CAPANINA Deliverable Report D01

FP6-IST-2003-506745 CAPANINA Deliverable Number D01

Applications and Services for Broadband HAP Delivery Including implications on network functionality and interfaces, e.g. for third-party network providers Document Number

CAP-D01-WP11-BT-PUB-01

Contractual Date of Delivery to the CEC

1 Feb 2004

Actual Date of Delivery to the CEC

29 Jan 2004

Author(s):

Ken Fowler, Mike Fitch, Milan Lalovic (BT),Jose A.Delgado-Penin (UPC), Csaba Kiraly, Tien V. Do, Papp Denes (BUTE)

Participant(s) (Partner short names)

BT, UPC, BUTE

Editor (Internal reviewer)

Tim Tozer (UOY)

Workpackage:

WP1.1

Estimated person months

3

Security (PUBlic, CONfidential, REStricted)

PUBlic

Nature

R – Report

CEC Version

1.1

Total number of pages (including cover):

82

st

th

Abstract:

Deliverable D01 is an output document from Workpackage WP1.1, Applications and Services Development. The objectives of WP1.1 are to evaluate suitable existing applications and to develop new mobile and fixed applications that may be profitably carried on Broadband HAPs. D01 provides candidate applications and services for broadband HAPs delivery, including implications on network functionality and interfaces, e.g. for third party service providers. The report also identifies candidate applications to be tested as part of a trials programme, and so is an input document to WP4 (Systems Testbed). Keywords: Broadband services and applications, HAP, HAPs, High Altitude Platforms, Business models,


Applications and Services for Broadband HAP Delivery

DOCUMENT HISTORY

Date

Revision

29 Jan 03

01

Comment First issue

Editor Ken Fowler

Affiliation BT

Document Approval (CEC Deliverables only)

Date of approval

Revision

28 Jan 04

01

Editor (Internal reviewer)

Tim Tozer

UOY

30 Jan 04

01

On behalf of Scientific Board

David Grace

UOY

29th Jan 2004

Role of approver

Approver

FP6-IST-2003-506745-CAPANINA

Affiliation

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EXECUTIVE SUMMARY Overview Broadband Europe is making progress and the headlines are positive. Cable and DSL (Digital Subscriber Line) are becoming available to increasing numbers of citizens and the advantages of broadband, especially to SMEs (Small to Medium Enterprises), are becoming obvious. However, we can do more. There is a digital divide in Europe, and indeed globally, where citizens in rural communities are disadvantaged through not having access to broadband. In a global economy, investment and jobs flow more easily and rapidly to areas where the communications infrastructure can support the business requirement. Furthermore, the bandwidths available from DSL are limited, typically to around 512 kbit/s downstream. New generation broadband, probably led initially by VDSL (Very high data rate DSL) and eventually fibre to the home, will offer much higher bandwidths at consumer prices. This will lead to a new generation of broadband services and applications that will exacerbate the digital divide still further. A range of alternative technologies can be used to bridge this digital divide, for example satellite, fixed wireless access, UMTS (Universal Mobile Telecommunications System), High Altitude Platforms (HAPs), etc. The FP6 CAPANINA project is specifically about communications from HAPs delivering broadband to a community. Target communities are those in rural areas affected by the digital divide, but HAPs are also useful for other applications, for example broadband to mobiles, e.g. W-LANs on trains, rapid communications to disaster sites, etc. But the availability of broadband alone is not enough. Without compelling content, broadband will not achieve the penetration levels that will guarantee success and drive the broadband revolution. A requirement is an understanding of the candidate applications and services for broadband HAPs delivery, and this is the subject of this report. To date, broadband has been successful in the business marketplace. There is real momentum in by SMEs in embracing this technology, which means the digital divide is even more serious for those in rural communities where cable / DSL has not yet reached. Services and applications such as broadband Internet / Intranet, web hosting, file transfer, etc., all at affordable prices, have shown real dividend to business. Adoption of broadband by consumers has been less successful (except for the special case of TV). For example, DSL is available to around 85% of UK households but adoption in is only around 6%, this in spite of competition amongst service providers and wholesale prices in the region of €20 per month for always-on access. Here, compelling content is essential for success. Broadband enables the faster delivery of services and applications that can be delivered (with an inferior QoS) via narrow-band, but is evolving with the development of new content that exploits the unique characteristics of broadband. As the adoption of broadband continues to increase, we will see a range of applications and services that will combine together to encourage mass market adoption of broadband, and provide the necessary incentive for users to migrate to the future higher bandwidth networks. This again, is an opportunity for HAPs.

Applications and Services for Business Broadband has the potential to transform business, enabling companies to be more productive, innovative and competitive. SMEs in particular are able to benefit, via cable and DSL, from range of services and applications that was previously unaffordable through leased lines. These include faster access to emails, web hosting and always-on access. Teleworkers and remote offices can enjoy faster access to company Intranets, faster file up-loads and down-loads. As business learns to exploit broadband, many new commercial opportunities can be developed, for example a greater use of video 29th Jan 2004


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conferencing, including desktop applications. It is to be expected that pressure from suppliers and customers will eventually make broadband essential for all businesses.

Applications and Services for mass market Consumers Broadband Internet and the ability to up-load, and especially download date files (music, photographs, video clips, etc), are the key broadband drivers for consumers at the moment. Entertainment is a also major mass market opportunity, for example live TV, video streaming and video on demand.

Opportunities for HAPs HAPs can carry all of the broadband services and applications listed above. HAPs are probably best used in the access network to connect a user to a core network and thence to the desired application or service. However, HAPs can also be used to link users within a private networks, or they can be used to provide point to point (bearer) links. In all of these respects the use of HAPs is analogous to the that of satellite and VSATs (Very Small Antenna Terminals). Satellite can offer a broadband solution, but it is better suited to broadcast applications. HAPs, with its superior link budget, small cellular structure and frequency re-use, is better positioned for cost competitive point to point links. Satellite is better positioned for wide distribution TV broadcast applications although HAPs, like terrestrial radio, may be better suited to local or regional TV distribution. Only radio can support mobile applications; HAPs have a part to play here with the potential to provide broadband communications to vehicles and trains. Where there is direct competition with cable and DSL, HAPs will need to be cost competitive. The best opportunity for HAPs is therefore in rural locations where DSL and cable do not exist, or to support applications requiring higher bandwidths than these networks can provide. Video on demand, video streaming and community TV broadcasts could be viable applications for HAPs.

Trials The CAPANINA project envisages a series of trials to test the viability of certain applications via HAPs. Broadband Intranet and video streaming are suggested as viable applications for these tests.

.

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TABLE OF CONTENTS

1.

INTRODUCTION........................................................................................................... 10

2.

BROADBAND OVERVIEW ........................................................................................... 11

2.1 2.2 2.3

3.

FUTURE GENERATION BROADBAND SERVICES AND APPLICATIONS ................. 15

3.1 3.2 3.3 3.4

4.

Broadband Definition ................................................................................................................ 11 Advantages of Broadband ........................................................................................................ 12 Broadband Services Classification ........................................................................................... 13

Broadband Market Growth ........................................................................................................ 16 Future Multimode Broadband Systems..................................................................................... 17 Future Fixed and Mobile Broadband Services .......................................................................... 19 Future HAP Network Possibilities ............................................................................................. 20 3.4.1 Impact of Ka/V-band propagation characteristics on services and applications................. 21 3.4.2 Fade countermeasures techniques and the impact on applications................................... 24 3.4.3 Security issues .................................................................................................................... 26

OPERATING SCENARIOS ........................................................................................... 27

4.1

HAPs Network Scenarios.......................................................................................................... 27 4.1.1 User scenarios .................................................................................................................... 27 4.1.1.1 At home 28 4.1.1.2 In the office ............................................................................................................................... 28 4.1.1.3 Remote offices .......................................................................................................................... 28 4.1.1.4 Teleworkers............................................................................................................................... 29 4.1.1.5 Hospitals 29 4.1.1.6 Schools, Colleges and Universities ........................................................................................... 29 4.1.1.7 Government Departments.......................................................................................................... 29 4.1.2 Summary of access network requirements ........................................................................ 29 4.2 Topology ................................................................................................................................... 31 4.2.1 HAPs topology .................................................................................................................... 32 4.2.1.1 Transparent transponder(s), single beam................................................................................... 32 4.2.1.2 Single HAP, multiple beam antenna, without on board processing ........................................... 33 4.2.1.3 Single HAP, multiple beam antenna with on-board processing (on-board modulation and demodulation). .......................................................................................................................... 34 4.2.1.4 Multiple interconnected HAPs .................................................................................................. 35 4.2.2 Ground topology ................................................................................................................. 36 4.2.2.1 Point to point private circuits .................................................................................................... 36 4.2.2.2 Broadcast 36 4.2.2.3 Point to Multipoint Service ....................................................................................................... 37 4.2.2.4 Multiple access, Star and Mesh Configurations ........................................................................ 38 4.2.2.5 Ground Terminal Configuration ................................................................................................ 39

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5.


POTENTIAL APPLICATIONS AND SERVICES FOR HAPS ........................................ 41

5.1 5.2 5.3

Traffic Classes .......................................................................................................................... 41 HAP Scenarios of Operation and Services ............................................................................... 42 Broadband Internet ................................................................................................................... 43 5.3.1 Broadband Internet for Domestic Users ............................................................................. 44 5.3.2 Broadband Internet for SME and SOHO ............................................................................ 44 5.4 Broadband Access to Company Intranet .................................................................................. 44 5.5 Videoconferencing .................................................................................................................... 45 5.6 Entertainment............................................................................................................................ 45 5.6.1 TV and Radio ...................................................................................................................... 45 5.6.2 Video on Demand ............................................................................................................... 46 5.6.3 Gaming ............................................................................................................................... 46 5.7 Distance Learning ..................................................................................................................... 46 5.8 Telemedicine (for teaching and assistance) ............................................................................. 47 5.9 Disaster site communications and services .............................................................................. 48 5.10 Communications at Temporary Venues (Special Events, Olympics, etc.)................................ 48 5.11 Overlay of Terrestrial Data Links for Resilience (link failure recovery) ..................................... 48 5.12 Wireless LAN Hot Spot Backhaul ............................................................................................. 49 5.13 Wireless LAN on Trains and Coaches (backhaul) .................................................................... 49 5.14 UMTS HAP Base Station Provision .......................................................................................... 49 5.15 Broadcast Based Broadband (B3) ............................................................................................ 50 5.16 Military Applications .................................................................................................................. 50 5.17 Third World Applications ........................................................................................................... 50

6.

ISSUES WITH THIRD PARTY APPLICATIONS AND SERVICE PROVIDERS ............ 51

6.1 6.2 6.3

Roles, Players and the Value Chain Framework ...................................................................... 51 Reference Frameworks ............................................................................................................ 52 Signalling Protocol .................................................................................................................... 53 6.3.1 Architecture and Design Goals ........................................................................................... 54 6.3.2 Topology ............................................................................................................................. 54 6.3.3 Messaging .......................................................................................................................... 54 6.3.4 Performance ....................................................................................................................... 55 6.3.5 Security ............................................................................................................................... 55 6.4 Third Party Applications Providers ............................................................................................ 56 6.4.1 Parlay .................................................................................................................................. 56 6.4.1.1 Requirements to adopt Parlay/OSA........................................................................................... 57 6.4.1.2 Service discovery ...................................................................................................................... 58 6.4.1.3 Security in Parlay/OSA ............................................................................................................. 58 6.4.1.4 Available standards ................................................................................................................... 59

7.

COMMERCIAL AND TECHNICAL FEASIBILITY OF APPLICATIONS AND SERVICES FOR HAPS.................................................................................................................... 60

7.1 7.2 7.3

Types of Information, Services and Applications Suitable for HAPs ........................................ 60 Parameters for Services and Applications ................................................................................ 60 QoS ........................................................................................................................................... 61 7.3.1 QoS Parameters ................................................................................................................. 62 7.3.2 Traffic classes and QoS ..................................................................................................... 62

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7.4

Analysis and Derivation of Favoured Services and Applications .............................................. 63 7.4.1 Competitive Technologies to HAPs – attributes and costs ................................................. 63 7.4.1.1 Broadband Penetration .............................................................................................................. 64 7.4.2 Cost Comparisons .............................................................................................................. 67 7.5 Candidate Services for HAPs ................................................................................................... 69 7.5.1 Applications for CAPANINA Trials ...................................................................................... 70 7.5.1.1 Trial 1 : Tethered Aerostat ........................................................................................................ 70 7.5.1.2 Trial 2 : Stratospheric Balloon .................................................................................................. 71

8.

CONCLUSIONS............................................................................................................ 72

8.1 8.2 8.3

Candidate Services for HAPs ................................................................................................... 72 Candidate Services for the CAPANINA Trial ............................................................................ 73 Recommended Further Work ................................................................................................... 73

SYMBOLS AND ABBREVIATIONS..................................................................................... 74 REFERENCES .................................................................................................................... 76 APPENDIX 1 : SURVEILLANCE PAYLOAD ....................................................................... 79 Video Surveillance............................................................................................................................... 79 Video surveillance by police forces .............................................................................................. 79 Video surveillance for security ...................................................................................................... 80 Video surveillance for road traffic monitoring and control ............................................................ 80 Infra-red and Radar surveillance .................................................................................................. 80 Remote monitoring and control ........................................................................................................... 80

APPENDIX 2 : UMTS .......................................................................................................... 81 3-G applications carried by HAPs ....................................................................................................... 81 Advantage of HAPs over satellite for UMTS ....................................................................................... 81 Broadcast / Multicast to UMTS handsets ............................................................................................ 81 Implementation options ....................................................................................................................... 82 UMTS Base Station Backhaul ............................................................................................................. 82

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LIST OF FIGURES Figure 1: Typical Network ................................................................................................................... 15 Figure 2: Typical capacity and mobility aspects of some radio access systems.......................... 18 Figure 3: UMTS/MBS boundary .......................................................................................................... 20 Figure 4: Predicted zenith monthly attenuation statistics at 48 GHz for 40°N, 16.3°E .................. 22 Figure 5: ITU and KWSA model predictions for 48 GHz atmospheric attenuation statistics at the zenith ................................................................................................................................. 22 Figure 6: Rain attenuation distributions at 27.5 GHz; Reston, VA; Elevation angle is 39° ........... 23 Figure 7: Time series from Bath, UK .................................................................................................. 23 Figure 8: Time series from Sparsholt, UK ......................................................................................... 23 Figure 9: Mapping of DAVIC, ATM-forum, UMTS and FSAN access reference models onto a HAP network. .................................................................................................................... 30 Figure 10: HAP Connectivity ............................................................................................................... 31 Figure 11: Single HAP, transparent transponder, single beam ....................................................... 33 Figure 12: Single HAP, multiple beam antenna without OBP .......................................................... 34 Figure 13: Single HAP, multiple beam antenna with on-board processing (on-board modulation and demodulation). .......................................................................................................... 35 Figure 14: Multiple HAP network connected by optical links .......................................................... 36 Figure 15: User Terminal Interface for DTV ....................................................................................... 37 Figure 16: Star configuration .............................................................................................................. 39 Figure 17: Roles within a HAP Network ............................................................................................. 51 Figure 18: Reference Frameworks ..................................................................................................... 52 Figure 19: Management and Control Plane Flows ............................................................................ 53 Figure 20: Digest authentication ........................................................................................................ 55 Figure 21: Interaction of applications and networks using Parlay ................................................. 58

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LIST OF TABLES Table 1: Wireless networking technologies ...................................................................................... 19 Table 2: Service Availability examples............................................................................................... 24 Table 3: HAPs Broadband Multimedia Scenarios ............................................................................. 27 Table 4 : Traffic Classes ...................................................................................................................... 41 Table 5 : Traffic Characteristics.......................................................................................................... 41 Table 6: Traffic Classes and QoS Parameters................................................................................... 62 Table 7: Broadband Penetration at 2002............................................................................................ 65 Table 8: DSL lines, cable modems and total broadband lines penetration in 2003 ...................... 66 Table 9 : Percentage increase in broadband in Q3 2003 .................................................................. 66 Table 10 : Broadband lines per 100 of the population ..................................................................... 67 Table 11 : Broadband Subscriber Forecasts ..................................................................................... 67 Table 12: Cost comparison of broadband networks in the UK ....................................................... 68

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1. Introduction The FP6 CAPANINA project is specifically about communications from aerial platforms delivering broadband to a community. This document forms Deliverable D01 “Candidate applications and services for broadband HAP delivery, including implications on network functionality and interfaces, e.g. for third party service providers” and is a part of Workpackage WP1.1 “Applications and Services Development”. Milestone M2 “Define market segments” within WP1.1 is also covered by this document. Within the CAPANINA project, an aerial communication platform is taken to mean a HAP (High Altitude Platform) flying at an altitude of 17-22 km and having a coverage diameter of up to 90 km. Broadband is taken to mean data rates above 256 kbit/s [25]. CAPANINA aims to show how burst data rates of up to 120 Mbit/s can be delivered to fixed or moving users anywhere within the HAP coverage area. The objectives of WP1.1 are to evaluate suitable existing applications, and to develop new mobile and fixed applications, that may be profitably carried on Broadband HAPs. The results from this report are processed by other activities in the study, such as WP1.2 “Business Modelling” and WP1.3 “Architecture Design and Interworking”. CAPANINA builds on the FP5 HeliNet project (IST-1999-11214) that illustrated the potential of broadband from HAPs and developed an outline system design. This document identifies candidate applications and services for broadband HAP delivery based on an understanding of the relative advantages and disadvantages of HAPs, together with sound commercial and business reasoning. One objective of the CAPANINA project is to test and demonstrate suitable applications via HAPs, ie ones that have been initially filtered by the commercial and business reasoning, so this report also highlights suitable applications for these tests. Deliverable D01 is concerned only with broadband applications and services, which are likely to be achieved using Ka- or V-band carriers in accordance with the ‘Broadband for all’ EC FP6 theme where CAPANINA belongs. There is commercial reasoning to support other services via HAPs, for example video and infrared surveillance, military applications and the provision of UMTS base stations to support 2G or 3G mobile communications. The addition of such payloads to that of a broadband payload may lead to a more robust business case for HAPs as a whole, but consideration of payloads other than broadband is outside the scope of this document. Similarly, lower data rate applications, such as voice, remote monitoring and control, etc., are not considered in this report unless they form part of a larger service mix.

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2. Broadband Overview 2.1 Broadband Definition The real value of broadband to users is the enhanced experience of the services and applications that can be delivered. Thus for email traffic the advantage over narrow-band might be “always on” availability, for web surfing faster access to rich multimedia content, for file transfer (e.g. music, photographs) faster delivery of content, for video a much improved picture and sound quality, etc. Service providers must emphasise the “value-add” of broadband for services and applications rather than simply the higher speed of broadband, important though that is. Many users would probably associate broadband with a particular speed or set of services, but in reality the term “broadband” is like a moving target. Internet speeds are increasing all the time, and at each new advance marketers eagerly emphasise just how blazingly fast the latest connection speeds are. It is revealing to look back at advertisements for 14.4 and 28.8 kbit/s modems, for example, just to see how every step is considered “blazing” at the time. It is also important to acknowledge that broadband technologies are always changing. One can therefore only really talk about the “current” state of broadband, and make tentative extrapolations, based on planned or incipient developments, that may or may not come to fruition in the future. The term broadband is commonly used to describe recent Internet connections that are significantly faster than earlier dial-up technologies, but it does not refer to a certain speed or specific services [24]. For instance, what was termed as a “fast” Internet connection two years ago is now designated as “narrow-band”. While the term broadband is used to describe many different Internet connection speeds, Recommendation I.113 of the ITU Standardisation Sector (ITU-T) defines broadband as a transmission capacity with sufficient bandwidth to permit combined provision of voice, data and video, with no lower limit and that is faster than primary rate ISDN, at 1.5 or 2.0 Mb/s. However, all bodies do not strictly follow this definition. The Organisation for Economic Co-operation and Development (OECD) [25] considers broadband to correspond to transmission speeds equal to or greater than 256 kb/s. For the purposes of this report, ISDN technologies are considered not to constitute broadband, despite the fact that some operators label ISDN as a “type of broadband”. While 256 kb/s satisfies the current definition for “broadband,” it is clear that as technology improves, we will soon reach a day when even ITU’s recommended speeds are considered too slow. A broadband connection typically comprises an unobtrusive device that sits between a user device (e.g. a PC) and a cable in a wall. Or it might take the form of a wireless LAN transmitter and network card. Unlike a telephone, a television (TV) or a computer, it is not at all obvious by looking at this hardware what broadband can do, and why one would need it. Broadband fits into the gap between being a service market and a hardware market. It is generally not worth signing up for a broadband service without first buying a computer and a network connection (like a DSL transceiver, a cable modem or a WLAN card). But equally, it is not possible to buy broadband off-the-shelf without first signing up for a network service. So service providers and manufacturers have to work together to sell the service. Compared with other major innovations, broadband can be a hard sell. The fact that most broadband services are partly substitutable by other services, for instance by narrow-band dial-up Internet access, means that it is even harder to convince users that have not yet experienced broadband to buy it. It is important therefore that broadband providers focus clearly in their marketing on what consumers really need. The temptation is, to focus just on speed of transmission, which is the one undeniable advantage of broadband over narrow-band alternatives. For example, the download or transfer times of a 3-megabyte file for various Internet connections are found to be [24]:

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Connection speed Time taken

100 Mb/s

10 Mb/s

2 Mb/s

1.5 Mb/s

512 kb/s

256 kb/s

128 kb/s

0.24 s

12 s

2.4 s.

16 s

47 s

1 min 33 s

3 min 7 s

Other examples of digital files sizes from the point of view of the consumer are the following: •

Movie

(1.5 hour - DVD)

4000 Megabytes

•

Movie

(1.5 hour - DivX)

650 Megabytes

•

3 minute music file (Wav file, raw)

35 Megabytes

•

Digital photograph (4 mega pixels, uncompressed)

11 Megabytes

•

ITU Internet for a Mobile PDF, 240 pages)

4 Megabytes

•

Generation (3 minute music file) (MP3 - 128 kb encoding)

3 Megabytes

•

Digital photograph (4 mega pixels, JPEG 10:1)

1 Megabytes

But while measures of transmission speed may be meaningful to engineers, they may mean little to the average consumer. To communicate this advantage to potential customers, it is vital to be able to explain this in terms of shorter waiting times for downloads or access to specific applications or content.

2.2 Advantages of Broadband The advantages of broadband are known, but it is useful to identify the primary ways in which broadband is having, or is likely to have, an impact on societies globally and therefore on the Applications and Services. Some of these advantages can be summarised as follows: [24, 25, 26] •

Sharing of knowledge can be enhanced by ensuring equitable access to the Internet, which is considered as a source of information for educational, scientific, economic, social, political and cultural activities.

•

Broadband enables people to conduct two-way communications at high speed over the Internet, exchange vast amounts of content and data, and benefit from an “always-on” mode of communication.

•

In the information society, many types of face-to-face contact, for instance, the provision of education and medical information, as well as administrative and government procedures, could be replaced by two-way communication over the Internet. At the same time, a tremendous body of knowledge and information is being created in an attractive and accessible format. By enabling the exchange of large amounts of content over the Internet, broadband is also helping to attract further investment in Internet software and network deployment.

•

Broadband is becoming a more significant tool that is accessible to all for the attainment of truly pervasive communications. This goes some way towards the fulfilment of access to knowledge for all as a basic human right—a goal that has been evoked in a number of regional and international declarations and that forms one of the main tenets of the Principles developed as part of the United Nations World Summit on the Information Society (WSIS-2004-Geneve).

•

Broadband contributes to building public awareness of the capabilities of ICTs (Information and Communications Technologies) to improve quality of life by circumventing traditional constraints like distance and time. It can also contribute to economic revitalisation.

•

There is also widespread understanding that the active introduction of broadband Internet and other ICTs has contributed to the economic development of many countries, including most of the OECD countries [25].

•

Conversely, the economic impact on developing countries has not been clearly proven owing to the limited application of the newly emerging ICTs and a relative lack of reliable analytical studies and data. Generally speaking though, broadband Internet is widely recognised as a catalyst for the economic development of a country, whether developed or developing, in the long run.

•

The development of broadband is also bringing about a paradigm shift in levels of information availability, and therefore in accountability, particularly in government processes. Wider public access to government information, and the opening up of information on public networks, underscores a commitment to democracy and good governance. Furthermore, depending on the

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legal system of each country independent, pluralistic and free mass media and other communication media are expanding as an, important means of fostering public information, societal development and social cohesion. •

Broadband not only makes possible “always-on” communications, but will in the future enable the interconnection of online and off-line appliances that are integrated not only at the network level, but also at the content level. The ease with which information can be passed from one context, system or appliance to another will introduce a whole new dimension to information flows.

•

Broadband development is also already increasing the urgency with which a host of issues need to be addressed concerning intellectual property rights, personal privacy, freedom of information, regulation and governance at the national level (with the associated issues of sovereignty and national law). Security at all levels, from personal, to corporate, to international, also needs to be considered - in turn raising technological standards issues.

2.3 Broadband Services Classification Users typically demand a wide range of services from their mobile handsets. Quality of service (QoS) standards for the Universal Mobile Telecom. System (UMTS), which is considered limited up to 2 Mb/s, specify four main classes of services [33]: o

Conversational services (e.g., voice and video telephony)

o

Streaming services (e.g., real time radio and television)

o

Interactive data access (e.g., the Web)

o

Background file transfers (e.g., email and FTP).

The first two services can be categorised as inelastic, the later two elastic. These distinct service categories have starkly different requirements. For example, conversational and streaming classes will trade packet error rate in favour of low-latency packet delivery. In contrast, a low packet loss / rate is paramount for the interactive and background classes (for example UMTS facilitates a packet loss -6 rate as low as 10 ). The classification of broadband services and applications can be done according to ITU-T Recommendation 1.211 [34], which is for fixed broadband integrated services digital network (BISDN); it includes applications with data rates in the range of MBS (e.g., high definition video and high multimedia applications). An application can be defined as a task that requires communication of one or more information streams between two or more parties that are geographically separated, and is characterised by service characteristics, and also traffic and communications characteristics. A service is a set of applications with similar characteristics. A single application can be classified as a service if it has a common set of characteristics, the service characteristics named above. This is a general way to classify applications and group them into classes (of services), as is done in ITU-T I.211; one can generalise it for the mobile communications market (UPC-12). In this context the services can be classified according to their service characteristics following literature from other Projects with EU sponsorship. Possible classifications are: o

Intrinsic time dependency (time or non time-based)

o

Delivery requirements (real-time or non real-time)

o

Directionality (unidirectional or bi-directional)

o

Symmetry of communications (symmetric or asymmetric)

o

Interactivity

o

Number of parties

Communications can be either unidirectional or bi-directional, and the latter can be either symmetrical or asymmetrical. It is also important to distinguish the concepts of intrinsic time dependency and of delivery requirements. 29th Jan 2004


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Time-based information must be presented at specific instants to convey its meaning, i.e., time is an integral part of the information to be communicated or the information has a time component. Typical time-based types of information are video, audio, and animation, while non time-based information includes images, graphics, and text. An application can include both time-based and non time-based information. In terms of delivery requirements, a real-time application is one that requires information delivery for immediate consumption. In contrast, non real-time information may be stored (perhaps temporarily) at the receiving points for later consumption. The former requires sufficient bandwidth, while the latter requires sufficient storage (and potentially bandwidth as well, if delivered at high speed). According to ITU-T 1.211, services can be the classified as interactive or distributed. Interactive services have a two-way exchange of information (other than control signalling) between two subscribers or between a subscriber and a service provider, and include the following categories: o

Conversational

o

Messaging

o

Retrieval services.

Distributed services are those in which information transfer is primarily one-way, from service provider to subscriber. They include broadcast services, where the user has no control over the presentation of the information, and cyclical services, which allow the user some measure of presentation control. A brief description of these categories follows [28]: Conversational services provide the means for bi-directional dialog communication, with bidirectional real time (not store-and-forward), end-to-end information transfer between two users, or between a user and a service provider host. Messaging services offer user-to-user non real time communication between individual users via storage units with store and forward, mailbox, and/or message handling (e.g., information editing, processing, and conversion) functions. Retrieval services provide the user the capability to retrieve information stored in information centres (i.e., in general, available for public use). This information is sent to the user on demand only, with the possibility of being retrieved on an individual basis. Broadcast services provide a continuous flow of information, which is distributed from a central source to an unlimited number of authorised receivers connected to the network. Each user can access this flow of information, but has no control over it (e.g., the starting time or order of the presentation of the broadcast information). Cyclical services allow distributing information from a central source to a large number of users. However, the information is provided as a sequence of information entities (e.g., frames) with cyclical repetition. So the user has the ability of individual access to the cyclical distributed information, and can control start and order of presentation. The basic service components are audio, video and data. Moreover, audio can be subdivided into voice and high-fidelity audio, video can be supported by interactive video and DVB (Digital Video Broadcasting), whereas data can support low, medium, and high data rates.

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3. Future Generation Broadband Services and Applications In the short term, European Telcos will offer DSL (Digital Subscriber Line) as a route to broadband, and cable operators will offer voice and broadband services on their cable TV networks. Satellite and BFWA (Broadband Fixed Wireless Access) will offer a broadband route to those (mainly rural areas) where DSL and cable does not reach. UMTS (Universal Mobile Telecommunications System) will offer services to mobile users. Only fibre offers truly large bandwidth. The next stage in broadband development for Telcos will probably be the introduction of VDSL (Very-high-data-rate DSL). This will involve fibre to the street cabinet or PCP (Primary Cross-connect Point) and provide significantly higher data rates than achievable through DSL and therefore enhanced services and applications. Eventually, fibre will extend to the home. A problem for terrestrial cable/fibre solutions is the economics tend to dictate that service is provided to the larger population densities first. Citizens in rural locations are therefore disadvantaged. HAPs may provide a solution here. The precise nature of the future generation of broadband integrated services is a matter of some conjecture and operators will therefore need to manage market, commercial and technology uncertainties over the coming years. However, some basic trends can be identified, based on the vision of next generation networks outlined in the ITU-T Y. series recommendations and Next Generation Network (NGN) initiative [45], which enables a more confident prediction. In the NGN concept, Internet technology (IP protocol, routing, etc.) and high-speed access and basic operator requirements (reliability and management, etc.) will be applied to achieve managed IP networks. NGN also requires the support of value added services building blocks. European future generation networks will offer cost reduction and the development of new "productindependent capabilities". There will be a continuing transformation from a narrow-band world to a world based on IP/packet technology where there is a high degree of convergence between fixed and mobile networks. Within this new world, customers will want to personalise their own services and have confidence that their network operator(s) will reliably and simply manage all their information and communications needs. A typical network will therefore migrate to a series of interconnected routers. Core Router

Metro Router

International networks Internet peering

Multi service access device

Fibre to the PCP Fibre to the user Figure 1: Typical Network

International access and Internet peering will be established into Core Routers. Metro Routers will undertake switching around the network and will connect to multi-service access devices. These will connect into the access network, e.g. mobile, land-lines, HAPs, etc. Within the terrestrial network, Telcos will extend fibre to the PCP or business in the first instance, and eventually to the home. Cable companies serving the access network will similarly migrate from copper to fibre networks. 29th Jan 2004


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Architectures will be developed covering the home environment, the Access Network, a common IP core network, PSTN and Mobility options, and an Intelligent Service Layer. This architecture provides direct customer control of services and operational control of the network and systems elements. To date, many operators have tended to build new networks alongside existing ones, resulting in multiple networks and billing systems. The future network will see these consolidated so as to reduce capital and operational costs. We need to go from multiple networks to multi service networks with fewer network elements. The new model will be one in which all services use the same functions in the network, but the customer who accesses them sees them as very different services. Operators must ensure proper switching through the network, along with large-scale support such as billing. As an example MPLS (Multi Protocol Label Switching) is proposed as a base technology for using label switching and for the implementation of label-switched paths over various packet based link-level technologies, such as Frame Relay, ATM, and LAN technologies (e.g. all forms of Ethernet, Token Ring, etc.). This includes procedures and protocols for the distribution of labels between routers and encapsulation. New services such as broadband video-on-demand, games, music, two-way calling will be integrated into the same broadband integrated network. These services will require real time and non-real time connectivity and two-way communication - developed from a range of new ideas. The new networks will support mobility, through fixed and mobile access. It will be personal to the user and enable seamless operation to different suppliers and services, no matter where the user is. Future integrated services networks will offer bandwidth on demand and will have comprehensive network management with reconfiguration and self-healing functionality. Different QoS will be offered depending on content and requirement. Users will be offered secure communications links with instant access to a myriad of services. End-to-end managed QoS is the vision of the service-provider, with vertical integration of the management stacks to allow automated policing of SLAs (Service Level Agreements) and to allow automated fault reporting and network healing.

3.1 Broadband Market Growth The business sector, in particular that of SMEs, is likely to form a substantial proportion of the broadband market in the earlier stages of a country’s development. In many countries, some analysts estimate that over 70% of connections will be to SMEs rather than to small sites of corporate organisations [6]. This is significant for Europe, since the number of SMEs is 20% higher in Europe than in the US. Growth of the (potentially huge) domestic market is heavily dependent on the applications available and the prices charged to the consumer. Provision of new services, e.g. VoD, at the right price could have a significant impact. Broadband market growth is dependent on both the network availability and the applications available. The commercial reality is that broadband applications will not be developed until the network exists to support them, but the network will not attract customers (and make money) unless there is a good reason to pay the premium rates that must be demanded. Network providers are solving this conundrum in the first instance by building ADSL networks in the expectation that the market will grow as mass-market applications are developed and interest is stimulated. Beyond ADSL (and cable modems), having whetted the appetite of consumers for broadband, the next stage is to build fibre networks, eventually to the home, and with them the opportunity for more sophisticated and bandwidth-hungry applications, such as VoD. These future-generation fibre broadband networks, and the high data rate applications that are supported by them, will be only be available initially to citizens in areas of high population density. This will create a digital divide, disadvantaging citizens in rural areas. HAPs could enable a faster roll out of next-generation broadband and help to solve this problem. As well as the basic applications, always-on broadband connections offer service providers an opportunity to bundle together a range of additional value-added services, especially to business 29th Jan 2004


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users. There will probably be take up in these areas from companies with multiple sites from the hightechnology, finance and media sectors [7]. Broadband users need security, particularly firewalls and virus protection. Value added services could include teleworker packages and secure VPNs. Voice services (VoIP) and ISP services (email, web hosting) could be supplemented by remote LAN management, and remote management of user storage media (e.g. for multicast file delivery). Broadband is forecasted to be the biggest revenue growth of all business data services over 2002–7 [8]. As broadband is extended and the market grows, HAPs and other technologies such as satellite, BFWA and UMTS, will have a part to play in ensuring that rural communities are not disadvantaged. These technologies may also serve specialised market segments, e.g. broadcast / multicast, mobiles, temporary venues, etc.

3.2 Future Multimode Broadband Systems Future broadband radio access systems will consist of several interconnected/integrated subsystems, and will seamlessly provide services to both fixed and mobile users [27, 28]. Such a system may include FWA (Fixed Wireless Access), MBS (Mobile Broadband System), and BSM (Broadband Satellite Multimedia). These components will serve much the same market, but may well be based on different architectures, broadband access technologies, and coverage. Future-generation broadband systems will aim to support a wide range of services and bit rates. The transmission rates may vary from voice and low-rate messages to very high-rate multimedia services requiring rates in excess of 100 Mbit/s. The communications environments vary, e.g. for fixed or mobile terminals. In the mobile case, variables include: •

the grade of mobility

•

the cellular infrastructure

•

the required symmetric and asymmetric transmission capacity

•

whether indoor, outdoor, urban, metropolitan or rural area propagation scenarios.

Hence air interfaces with the highest flexibility are required in order to maximise the area spectrum efficiency expressed in terms of bits per second per Hertz per square kilometre in a variety of communication environments [29]. Broadband radio access networks have traditionally developed in different directions for the different areas they have addressed. They have been associated with standards for existing networks like interactive cable or interactive satellite networks. User flexibility and interoperability between networks will require harmonisation of operation, service provision, and network management. The user should be allowed to move between the different segments. Common management for services, network resources, and customers, covering both fixed and mobile segments, has started to become a necessity. It is now commonly accepted that the provision of services like interactive TV, Internet, Teleeducation, and advanced home office services are necessary for development and growth. The development of a low-cost millimetric wave broadband radio access systems for fixed and nomadic or mobile users will help ensure that as many people as possible have access to these services. Broadband radio systems would then perhaps be able to achieve higher penetration (take-up) than DSL twisted pairs or cable systems, dependent on cost. The market will range from residential to small and medium-sized businesses, including organisations, schools, universities and local authorities. With a broadband system, entertainment and business services will be provided on the same platform. The high return capacity available will allow new business to develop, making use of the new technology in delivery of the services. The traditional market segments, such as residential and business, no longer adequately describe the new combined market [30, 31]. Convergence of wide-band wireless access and Internet will be the next wave in the information industry, and it obviously becomes one of the foci of global investments. Fuelled by such emerging technologies as all-IP direct signalling, super digital signal processing, smart antenna transceiver, broadband and reconfigurable core, as well as converged wireless interfaces, the wireless system is taking on a more and more important role in Internet development. 29th Jan 2004


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As communications evolve to this convergence, a new architecture will be required to support highdata-rate connection from 226 kb/s to over 100 Mb/s with varying QoS (Quality of Service) based on the new spectrum requirement as well as the coexistence with the current spectrum for wide-band wireless. To meet these critical demands, improvements in the wireless physical layer (modulation, diversity, coding, etc.) and link layer (access control, bandwidth allocation, etc.) are necessary. Future systems are also expected to support various types of services based on ATM (Asynchronous Transfer Mode) transmission and IP (Internet Protocol), which require varying QoS. Some typical services and corresponding uplink/downlink data rates are illustrated in Figure 2 and the new technologies for broadband wireless networking can be summarised as follows:

M o b i l i t y

G S M

UMTS

Broadband radio MBS LMDS

S-UMTS BSM

0.01

0.1

1

10

100

Capacity (Mb/s)

Figure 2: Typical capacity and mobility aspects of some radio access systems

Table 1 illustrates the data rates, frequencies and range of operation associated with various wireless networking technologies.

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Table 1: Wireless networking technologies Speed

Name

Range

Frequency

Notes

11 Mbit/s

802.11b (Wi-Fi)

100 m

2.4 GHz

Most popular and widespread

54 Mbit/s

802.11a

50 m

5 GHz

Newer, faster, higher frequency

54 Mbit/s

802.11g

100 m

2.4 GHz

Fast, backwards compatible with Wi-Fi

54 Mbit/s

802.11e

NA

5 GHz

Adds QoS not present in a, b, or g.

70 Mbit/s

802.16 (WiMAX)

50 km

2-11 GHz

Very long distance, Metro net

10 Mbit/s

RadioLAN

35 m

5.8 GHz

Specialises in wireless bridges

1 Mbit/s

HomeRF

50 m

2.4 GHz

Replaced by HomeRF2

10 Mbit/s

HomeRF2

100 m

2.4 GHz

QoS, better encryption, not widespread

54 Mbit/s

HiperLAN2

150 m

5 GHz

European standard, QoS, for voice/video

NA

HiperMAN

50 km

2-11 GHz

European, compatible with 802.16a

1 Mbit/s

Bluetooth

10 m

2.4 GHz

Personal area network [not WLAN]

4 Mbit/s

Infrared LAN

~20 m

350,000 GHz

Same room only, no negative health effects

Table 1 Source: ITU, updated from “Internet for a Mobile Generation”, ITU, 2002.

3.3 Future Fixed and Mobile Broadband Services The 3G UMTS, as currently defined, will not be able to support broadband services since it limits the maximum transmission rate to 2 Mbit/s. Moreover, those 2 Mbit/s are only achievable at a very short range and under restricted mobility conditions. Furthermore, capacity might become an issue since a user may require the whole capacity of a cell to run a specific application. A new set of complementary systems, able to provide transmission capacities up to 150 Mbit/s to mobile users, will have to emerge. These systems are usually denoted by MBS and are a necessary step toward new generations since they will provide broadband transmission capabilities, one of the requirements of future networks. Figure 3 shows the UMTS / MBS boundary.

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User mobility

GSM/ HSCSD

GSM Slow mobility

GSM/EDGE

GSM/HSCSD

Fast mobility

MBS

UMTS

HIPERLAN

Movable

155M

2M

384k

144K

B-ISDN

64K

9.6K

ISDN

20M

Fixed

Service data rate (b/s)

Figure 3: UMTS/MBS boundary Around 10 years from now, it is anticipated that mobile broadband systems will play an important role in the mobile communications market, mostly in urban areas to cover hotspots in the centre of large cities, where very high demand is foreseen. However, today there is still some difficulty in the identification of such systems, primarily due to the emerging nature of future applications and today’s lack of customer interest in those contents or applications, which is delaying the deployment of broadband access wired networks. One of the main obstacles to its introduction consisted of the insistence on developing these services only from the technical point of view of telecommunications and computer engineers, hence not considering proper marketing input about what people really need. Due to the diversity of characteristics of the services to be supported, different requirements arise for resource usage and service component access by various applications; each application supported by these services has access to various service components. The amount of resources that must be available depends on the mixture of supported applications, and also the total number of users.

3.4 Future HAP Network Possibilities The business case for future HAP networks include applications that are outside the remit of the CAPANINA project. Discussion on these applications is therefore inappropriate within the main body of this report, although information on using HAPs for surveillance is provided in Appendix 1 and consideration of the use of HAPs for communication to UMTS mobiles is considered in Appendix 2. The business case also includes military applications that are similarly outside the remit of CAPANINA. The EC HeliNet project team provided the groundwork for future HAP network possibilities [10]. A key scenario is to provide applications and services on a long-term basis to SME and residential users. A HAP, in most cases, will form the final/first hop for transmission. Network connections will normally be provided by a backhaul link to terrestrial hubs, possibly via satellite. If satellite is used, appropriate note must be taken of the delay and its impact on applications. The HeliNet team also envisaged dedicated point-to-point services, e.g. to provide LAN interconnects between major and minor (office) sites. These may not require backhaul links as connection into a wider network may be accomplished (terrestrially) at the major site. 29th Jan 2004


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The team considered multiple HAP networks. Networking was shown to be achievable using inter-HAP links, backhaul links, or a mixture of both. These can serve separate coverage areas, thereby increasing coverage, or serve a common coverage area, thereby enhancing capacity through spot beams and frequency reuse. On-board caching was also suggested to reduce the backhaul requirements.

3.4.1 Impact of Ka/V-band propagation characteristics on services and applications HAPs typically operate as quasi-stationary radio-relays at altitudes of 17–22 km., so the earth-HAPs links are subject to the effects of the weather. The propagation characteristics of the signals travelling through the troposphere depend to a large extent on the frequency band used. Propagation issues include the geometry of the beams, rain scatter between the densely packed co-frequency beams in a HAP system, signal attenuation and fade duration, scintillation and multipath. The ITU and WRC-2000 [16][18] have allocated two frequency bands for fixed service (FS) using HAPs: 27.5-28.35 GHz and 31.0-31.3 GHz (Ka band) 47.2 – 47.5 and 47.9 – 48.2 GHz (V-band) The propagation characteristics of the frequency band chosen, combined with the climatic characteristics of the regions of interest and the QoS required, will be key factors in the HAP link budget and system design. A study of V-band services for satellite and HAPs [16], has highlighted serious QoS issues for some services and applications. V-band fade depths are so severe that sufficient fade margin may not be practically realisable to achieve the required QoS for certain services and applications. Live video services, e.g. TV and streaming, are most affected. Customers are likely to be dissuaded from a HAP service if they are forced to suffer too many outages. It may be that fade countermeasures techniques can mitigate QoS problems to some extent, however, the end-users might tolerate moderate outages for other services, e.g. WWW browsing, multicasts and file transfer, where the main impact is on a reduced throughput and therefore a slow-down in service. Figure 4 and Figure 6 illustrate the link-budget margins that would be required for a given Service Availability. It should be noted that these figures include rain attenuation only, while in practice there are a number of other contributing factors in total signal attenuation (gaseous absorption, reflections, etc.). Figure 4 shows the predicted monthly attenuation statistics for V-band fading in Southern Europe (Italy). It can be seen that, for a Service Availability of 99.9%, the signal attenuation at 48 GHz will vary between 15 dB and 40 dB, depending on the month of the year [16].

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Attenuation (dB)


100 90 80 70 60 50 40 30 20 10 0 0.01

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

0.1

1 Exceedance (%)

10

100

Figure 4: Predicted zenith monthly attenuation statistics at 48 GHz for 40°N, 16.3°E

100

ITU model, zenith KWSA model, zenith

Attenuation (dB)

80 60 40 20 0 0.01

0.1

1 Exceedance (%)

10

100

Figure 5: ITU and KWSA model predictions for 48 GHz atmospheric attenuation statistics at the zenith Figure 5 compares the ITU model for zenith attenuation at 48 GHz with the KWSA model (the KonefalWatson-Shukla-Akram model developed at the University of York in conjunction with QinetiQ). The KWSA model was found to correctly predict the atmospheric attenuation statistics at Spino d’Adda (Italy) from the experimental ITALSAT satellite, transmitting a beacon at 49.5 GHz [16]. It can be seen from figure Figure 4 and Figure 5 that a 20 dB fade margin would be required for 99.9% availability using V-band, and a 40 dB fade margin would be required during the worst month [16]. A 99.7% availability would require a 17 dB fade margin (22 dB worst month). 29th Jan 2004


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Figure 6 illustrates the rain attenuation at Ka-band [17]. The rain fading characteristics are less severe at Ka-band than at V-band, with 99.9% availability obtained with a 15 dB margin.

Figure 6: Rain attenuation distributions at 27.5 GHz; Reston, VA; Elevation angle is 39° Studies of V-band fade durations [19] indicate that the fade duration can exceed four hours on occasion with a fade depth of 10 dB, and one hour at a fade depth of 20 dB. Figure 7 and Figure 8 show measured fade durations in South West England on 8/8/99 at 49.5 GHz.

Figure 7: Time series from Bath, UK

Figure 8: Time series from Sparsholt, UK

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Table 2 illustrates the potential Service Availabilities that would be required for different services and applications over HAPs [16]. L4

Service

Delay tolerance

Errors tolerance

BW to user [kbit/s]

RTP/UDP

TCP

mean/pk

BW from user [kbit/s] mean/pk

Max Outage

Service Availability Required

Tolerance GENERIC Equivalent to (μ+3σ) RTT RTT RTT 140 330 533 ms ms ms

[%]

55 sec

99.9

LAN Interconnect

Medium

Medium

1000/1000 0

1000/1000 0

Web Browsing (HTTP1.0/1.1)

Medium

Medium

10/2000

10/100

99.9

File Transfer (e.g. SW backup)

Medium

Medium

10/10000

10/10000

99.9

Email

High

Medium

1/50

1/50

99.9

Content Distribution (multiple p-p)

High

High

1000/4000

1000/4000

99.9

Voice/Audio Streaming

Low

Low

5-64/5-64

5-64/5-64

30 sec

99.7

Video Streaming

High

Medium

1000/1000

1000/1000

30 sec

99.99

Content Distribution (IP Multicast)

High

Medium

1000/4000

0 or 10/64

N/A (e.g. 1 hour)

90

45 sec

30 sec

Table 2: Service Availability examples It can be seen from Table 2 that serious QoS issues exist for some services and applications if V-band is used. V-band fade depths are so severe that sufficient fade margin may not be practically realisable to achieve the required QoS. Live video services, e.g. TV and streaming, are most affected; www browsing, file transfer and multicast content distribution services less so. It may be that fade countermeasures techniques can mitigate QoS problems to some extent. The use of V-band frequencies is appropriate for inter-HAP links and satellite-HAP links that are above the atmosphere.

3.4.2 Fade countermeasures techniques and the impact on applications A future broadband HAP network is likely to communicate with fixed ground stations at millimetric wave frequencies, viz. Ka-band and V-band. At these frequencies, as we have seen in the previous

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sub-section, rain fading is a significant problem for some applications, and it is important to determine the QoS that can be tolerated for different applications. Future HAP networks will probably incorporate a degree of fading countermeasures. Rain fading is dependent on the climatic region, but it is likely that heavy rainfall cells will be localised so that not all links passing through the HAP will be subject to the same degree of rain fading. Fade countermeasures techniques include creating a pool of resource that can be adaptively given to links subject to fading. The resource pool can be of bandwidth or of power. All adaptive countermeasure techniques require a monitor and control mechanism with appropriate algorithms and some overhead management traffic. The onset of fading on a particular link must be noted, and the countermeasure technique introduced in good time. Depending on the progress of the fade with time, the countermeasure may need to be strengthened or weakened, with a consequent impact on the pooled resource. Generally the attack time of such countermeasures is less than the release time and this control mechanism could be modelled. Some applications can tolerate a user data rate reduction during fading. As an example, MPEG video coding techniques allow a trade-off between data rate and picture quality. Similarly, a TCP/IP data stream can tolerate a data rate reduction at the expense of a slower throughput. This would be more acceptable to the user than a link failure. Adaptive power control is one method of fade countermeasures whereby the network recognises the extent of rain fading on a given link and increases power accordingly. Additional power during fading can be given to the up-link, by requesting the user terminal to increase power, or to the down-link, by requesting an increase in HAP transponder output power (i.e. a spot-beam down-link power). Unfortunately, attenuation due to rain is severe at these higher frequencies, and studies indicate that an average 20 dB fade margin would be required in Southern Europe for 99.9% availability using Vband, and a 40 dB fade margin would be required during the worst month [16]. A 99.7% availability would require a 17 dB fade margin (22 dB worst month). Rain fading at Ka-band is significantly less than at V-band. It is probably impractical to provide such high power margins for reasons of power supply, interference and safety. Power on a HAP is likely to be derived from solar cells, with batteries storing power for overnight operation (especially significant for northern latitudes during the winter months). Power is also likely to be required for the HAP electrical engines. Interference and safety levels are the subject of standardisation activity in the ITU and ETSI. A survey should be carried out of interference and safety levels that have already been standardised and recommendations given on standards work to cover the HAP case in CAPANINA. Adaptive power control is a useful tool, and can go some way towards fade mitigation. However, it is unlikely to provide a complete solution because of the limited power budget on board the HAP (power drain and safety issues) and the impact of a high fade margin on price sensitive user terminals (notably SSPA power and antenna size). Adaptive FEC (Forward Error Correction) enables the FEC code rate to be increased during fading at the expense of increased bandwidth. Modems at both ends of the link would need to co-operate in this procedure. The fade margin could be increased by perhaps 5 dB at the expense of doubling the bandwidth. This is practical coding advantage of ½ rate convolutional coding with soft-decision Viterbi -6 decoding taken at an error rate of 10 . Reed Solomon and Turbo coding could yield a greater advantage [47]. Adaptive modulation allows modulation type to be changed during fading, e.g. from 16-QAM through 8-PSK and QPSK to BPSK, offering greater resilience to fading at the expense of a greater bandwidth. Again, modems at both ends of the link would need to co-operate. Fade countermeasures can yield significant benefits where the application can tolerate a reduction in data rate during fading. Adaptive rate modems would allow the data rate and hence bandwidth to be reduced during fading for the same carrier power. For example, a given carrier to noise ratio (C/N) might result in a high error rate at say 32 Mbit/s, perhaps even modem failure. However, if the data rate were halved to 16 Mbit/s, the noise bandwidth could be reduced by 3 dB with a consequent

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increase in C/N and decrease in error rate. A 6 dB advantage would be obtained if the data rate were to be reduced to 8 Mbit/s, a 9dB advantage for 4 Mbit/s and so on. TCP/IP file transfer applications can tolerate a reduction in data rate with the penalty of a reduction in throughput. This would be preferable to the user than an outage caused by a modem failure in a hostile C/N environment. Similarly, MPEG video encoding can suffer a reduction in data rate with the penalty of a reduction in picture quality. This would be preferable to the user than a complete loss of picture. However, adaptive video encoding would require the co-operation of the source provider, or re-encoding at the HAP ground station, and in practice may prove difficult to implement. In summary, a combination of fading countermeasures techniques could mitigate the impact of rain fading on user services and applications.

3.4.3 Security issues Radio signals from a HAP can be relatively easily received so it is important that data cannot be decoded by unauthorised users. The multiple access scheme likely to be used by a HAP, e.g. reservation slotted Aloha, TDMA, etc. provides a level of protection, but secure end to end communications are best achieved by a commercial product such as IPSec. This is particularly important for remote access to Intranets via firewalls, e.g. by teleworkers connected to the HAP. Applications will probably run over encrypted VPNs (Virtual Private Networks). For classified military traffic or control signals, encryption and the correct hardness level will be provided. This can be done at the packet level or using bulk encryption of multiplexed services. There has also been some recent work on the development of key management for multicast and broadcast systems [43]. It is apparent that the control of the HAP must also be protected against malpractice, for example RF jamming, whether deliberate or accidental. The modulation and coding scheme should be adaptable to the particular situation, for example the use of spread-spectrum to protect against jamming and the choice of codes to make subtle jamming difficult. Also, on-board processing prevents the jamming signals from reaching the users.

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4. Operating Scenarios 4.1 HAPs Network Scenarios ETSI have reviewed the standardisation issues with respect to services and architectures for Broadband Satellite Multimedia [3]. Much of this work has relevance for HAPs and should be noted. HAPs can be used to provide broadcasting and multicasting services as well as point-to-point services. Although there are similarities with the satellite scenario studied by ESTI, a different market segment for HAPs exists. HAPs, for example, are not suitable for long-haul communications, but they can provide local and backbone networks and access networks, including access to added-value services such as Internet applications. Direct connectivity of corporate Intranet/Internet is more limited by HAPs than satellite because of the smaller coverage area. The ETSI model divides the global IP network into three parts, core network, distribution network and access network. ETSI describe the distribution network as an intermediate IP sub-network that is used to connect an access network into the core network Table 3: HAPs Broadband Multimedia Scenarios ACCESS NETWORK SCENARIOS Corporate intranet

Corporate internet

SME intranet SME internet

POINT-TO-POINT

MULTICAST

BROADCAST

Corporate HAPs network, i.e. site interconnections

Corporate Multicast (e.g. Data distribution Video conferencing) IP multicast RT streaming ISP caching SME multicast IP multicast RT streaming ISP caching IP multicast RT streaming ISP caching IP multicast RT streaming ISP caching

Datacasting TV broadcast (private)

Internet Access via corporate ISP or via 3rd party ISP Small HAP network Internet Access via 3rd party ISP

ISP caching

ISP caching

Soho

Internet Access via ISP Company access via VPN

ISP caching

Residential

Internet Access via ISP

DISTRIBUTION NETWORK SCENARIOS Content to Edge

POINT-TO-POINT

MULTICAST

BROADCAST

ISP to Backbone

IP multicast RT streaming Caching at ISP/Edge

TV broadcast (public)

CORE NETWORK SCENARIOS ISP interconnect

POINT-TO-POINT

MULTICAST

BROADCAST

Trunk interconnect

N/A

N/A

ISP caching

Table 3: HAPs Broadband Multimedia Scenarios

4.1.1 User scenarios In this section we consider the potential users of HAPs and the services and applications that they are likely to require. A deeper treatment of the services and applications themselves is given in Section 5 (Potential Applications for Services for HAPs, page 41)

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A broad range of user scenarios can be considered. The advantages and disadvantages of HAPs relative to alternative transmission systems (such as terrestrial copper/fibre, terrestrial radio and satellite) must be kept in mind in developing the services, applications and business case for HAPs. The terrestrial cable/fibre infrastructure does not (yet) offer broadband connectivity to many rural locations within the EU, and this is even more apparent in new member states and in developing countries. Low cost broadband via DSL, using twisted pairs, is widely available in some countries, but is usually limited to 2 Mbit/s or less, so cannot offer truly high-speed broadband both-way services. VDSL is proposed by many administrations, but is not yet widely implemented. Satellite can offer a broadband solution but it is better suited to broadcast applications. HAPs, with its superior link budget, small cellular structure and frequency re-use, is better positioned for cost competitive point to point links. Satellite is better positioned for wide distribution TV broadcast applications although HAPs, like terrestrial radio, may be better suited to local or regional TV distribution. Only radio can support mobile applications; HAPs have a part to play here with the potential to provide broadband communications to vehicles and trains. 4.1.1.1 At home The domestic European market is potentially large and lucrative but, to be successful, the cost of the HAP user terminal equipment and service charges must be low, and services tailored to the market. The content will probably include broadband Internet and entertainment video (TV or IP streaming). Email and data transfer, e.g. exchange of music and photographs, are gaining popularity in the domestic marketplace and would benefit from a broadband platform. However, if DSL penetration reaches its targets in Europe it will provide strong competition to HAPs for services such as broadband Internet. Satellite offers very strong competition for TV to the home, so HAPs will need a niche market here to be successful (VoD, neighbourhood TV?). HAP might be more successful in the domestic market in the developing countries. The introduction of VDSL (Very high data rate DSL) will promote a new generation of services and applications that require higher data rates than DSL can support. VDSL will initially only be available in areas of high population density, and HAPs may find a market in supplying new-generation broadband services to domestic customers in urban / rural areas, as well as to users in countries who are slower to deploy VDSL. 4.1.1.2 In the office Broadband Internet is a strong candidate service for HAPs, especially in areas of poor terrestrial infrastructure and without the immediate likelihood of DSL. Business is more likely to pay a premium rate for a broadband service than domestic customers. Emails sent and received with large data file attachments are strong potential applications. SME/corporate applications tend to require a more symmetrical data flow, and it may be that HAP is better suited to this than ADSL (although terrestrial SDSL would be competitive). An office might be regarded as a single subscriber, but within that office could be many users (employees) all wishing to access broadband. The total bandwidth requirement may be higher than could be accommodated by one ADSL line. There are terrestrial solutions to this (e.g. multiple ADSL lines with routers, or private circuits), but HAPs could also provide a high bandwidth solution. As described above, the advent of VDSL is likely to drive a new range of rich content, bandwidthhungry applications for business, but these would initially only be available to high population density areas. HAPs could be a solution to business in urban or rural locations, in advance or possibly in place of VDSL. 4.1.1.3 Remote offices There is a common requirement to link a Corporate HQ with remote offices via a broadband Intranet. This opens up a series of common applications throughout the company, including the ability to download large data files from company servers. Broadband access to the Internet can be easily provided via the Intranet. Security is an issue, so VPN and IPSec must be considered. Other applications such as business TV, distance learning/training, videoconferencing, etc. are also

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possibilities. Another consideration is where DNS, DHCP is performed, since the location of these services affects the backhaul traffic / remote terminal complexity trade area. 4.1.1.4 Teleworkers The quality of life for citizens, the maintenance of a work-life balance and business efficiency is enhanced if working from home is an option. Quality communications, including audio-visual applications such as videoconferencing, is a prerequisite. Requirements for Teleworkers are broadband Intranet/Internet and other services applicable to remote offices. Like remote offices, Security is an issue, so VPN and IPSec must be considered. 4.1.1.5 Hospitals In addition to the usual broadband Internet/Intranet services, specialised audio-video medical applications are likely to be of value. Distance learning applications can be augmented by live bothway audio-video assistance to disaster areas. 4.1.1.6 Schools, Colleges and Universities Services and applications will include broadband Internet/Intranet and distance learning. 4.1.1.7 Government Departments Government departments require both broadband intra-communication, and the ability to provide information to the citizen.

4.1.2 Summary of access network requirements The access network design should ideally be covered by open standards. The FSAN (Full Services Access Network) initiative was developed by CSELT, which is the research laboratory facility of Telecom Italia. FSAN introduces a term SNI (service node interface), which is located at the interface to the core network, such as a gateway. The SNI is specified to be VB5 compliant and is known as a VB5 reference point. DAVIC (Digital Audio Visual Council) and the ATM Forum also have access reference models and specify this interface to be VB5 compliant, but they call the interface different things; DAVIC calls it A4, ATM forum calls it ANI. The UMTS reference model calls this interface Iu but does not specify it to be VB5 compliant. Figure 9 shows the mapping of DAVIC, ATM-forum, UMTS and FSAN access reference models onto a HAP network.

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HAP Network Element

Access Switch

Service Node

Access Switch

Gateway

NT

User

HAP Access Network

FSAN

ATM-F

DAVIC

UMTS

UNI ATMF

SNI VB5 ANI VB5 A9

Yu

UNI W

A4 VB5

A3

A2

Iu

UNI X

A1

A1* UNI

Uu

Cu

Figure 9: Mapping of DAVIC, ATM-forum, UMTS and FSAN access reference models onto a HAP network. It can be seen from the discussion on “user scenarios” that most users require direct broadband connectivity from their terminal into a core network, from where they can obtain a defined broadband service or run an application. This link forms the access network. In this respect, user requirements are a similar market to broadband satellite multimedia as defined by ETSI [3]. When used in this way, HAPs can connect user network interfaces, located at customer premises, to a service node interface of a broadband core network, as follows: The target users are residential households, SMEs or corporates. •

All HAPs systems are expected to support IP.

•

HAPs systems may support both symmetric and asymmetric data flows.

•

In general, the system will use multiple access to the radio bandwidth in order to optimise the efficiency with which multiple users utilise the spectrum.

•

Systems may be deployed by Telcos, who provide network services to the public, or by private operators, who use the network for their own purposes.

•

HAPs systems should allow both terminal interoperability and service interoperability, as suggested by ETSI definitions for the satellite case (see below)

•

HAPs systems should allow for network management functions consistent with those used to manage terrestrial networks.

Definitions of Terminal and Service Interoperability for HAPs (based on ETSI definitions for the satellite case [3]): Terminal interoperability is defined as the ability of a HAPs user-terminal designed and built according to the standards to inter-operate with a HAP system designed and built independently to the same standards and to provide defined services according to an "inter-operation profile" specification. This implies that a conforming terminal could in principle be used to access more than one HAP satellite system. In addition, it shall be possible for 3rd party manufacturers to produce conforming terminals.

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Service interoperability means the ability to offer the same services over different systems. Once protocol interoperability between networks is attained, service interoperability is dominated by the respective Service Level Agreements (SLAs) of the inter-operating networks.

4.2 Topology Various types of topology can be considered, both for the HAP(s) and for the ground segment. Connectivity can be considered as: •

Access Network – The HAP connects the end user(s) to the core network edge. This is the classic configuration for broadband Internet/Intranet and for multicast/broadcast services to (low cost) user terminals.

•

Content Distribution – The HAP connects a content provider to the core edge. As above, this configuration can be considered as an access network, but for content distribution a high bandwidth is essential in the return (ground segment to HAP) direction. Content distribution could include TV and VoD services.

•

Core Network Trunk (Bearer Services) – The HAP connects two points within the core network. Point to point private circuits (bearer links) could form a part of the core network perhaps as part of a core network overlay to provide network resilience.

•

HAP Private Network – The HAP connects two or more users to each other, without direct connectivity to the core. This is the classic use of VSAT to provide a private data network, for example for point of sale credit card authorisations, stock control, financial and insurance services.

It can be seen that, in most cases, a link into the core terrestrial network is required. HAPs are probably best considered as a part of the access network with a (low cost) HAP terminal located at user premises offering both point-to-point and point-to-multicast services. Terminals providing connectivity to the core network and content distribution will probably require a larger (antenna size and transmit power) and more robust terminal to give an appropriate QoS. HAP HAP

HAP Core Network Trunk

Core Network

Access Network (core to end user(s))

HAP Private Network (users connected, but no connection to core)

Content Distribution (end user to core and/or to other users)

Point to Point and/or Point to Multipoint

Point to Point and/or Point to Multipoint

Figure 10: HAP Connectivity

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Figure 10 shows these four topologies. The HAP on the left illustrates a typical access connectivity, with a number of user sites connected to a core network via the HAP. One or more users could have content for distribution. The HAP in the centre illustrates a core network trunk, i.e. connectivity between two points in a core network, either as the primary connection or an overlay. Finally, the HAP on the right illustrates a HAP private network, independent of the core.

4.2.1 HAPs topology The complexity of HAPs can vary from a single HAP, transparent transponder, wide beam service, to multiple HAPs connected by optical links, each with on-board processing (on board modulation / demodulation and switching) and multiple spot beams. Additionally, a HAP could have direct connectivity to a satellite, perhaps to enable a connection to a core network that is independent of the ground based infrastructure; this could be a useful attribute when HAPs are used in disaster situations, To some extent, the HAP configuration is independent of the applications and services that can be carried, although the efficiency of some configurations makes them more suitable for certain applications and services. For example, broadcast services, such as regional TV, can be delivered using a (cheaper) single beam transparent transponder. Services that tend to be point to point, such as broadband Internet/Intranet and VoD, are more efficiently carried using spot beams and on-board processing. The HeliNet project paved the way in suggesting three-payload configuration options [10]. The choice depends on many parameters, including the size and weight limits imposed on the HAP payload. Option 1 – size/mass efficient configuration. Hardware is placed wherever possible on the ground and not on the HAP, so there is no on board processing and the HAP contains a transparent transponder. If the HAP contains a multiple beam antenna, the architecture is made more difficult to design because efficient ways must be found to aggregate and split up the traffic between cells. All traffic must be brought to the ground for processing, which means there can be two-hop links and hence increased delay. Also it is necessary to have a gateway station in every beam. Inter-HAP links are made more difficult without on board processing or routing, so they would only be of benefit when there was other network infrastructure. Option 2 – on board switching and routing. Switching and routing hardware is placed on the HAP, allowing local traffic to be handled on the HAP. Traffic can more easily be routed via inter HAP links. This makes a network of HAPs less dependent on ground-based infrastructure and networks. Option 3 – on board switching, routing and caching. As much hardware is possible is placed on the HAP, reducing the HAPs network reliance on ground based-networks. The addition of caching reduces the backhaul requirements, allowing large libraries of information to be stored for high-speed access by the user. 4.2.1.1 Transparent transponder(s), single beam Figure 11 illustrates the transparent transponder, single beam case, which is the simplest implementation of a HAP. The layer 1 HAP communications payload is a Ka-band or V-band transponder (or multiple transponders), connected via suitable filters to a single antenna and feed structure. There may be two antennas, one for the gateway feed and one towards the users. There is no on-board processing. It is probable that a beacon will need to be transmitted from the HAP to enable optimal earth station pointing and tracking. One of the ground terminals may (or may not) be connected to a terrestrial core network. The topology is flexible and can be Star, Mesh or a series of point- to-point links with manual set up and control. Non-broadband payloads, such as UMTS, military or surveillance and the HAP control and communications payload are not shown in the figure.

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HAP

Ground Terminals

Figure 11: Single HAP, transparent transponder, single beam 4.2.1.2 Single HAP, multiple beam antenna, without on board processing Figure 12 illustrates a single HAP, multiple beam antenna, without on board processing (OBP). Here we consider a number of spot beams in the up-link direction, with a single wide-area beam in the down-link direction. This arrangement provides some of the link budget and frequency re-use advantages of spot beams, but without the complexity of OBP, and it is analogous to similar schemes used on satellite, for example the Eutelsat Hot Bird 6 Ka-band payload [47]. The link budget advantage of the spot beam up-links is realised in a lower EIRP from the user terminals than would be the case for a wide-beam up-link. This enables the cost of the user terminals to be reduced. The case for this type of configuration is strengthened if the mix of applications includes a significant broadcast element. The precise antenna beam arrangement is for further study. It would be possible to construct a number of spot beam antenna profiles using a shaped reflector, multiple feeds or to use phased array technology. It may be that HAPs would use separate antenna elements for up- and down-links, but again this is a matter for further study and is dependent on a number of service, technical and cost parameters, e.g. frequency allocation / separation especially at V-band, cost of diplexers, etc.

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HAP Transponders : static switching between spot beam up-links and a wide-area beam down-link

Figure 12: Single HAP, multiple beam antenna without OBP 4.2.1.3 Single HAP, multiple beam antenna with on-board processing (on-board modulation and demodulation). Figure 13 illustrates the on-board processing, switched beam example. This arrangement allows significant packet switching capability, but with the penalty of increased HAP communications payload size and weight. On-board demodulators and modulators interface with the on-board switch, allowing dynamic routing of packets within and between beams. An on-board ATM switch and/or MPLS routers provide significant switching flexibility, and this flexibility (and complexity) is extended if dynamic beam shaping techniques are used to provide bandwidth where it is needed. An OBP switched antenna system negates the requirement for a wide-beam down-link as in the previous multibeam non OBP example, so probably only spot beams will be used from the HAP (unless broadcasting is a significant service requirement). Also, as for the previous example, the HAP antenna configuration (separate antennas for up and down link, shaped reflector, phased array technology, etc.) is a matter for further study. The concept of an RF (or IF) switch that does not require on-board demodulation and modulation has been used for communications satellites, and offers a compromise between on-board and ground based processing. The on-board switch interconnects cellular (spot) beams, either on a semipermanent basis or possibly dynamically with the switch locked to a ground based TDMA timeframe. Beams would re-use frequencies and polarisation to make efficient use of the spectrum. This is still a transparent payload, since no demodulation is performed. However, although RF switching is a possibility, OBP offers a better solution for HAPs.

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HAP

Transponders, on-board modulation / demodulation and processing enabling switching between beams

Figure 13: Single HAP, multiple beam antenna with on-board processing (on-board modulation and demodulation). 4.2.1.4 Multiple interconnected HAPs Figure 14 illustrates a multiple-HAP network. The HAPs could be interconnected with radio links, perhaps at V-band, because the HAPs are above rainfall that causes the most serious link fading. However, optical links, offering large bandwidth and free spectrum, are more likely to be used to interconnect HAPs. It would not be necessary to connect each HAP individually to a backhaul because the backhaul route for some HAPs could be provided via the optical inter-HAP connections. Connecting HAPs in a mesh arrangement with alternative backhaul routes could provide a degree of resilience. In Figure 14, a four-HAP network is considered. The coverage areas do not necessarily overlap (perhaps because the HAP network covers a dispersed island group). In the example, a line of sight between HAP1 and HAP4 does not exist because of the curvature of the earth. HAPs 2 and 3 both offer connection to the terrestrial core network. This type of network assumes on-board processing.

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HAPHA 2 (core P connectivity)

Inter HAP optic links

HA P 4 HAP

HA HAP P 1

HA HAP P 3 (core connectivity)

Figure 14: Multiple HAP network connected by optical links

4.2.2 Ground topology 4.2.2.1 Point to point private circuits Point to point broadband connectivity can be provided as a part of the core network, or to link one network with another. Sometimes, customers request Telcos to provide a transparent data pipe (e.g E1, E2, E3, SDM-1, T1 etc.), between two customer locations. These private circuits can be supplied terrestrially using copper or fibre. Most Telcos offer customers private circuits at a range of data rates with defined interfaces. Typically, private circuits are used by corporate enterprises to carry data between two points, e.g. head office and a branch office. Private circuits simply transmit data from one end to the other without modification. It is for a third party to determine the type of data carried by the private circuit. Typically, a Telco will install a high-speed data pipe between a customer interface and the core network. A similar pipe will be installed at the other end of the link, between the core and the second customer interface. These access data pipes can sometimes be expensive to provide because coaxial cable or fibre must be installed. Cable ducts may not exist in rural areas, and significant work may be involved. Satellites are sometimes used to provide high-speed private circuits, but they are only truly cost effective within areas of poor terrestrial infrastructure, or over long distances, or when a temporary private circuit is required. Additionally, the unavoidable satellite delay may adversely affect some applications. HAPs could be used to provide a high-speed point to point data link between the two end points. In this case, the link is independent of the terrestrial network, but both end points must be within the coverage beam of the HAP, or the HAP constellation. Alternatively, the HAP could be used to connect just one end point into a core network. 4.2.2.2 Broadcast Broadcast is efficiently carried by most radio systems. A good analogy to a potential HAP service is satellite TV, which enjoys a wide European market to cheap domestic receivers. HAPs will find it 29th Jan 2004


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difficult to compete in the broadcast TV market unless terminal equipment can be similarly competitively priced, or there is some service differential, for example targeting programming at the regional / local market. Terrestrial DVB is another competitive technology to HAPs which can also be targeted at a regional market, e.g. within the range of a particular terrestrial transmitter. Broadcast TV entertainment does not normally require a return channel, although a low data rate return is sometimes useful for interactive TV and for remotely interrogating and configuring terminal equipment. It is apparent that terminal equipment can be simpler and cheaper if a transmit capability is not provided, so a HAP service could use a terrestrial PSTN return in a similar vein to the UK Sky TV service, where this is considered desirable. However if a radio based return link is necessary, a HAP system will provide a lower cost return link than is possible with satellite (subject to terminal costs etc) and this would have the advantage of being “always-on”. DVB-S equipment for satellite is now commonplace within Europe. It might be worthwhile for HAPs to take advantage of the commonality and low pricing of satellite IRDs (Integrated Receiver Decoders) in any service offering. The HAP frequencies are likely to be different to those of DVB (currently specified at Ku-band), but the same L-band interface to the IDR could be used. An interesting observation is that the MPEG-2 standard, which is a part of DVB, is less efficient than many more modern derivatives, so the advantage of using common IRDs must be reviewed nearer to a HAP system launch date.

Conventional satellite IRD

HAP ODU L-band interface

Figure 15: User Terminal Interface for DTV 4.2.2.3 Point to Multipoint Service The terms point-to-multipoint, narrow-casting and multi-casting all loosely represent a “broadcast” to selected receivers within the coverage area. Some services must be delivered and played out in real time, for example live TV, a football match, a lecture / business TV programme that has a return link for live questions. Other services can be loaded onto a storage medium at the customer premises (or on a HAPs) and played out at a later time, for example VoD. IP multicast can be used to deliver the same files (content) to multiple selected sites without the need for return links. This method uses multiple sends to (virtually) ensure content delivery of all sites. The architecture already used by a number of manufacturers (e.g. [44]) for satellite would also be suitable for HAPs. The content delivery method requires bespoke software to be loaded at each receiver. This controls file storage and readout, and perhaps a file delivery confirmation mechanism. Specific files can be sent from the Hub to authorised groups of receivers. As an example, a file intended for delivery to a specific group of sites may be broken into a number of segments, each with a check sum. Each authorised receiver is therefore able to detect which, if any, segments have been received in error, perhaps as a result of a rain fade. Different receivers may have received different segments in error. Each receiver stores the correctly received segments and awaits a second send of the entire file, perhaps sent some hours later. In this second send, the receiver collects those segments not acquired in the first send, assembles and stores the file. There may be two or three sends of each file, depending on the QoS required. Often, although these file delivery systems do not require an on-line return channel, mechanisms are in place to check data transfer, e.g. that all files sent to a particular location have been received. Sometimes this requires a PSTN dial-up from sites that have a file delivery problem. 29th Jan 2004


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Current content delivery multicast via satellite equipment tends to encapsulate IP datagrams within a DVB multiplex. It is more efficient to fill a satellite transponder with one large DVB carrier rather than with multiple carriers that would require a power back-off because of inter-modulation effects. The IP multicast (and other IP data), can share the DVB multiplex with other programmes, e.g. DTV, and derive a link budget advantage. The same would be true for HAPs, if the same conditions were to apply and this is recommended for further study. Encapsulating IP within DVB also enables the application to take advantage of the low cost and high availability of DVB satellite receivers, however DVB was not originally designed for carriage of IP and hence is not highly efficient. However, there is work going on to improve this within the IETF for Kuband satellite (within the IP-DVB BoF) which could be adopted, but this needs checking since any advantages may not hold true for HAPs that will operate at Ka- or V-band. 4.2.2.4 Multiple access, Star and Mesh Configurations A HAP network will require a method of controlling all transmissions from both ground terminals and HAPs such that they do not cause interference, either to each other or to other users of the radio spectrum. The type of applications and services that can be carried is more heavily dependent on the HAP configuration, e.g. transparent transponder or on-board processing, than on the access method (star or mesh). ETSI define Star and Mesh networks as follows [3]: A Star network topology is defined by the star arrangement of links between the Hub station (or Gateway) and multiple remote stations. A remote station can only establish a direct link with the Hub station and cannot establish a direct link to another remote station. A Mesh network is defined by the mesh arrangement of links between the stations, where any station can link directly to any other station. The star topology can be considered as one special case of the mesh topology. A Star topology can be used to provide Mesh connectivity by establishing an indirect link between remote stations via the Hub station. Thus, a Star configuration (Figure 16) suggests the use of a transparent transponder. All transmissions are routed through a Hub ground terminal, which controls all transmissions. Direct communication between two user terminals via the HAP is not possible. Communication between the two user terminals would need to be routed via the Hub. The Hub terminal would also normally provide connectivity into the core network, and would tend to be larger and more robust than the user terminals. A user-terminal to user-terminal link will involve two hops to the HAP, e.g. a 90 km minimum propagation path. Although this will have a small impact on delay, it is unlikely that this will affect services and applications. Star connectivity also has link budget advantages in that user terminals only operate directly to the Hub so there is an opportunity to reduce the multiple user-terminals sizes and costs by providing a larger (single) Hub ground station facility.

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User terminal

Hub ground terminal

User terminal

User terminal

User terminal

HAP (transparent transponder)

Hub ground terminal

User terminal

User terminal

User terminal

User terminal

Figure 16: Star configuration A Mesh configuration allows direct communications between user terminals. A mesh configuration can be used with a transparent transponder, and Mesh is the obvious configuration if the HAP incorporates on board switching and spot beams. In this latter case, switching can be at the ground, on board the HAP, or distributed. 4.2.2.5 Ground Terminal Configuration HAPs ground terminals should provide the following inter-working functions (based on ETSI standards for satellite terminals): • HAP Access Function (via User Terminal): the logical function that provides interworking between the HAP bearer service and an End System, either directly or via a local network (e.g. a LAN); • HAP Gateway Function (via Gateway Terminal): the logical function that provides interworking between the HAP bearer services and a core network, either directly or via a transit network. These logical definitions only define the types of interworking function provided by a terminal. A given HAP terminal may provide multiple instances of both access and gateway functionality. A User Terminal is defined as a HAP Terminal that provides at least one instance of access functionality.

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Similarly, a Gateway Terminal is defined as a HAP Terminal that provides at least one instance of gateway functionality, even if it also contains access functionality. The User Terminal is especially price sensitive for services aimed at domestic consumers, such as broadcast TV, multicast entertainment, VoD and broadband Internet. Business customers will tolerate higher costs for the right types of services. There is a wide range of devices for delivering/sending digital content to/from the home coming to market or planned, and a similar wide range of services proposed to connect them. There are also several competing standards bodies aiming to provide the means of making them all work together. These include universal plug-and-play (UpnP) based on Web pages and XML and home audio visual interoperability (HAVi), a java-based system. Other bodies include the Digital Home Working Group, the Open Service Gateway Initiative (OSGI), and the Internet Home Alliance [46]. The biggest technical challenge facing these organisations is how to connect the PC to the living room. Many of broadband’s potential benefits and new applications depend on combining media viewing and listening with the PC’s strengths for Web surfing and communications. The cheapest type of user terminal antenna for Ka- and V-band is a receive-only fixed reflector (parabolic or offset parabolic). Costs increase if the user terminal is required to transmit, which is a requirement for customers wishing to send broadband data. It should be noted that the PSTN or ISDN can be used as a return channel for asymmetric data types, although the desirable “always-on” feature for Internet would be lost. A user terminal transmit facility will also need to be regulated to avoid interference from and into other radio systems. The cost of the user terminal will rise if tracking of the HAP is required. The necessity for tracking will depend on both the station keeping of the HAP and the user terminal antenna beam-width. Future generation user terminal antennas may be phase arrays. The user terminal configuration for Ka- / V-band HAPs is likely to mimic that of existing satellite terminals. User equipment, e.g. PC or TV, will plug into an Indoor Unit (IDU) using standard interfaces such as Ethernet, USP, RS449/422, SCART, etc. The IDU will include the modulator and demodulator and up- and down-converters. It will be connected by cable to a rooftop or outside wall mounted Outdoor Unit (ODU). The interface between the IDU and ODU will probably be at L-band. The ODU will contain the antenna and feed, LNB and SSPA (Solid State Power Amplifier).

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5. POTENTIAL APPLICATIONS AND SERVICES FOR HAPS 5.1 Traffic Classes The ETSI Definition for traffic classes states that a traffic class is a generic concept that applies at every step of the traffic flow. In other words this corresponds to the characteristics of the end-to-end service. The traffic class is defined by a set of general characteristics. Four traffic classes can be distinguished in HAPs broadband networks, based on the traffic classes defined in TS 123 107 [12] (see Table 4), with the traffic characteristics given in Table 5.

Table 4 : Traffic Classes TRAFFIC CLASS Conversational

INTENDED USAGE Real-time conversational traffic involving conversing entities

Streaming

Real-time streaming traffic involving the sending of information from one entity to another Near real-time interactive traffic involving retrieving of information by one entity, from another entity Non real-time background traffic involving the sending of information from one entity to another entity

Interactive

Background

EXAMPLE APPLICATIONS telephony, teleconference, videophony and videoconference, chatting, netgaming audio and video broadcast, surveillance web browsing

Email and file transfer

Table 5 : Traffic Characteristics Traffic class Conversational

Streaming

Interactive

Background

Components Speech Audio Video Data Multimedia Audio Video Multimedia

General traffic characteristics Constant Rate (CR) and Variable Rate (VR) Delay sensitive Delay variation sensitive Limited tolerance to loss/errors (depends on coding) Variable Rate (VR)

Data

Tolerant to delay (buffering in terminals) Delay variation sensitive (depending on buffer sizes in terminals/gateways) Limited tolerance to loss/errors (depends on coding) Variable Rate (VR)

Data

Delay sensitive (but more tolerant than conversational) Tolerant to delay variation Loss/error sensitive Best Effort (BE) Not delay sensitive Tolerant to delay variation (and more tolerant than interactive class) Loss/error sensitive

The main distinguishing factor between the four traffic classes is the sensitivity of the traffic to delay. Unlike satellite, which has the essentially same traffic class structure, the propagation delay via HAPs is not significant. The Conversational class is meant for traffic which is most delay sensitive while the Background class is the most delay insensitive. Conversational and Streaming classes are mainly intended to be used to carry real-time traffic flows.

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Conversational real-time services, like video telephony, are the most delay sensitive applications and those data streams should be carried in Conversational class. Interactive class and Background class are mainly meant to be used by traditional Internet applications like WWW, Email, Telnet, FTP and News. Due to looser delay requirements (when compared to conversational and streaming classes) these classes may provide better error rate by means of channel coding and retransmission. The main difference between the Interactive and Background classes is that the Interactive class is mainly used by interactive applications, e.g. interactive e-mail or interactive web browsing, while the Background class is meant for background traffic, e.g. background download of e-mails or background file downloading. The responsiveness of the interactive applications can be improved by separating interactive and background applications. For example, if traffic in the Interactive class is allocated a higher priority in scheduling than Background class traffic, so background applications use transmission resources only when interactive applications do not need them.

5.2 HAP Scenarios of Operation and Services The FP5 IST HeliNet project [10], [49]. [50] identified two possible scenarios of HAP operation: •

Providing applications/services on a long-term basis to SME and residential users

•

Providing broadband communications for short-term applications such as disaster relief.

The four priority broadband payload services identified in the HeliNet task T1 report were: •

Internet access

•

Video on demand

•

Video conferencing

•

Voice telephony.

The broadband user-group market comprises: •

•

Business o

Corporate Enterprises

o

SOHO/SME

o

Teleworkers

Residential o

Entertainment services

o

Information services

•

Government (including EU, national and regional)

•

Military

A service/application set can be derived for each user group, including delivery to both fixed and mobile (vehicle and backpack/hand-held) users. The list is exhaustive, and not all services and applications are applicable for study within the CAPANINA project. The procedure used is to first list all potential services and applications, then to consider in more detail those applicable to CAPANINA (e.g. omitting narrow-band, military, UMTS and optical services). Finally, we derive a commercially viable service set and indicate which applications should be considered for the CAPANINA test programme.

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A comprehensive list of potential services and applications follows: •

Point to point high data rate private circuits

•

Communications at temporary venues (disaster sites, Olympics, etc.)

•

Overlay of terrestrial data links for resilience (link failure recovery)

•

W-LAN hotspot backhaul

•

W-LAN on trains and coaches (backhaul)

•

Voice

•



Telephony



Voice over IP

Internet 

•

Intranet 

•

•

•

Broadband access to company Intranet services and applications

File transfer 

•

Broadband access to all Internet services and applications

FTP

Entertainment 

Radio and TV broadcasting



Video on Demand



Gaming

Distance learning 

To universities



To schools



To business



To home

Telemedicine (for teaching and assistance) 

Intra-hospital



To disaster sites



To developing countries

•

Communications to emergency service fixed & mobile users (Police, Fire, Medical, Rescue)

•

Communications at disaster sites (e.g. earthquakes, floods)

•

Communications at temporary venues (e.g. Olympics)

•

Surveillance, video and infrared, and remote monitoring and control 

•

Although surveillance is a valid application for HAPs that could include a broadband element, e.g. backhaul, it is outside the theme of CAPANINA, but see Appendix 1 for an overview.

UMTS HAP base station provision  Although UMTS is a valid application for HAPs that could include a broadband element, e.g. backhaul for a base station, it is outside the theme of CAPANINA, but see Appendix 2 for an overview.

From this list, we expand on HAPs applications and services for potential study within CAPANINA, as follows.

5.3 Broadband Internet Broadband Internet access is a key application for both business and domestic users.

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5.3.1 Broadband Internet for Domestic Users Access to the Internet at broadband speeds is a key application for domestic users. There is a growing market for asymmetric Internet activities such as Internet surfing and file downloads, but also for symmetric peer to peer usage such as the exchange of music, photographs or video files. Internet applications for domestic users are numerous and growing, for example: •

Email

•

Home banking

•

Home shopping

•

Information and booking services, e.g. travel/hotel/theatre

•

News

•

Entertainment

•

Encyclopaedia

•

Hobbies

•

Web page hosting

•

Etc.

The experience of many of these applications can be enhanced by broadband access, especially those with a video content. Terrestrial ADSL is now available to many citizens throughout Europe. Copper pairs in the access network, originally designed for telephony, are used together with sophisticated technology to enable broadband data rates at competitive prices. However, many European citizens are unlikely to gain access in the foreseeable future because they either live in rural locations or in countries that are not aggressively rolling out ADSL. HAPs are independent of the terrestrial access network, and have the ability to provide much higher data rates that is currently available via ADSL (although not VDSL). The broadband experience is therefore enhanced, allowing a richer mix of multimedia content, higher video quality, enhanced gaming, etc.

5.3.2 Broadband Internet for SME and SOHO Terrestrial ADSL is now available to many SME (Small to Medium Enterprise) and SOHO (Small Office, Home Office) users throughout Europe. However: •

Many locations, especially in rural areas in new EU member states, are not yet served

•

ADSL data rates are limited by the distance of the user from the exchange DSLAM

•

True high speed broadband, e.g. greater than 2 Mbit/s is not available via ADSL

HAPs are independent of the terrestrial access network, and have the ability to provide higher data rates than are currently available via ADSL.

5.4 Broadband Access to Company Intranet Companies with offices/facilities at dispersed locations often require common access to a company Intranet. This is usually protected by a firewall. Although some locations may be able to gain terrestrial broadband access, other locations may not. Even where ADSL is available, access to the Intranet may be required at higher data rates than can be accommodated by ADSL. An important issue is security. Traffic must be able to pass through Firewalls. 29th Jan 2004


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HAPs are independent of the terrestrial access network, and have the ability to provide higher data rates than are currently available via ADSL. Applications include: •

Email

•

Document access

•

File transfer (FTP)

•

Application sharing

•

Business Television

5.5 Videoconferencing The HeliNet project identified videoconferencing as a specialist service targeted at SMEs, and assumed a down-link of 3 Mbit/s. This is a compromise between a minimum of 1.5 Mbit/s and a maximum of 6 Mbit/s, as specified in the ETSI BRAN standard [11]. Assuming a maximum cell rate of 18 Mbit/s for video conferencing (as suggested by the HeliNet project), this would enable 6 (both-way) channels per cell. However, the videoconferencing situation is conducive to powerful video coding because the picture does not tend to vary significantly between frames; the background remains the same and the attendees are usually sitting and exhibiting little movement. Significant advances have been made in video codecs recently, for example a 384 kbit/s link can give good performance and can be configured terrestrially using DSL or a three line ISDN. A number of service providers offer managed world-wide videoconferencing services. It would be of benefit for HAP enabled customers to be able to join such conferences.

5.6 Entertainment Entertainment is probably best targeted at domestic consumers, although there may be a market for delivery to other venues, e.g. cinemas, public houses, etc. Entertainment can be delivered via the Internet (e.g. Internet Radio, video streaming), or it can be delivered outside the Internet (e.g. DVB delivery of satellite/terrestrial radio/TV). Video programming in particular benefits from a broadband delivery system. Entertainment (and indeed multimedia) delivery by HAPs to a fixed location would require an antenna at the user’s premises with a line of sight view of the HAP. In this respect, the indoor equipment would be similar to that required for satellite delivery. The business case for HAPs suggests a two-way platform. This requirement for a transmit capability from the user terminal increases complexity and cost, and also regulatory and safety issues. Current consumer entertainment broadcast systems, terrestrial and satellite, are low cost, and universally available, for example via satellite. A HAP delivered entertainment system must be cost competitive, or offer something extra.

5.6.1 TV and Radio TV and radio are essentially broadcast services, although interactive TV may eventually gain more credibility with users. Broadcast TV and radio from HAPs would require simple, low-cost, receive-only user terminals. Where two-way user terminals are provided, e.g. for broadband Internet, entertainment TV and radio can be useful value-add services, providing an attractive total package to potential customers. HAPs could provide TV distribution, although the business case is affected by competition from satellite and terrestrial TV distribution. Digital TV and radio broadcasting from satellite is well established throughout Europe using DVB, with widely available, low-cost receivers. However, current generation satellite footprints for TV cover vast areas of Europe, so the transmission of local or 29th Jan 2004


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regional content is less efficient. Digital terrestrial broadcast TV is also competitive, and offers regional coverage. The advantage of HAPs is the small footprint of the spot beams, although future generation satellites will also use spot beams. HAPs could provide television to isolated rural areas, or to small countries, or to island clusters. Digital TV for a whole region could be offered at a stroke. Thus, there may be a market for HAPs in delivering local or community television, as in the USA. We would need to consider •

Frequency allocations

•

Regulation

•

User equipment costs (must be competitive with other offerings to consumers).

Community TV could be directed at buildings or small communities, e.g. campuses, industrial sites, apartment blocks, etc. Another opportunity is for HAPs to deliver content to local terrestrial transmitters. In this scenario the user can use a standard TV set and (UHF) aerial, so the user would not require HAPs-specific equipment.

5.6.2 Video on Demand HAPs, with its superior link budget, small cellular structure and frequency re-use, is better positioned for cost competitive point to point links than satellite. VoD, if the right programming can be provided at a competitive price, offers tremendous growth potential. VoD is highly asymmetric in terms of data rate. Requests could be made via dial up PSTN, followed by an on-line delivery of the video programming. This would enable a cheaper, receive-only user terminal. The big issues are the location of the high-cost servers and content, and the impact on the back-haul. There is also a choice to be made between a live service, whereby a user requests a real time download and play out on his equipment (TV), and a download of VoD content to a storage medium at the user’s premises that can be played out at a later time. The HeliNet project proposed a user data rate of 3 Mbit/s, based on a compromise between a maximum of 6 Mbit/s and a minimum of 1.5 Mbit/s as specified in the ETSI BRAN standard [10],[11]. A maximum bit rate per cell of 36 Mbit/s would allow 12 channels to be maintained for VoD. It should be noted that advances in video codecs could mean that lower data rates might be acceptable to users. The VoD system envisaged in HeliNet task T1 suggested that subscribers would have the option to select films from an extensive library, but may sometimes prefer to select films from a more limited range of popular films, chosen by the service provider. The provider could download these popular films to the subscriber during quiet times. Such a system allows some degree of flexibility in the traffic management of the service. The film library option represents traffic that must be downloaded in near real time, whilst the limited selection option represents cached traffic. The HeliNet project estimated the ratio of cached-to-download traffic at roughly 20% [10].

5.6.3 Gaming Gaming is growing in popularity with a dedicated following of gamers. The games are becoming more sophisticated with increasing speed requirements. The symmetrical nature of data rates is not fully met by ADSL, although it is by DSL, and the delays introduced by satellite are sometimes unacceptable. HAPs offer a potential solution.

5.7 Distance Learning Distance learning is a very useful application: 29th Jan 2004


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•

To universities

•

To schools

•

To business

•

To home


There are two basic distance learning formats, a live session and an interactive course. The live session is basically a lecture that is broadcast live to all students. A return channel is provided to enable students to ask questions, provide their answers to tests, etc. The data exchange requirement is therefore asymmetric. The lecture would be sent from the source, e.g. a university, either directly to the HAP via a user terminal, or perhaps more likely via the core network to the HAP up-link. Students would receive the lecture from the HAP via their own user terminals and either return data via their HAP terminal or via the terrestrial PSTN. The Data rate requirements in the multicast direction (lecturer to students) would be analogous to those used for video conferencing using modern compression techniques, e.g. in the order of 300 kHz to 1 Mbit/s. This would suffice for a view of the (moving) lecturer and a static background. Teaching aids, such as whiteboard, PowerPoint slides, photographs, video clips, etc. could also be multicast to students, and some of these applications might require more bandwidth. The equipment necessary for a lecture at the user (student) premises would almost certainly be a PC connected to a HAP user terminal to receive video streaming. The returns from students to lecturer could be simply audio, but value would be added if a PC link could be established, enabling text and whiteboard return, webcam, etc.. HAPs would enable higher data rate applications in the return path, but the cost of these applications (hardware and software) at the student premises must be taken into consideration. The Interactive course is a structured leaning method whereby the student is taken along a learning path often tailored to his needs. Progress is checked by means of tests, the results of which determine the path then taken. There are many examples of interactive courses on the Internet. The advantage of broadband is that a more media-rich content can be accessed without the penalty of excessive down-load times. Distance learning could be of significant social benefit, to citizens unable to attend a regular university requiring full time attendance. The Open University (OU) in the UK is intended for such people, often mature students in full or part time working. OU students could benefit significantly from the use of broadband distance learning techniques, as could students in developing countries. Universities could host lectures on specialist subjects to other universities, colleges and schools.

5.8 Telemedicine (for teaching and assistance) Telemedicine is a very useful application: •

Intra-hospital

•

To medical practices and community health centres

•

To disaster sites

•

To developing countries

In the teaching scenario, the mechanism is much the same as for distance learning. Students are able to view a live operation or diagnosis, and are able to ask questions via the return channel. In the assistance scenario, a medical Doctor/Nurse at a remote location is able to send live audio/video material of an incident or an operation to a consultant specialist. The consultant has a return channel and can offer advice or assistance. The potential uses of telemedicine are wide ranging. The analogy with distance learning extends to medical course downloads and access to stored medical diagnostic information. Some of this information could be made available via a medical Intranet or to citizens via the Internet. In fact, this type of information is already on the Internet, but a broadband connection would enable a much richer content.

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There is a requirement for high quality video in these applications, so even with state of the art video compression coding techniques, data rates are likely to exceed those used for videoconferencing.

5.9 Disaster site communications and services HAPs could be rapidly deployed, and could therefore provide rapid and high quality services at disaster sites. HAPs could provide a range of communications links between the emergency services medical, rescue, fire, police) at the disaster site, and broadband connection into a core network. It should be noted that a disaster is likely to seriously overload the incumbent Telco, whose infrastructure may be damaged by the event. This may prevent a timely interconnection of the Hub gateway into an international core network, in which case a HAP to satellite link could be considered. The broadband applications and services would include Internet / Intranet, telemedicine, video conferencing, etc. Broadband communication to the emergency services could also open up new avenues for assistance from a base station. For example a fire or rescue crew could send a live video information to a base station and receive assistance on how best to deal with the emergency. An ambulance crew could send video footage of a particular injury and similarly receive assistance. The police could send live video footage of an incident to their base, etc.

5.10 Communications at Temporary Venues (Special Events, Olympics, etc.) HAPs can be used for the provision of communications at special events requiring a temporary communications infrastructure. Temporary large gatherings of people requiring (broadband) communications can result in an overload of the normal communications infrastructure. HAPs could provide a solution to this exceptional peak traffic. Although a HAP can readily be deployed to a new location, the requirements of the ground segment must also be considered. In particular, provision must be made for the backhaul. This will normally require a radio link between the HAP and a ground station connected into the core network. However, it would also be possible to provide a link into the core via satellite, with a direct line of sight link between the HAP and a satellite. In some respects, this scenario is similar to the provision of communications at disaster sites. In addition to UMTS services that could be provided by HAPs (outside the remit of this report – but see Appendix 2), broadband Internet is an obvious service requirement, together with communications for the media (radio and TV feeder links, etc).

5.11 Overlay of Terrestrial Data Links for Resilience (link failure recovery) Terrestrial networks can have many nodes. In the event of a link failure between nodes, e.g. a damaged fibre or cable, service can often be restored by adopting an alternative route. A HAP could also be used to restore service by providing a private circuit replacement for the damaged link. It is unlikely that more than one terrestrial cable would fail at any one time, so the capacity of the HAP need only be sufficient to provide perhaps one duplex 155 Mbit/s connection. The bandwidth reserved for the terrestrial overlay could be used on a pre-emptable basis for other services during normal (non-failure) operation of the protected network. During these times, the HAP could complement a terrestrial link in providing for short periods of high intensity traffic on any particular link. Alternatively, the reserved HAP capacity could be used for any pre-emptable service. Satellite could also provide this type of overlay network, but the significantly lower propagation delay of HAPs is more likely to meet the overlay network specification.

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5.12 Wireless LAN Hot Spot Backhaul W-LAN hotspots are now well established within Europe, offering high-speed, secure internet connection, making it possible for users to use their laptops or PDAs to access their corporate intranet, send and receive e-mails and browse the web. W-LAN hotspots are based on the "WiFi" public wireless LAN standard, and include motorway service stations, roadside rest areas, airports, railway stations, conference centres, hotels and cafes. The W-LAN base-station sends and receives broadband data (typically up to 11 Mbit/s for 802.11b and up to 54 Mbit/s for 802.11g) to the user PC at a radio frequency of about 2.4 GHz., typically over distances up to 100 metres. The base stations are in turn connected to the Internet. The standard is the same IEEE 802.11b Wireless LAN protocol already employed in offices and homes where fixedwire solutions are hard to install or insufficiently flexible. HAPs offer a method of providing broadband connectivity to base-stations at potential W-LAN hotspot sites that cannot be economically served by a terrestrial connection. Such sites might be in remote areas, e.g. roadside cafes or service stations. The opportunity for HAPs is in providing the backhaul connection between the W- LAN base-station and the core network. In practice, the HAP is acting as a private circuit between the W-LAN and the Internet.

5.13 Wireless LAN on Trains and Coaches (backhaul) Broadband communications to vehicles and trains is a particular study area for CAPANINA. Train passengers, especially business travellers and commuters, could more effectively use their time if broadband access to the Internet and company Intranets could be provided. Similarly, many commuters often use their travelling time productively by working on the journey. Internet/Intranet access can be achieved via a mobile telephone within Europe, but in many cases the service is unsatisfactory because of low speed and poor coverage. The advent of 3-G mobile will improve this situation, but true broadband will not be provided and there will still be gaps in coverage in European many regions. Train operators in see a market in the provision of a broadband W-LAN within certain compartments of the train. The target market in the first instance is the business traveller with a Laptop PC. However, there could also be a requirement for video broadcast/multicast to video screens within train compartments. Additionally, other information services applicable to travellers and entertainment/advertising could be provided. Broadband services to motor vehicles must not distract the driver’s attention or otherwise compromise road safety. However, specialised road traffic services could be envisaged, and broadband Intranet/Internet would be useful to business travellers when parked. HAPs could support broadband W-LAN on trains and coaches by providing the two-way backhaul to the core network. The services would be similar to those made available through W-LAN hot spots. Additionally, there is scope to provide streamed entertainment, news feeds, travelling information and advertising. The service is likely to be provided using mm waveband carriers. This will require a tracking antenna on the train, and a QoS mechanism to support line of sight blockage as the train passes though tunnels cuttings and covered stations. This is a particular area for study, and could involve caching, predictive HAPs tracking on trains (from knowledge of the geographical position and the orientation of the railway track) and access to alternative, lower rate (e.g. GSM, UMTS) services during outages.

5.14 UMTS HAP Base Station Provision The CAPANINA project is aimed at broadband applications using mm frequencies. This precludes a study of direct communication from the HAPs to UMTS handsets. Any CAPANINA association with UMTS is therefore limited to a backhaul between a cellular transmitter/receiver and central base station electronics. For more information on potential UMTS applications, see Appendix 2.

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5.15 Broadcast Based Broadband (B3) Broadcast Based Broadband (B3) is a service concept that can be applied to HAPs. The objective is to use the inherent broadcast / multicast advantage of HAPs to deliver popular web content to all users. Multicast data would be stored on a suitable storage medium (e.g. hard drive) for later access by the user. One advantage of B3 is that the user experience is enhanced because he has instant access to the application at high speeds directly from his storage medium. Another advantage is that the available bandwidth on the HAP is used efficiently because it reduces the amount of Unicast traffic form different users requesting the same information. B3 is not yet a product. There are a number of issue to be considered, including: •

The need for web content re-purposing since interactive web pages are not suited to a broadcast delivery and an off-line viewing environment.

•

The issues surrounding how to effectively capture advertising statistics for offline services.

•

Generation of electronic programme guides, carousels, queues and traffic prioritisation to make the most efficient use of available satellite capacity. Especially considering the delivery of popular Internet content, Audio/Video content and popular file downloads.

•

Hub and user terminal support for simultaneous multiple transponder reception.

•

Trade-off between reliability, additional coding and retransmissions.

•

Digital Rights Management, Billing and Usage Statistics.

•

CPE Architecture.

•

5.16 Military Applications Military applications of HAPs are wide-ranging, and include communications and surveillance of all types. AWACS (Airborne Warning and Control System) is an early example of HAP, and military applications are likely to form some of the first applications of the type of HAPs described in the HeliNet project. However, military applications and frequencies are outside the scope of CAPANINA project.

5.17 Third World Applications Like satellite, HAPs are likely to prove very useful in areas of poor terrestrial communication. Third world / developing country governments may prefer HAPs to satellite in some situations because: •

Governments appreciate control over communications. HAPs are significantly cheaper than satellites, so developing countries may be able to afford HAPs whereas satellite control is beyond their reach.

•

In addition to a communications payload, governments are also interested in surveillance payloads for police and military applications.

•

Superior link budgets can be achieved over regional / local areas

Services and applications are as already described, namely broadband Internet/Intranet, broadcast entertainment (e.g. TV), telemedicine, distance learning, etc.

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6. Issues with Third Party Applications and Service Providers 6.1 Roles, Players and the Value Chain Framework The players and roles, based on ETSI definitions [5], are: HAP Operator: operator responsible for the bulk transport services of the HAP(s). The HAP operator provides a defined set of bulk transport services to the network operators. The HAP operator is assumed to own the HAP and be responsible for telecommand, telemetry and control. HAP Network Operator: operator responsible for his subset of the HAP resources. The network operator may obtain resources from multiple HAP operators and may combine these with other network resources to provide a broader network service to the service providers. Terrestrial network operators: there may be several of these that together provide the end-to-end path for the user communications. Service Provider: holds the service level agreement (or service contract) with the subscribers. The service provider may obtain services from multiple network operators (including one or more HAP network operators) and in order to offer a combined service to the customers. Arrangements with other service providers will be made to provide additional services and applications in order to provide one-stop shopping for the subscriber. The service provider is responsible for all aspects of the customer service from installation, to maintaining the quality of service during normal operation, to billing the customers for network usage. Subscriber: entity that enters into a service contract with the service provider. A single subscriber may support one or several users with a single contract (e.g. a large company subscriber may subscribe for services to several hundred users). User: entity that uses the network services provided by the service provider. The user is associated with a single subscriber and the user's network usage is subject to the service agreement between that subscriber and the service provider. Figure 17 illustrates the interaction of these roles.

User

Subscriber

Other service Providers

Service Provider

HAP Network Operator

Network Operator

Network Operator N

etc

Other Network Operators

HAP operator Service provision Payment Network provision (access and / or core) Payment Provision of infrastructure and readiness for fulfilment Payment

Figure 17: Roles within a HAP Network

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6.2 Reference Frameworks There are several business process frameworks produced by industry forums such as TINA-C [20] and the Telemanagement Forum (TMF) [21]. Most of them are connected with Operational Support Systems (OSS) and they have varying degrees of support from communications companies, systems integrators and software vendors. The framework that has the largest amount of development and support is the enterprise Telecoms Operations Map (eTOM) from the TMF. The TMF has issued several documents describing this map, e.g. [22], and the top-level map is repeated here as the righthand side of Figure 18.

Customer Strategy, Infrastructure & Product

Customer Operations

BM

Market, Product & Customer Market, Product and Customer

SM

Service

NM

Resource (Application, ComputingResource and Network) (Application, Computing and Network)

EM

Supplier/Partner

NM = Network Management EM = Element Management

Supplier/Partner

Supplier/Partner Suppliers/Partners

BM = Business Management SM = Service Management

Service

Enterprise Management

Shareholders

Employees

Other Stakeholders

©TeleManagement Forum October, 2001

Figure 18: Reference Frameworks On the left-hand side of Figure 18 is the well-known ‘pyramid’ from the Telecommunications Managed Network (TMN) from the ITU-T recommendation M3013. The TMN was the first framework, but it lacks sufficient detail to allow implementation across several vendors. Figure 18 shows the association of the eTOM to the TMN pyramid. The network, which may include a HAP link, is managed by the enterprise management layer; this is called ‘element management’ in some frameworks. This is where the network elements such as switches, routers, and even HAP payloads are managed. The protocols used at this layer are typically Simple Network Management Protocol (SNMP) between the element managers and management agents within the elements. Above the enterprise layer is the resource layer, mapped across to network management. In this layer, a database holds the topology of the network (the maintenance of which is not trivial), with rules to cope with congestion and fault conditions. The service management layer is centred around a database that maps services to network resources in the downwards direction and maps services to customers in the upwards direction. Intelligent service functions reside at this layer, such as automatic session set-up and pricing of resources. The service layer will communicate with service layers in other network stacks to facilitate ‘one-stop shopping’ where a service provider contracts with a customer to manage his entire portfolio. This communication link is along an X ‘co-op’ interface defined by TMN using the Q3 interface that employs the CMIP management protocol [24]. This is one main way in which services on one network can be automatically procured and monitored by a third party service provider. The other main way is to use an API such as that developed by the Parlay group (see next section).

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The business layer is the part of the system that interfaces with the customer and consists of order handling, fault reporting, service-level agreement policing, help desk and a data base of customer details, their equipment service records etc. All of these layers are relevant to the CAPANINA project. Applications and services are ordered by the customer and are defined and managed at the service management layer. This layer makes requests on the various network segments to provide connectivity and one or more of these segments could be a HAP link. The network manager takes care of the dimensioning and control of major routes. This is a management plane ‘downward’ flow. An example of an ‘upward’ flow would be when a fault occurs on an element, whereby the element manager reports it to the network manager layer where the impact of the problem is minimised. Then it is reported to the service management layer for assessment of the impact on the services and on the customers affected. Then it is reported to the business layer for action on the service level agreements and billing. Thus it can be seen that management plane flows are generally vertical. Signalling (control plane) flows are, in contrast, usually horizontal because set-up messages and QoS requests flow from one network segment to the next. Figure 19 shows the general idea.

User

User

Service Provider

Network Operator 2

Network Operator 1

Other service Providers

Network Operator N

Other Network Operators

Other agreements (eg equipment and software maintenance)

OSS (service management) functions Signalling

Figure 19: Management and Control Plane Flows In Figure 19, management plane flows are vertical and signalling flows are horizontal The networks shown in Figure 19 can be owned by different organisations, and they do not want to share OSS information. It is a political minefield when one network requests performance parameters and fault information from another and this has never been agreed. So the only interfaces that have been successfully standardised are the signalling interfaces, for example the ATM NNI interface as defined in ITU-T recommendation Q2140 and SIP which is described by IETF RFC 3261.

6.3 Signalling Protocol The most important aspects that should be considered when selecting the control plane and signalling protocol for HAPs are: •

Its ability to enable and achieve the interoperability of networks operated by different operators and the interoperability of networks based on different underlying technologies (architecture and design goal);

•

ease of operation;

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•

scalability of the protocol (topology related issues);

•

performance and security.


SIP (Session Initiation Protocol) being defined by IETF is considered to be the signalling protocol of choice in IP networks, all-IP UMTS network concepts and next generation networks due to its strengths. Therefore, the use and application of SIP in HAPs seems to be a natural step at this stage. In what follows we provide rationale behind the above statement. In order to do that we analyze SIP based on the requirements of the IETF Next Step in Signaling (NSIS) Working Group for signaling protocols in next generation networks (the Internet-Draft Requirements for Signaling Protocols ), which requirements are grouped into the following groups: •

architecture and design goals

•

topology issues

•

messaging

•

performance and security.

It is worth mentioning from the viewpoint of the network operation that even if we choose SIP for HAPs, it is unlikely that the SIP processing will be performed on-board because of reliability reasons.

6.3.1 Architecture and Design Goals The modular architecture of SIP enables interworking with several protocols in diverse scenarios. On one hand, UDP, TCP or another transport protocol can be used to send SIP messages. On the other hand, a SIP domain can interwork with another domain using a different signaling protocol (e.g. SIPPSTN interworking). Thus, using SIP in the control plane of HAP networks facilitates network integration and interworking in a great extent. Depending on the protocols used, SIP can offer different services to the users. However, the basic functionality and operation of SIP is independent of any of these protocols. SIP provides primitives that can be used to deliver opaque objects. These primitives are typically used to provide and to develop services. There are additional properties, which make the implementation of new services easier: SIP can use IPsec or TLS for securing messages and works with IP tunneling as well. [54] SIP is fully compatible with IPv6 and SIP is capable of providing mobile environment too. [55] SIP users maintain the same IP address, despite their movement between the radio cells. In other words there is no effect on SIP, because the movement of users is transparent to SIP.

6.3.2 Topology SIP can be used in several scenarios of network entities, such as between user-user, user-network and network-network (within one domain and between domains). SIP can also be used in parts of the network, while other parts use different signaling protocols. This means that for the adaptation of SIP it is sufficient that a limited range of network devices support SIP (or a subset of SIP functionality). SIP also allows transparent signaling: if a proxy server cannot interpret a header field in a message, it simply passes it further. With name mapping and redirection services, users can maintain a single externally visible identifier regardless of their network location.

6.3.3 Messaging SIP has a flexible message structure, which allows the operator to retain the network in a stable state during the working of SIP. More precisely, SIP supports the explicit erasure of state and also supports the automatic release of state after failure. This fault tolerant nature of SIP can be extremely useful while applying HAPs in dynamically changing environments like the provision of communication for special events, disaster sites, or in mobile scenarios. 29th Jan 2004


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The SIP protocol is fairly stable and robust, and there is continuing work to improve the handling of error conditions and the behavior under heavy load. SIP uses a generic event monitoring and notification mechanism for sending notification upstream, as it is described in RFC 3265 – SIP Specific Event Notification. The flexible message structure also enables the exchange of local information (information exchange inside the domain).

6.3.4 Performance The most important requirement in the performance issue is the scalability of the signaling protocol. SIP uses the scalable DNS framework to support scalability. DNS is able to store the required number of addresses and support local caching, which allows consistent information to be distributed in the network. SIP authentication and routing can be provided by SIP proxies spread throughout the network. After a call has been set up, SIP provides direct communication between the entities over the IP network, without any centralized point of control that might become a bottleneck. SIP scales well in an individual server too, because it includes identification fields for rapid matching of messages to dialogs and transactions. Appropriate implementations can load balance across clusters of machines using DNS. SIP is a text-based protocol and originally was designed for high-bandwidth environments, however can be compressed to notably decrease the bandwidth required. SIP uses a generic compression framework, which is defined in RFC 3320 SigComp.

6.3.5 Security There are two basic security mechanism used in SIP, authentication and data encryption. SIP offers an authentication algorithm built on the HTTP Digest authentication, -as described in RFC 3261 - for the authentication of signaling requests. Applying this mechanism the SIP user agent client can identify itself to a user agent server, to an intermediate proxy server or to a registrar server. Therefore, SIP authentication can only be used in user-to-user or user-to-proxy relations. Proxy-to-proxy authentication can be performed using transport- or network-layer authentication protocols such as TLS or IPsec. The mutual authentication of proxy servers is a very important issue, because it significantly reduces the possibility of some attack techniques, such as denial-of-service or impersonating a server attacks. Because the HAP uses a multiple access scheme (see page 38) the support of authentication and IPsec by the signaling protocol is a very important requirement. SIP was designed with IPsec security in mind, which makes SIP an attractive candidate for the applied signaling protocol in HAPs.

Figure 20: Digest authentication The SIP authentication procedure is a challenge-based mechanism: when a server receives a request, it may challenge the sender of the request to prove her/his identity. The challenge contains a nonce value that is a string uniquely generated and applied for one challenge only. Both the client and the server share a secret password, and the client calculates the response value using function F with the

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secret password and the nonce value. After becoming the response value from the client in another request message, the server authenticates the client. One of the most important advantages using this mechanism is that the password is never sent in plain text. Figure 20 is an illustration of the digest authentication procedure. The function F defines how to combine the input parameters with some iterations of a digest algorithm. The default digest algorithm is MD5, but it allows the use of a different digest algorithm, which can be indicated in the challenge. Note that the destination server and an intermediate proxy server could challenge the authentication. A specific header carried in the challenge makes enable to the user to distinguish the two cases. Data encryption is used to ensure integrity and confidentiality of SIP communications, letting only the intended user decrypt the data. There are two kind of encryption in SIP: end-to-end and hop-by-hop encryption. End-to-end encryption can be used for all the data that does not need to be accessed by intermediate proxy servers, and it is performed by the S/MIME mechanism. End-to-end encryption cannot be used for the whole SIP message, as there are certain fields that need to be read by intermediate proxy servers, such as From, To, Via headers. In this case hop-by-hop encryption can be performed by security mechanism external to SIP, such as TLS or IPsec.

6.4 Third Party Applications Providers The HAP operator and a primary service provider – often termed an ASP (Application and Service Provider) - are likely to form an agreement on running a set of applications and services to end users. However, it is also important to identify steps and rules for allowing other ASPs to offer their services over the same platform. These “third party” ASPs will need to conform to service agreements defined by the primary ASP and network operator. Equally, the primary ASP and HAP operator will need to provide a set of conditions for the network to allow third party ASPs seamless connection to the network, including: •

Capacity

•

Security Requirements

•

Interfaces

•

Subcontracting

•

Audits

Historically, the standards development organisations in telecommunications, such as ITU-T and ETSI, focused on the specification of frameworks and protocols. However, organisations such as Parlay/OSA used the Application Programming Interface (API) approach in communications in order to allow IT companies to write and ASPs to operate their applications. The API approach has several advantages: •

Applications can be written by programmers not so familiar with telecommunication network and signalling details,

•

Application are portable: they will run on a variety of underlying networks and protocols without change,

•

Third party ASPs can run their own applications in an un-trusted domain using the API to communicate securely,

•

The primary ASP can buy “off-the-shelf” applications and operate them over the network’s standard API interface.

6.4.1 Parlay The features that these APIs offer, based on the definition by Parlay/OSA [2], include: •

Common Data Definitions The objects and types used throughout the Parlay specifications.

•

Common management functions: the Framework

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How applications authenticate themselves to the network. How applications discover what facilities are available from the network. Fault and load management. •

Capabilities, related management and control functions 

Mobility How applications find the location of a terminal. How applications request notifications when terminals change location.



Terminal Capabilities How applications find out the features of the terminal.



Data Session Control How applications manage data sessions initiated from terminals. This is typically used for GPRS (and other 2.5G) applications.



Presence and Availability Management How applications manage presence “I am at my computer” / “I am away” and availability “I am in a meeting” / “I am available to be contacted”. Typically used in Instant Messaging types of applications and their extension to wireless networks.



Account Management How applications query accounts and charge history.



Charging How applications request payment for services (“content-based charging”). How applications reserve payment for a future service. This allows applications to work in a pre-paid network.



Call Control How applications set up calls in the network How applications set up multiparty (conference) calls in the network How applications are used to route calls from the network, e.g. so that an enterprise application can manage call diversions for an employee. How applications can set up multi-media calls.



Generic Messaging How applications interact with messaging systems, such as voice, FAX or email.

6.4.1.1 Requirements to adopt Parlay/OSA To promote these network capabilities to third party ASPs, the Network Operator must install a Parlay Gateway in its system. This gateway provides the implementation of the functions in the Parlay API. The gateway is not a monolithic server, but it is a highly modular distributed component system composed of a unique entry point for ASPs (the Framework) and several SCSs (Service Capability Servers). An SCS implements one or more of the capabilities (SCF) recited in the previous section and hides network structure, protocol and implementation details from the application designer. In contrary, the Framework is responsible for those features of the gateway that are independent of the underlying telecommunication network. Our main interest here is the Framework’s support of service discovery and its security related functions; these will be studied further in the next section. The Parlay API is defined in several programming environment, the basic idea being “One API for each developer community”. Each one of these APIs builds on a distribution middleware, namely CORBA, Web services or Java RMI. To support these distributed environments the interface between the external ASP and the Network Operator must support IP as its communication protocol. Figure 21 shows the architecture of the Parlay gateway and its connections to the network and ASPs.

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Primary ASP in trusted domain

Applications

Other ASPs in un-trusted domain

Application Application

IP network

Distributed Software Bus (e.g CORBA)

connecting ASPs and Telco API calls

Telco Parlay Gateway (distributed)

Call Control

Framework

User Interact.

Charging

Mobility

16 APIs

Mapping to signaling and logic implemented by SCS manufacturer

SIP, MGCP

Signaling

SS7, TCAP, INAP

ANSI-41, MAP, CAP

SCP

HLR

Networks

VOIP/3G

PSTN

2G (GSM)

Figure 21: Interaction of applications and networks using Parlay To adopt Parlay in a HAP network, the following tasks should be accomplished: •

Locate the physical entities for installing the Parlay gateway ( the Framework and SCSs)

•

Assure IP connection and middleware functionality between the gateway and 3 party ASPs,

•

Select those SCFs that could be supported by the network,

•

Modify SCS functionality to fit physical implementation and signaling used in the network.

rd

6.4.1.2 Service discovery While Parlay defines several SCFs, it is not required that an operator’s gateway supports all of these. Instead, the ASP can query the Framework about available capabilities and their respective parameters (e.g. the maximum number of parties handled in a conference call). Then, if required by the ASP, the Framework can grant access to an SCS implementing the functions defined in the SCF. The query mechanism has its respective pair on the server side: the operator can dynamically change the structure, capabilities and performance of the gateway by adding new SCSs to the gateway and registering these in the Framework. Interfaces in Parlay use a logic model of network entities; this model is independent of the physical implementation and the signaling used in the network. It is the role of the SCS to handle the control plane of the network by mapping API calls to the appropriate signaling messages. Thus, depending on the capabilities of the network and the signaling protocol supported by the network, different functionalities can became accessible to external ASPs through the Parlay gateway. 6.4.1.3 Security in Parlay/OSA One of the most prominent achievements of Parlay is the provision of secure access to capabilities of the telecommunication network for third party ASPs. To achieve this goal several security related objectives must be addressed: 29th Jan 2004


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•

Confidentiality and data integrity

•

Accountability

•

Protection from illegitimate use

•

Availability and system integrity


Parlay addresses all of these problems by using well-established and proven security mechanisms. These include: •

Authentication using challenge/response exchanges

•

Transport, and session level security mechanisms and secure contexts included in the distribution middleware

For a detailed analysis of security issues in Parlay please see [56]. 6.4.1.4 Available standards The set of APIs which are generally referred to as Parlay/OSA or simply Parlay are defined in the specifications of several standardization bodies, namely •

ETSI

•

The Parlay Group

•

3GPP

•

ITU-T

•

JAIN group

In 2001 a body called Joint API Group [57] was set up to harmonise standardisation efforts. Today ETSI TC SPAN, the Parlay Group, 3GPP CN5 and several member companies of the JAIN consortium form this group. The API is first defined in UML and than, using the latest document and code generation techniques, the detailed technical description documents, the IDL code, WSDL code and Java API are all produced from a single source UML model. This ensures alignment between all versions, all formats of the API. ETSI publishes the master specification of the APIs under ES 20x 915. The Parlay Group point to this published ETSI specification instead of re-publishing it. 3GPP maintain their own specification, TS 29.198, which has the same structure as the ETSI specification. Each part of TS 29.198 is a subset or a copy of the ETSI specification. ITU-T will also adopt the specifications of the Joint API Group. The JAIN group focuses on providing Java reference implementations of the Java API.

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7. Commercial and Technical Feasibility of Applications and Services for HAPs 7.1 Types of Information, Services and Applications Suitable for HAPs Interactive conversational Type of information Moving pictures and sound Broadband services Video telephony, ISDN videoconference, Video surveillance, Video/audio information transmission service (DVB) Applications E-learning, E-advertising, Mobile video surveillance, TV broadcasting Type of information Broadband services Applications

Data High-rate unrestricted information Tx. service, FTP Wireless LAN´s interconnection, Data file transfer

Type of information Broadband services

Multimedia High resolution image communication service, Mixed document communications service Desktop multimedia Mobile emergency services, Mobile tele working

Applications

Interactive messaging Type of information Mixed documents Broadband services Multimedia mail Applications Electronic mailbox service for multimedia

Interactive retrieval Type of information Broadband services Applications

Tex, data, graphics, sound, still images, moving pictures Data retrieval service, Multimedia retrieval service E-commerce, Multimedia library, Tourist information,etc

Distributed Broadcast Type of information Video, Audio Broadband services MPEG-2 or 4 Applications TV programs distribution, DAB

7.2 Parameters for Services and Applications Applications can be divided in three groups related to the bit rate of the information source. •

Group A : 256,384 Kb/s

•

Group B : 385, 2000 Kb/s

•

Group C : > 2 Mb/s

In each group, the traffic characteristics of bit rate and latency delay, and the communications characteristics of “burstiness” (peak bit rate to average bit rate) and BER can be categorised as in the following tables.

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Group A (256,384) Kb/s Application Bit Rate (Kb/s)

ISDN videoconference Data File transfer (FTP) Web browsing e- commerce

384

200

Burstiness (peak bit rate to average bit rate) 1-5

384

1000

1-50

10

384 384

non real time 500

1-20 1-20

10 -6 10

Latency 5min

Burstiness 1-20

BER -6/-4 10 -6 10

200 ms

1-5

10

500

1-20

10

200

1-5

10

500

1-5

10

Bit Rate 2400 2800

Latency 500 200

Burstiness 1-20 1-20

BER -6 10 -6 10

8000

500

1

10

1 Mb/s 1 Mb/s 10 Mb/s 10 Mb/s 11 Mb/s 54 Mb/s

No data No data No data QoS, for voice/video

-

10 -6 10 -6 10 -6 10 -6 10 -6/-8 10

Group B (385, 2000) Kb/s Application Bit Rate Monitoring 500 Emailbox for 1500 multimedia HD 2000 videotelephony Mobile 2000 teleworking Mobile video 2000 surveillance E-newspaper 2000

Group C (> 2 Mb/s) Application Multimedia library Mobile emergency services TV programs (MPEG2-4) HomeRF Bluetooth RadioLAN HomeRF2 802.11b (Wi-Fi) HiperLAN2 802.11a 802.11g 802.11e

54 Mb/s 54 Mb/s 54 Mb/s

802.16 (WiMAX) HiperMAN

70 Mb/s

Latency (ms)

BER -6

10

-6

-6

-6

-6

-6

-6

-6

-6

Adds QoS not present in a,b,or g QoS No data

7.3 QoS The term service in the telecommunications context seems to be obvious: pertains to the capability to exchange information through a telecommunications medium, provided to a customer by a “service provider”. The ITU and ETSI approaches to QoS-related terminology are almost the same. In fact, both organisations adopted the concepts of each other while developing the notion of QoS. They use the same basic definition of QoS expressed as “the collective effect of service performance which determine the degree of satisfaction of a user of the service.”

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The term quality, which can be defined as “the totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs,” is less tangible. In fact, the meaning of this term is very broad. In telecommunications the term quality is commonly used in assessing whether the service satisfies the user’s expectations. Features and parameters of the service are well-specified [36,37,38,39,40]. The evaluation, however, depends on various criteria related to the party rating the service. Customers assess it on the basis of a personal impression and in comparison to their expectations, while an engineer expresses quality in terms of technical parameters. This discrepancy may sometimes lead to misunderstandings. For example, a service in an IP environment (IP-based service) is defined by ITU as “a service provided by the service plane to an end user (e.g., a host [end system] or a network element) and which utilises the IP transfer capabilities and associated control and management functions for delivery of the user information specified by the service level agreements”. In this case, ITU describes parameters, attributes and classes of IP-based services.

7.3.1 QoS Parameters In packet networks, QoS is expressed by at least the following set of parameters that are also meaningful for most IP-based services: •

Bit rate of transferring user data available for the service, or target throughput that may be achieved.

•

Delay experienced by packets while passing through the network. Delay may be considered either in an end-to-end relation or with regard to a particular network element.

•

Jitter – variations in the IP packet transfer delay. Again, jitter can be applied to an end-to-end relationship or a single network element.

•

Packet loss rate, usually defined as the ratio of the number of undelivered packets to sent packets.

These parameters describe the treatment experienced by packets while passing through the network. They can be translated into particular parameters of the network architecture components used to ensure QoS. They are finally mapped into the configuration of network elements. They are also closely connected with protocols used in the network and equipment abilities.

7.3.2 Traffic classes and QoS Table 6: Traffic Classes and QoS Parameters Traffic parameters

Conversational Class X X X

Streaming Class X X X

Interactive Class X

Maximum bit rate Guaranteed bit rate Maximum service data unit (SDU) size SDU format information X X SDU error ratio X X X Residual bit error rate X X X Delivery of erroneous X X X SDUs Delivery order (yes/no) X X X Transfer delay X X Traffic handling priority X Admission/retention priority X X X Information from [41] – see also this section on Traffic Classes in this document.

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Background Class X

X X X X

X

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7.4 Analysis and Derivation of Favoured Services and Applications In this sub-section we analyse the business case for services and applications described in this report with the objective of predicting those that will yield the best commercial opportunity for HAPs. Additionally, we consider which services should be demonstrated during the two CAPANINA trials. In addition to the millimetric band broadband applications and services considered in this report, HAPs are also likely to be used for services outside the CAPANINA remit, for example video surveillance, UMTS base station provision and military applications. These services are not analysed here, but may be a part of future HAP, perhaps together with a broadband payload.

7.4.1 Competitive Technologies to HAPs – attributes and costs The business case for accessing the services identified in this report via competitive technologies to HAPs, e.g. fibre, cable, wireless, satellite and DSL, must be considered. From this, we can identify the best opportunities for HAPs, e.g. where HAPs should be positioned in the marketplace. Terrestrial fibre/cable broadband services are not (yet) universally widely available and satellite/wireless opportunities for point to point broadband services are currently limited by cost. HAPs may offer an opportunity to expand broadband services into the community at a realistic cost, especially to give access to those citizens that live in small rural communities. European or national government subsidies may become available to support the aim of providing broadband for all. For example the e-Europe action plan, approved by the Seville European Council in June 2002, aims to provide broadband connections to all public authorities, universities, schools and medical centres by 2005, and to support the widespread availability of Internet access to all citizens, regardless of their location. HAPs may have a part to play. DSL (ADSL and SDSL), making use of existing twisted pairs originally installed for telephony, is the primary current route to broadband for most Telcos. DSL data rates are dependent on the user’s distance from the DSLAM (normally located at the local telephone exchange). As an approximate guide (UK experience), 512 kbit/s downstream can be made available to users up to 6 km from the DSLAM, but a 2 Mbit/s service tends to require the user to be much closer. These figures are very dependent on the quality of the twisted pair network. A small percentage of users may be connected to an ADSL enabled exchange, yet be outside the distance limit for reliable broadband operation. It can be therefore argued that the practical data limit imposed on most ADSL lines does not yet allow for truly broadband services such as VoD, although it should be noted that the higher data rate ADSL offerings (e.g. 2 Mbit/s) could provide VoD. However, modern video codecs could see VoD at data rates as low as 1 Mbit/s. France Telecom, for example, is considering TV services over ADSL [http://www.rd.francetelecom.com/en/technologies/ddm200311/techfiche4.php]. SDSL (Symmetrical DSL) offers broadband data rates in both directions and is mainly aimed at business customers Cable networks are commonplace in areas of high-density population in Europe, but are less common in suburban or rural locations. Cable networks were originally designed for TV distribution (cable TV) with one-way traffic to the users. Over the years cable networks have been re-engineered to carry two-way services and now offer bundled services such as entertainment TV, broadband Internet and voice services. However, many networks have limited upstream data rates, so it is sometimes difficult for cable modems to support business customers who tend to require higher upstream data rates. There is poor cable network penetration outside high-density population centres within Europe because cable installation is expensive and expansion to rural areas is not always supported by the business case for revenue generation. Fibre networks are the future, and their extensive bandwidth allows service providers to deliver almost any service, including high definition TV. Fibre is expensive to install, but it can be justified in science and technology parks, multi-tenant office and residential blocks, high-density population centres, etc. Ethernet access services are currently available over fibre in some parts of Italy and Sweden, and in small areas of the UK and Germany. In the UK, for example, it is possible to connect customers to Ethernet backbone networks using a LAN extension service in the BT MAN. This makes it possible to offer national Ethernet WANs. 29th Jan 2004


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Satellite can offer a broadband solution to users, and there are a number of one way (satellite RO with terrestrial return) and two-way products on the market. However, European Ku-band satellites (e.g. SES Astra, Hotbird) with wide beams are better suited to broadcast applications, such as satellite TV, or multicast services. Satellite is less efficient for point to point broadband services such as VoD (data intended for one recipient can be broadcast over all of Europe – a waste of capacity). Future Kaband multiple spot beam satellites, such as the Hughes Spaceway [6], will be better suited to point to point broadband communications, and will be a direct competitor to HAPs. BFWA (Broadband Fixed Wireless Access) point to multipoint and mesh radio networks are used to provide broadband connectivity in some rural areas. Terrestrial DVB transmissions could include a data component within the multiplex to offer downstream broadband to cheap receivers, with a terrestrial PSTN return, in much the same way as described for RO satellite. W-LAN can be used to provide broadband connectivity at hot spots such as airports, stations, rest areas, etc. 7.4.1.1 Broadband Penetration Broadband penetration though DSL and cable networks has enjoyed significant growth in the last few years, as illustrated by Table 7, Table 8, Table 9 and Table 10. Table 11 indicates the forecast growth. Of perhaps more significance is the availability of broadband services to potential users, as opposed to broadband penetration (take-up by customers of the offered services). For example, in the UK, ADSL is available to approximately 85% of households now and is confidently expected to reach 90% availability within the next two years. The target is to get broadband to all communities. However, the UK example shows that even where ADSL availability exists at a wholesale cost less that €20 per month, broadband penetration (customer take-up) of ADSL is currently only around 6%. However, SME take up of broadband is much higher, at 33% and growing fast [58]. To increase this take up rate, especially to the huge consumer market, we must provide applications and services that the consumer wants at prices that he/she considers reasonable. Although the UK has a target to achieve 100% broadband availability, currently, rural communities are disadvantaged [58]. Broadband is available to: •

99% of the population in urban areas

•

84% of the population in suburban areas

•

51% of the population in market towns

•

16% of the population in rural villages

•

4% of the population in remote rural areas

This digital divide is much worse in less developed countries, and suggests a place for alternative technology such as HAPs.

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Table 7: Broadband Penetration at 2002

For background to Table 7, see [13], for Table 8 see [15]

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Table 8: DSL lines, cable modems and total broadband lines penetration in 2003

Country

Europe, Asia

Thousands of lines

Growth in Q3 2003

at 30 Sep 2003

(relative to Q2 2003)

DSL

Cable

Total

DSL

Cable

Total

15529.9

5204.9

20734.8

14.8 %

10.3 %

13.6 %

UK

1414.7

1231.3

2646.3

32.0 %

12.6 %

22.2 %

Germany

4250.5

71.0

4321.5

10.0 %

9.9 %

10.0 %

France

2429.5

348.2

2777.7

19.2 %

4.0 %

17.0 %

Italy

1672.0

175.2

1847.2

16.5 %

17.6 %

16.6 %

Spain

1433.4

404.5

1837.9

10.1 %

32.6 %

14.4 %

Israel

358.0

52.0

410.0

10.2 %

23.8 %

11.7 %

Hungary

80.1

35.6

115.7

24.3 %

3.8 %

17.2 %

Sweden

508.0

341.7

849.7

4.9 %

9.9 %

6.8 %

Table 9 : Percentage increase in broadband in Q3 2003

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Table 10 : Broadband lines per 100 of the population

Table 11 : Broadband Subscriber Forecasts

From reference [14]

7.4.2 Cost Comparisons Table 12 provides a snapshot cost comparison of broadband services in the UK (valid 12 January 04). The comparison covers, ADSL, cable, satellite, W-LAN and GPRS networks offering asymmetric data rates up to 2 Mbit/s downstream. It should be noted that these are retail prices, including the ISP value-add and mark-up. As an example of wholesale prices, BT currently market ADSL to wholesale customers at £13 (€18.57 assuming €1=£0.7) per month, less with volume discount [5]. This gives some indication of the cost levels that HAPs must achieve to be competitive where alternative routes to broadband exist. In this case, HAPs must offer something more, e.g. greater bandwidth supporting a new generation of applications and services.

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Table 12: Cost comparison of broadband networks in the UK ISP BT Broadband (ADSL)

Offer 512 K (256K up)

AOL Broadband (ADSL)

512K (256K up)

NTL Broadband (Cable)

150K (64K up)

Cost (12/1/2004) Set up cost: £30 connection £50 modem (£40 if you buy online) Monthly cost: £27 when paying by Direct Debit (or Monthly Payment Plan) £28 otherwise Free Set up cost Monthly cost: £27.99 (12 months contract) £ 17.99 free installation + 1 month free

600K (128K up)

£ 24.99 free installation + 1 months free

1M (256K up)

£ 34.99 free installation + 1 months free

O2 (GPRS)

GPRS rates

Vodafone (GPRS)

GPRS rates

Europe Online E-DSL Service

768 K (PSTN up)

(One-way satellite PSTN return)

(Promotional offer, standard installation fee £75) Monthly fee: £42.55 Inclusive data: 125 MB Additional data: £0.85 per MB Monthly fee: £52.88 Inclusive data: 150 MB Additional data: £1.18 per MB 1 year subscription at 9.9 Euro per month or 99 Euro per year include: 500 MB of EOL FastSurf per month 1 GB of downloads with File Fetch 1 free film every month, etc. www.europeonline.com

Rapid RapidSat Satellite Broadband

Up to 2 M (PSTN up)

Installation and equipment charge: £199 Monthly fee: £16 (top include 300MB with guaranteed QoS, and unlimited content downloads) www.rapidsat.com/rapidSatFlash/main.htm

(One-way satellite PSTN return) BT Openworld Business Satellite (Two-way satellite)

500 K (150K up)

Business Satellite 500/1 Equipment + installation (one-off set up fee) £649.00 + £300 = £949 Monthly fee: £59.99 Business Satellite 500/4 Equipment + installation (one-off set up fee) £1,049.00 + £300 = £1,349 Monthly fee: £109.99 (Contract rental or purchase plan also available) www.btopenworld/satellite1

Aramiska (Two-way 29th Jan 2004

Installation fee: £500 Monthly fee: FP6-IST-2003-506745-CAPANINA

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satellite)

512K (128K up) 1024K (256K up) 2048K (512K up)

£199 £249 £349 www.aramiska.co.uk

BT Openzone (WiFi)

Not marketed

Prepaid: £6 for 1 hour worth of usage (within 24 hours from the first log-on) £15 for unlimited usage within 24 hours

UK Explorer (WiFi)

T-Mobile HotSpot (Wi-Fi)

BT Openzone uses the 2.4 GHz radio frequency to send and receive data at current speeds of up to 11 Mbit/s over distances up to 100 metres. BT Openzone devices communicate with 'wireless LAN base stations' that are in turn connected to the Internet. Not Marketed

Not Marketed

Subscription: £10 per month for each user for 120 minutes monthly allowance (ex. VAT); additional time 20p per minute £20 per month for each user for 300 minutes monthly allowance (ex. VAT); additional time 15p per minute £40 per month for each user for 900 minutes monthly allowance (ex. VAT); additional time 10p per minute £85 per month Unlimited (ex. VAT)

Depends on location. Prepaid example is £4 for 30 minutes (at Birmingham airport). Monthly subscription also available www.ukexplorer.com Pay-as-you-go: $6 for 60 minutes ($0.1 per additional minute) Pre-paid: $9 for 24 continuous hours Monthly Subscription: $39.99 per month Annual Subscription: $29.99 per month (12 months commitment) www.t-mobile.com/hotspot/

7.5 Candidate Services for HAPs A strong selling point of HAPs is that they can give the governments of developing countries direct control and management of their communications networks. HAPs can provide, at a stroke, a modern digital broadband communications network, at a competitive price, to areas of poor terrestrial infrastructure. A satellite may be financially out of reach to a developing country government, but a HAP is a possibility. HAPs, with their superior link budget, small cellular structure and frequency re-use, is better positioned than satellite for cost competitive point to point links, and may also be suited to local or regional broadcasts such as regional TV distribution. Only radio can support mobile applications and HAPs have a part to play here with the potential to provide broadband communications to vehicles and trains. Regional TV broadcasting and broadband Internet can be extended to new regions assisting economic development. In addition to the broadband payload, UMTS mobile communications, military and surveillance payloads (outside the CAPANINA remit) can also be carried. The package as a whole could therefore be of interest to developing countries. In spite of these advantages, the business case for broadband services and applications via HAPs is not clear-cut in the developed world (i.e. including Europe). For example, ADSL broadband currently reaches 85% of UK homes at; it will soon reach 90% of the country. However, even at wholesale prices of less that €20 per month, customer take-up is only about 6% [5]. The situation is similar in 29th Jan 2004


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other European states. If HAPs is positioned in head-to-head competition with ADSL, it must better these prices (difficult) or offer alternative services and applications (e.g. higher data rates than are possible with ADSL, and/or broadcast/multicast services). The advent of VDSL may further reduce the opportunities for HAPs in the developed regions. HAPs broadband services are therefore probably best targeted at rural areas, not yet ADSL (or cable modem) enabled. This might be less than 5% of the population within the established EEC, but significantly more in some of the new entrant states. In this respect, the competitive technologies are satellite (VSAT) and BFWA. Broadband Internet and Intranet are probably the main drivers for HAPs within the broadband payload. This requires that access to an ISP (or ISPs) is provided for HAP users. Broadband Internet gives access to a myriad of services through the Internet, together with opportunities for access to company Intranets, teleworking, etc. Broadband Intranet will also improve business prospects in developing countries by connecting remote offices with the corporate network. Other IP based entertainment services can also be considered e.g. video streaming and especially VoD. These services could be viewed in real time, e.g. a live “local” football match, or they might be delivered to a user storage medium for user access at a later time. Value-add services broadcast services, such as TV and radio should also be considered, although wide area TV distribution might be more efficiently provided by satellite. Local or community TV distribution could be an option, but HAPs would have to demonstrate superiority over the (normal) terrestrial distribution method (perhaps for TV distribution to small island groups).

7.5.1 Applications for CAPANINA Trials At the time of writing two trials are proposed within the CAPANINA project. These are : •

A tethered aerostat

•

A stratospheric balloon

Later in the project, it is possible a third trial may be conducted in partnership with CRL, but details are still in the planning stage so no further guidance on practical applications for these tests can be given at this stage. Appropriate applications will need to be selected for each of these trials. Although the implementation and interfacing of these applications is outside the scope of Deliverable D01, it is important to provide an early indication of the most likely applications for each. In this respect, it is important to consider the objectives of each trial and the benefits to be achieved, weighed against the likely complexity of implementation. At this early stage of the project, these suggested applications must be considered as guidelines, and subject to change as the trial plans develop in other workpackages. 7.5.1.1 Trial 1 : Tethered Aerostat A tethered aerostat will be positioned at a height of about 300 metres above a Hub ground station. The Hub will connect with the aerostat via a fibre cable, and a Ka-band (circa 28 GHz) radio link will connect to two or more user terminals located in a single beam, probably of about 5 km diameter. A commercial [TDM/TDMA ?] system based on Broadband Fixed Wireless Access (BFWA) technology will facilitate services and applications. IP datagrams will be encapsulated within ATM cells in both directions. Delivery from the Hub to the user terminals is likely to be IP data via TDM. Data from user terminals to the Hub is likely to be a multiple access protocol, e.g. MF-TDMA, Slotted Aloha, etc. Total (shared) data rates in each direction are likely to be about 32 Mbit/s. Broadband Internet / Intranet is a strong candidate application for this trial. It will meet most of the objectives and will provide a feature-rich broadband demonstration platform. This will provide access to a vast range of Internet applications and the ability to download files and test speeds. It would also add impact if a secure connection into a company Intranet could be demonstrated, for example a IPSec connection over a VPN. 29th Jan 2004


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The proposed user interface at the remote sites is Ethernet 100 base T. Connection to a PC for broadband Internet applications is therefore straightforward. The proposed interface to the Hub earth station is E3. This will require connection to an Internet Service Provider (ISP) Point of Presence (PoP). BT can provide access to the Internet from the Adastral Park site in the UK if required. Video streaming to the remote terminals would also provide a very good demonstration of broadband content, and would have high impact. Streamed, high quality, video content can be provided from Adastral Park via IP multicast servers. Alternatively, if an E3 link is not available, it may be possible to co-locate video streaming servers with the Hub equipment. VoD requests and transmissions would also be a useful demonstration of a likely service, if this is possible at a realistic cost. File Transfers can be undertaken between user terminals without the necessity of connecting the Hub to an ISP PoP. This would test the capability of the HAP, independently of the terrestrial backhaul. However, value would be obtained by using one of the speed test options on the Internet to demonstrate broadband Internet file delivery speeds, which would of course require connection to an ISP PoP. Tests to a mobile: a stated objective of CAPANINA is to construct an outline system design of broadband service delivery from HAPs to high-speed vehicle users. If possible, it would be beneficial to extend the broadband Intranet / streaming applications to a vehicle on the move. 7.5.1.2 Trial 2 : Stratospheric Balloon The second CAPANINA trial will use a stratospheric balloon to bring the TLC payload to the altitude foreseen for the studied applications. The meaning of trial 2 is to validate some of the aspects evidenced during system definition and during trial 1 - foreseen to be critical once displaced at high altitude. Specifically the feasibility of file transfers and/or video streaming could be tested in order to validate the propagation channel, ground coverage area, aerial support stability and other issues for TLC devices into stratospheric environment. Relatively simple and targeted trials and measurements will take advantage of the 6-8 hours flight mission of the aerial support, and it may not be possible to provide an interface to the terrestrial core, e.g. to connect the Hub equipment to an ISP PoP.

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8. Conclusions HAPs may offer an opportunity to provide broadband services to local or regional coverage areas in advance of, and/or at a competitive price to, alternative technologies. CAPANINA is specifically concerned with broadband services at millimetric wavelengths, with trials planned to demonstrate service concepts. This report lists a range of possible services and applications for HAPs and then identifies candidate services for HAPs and for the CAPANINA trials. HAPs are also likely to be used for services outside the CAPANINA remit, for example video surveillance, UMTS base station provision and military applications. These services are not covered within the main body of this report, although some information is provided within the appendices. Consideration is also given to the positioning of competitive technologies to HAPs, e.g. ADSL, fibre/cable, BFWA, satellite, UMTS 3G, etc., and the impact on the HAP business case. Currently, in developed countries, the strongest competition to a HAP broadband service is from ADSL and cable networks. Satellite and BFWA are also players. The future is likely to see VDASL and an extension of fibre, eventually to the home. Ka-band spot beam satellites will offer efficient broadband services in the USA this year, and future satellites may offer similar services to Europe and other parts of the world. The competition for HAPs will be strong. The strongest business case for broadband HAPs is probably in developing countries. HAPs can give the governments of developing countries direct control over their communications networks. HAPs can provide, at a stroke, a modern digital broadband communications network at a competitive price. Regional TV broadcasting and broadband Internet can be extended to new regions assisting economic development. UMTS mobile communications, military and surveillance payloads (outside the CAPANINA remit) can also be carried and are also of interest to developing countries. The use of HAPs on a temporary basis at disaster sites and for special events is also a possibility. HAPs, unlike terrestrial infrastructure, can provide uniform coverage of a given zone, within which all potential users are offered equal access and quality of service. HAPs, with its superior link budget, small cellular structure and frequency re-use, is better positioned than satellite for cost competitive point to point links, and may also be suited to local or regional broadcasts such as regional TV distribution. Only radio can support mobile applications and HAPs have a part to play here with the potential to provide broadband communications to vehicles and trains. Rain fading, especially with HAPs employing V-band, could cause serious degradations to some services. Real time services, such as TV and video streaming, would be most affected. Fading countermeasures techniques may offer some QoS improvements.

8.1 Candidate Services for HAPs Broadband Internet and Intranet are the main broadband drivers for HAPs within the broadband payload. Broadband Intranet would also improve business prospects in developing countries by providing efficient communications to SMEs, connecting remote offices into a corporate network and facilitating teleworking. Other IP based entertainment services can also be considered e.g. video streaming and especially VoD. These services could be viewed in real time, e.g. a live “local” football match, or they might be delivered to a user storage medium for user access at a later time. Value-add services broadcast services, such as TV and radio should also be considered, although wide area TV distribution might be more efficiently provided by satellite. Local or community TV could be an option.

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8.2 Candidate Services for the CAPANINA Trial The first CAPANINA trial will use a tethered aerostat located within the UK. Broadband Internet is suggested as a primary demonstration. This will provide access to a vast range of Internet applications and the ability to download files and test speeds. A second application should have visual impact. It is suggested that a video server is connected to provide high quality content directly to the HAP up-link, thereby demonstrating the ability of the HAP to provide video services to users. The server could also be used to test file upload and download speeds of the HAP divorced from the Internet. A demonstration of user to user file exchange, independent of the terrestrial core, should also be tested. VoD requests and transmissions would also be a useful demonstration of a likely service, if this is possible, as would provision of Internet service to a mobile (vehicle). The second CAPANINA trial will use a stratospheric balloon to bring the TLC payload to the altitude foreseen for the studied applications. Relatively simple and targeted trials and measurements, e.g. file transfers and video streaming, will take advantage of the 6-8 hours flight mission of the aerial support, and it may not be possible to provide an interface to the terrestrial core, e.g. to connect the Hub equipment to an ISP PoP

8.3 Recommended Further Work •

Revision of D01 in the light of experience with the two CAPANINA HAPs trials.

•

Survey of standards work on safety and interference issues, and the relevance to HAPs. Make recommendations for further work on HAPs with standards bodies.

•

Applicability of the DVB multiplex to HAPs.

•

Analysis of new and proposed video codecs, and their impact on the data rate reduction achievable for applications such as video conferencing and VoD. What is the impact on the business case for HAPs and for competitive technologies to HAPs such as DSL?

•

Applicability of work in IETF on IP-DVB encapsulation.

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Symbols and Abbreviations ADSL API ASP ATM AWACS B3 BFWA BE BRAN BSM CMIP C/N CPE CR DHCP DNS DSL DTV DVB DVB-S E1 E2 E3 ETSI EU FEC FWA GPRS GSM HAP IETF IF IMT-2000 IDU IP ISDN ISP ITU LAN MAN MBS MF-TDMA MPEG MPLS NGN ODU OBP OSGI OSI

Asymmetric Digital Subscriber Line Application Programming Interface Application and Service Provider Asynchronous Transfer Mode Airborne Warning And Control System Broadcast Based Broadband Broadband Fixed Wireless Access Best Effort Broadband Radio Access Networks Broadband Satellite Multimedia Common Management Information Protocol Carrier to Noise Ratio Customer Premise Equipment Constant Rate Dynamic Host Configuration Protocol Domain Name System/Server Digital Subscriber Line Digital Television Digital Video Broadcast DVB for satellite A line giving data rates of 2.048 Mbit/s A line giving data rates of 8.192 Mbit/s A line giving data rates of 34.368 Mbit/s European Telecommunications Standards Institute European Union Forward Error Correction Fixed Wireless Access General Packet Radio System Global System for Mobile Communications High Altitude Platform Internet Engineering Task Force Intermediate Frequency International Mobile Telecommunications – 2000 Indoor Unit Internet Protocol Integrated Services Digital Network Internet Service Provider International Telecommunications Union Local Area Network Metropolitan Area Network Mobile Broadband System Multi-Frequency TDMA Motion Pictures Expert Group Multi-Protocol Label Switching Next Generation Networks Outdoor Unit On Board Processing Open Service Gateway Initiative Open System Interconnection

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OSS PoP PSTN QoS RF SCART STM-1 SDSL SIP SME SNMP SLA SOHO T1 T2 T3 TCP TDM TDMA TMF TMN UDP UMTS VDSL VoD VoIP VPN VR VSAT WAN WG W-LAN WRC


Operational Support System Point of Presence Public Switched Telephone Network Quality of Service Radio Frequency TV connector (Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs) Synchronous Transport Module Level 1 (155 Mbit/s) Symmetrical Digital Subscriber Line Session Initiation Protocol Small / Medium Enterprise Simple Network Management Protocol Service Level Agreement Small Office / Home Office A line giving data rates of 1.544 Mbit/s A line giving data rates of 6.176 Mbit/s A line giving data rates of 44.736 Mbit/s Transmission Control Protocol Time Division Multiplex Time Division Multiple Access Tamed Frequency Modulation Telecommunications Managed Networks User Datagram Protocol Universal Mobile Telecommunications System Very-high-data-rate Digital Subscriber Line Video on Demand Voice over IP Virtual Private Network Variable Rate Very Small Aperture Terminal Wide Area Network Working Group Wireless LAN World Radio-communications Conference

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2.

Parlay/OSA - a New Way to Create Wireless Services, 1/7/2003, Zygmunt Lozinski, Senior Technical Staff Member, IBM and President, The Parlay Group (available from www.parlay.org )

3.

Satellite Earth Stations and Systems (SES); Broadband Satellite Multimedia; Services and Architectures; ETSI TR 101 984 V1.1.1 (2002-11)

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ADSL Guide http://www.adslguide.org.uk (ADSL offerings in the UK – speeds and prices – ISP comparisons.

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ETSI TS 123 107 Technical Specification UMTS

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World Broadband Statistics Q3 2003, 2/1/2004, Point Topic Ltd 2004, Market research document available from www.point-topic.com

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Asoka Dissanayake, 2002, Ka-Band Propagation Modeling for Fixed Satellite Applications, COMSAT Laboratories Clarksburg, Maryland, paper available from http://satjournal.tcom.ohiou.edu/issue02/pdf/paper_asoka2.pdf

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Radio Communication Study Groups, 12/9/2000, Methodology for impact evaluation and operational procedure of the fixed service using high altitude platform stations (haps) for frequency sharing with other co-primary services across the international border in the band 27.5-28.35 GHz and 31.0-31.3 GHz, ITU document

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Time series of attenuation on EHF and SHF fixed satellite links derived from meterological and forecast data, RJ Watson, A Page & PA Watson, University of Bath, proc. Personal Broadband Satellite Seminar, 22/1/02, IEE, London

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Martin Chapman and Stefano Montesi. Overall Concepts and Principles of TINA, th Document TB_MDC.018_1.0_94. 17 February 1995. Also see http://www.eurescom.de/~public-seminars/1997/DOT/slides/Session2/09Gavras/ Link th checked 9 January 2004.

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(UPC-2) OECD Broadband Access for Business .Report at http://www.olis.oecd.org/olis/2002doc.nsf/LinkTo/dsti-iccp-tisp(2002)3-final

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(UPC-3) X. Patrick , “Should broadband be part of universal service obligations?” Information [2003] Volume 5, No. 1, 2003 at http://www.emeraldinsight.com

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M.Progler, C. Evci, and M. Umehira, “Air Interface Access Schemes for Broadband Mobile Systems”, IEEE Commun. Magaz., vol. 37, no. 9, pp. 106-15. Sept., 1999

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Delivering the Broadband Home, New fixed and mobile services and devices forecast 2003-2008, Margaret Hopkins, 2003, Analysis Research

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Applications and Services for Broadband HAP Delivery rd

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HeliNet – The European Solar-Powered HAP Project – TC Tozer & D Grace, CRG Department of Electronics, University of York, UK

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The HeliNet On-Board Optical Payload – Enrico Magli & Gabriella Olmo (Dipartmento di Elettronica Politecnico di Torino), Jean-Philippe Thiran (Signal Processing Laboratory EPFL), Nikolaus Schibli (Fastcom Technology).

51.

High Altitude Platforms for UMTS, B Zapfe, Bath University UK, Nov 1999

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LMDS from High Altitude Aeronautical Platforms – D Grace, NE Daly, T Tozer, AG Burr, CRG, Department of Electronics, University of York UK

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SIP Security Issues: The SIP Authentication Procedure and its Processing Load, Stefano Salsano, DIE — Università di Roma “Tor Vergata”, Luca Veltri, and Donald Papalilo, CoRiTeL — Research Consortium in Telecommunications

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SIP Market Overview, Jonathan Cumming, DCL, September 2003

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rd

End of Main Document

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APPENDIX 1 : SURVEILLANCE PAYLOAD Video/radar/infer-red surveillance is not a “broadband for all application” within the remit of CAPANINA. However, the business case for HAPs may be advanced if a surveillance payload is added to that of broadband. Therefore, brief information on surveillance applications and services is provided in this appendix.

Video Surveillance There are numerous video surveillance applications and services that might be suited to HAPs. However, HAPs suffer from several disadvantages in this respect •

Cloud cover presents a serious problem, especially in Northern Europe in winter.

•

HAPs operate at high altitudes, so the camera technology must be first class in order to achieve useful data (zoom and picture quality). In this respect, HAPs have and advantage over satellite.

•

The look-angle of HAPs is fixed, so a moving target will disappear from view when shielded by buildings, etc

Most applications will require a camera (or cameras) to be mounted on the HAP and trained on a target. This will generally require camera control from a user on the ground. Picture digitisation and compression of the video signal will be required at the HAP. The gateway data link (HAP to ground base station backhaul) can be at any frequency band, assuming the required service availability can be met. The aggregate data rate, HAP to ground, will depend on the number of cameras involved, the picture content (in particular the movement), the quality required and the coding employed. It seems likely that the HAP might include several cameras, each tracking a ground based event, so picture content will include movement. It is likely that a high resolution, high quality image will be required from each camera. On-board statistical multiplexing could be used to further reduce the aggregate data rate, which is estimated at up to 155 Mbit/s.

Video surveillance by police forces European police forces are increasingly using video surveillance from helicopters or fixed wing aircraft to fight crime or to manage incidents. Helicopters are especially useful in tracking vehicles that are thought to be stolen or to have been used in crime. Where the drivers of such vehicles refuse to stop when challenged by police officers, dangerous situations can occur. Pursuit by police vehicles can lead to very hazardous situations. The criminal can feel under pressure from a closely following police vehicle and can consequently increase speed, take high risks and generally put many lives in jeopardy. If a police helicopter is on the scene, it can be used to more covertly track the target, allowing the police vehicle to drop back thereby reducing the pressure on the criminal to drive at excessive speed and take risks. The police can therefore plan ahead and force the vehicle to stop in a safer place under controlled circumstances. Video footage can also help in successful prosecutions, e.g. of dangerous driving, and the helicopter can also monitor the speed of the target vehicle. Police helicopters are also very useful in locating and tracking criminals on foot and in directing officers on the ground to apprehend the suspects. The use of infra-red cameras at night is of great benefit in these situations. Aerial surveillance is also useful for public safety (crowd control, incident monitoring) and traffic control. Although very useful, police helicopters suffer several disadvantages. •

They take time to arrive at the scene of the incident.

•

They have a finite endurance, and may have to leave a prolonged surveillance operation.

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•

They are noisy, and criminals are made aware of their presence. Although helicopters can often covertly track a vehicle at high speeds, their noise draws attention when the vehicle stops or the occupants decamp.

•

The noise of helicopter surveillance, especially when hovering at night over housing estates, causes irritation to law-abiding members of the public

A combination of surveillance from HAPs and helicopters might prove a winning solution. HAPs could provide an instant response to a surveillance situation, prior to the arrival of a helicopter on station. HAPs could also be used in general covert surveillance, acting as a deterrent to crime. Although HAPs may have a role to play, the disadvantages of cloud cover and look angle must not be under estimated. Additionally, there may be public resistance to the notion of a spy camera in the sky, able to pry on citizens in the privacy of their own back gardens (even though the military probably have this ability already).

Video surveillance for security Terrestrial security cameras are extremely useful and widespread, but there may be an opportunity for covert HAPs surveillance, for example at large outdoor installations like airports and docks.

Video surveillance for road traffic monitoring and control Various methods of traffic monitoring and control are in service within Europe. Fixed cameras and electronic monitoring devices are often located on bridges and other vantage points, especially in known trouble spots. Helicopters and fixed wing aircraft are also used to survey and report on traffic flows. HAPs may have a complementary role to play.

Infra-red and Radar surveillance Infra red and radar surveillance have applications in earth observation (ecology) and weather forecasting, but the primary applications are military.

Remote monitoring and control HAPs could be used to collect data from remote sensors for environmental monitoring, and transmissions from the HAPs could be used for control. These applications were highlighted in the HeliNet project [10], [49], [50]. However, the applications are mainly of low data rate, and are therefore not applicable to CAMPANINA.

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APPENDIX 2 : UMTS The CAPANINA project is aimed at broadband applications using mm wave frequencies. This precludes a study of direct communication from the HAPs to UMTS handsets. Any CAPANINA association with UMTS is therefore limited to a backhaul between a cellular transmitter/receiver and central base station electronics, and this is discussed in the main document (Section 5.14). However, since a commonly cited HAP application is for direct communication between the HAP and user handsets [53], this application is expounded below. A role for HAPs could be to act as an aerial base station for UMTS (e.g. 3-G mobile). HAPs may have a role to play in extending 3-G coverage rapidly to new areas in advance of a terrestrial solution. Even where terrestrial base stations are considered more cost-effective than the HAP solution, HAPs can still provide a quick start-up, and can then be easily and cheaply moved on to new coverage areas once the terrestrial solution in a particular location becomes established. HAPs could also provide temporary UMTS coverage for disaster sites and for venues experiencing high temporary UMTS usage, such as the Olympics

3-G applications carried by HAPs The future will see a continued convergence of communication services such as voice, Internet data and video into an integrated services (probably IP-based) network. 3-G mobile terminals are likely to be supplied with several levels of capability and complexity, dependent on price. A 3-G terminal might combine features such as a telephone, a (still) camera, a video-camera, a video receiver, a personal stereo, a radio, etc. The more advanced pocket terminals will include a pocket computer and media player software. This will allow, amongst other things, video streaming. In summary, HAPs supplied 3-G services could include: •

Voice and video phones

•

Imaging and picture transfers

•

White board for character display (evolved SMS text messages)

•

Internet access and associated applications, including e-mail, FTP, etc.

•

Location based services

•

Broadcast/Multicast based services

•

Games

•

Personal (from handset) database, synchronised calendars, etc.

Advantage of HAPs over satellite for UMTS Satellite is sometimes used for mobile services, especially where the terrestrial infrastructure is insufficiently developed to support a terrestrial solution. Unfortunately, even at L-band, the link budget of satellite means that service tends to be available only with line of sight of the satellite, and is unavailable within buildings. The link-budget advantage of HAPs means that the provision of service to unmodified UMTS handsets is far more practicable than from satellite, especially where handsets are located inside buildings.

Broadcast / Multicast to UMTS handsets HAPs can be very efficiently used to broadcast or multicast data to handsets. A service mix could be considered whereby HAPs is used for broadcast/multicast traffic to handsets, with peer to peer traffic carried by terrestrial base stations, thereby liberating base station capacity. Broadcast applications to UMTS handsets could include: •

National TV stations

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•

Pay TV stations (e.g. cable and satellite)

•

Video streaming

•

Pushed content based on location or profile


Implementation options The UMTS base station hardware could be physically located on the ground, with the HAP acting as a transparent relay to mobiles. Alternatively, the HAP could include on-board processing. The technology should be transparent to the user, and the handset should be capable of operating either to HAPs or to local base stations. This assumes that the user link will operate in L-band and Sband, where UMTS licences are applied, in order to be interoperable with standard UMTS handsets. There are likely to be significant regulatory and technical issues here. For example, the power of a standard UMTS handset may be insufficient for the HAP link budget. The gateway links (ground base station to HAP backhaul) are open to any frequency band, assuming the required service availability can be met.

UMTS Base Station Backhaul HAPs could be used to provide the backhaul between UMTS base stations and the core network. This application would be of value in areas of poor terrestrial infrastructure. HAPs could be efficiently used to broadcast or multicast data to base stations. A service mix could be considered whereby HAPs is used for broadcast/multicast traffic to base stations, with point to point traffic carried by the terrestrial network, thereby relieving pressure on the terrestrial infrastructure. •

Broadcast applications to 3-G handsets could include:

•

National TV stations

•

Pay TV stations (e.g. cable and satellite)

•

Video streaming

•

Pushed content based on location or profile

End of Document

29th Jan 2004


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