user is the judge of QoS, and the system or service provider has to ensure the characteristics necessary to deliver that satisfaction. Additionally, it is expected that future multimedia services and networks will enable customers to select the QoS and the price of the desired service, in a flexible choice scheme that includes QoS level, tolerance and price for all possible choices at that particular customer end. In this respect, in the broadcasting/multicasting world, audio-visual content and multimedia services will be offered at various PQoS levels, and each end-user will join the appropriate multicast session, in which he/she will be registered (and paid for).

4.3 Reliable multicast transmission and scalabilityFor many applications, reliable multicast transmission is a basic requirement. Providing end-to-end reliability requires error detection and error recovery. The approaches followed by the Internet community so far are often based on either sender- or receiver-initiated retransmissions. In sender-initiated reliable multicast, receivers send a positive acknowledgement for each correctly received packet; timers can be used to detect packet loss at the sender. In receiver-initiated reliable multicast, receivers inform the sender about packet loss via negative acknowledgements.

In order to decrease the amount of feedback information from the receivers to the sender, either Local Recovery or Forward Error Correction (FEC) is used. In the local recovery scenario, a group of co-located receivers is clustered together and retransmissions are performed by neighbouring receivers. With Forward Error Correction techniques, not the original but forward error correction packets are multicast to the receivers for loss recovery. Due to the characteristics of the FEC codes (e.g. Reed-Solomon Codes, or Low-Density Parity Check Codes) in use, receivers with different loss patterns can correct lost packets with the same FEC information. This technique both saves bandwidth on the forward link (less retransmissions) as well as on the return link (feedback only needs to be per packet group, not per packet). For specific Video streams, because of the increase of the bandwidth transmission, some dedicated FEC schemes must be study in order to permit the best transmission of the video through the wireline/wireless broadband networks.

Besides reliability, an important issue in multicasting is the fairness between traditional TCP flows and IP multicast flows. As soon as TCP detects packet loss, it throttles its flow in order to be fair to other connections. In fixed networks, packet loss is considered as indication for

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network congestion, whereas in wireless networks packet loss may occur due to characteristics of the physical link. IP multicast flows in general are considered unresponsive as they often lack congestion control. To remedy this problem, the Reliable Multicast Transport group in the IETF is currently working on congestion control mechanisms applicable for multicasting. These mechanisms are primarily for fixed networks; adaptations for wireless networks need to be looked at. Further details can be found at http://www.ietf.org/html.charters/rmt-charter.html.

4.4 Secure multicast and digital rights managementSecurity issues in wireless multicast arise due to the risk of being eavesdropping the wireless links, the inherent broadcast nature of some wireless links and the use of flooding for tree/mesh construction [4]. The security risks include a complete loss of service, stealing and modification of private information, and the destructive modification of routing information. To address the security issues, four distinct mechanisms are needed: authentication, authorization, encryption and data integrity. Authentication is the process of forcing hosts to prove their identities so that they may be authorized to create, send or receive data from a group. Authorization is the process of allowing authenticated host to perform specific tasks. Encryption ensures eavesdroppers cannot read from the network. Data integrity mechanisms ensure that the datagram has not been altered in transit.

The current IP multicast service architecture does not mandate any authentication or encryption. Several possible solutions have been proposed in the Multicast Security working group of the IETF. However, most protocols are designed for fixed networks and do not, for example, address issues in the light of user mobility and membership changes. Further details can be found at: http://www.ietf.org/html.charters/msec-charter.html.Multicast requires support for a secure IP multicast service architecture, which is currently only specified to some detail. Further research is required both in terms of adapting existing standards to multicast capable networks, as well as making these standards efficiently work together with user mobility.

Digital Rights Management (DRM) addresses the issues of large-scale legal media distribution with the target of allowing consumers convenient use of digital media while equitably compensating other members of the distribution chain such as content creators, aggregators and vendors. DRM links specific user rights to media in order to provide persistent governance of user activities such as viewing, duplication, and access. If different media are distributed via broadcast/multicast, then the use of common handshake protocols to establish secured communication is unsuitable. Special algorithms for broadcast encryption are required [5]. These algorithms are subject to ongoing research. Furthermore, in a multicast environment, key management is essential and represents one of the most challenging aspects to design and implement for content protection and rights management.Another important and often neglected aspect is DRM interoperability. Research needs to be done, to evolve existing DRM systems towards interoperable, secure, media-related systems in a world of heterogeneous consumer devices, media formats, communication protocols and security mechanisms.

4.5 Future on-demand servicesWireless/wireline multicast is of great interest to Internet service providers, mobile telecom operators, content providers and businesses that require updates to multiple sites in parallel. Service providers can use multicast to support content-distribution services such as software

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distribution or distribution of audio- and video-related multimedia material. Businesses can use multicast to synchronize data in distributed databases.Future on-demand services based on wireless multicast and mobility could be [4]:

Application Description Multicast RequirementsMobile auctions, interactive games, financial services

Allow users to buy or sell certain items using multicast support of the wireless infrastructure

Security and reliability. Fast group management

Mobile and location based advertising

Allows turning the wireless devices and infrastructure into a powerful marketing medium

Asymmetric non-real-time multicast. Must scale to large groups

Mobile Entertainment Services, Mobile Distance Education,Flash mobs

Allows providing entertainment services to users on per-event or subscription basis

High bandwidth with low delay. Service interruptions are not tolerable.

Proactive Service Management Allows trying to provide users information on services they will need in the future

Asymmetric non-real-time multicast. Response time of minutes is tolerable.

Product Recommendation Systems Allows users/businesses to receive recommendation of various products and services from third parties

Asymmetric non-real-time multicast. Privacy may be an issue.

Research will be required for analyzing the specific requirements of these new applications.

4.6 Local storage and local cachingMany well-known applications can benefit when multicasting is used. For example, the latency perceived when using the World-Wide-Web can be drastically reduced using multicast peer caching. With multicast peer caching, local caches at the receivers are updated periodically (or upon request) via multicast and thus always contain the newest content. The idea is to design the content of the local caches such that most of the requests from the users can be satisfied from the cache. This improves the user’s surfing experience while decreasing the individual’s bandwidth requirements both on forward and return links. Mobile users can be supported by allowing them to take snapshots of local caches whenever they are in reach of a wireless network. Future research issues in this field are content scheduling and cache updating strategies, as well as standards for caching dynamic web content.

A high altitude platform architecture has an ideal central point for the physical location for storage of content and caches, specifically the HAP itself. CAPANINA is examining the merits of creating a library of most frequently requested content as a way of reducing the capacity and availability requirements of backhaul communications, caused by limited availability (e.g. due to rain and other forms of outage) on the communications links. Work underway within the CAPANINA project is looking at IP Multicast as means of exploiting broadcast/multicast in such situations. The merits of locating of storage/caches at multiple points within a HAP network is under consideration, i.e. user, HAP, wider network, and will take into account reliability update frequency, delay etc.

4.7 Fair Share of Revenue using multicastA major issue is providing multicast communication facilities to wireless/wireline users along with appropriate business and pricing models that allow for a fair share of revenue. In [4], an overview over possible solutions for pricing wireless multicast is given.

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Pricing Solution CommentsFlat-rate Simple to implement but unfair to some customersBased on packet counting Need to count packets, even when multiplying over certain linksBased on the number of participants Simple to implementBased on session duration Simple to implement but unfair to some customersBased on type of link, distance More accurate pricing and more complex to implementBased on session duration, participants and packets

More accurate pricing and more complex to implement

Time-sensitive Simple to implement, hinders some applications and services

Another issue is finding an appropriate pricing solution for each individual multicasting application is the distribution of revenue between different service providers that may be involved in providing a single multicast session.

Distribution of Revenue CommentsRatio of distance travelled in individual networks

Difficult to implement

Number of packets and number of copies made in individual networks

Need to count packets, even when multiplying over certain links

Number of routers used Requires counting the number of routers for every packetNumber of links in individual network Requires counting the number of links for every packetNumber of customers of a network in the session

Easy to implement

A combination of these factors More accurate but difficult to implement

While pricing is more or less a decision taken by the individual multicast service provider, the sharing of revenue requires exchange of traffic information and therefore standards by official bodies such as the IETF. As to our knowledge, no activities are currently underway.

4.8 Spectrum efficiency including RRM Radio resource management and spectrum efficiency are of critical importance when deploying a large scale wireless system. The efficient support of IP multicast applications requires system optimizations as discussed next.

4.8.1 BFWA

Multicasting is considerable more efficient, both in terms of spectrum efficiency and software processing, when a sub-network explicitly supports it, [6]. For example, if a router forwards an IP multicast packet on to a shared radio channel in a wireless access network, it needs to send only one copy of the packet no matter how many members the multicast group has on the wireless channel. On these networks, multicast is basically broadcast on the medium, with Layer-2 receiver filters. To support efficient HW filtering of the multicast traffic, the Layer-2 addressing scheme must have multicast functionality.On a wireless network using Adaptive Coding and Modulation (ACM) users with good receive conditions may be told by the Radio Resource Management to use a more spectrum efficient burst format, while users with worse receive conditions are allowed to use a more robust burst format. The multicast traffic must be transmitted on the most robust burst format that is used within the group. For example, if the data for a specific multicast group is transmitted using a very spectrum efficient but less robust burst format and there is a new member with poor receive conditions, then the multicast content for this group must be switched to a more robust and less spectrum efficient burst format if the new member is allowed to join the group. In sub-networks using ACM multicast will be more spectrum efficient than broadcast since broadcast needs to be transmitted on the most robust burst

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format used within the system, while multicast content only needs to be transmitted on the most robust burst format used within the group. The BROADWAN project investigates in these research topics.

4.8.2 High Altitude Platforms

Another method to significantly enhance spectrum efficiency is the use of High Altitude Platforms (HAPs). They will allow frequent resource reuse controlled by the antenna beamwidths producing the footprints and number of footprints (cells) per platform, which when intelligently used with appropriate broadcast/multicast techniques can significantly enhance spectrum efficiency. For a given antenna beamwidth, cells are approximately 1000 times smaller than on a GEO satellite owing to the HAP’s nearness to the ground. Spectral efficiency is further enhanced by exploiting the highly directional user antenna, which will enable multiple HAPs to serve a common service area with the same spectral allocation [7]. Such configurations could also enable multiple broadcast/multicast streams to be received by a user from disparate sites.

4.8.3 3GPP Systems

Radio resource management also forms an integral part in 3G all-IP mobile networks. However, some of these techniques need to be re-evaluated in order to better support broadcast and multicast. Some of the research related issues are considered below:

TR 25.992 requires that data loss during cell change should be minimal during handover. In other words, when a UE in a MBMS session performs a handover, it should be possible to provide service continuity to this UE. Existing handover algorithms do not meet the requirements for providing seamless handover for multicast groups whose members are mobile. Further research is required for this topic.

Another issue is power control in order to maintain an acceptable Signal-to-Interference Ratio (SIR), as all signals in UMTS are sharing the same bandwidth and are overlapping in time. Using power control, each Node-B may transmit using the minimum power needed for maintaining the required SIR ratio, thus diminishing power consumption. In the current standard the point-to-multipoint channel is the Forward Access channel (FACH) where power control is not enabled. A research option for a point-to-multipoint channel is to use the Downlink Shared Channel (DSCH) where power control is possible. Thus, one of the UTRAN enhancements in order to provide a spectrum efficient multicast service is to investigate if and under what conditions power control should be used in the multicast channel. Using power control aids in minimising the high power requirements and helps to reduce the interference; hence it increases the capacity of the system. 3GPP has proposed Forward Access channel (FACH) as a transport channel for MBMS, although Downlink Shared Channel (DSCH) can be another valid option as a transport channel for MBMS. The advantage of DSCH over FACH channel is that DSCH channel has inner-loop power control with the power control command sent every time slot. However, it is has been shown that when the number of users increases, the benefits of using DSCH are not clear, i.e., the gain of using DSCH diminishes as the number of users increases. So, when the MBMS group size is large, a simple FACH channel without dynamic power setting may suffice. The uplink feedback channel could be either dedicated uplink or shared (RACH) channels. It allows low data rate transmission, although it has limited capacity. Further studies are required.

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4.9 End-user requirements The users of broadband networks and services represent the widespread interests of the population as a whole, the business world, different groups and organisations and government at all levels. They all expect to have access to any service within their area of interest in a flexible way and at low cost. For the private user group this is now creating a demand for Triple Play including VoIP and flexibility in selection of entertainment. A major concern in large user groups is that they may be left behind as part of the digital divide problem. With a majority connected to broadband this creates a need for increased network capacity in total as well as for the individual users at all locations.At the other end of the user scale governments are pushing for use of broadband in operating, developing and reforming the different functions of society.User demands are now pushing on the operators and bring forward limitations in existing networking like the DSL possibility to support Triple Play in combination with high return capacity, the problems of having more than one TV supported from a transport stream set top box system with limited freedom of simultaneous operation on different transport streams.A main user demand today is efficient in house provision of combined services without numerous network connections and boxes. The Triple Play demands will strongly influence on network development. The fixed telephone network turns into a fixed broadband network with VoIP, meaning also that broadband will have to cover all expenses. The pure MPEG based broadcast networks must adapt to IP and multimedia interactivity. Facing demands for growth in individual use as well as a rapidly increasing number of users, operators have to look for possibilities for resource sharing and cost reduction. Broadcast and multicast with varying degrees of interactivity may offer important contributions in this connection if properly developed and employed.Other issues of importance for the users are availability of services, security and training (education) in using the services.Availability is considered to be an advantage of Internet, but for the broadcast type information/entertainment domain the distribution control of the most attractive content areas are more and more being bought and controlled by some economically strong distributor. A “Pay per view” system for the future IP broadcast/multicast systems could be a solution to this problem. Users expect that their broadband connection will give them full access at acceptable cost.Security is a real concern for most users; it involves privacy, and secure operation in economical transactions. Extended use of multicast leads to an always on requirement, for many users an added risk that will have to be handled in connection with IP-telephony. Implementation of security is a problem for many users. They want a secure broadband connection, not just a connection open for bugging, viruses and worms.Training for efficient and reliable usage is an area that can be supported by interactive broadcast/multicast.

4.10 Digital switchover Digital Switchover (DSO), i.e. the transition from analogue terrestrial to terrestrial digital video broadcasting (DVB-T), is an issue (among the others) that has been considered by the Sevilla European Council, 21-22 June 2002, as a key and critical element towards the establishment and successful deployment of Information Society (IS) all over Europe. This consideration along with the proposed actions aims to stimulate secure, applications and content based on a widely available broadband infrastructure. Terrestrial Digital Video Broadcasting (DVB-T) is a multi-carrier system mainly used for broadcasting "bouquets" of digital TV programs to a large number of viewers scattered over

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large geographical areas (i.e. metropolitan territories). DVB-T supports fixed, portable or even mobile reception. The intrinsic characteristic of DVB-T to combine heterogeneous traffic (e.g. MPEG-2 based audio/video streams and IP services) into a single transport stream enables the usage of DVB-T as the “last mile” technology. Taking into account the networking capabilities and broadband access potentialities of the new digital television (based on the proper adoption of DSO), DVB-T may constitute the basis of a broadband access infrastructure, capable to interconnect intermediate distribution nodes (via which users/citizens access it), accommodating real interactive and on demand services, multicast and broadcast applications.

DSO is strongly related (and/or implies) to a number of implications in the spectrum policy. So far and in respect to the above issues and the proposed actions, a series of activities has been elaborated (or still are under way) under the European Commission’s surveillance, ranging from R&D actions, coordination/support activities, studies [8][9] and reports (both in the framework of 5th and 6th Framework programme) to a number of public hearings and consultation meetings [10][11]. The aim of these actions/activities was (and still remains) to provide results that will contribute towards the establishment of common legal/political/ technical/economical frameworks, jointly adopted and abided by all member states. The DSO issue along with the spectrum policy have strong impact over many aspects:

the frequency dividend (releasing of part of the UHF band); the nature of the new digital television and the IP applications confronted by it; the synergies among broadcasting and mobile technologies including the broadband

mobile applications over 3G, B3G, DVB-H the stand alone use of UHF band by mobile operators, converging Internet applications

and services the IP television, IP multicasting/broadcasting the local and networking aspect of the new terrestrial television (at social and cultural

level)

A common spectrum and digital switchover policy has strong impact over many aspects: the contradicted business interests between the broadcasting and telecommunication

sectors, each country's legalisation individualities and market exceptionalities, and the un-clarified and unexplained technological advantages of digital broadcasting in

UHF in creating IP broadband access infrastructures in synergy with broadband mobile.

New research results will contribute to the issues of DSO and Spectrum Dividend, showing a way of defining specific actions/activities and providing results that will contribute towards the establishment of common European successful frameworks.

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5. Roadmap 10 years ahead

This chapter refers to the evolution of the networks in Europe over the next 10 years, Taking into account the migration scenario from ATM to pure IPv4/IPv6 IP links. It also deals with the evolution of multicast/broadcast in wireless/wireline broadband networks, and with the Triple Play and beyond.

5.1 Migration from connection oriented (ATM) to connection less networks

It is generally recognised that ATM will be gradually replaced by Ethernet at layer 2 as overlay or replacement around 2007. Ethernet will become more dominant in the regional and aggregation networks between the edge and access nodes (e.g. DSLAM). But around 2007 rather Ethernet uplink interfaces than pure Ethernet DSLAM’s exists.

The drivers for this technology transition are the expected increasing bandwidth demands especially for new video and data services, advantages in scalability and statistical multiplexing, the convergence of services, less overhead and cost benefits as the most important one. Ethernet handling functionalities will be introduced either by implementation at existing network elements or by introduction of new Ethernet switches. For services like business data-services ATM may be further used, but only as pure transport technology between L1/L2 (e.g. EoATM –AAL5 or EoSDH for aggregation purposes).

By 2010, optical Ethernet layer 2 technologies will be predominant in the regional and aggregation networks with improved functionalities to set policies for services on top of the basic internet service. Depending on customer type and service offering a mixed layer2/3-Eth./IP based access network will be implemented by some operators for instance for layer 3 based network services (e.g. L3-VPNs like VPRN). Optical Ethernet and EoVDSL will gradually extent towards the first mile network between access node and CPE by some operators, due to the adoption of Ethernet and IP principles.

5.2 Introduction of IPv6 Europe seems to be split in IPv6 believers and more conservative followers. The believers see an introduction of IPv6 services in a timeframe of 2007-2010. Address exhaustion is seen as the main reason in those countries, mainly because of All-IP mobile (including remote sensor networks and automotive) and always-on fixed access services. Conservative followers do not see a compelling reason to introduce IPv6 – there are still sufficient addresses for a long time or there are fixes in IPv4 to overcome the problems with IPv4. Nevertheless, also many conservative followers prepare themselves via pilot-trials or tendering for IPv6-ready equipment.

5.3 Evolution of Multicast and Broadcast in Broadband NetworksIn Wireline Broadband Networks, It is generally recognised that ATM will be gradually replaced by Ethernet at layer 2 as overlay or replacement around 2007. Ethernet will become more dominant in the regional and aggregation networks between the edge and access nodes (e.g. DSLAM). But around 2007 rather Ethernet uplink interfaces than pure Ethernet DSLAM’s exists.

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The drivers for this technology transition are the expected increasing bandwidth demands especially for new video and data services, advantages in scalability and statistical multiplexing, the convergence of services, less overhead and cost benefits as the most important one.

Ethernet handling functionalities will be introduced either by implementation at existing network elements or by introduction of new Ethernet switches.

By 2010, optical Ethernet layer 2 technologies will be predominant in the regional and aggregation networks with improved functionalities to set policies for services on top of the basic internet service.

Depending on customer type and service offering a mixed layer2/3-Eth./IP based access network will be implemented by some operators for instance for layer 3 based network services (e.g. L3-VPNs like VPRN).

Optical Ethernet and EoVDSL will gradually extent towards the first mile network between access node and CPE by some operators, due to the adoption of Ethernet and IP principles.

In the specific case of broadcast multicast evolution, the status in 2004 is that TV is distributed via radio or coaxial cable. There are some trials of TV distribution over IP networks mainly driven by the video on demand services. IP Set-top-boxes are currently commercially available.

In 2007, the majority of contributors believe that some form of multicast or broadcast functionality will be available in the nodes and commercial deployment of PPV and VOD will start.

For this, some evolutions in the current network will have to take place to guarantee more downstream bandwidth and functionalities like IP multicast or any new process of packet replication as also an increment of intelligence both on the central office equipment and CPE.

In 2010 the solutions will be redesigned to follow the potentialities of the network and standards. Also by this time, the users will be able to generate this type of traffic with gaming, other peer-to-peer traffic and broadcast of multimedia.

In terms of Video-on-demand is expected a distribution of the video servers to reduce the usage of the core and access network as much as possible.

This type of functionalities will start in limit zones around 2007 and will be spread to wider zones in 2010.

5.4 Triple Play and beyondIn the future years, the majority of Telco and cable providers believe that some form of multicast or broadcast functionality will be available in the nodes and then commercial deployment of PPV and VOD/NVOD applications will start. For this, some evolutions in the current access network will have to take place to guarantee more downstream bandwidth and functionalities, like IP multicast or any new process of packet replication as also an increment of intelligence both on the central office equipment and CPE.

Providing Video over broadband IP compels expectations from different Operators to access new markets. For the Telco expectations, « Triple-play » services offer permits to compete

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with Cable Operators. From the DTH and Cable operators expectations point of view, this new deploiement permits to address customers who cannot be reached in down town cities, and also it is a new architecture to permit to provide VOD, NVOD services and other new interactive services.

But providing this new market, some requirements are necessary:The Bouquet operators request for Broadcast quality video,New players request for lower cost solutionDecrease BW as much as possible, target 1Mbps, to increase the number of accessiblesubscriber or increase No. of channels per home.

These expectations are the conditions to permit an acceleration of the deployment of such a broadband IP deployment where multicast become a necessity. For digital service providers and cable providers, the "triple play" represents the ultimate way to increase profits and customer loyalty at the same time. This combines Voice over IP, Speed Data and Video services. This has already emerged, and already proven successful.

To increase the number of accessible subscribers and the number of received channels Broadcast quality video is required (between 1.5 and 2.5 Mbps for SD) Encoding technology is moving from MPEG-2 to MPEG-4 MPEG-2 to MPEG-4 transcoding needs is also emerging

In parallel, some feature regarding the global architecture will evolve: it is a reality that IP Setup Box cost is decreasing To compete with cable and DTH: HD MPEG4 over ADSL2+/VDSL is a

competitive solution Content has to be protected: scrambling and CAS systems are required (DRM)

The offer is a mix of Live TV and VOD

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6. Inputs for standardisation and regulation

6.1 Technology independent multicastVirtually, Multicast could be provided on any network providing reach to a numerous population of users. This variety of networks exists, and will increase in the future. Nevertheless, the networks on which multicast may develop are not often built for multicasting purposes: the wireline telephone network, cellular networks, etc. Until recently, the associated regulatory regimes were often tailored to deal with the original use of the network, resulting in technology-oriented regulations.

In this context, the “technological neutrality” policy adopted by the European Union is an important advance in allowing technology independent services to develop, thus enabling a critical size for such markets to develop. The “Telecom package” adopted in 2002 and implemented in 2003 is clearly a critical step. It introduces the concept of “Electronic communications” and makes the regulation of those communications independent from the technology. The implementation of the associated directives by E.U. member states is of crucial interest for Multicast applications, since regimes may or may not vary from one country to another. This is of particular relevance for services targeting very wide audiences, extending beyond national borders.

It is interesting to note that the new package allowed to modify, and sometimes to clarify the role of regulatory authorities in member states (content regulation, telecom regulation). The position of multicast in this panorama is clearly on the boundary between telecom and broadcast. A higher visibility of Multicast applications, whichever the technology used, of nature to help regulators understand the particulars, and establish appropriate frameworks.The review of Television Without Frontier Directive may also occur in the foreseeable future. This may, to some extent impact the regulatory environment for Multicast services.

6.2 International standard bodiesBroadcast and Multicast services are covered by several standard bodies, some belonging rather to the broadcast world and other from the telecommunication world, even if they tend to merge.The major Broadcast standard body is DVB. Within DVB, all types of broadcast are covered, including satellite, cable and terrestrial. Recently, standardisation process has started for broadcast and multicast applications to mobile and handheld terminals. Standardisation deals with physical and access layers (DVB-h) and with network layers (DVB-CBMS).

Within the mobile wireless world, several bodies are focusing on broadcast and Multicast, including IMT 2000 (3GPP and 3GPP2), OMA, 802.11 (WIFI) and 802.16 (WIMAX).In particular, the MBMS, as part of 3GPP, is addressing these specific features.OMA has initiated a specific working group (OMA-BCAST) to analyse all aspects of the broadcast and multicast services, including authentication, billing and digital rights management (DRM).

The work in DVB is gradually linked with IETF. Both the DVB-H and the DVB-IP recommendations are strongly dependent on IETF recommendations.The IETF has several working groups related to multicast standardization issues:

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The Reliable Multicast Transport (RMT) groups works on a framework (called building blocks) for reliable multicast transport protocols with the aim of ensuring interoperability

The Multicast & Anycast Group Memebership (MAGMA) group works on group membership related issues and defines protocols between end-host and the multicast routers on the same subnet.

The Inter-domain Multicast Routing (IDMR) group and the Protocol Independent Multicast routing (PIM) group focus on scalable multicast routing algorithms

Finally the Multicast Security (MSEC) group looks at securing multicast transfers over the Internet and at efficient key exchange protocols for IP multicast.

6.3 Spectrum issues and related bodiesSpectrum issues are of particular relevance for multicast applications targeting mobility. Spectrum regulation is in general subject to national sovereignty. However, it is recognised generally that the harmonisation of the spectrum usage among countries is beneficial for limiting interference issues, to create economies of scale for equipment to operate in a wide range of countries.The highest level of regulation is the International Telecommunication Union. The ITU allocates spectrum to services on a worldwide basis. ITU has pre-defined services such as Fixed, Mobile, Mobile-satellite, Broadcasting, Broadcasting-satellite, etc.The Broadcast spectrum is usually “planned” at the international level. It is worth noting the replanning of the UHF Television spectrum is on-going for Europe, Russia and Africa. This work should result in the possibility to introduce on a wide-scale Digital Television.But Broadcast applications do not always rely on spectrum identified for Broadcast by the ITU. Satellite television is a good example, particularly in Europe, as it uses Fixed-Satellite-Service frequency bands. Similarly, Mobile Broadcast pilot networks are developing in various frequency bands: Broadcast (DVB-H/T based networks), Mobile Satellite (S-DMB) and Mobile (3G/MBMS). New technologies tend to blur the distinction between services. For multicast applications, it is a key that the original allocation of the band shall not be an artificial barrier to develop the services.

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7. Conclusions

Broadcast and multicast in broadband access networks increase spectrum efficiency and facilitate the information based broadband community. Since larger bandwidth always cost more, particularly in the access network, effective implementation of broadcast and multicast have a direct impact in providing every citizen with affordable broadband access. An active engaged population will use technology for peer-to-peer broadband communications, and it will presumably increase in the future as the broadband take ratio passes beyond a critical mass of about 60%. Broadcasting networks develop towards higher degree of interactivity with satisfactory high capacity return channels, thus providing coverage everywhere as well as two-way communication means.

A number of research challenges have been identified such as routing, QoS, security, and reliability. Also the on demand services and fair revenue share will be addressed. The issue of spectrum efficiency and the role of local storage are important research areas. The switch-over from analogue to digital television raises many issues such as the digital divide and traditional broadcasting now offering a two-way technology.

A road-map has been worked out for a period of about 10 years ahead. It is believed that Ethernet will more and more dominate over ATM and services will be available as triple play for the end user. The integrated traffic is symmetric, but with temporarily large asymmetries. The features provided by broadcast and multicast are implemented and secure specified quality services are provided either the user is fixed or mobile.

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References[1] IETF RFC 3170 - IP Multicast Applications: Challenges and Solutions,

http://www.faqs.org/rfcs/rfc3170.html[2] P Bakki, J Bitó, L E Bråten, L Chira, Zs Elek (ed.), M Goldhammer, M Hauschild,

L Henden, G Horváth, H Linder, A Mayer, T Montalant, A Morozova, S Nagar, A Nordbotten,T Palade, D Salazar, W Sánchez, J Schmidbauer, M Schmidt, J Seseña, I

Tardy, K Würflinger, User and Service requirements, BROADWAN Deliverable D6, 30 April 2004.

[3] K. Almeroth, “The evolution of multicast: From the MBone to inter-domain multicast to Internet2 deployment,” IEEE Network, January/February 2000.

[4] U. Varshney, “Multicast over Wireless Networks”, Communications of the ACM, Vol. 45, No. 12, December 2002

[5] References for Broadcast Encryption: http://calliope.uwaterloo.ca/~jiangshq/broadcast.html

[6] IETF RFC3819, Advice for Internet Subnetwork Designers, http://www.faqs.org/rfcs/rfc3819.html

[7] D. Grace, J. Thornton, G. Chen, G.P. White, T.C. Tozer, Improving the System capacity of Broadband Services Using Multiple High Altitude Platforms, IEEE Transactions on Wireless Communications, (TW03-354), Accepted January 2004 or D. Grace, G. Chen, G.P. White, J. Thornton, T.C. Tozer, Improving the System Capacity of mm-Waveband Broadband Services Using Multiple High Altitude Platforms, IEEE GLOBECOM 2003, December 2003

[8] Digital switchover in broadcasting’ a document was created on behalf of the European Commission (Directorate General Information Society) provided by BIPE consulting and which was the subject for a public hearing organised by DG A1 (June 2002).

[9] “Study on Interoperability, Services Diversity and Business Models in Digital Broadcasting Markets”, February 2003. A study that has been commissioned to OXERA (Oxford Economic Research Associates) by the European Commission, on “Interoperability, Service Diversity and Business Models in Digital Broadcasting Markets”, in order to help inform Commission policy towards digital broadcasting as the sector grows and matures.

[10] “Public consultation on the study on Digital Switchover in Broadcasting”, 1st July 2002, organised by DG Information Society A1.

[11] “Barriers to widespread access to new services and applications of the information society through open platforms in digital television and third generation mobile communications”, February 2003, organised by DG Information Society A1.

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Annex 1 Projects provided contributions and comments ATHENA B-BONE BROADWAN CAPANINA MAESTRO MUSE

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Annex 2 List of participants in the Broadcast and multicast cluster (bmc@nta.no)

Name Project Affiliation EmailPeter Stuckmann DGINFSOD1 peter.stuckmann@cec.eu.intEvangelos Pallis ATHENA Center for

Technological Research of Crete

pallis@iit.demokritos.gr

Pierre Vasseur ATHENA Thales pierre.vasseur@thales-bm.comTasos Kourtis ATHENA Demokritos kourtis@iit.demokritos.grManuel Dinis B-BONE Portugal Telecom

Inovacaomdinis@ptinovacao.pt

Chris Howson BROADWAN Thomson christopher.howson@thomson.netHilmar Linder BROADWAN University of Salzburg hlinder@cosy.sbg.ac.atLars Erling Bråten BROADWAN Telenor lars-erling.braten@telenor.comLisa Henden BROADWAN Telenor lisa.henden@telenor.comTerje Tjelta BROADWAN Telenor terje.tjelta@telenor.comTorunn Flo BROADWAN Nera torunn.flo@research.nera.noJean-Noël Patillon BROADWAY Motorola patillon@crm.mot.comDavid Grace CAPANINA University of York dg@ohm.york.ac.ukRiccardo Pascotto DAIDALOS T-Systems/DTAG riccardo.pascotto@t-systems.comHans-Jürg Vögel DAIDALOS/GST BMW Group

Researchhans-joerg.voegel@bmw.de

Folie Neri EPHOTON-ONE Politechnio di Torino neri@polito.itChristophe Selier MAESTRO Alcatel Space christophe.selier@space.alcatel.frNicolas Chuberre MAESTRO Alcatel Space nicolas.chuberre@space.alcatel.frLaurent Combelles MAESTRO Alcatel Space laurent.combelles@space.alcatel.frAlessandro Vanelli MAESTRO University of Bologna avanelli@deis.unibo.itGiovanni E. Corazza MAESTRO University of Bologna gecorazza@deis.unibo.itBjörn Wüst MCDN University of Kassel bjoern.wuest@uni-kassel.deKlaus David MCDN University of Kassel david@uni-kassel.deMarco Fratti MOCCA Motorola marco.fratti@motorola.comFelix Strohmeier MOME Salzburg Research fstrohmeier@salzburgresearch.atHerve Le-Bihan MUSE Thomson herve.le-bihan@thomson.netSylvie Danton MUSE Thomson sylvie.danton@thomson.netJohannes Peltola PHOENIX VTT johannes.peltola@vtt.fiJuan Ramón López SATLIFE Hispasat jrlopez@hispasat.esMarkus Werner SatNEx DLR markus.wernes@dlr.deFilomena Del Sorbo SatNEx German Aerospace

Center (DLR)filomena.delsorbo@dlr.de

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