Deliverable D2 IST-2000-26418 Technology Catalog (Draft ... · Access Networks Working group...

IST-2000-26418

Access Networks Working group

Deliverable D2 Technology Catalog

(Draft)

Project Number: IST-2000-26418

Project Title: NGN Initiative

Activity title: Access Networks

Deliverable Security*: PU

NGNI Deliverable Number: D2

Contractual Date of Delivery to the NGNI: 31.10.2001

Actual Date of Delivery to the NGNI: 31.11.2001

Title of Deliverable: Technology Catalog (Draft)

Work package contributing to the Deliverable: Access Networks working group

Type of Deliverable**: R

Authors : F. Jacquier (ResCom), P. Lorenz (UHA), A. Andritsou (Intracom), E. A. Sanchez (Robotiker)

Review: Y. T’joens (Alcatel), J. Sanchez (Lucent), A. Kapovits (Erurescom), S. Rao (Telscom)

* Security: PU – Public, PP - Restricted to other program participants (including the Commission Services) RE - Restricted to a group specified by the consortium (including the Commission Services) CO - Confidential, only for members of the consortium (including the Commission Services)

** Type: R - Report, P - Prototype, D - Demonstrator, O - Other

Abstract: This second deliverable from the Access group addresses the access network technology themes selected in the deliverable 1 and expands each of these technology status from the vendor, market and advantages to the customer point of view. The subject is very vast and compilation of results from various sources is attempted. The technologies addressed are summarized for the benefit of readers to understand the cost-benefit analysis. The next deliverable will expand on this with additional next generation technologies, ongoing standards activities and trends. Keywords: Access Networks, Technologies, standards, regulation, evolution, market trends

NGN Initiative: Access Networks Tuesday, September 04, 2001 AN-D1v4.doc - 1 -

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Table of Contents

1 INTRODUCTION............................................................................................................................... 5

2 ACCESS NETWORK SOLUTIONS.................................................................................................. 7

2.1 Access Network Architecture ....................................................................................................................7 2.1.1 Star / Multi-star networks .....................................................................................................................7 2.1.2 Tree and Branch Networks ...................................................................................................................8 2.1.3 Bus Networks .......................................................................................................................................8 2.1.4 Ring Topology......................................................................................................................................8 2.1.5 Mesh Networks.....................................................................................................................................8

2.2 Technologies addressed..............................................................................................................................9 2.2.1 Copper networks...................................................................................................................................9

2.3 Technologies to be addressed...................................................................................................................21 2.3.1 Copper networks.................................................................................................................................21 2.3.2 Wireless networks...............................................................................................................................23 2.3.3 Fiber Optic Networks .........................................................................................................................23

2.4 UMTS / IMT-2000 ....................................................................................................................................25 2.4.1 What is UMTS (IMT-2000) ?.............................................................................................................25 2.4.2 Benefits offered by UMTS .................................................................................................................26 2.4.3 UMTS deployment .............................................................................................................................29 2.4.4 UMTS access......................................................................................................................................30 2.4.5 Key technologies for UMTS...............................................................................................................40 2.4.6 European projects ...............................................................................................................................43

2.5 Cable Access Networks ............................................................................................................................45 2.5.1 Introduction - Cable TV Networks ....................................................................................................45 2.5.2 Cable Modem Access Networks.........................................................................................................45 2.5.3 Cable Access Network Architecture...................................................................................................47 2.5.4 Introduction to Data Over Cable Systems ..........................................................................................50

2.6 Optical Ethernet .......................................................................................................................................51 2.6.1 Overview ............................................................................................................................................51 2.6.2 Competing Technologies ....................................................................................................................52 2.6.3 Cable modems ....................................................................................................................................53 2.6.4 Satellite Systems.................................................................................................................................53 2.6.5 LMDS.................................................................................................................................................53 2.6.6 38 GHz radio ......................................................................................................................................53

2.7 Third-generation mobile communication systems.................................................................................54 2.7.1 Introduction ........................................................................................................................................54 2.7.2 The IMT-2000 concept .......................................................................................................................54 2.7.3 Mobile Data Services and Applications..............................................................................................55 2.7.4 3G Data Rates.....................................................................................................................................56 2.7.5 Relevant players .................................................................................................................................58


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2.8 Fast Ethernet.............................................................................................................................................60

2.8.1 Signaling issue....................................................................................................................................60 2.8.2 Hardware ............................................................................................................................................60 2.8.3 Media Types .......................................................................................................................................61 2.8.4 Operation aspects................................................................................................................................62

2.9 LMDS ........................................................................................................................................................63 2.9.1 Overview ............................................................................................................................................63 2.9.2 Technical Aspects...............................................................................................................................64

3 ISSUES TO BE CONSIDERED FOR THE CHOICE OF ACCESS TECHNOLOGY ..................... 68

3.1 Applications and Services ........................................................................................................................68 3.1.1 Services supported within Cable Modem Access Networks...............................................................68

3.2 Network requirement ...............................................................................................................................68

3.3 Network architecture and access network functionality .......................................................................68

4 STANDARDS RELATED TO ACCESS NETWORKS.................................................................... 69

4.1 Standards Bodies ......................................................................................................................................69

4.2 Cable Modem Standards and Specifications..........................................................................................69 4.2.1 The DOCSIS Standard........................................................................................................................69 4.2.2 The DVB/DAVIC EuroModem Standard...........................................................................................72 4.2.3 Security on cable modems ..................................................................................................................73

4.3 Fast Ethernet.............................................................................................................................................73

5 REGULATORY ISSUES................................................................................................................. 75

5.1 Cable Modem Regulatory Aspects ..........................................................................................................75 5.1.1 Cable Open Access.............................................................................................................................75 5.1.2 Cable open access - Business considerations......................................................................................76 5.1.3 Cable open access - Technical Implementation..................................................................................76 5.1.4 Policy-Based Routing .........................................................................................................................77 5.1.5 IP addressing and integration issues ...................................................................................................77

6 MAIN DRIVERS IN THE EVOLUTION OF ACCESS NETWORKS............................................... 78

7 MARKET OVERVIEW..................................................................................................................... 79

7.1 Introduction ..............................................................................................................................................79

7.2 Cable Modem............................................................................................................................................79 7.2.1 Cable Modem Service Costs...............................................................................................................79 7.2.2 Cable Modem Market Stats & Projections .........................................................................................79


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7.3 Fast Ethernet.............................................................................................................................................80

7.3.1 Backbone infrastructure......................................................................................................................80 7.3.2 Network Equipment............................................................................................................................80 7.3.3 End-user infrastructure .......................................................................................................................80

8 EVOLUTION SCENARIOS............................................................................................................. 81

8.1 Introduction ..............................................................................................................................................81

8.2 Cable IP Telephony ..................................................................................................................................81 8.2.1 Introduction ........................................................................................................................................81 8.2.2 Packet Telephony Overview...............................................................................................................81 8.2.3 The DOCSIS 1.1 standard ..................................................................................................................82 8.2.4 PacketCable ........................................................................................................................................82 8.2.5 PacketCable Products .........................................................................................................................83

9 FUTURE POSSIBLE DIRECTIONS ............................................................................................... 85

9.1 Optical Ethernet .......................................................................................................................................85

9.2 LMDS ........................................................................................................................................................85


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1 Introduction The telephony access network has existed for over 100 years from the earliest days of the telephone and has extended its reach to the vast majority of homes and businesses in Europe. Cable TV networks have also existed for many years and, in some parts of Europe, are very widespread. This means that very large legacy networks exist throughout Europe and any consideration of access network roadmap must take this into account. Technologies in common use include: • POTS – the Plain Old Telephony Service. Originally designed for voice, it now carries

voice, fax and internet traffic. • ISDN – the Integrated Services Digital Network. This was the first attempt to optimize the

telecommunications networks for services other than voice and is widespread around Europe.

• Leased lines – which provide a fixed point-to-point connection for users. They come in many forms and in many bandwidths.

• Wireless local loop – which replaces part of the copper network with fixed wireless links. This has advantages in some situations but is not yet universally applicable.

• GSM – Global System for Mobile communications. This is the rapidly expanding digital mobile phone network in Europe. It is good for voice and provides limited data (including internet) capabilities.

• IP – the Internet Protocol. This was intended for Internet communication but is finding wider application. In its present standard form it has limitations, which make it difficult to use for some services, notably voice. Enhancements exist which get around some of these problems such as Intserv, Diffserv and MPLS technologies.

• Asynchronous Transfer Mode. This was the first serious contender for providing broadband multi-service networks and is currently able to handle voice and video better than unenhanced IP can.

New technologies are being introduced into commercial service which allow much more flexible use and provision of high bandwidth in the access network infrastructure. Amongst these are: • ADSL – Asymmetric Digital Subscriber Line - enables a broadband always-on connection

to be provided over a copper pair (typically of 2 Mbit/s downstream and 512 Kbit/s upstream).

• Cable modems - provide a shared broadband interactive link over cable TV networks. This would typically allow a user to have a 2 Mbit/s link.


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• Geostationary satellites and terrestrial broadcasting - can now provide broadband

(asymmetric) interactive capability using the fixed network (e.g. ISDN) for the upstream path.

• Powerline. Some operators have provided services using the electricity distribution network for communications. This has great potential but there are a number of problems to overcome.

• HSCSD and GPRS - are enhancements to GSM to provide a mobile service more suited to data.

• Fixed wireless access – systems, which use radio links to provide connections to customers in fixed locations. It is suitable for broadcast applications as well as broadband telecommunications.

• Passive Optical Networks - provide fiber communications without expensive electronics. They are well suited to enhancing existing networks by replacing the copper between the Local Exchange and a flexibility point. A similar approach can be used with CATV networks, for instance in a Hybrid Fiber Co-ax system.

• IP with Quality of Service differentiation – Differentiated Services, Integrated Services and Multi-Protocol Label Switching are enhancements to IP to handle a range of different services.

New access technologies that are under development are: • UMTS – is the 3 rd generation of mobile systems and will allow data communications at

about 2 Mbit/s. • VDSL – provides very high speed symmetric communication over short copper pairs (or

co-ax cable TV) for the last few hundred meters to the user and is used in conjunction with fiber.

• IPv6 – is an improved form of the Internet Protocol which offers much better addressing and can provide the Quality of Service control needed for services such as voice. It could help to bring about major changes in the way telephony is handled.

• Ethernet and fiber optics – the combination of these two technologies would provide an almost unlimited bandwidth to individual users, but the economics are still not clear.

• Low Earth Orbit satellites and High Altitude Platform Stations – considerably reduce the problems caused by the transmission time to and from geostationary satellites but have not yet been proven commercially viable.

Changes in the regulatory environment are crucial. For instance, the ability for service providers: • To have access to the basic copper network once it is unbundled and to put enhanced

features (e.g. ADSL) on that network will create a major change in the communications environment.


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• New technology takes a long time to completely replace old technology. Users have

invested heavily in devices, which interface to the existing access networks, and it takes years before they can all be persuaded (or can afford) to change to a newer interface. There will be a need to support existing standards for many years. Changes in the access network cannot take place in isolation from other parts of the network. There is no point in providing a super high-bandwidth access network if the capacity of the core network is so limited that it can still only support 64kb/s services. Users have fears about new technology, especially about security issues. It will be important to take those fears into account and allay them.

2 Access Network Solutions 2.1 Access Network Architecture

2.1.1 Star / Multi-star networks The best network topology is star network, guaranteeing point-to-point connectivity and hence providing the full bandwidth the media can support and hence it provides the best QoS and security. However, star network implementation in the access network is very expensive, and inefficient in the usage. The next improved cost effective topology is multi-star technology, which provides some degree of concentration of traffic and making it efficient in its usage. However, the disadvantage is that it brings down the grade of service. The POTS physical access network largely consists of copper pairs, with a dedicated pair (or set of pairs) running from each user’s home or business to the Local Exchange. Flexibility in the allocation of the pairs is provided at a number of “flexibility points” between the user and the Local Exchange. This gives the network more scope to cope with changes in growth patterns than if a continuous cable was run from each user all the way through to the exchange. The distance of users from the exchange can be anywhere between a few hundred meters to tens of kilometers. Star/multistar technology is widely used in the local access telephony network, as shown in the figure below.


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2.1.2 Tree and Branch Networks Tree and branch network is used in cable TV network and is very good for asymmetrical stream of signals.

2.1.3 Bus Networks Most of the data networks are based on the bus topology sharing the capacity of the network among many users. It is simple and cost effective as the users can share the bandwidth on a single bus, however throughput is a function of number of users and type of applications. Typical examples are Ethernet, xDSL etc…

2.1.4 Ring Topology Ring topology is used both in telecom and data networks very effectively. The dual ring topology is common in the transport network (e.g. SDH networks) providing higher reliability in case of failures.

2.1.5 Mesh Networks Mesh networks are important to provide alternate routing in case of traffic congestion and to provide higher reliability. These are used in core networks


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2.2 Technologies addressed

2.2.1 Copper networks POTS access is very widespread in Europe, as in much of the developed world. In western European countries all businesses and most homes have at least one line, and the use of more than one line is becoming more common in many homes, as it has been in businesses for some time. In Eastern Europe, the penetration of the phone service is currently much lower. - ISDN - Integrated Services Digital Network This was the first serious attempt to recognize that telecommunications networks needed to be optimized for services other than voice. It was also an extension of the increasingly digital nature of the core network to the access network. Instead of providing analogue 4 kHz channels, and converting digital data into analogue signals, ISDN is based on 64 kbit/s digital channels. All analogue services, such as voice, are converted into digital signals for transmission over ISDN. This aligns with the way that channels are provided in the core network. ISDN is generally provided over the existing copper access network. ISDN is offered to users in 2 forms: • The basic rate connection, which provides two 64 kbit/s channels plus a signaling channel.

The two 64 kbit/s channels can be combined to provide a 128 kbit/s channel. • The primary rate service, which provides thirty 64 kbit/s channels plus a signaling channel

within a 2 Mbit/s connection. Basic rate connections are the most common and, in effect, give a residential or small business user two high quality connections over their copper pair which can be used for telephony or data. The primary rate connection is more commonly provided to larger users, e.g. for PBX connection, and will usually be provided over a dedicated fiber or radio link. At the time that ISDN was launched, it gave a considerable increase in data transfer rates over the contemporary analogue modems. That advantage is not so pronounced now when current modems at 56 kbit/s are compared with an ISDN channel of 64 kbit/s. However, the ease with which two 64 kbit/s channels can be used together (providing that the users at both ends of the connection can accept this) can still give a significant increase in speed. This has, for instance, made dial-up video services a much more attractive proposition. ISDN has a major advantage over traditional connections in its much reduced call set-up time, as a consequence of the signaling employed. This is of particular benefit for services that need frequent short calls, such as dial-up e-mail.


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In general, the advantages of ISDN over an ordinary phone connection can be summarized as faster call set-up, potentially greater bandwidth, and higher quality. ISDN was first introduced commercially in Europe in the 1980’s, but its rate of adoption has varied greatly from country to country, largely influenced by the varying charge for the service in different countries. Even in western Europe there are significant differences between the degree of use of ISDN in, say, Germany and the UK. As ISDN becomes more ubiquitous, it is being challenged by the arrival of other technologies such as ADSL and cable modems that can provide an even more flexible and bandwidth-rich service for residential users and small businesses. Although European ISDN standards have existed for some years (e.g. Q.931, I.421), major operators first introduced ISDN with their own national or proprietary versions of these standards. These non-standard interfaces are still offered in some countries, mainly to meet the need to connect to older terminal equipment.

• Leased lines Leased lines give to the user a permanent (or semi-permanent) connection between two end-points, for example between a local bank branch and the head office. The major difference between these and other uses of the access network is that no per-call switching is involved once the line reaches the Local Exchange. Leased lines were originally all analogues, as was the rest of the network. They are now becoming largely digitals, in line with the core network. Leased lines vary greatly in their capacity, from a basic permanently wired phone connection between two points to a 155 Mbit/s permanent digital connection. Analogue leased lines are increasingly being used solely for a simple 2-wire or 4-wire permanent connection between two points. Digital leased lines can offer bandwidths from, typically, 2.4 kbit/s upwards and match the PDH or SDH hierarchy at the higher bandwidths (e.g. 2 Mbit/s, 34 Mbit/s, 140 Mbit/s). The use of higher bandwidth leased lines requires the use of dedicated fibers, co-ax cables or microwave links in the access network. Leased lines represent an important market for network operators. For example, BT currently gets about 6% of its revenue from leased lines (i.e. about €1900M per annum). The prices for leased lines vary greatly across Europe, differing by a factor of over 2 for a 30 km line in different countries.


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• ADSL Asymmetric Digital Subscriber Line (or Loop) - ADSL - is a technology, which was first developed about 10 years ago to enable a broadband always-on connection to be provided over a copper pair, whilst maintaining the telephone service for that user. As the name suggests, it is asymmetric and provides a greater downstream capacity (i.e. towards the customer) than the upstream capacity. Because each ADSL customer has a connection to their Local Exchange over a copper pair, there is no sharing of the medium in the access network. This means that the bandwidth available to each customer will not be affected by the number of other customers using the access network at the same time. However, all networks are dimensioned on the basis that not all of the customers will be using their maximum bandwidth all of the time. Thus, at the Local Exchange, the connections into the core (IP) network work on a contention ratio - i.e. the total ADSL bandwidth available in the access network for a group of customers compared to the total core network bandwidth available to that same group. This would typically be 50:1 for residential customers or 20:1 for business customers. The implementation of ADSL can cause practical problems. Because the copper pairs in the cables are being asked to carry much higher bandwidth signals than they were originally designed for, there is a slight danger of interference between pairs in the same cable. This will be more difficult to manage once the local loop is unbundled and several operators are using the same cable. Because access networks have grown over many decades, network operators rarely have good records of the electrical characteristics of each pair. Before ADSL can be provided to a customer, tests have to be carried out on his existing connection and some pair re-arrangement may be needed. ADSL is now being marketed in most major European countries, although the spread within each country is not yet very great and it will take 2 – 3 years before it is generally available. ADSL services being commercially offered in Europe can provide a bandwidth of up to 6 Mbit/s downstream and 512 kbit/s upstream, although a maximum downstream speed of 2 Mbit/s is more common. (In the USA a wider range of 128 kbit/s to around 7 Mbit/s is available). The degree of asymmetry being offered in Europe ranges from 10:1 to 2:1. (In the USA, there are even ratios of 1:1 on offer – these are really DSL rather than ADSL services.) The bandwidth that can be offered depends on the distance of the customer from the Local Exchange, since ADSL is sensitive to the electrical characteristics of the copper network. In a typical European country such as Denmark, it has been estimated that 50 – 60% of the customers could be reached by 2 Mbit/s ADSL whilst 90 – 95% could be reached by lower speed ADSL (e.g. 256 kbit/s downstream). Prices currently being charged in Europe range from €60 per month to €3750 per month. Although there is not a direct correlation between price and bandwidth, because different


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providers have adopted different pricing models, the price generally increases steeply for the higher bandwidth services (i.e. Mbit/s and above).

• VDSL ADSL is already being installed around Europe to provide faster access to the internet for residential and small business users. Typically, it provides 2 Mbit/s downstream and 512 kbit/s upstream. There is likely to be a growing need for speeds which are faster than this and are symmetric, e.g. to support collaborative working between a number of small sites. In theory, a copper cable can carry up to around 50 Mbit/s but it can only do that for short distances – e.g. 300m for 26 Mbit/s. VDSL (Very high speed Digital Subscriber Line) technologies and architectures are being developed to make this possible. These will make use of optical fibers for the majority of the access network from the Local Exchange, with copper pairs (or co-ax cable TV) being used for the last few hundred meters. This is described in more detail in the section on Passive Optical Networks on page 15. The high bandwidth of VDSL and its flexible allocation will also allow different services to be mixed on the same link, e.g. data, video and voice. There are still a number of technical problems to be solved before VDSL becomes a practical solution for widespread application. These are mainly associated with cross talk with other pairs in the same cable and with radio frequency interference.

• Cable modems Cable TV networks were originally co-axial cable networks, although hybrid fiber – co-ax systems are more common in recent networks, and were built to distribute TV and radio broadcasts. Because of this, they were essential one way networks. However, networks have recently begun to be converted to bi-directional working by using part of the available bandwidth for upstream transmission. If there is sufficient bandwidth available in the cable system, then one TV channel can be allocated for carrying downstream data to cable modems and another channel can be allocated for the upstream data. The user is connected to the cable TV network by a cable modem, which is then connected to his PC, and receives an always-on service. Internet protocol will be run over this connection. Cable modem networks are essentially a shared medium so that, for example, a group of users in an area (e.g. 200) would share the available bandwidth. This means that the bandwidth for an individual user can vary considerably in theory but, in practice, is likely to be less variable. The total bandwidth available on the channel will be of the order of 40 Mbit/s. In theory, a single user on the network could use all of this but most network operators restrict the maximum speed available to individual users to, typically, 2 Mbit/s. It is also important to


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realize that the bandwidth is not allocated in fixed size segments to users but that they only seize network resources when they send or receive data, and this tends to be in short bursts. The availability of cable TV systems is very varied throughout Europe, being very widespread in some countries and relatively uncommon in others. Cable TV systems are unlikely to cover areas, which cannot be reached by ADSL, or mainly industrial areas. However, they do give an alternative access network to the copper telephony network with similar standards of reliability and bandwidth. The use of cable modems is very widespread in the USA, being available to about 40 million homes with 3 million cable modem subscribers. The take-up of this service in Europe is currently much lower than in the USA, possibly because of price differences, but the use of cable modems in Europe is expected to grow significantly in the next few years.

• Terrestrial broadcast interaction As with satellites, the terrestrial broadcast network was originally set up to distribute radio and TV programs, mainly to residential sites. Whilst the analogue services were the only ones available, this remained the only use of this network apart from the text pages broadcast by teletext. The introduction of digital broadcast services (DVB and DAB *3) has opened up new opportunities for interactivity. Many broadcasters are now offering services which use the digital terrestrial broadcast system for downstream transmission and use a connection through the telephone network for the upstream connection. There are limitations with this system, such as the need to share the downstream bandwidth between a large number of users. The services, which can be offered are very similar to those provided by satellite. This is a relatively new technology (i.e. interactive digital broadcasting) and its use is therefore in its infancy. We can expect to see more proposals for better use of this medium in the next few years. *3) DVB is digital video broadcast and DAB is digital audio broadcast.

• Powerline The electricity supply network is even more ubiquitous in Europe than the telephone network. The network of cables reaching nearly every building has seemed like an attractive carrier for communications services for some time. However, there are considerable technical, regulatory and commercial obstacles to over come. A major trial was launched by a company (NorWeb) in the UK but, in 1999, the company ceased operations because it could not see a good business case for this technology. However,


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suppliers and operators across Europe and North America still believe that this technology has potential and are carrying out trials – for example in Germany and Finland. They aim to provide a data rate of about 3 Mbit/s to end users in the first commercial realizations of the service. One major advantage of Powerline access over other methods is that the power network extends to most rooms in buildings and it therefore provides the potential for communication within the building as well as to a Local Exchange. The main technical issues that have to be solved involve the frequencies to be used for data transmission. The frequencies needed to allow broadband working are in the same part of the spectrum as the frequencies allocated to police and air traffic control. Power lines are inherently very bad for leaking electromagnetic radiation and the use of these frequencies for broadband transmission could cause serious disturbance to radio services. There are also technical problems to be overcome with the fact that powerlines are an inherently very noisy electrical environment. However, the companies involved in the trials, and the standards organizations, are confident that these problems can be overcome and that it will be possible to introduce commercial services around Europe in 2001.

• Fixed Wireless Access This is a generic term to cover systems, which use radio links to provide connections between customers in fixed locations and telecommunications networks. It covers systems such as LMDS (Local Microwave Distribution System), MVDS (Microwave Video Distribution Systems) and MWS (Multimedia Wireless Systems). They mostly work in the 25 GHz or 40 GHz area of the radio spectrum. These systems are well suited to broadcast and multi-cast applications but also provide broadband data links to and from the customer. Typical figures for a LMDS system would be 36 Mbit/s (shared) downstream and 8 Mbit/s upstream. Compared to a satellite, individual FWA systems have a much smaller coverage area (e.g. a radius of 5 km) and this means that their radio spectrum can be reused many times across a geographical area. For domestic users, IP would normally be used over the system, but ATM connections may be offered to some business users. FWA should provide a similar level of reliability to ADSL systems, but does need line of sight communication. It has the advantage common to most wireless systems of requiring little civil engineering to provide service to a customer once the base station is built. Trials of systems using FWA were carried out under the EU’s ACTS program and licenses have now been issued in many countries for services to start.


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• IP with Quality of Service As described earlier in this paper, IP traffic is rapidly growing. However, a true multi-service network has to be able to carry traffic with a wide range of network requirements – or Quality of Service (QoS) requirements. IP in its current form (IPv4) has very limited capabilities for differentiating between services. A new version of IP (IPv6) is to be introduced which should overcome many of these limitations (see IPv6 on page 17) but there are also other enhancements to IP, which are becoming available sooner to add QoS support. Integrated Services (known as IntServ) allows a client application to request specific performance criteria (e.g. bandwidth) to a particular destination. Every routing point along the path to the destination is then interrogated to check if it has enough bandwidth to meet the requested performance and, in effect, sets up a virtual circuit. A major criticism of IntServ is that this method requires the storage of a large amount of information and so it may not scale well for major networks. Differentiated Services (DiffServ) addresses the scaling problem by combining multiple flows with similar behavior and then dealing only with these combined flows. Packets are assigned to the appropriate combined flow on a per-hop basis. Since the routing nodes only need to maintain information about a relatively small number of combined flows, rather than many paths or virtual circuits, scalability is much improved. The major disadvantage of DiffServ is that it cannot give such an absolute guarantee of QoS as IntServ can, but the statistical probability of an adequate QoS is very high. The other approach which can enhance QoS is multi-protocol label switching (MPLS). MPLS offers a way to create virtual circuits, called "label switched paths", through the otherwise connectionless IP network. This is a useful tool for managing the network, especially in conjunction with IntServ and DiffServ. Technology, which is on the horizon The technology, which we now have, or which is starting to appear, will give a good start in providing a broadband multi-service environment. However, the demands we place on our networks, and the technology needed to meet those demands, do not stand still. Within Europe, the European Commission has an ongoing series of research programs, which look at new communications technologies and their applications. The Advanced Communications Technologies and Services program finished at the end of 1999 and the results of this program can be found at http://www.actsline.org. The current Information Society Technologies program is described at http://www.cordis.lu/ist/overv-1.htm.


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This section highlights just some of the technology, which we can start to see appearing over the next few years. It is not a comprehensive list and it must be borne in mind that many of the advances will be an evolutionary improvement of the existing technology rather than revolutionary technology. We can also expect to see an increasing number of tools appearing to allow us to make better use of the technology, which already exists in the access network.

• IPv6 The protocol, which runs over the access network to allow users to interwork with the Internet, is called the Internet Protocol. In its most common form, it is known as IPv4. This has a number of shortcomings, mainly associated with addressing, security and Quality of Service – for example, IPv4 provides a “best effort” connection, which cannot guarantee adequate QoS for Voice over IP. Extensions to IPv4 exist to partially tackle these problems, as do some proprietary solutions, but the longer-term solution is a new version of the internet protocol, known as IPv6. IPv6 provides a much better structured, more flexible and larger addressing system than IPv4. This should allow better management of routing through the backbone network of the internet. IPv6 also has enhanced security. For example, it is inherently able to supply information that will enable the source of a message to be checked, something which is not always easy with IPv4. For many service providers, the most interesting feature of IPv6 is likely to be its ability to convey information across the network about the type of traffic it is carrying. This will enable the Internet to treat voice (which can only tolerate delays of a few milliseconds) in a different way to e-mails (which can tolerate delays of several minutes) and make voice and video communication a more attractive reality.

• Ethernet and fiber optics DSL has inherent problems with cross talk and with radiation, and with the testing of the copper network needed to find a copper pair with acceptable electrical behavior. Cable TV does not suffer from these problems, but does suffer from the need to share the available bandwidth between a number of households. It is possible that DSL and cable modems may be superseded by a combination of Ethernet and fiber optics in the future. Ethernet is a well-established computer networking technology, which is widely used to connect computers in offices. Ethernet networks can have links of up to about 50 km and have been shown, in trials, to be capable of working at 10 000 Mbit/s – although speeds of 10 Mbit/s or 100 Mbit/s or more commonly used.


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Fiber optic cables can carry a vast amount of traffic in a small physical space. For instance, a single fiber can easily carry 10 Gbit/s *4) and a single cable can contain 1000 fibers. Installing a fiber to every home or business, and running fast Ethernet over these would eliminate the potential bottlenecks in the access network eliminated for the foreseeable future. There is still debate about the economics of doing this, and whether such a high bandwidth is needed at present, but the viability of this approach is increasing as costs fall and demand for bandwidth increases. It is also being made more attractive in those countries where the incumbent network operator must allow competitors to install cable in their right of way. This can drastically reduce cable installation costs, which make up the bulk of the costs in cable-based access networks. *4) 10 Gbit/s = 10 Giga bit/s = 10 000 000 000 bit/s

• Low earth orbit (LEO) satellites Communications satellites have until recently been mainly geostationary, i.e. they appear to hover above a fixed point on the earth. This has the major advantage that the antenna used to connect the ground station to the satellite does not have to track the path of the satellite across the sky and calls do not have to be handed over from one satellite to the next as the first satellite flies below the horizon. The major disadvantage of a geostationary satellite is that it has to be at around 36 000 km above the earth. This means that the signal being received from the satellite is not very strong (and that any transmitter from the ground to the satellite has to provide a strong signal) and that the transmission time to and from the satellite is high. Anybody who has made a phone call via a satellite will be aware of the slightly disconcerting effects of this. This delay can also affect protocols which assume failure if they don’t receive a rapid response.

Figure 3: Geostationary & LEO satellites


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One solution is to provide satellites in a much lower orbit of around 1 000 km (See Figure 3). These have the advantage of a much lower delay and the reduced power needed means it is much easier to design aerials for bi-directional communication. By using LEO satellites it is possible to provide users with a high bandwidth for download and upload. The main disadvantage of LEO systems is that a large number of satellites (between 50 and 300) are needed for good coverage of the world. Recent years have seen several schemes launched to provide LEO services for voice or multi-service broadband communication. A number of these have been commercially unsuccessful and this looks like a technology that might be ahead of the market need.

• High Altitude Platform Stations LEO satellites have the disadvantage that they move relative to the earth. This means that they will spend a percentage of their time over parts of the earth’s surface where there is little demand for them and, conversely, a large number of satellites is needed to provide constant service to any one location. An alternative approach, which is being considered, is High Altitude Platform Stations. There are a number of variations of these being proposed, but a typical scheme is proposing a balloon-based platform about the size of a football field at a height of 21 km. They plan to launch these over large cities starting in 2002. These would offer broadband communication similar to that which is possible from satellite, with simpler aerial design and transmission times similar to the terrestrial network. The main problems that have to be resolved for HAPS are with the physical platform rather than with the communications equipment. Problems and opportunities with access network evolution The preceding sections have described some of the many technologies, which are available, or are becoming available, for access networks. The end user rarely cares about the technology that they are supported by. All they want is to be able to use a wide range of services in the easiest, safest and cheapest way possible. However, that often means that the service provider has to be able to take advantage of any improvements in access network technology as rapidly and cheaply as possible. One characteristic of the access network is that it has almost universal coverage of Europe. To achieve that has required a great deal of investment of time and capital, and any far-reaching changes to the network could also require a major investment in time and capital. As a consequence of that, any change to the infrastructure must be on an evolutionary path which is not a “dead end” but which really does lead to the future.


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There are a number of trends that can be seen in the evolution of the access network over the next ten years.

The first one is the continued high growth in demand for internet-based services. For the next few years at least, this is expected to continue to grow at the same high rate as it has done recently. Many users will become increasingly unhappy with the slow response times that are achieved using analogue modems over telephone lines and will demand something better. For most residential and small business users, that is likely to be provided by ADSL or cable modems. However, there will still be users who are perfectly happy with the service provided by 64 or 128 kbit/s ISDN, or even 56 kbit/s analogue, and will not abandon this technology. One of the main factors affecting the spread of ADSL and cable modems will be pricing. Most telephone companies still apply usage-based charges to Internet access via POTS or ISDN (e.g. €0.05 per minute), whereas cable modems and ADSL are charged on a flat fee (monthly service charge) basis. For a heavy user, that makes those technologies much more attractive. The usage-based charges are likely to be abandoned by many telephone companies in the near future and it will be much easier for users to decide if the cost of ADSL (or cable modems) is justified by their extra benefits in terms of bandwidth and always-on connectivity. An alternative view of evolution for Internet access is that many residential customers will not want to buy PCs, especially in poorer communities, but will still willingly pay for TVs. In that view of the future, interactive services via TV will become more important, including the provision of e-mail and e-commerce services. The evolution of the satellite, cable and terrestrial broadcast access networks will play a key role in taking the information society to all sectors of Europe. The ability of these networks to interwork with telecommunications networks (for the return path) will be crucial, at least in the early stages. The Internet will start to take over part of the role of the traditional telephony network as we see improved Quality of Service control in the Internet leading to increasing use of Voice over IP. This will lead to access networks becoming true multi-service networks. However, the POTS network will still exist for many years as the number of users who do not have, or need, Internet access remain significant. There will be increasing diversity in the technology used for access networks. Until recent years, the choice was largely between copper cable for telecommunications and radio, satellite or co-ax cable for broadcasting. Now, anybody wanting to set up or extend an access network for telecommunications or broadcasting has a choice of copper cable *5) , fiber, radio, co-ax cable, satellite or combinations of these. Some of these technologies (e.g. wireless local loop) require relatively little capital investment and are quick to install, thus being especially suited to new entrant operators trying to gain a foothold in the market. The increasing pace of change means that there will be overlap between the roll-out of new technologies. As an example, in the UK, BT only started to aggressively market


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ISDN to domestic and small business users about a year ago. It is now starting to market ADSL, which is targeted on much the same market segment. That isn’t an ideal strategy from the point of view of BT, but it is driven by pressure from its competitors and from the UK telecommunications regulator. Mobility will be increasingly important for users. The growth in mobile phones has already outstripped the growth in fixed communications and is likely to continue to do so over the next few years. Mobile phones and networks are also becoming more capable and can already offer basic information services and e-mails over the Internet. With the advent of GPRS and, later, UMTS they will become much better at handling data-based traffic, such as internet access. However, the radio spectrum available is always going to be much more limited than the bandwidth that is available over land lines. This means that the fixed network is always going to be able to provide much higher bandwidth service than mobile networks. The majority of users will also still do their daily work in one fixed location and will spend much of their leisure time at fixed locations. For those reasons, the fixed network will still be the major provider of broadband multi-service facilities. However, we may well see mobile voice telephony become more important than voice telephony over the fixed network.

*5) For broadcasting, this is really only suitable for low quality web-casts. These trends provide plenty of opportunities for wise service and network providers to take advantage of the new technologies to offer innovative and useful products to their customers. However, they must also be aware of the factors that will influence evolution which are not simply related to the capabilities of technology.

Changes in the regulatory environment are crucial. The unbundling of the local loop is being actively planned throughout Europe. The ability for service providers to have access to the basic copper network and put enhanced features (e.g. ADSL) on that network will create a major change in the communications environment. New technology takes a long time to completely replace old technology. Users have invested heavily in devices, which interface to the existing access networks, and it takes years before they can all be persuaded (or can afford) to change to a newer interface. There will be a need to support existing standards for many years. Changes in the access network cannot take place in isolation from other parts of the network. There is no point in providing a super high-bandwidth access network if the capacity of the core network is so limited that it can still only dawdle along at 64 kbit/s. Synchronizing the capabilities of the various networks is more of a challenge in the environment of increasingly fragmented network ownership. Users have fears about new technology, especially about security issues. There is a natural fear that a shared medium such as cable or wireless is less secure than a dedicated pair of wires. It will be important to take those fears into account and allay them.


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Conclusions Those of us who have to deal with access networks are living in interesting times. We are seeing far more opportunities for major change than have ever been possible before. We are seeing far more convergence of previously disparate services than has ever been seen before. And we are seeing far more uncertainty about evolution paths than has ever been seen before. For those that get their evolution strategy right, they will be rewarded with the ability to deliver services that will keep their customers happy, even as they become increasingly demanding. One way to get the right strategy would be to buy a crystal ball and take lessons in fortune telling. A more successful strategy is to make sure that any changes in the network retain as much flexibility as possible for future enhancement.

2.3 Technologies to be addressed

2.3.1 Copper networks - Traditional telecom networks: PSTN, ISDN, leased lines - Ethernet

o 10Mb Ethernet o 100VG Any LAN o Fast o Gigabit

2.3.1.1 XDSL Although there is some availability of broadband access today, it is mostly limited to companies or to people who are fortunate enough to live in residential areas where broadband has been brought into the neighborhood. Nonetheless, these represent a vast minority of the people interested in getting broadband access. Therefore, numerous companies are concentrating their energies on (channeling their efforts towards) providing widely available broadband access through a number of different technologies at an affordable price for customers. One of such technology is xDSL technology, which in different forms to fulfill users requirement. These being: ADSL, RADSL, VDSL, HDSL and SDSL. xDSL technology now provides multiple forms of data, voice, and video to be carried over twisted-pair copper wire on the local loop between a network service provider's (NSP's) central office (CO) and the customer site. Because xDSL uses new signal processing techniques it is able to leverage the existing local loop infrastructure in order to increase the amount of data transmitted over analog lines. This has led it to be touted as one of the most viable options to alleviate the problems of limited bandwidth. Since it requires minimal investment on the carrier's side, carriers could potentially introduce xDSL services to its customers faster and more cost-effectively than other options


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Customers interested in xDSL services can choose from a number of DSL transmission technologies. The table below summarizes each technology based on: mode, maximum baud rate, maximum distance the technology can travel over twisted-pair wires, and the types of applications each technology is best suited for. The table also illustrates the fundamental trade-off of DSL technology - baud rate decreases as the maximum distance increases from the customer's site to the CO.

Technology Mode* Maximum baud rate

Maximum distance over 24 gauge LTP

Application

ADSL/RADSL Asymmetric Downstream 1.5 to 9Mbps; Upstream 16 to 640kbps

1800 m(1200 m for speeds above 1.5Mbps)

Internet/intranet access, video on demand, database access, remote LAN access, interactive multimedia, lifeline phone service

HDSL Duplex T1 up to 1.544Mbps; E1 up to 2.048Mbps 1500 m Replace local repeatered T1/E1 trunk,

PBX interconnection

SDSL Duplex T1 up to 1.544Mbps; E1 up to 2.048Mbps 1000 m

Same as HDSL plus premises access for symmetric services like video conferencing

VDSL Asymmetric Downstream 13 to 52Mbps; Upstream 1.5 to 2.3 Mbps

1000 to 450 m Same as ADSL plus HDTV

ADSL = Asymmetric Digital Subscriber Line , RADSL = Rate-Adaptive Digital Subscriber Line , SDSL = Single-pair Digital Subscriber Line VDSL = Very high bit-rate Digital Subscriber Line

2.3.1.2 Benefits

• Uses new signal processing techniques to leverage existing local loop infrastructure in order to get more on and off analog lines.

• ADSL users can use a single twisted pair for both data and voice communications.

• Carrier powered over copper wire. Therefore xDSL users will still be able to receive service even in the event of a power failure.

2.3.1.3 Drawbacks

• No interoperability due to lack of standards among component manufacturers and carriers.

• Cross-talk interference from nearby wires.


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• Need to lower power system requirements from the present 8 to 12 watts down to 2 to 3 to abide by federal regulations.

• Tradeoff between length of lines, data speeds, and differences in upstream and downstream traffic.

2.3.1.4 Costs ADSL is being introduced be all European operators with broadband internet service provision. The cost of an ADSL modem is in the hundreds of Euros . For a SOHO (small office, home office) user ADSL is the ideal choice compared to ISDN or T1 options depending on the SOHO's proximity to the CO and whether his/her carrier offers ADSL as an alternative. This is why carriers have initially targeted ADSL services to the SOHO user rather than the average consumer. With time, the economies of scale could lower the entrance cost, making it a feasible alternative for the average consumer. The true costs to carriers depend on regulatory issues dealing with the need to unbundled xDSL service and how costs are to be allocated between network provider and outside competitors.

2.3.2 Wireless networks - Satellite

o VSAT o HMDS o LEO

- Fixed Wireless o LMDS

- Wireless LAN o 802.11a o 802.11b o Bluetooth

- Mobile Networks o GPRS o UMTS o IMT2000

- Digital TV Data - Flying Broadband - Mobile ad-hoc network (manet)

2.3.3 Fiber Optic Networks The creation of national fiber optic networks for access to the backbone is viewed as a very costly but also as a very necessary and inevitable outcome. Cable modems, xDSL and wireless access are excellent, much lower initial capital investment alternatives to fiber optic networks.


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A combination of these technologies may satisfy the need for broadband access until enough companies pursue investment in private national fiber optic networks. AT present the backbone optical fiber networks have the capacity of 622Mb/s to 2.5 Gb/s. The WDM technologies are taking this range to reach up to 40Gb/s. Fiber optic connections to the home are not expected to grow in this range and the spread of cable modems, xDSL and wireless communications, will provide transition scenarios towards the futuristic fiber optic access networks. Fiber optic access networks are used by corporate networks in the form of leased lines, or extension of SDH systems, into their premises. The passive optical networks (PONs), coaxial-coaxial systems and coaxial to the home system concepts have been demonstrated by many laboratories, the real deployment of these technologies so far has not lead to any success story, so far.

2.3.3.1 Technical Fundamentals The traffic growth due to explosion of internet/web and mobile applications among all type of users led to the need of introducing optical fibers in the backbone on priority and in access network in few cases. The competition to achieve higher and more cost-effective fiber-optic capacity is intense. Wave division multiplexing (WDM) an dynamic WDM technologies are maturing and are ready for commercial deployment. Companies already offering various forms of transmission enhancements include Lucent, Alcatel Alsthom Group; Northern Telecom Inc.; NEC Corp.; Pirelli SpA, and Siemens AG etc The backbone is composed of high-speed fiber-optic cables, which shuttle information through the Internet at 45 Mb/s to 2.5 Gb/s

2.3.3.2 Benefits/Drawbacks

• With the increased deployment of fiber optic network in the backbone, transmission capacity tariffs have plummeted, which promotes the usage of high bandwidth application.

• The extension of the optical network to the home is a desirable feature but still expensive for the network provider and would be expensive to the users as well. The type of applications generally used by the customers can be easily supported by copper networks

• Reliability and Quality of transmission is very high due to non-interference problems like in copper networks.

• Not easily scalable because the investment required to install additional fiber optic lines is significant. This problem is largely mitigated however by the potential capacity of just one fiber optic strand.


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2.3.3.3 Cost Optical coaxial backbone network is an infrastructure to be exploited by the incumbent and network providers and service providers equally. With the introduction of WDM and DWDM technologies, the available bandwidth is getting multiplied and hence reducing transmission costs. The usage of high-band with services is promoted to get best of backbone network.

2.4 UMTS / IMT-2000

2.4.1 What is UMTS (IMT-2000) ? UMTS is one of the major new third generation (3G) mobile systems being developed within the framework which has been defined by the International Telecommunications Union (ITU) and known as IMT-2000 (International Mobile Telecommunications). UMTS will play a key role in creating the future mass market for high-quality wireless multimedia communications that will approach 2 billion users worldwide by the year 2010. UMTS has the support of several hundred network operators, manufacturers and equipment vendors worldwide. UMTS has the support of many major telecommunications operators and manufacturers because it represents a unique opportunity to create a mass market for highly personalized and user friendly mobile access to the information society. UMTS seeks to build on and extend the capability of today’s mobile, cordless and satellite technologies by providing increased capacity, data capability and a far greater range of services using an innovative radio access scheme and an enhanced, evolving core network. UMTS will enable tomorrow’s wireless information society, delivering high-value broadband information, commerce and entertainment services to mobile users via fixed, wireless and satellite networks. It will speed convergence between telecommunications, information technology, media and content industries to deliver new services and create fresh revenue-generating opportunities. UMTS is being standardized by the European Telecommunications Standards Institute (ETSI) in the IMT-2000 framework, in co-operation with other regional and national standardization bodies around the world to produce the detailed standards to satisfy growing market needs for global roaming and service availability. IMT-2000 has been defined by the ITU as an open international standard for a high capacity, high data rate mobile telecommunications system incorporating both terrestrial radio and satellite components. UMTS is an important part of wider initiatives to satisfy the needs of corporate users and the mass market. Complementary work is under way throughout ETSI and other fora on every aspect of the emerging information society, multimedia, information and content.


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The key difference between this system and previous mobile (wireless) systems, such as GSM is that the earlier systems were conceptually separate from the fixed (wire line) telephone network. The goal of this system is to integrate wire line and wireless systems to provide a universal communications service, such that a user can move from place to place while maintaining access to the sum set of services (see figure 1).

(GSM: Groupe Spéciale Mobile or Global System for Mobile communications; FLPTMS: Future Public Land Mobile Telecommunication System

WAND: Wireless ATM Network Demonstrator, MBS SAMBA: Mobile Broadband System - System for Advanced Mobile Broadband Applications;

ISDN: Integrated Services Digital Network; B-ISDN: Broadband ISDN; DECT: Digital European Cordless Telecommunications; PHS: Personal - Handyphone System;

MEDIAN: Wireless Broadband CPN/LAN for Professional and Residential Multimedia Applications)

Figure 1. UMTS vs other communication standards (from http://www.imst.de/mobile/median/median.html)

2.4.2 Benefits offered by UMTS Ease of use and low costs. Wireless customers want useful services, easy-to-use terminals and good value for money, UMTS is envisioned to offer services that take into account these requirements. The main user types of UMTS are shown on figure 2.


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Figure 2. Main user types of UMTS - (from www.imt-2000-online.com) New and better services. Market studies show that voice will remain the dominant service for existing fixed and mobile telephone networks, including GSM, through 2005. Users will demand low-cost, high-quality voice service from UMTS. However, the opportunity for increased revenues through UMTS comes from offering advanced data and information services. Long term, industry forecasts for UMTS show a strongly growing multimedia subscriber base by the year 2010. Six service categories that represent the major areas of demand for 3G-enabled services over the next 10 years can be defined, as follows: customized infotainment, multimedia messaging service, mobile intranet/extranet access, mobile Internet access, location-based services and rich voice (simple and enhanced voice). Almost of these types of applications require the guarantee of quality of service (particularly guarantee of delay, jitter and packet loss rate). UMTS allows a user to negotiate QoS characteristics that are the most appropriate for carrying information. In UMTS, four traffic classes have been identified : conversational, streaming, interactive and background classes. The characteristics of these classes are summarized in table 1.

2.4.2.1.1.1.1 Traffic

class 2.4.2.1.1.1.1.1 Characteristics 2.4.2.1.1.1.2 Example of

applications Preserve time relation (variation) Voice, videotelephony,


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Conversational between information entities of the stream, stringent and low delay

video games

Streaming

Preserve time relation (variation) between information entities of the stream.

Streaming multimedia (video clips, lectures)

Interactive Request response time Preserve data integrity

Web browsing, network games, database retrieval

Background

Destination is not expecting the data within a certain time, Preserve data integrity

File downloading, emails.

Table 1. UMTS QoS classes High bit rates. One factor, which clearly sets UMTS above the second-generation mobile systems, is its potential to support 2 Mb/s data rates for users from the outset. This capability, together with inherent Internet Protocol (IP) support of UMTS, is a powerful combination to deliver interactive multimedia services as well as other new wideband applications such as video telephony and video conferencing. As the demand for user data rates increases in the long term, UMTS will be developed to support even higher data rates. In later phases of UMTS development, there will be a convergence with even higher data rate systems using mobile wireless Local Area Network (LAN) technologies (microwave or infrared) providing data rates of for example 155 Mb/s in indoor environments. Bit rate on demand. UMTS is also being designed to offer data rate on demand, where the network reacts flexibly to a user’s demands based upon his/her profile and the current status of the network. Simply put, there should be no worries about how and when to connect to the network. Common access interface. UMTS services are based on standardized service capabilities, which are common throughout all UMTS user and radio environments. This means that a user will experience a consistent set of services even when he/she roams from his/her home network to other UMTS operators. Users will find the same interface, whether they are in their home network or roaming. The Virtual Home Environment (VHE) will ensure the delivery of the service provider’s total environment, including for example, a corporate user’s virtual work environment, independent of the user’s location or mode of access (satellite or terrestrial). VHE will also enable terminals to negotiate functionality with the visited network, possibly even downloading software so that it will provide "home-like" service. The ultimate goal is that all networks, signaling, connection, registration and any other technology should be transparent to the user so that mobile multimedia services are simple, user friendly and effective.

2.4.2.2 Mobility and Coverage UMTS has been designed from the outset as a global system, comprising both terrestrial and global satellite components. Multi-mode terminals that are able to also operate via second generation systems such as GSM 900 and 1800 will further extend the reach of many UMTS services. A subscriber will be able to roam from a private network, into a picocellular/microcellular public network, then into a wide area macrocellular network and then to a satellite mobile network with minimal break in communication.


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2.4.2.3 Radio technology for all environments The UMTS radio access system, UTRA (UMTS Terrestrial Radio Access), will support operation with high spectral efficiency and service quality in all the physical environments in which wireless and mobile communication take place.

2.4.3 UMTS deployment UMTS has been launched in Japan in 2001 (start of the DoCoMo system; see http://www.nttdocomo.co.jp/english/index.shtml) and it is expected, in Europe, for 2002. UMTS licenses have already been awarded in several European countries. The UMTS community has chosen aggressive timescales for the introduction of UMTS in order to meet the demands of customers in the early 21st century. The introduction of UMTS relies on many elements being in place including, for example, technology development, standardization, and Applications Programming Interfaces (APIs) to a service creation environment, regulation, licensing and spectrum allocation. To meet this 2002 deadline, UMTS is following a phased approach allowing its capabilities to be improved over time following its introduction. At launch, terrestrial UMTS will have the capability for data rates up to 2 Mb/s, but it is designed as an open system which can evolve later on to incorporate new technologies as they become available. This will allow UMTS to eventually increase its capability above that currently being standardized, much in the same way that GSM will evolve from the original capability of 9.6 Kb/s for data to GPRS (up to 115 Kb/s) and then to EDGE (Enhanced Data Rates for GSM Evolution) technology (384 Kb/s). UMTS is a substantial advance over existing mobile communications systems. It is being designed with flexibility in mind above all else - for users, network operators and service developers and embodies many new and different concepts and technologies. By 2010, 28% of the world’s 2.25 billion mobile cellular subscribers will be 3G subscribers. This is a conservative estimate, taking into account slower network build-out and service commercialization in emerging and developing economies. Taking a conservative analysis approach, forecasts predict that total service provider-retained revenues for 3G services in 2010 will reach US$322 billion. Of those revenues, 66% will come from 3G-enabled data services. The cumulative revenue potential for mobile services providers between now and 2010 is over one trillion US dollars. The consumer segment will contribute about 65% – a true mass-market success.


http://www.nttdocomo.co.jp/english/index.shtml

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2.4.4 UMTS access

2.4.4.1 Spectrum allocation The process of reserving and allocating frequency spectrum for the deployment of new radio systems takes many years. As far back as 1992, the World Administrative Radio Conference (WARC) allocated the frequency spectrum for the implementation of a single-wide 3G mobile system from the year 2000. Within Europe, the European Radiocommunications Committee (ERC) of the CEPT (European conference on Postal and Telecommunication administrations) is responsible for the actual allocation of radio frequencies. ERC specifies that 155 MHz of spectrum shall be reserved for the terrestrial component of 3G systems. The 155 MHz is split into paired band 2*60 MHz (1920-1980 MHz and 2110-2170 MHz bands) for frequency division duplex (FDD) and unpaired bands separate 20 MHz and 15 MHz (900-1920 MHz and 2010-2025 MHz bands) for time division duplex (TDD). FDD systems use different frequency bands for uplink (from the subscriber to the network) and downlink (from the network to the subscriber) separated by the duplex distance, while TDD systems utilize the same frequency for both uplink and downlink. See figure 3.

GSM 1800/Downlink

PHS

PCS/Uplink

Europe

Japan

1800 MHz 1850 MHz 1900 MHz 1950 MHz 2000 MHz 2050 MHz 2200 MHz2150 MHz2100 MHz

USA

PCS/Downlink

IMT-2000Uplink

IMT-2000Downlink

IMT-2000 MSS Downlink Downlink

IMT-2000 IMT-2000 MSS IMT-2000 DECT TDD Uplink Uplink TDD

(DECT: Digital European Cordless Telecommunications; PCS: Personal Cellular System; MSS: Mobile Satellite Service) Figure 3. Spectrum allocation


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2.4.4.2 Standardization and harmonization In december 1998, a body called the 3rd Generation Partnership Project (3GPP) was established with the aim of harmonizing the various proposals (based on W-CDMA) submitted by various countries or regions for the multiple access schemes to be employed on the air interface. It was founded by the following regional standardization bodies : ARIB (Japan), TTC (Japan), ETSI (Europe), T1 (US), TTA (Korea), and joined later by CWTS (China). Subsequent to the establishment of 3GPP, a second body, 3GPP2, was established around cdma2000 proposal. In June 1999, a group of international operators, the Operator Harmonization Group (OHG), proposed the harmonization of 3GPP and 3GPP2 concepts, to be known as Global Third Generation (G3G), in order to allow interoperability between UTRA and cdma2000. The proposals of OHG were accepted by both 3GPP and 3GPP2 to produce a standard with the following three modes of operation : - CDMA-DS (Code Division Multiple Access – Direct Sequence), based on UTRA FDD - CDMA-TDD, based on UTRA TDD. - CDMA-MC (CDMA Multi Carrier) based on cdma2000. In november 1999, five models have been adopted by ITU as IMT-2000 standards: - IMT-MC (multicarrier) : standard cdma2000 - IMT-SC (single carrier) : standard UWC-136 - IMT-DS (direct sequence) : standard UTRA FDD - IMT-TC (TDMA/CDMA) : standards UTRA TDD, TD-SCDMA - IMT-FT (FDMA/TDMA) : standard DECT.

2.4.4.3 Radio access network: the UTRAN architecture UTRAN (or UMTS Terrestrial Radio Access Network) has been defined as an access network. This means that the radio interface independent functions are outside the scope of UTRAN specifications and handled by the core network. The UTRAN consists of one or more radio network subsystems (RNSs), which in turn consist of base stations (called Node Bs) and radio network controllers (RNCs). (see figures 4 and 5). A node B may serve one or multiple cells. Mobile stations are termed user equipments (UEs) and they are likely to be multimode to enable handover between FDD and TDD modes, and GSM as well. The main function of the Node B is to perform the air interface L1 processing (channel coding and interleaving, rate adaptation, spreading, etc.). It also performs some basic radio resource management operation as the inner loop power control. It corresponds to the GSM base station.


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The UE consists of two parts: the mobile equipment (ME) used for radio communication over the Uu interface, and the UMTS subscriber identity module (USIM) which is a smart card that holds subscriber identity and performs authentication algorithms and stores authentication and encryption keys.

Figure 4 . Radio access architecture. From WWW.ericsson.com


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Iur

Uu

UE RNC

RNS

UE: User EquipmentRNC: Radio Network ControllerRNS: Radio Network SubsystemUu: Radio interfaceIub: Interface between Node B and RNCIu: Interface between UTRAN and core networkIur: Interface for handover between RNCs

CoreNetwork

Iub Iu

Node B

Uu

UE RNC

RNS

Iub Iu

Node B

InternetISDN

External networks

Figure 5. UTRAN system architecture The protocols within UTRAN include (figure 6): - Node B Application Protocol (NBAP) : it is responsible for the allocation and control of

radio resources to Node Bs. - Radio Network Subsystem Application Protocol (RNSAP) : it is responsible for co-

ordination of radio resource between Node Bs in neighboring RNCs (i.e., in support of links during soft-handover)

- Radio Access Network Application Protocol (RANAP) : it is used to support signaling across Iu interface. In particular, it supports the transfer of layer 3 messages between the UE and the core network. It is also used during establishment of layer 3 connections between the UTRA and the core network.


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Iu

Iu

Iur

Iu

Iub

RANAP

RNSAP

NBAP

RRC

RNC

NBAP

Node B

RRC

UE

RANAP

Corenetwork

RANAP

RNSAP

NBAP

RRC

RNC

Figure 6. Resource control signaling protocols The standardization of UTRA is scheduled to progress by 3GPP on the basis of annual releases. 3GPP release 99 specifies an ATM implementation on the Iub interface but it is likely that in next releases a migration to IP will be adopted. Figure 7 shows a simplified version of the protocols running between a UE and the UTRAN. The transport channels carry control plane or user plane data between the UE and RNC, mapping onto physical channels on the air (Uu) interface allocated to the radio resource control (RRC) and ATM AAL2 connections over Iub interface. The medium access control (MAC) layer and radio link control (RLC) reside in the RNC. The frame protocol (FP) s responsible for the relaying of transport channels between UE and RNC via the node B. This protocol stack is common to both FDD and TDD modes with some minor differences.


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IubUu

RRC

Controlplane

Userplane

RLC

MAC

Physical layer Physical layer Physical layer Physical layer

UE Node B RNC

ATM

AAL2

ATM

AAL2

FPFP

MAC

RLC

RRC

Userplane

Controlplane

Figure 7. Protocol diagram

2.4.4.4 Core network The core network is responsible for switching and routing calls and data connections to external networks (see figure 8). It comprises transport 'pipes' for information flow, nodes that route traffic and nodes that provide call control intelligence. There are three basic solutions for the core network to which WCDMA radio access networks can be connected (see figure 9). The basis of the second generation systems has been either the GSM core network or one based on IS-41. Both will naturally be important options in 3G

systems. An alternative is GPRS (General Packet Radio Service, it is a GSM phase 2+) with an all-IP-based core network. The most typical connections between the core networks and the air interfaces are shown by the following figure. Other connections are expected to appear in the future. It is expected that the operators will remain with their second generation core network for voice services and will then add packet data functionalities on top of that. Later, it will be possible to use IP-based core networks for all services.


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Figure 8. Mobile communication system infrastructure

from www.ericsson.com

Inter-workingfunctions

GSM corenetwork

IS-41 corenetwork

GPRS IP corenetwork

TDD ModeTD-CDMA

EDGE

cdma2000multicarrier

WCDMA

Figure 9. Core network relation to 3rd generation air interface alternatives

2.4.4.5 Radio interface protocols The radio interface protocols are needed to set up, reconfigure and release radio bearer services (including the UTRA FDD/TDD service).


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In the UTRA FDD radio interface, the layer 2 (i.e., data link layer) is split into sublayers (see figure 10). In the control plane, layer 2, contains two sublayers: Medium Access Control (MAC) and Radio Link Control (RLC). In the user plane, in addition to MAC and RLC sublayers, two additional service-dependent protocols exist: Packet Data Convergence Protocol (PDCP) and Broadcast/Multicast Control protocol (BMC). Layer 3 (i.e., network layer) consists of one protocol, Radio Resource Control (RRC), which belongs to the control plane. The PDCP, which exists only in the user-plane, contains compression methods that are needed to get better spectral efficiency for services requiring IP packets to be transmitted. The BMC, which exists only in the user-plane, is designed to adapt broadcast and multicast services on the radio interface.

Layer 1

Layer 2

Layer 3

SignallingRadio bearers

User- planeRadio bearers

Transport channels

Logical channels

PHY

RLC

RRC

BMCPDCP

MAC

Control-plane User- plane

Figure 10. UTRA FDD Radio interface protocol architecture

The overall radio interface protocol architecture is shown in figure 10: - The physical layer offers service to MAC layer via transport channels which are

characterized by how and with what characteristics data is transferred. - The MAC layer offers services to RLC by means of logical channels that are characterized

by what type of data is transmitted. In the MAC layer, the logical channels are mapped onto transport channels. The MAC layer is also responsible for selecting an appropriate


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transport format for each transport channel according to the instantaneous source rate of the logical channels. Other functions of MAC layer are: priority handling between data flows of one UE, priority handling between UEs by means of dynamic scheduling, identification of User Equipments, multiplexing/demultiplexing of higer protocol data units, traffic volume monitoring, ciphering, transport channel type switching.

- The RLC offers services to higher layers which describe how RLC handles the data packets. RLC protocol can operate in three modes: transparent, unacknowledged, and acknowledged mode. In transparent mode, no overhead is added to higher layers, erroneous protocol data units can be discarded of marked erroneous. In the unacknowledged mode, no retransmission protocol is in use and data delivery is not guaranteed. In the acknowledged mode, an automatic repeat request mechanisms is used for error correction. The main functions of RLC layer are: segmentation and reassemble of variable-length PDUs of higher layers, padding, transfer of user data, error correction, protocol error detection and correction, in-sequence delivery of higher layer PDUs, duplicate detection, flow control, sequence number check, ciphering, suspend/resume of data transfer.

- The RRC layer offers services to higher layers (to the non access stratum) used by the User Equipment side and by RANAP protocol in the UTRAN side. RRC messages carry all parameters required to setup, modify and release layer 2 and layer 2 protocols entities. RRC messages carry all higher layer signaling and the mobility of user equipment in the connected mode is controlled by RRC signaling (measurements, handovers, cell updates, etc.). The RRC has a long list of functions to perform: broadcast of system information, paging, establishment, maintenance and release of RRC connections between UEs and UTRAN, control of radio bearers, control of security functions, integrity protection of signaling messages, UE measurement reporting and its control, RRC connection mobility functions, open loop power control, cell broadcast related functions, …

The data transfer services of the MAC layer are provided on logical channel. Each logical channel is defined by the type of information transferred. There are control channels and traffic channels:

- Broadcast Control Channel (BCCH): a downlink channel for broadcasting system control information,

- Paging Control Channel (PCCH): a downlink channel that transfers paging information,

- Dedicated Control Channel (DCCH): that transmits dedicated control information between UEs and the network.

- Common Control Channel (CCCH): for transmitting control information between UEs and the network.


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- Dedicated Traffic Channel (DTCH): a point-to-point channel dedicated to

one UE for transfer of user information.

- Common Traffic Channel (CTCH): a point-to multipoint unidirectional channel for transfer of user information for all a group of UEs.

The control interfaces between RRC and all the low layer protocols are used by the RRC layer to configure characteristics of the lower layer protocol entities, including parameters for the physical, transport and logical channels.

2.4.4.6 WCDMA in 3rd generation systems In the standardization fora, particularly 3GPP, WCDMA (Wideband Code Division Multiplexing Access) technology has emerged as the most widely adopted 3rd generation air interface. Within 3GPP, WCDMA is called UTRA FDD and UTRA TDD. In CDMA each user is assigned a unique code sequence it uses to encode its information-bearing signal. The receiver knowing the code sequences of the user, decodes the received signal after reception and recovers the original signal. This is possible because the crosscorrelations between the code of the desired user and the codes of the other users are small. Since the bandwidth of the code is chosen to be much larger than the bandwidth of the information-bearing signal, the encoding process enlarges (spreads) the spectrum modulation. The resulting signal is also called a spread-spectrum signal. A spread-spectrum must fulfill two criteria: 1) the transmission bandwidth must be larger than the information bandwidth, 2) the resulting radio-frequency bandwidth is determined by a function other than the information being sent. WCDMA is intended for deployment in the 2GHz frequency band where new spectrum bands will allow the full benefits of the technology to be exploited. For example, just one 5MHz WCDMA carrier will be able to handle mixed services, ranging in speed from 8 Kbit/s to 2 Mb/s, and user devices will be able to access several different services simultaneously. Future evolution of WCDMA will enable data rates higher than 2 Mb/s. Because the WCDMA radio interface uses a similar network signaling protocol structure to GSM and TDMA, the core switching layer of these existing networks can be partially reused for WCDMA. The wideband CDMA system uses 5 MHz. This bandwidth allows better performance in the presence of multipath since the receiver can separate the multipaths easier, to increase


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diversity and improve performance. The bandwidth also allows support of high rate services, up to 2 Mb/s peak rate. For wideband CDMA, the term uplink means transmission from the mobile to the base station. Similarly, the term downlink means transmission from the base station to the mobile. The key properties for general wideband CDMA include: - Improved performance over 2G systems (improved capacity, improved coverage, coherent

uplink using a user-dedicated pilot, fast power control in the downlink, seamless inter-frequency handover).

- High degree of service flexibility (multirate services: with maximums of 144-384 Kb/s for full coverage and 2 Mb/s for limited coverage, packet access mode).

- High degree of operator flexibility: support of asynchronous inter-base-station operation (for ETSI/ARIB WCDMA), support of different deployment scenarios, including hierarchical cell structure (HCS) and hot-spot scenarios, support of new technologies like multi-user detection (MUD) and adaptive antenna arrays (SDMA). Particularly, when WCDMA networks are completely rolled out, Mobile Internet will provide many types of new services and content over different networks and user devices, in a way that accommodates our personal preferences, location and circumstances at a particular moment. This means that the demands placed on the networks will be huge.

- Smooth evolution: WCDMA systems are based on GSM core network architecture. That means that owners of existing GSM infrastructure can integrate WCDMA technology into their networks, reducing upgrade costs and ensuring a faster rollout of new services.

2.4.5 Key technologies for UMTS Some of the critical technologies essential for the successful introduction of UMTS include the following.

2.4.5.1 UTRA The ETSI decision in January 1998 on the radio access technique for UMTS combined two technologies - WCDMA for paired spectrum bands and TD-CDMA for unpaired bands - into one common standard. This powerful approach ensures an optimum solution for all the different operating environments and service needs. The transmission rate capability of UTRA will provide at least 144 Kbt/s for full mobility applications in all environments; 384 Kb/s for limited mobility applications in the macro and micro cellular environments and 2 Mb/s for low mobility applications particularly in the micro and pico cellular environments. The 2 Mb/s rate may also be available for short range or packet applications in the macro cellular environment, depending on deployment strategies, radio network planning and spectrum availability.


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2.4.5.2 Multi-mode Second Generation/UMTS Terminals UMTS terminals will exist in a world of multiple standards and this will enable operators to offer maximum capacity and coverage to their user base by combining UTRA with second and other third generation standards. Therefore, operators will need terminals that are able to interwork with legacy infrastructures as well as other second generation world-wide standards, because they will initially have more complete coverage than UMTS.

2.4.5.3 Satellite Systems At initial service launch in 2002, the satellite component of UMTS will be able to provide a global coverage capability, to a range of user terminals. These satellite systems are planned to be implemented using the S-band Mobile Satellite Service (MSS) frequency allocations identified for satellite IMT-2000 and will provide services compatible with the terrestrial UMTS systems.

2.4.5.4 USIM Cards/smart cards A major step forward which GSM introduced was the Subscriber Identity Module (SIM) or Smart Card. It introduced the possibility of high security. SIM requirements, security algorithms, and card technology will continue to evolve up to and during the period of UMTS deployment. By 2002, the smart card industry will be able to offer cards with greater memory capacity, faster CPU performance, contactless operation and greater capability for encryption. These advances will allow the UMTS Subscriber Identity Module (USIM) to add to the UMTS service package by providing portable high security data storage and transmission for users. Contactless cards will permit much easier use than with today’s cards, for example allowing the smart card to be used for financial transactions and management such as electronic commerce or electronic ticketing without having to be removed from a wallet or phone. New memory technologies can be expected to increase card memory sizes making larger programmes and more data storage feasible. Several applications and service providers could be accommodated on one card.

2.4.5.5 Internet Protocol (IP) Compatibility UMTS is a modular concept that takes full regard of the trend towards convergence of fixed and mobile networks and services, enabling a huge number of applications to be developed. UMTS can support both IP and non-IP traffic in a variety of modes including packet, circuit switched and virtual circuit. UMTS will be able to benefit from parallel work by the Internet Engineering Task Force (IETF) within which the basic set of IP standards is extended to accommodate mobile communication.


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2.4.5.6 Cross platform interoperability The ability to transport multimedia content over various types of network, such as broadcast, telecommunications, and internet, requires industry to develop cross platform interoperability because the properties of the networks may have an impact on the content. In many cases several different kind of networks will be cascaded such as Ethernet, ATM, X25 and UMTS.

2.4.5.7 API and development toolbox The UMTS market will be driven by the rapid development and deployment of new and innovative services. The key enabler in this area will be the standardization of the UMTS Application Programming Interface (API). The API allows the abstraction of both the terminal and network, providing a generic way for applications to access terminals and networks. The API will allow the same application to be used on a wide variety of terminals and will also provide a common method of interfacing applications to UMTS networks. The API will support security, billing, subscriber information, service management, call management, SIM management user interaction and content translation. It will build upon and extend today's technologies such as Java, Wireless Application Protocol (WAP), GSM SIM Toolkit and Internet technologies which are also exploiting convergence with other emerging technologies such as digital TV set top boxes

2.4.5.8 Client-server architecture One of the primary drivers for UMTS is service differentiation, to allow network operators (and service providers) to market products based on more than just coverage and capacity issues. The key aspect is the ability to develop and offer new features in short timescales, without requiring modifications from infrastructure suppliers. Many new developments are based on a client/server technology, which allows intelligence to be downloaded transparently (from a server) into the user's terminal (the client), providing direct and immediate high-performance user interaction, validation and interpretation. Many examples of commercially successfully client/server solutions are to be found in the banking, travel and service industries, enabled by the growth in the use of desktop PC's and low cost networking links. For the mobile industry, intelligent terminals and USIM cards will allow personalization of the user interface and provision of features not possible with basic terminals in today's networks. With the increase in roaming traffic, the ability to provide such features independently of the serving network will become increasingly important. Existing and evolving GSM standards, such as SIM Toolkit and Mobile Execution Environment, together with other initiatives such as WAP, provide the framework for delivering this client/server approach.

2.4.5.9 Customer care and billing systems The new roles and many new players must inter-operate in a fully integrated manner. Customer care and billing systems are critical to commercial success. Customer care and


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billing are inextricably linked and must be able to effectively operate across all the players and roles in a customer friendly manner. UMTS deployment requires a harmonized solution to customer care and billing systems despite very different legacy practices. Significantly higher levels of automation and timeliness will be required to support the billing and customer care operations and in addition, fraud management will need to be applied across the whole value chain. Charging and billing will need different concepts to those typically available today.

2.4.6 European projects Several ACTS (Advanced Communications Technologies and Services) and IST (Information Society Technologies) projects were initiated in Europe to test and to validate various aspects related to UMTS, in particular we can cite the following projects: - INSURED (Integrated Satellite – UMTS Real Environment Demonstrator): the aim of this ACTS project is to demonstrate integrated S-UMTS (Satellite-UMTS) services in the context of an S-UMTS system trial involving real low-earth orbit satellites (IRIDIUM) and personal communications systems (using GSM technology). See http://www.sai.jrc.it/astron/space-compendium/ac229_insured.htm - SINUS (Satellite Integration into Networks for UMTS Services): The objective of this ACTS project is to integrate the complementary elements of satellite and terrestrial mobile systems to provide numerous services world-wide. It aims to validate the UMTS segment for different satellite air interfaces and interworking with terrestrial interfaces and B-ISDN. It also aims to assess the economic and technical feasibility of providing services through the UMTS satellite component. See http://www.sai.jrc.it/astron/space-compendium/AC212_SINUS.html - SUMO (Satellite-UMTS Multimedia Service Trials over Integrated Testbeds ): the aim of this ACTS project is to identify and demonstrate generic approaches to UMTS service support and network control, focusing on the satellite segment. The issues addressed are: (a) inter-operability between complementary satellite systems, both real and simulated, as well as with terrestrial core networks; (b) automatic selection of alternative access network resources in an integrated UMTS system depending on services and mobile environments (e.g. urban, rural); (c) advanced S-UMTS services based on e.g. bandwidth-on-demand flexibility of communications channels for application services. See http://www.sai.jrc.it/astron/space-compendium/sumo.html - SATIN (Satellite-UMTS IP-based Network): the objective of this IST project is to study the particular implications of the IP-based packet mode on the S-UMTS design, in the frame of


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the standard demand for high integration and seamless interworking with T-UMTS (Terrestrial UMTS). See http://www.ee.surrey.ac.uk/CCSR/IST/Satin/ REFERENCES http://www.umts-forum.org/

http://www.itu.int/home/imt.html

www.imt-2000-online.com/

ITU Rec. Q.1701 Framework for IMT-2000 networks, ITU, March 1999.

ITU Rec. Q.1711 Network functional model for IMT-2000, ITU, March 1999.

ITU Rec. Q.1721 Information flows for IMT-2000 capability set 1, ITU, June 2000

ITU Rec. Q.1731 Radio-technology independent requirements for IMT-2000 layer 2 radio interface, ITU, June 2000

ITU Rec. Q.1751 Internetwork signalling requirements for IMT-2000 capability set 1, ITU, June 2000

ITU Rec. Q.Qup30, Supplement to ITU-T Recommendation Q.1701: Specifications of international mobile telecommunications-2000 (IMT-2000), ITU, June 2000.

Fletcher P., “A European perspective on 3rd generation wireless technology and politics”, Electronic Design, 46(9), 72-75, April 1999.

LeinoA, “UMTS/IMT-2000 spectrum”, Telecommunications, 23(2), 35-43, February 1999.

McClelland B, “Mobilizing the third generation”, Telecommunications, 31(11), 50-54, April 1999.

Pentland S., “Planning for UMTS”, Telecommunication, 29(2), 36-42, February 1999.

Struthers K., “Bridging the generation gap”, Communication International (London), 24(3), 51-56, March 1998.

Richardson K.W., “UMTS overview”, Electronics 1 Communication Engineering Journal, pp. 93-100, June 2000.

Holma H. and Toskala A., “WCDMA for UMTS: radio access for the third generation mobile communications”, John Wiley and Sons, 2000. Prasad R. and Ojanperä T., “An overview of CDMA evolution toward wideband CDMA”, IEEE Communications Surveys, Fourth quarter 1998, Vol.1, n°1, pp. 2-29.


http://www.ee.surrey.ac.uk/CCSR/IST/Satin/

http://www.umts-forum.org/

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2.5 Cable Access Networks

2.5.1 Introduction - Cable TV Networks Cable TV networks were originally designed for one-way broadcast of television to consumers' homes. To ensure the reception of the cabled TV service with the same TV sets used to receive over-the-air broadcast TV, cable operators used a portion of the over-the-air radio frequency (RF) spectrum within sealed coaxial cables. With the emergence of attractive markets for data communication services, cable operators are migrating their networks to fully support data transmissions, by adapting their cable plants to support two-way broadband connectivity. Investments are justified because they face significant growth in consumers wishing to access the Internet and seek new opportunities in terms of value added services with valuable content that can be offered via local multimedia servers. The topology of cable TV networks are typically a mixture of a tree and branch bus. In the root of the tree is the cable TV provider or head-end systems that support point-to-multipoint communications up to the subscribers. Depending on the technology used within the cable TV networks, the usable bandwidth varies from 450MHz (all copper coax cable) to 750MHz (Hybrid Fiber-Coax), composed of channels of 6 or 8 MHz. Each standard television channel occupies 6 MHz of RF spectrum. Cable operators have the option to allocate the spectrum for downstream and upstream traffic. Usually the downstream channels are within the frequency range of 50-170MHz and the upstream channels within 5 to 42MHz.

2.5.2 Cable Modem Access Networks To deliver data services over a cable network, one of the 6 MHz television channel (in the 88 - 860 MHz range) is allocated for downstream traffic to customers and another channel (in the 5 - 42 MHz band) is used to carry upstream traffic. The transmission rates achieved are between 27 to 36Mbps (depending on the transmission technology 64 or 256 QAM), in the downstream, and between 320Kbps to 10.24Mbps in the upstream (with 16 QAM or QPSK modulation). These channels constitute a shared transmission medium among all the cable users of data services, typically 500 to 2,000 homes on a modern HFC cable network segment. In case of network congestion additional channels may be used to add more bandwidth for data services. Another option to increase the available bandwidth is to bring fiber-optic lines closer to neighborhoods. This reduces the number of homes served by each cable network segment, increasing the amount of bandwidth available to each end user. Cable modems are the devices used for the support of data over cable systems. They are typically connected to a two-way cable RF path over a low-split HFC cable system, and have typically two connections, one to the TV cable wall outlet and one to a computer.


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Most cable modems are external devices that connect to a personal computer (PC) through a standard 10Base-T Ethernet card or Universal Serial Bus (USB) connection, although internal PCI modem cards are also available. A cable modem termination system (CMTS) communicates with cable modems located in subscriber homes by creating a virtual local area network (LAN) connection within the cable network segment. The CMTS integrates the data upstream and downstream channels over a cable network segment and routes the traffic to the data backbone network. The number of channels can be adapted according to the number of users, required bandwidth and data rates and available spectrum.


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A cable headend combines the downstream data channels with the video channels and local programs to form a combined RF signal transmitted throughout the cable distribution network up to the subscribers’ households. Cable modems use connectionless technology, offering always on communications to the network similar to a corporate LAN.

2.5.3 Cable Access Network Architecture To offer data communications and IP based high-speed services, a cable operator creates a virtual data network that operates over its hybrid fiber/coax (HFC) infrastructure. The drawing below provides an overview of a typical large cable network offering multiservice data communications. A regional cable headend serves typically 200,000 to 400,000 homes in total, through the distribution hubs that are interconnected through a metropolitan fiber ring and each serving between 20,000 to 40,000 homes. At the distribution hubs signals are modulated onto analog carriers and then transported over fiber lines to fiber nodes serving via coaxial cable between 500 to 1,000 subscribers.


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2.5.3.1 Regional Cable Headend and the Distribution Hub The regional cable headend houses the local data network operations and management center. It comprises a carrier-class IP switch or router that interfaces with a backbone data network offering connectivity to the Internet, to local and remote content and application servers. The headend may also support IP telephony and a gateway to PSTN. The distribution hub is the interface point between the regional fiber network and the cable plant. It comprises the cable modem termination system (CMTS) that converts data from a wide area network (WAN) protocol, such as Packet Over SDH, into digital signals that are modulated for transmission over the HFC plant, and then demodulated by the cable modem in the home or business. The CMTS unit provides typically a dedicated 27 Mbps downstream data channel that is shared by the 500 to 1,000 homes served by a fiber node, or group of nodes. Upstream bandwidth per fiber node ranges typically from 500Kbps to 10 Mbps.


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2.5.3.2 Subscriber Interface A splitter within the subscribers’ homes segments the coaxial cable lines between the cable modem and the TV outlets. Cable modems connect to an Ethernet card in the PC with UTP5 cabling and RJ-45 connectors, or Universal Serial Bus (USB) connections. In a business environment, the cable modem interfaces with a local area network (LAN) through an Ethernet hub, switch or router.


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2.5.4 Introduction to Data Over Cable Systems Data over cable systems add to cable TV networks data communications capabilities. Specifications for data over cable system include data communications elements, operations and business support elements for security, configuration, performance, fault, and accounting management. Two international standards have emerged for cable modem products: DOCSIS, which is the standard in North America and in other International markets, and DVB/DAVIC EuroModem, in Europe. The ITU has adopted at the international level the DOCSIS standards. The DOCSIS specifications 1.0 and 1.1 (Data-Over-Cable Service Interface Specifications) by CableLabs (www.cablemodem.com) certify cable modems and qualify CMTSs (Cable Modem Termination Systems) for interoperability. They define interface requirements for cable modems involved in high-speed data distribution over cable television system networks. The specifications are intended to be non-vendor specific, allowing cross-manufacturer compatibility. Certification provides the assurance that the cable modem complies with the DOCSIS specification and will interoperate with other certified modems and qualified headend systems. Qualification ensures the cable operator or broadband service provider that the headend equipment will interoperate with certified cable modems.


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2.6 Optical Ethernet

2.6.1 Overview The actual scenario is made up of the four basic network configurations that are being deployed nowadays, to say, Local Area Networks (LANs), Campus Area Networks (CANs), Metropolitan Area Networks (MANs) and Wide Area Networks (WANs), each of them with a wider scope than its predecessor. Regarding LAN environment, today few optical Ethernet links are implemented within a computer room or a small building. But there are exceptions for electrically noisy environments, highly secure transmissions and ground isolation. This situation is likely to change, as very-short-reach optics support much higher speeds than copper does. It is important to note that gigabit copper links are limited to about 30 meters and that the next generation of Ethernet at 10 Gigabits would drop this already inadequate distance dramatically. CAN scenario is dominated by multimode fiber, although most CANs are really multiple LANs interconnected by routers that use optical links. This situation is changing, as the scale and functional capabilities of Ethernet switches increase. More and more LANs are being implemented with Ethernet switches, providing separate switch ports to every node on the LAN. This trend is being accelerated by the proliferation of virtual LAN (VLAN) capable Ethernet switches and by the development of even larger and more capable routers that understand and route to VLAN IDs in the now larger LAN. Optical Ethernet in the MAN is a relatively recent development. Gigabit optical Ethernet has the capacity to provide direct Ethernet services as a carrier offering; with service switches that limit actual delivered bandwidth as needed. Multiple vendors now offer direct Ethernet services to subscribers, with only a few core routers linking those subscribers to the outside world, the Internet. Two reasons are leading to implement Ethernet MANs today, so called “Ethernet services” and the desire to reduce the number of routers in the network as unnecessary ones add delay to the packet transport, and also maintenance is complex and needs people. The routing network is much more effective and easier to manage if all of the entities’ routers are directly interconnected, which is easily done today using optical Ethernet. Ethernet transport has not yet taken off in the long-haul network, but this is expected to change as 10-Gigabit Ethernet interfaces become available. Some of these are expected to operate at some SONET speeds and at the distances needed for long-haul networks. Today several vendors have products that aggregate and transport Ethernet traffic at 10-Gigabit


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speeds suitable for the WAN, although they still are proprietary and require matching devices of the same vendor at each end. Optical Fast Ethernet emerged from the 100-Megabits Ethernet, following the copper standard and doing some adaptation work from fiber distributed data interface (FDDI) technology. The transceiver design and encoding technique were the same, simplifying the work of standardization and assuring that the technology would actually work. Gigabit Ethernet standard IEEE 802.3z describes multiple optical specifications, 1000BASE-SX and 1000BASE-LX describe short and long wavelength transmission methods over both multi-mode and single-mode fiber, and the transceivers and encoding formats are based again on fiber channel. The separation of the Ethernet control logic from the media control logic is achieved by the Gigabit Interface Converter (GBIC) module, that provides a hot-swappable way of changing the accessed media to support different Ethernet networks. The GBIC module is speeding up the deployment of optical Ethernet. An all-optical network can be accomplished by today’s technology in one way: optical Ethernet switches, in the sense that all interface ports are optical but switching is done electrically, are working and it is the technology used by carriers selling Ethernet services. As the fiber will continue to get into consumer premises, these services will reach the final consumer more easily. Wavelength Division Multiplexing (WDM) and Dense WDM (DWDM) technology is the de facto standard for core transport applications. By multiplexing many wavelengths of light onto fiber-optic cable, service providers are able to transport mass amounts of data over very long distances. Because metro DWDM solutions are derived from their more expensive upstream cousins in the core networks, they are still very expensive to deploy and difficult to manage. The technology is based mainly in the IEEE 802.3something standards but manufacturers are leading the innovations in this field, they are organized into the 10-Gigabit Ethernet Alliance (10GEA). IEEE 802.3ae 10-Gigabit Ethernet Standard is due to be finished and approved by 1st Quarter 2002.

2.6.2 Competing Technologies

2.6.2.1 XDSL Asymmetric digital subscriber line (ADSL), the xDSL front runner, will be able to provide from 1.5 to 7 Mbps downstream and from 200 kbps to 1 Mbps upstream of data to customers using the existing telephone company's twisted pair copper wires. Low cost application specific integrated circuit (ASIC) from leading semiconductor houses promise declines in the


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price of second and third generation ASDL modems, and the Universal ADSL Working Group (UAWG), which is backed by a leaders companies of the networking, telecommunications, computing and semiconductor industries, is working toward resolving a lack of interoperability. The UAWG's work should also help bring about lower cost modems.

2.6.3 Cable modems The other leading technology in the race to bring broadband capacity to users, cable modem service, can provide data rates of up to 36 Mbps downstream. However, because media is shared, experts consider speeds of 10 Mbps downstream and 200 kbps to 2 Mbps upstream (for two-way modems) more realistic. Some major cable providers appear to be more interested in digital CATV and telephony rather than on upgrading infrastructure to be two-way cable modem capable. Regardless, the technology is available today and it works. Expansion is expected in coverage as well.

2.6.4 Satellite Systems In addition to ADSL and cable modem providers, satellite system operators plan to offer two-way data services to users around the world. Published expected data rates of the various satellite constellations vary between 200 kbps to 2 Mbps downstream/ upstream for residential users and from 10 Mpbs to 30 Mbps for corporate users. Satellite systems are best suited for providing access to areas which are sparsely populated and which lack other alternatives.

2.6.5 LMDS LMDS is a broadband wireless point-to-multipoint communication system operating above 20 GHz (depending on country of licensing) that can be used to provide digital two-way voice, data, Internet, and video services. LMDS provides an effective last-mile solution for the incumbent service provider and can be used by competitive service providers to deliver services directly to end users.

2.6.6 38 GHz radio Sometime referred to as a coaxial pipeline in the sky, 38 Gigahertz radio is operating successfully in several major metro areas. To date, it has primarily been used to provide other telecommunications carriers with additional capacity. However, a shift to point-to-multipoint networks and the resulting use of low-cost CPE (Customer Premises Equipment) should translate in a rapid customer expansion. Most importantly, 38 GHz radio is operational nowadays.


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2.7 Third-generation mobile communication systems

2.7.1 Introduction 3rd generation mobile or 3G mobile corresponds to the generic term for the next generation of mobile communications systems that will provide enhanced voice, text and data services when compared with the mobile services available today. The technology concepts and standards for the 3rd generation systems and services are under development by a global partnership, named the 3G Partnership Project (3GPP), that spans industry wide and involves many related organizations. The vision of 3G is based on the evolution of current standards, such as GSM and CDMA, with the extensions and enhancements to support high speed and multimedia data services. The systems will enable users of current 2nd generation mobile networks to migrate easily to the 3rd generation services, with minimal disruption. Additional radio spectrum is also required to support the enhanced services. The evolution of current systems towards 3G will be processed as part of the ITU's IMT-2000 family of mobile communication systems. The ultimate goal for 3G is to unify the disparate standards that today's 2nd generation wireless networks use, and to target a single network standard to be agreed and implemented instead of different network types being adopted in the Americas, Europe and Japan. But it seems currently likely that there will be up to 3 types of technology deployed in 3rd generation mobile systems. Through the work of organizations such as the ITU and 3GPP it is expected that those systems would be harmonized to ensure that they are compatible, can co-operate, and will accept multi-mode handsets. At the same time the integration of systems and services shall offer users with worldwide roaming.

2.7.2 The IMT-2000 concept IMT-2000 means International Mobile Telecommunication-2000 and it encompasses a concept designed to address all the difficulties that are expected to be solved by the 3rd generation mobile systems:

• Integrated Mobile Communications Services. • Global roaming (from anywhere to anywhere in the world). • Mobility-services for customers with different handsets in diverse wireless

environments. • High quality multimedia services via broadband networks.


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2.7.3 Mobile Data Services and Applications Speed 9.6Kbps 64Kbps 384Kbps 2Mbps

Market Sector

------------------------------------------------------------------------------------------------------------------------------ Lower Speeds Higher Speeds


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Mass Consumer (Horizontal market)

SMS Internet Access (Email and Web) Document exchange On-line transactionsFinancial services and on-line banking

Global information services Directories access (e.g. phone) Rental services Security and emergency services E-commerce with image catalog tele-shopping

Basic multimedia services (e.g. videoconferencing) Audio services (e.g. music) Electronic publications (journals and newspapers) Advertisement (static images)

Advanced multimedia services Full multimedia communication services Entertainment (e.g. video on demand, video games, karaoke) Training (e.g. distance learning)

Corporate (Vertical market)

Corporate Host Access Wireless email, Web, database, file transfer. Distribution information services (e.g. WAP)

Mobile Business Internet/Intranet access Web services Basic VPN support Distant monitoring and control services

Multimedia Services Videoconferencing Multimedia mail-based services Teleworking Road/traffic information

Multimedia-based communication services High-quality multipoint videoconferencingMultimedia telephone Distant medical services Small mobile office/Home office

2.7.4 3G Data Rates The ITU established the minimum requirements for the data speeds that the IMT-2000 standards must support, that were defined according to the degree of mobility involved when the 3G call is being made.


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Mobility Minimum Speed Degree of mobility

Environment

High 144Kbps More than 120Km/hour

Outdoor

Full 384Kbps Less than 120Km/hour

Outdoor

Limited 2 Mbps Less than 10Km/hour

Stationary indoor Short range outdoor

2.7.4.1 3G Technology evolution


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2.7.5 Relevant players

2.7.5.1 GSM Association It is the world's largest organization of mobile wireless operators, regulators and industry bodies that work together to ensure global roaming and inter-operability of GSM services and networks. While GSM continues to evolve, with high-bandwidth services enhancing the 2nd generation technologies, it is the focal point for 3rd generation systems and operators, with the mandate and mission to manage all common and inter-operator issues.

2.7.5.2 3G Partnership Program (3GPP) It is the global partnership created in December 1998, following an agreement between six standards setting bodies around the world including ETSI, ARIB and TIC of Japan, ANSI of the USA and the TTA of Korea, to become responsible for establishing, producing and maintaining the 3rd generation technical specifications and ensuring there are provisions for interoperability and compatibility between 3rd generation systems and existing systems and services.

2.7.5.3 UMTS Forum It is a forum of different players related to the UMTS systems, that it is focused on spectrum availability, licensing issues, and long-term market surveys for 3rd generation systems.


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2.7.5.4 Standards for 3G mobile systems The standardization process of 3G systems started when in 1998 the International Telecommunication Union (ITU) called for radio transmission technology (RTT) proposals for IMT-2000 (originally called Future Public Land Mobile Telecommunications Systems (FPLMTS)), the formal international name for the third generation standard. Different proposals were submitted, TDMA-based and wideband CDMA-based, the later in particular in the form of two main submissions, Wideband CDMA (WCDMA) and cdma2000. They were supported respectively by the European community and the North American CDMA community.

The ITU adopted for the IMT-2000 standard a CDMA-based approach that encompasses three optional modes of operation. Those transmission modes would also have to be supported over the two major core network standards defining the network architectures, GSM MAP and TIA IS-41: Mode Option Origin Supporters

1

IMT DSWCDMADirect Spread FDD (Frequency Division Duplex)

Based on the 1st operational mode of ETSI's UTRA (3G Terrestrial Radio Access) RTT proposal

Japan's ARIB (Association of Radio Industries and Businesses) standards setting body GSM network operators and vendors. To be deployed in Japan and Europe.

2 IMT MCcdma2000Multi- Based on the cdma2000 RTT cdmaOne operators and members of


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Carrier FDD (Frequency Division Duplex)

proposal from the US Telecommunications Industry Association (TIA).

the CDMA Development Group (CDG). Likely to be deployed in the USA.

3

IMT TCUTRA TDD (Time Division Duplex)

Based on 2nd second operational mode of ETSI's UTRA (3G Terrestrial Radio Access) RTT proposal.

Band solution more appropriate for indoor cordless communications. It is harmonized with the Chinese TD-SCDMA RTT proposal. Likely to be deployed in China.

2.8 Fast Ethernet 100-Mbps Ethernet is a high-speed LAN technology that provides high bandwidth to desktop users, as well as to servers and server clusters in data centers. 100BaseT is based on the IEEE 802.3 CSMA/CD specification. 100BaseT keeps the IEEE 802.3 frame format, size, and error-detection mechanism. It supports also every applications and networking software that are used on 802.3 networks. 100BaseT supports dual speeds of 10 and 100 Mbps using 100BaseT fast link pulses (FLPs). 100BaseT hubs must detect dual speeds, but adapter cards can support 10 Mbps, 100 Mbps, or both.

2.8.1 Signaling issue 100BaseT supports two signaling types: 100BaseX

• 4T+ Both of them are interoperable at the station and hub levels. The media-independent interface (MII), an AUI-like interface, provides interoperability at the station level. The hub provides interoperability at the hub level. The 100BaseX-signaling scheme has a convergence sublayer that adapts the full-duplex continuous signaling mechanism of the FDDI physical medium dependent (PMD) layer to the half-duplex, start-stop signaling of the Ethernet MAC sublayer. 100BaseTX's use of the existing FDDI specification has allowed quick delivery of products to market. 100BaseX is the signaling scheme used in the 100BaseTX and the 100BaseFX media types. The 4T+-signaling scheme is based on one pair of wires used for collision detection and the other three pairs used to transmit data. 100BaseT can then run over existing Category 3 cabling if all four pairs are installed to the desktop. 4T+ is the signaling scheme used in the 100BaseT4 media type, and it supports half-duplex operation only.

2.8.2 Hardware Components used for a 100BaseT physical connection are: Physical Medium: This device carries signals between computers and can be one of three 100BaseT media types that are 100BaseTX, 100BaseFX and 100BaseT4


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• Medium-Dependent Interface (MDI): This is a mechanical and electrical interface between the transmission medium and the physical-layer device.

• Physical-Layer Device (PHY): The PHY provides either 10 or 100 Mbps operation and can be a set of integrated circuits (or a daughter board) on an Ethernet port, or an external device supplied with an MII cable that plugs into an MII port on a 100BaseT device (similar to a 10 Mbps Ethernet transceiver).

• Media-Independent Interface (MII): The MII is used with a 100 Mbps external transceiver to connect a 100 Mbps Ethernet device to any of the three media types. The MII has a 40-pin plug and cable that stretches up to 0.5 meters.

2.8.3 Media Types 100BaseT supports three media types at the OSI physical layer (Layer 1): 100BaseTX, 100BaseFX,

• 100BaseT4. Characteristics of 100BaseT Media Types: Type Cable Nb of

pairs / strands

Connector Max. segment length

Max. network diameter

100BaseTX Category 5 UTP, or Type 1 and 2 STP

2 pairs ISO 8877 (RJ-45) connector

100 m. 200 m.

100BaseFX 62.5/125 micron multi-mode fiber

2 strands Duplex SC media-interface connector (MIC) ST

400 m. 400 m.

100BaseT4 Category 3, 4, or 5 UTP

4 pairs ISO 8877 (RJ-45) connector

100 m. 200 m.

2.8.3.1 100BaseTX 100BaseTX is based on the TP-PMD (Twisted Pair-Physical Medium Dependent) specification of ANSI (American National Standards Institutes). UTP and STP cabling are supported by this specification supports. 100BaseTX uses the 100BaseX-signaling scheme over 2-pair Category 5 UTP or STP. The IEEE 802.3u specification for 100BaseTX networks allows a maximum of two repeater/hub per networks and a total network diameter of about 200 meters. A link segment, which is defined as a point-to-point connection between two Medium Independent Interface (MII) devices, can be up to 100 meters.

2.8.3.2 100BaseFX 100BaseFX is based on the ANSI TP-PMD X3T9.5 specification for FDDI LANs. 100BaseFX uses the 100BaseX-signaling scheme over two-strand multimode fiber-optic


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(MMF) cable. The IEEE 802.3u specification for 100BaseFX networks allows data terminal equipment (DTE)-to-DTE links of approximately 400 meters, or one repeater network of approximately 300 meters in length.

2.8.3.3 100BaseT4 100BaseT4 allows 100BaseT to run over existing Category 3 wiring, provided that all four pairs of cabling are installed to the desktop. 100BaseT4 uses the half-duplex 4T+-signaling scheme. The IEEE 802.3u specification for 100BaseT4 networks allows a maximum of two repeater (hub) networks and a total network diameter of approximately 200 meters. A link segment, which is defined as a point-to-point connection between two MII devices, can be up to 100 meters.

2.8.4 Operation aspects 100BaseT uses the same IEEE 802.3 MAC access and collision detection methods then 10BaseT, and both also have the same frame format and length requirements. The main difference between 100BaseT and 10BaseT (other than the obvious speed differential) is the network diameter. The 100BaseT maximum network diameter is 205 meters, which is about 10 times less than 10 Mbps Ethernet. This reduction is necessary because 100BaseT uses the same collision-detection mechanism as 10BaseT. With 10BaseT, distance limitations are defined so that a station knows while transmitting the smallest legal frame size (64 bytes) that a collision has taken place with another sending station that is located at the farthest point of the domain. To achieve the increased throughput of 100BaseT, the size of the collision domain had to shrink. This is because the propagation speed of the medium has not changed, so a station transmitting 10 times faster must have a maximum distance that is 10 times less. As a result, any station knows within the first 64 bytes whether a collision has occurred with any other station.

2.8.4.1 FLPs 100BaseT uses pulses, called FLPs, to check the link integrity between the hub and the device. FLPs are backward compatible with 10BaseT normal-link pulses (NLPs). But FLPs contain more information than NLPs and are used in the autonegotiation process between a hub and a device on a 100BaseT network.

2.8.4.2 Autonegotiation Option 100BaseT networks support an autonegotiation option. This option enables a device and a hub to exchange information (using 100BaseT FLPs) about their capabilities, thereby creating an optimal communications environment. Autonegotiation supports a number of capabilities, including speed matching for devices that support both 10-and 100-Mbps operations, full-duplex mode of operation for devices that support such communications, and an automatic signaling configuration for 100BaseT4 and 100BaseTX stations.


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2.9 LMDS

2.9.1 Overview LMDS is a broadband wireless point-to-multipoint communication system operating above 20 GHz (depending on country of licensing) that can be used to provide digital two-way voice, data, Internet, and video services (see Figure 1).

Figure 1. LMDS system. The acronym LMDS is derived from the following:

• L (local)—denotes that propagation characteristics of signals in this frequency range limit the potential coverage area of a single cell site. Ongoing field trials conducted in metropolitan centers place the range of an LMDS transmitter at up to 8 Km.

• M (multipoint)—indicates that signals are transmitted in a point-to-multipoint or broadcast method The wireless return path, from subscriber to the base station, is a point-to-point transmission.

• D (distribution)—refers to the distribution of signals, which may consist of simultaneous voice, data, Internet, and video traffic.

• S (service)—implies the subscriber nature of the relationship between the operator and the customer. The services offered through an LMDS network are entirely dependent on the operator's choice of business.

Point-to-point fixed wireless networks have been commonly deployed to offer high-speed dedicated links between high-density nodes in a network. More recent advances in a point-to-multipoint technology offer service providers a method of providing high-capacity local access that is less capital-intensive than a wireline solution, faster to deploy than wireline, and able to offer a combination of applications. Moreover, as a large part of a wireless network's cost is not incurred until the customer premises equipment (CPE) is installed, the network


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service operator can time capital expenditures to coincide with the signing of new customers. LMDS provides an effective last-mile solution for the incumbent service provider and can be used by competitive service providers to deliver services directly to end users. Benefits can be summarized as follows:

• lower entry and deployment costs. • ease and speed of deployment (systems can be deployed rapidly with minimal

disruption to the community and the environment). • fast realization of revenue (as a result of rapid deployment). • demand-based buildout (scalable architecture employing open industry standards

ensuring services and coverage areas can be easily expanded as customer demand warrants).

• cost shift from fixed to variable components. With traditional wireline systems, most of the capital investment is in the infrastructure, while with LMDS a greater percentage of the investment is shifted to CPE, which means an operator spends money only when a revenue-paying customer signs on.

• no stranded capital when customers churn. • cost-effective network maintenance, management, and operating costs

2.9.2 Technical Aspects LMDS occupies the largest chunk of spectrum ever devoted to any one service. Located in sections of the 27.5 to 31.3 GHz band, LMDS can consist a bandwidth of up to 1.3 GHz. Via the transmission of microwave signals, LMDS networks can provide two-way broadband services including: • Video, • High-speed Internet access, and • Telephony services. A LMDS network can be composed of a series of cells that each deliver point-to-multipoint services to subscribers. Each transmitter in a cell serves a relatively small area, about two to three miles in diameter. This small cell size means that the LMDS network requires a large number of antennas. As cellular experience has shown, this can be troublesome, since there are only so many places where antennas and hub equipment can be installed. Network Architecture. Various network architectures are possible within LMDS system design. The majority of system operators will be using point-to-multipoint wireless access designs, although point-to-point systems and TV distribution systems can be provided within the LMDS system. It is expected that the LMDS services will be a combination of voice, video, and data. Therefore, both asynchronous transfer mode (ATM) and Internet protocol (IP) transport methodologies are practical when viewed within the larger telecommunications infrastructure system of a nation. The LMDS network architecture consists of primarily four parts: network operations centre (NOC), based-based infrastructure, base station, and CPE (Customer Premises Equipment).


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• The NOC contains the network management system (NMS) equipment that manages large

regions of the customer network. Multiple NOCs can be interconnected. • The based-based infrastructure typically consists of synchronous optical network

(SONET), optical carrier (OC)–12, OC–3, and DS–3 links, central-office (CO) equipment, ATM and IP switching systems, and interconnections with the Internet and public switched telephone networks (PSTNs).

• The base station is where the conversion from fibered infrastructure to wireless infrastructure occurs. Base-station equipment includes the network interface for based termination, modulation and demodulation functions and microwave transmission and reception equipment typically located atop a roof or a pole. Key functionalities which may not be present in different designs include local switching. If local switching is present, customers connected to the base station can communicate with one another without entering the based infrastructure. This function implies that billing, channel access management, registration, and authentication occur locally within the base station.

The alternative base-station architecture simply provides connection to the based infrastructure. This forces all traffic to terminate in ATM switches or CO equipment somewhere in the based infrastructure. In this scenario, if two customers connected to the same base station wish to communicate with each other, they do so at a centralized location. Billing, authentication, registration, and traffic-management functions are performed centrally.

• The customer-premises configurations will include outdoor-mounted microwave equipment and indoor digital equipment providing modulation, demodulation, control, and customer-premises interface functionality. The CPE may attach to the network using time-division multiple access (TDMA), frequency-division multiple access (FDMA), or code-division multiple access (CDMA) methodologies. The customer premises interfaces will run the full range from digital signal, level 0 (DS–0), plain old telephone service (POTS), 10BaseT, unstructured DS–1, structured DS–1, frame relay, ATM25, serial ATM over T1, DS–3, OC–3, and OC–1. The customer premises locations will range from large enterprises (e.g., office buildings, hospitals, campuses), in which the microwave equipment is shared between many users, to mall locations and residences, in which single offices requiring 10BaseT and/or two POTS lines will be connected. Obviously, different customer-premises locations require different equipment configurations.

Standards. As LMDS wireless access systems evolve, standards will become increasingly important. Standards activities currently underway include activities by the ATM Forum, the Digital Audio Video Council (DAVIC), the European Telecommunications Standards Institute (ETSI), and the International Telecommunications Union (ITU). The majority of these methods use ATM cells as the primary transport mechanism. Data rates. The system may provide, at a minimum, the following general services: Voice: The system may provide full switched toll grade quality voice service. The voice quality may be telephone toll grade or better and there may be no delays in speech that are


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perceptible to the user. The user may interface with the system by a standard method or means typically being an RJ-11 standard telephone jack employing their own standard telephone in the case of a residential user. The voice user is not expected to change any of their infrastructure interfaces. The "normal" telephone connection may be provided by means of the LMDS local interface unit, the LIU. The LIU may be compatible with any and all normal accepted telephone interfaces. Low Speed Data: The system may be able to provide data at the rates of 1.2 to 9.6 Kbps on a transparent basis and have this data stream integrated into the overall network fabric. The system may handle all data protocols necessary in a transparent fashion. The network may allow local access to value added networks from the local access point. The low speed data may be provided for over a standard voice circuit from the users premises as if there were no special requirement. There may be toll grade or better quality. The system may also be capable of support all Group 3 fax services. Medium Speed Data: The network may be able to handle medium speed data ranging from 19.2 to 64 Kbps. The interfaces for such data may be value added network local nodes. The medium speed data may be provided for over a standard voice circuit from the users premises as if t here were no special requirement. There may be toll grade or better quality. The interconnection for 64 Kbps may also be ISDN compatible. High Speed Data: Data rates at and in excess of 1.544 Mbps may also be provided on an as needed basis and a dedicated basis. The data rates may be between 1.544 Mbps and a maximum of 155 Mbps. Also it may be required to provide access to such high speed data services as Fast Ethernet and FDDI at 100 Mbps. This may require both physical layer interfaces and the datalink and network layers as specified in the particular protocol. The system must also support multiple layer protocols including TCP/IP. Also the data must be point-to-point, point to multipoint, and multi point to multi point. Video: The network may be able to provide the user with access to analog and digitized video services. This may also enable the provisioning of interactive video services. The video services may enable a system with a minimum number of channels of 150 video channels of remote programming; ten of local off-air programming, and 20 locally generated programming. The interactive video may allow for ten channels of pay per view at a minimum, and interactive channels for local information selection. Video must also support such tiered services as basic, premium, pay per view, and interactive. The inputs to the system are from such sources as off-air, local generated, satellite, and other sources. Sources may be analog or digital, encrypted or not.

2.9.2.1 Competing Technologies XDSL. Asymmetric digital subscriber line (ADSL), the xDSL front runner, will be able to provide from 1.5 to 7 Mbps downstream and from 200 kbps to 1 Mbps upstream of data to customers using the existing telephone company's twisted pair copper wires. Low cost application specific integrated circuit (ASIC) from leading semiconductor houses promise declines in the


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price of second and third generation ASDL modems, and the Universal ADSL Working Group (UAWG), which is backed by a leaders companies of the networking, telecommunications, computing and semiconductor industries, is working toward resolving a lack of interoperability. The UAWG's work should also help bring about lower cost modems. Cable modems. The other leading technology in the race to bring broadband capacity to users, cable modem service, can provide data rates of up to 36 Mbps downstream. However, because media is shared, experts consider speeds of 10 Mbps downstream and 200 kbps to 2 Mbps upstream (for two-way modems) more realistic. Some major cable providers appear to be more interested in digital CATV and telephony rather than on upgrading infrastructure to be two-way cable modem capable. Regardless, the technology is available today and it works. Expansion is expected in coverage as well. Satellite Systems. In addition to ADSL and cable modem providers, satellite system operators plan to offer two-way data services to users around the world. Published expected data rates of the various satellite constellations vary between 200 kbps to 2 Mbps downstream/ upstream for residential users and from 10 Mpbs to 30 Mbps for corporate users. Satellite systems are best suited for providing access to areas which are sparsely populated and which lack other alternatives. Based optic. The other land-based alternative, based optic cable to the home or curb, is too expensive and deployed only to heavy business users. Full installation of based in the local loop would require at least 20 to 25 years to be completed. Competitive local exchange carriers (CLECs), including long distance giants continue to establish based in densely populated areas, and these systems are already operational. However, extension of this capability beyond heavy business users is unlikely. Despite a pipeline of several hundred megabits or even gigabits to each user, the cost of based deployment to the home, will preclude wide spread installation for some time. 38 GHz radio. Sometime referred to as a based pipeline in the sky, 38 Gigahertz radio is operating successfully in several major metro areas. To date, it has primarily been used to provide other telecommunications carriers with additional capacity. However, a shift to point-to-multipoint networks and the resulting use of low-cost CPE (Customer Premises Equipment) should translate in a rapid customer expansion. Most importantly, 38 GHz radio is operational nowadays.


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3 Issues to be considered for the choice of Access technology

3.1 Applications and Services - QoS for applications being used

- Voice - Data - Video

3.1.1 Services supported within Cable Modem Access Networks Data over cable networks allow the deployment of broadband cable data services, for which high-speed Internet access is the dominant service. Other data services include IP telephony, the access to business content and application servers such as streaming audio and video servers, local content (community information and services), and CD-ROM/DVD servers.

3.2 Network requirement - Legacy networks and infrastructure - Network Management - Provision of BW - Ease of deployment and maintenance - Cost benefits - Resilience and availability - Interfaces - Interfacing and interoperating with the core network

3.3 Network architecture and access network functionality - Protocol stack issue


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4 Standards related to Access Networks 4.1 Standards Bodies

- ETSI - IEEE - ITU-T - ITU-R - BWIF - CEPT - IETF - ATM Forum - ADSL Forum - …

4.2 Cable Modem Standards and Specifications

4.2.1 The DOCSIS Standard The Institute of Electronic and Electrical Engineering (IEEE) 802.14 Cable TV Media Access Control (MAC) and Physical (PHY) Protocol Working Group was formed in May 1994 by vendors to develop an international cable modem standard. Because of long delays by IEEE802.14 to deliver its standard, the North American cable operators decided to form a partnership called Multimedia Cable Network System Partners Ltd. (MCNS) to research and publish their own cable modem system specifications. MCNS released its draft standard, called the Data Over Cable Service Interface Specification (DOCSIS 1.0), in March 1997. First public demonstrations of DOCSIS equipment interoperability were held late 1997.


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The DOCSIS standards comprise specifications covering several areas, such as: Cable Modem to Customer Premise Equipment Interface Cable Modem Termination System – Network Side Interface Radio Frequency (RF) Interface Specification Security (Baseline Privacy Interface) Operations Support System Interface (OSSI)


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CableLabs began in 1998 formal certification programs for DOCSIS 1.0 cable modem equipment compatibility to the specifications and interoperability, and qualification of CMTS equipment. The ITU accepted DOCSIS 1.0 in March 1998 as an international cable modem standard, called ITU J.112. From April 1999 CableLabs issued DOCSIS 1.1 as a second-generation specification that adds to DOCSIS 1.0 improved QoS and hardware-based packet-fragmentation capabilities for IP telephony and constant-bit-rate services support. This standard is treated in more detail in section [xxxx]. The ITU accepted DOCSIS 1.1 as an international cable modem standard, called ITU J.114, which has been adopted worldwide and it is ensuring international interoperability of data signals. CableLabs is considering a third version of the DOCSIS standard, called DOCSIS 2.0, by incorporating an advanced PHY to the core specifications to increase upstream transmission capacity and reliability to noise by using advanced physical layer modulation techniques. The process of development of the specifications is under way and it is expected to complete before the end of 2001. DOCSIS 2.0 will be compatible with DOCSIS 1.0 and 1.1 cable modems and CMTS and work in the same upstream and downstream physical channels.

DOCSIS Roadmap


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DOCSIS Version Features, Benefits, Application services DOCSIS 1.0 (5 Mbps upstream)

General purpose retail use Basic standard core specifications High speed data services Internet access

DOCSIS 1.1 (10 Mbps upstream)

Support of QoS Packet fragmentation Pre-equalization Security features Enhanced operations Tiered service IP telephony and multimedia applications

DOCSIS 2.0 (30 Mbps upstream)

Improved modulation techniques Robustness to noise Symmetric services Peer-to-peer Business-to-business

More than 30 vendors are currently building DOCSIS cable modem products. [Cable Television Laboratories Inc. launched in 1997 the OpenCable project to set standards for interactive digital cable set-top boxes. The MPEG-2 (Moving Picture Experts Group) standard is specified for digital video transport with audio following the Dolby Audio AC-3 system. For signal security, OpenCable selected the DES encryption standard, with the support of multiple conditional access and control data streams over the core encryption scheme. No single vendor’s microprocessor or operating system (OS) is specified, enabling most interactive services to be implemented with middleware using open Internet specifications.] More information on the DOCSIS standards is available online at http://www.cablelabs.com

4.2.2 The DVB/DAVIC EuroModem Standard In Europe, the Digital Audio Video Council (DAVIC) issues the Digital Video Broadcast (DVB) specifications for digital set-tops and for cable modems. The DVB/DAVIC cable modem specifications, “EuroModem”, are an alternative to DOCSIS and were established to better fit the European set-top devices. A similar entity to CableLabs,


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the EuroCableLabs (ECL) operates under the direction of the European Cable Communications Association (ECCA). The DVB 2.0 specifications, adopted by the European Telecommunications Standards Institute (ETSI) as ETS 300800, were also selected by DAVIC as the DAVIC 1.5 specifications for cable modems. They describe the out-of-band and in-band transmission options applicable to interactive set-top boxes and cable modems for the deployment of interactive TV, data and voice services over a common cable network platform. The ECCA/ECL issued its DVB/DAVIC-based EuroModem specifications in May 1999. With support by more than 20 vendors, DVB/DAVIC is challenging DOCSIS dominance in Europe. A DVB/DAVIC Interoperability Consortium was formed by vendors to foster open standards and compatibility for EuroModems, and to perform interoperability certification. More information on the EuroModem standard is available online at http://www.eurocablelabs.com/EuroModem.html

4.2.3 Security on cable modems

The DOCSIS specifications provide a baseline privacy that guarantees user data privacy (across the cable network) and services protection by encrypting CM/CMTS traffic flows and controlling distribution of encryption keys to CMs. The DOCSIS system architecture includes security components that ensure user data privacy across the shared-medium cable network and prevents unauthorized access to DOCSIS-based data transport services across the cable network. The DOCSIS architecture also supports the policing (e.g., filtering) functions that can be used to reduce risks from attacks targeted at attached CPE devices.

4.3 Fast Ethernet The IEEE Higher Speed Ethernet Study Group was formed to assess the feasibility of running Ethernet at speeds of 100 Mbps. The Study Group established several objectives for this new higher-speed Ethernet but disagreed on the access method. At issue was whether this new faster Ethernet would support CSMA/CD to access the network medium or some other access method. The study group divided into two camps over this access-method disagreement: the Fast Ethernet Alliance and the 100VG-AnyLAN Forum. Each group produced a specification for running Ethernet (and Token Ring for the latter specification) at higher speeds: 100BaseT and 100VG-AnyLAN, respectively.


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100BaseT is the IEEE 802.3u specification for the 100-Mbps Ethernet implementation over unshielded twisted-pair (UTP) and shielded twisted-pair (STP) cabling. The Media Access Control (MAC) layer is compatible with the IEEE 802.3 MAC layer. 100VG-AnyLAN is an IEEE specification for 100-Mbps Token Ring and Ethernet implementations over 4-pair UTP. The MAC layer is not compatible with the IEEE 802.3 MAC layer. 100VG-AnyLAN was developed by Hewlett-Packard (HP) to support newer time-sensitive applications, such as multimedia. …


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5 Regulatory issues - Bundling and unbundling - Situation after unbundling, benefits and problems - Frequency availabilities (and clashes) Cost and ease of use

5.1 Cable Modem Regulatory Aspects

5.1.1 Cable Open Access The cable open access concept is the result of the opening of cable modem networks to multiple ISPs. ISPs in U.S. created a coalition named OpenNET that lobbied for the opening of cable networks. Regulatory measures followed in early 1999 in the U.S., and in Canada in October 1999. The U.S. Federal Communications Commission (FCC) and the Federal Trade Commission (FTC), have specially established a series of principles for cable open access in relation to the merger of America Online Inc. and Time Warner in January 2001:

• MSOs would have to offer at least one independent ISP service and a minimum of two other non-affiliated ISPs within 90 days of service launch, with the obligation not to favor its ISP affiliated offerings to prospective customers. No affiliate contracts should prevent ISPs from disclosing terms of their agreements to the FCC.

• MSOs were prohibited from interfering with content carried by ISPs. Each ISP is to be able to control the content on its subscribers' first screen and should not be required to include any content as a condition of obtaining access to the MSO’s cable systems.

• All ISPs should benefit, on the same terms, of different quality-of-service (QoS) levels, network monitoring or subscriber accounting data for ISPs implemented by the cable operator.

• Agreements among MSOs for service carriage, should allow all independent ISPs to benefit from special rates and terms in the agreement.

MSOs cannot force customers to go through an affiliated ISP to reach the ISP of their choice. ISPs may have direct billing arrangements with their customers. The concept of cable open access has first led cable network operators to fear being assimilated to common-carriers for Internet services. They could potentially be positioned as providers of network bandwidth, and see it limiting their capacity to generate return on their infrastructure investments.


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In the U.S., regulators encouraged market-driven cable access implementations rather than pure open access, allowing for managed access models. On the contrary, in Canada MSOs were required to file firm tariffs to provide competitive ISPs with wholesale access to their cable facilities.

5.1.2 Cable open access - Business considerations In the current cable modem service provision models, operators typically market a flat-rate package that includes broadband network and Internet access, with the cost of the cable modem integrated into the package or separately charged as a modem rental or purchase fee. The total cost to the consumer (including modem rental) typically runs from $40 to $45 monthly, or between $30 and $35 monthly with consumer-owned modem. MSOs typically pay out about 30 percent of the service fees to ISPs, meaning that the net broadband loop charge can range from $20 to $28 and the ISP revenue from $9 to $12 per month. In a managed access environment, ISPs are likely to opt for directly billing subscribers. This shall lower MSOs' cable modem service revenue by nearly a third. The marketplace measures MSOs’ performance in terms of revenue-per-subscriber which shall oblige cable operators to find alternative ways to leverage gross subscriber revenues. Options lie in using the marketing power of ISPs to increase the cable modem customer base, or generating incremental revenue from retail and wholesale value-added services, such as through quality-of-service (QoS) and streaming media applications.

5.1.3 Cable open access - Technical Implementation

The desire to deliver value-added services to multi-ISP access is leading MSOs to adopt IP-centric solutions, called policy-based routing (PBR), instead of point-to-point protocols (over ATM and Ethernet) and layer 2 tunneling protocol (L2TP) used by DSL providers. Despite widely used in the DSL field of applications, PPP and L2TP present a couple drawbacks for cable operators: Client software is required on subscribers’ PC and the tunneling implies online sessions with logon procedures eliminating the "always on" connectivity concept. In addition, service providers have to provide technical support for the software, a costly requirement. Tunneling adds overhead to packets and reduces available network capacity. The tunneled traffic is routed transparently point-to-point, preventing the cable operator to offer application-specific enhancements. The policy-based routing (PBR) technology is still maturing, but there seem to be consensus among cable operators to wait due to the prospective better long-term business propositions.


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5.1.4 Policy-Based Routing Policy-based routing (PBR) involves implementing policies and rules in IP routers or switches to manage network traffic and services. Considering multiple ISPs serviced by the same cable network, routing policies should allow the router to send the traffic to the ISP backbone that is associated with the subscriber's source IP address, and on the basis of the right policy applied, be able to check if the customer's request could be fulfilled through a local content caching server to reduce backbone congestion for the ISP. To satisfy different classes of services for ISPs and customer needs, other policies must be implemented to allow packet prioritization, e.g. for IP telephony, for audio and video streaming. QoS treatment is already supported through DOCSIS 1.1 for the cable modem access network, and on the core network with standard IP techniques like multiprotocol label switching (MPLS) and Diff-Serv, or ATM virtual circuits (VCs). High-performance routers are required for PBR, to handle the routing and switching load based on complex policies consuming more processing power and memory than traditional destination-only routing, while ensuring scalability. To handle increased numbers of cable modem subscribers without service degradation, PBR functionality must be brought to the network edge, preferably in an integrated DOCSIS CMTS and IP switch/routers.

5.1.5 IP addressing and integration issues On cable networks servicing a single ISP, cable modems are allocated a private IP address via a dynamic host configuration protocol (DHCP) server, and customer PCs receive a public IP address, also via DHCP. In a PBR-based multi-ISP environment, the cable operator directs traffic to ISPs based on source routing (subscriber PC's public IP address). Therefore, ISPs will have to provide MSOs with large blocks of IP addresses and MSOs shall configure their DHCP servers to bind the media access control (MAC) address of the subscriber’s PCs to the IP address block of the appropriate ISP. Besides the above technical issues on routing policies and IP address management, several other subjects should be considered for the cable open access implementation. It should cover among others, topics related to the negotiations for the integration of broadband services and operating relationships, automation of cable modem activation and the responsibility for providing telephone technical support when multiple ISPs are concerned,


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6 Main drivers in the evolution of Access networks - Industries - Standards - Regulators - Users - Policy makers - Cost - Ease of use


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7 Market overview 7.1 Introduction - Examples of European countries - Trends

7.2 Cable Modem

7.2.1 Cable Modem Service Costs There is a growing tendency, in particular in North America, for cable operators to package Internet access and high-speed data services with the basic cable TV service. Prices are typically in the range of $40 to $60 per month for an Internet service package that includes software, unlimited Internet access, specialized content and rental of a cable modem. Kinetic Strategies Inc. estimated that cable operators were commercially ready to offer high-speed Internet services to more than 65 million homes in North America, by March 2001, and had attracted 5.5 million paying subscribers. The availability of a high-quality two-way HFC network is a key factor in the deployment of two-way cable data services. Some Multiple System Operators (MSO) have been investing about $200 - $250 per home to make two-way HFC upgrades and deploy broadband cable data services.

7.2.2 Cable Modem Market Stats & Projections Kinetic Strategies Inc. estimated 9.3 million residential broadband Internet subscribers as of 1st of June, 2001 in North America (US and Canada), representing 8.2% household penetration. Among these figures, 6.4 million are cable modem customers, representing 70% of the market, and 2.9 million are DSL lines. By end of 2004, Kinetic Strategies estimates the North American market for standards-based cable modem products and services to represent more than 20 million customers. The sales of DOCSIS cable modems, CMTS and IP switching equipment should exceed $6 billion. Cable modem service revenue is projected to exceed $20 billion. Additional information and pricing details for the new DOCSIS Infrastructure Deployment Forecast are available at http://www.kineticstrategies.com/docsis/.


http://www.kineticstrategies.com/docsis/

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7.3 Fast Ethernet Fast Ethernet is mainly used by corporate users. It is still proposed as Network Access Technology for home users. Financial aspects are based on 3 criteria: Backbone infrastructure Network equipment End-user infrastructure

7.3.1 Backbone infrastructure As the technology has small distance limits, the provider needs to set-up an infrastructure in each set of building. This implies quite big investment for the first infrastructure installation.

7.3.2 Network Equipment As it is the most used network technology, Fast Ethernet equipment remains at quite low price compare to any other equipment. It is also easy to install and manage.

• Fast Ethernet cards 50$ to 100 $ • Fast Ethernet hub 8 port 100$ to 200$

7.3.3 End-user infrastructure A special cabling infrastructure may need to be implemented in the end-user office/home, that implies additional costs.


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8 Evolution scenarios 8.1 Introduction - Copper - Wireless - Optical

8.2 Cable IP Telephony

8.2.1 Introduction Economic and operational barriers, despite the commercial attractiveness and the existence of reliable technical solutions, discouraged the offer of residential telephone services over HFC cable networks. With the emergence of IP networks and new solutions for the handling of voice traffic, MSOs benefit now from technologies that allow them to use their high-speed data networks to support packet telephone services without having to deploy standalone parallel HFC telephony equipment. By creating integrated multi-service communications platforms they also benefit from lower cost structures than existing circuit-switched telephone networks, and can plan on discounted pricing without sacrificing margins. In addition, IP networks should allow MSOs to offer other value-added features, such as integrated voice mail and e-mail messaging, and the provisioning of additional phone lines without rewiring the residence. But, cable operators must overcome a number of other problems such as the support of IP telephony over the first generation DOCSIS cable modems. In addition, to handle customer provisioning, management and billing, cable IP telephony operations support systems are required, and interconnection standards among MSOs need to be put in place to effectively regulate the sharing of packet telephony traffic.

8.2.2 Packet Telephony Overview

Circuit switched telephone networks establish a dedicated circuit between two end points for the duration of a call, or allocate a 64Kbps circuit over digital telecommunication networks. With dedicated circuit switching transmission delays (latency) are maintained within certain limits and guarantee the telephone call quality. On the contrary, in connectionless packet data networks, circuits are shared and only used when data in packet form is sent or received. Using compression algorithms, telephone calls can be supported through packet rate formats of 8 Kbps that offer increased bandwidth efficiencies.


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Shared data networks are subject to delays that can affect call quality, unless strict QoS and prioritization schemes are used to ensure that voice packets reach their destination within acceptable delays. Otherwise, jitter can occur, causing distortion or unacceptable pauses during a call. Cable operators seem to tend to adopt the Media Gateway Control Protocol (MGCP) for call set-up and management to route IP voice traffic. Several compression and decompression algorithms (codecs) ranging from 8 Kbps (G.729) to 64 Kbps (G.711) are supported.

8.2.3 The DOCSIS 1.1 standard The DOCSIS 1.0 standard was designed as a cheap consumer Web-surfing platform, but does not provide all of the QoS and latency controls required to offer toll-quality IP telephony services. This has driven the necessity to release a third generation of the DOCSIS standard, DOCSIS 1.1, that incorporates three features to support toll-quality telephone calls: upstream packet fragmentation and reassembly, support of a national clock and an advanced isochronous scheduling system. Packet fragmentation is required to avoid upstream congestion impacting the call quality. The largest Ethernet packet size is 1500 bytes, implying about 15 milliseconds to send it upstream over a 768-Kbps cable modem. Such delay would strain the acceptable delay limits for a voice call. Using fragmentation techniques, large data packets are broken into smaller ones to prevent unacceptable transmission delays. A national clock is necessary to properly synchronize transmissions between cable modems on the network. A high-quality isochronous scheduler to headend-based DOCSIS cable modem termination system (CMTS) equipment is necessary because the DOCSIS 1.0 standard was designed as a consumer Internet access platform with system latency running in the 50 to 70 millisecond range. To support packet telephony, CMTS must offer an isochronous scheduling solution closer to a two-milliseconds time scale.

8.2.4 PacketCable The PacketCable project was created to identify existing interface protocols, and to define new protocols that together would support the delivery of real-time multimedia services over the DOCSIS 1.1 cable modem architecture. PacketCable networks use IP technology as the basis to enable cable operators to deliver data and voice traffic efficiently and economically using a single high-speed, QoS-enabled broadband architecture. The intended architecture needs to support several end-to-end functions, including signaling for services, media transport at variable QoS levels, security, provisioning of the client device, billing, and other network management functions. Together,


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PacketCable and DOCSIS 1.1 provide an integrated solution that enables high-quality voice and data services to be delivered over the same two-way HFC cable plant. The basic PacketCable architecture defines a “SoftSwitch” architecture for IP telephony. The core set of PacketCable specifications describe how the basic functions typically consolidated on a expensive Class 5 central office switch can be executed by several general-purpose servers, which leads to a low-cost, highly flexible, scalable, distributed architecture. This architecture can also be extended to support advanced real-time multimedia services. Several cable operators are currently conducting field trials using products based on PacketCable specifications.

PacketCable Reference Architecture by CableLabs® The initial set of PacketCable specifications was approved in February 2001 and was submitted to the ITU-T as a starting point for international standardization. They are referred to as “IPCablecom” in the ITU-T. The majority of the initial set of standards was approved by the ITU-T in March 2001.

8.2.5 PacketCable Products

In the PacketCable architecture proposed by the Cable TV Laboratories Inc., a range of DOCSIS 1.1 based client devices will support IP telephone connections. It includes cable modems, digital set-tops, media terminal adapters (MTAs), and standalone devices linking telephone handsets to the cable data network. A single DOCSIS CMTS can serve all these devices within the same cable spectrum. Vendors expect that the addition of IP telephony support will only increase the cost of a DOCSIS 1.1 cable modem by 20 to 30 percent. An integrated cable modem and PacketCable


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MTA could be priced as low as $250. To offer a lifeline IP telephony service, a battery pack is needed, which for 8 hours of stand-by power it is estimated to add $40-$50 to the price of a cable IP telephony device. Over time, consumer electronics companies are likely to offer cable IP telephony products in a variety of configurations, such as cordless telephone system base stations. The cable industry is pursuing standardization of VoIP services in order to attain worldwide interoperability of services and equipment, vendor independence, ease of interconnection with other operators, and reduced cost through economies of scale.

8.2.5.1 End-to-end issues and service strategies Cable operators face several challenges to support end-to-end IP telephony that go from building DOCSIS 1.1 headend and client products with IP telephony support, efficiently provisioning and managing the devices on the network, engineering disparate local cable data systems and backbone networks to offer quality IP telephony. Initially, it is expected that most cable operators shall favor the deployment of IP telephony simply as a local-loop bypass service. In this scenario, voice packets are directly transferred from the CMTS to an IP telephony gateway that routes calls to PSTN. Subsequently, MSOs shall target at offering long-distance IP telephony over their packet backbone networks, by carrying calls long distance at very low cost and without traversing standard local or interchange telephone company networks. Adequate options should be evaluated and interconnection arrangements studied. Globally, cable operators shall have different IP telephony service strategies, ranging from the offer of competitive lifeline phone service, the selling of second phone lines, or a packaged remote LAN and PBX access for corporate telecommuters. At the same time, with IP telephony functions supported by different devices, such as set-top devices and cable modems, new service options are possible as using an interactive set-top to offer directory services, caller ID, and other features on the TV. In general it is possible to admit that broadband packet networks will operate with quite different economic assumptions than PSTN, and result in different pricing and packaging models.


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9 Future possible directions 9.1 Optical Ethernet Some carriers are already deploying Gigabit Optical Ethernet services today. They may limit their customers to a few megabits per second, but the links are gigabit-capable; and someday the fees for gigabit-scale Ethernet services will be affordable. Then, even a 10-Gigabit–Ethernet transport will be inadequate. 40-Gigabit speeds (SONET OC–768) have already been demonstrated, so that is a possible Ethernet target. In the meantime, the protocols and techniques for bandwidth sharing over parallel links exist, work well, and are used in thousands of sites. It is a simple step to run parallel Optical Ethernet trunks, each on a separate wavelength, all multiplexed over a single fiber pair using DWDM technology. In this way, a point-to-point Ethernet link could have scores of 10-Gigabit channels, with an aggregate Ethernet bandwidth of perhaps 400 Gigabits. Using recently announced DWDM capacity of 160 wavelengths, 1600-Gigabit links could be implemented. So in a sense, Terabit Ethernet is already available. Of course, this kind of network requires very large Ethernet switches at the ends of that fiber. The limits on optical Ethernet bandwidth may just be the limits of fiber optic bandwidth, perhaps 25 Terabits per second for the available spectrum on today’s fiber, which is still well beyond the capabilities of today’s lasers and electronics. Still, extrapolating from recent trends gets us to that level in only 5 or 10 years.

9.2 LMDS Overall, LMDS compares favorably with competing options on both a basis of performance and cost, but it lacks the wide support and financial backing which other platforms possess. This could prove to be significant. Industry support has flooded behind cable modem and ADSL technologies. Low cost chipsets and ASICs are available for platforms, and the technologies' boast an impressive list of supporters. Members of the computing industry seem to be supporting ADSL, and to a lesser extent cable modems, as a means of delivering multimedia content to homes and businesses. This industry has a lot to gain from the success of broadband delivery, and logic suggests, that its members will go to great lengths to bring the most probable broadband technologies to the mass market. ADSL seems to be that technology. LMDS is not as fortunate. Only a few companies have publicly committed to supporting the platform and those, which have, lack the distribution, name-brand awareness, and financing which supporters of ASDL and cable modems possess. The difference is likely to result in LMDS CPE that cost more than and lacks the distribution of cable and ADSL modems. In addition, there will be lower visibility for LMDS. Time could also be an issue. If cable modem


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and ADSL services become widely accessible within the next two years, then deployment of LMDS could prove unattractive in areas that already possess other alternatives. The future of LMDS is unknown. There are a number of variables that could drastically alter the market and the fortunes of LMDS providers. ADSL and cable modem deployment could lag considerably behind expectations, and satellite and many LMDS operators may not even build out their networks. However, developments in the market today suggest that leading LMDS auction winners will deploy networks, and that these service providers will concentrate their efforts on business and well-to-do residential customers. The high-cost of CPE will preclude deployment to other residential areas, at least initially. List of standards

General References

Recommendation ITU-T G.902 "Framework recommendation on functional access networks".

Recommendation ITU-T G.652 ”Characteristics of a single-mode optical based cable”.

Recommendation ITU-T G.671 ”Transmission characteristics of passive optical components”.

Recommendation ITU-T G.661 ”Definition and test method for the relevant generic parameters of optical based amplifiers”.

Recommendation ITU-T G.662 ”Generic characteristics of optical based amplifiers”.

Recommendation ITU-T G.663 ”Application related aspects of optical based amplifiers devices and sub-systems”.

Recommendation ITU-T I.41 ”Overview of recommendations on Layer 1 for ISDN and B-ISDN customer access".

Recommendation ITU-T Q.512 ”Digital exchange interfaces for subscriber loop".

Recommendation ITU-T G.964 ”V interfaces at the digital local exchange -V5.1 interface for the support of access network".

Recommendation ITU-T G.965 ”V interfaces at the digital local exchange -V5.2 interface for the support of access network".

Recommendation ITU-T I.430. ”Basic rate user-network interface-Layer 1 specification".

Recommendation ITU-T I.431. ”Primary rate user-network interface-Layer 1 specification".

ETR 326: "Transmission and Multiplexing (TM); B ISDN access".

ETR 326 2 edition: "Transmission and Multiplexing (TM); Broadband access".

ETR 248: "Transmission and Multiplexing (TM); Use of single mode based in the access network".


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prETS 300 681: "Transmission and Multiplexing (TM); Optical distribution network for Optical access network".

ETS 300 463: "Transmission and Multiplexing (TM); Requirements of Passive Optical Access Network to provide services up to 2 Mbit/s bearer capacity".

ETS 300 233: "Integrated Services Digital Network (ISDN); Access digital section for ISDN primary rate".

ETR 328: "Transmission and Multiplexing (TM); Study and investigation of Asymmetrical Digital Subscriber Lines (ADSL)'".

DAVIC 1.0 Part 04: "Delivery System Architecture and Interfaces".

Bellcore FA-NWT-001307, ”Framework Generic Requirements for Asymmetric Digital Subscriber Lines”, Issue 1, December 1992.

T1E1.4/92-002R1 A technical Report on High-bit-rate Digital Subscriber Lines (HDSL), February 14,1992.

prETR/-152 Edition 3 ”Transmission and Multiplexing (TM) High bit-rate digital subscriber line (HDSL) on metallic local lines HDSL core specification and applications for 2048 kbit/s based access digital sections”, July 1996.

DTR/TM-03050 ”Transmission and Multiplexing: Asymmetric Digital Subscriber Line, Version 3”, February 1996.

Draft DTS/TM-06003-1 ”Very high speed Digital Subscriber Line (VDSL) Part1: Functional Requirements”, April 1997.

Proc. "Full services access networks conference", London, 20 June 1996.

Session "Full services access networks", in Proc. VIIIth Workshop on Optical/Hybrid Access Networks, Atlanta (GA), 2-5 March 1997.

W. Warzanskyj, U. Ferrero, "Access network evolution in Europe: a view from EURESCOM", in Proc. ECOC 1994, Firenze, 25-29 September 1994.

U. Ferrero, "Broadband optical access network: cooperative work among European PNOs", in Proc. of ECOC 1996, Oslo, 15-19 September 1996.

U. Ferrero, M. Mavis, W. Warzanskyj, "The challenge of the broadband access: PNOs cooperation in Europe", in Proc. VIII IEEE Workshop on Optical and Hybrid Access Networks, Atlanta, GA, 2-5 March 1997.

ATM Forum, ”RBB Baseline Document Draft”, ver. 1.02, Chicago, April 1997.


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List of xDSL- standards

ANSI Committee T1 Technical Report No. 28 (February 1994): "A Technical Report on High Bit-Rate Digital Subscriber Lines (HDSL)".

ANSI T1.413 - issue 2: "Draft Proposed Revision of ANSI T1.413-1995 - Interface Between Networks and Customer Installation - Asymmetric Digital Subscriber Line (ADSL) Metallic Interface".

ANSI T1E1/97 - 104R2a: "Draft Proposed American National Standard - Interface Between Networks and Customer Installation - Rate Adaptive Digital Subscriber Line (RADSL) Metallic Interface".

ADSL Forum Reference model, TR-001 ”ADSL Forum System Reference Model”.

ADSL Forum Reference model, TR-002 ”ATM over ADSL Recommendations”.

ADSL Forum Reference model, TR-003 ”Framing and Encapsulation Standards for ADSL: Packet Mode”

ADSL Forum Reference model, TR-004 ”Network migration”

DAVIC 1.3 part 08: "Lower layer protocols and physical interfaces".

ETSI EG 200 306 v1.2.1 (1998-03) ”Transmission and Multiplexing ( TM ); Access networks for residential customers

ETSI TS 101 135 V1.4.1: "Transmission and Multiplexing (TM); High bit-rate Digital Subscriber Line (HDSL) transmission system on metallic local lines; HDSL core specification and applications for 2’048 kbit/s based access digital sections".

ETSI ETR 328: "Transmission and Multiplexing (TM); Asymmetric Digital Subscriber Line (ADSL); Requirements and performance".

ETSI DTS/TM-06003-1: "Transmission and Multiplexing (TM); Very High Speed Subscriber Lines (VDSL); part 1-functional requirements".

Draft ITU-T Recommendation G.hdsl: "High bit rate Digital Subscriber Line (HDSL) transmission system on metallic local lines; HDSL core specification and applications for 2 048 kbit/s based access digital sections".

List of standards and publications for coaxial access based networks

DAVIC 1.0 Part 04: "Delivery System Architecture and Interfaces".

DAVIC 1.0 Part 08: "Lower layer protocols and physical interfaces".

IEEE 802.14-94/002R3: "IEEE P 802.14 Cable-TV functional requirements and evaluation criteria".


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IEEE 802.14-Draft 2 Revision 2: "Cable-TV Access Method and Physical Layer Specification”

ITU-T Recommendation J.1 (ITU-T SG9): "Terminology for new services in television and sound program transmission".

J.83 ITU-T Recommendation J.83 (ITU-T SG9): "Digital Multi-programme systems for television, sound and data services for cable distribution

ITU-T Recommendation J.84 (ITU-T SG9): "Distribution of digital multi-programme signals for television, sound and data services through SMATV networks".

ITU Recommendation J.112 (ITU-T SG9): ”Transmission systems for interactive cable television systems”

ETS 300 429 (JTC, 94/12): ”Digital Broadcasting Systems for Television, Sound and Data Services; Framing structure, channel coding and modulation for cable systems".

EN 300 429 Ver. 1.2.1, (JTC 97/12): ”Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems".

ETS 300 421 (JTC, 94/12): "Digital Broadcasting Systems for Television, Sound and Data Services; Framing structure, channel coding and modulation for 11/12 GHz satellite services".

EN 300 421 (JTC, 97/08): "Digital Broadcasting Systems for Television, Sound and Data Services; Framing structure, channel coding and modulation for 11/12 GHz satellite services".

ETS 300 473 (JTC, 97/09): "Digital Broadcasting Systems for Television, Sound and Data Services; Satellite Master Antenna Television (SMATV) distribution systems".

EN 300 473, (JTC, 97/08): ”Digital Video Broadcasting DVB Satellite Master Antenna Television (SMATV) distribution systems”

ETS 300 744 (JTC, 97/03): "Digital Broadcasting Systems for Television, Sound and Data Services; Framing Structure, Channel Coding and Modulation for Digital Terrestrial Television". (Based on DVB Technical Module TM1 354).

EN 300 744 Ver. 1.1.2 (JTC, 97/08): "Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television ”

Final Draft prETS 300 800 (JTC, 98/01): "Digital Video Broadcasting (DVB); Interaction channel for Cable TV distribution systems (CATV)".

TR 101 196 (JTC, 97/12): "Digital Video Broadcasting (DVB); Interaction channel for Cable TV distribution systems (CATV)”seems a guideline for the use of ETS 300 800.

ETS 300 801 (JTC, 97/08): "Digital Video Broadcasting (DVB); Interaction channel through Public Switched Telecommunications Network (PSTN/ISDN)".

ETS 300 802 (JTC, 97/11): "Digital Video Broadcasting (DVB);Interaction channel for Cable TV distribution systems (CATV)


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ETS 300 813 (JTC, 97/12): "Digital Video Broadcasting (DVB); DVB interfaces to Plesiochronous Digital Hierarchy (PDH) networks

ETS 300 814 (JTC, 96/12, 98/03): "Digital Video Broadcasting (DVB); DVB interfaces to Synchronous Digital Hierarchy (SDH) networks"

ETS 300 815 (JTC, 97/12): "Digital Video Broadcasting (DVB); DVB interfaces to Asynchronous Transfer Mode (ATM) networks. Draft European Telecommunication Standard

prEN 301 192 Ed.1.1.1 (JTC, 97/12): "Digital Video Broadcasting (DVB); DVB specification for data broadcasting”

TR 101 190 (JTC,97/12): ”DVB; Implementation guidelines for DVB terrestrial services; Transmission aspects”

TR 101 196 (JTC, 97/12): "Digital Video Broadcasting (DVB);Interaction channel for Cable TV distribution systems (CATV), Guidelines for the use of ETS 300 800

TR 101 200 (JTC, 97/08): "Digital Video Broadcasting (DVB); A guideline for the use of DVB specifications and standards”.

TR 101 201 (JTC, 97/10): "Digital Video Broadcasting (DVB) Interaction channel for SMATV distribution systems; Guidelines for versions based on satellite and coaxial sections".”.

ETSI NA8 DTR/NA-080201: ”Interworking with PSTN, N-ISDN, Internet and Digital Mobile Networks”

ETSI NA8 DTR/NA-080202: ”Interworking with B-ISDN”

EN 50083-1: "Cabled distribution systems for television and sound signals - Part 1: Safety requirements".

EN 50083-2: "Cabled distribution systems for television and sound signals - Part 2: Electromagnetic compatibility for equipment".

EN 50083-3: "Cabled distribution systems for television and sound signals - Part 3: Active coaxial wideband distribution equipment".

EN 50083-4: "Cabled distribution systems for television and sound signals - Part 4: Passive coaxial wideband distribution equipment".

EN 50083-5: "Cabled distribution systems for television and sound signals - Part 5: Headend equipment".

EN 50083-6: "Cabled distribution systems for television and sound signals - Part 6: Optical equipment".

EN 50083-7: "Cabled distribution systems for television and sound signals - Part 7: System performance".


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EN 50083-8: "Cabled distribution systems for television and sound signals - Part 8: Electromagnetic compatibility for equipment".

EN 50083-9: "Cabled distribution systems for television and sound signals - Part 9: Interfaces for CATV/SMATV head-end and similar professional equipment".

EN 50083-10: "Cabled distribution systems for television and sound signals - Part 10: System performance and associated methods of measurement for return channel transmission in multimedia applications".

EN 50083-11: "Cabled distribution systems for television and sound signals - Part 11: DVB interaction channel (DVB-RC-126)".

EN 50117: ”Coaxial cables used in cabled distribution networks”

EN 50201: "Interfaces for digital video broadcast integrated receiver decoder (DVB-IRD)".

EN 50221: "Common interface specification for conditional access and other digital video broadcasting decoder applications".

EN 50256: "Characteristics of DVB receivers”.

CENELEC TC 205: CLC/Technical Committee 205(SEC)175A: "HBES report no. 4; Applications and requirements - Class 2 and 3


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