1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T Series L TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Supplement 31 (10/2016) SERIES L: ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEM
2、ENTS OF OUTSIDE PLANT ITU-T L.1700 Setting up a low-cost sustainable telecommunication network for rural communications in developing countries using satellite systems ITU-T L-series Recommendations Supplement 31 ITU-T L-SERIES RECOMMENDATIONS ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EF
3、FICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT OPTICAL FIBRE CABLES Cable structure and characteristics L.100L.124 Cable evaluation L.125L.149 Guidance and installation technique L.150L.199 OPTICAL INFRASTRUCTURES Infrastructure including node eleme
4、nt (except cables) L.200L.249 General aspects and network design L.250L.299 MAINTENANCE AND OPERATION Optical fibre cable maintenance L.300L.329 Infrastructure maintenance L.330L.349 Operation support and infrastructure management L.350L.379 Disaster management L.380L.399 PASSIVE OPTICAL DEVICES L.4
5、00L.429 MARINIZED TERRESTRIAL CABLES L.430L.449 For further details, please refer to the list of ITU-T Recommendations. L series Supplement 31 (10/2016) i Supplement 31 to ITU-T L-series Recommendations ITU-T L.1700 Setting up a low-cost sustainable telecommunication network for rural communications
6、 in developing countries using satellite systems Summary Supplement 31 to ITU-T L-series Recommendations provides requirements for a low-cost sustainable telecommunication infrastructure for rural communications in developing countries with focus on very small aperture antennas for users. It provide
7、s details on the generic requirements set out in Recommendation ITU-T L.1700. These requirements are drawn up taking account of examples of best practices from systems already in use and the special needs of remote communities, such as cost and the lack of access to grid electricity. Broadband satel
8、lite is available in many countries at an entry cost comparable or even lower than terrestrial systems. To close the digital divide, developing countries should consider using broadband satellite. This will provide coverage to all rural and remote locations. History Edition Recommendation Approval S
9、tudy Group Unique ID* 1.0 ITU-T L Suppl. 31 2016-10-14 5 11.1002/1000/13154 Keywords Broadband satellite network, Coverage, VSAT. * To access the Supplement, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Supplements unique ID. For example, http:/handle.
10、itu.int/11.1002/1000/11830-en. ii L series Supplement 31 (10/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector
11、 (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every f
12、our years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, t
13、he necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this publication, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this publication is voluntary. Howev
14、er, the publication may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the publication is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equiva
15、lents are used to express requirements. The use of such words does not suggest that compliance with the publication is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this publication may involve the use of a claimed In
16、tellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the publication development process. As of the date of approval of this publication, ITU had not received
17、notice of intellectual property, protected by patents, which may be required to implement this publication. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU
18、2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. L series Supplement 31 (10/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 4 Abbreviations and acronyms 1 5 Conventions 1 6 Use
19、 of satellite systems to provide communications in remote areas 1 6.1 Bidirectional satellite 3 6.2 Geostationary Earth orbit satellite systems: Analysis against requirements identified in ITU-T L.1700 4 Bibliography. 9 iv L series Supplement 31 (10/2016) Introduction Very small aperture terminal (V
20、SAT) technology has been available for Internet access since the early 1990s b-GVF, 2003. The widespread use of VSATs has been limited by factors such as: the round trip delay being longer than that for terrestrial systems, high capital cost of the satellite network, higher electricity power require
21、ments of VSAT terminals compared with terrestrial alternatives and lower bandwidth per link than terrestrial alternatives. Many of the shortcomings have been increasingly addressed by advances in modern satellite broadband systems derived from earlier VSATs. The aim of this Supplement is to provide
22、an up-to-date review of the technology with focus on geostationary satellite systems. VSATs comprise the only technology which offers ubiquitous coverage from day one. While VSATs may not be able to compete with terrestrial technology for delay-sensitive traffic such as some games and other interact
23、ive applications, it is capable of narrowing the digital divide by providing Internet access to remote communities for the first time. These communities will therefore be able to exploit the Internet using a wide range of online services and through it develop the local economy. Once sufficient weal
24、th is generated, the additional investment needed for dedicated terrestrial links, such as those described in other Supplements in the L.1700 series, can be found. L series Supplement 31 (10/2016) 1 Supplement 31 to ITU-T L-series Recommendations ITU-T L.1700 Setting up a low-cost sustainable teleco
25、mmunication network for rural communications in developing countries using satellite systems 1 Scope This Supplement addresses satellite systems that provide low-cost deployable broadband services in remote regions. The generic requirements set out in ITU-T L.1700 are addressed with reference to VSA
26、T systems, including options for providing “off-grid“ electricity. The focus is on example systems already in use or novel systems already commissioned for deployment. 2 References ITU-T L.1700 Recommendation ITU-T L.1700 (2016), Requirements and framework for low-cost sustainable telecommunications
27、 infrastructure for rural communications in developing countries. 3 Definitions None. 4 Abbreviations and acronyms This Supplement uses the following abbreviations and acronyms: GEOS Geostationary Earth Orbit Satellite GW Gateway HTS High Throughput Satellite LEOS Low Earth Orbit Satellite LTE Long-
28、Term Evolution MEOS Medium Earth Orbit Satellite MTBF Mean Time Between Failures NCC Network Control Centre NMS Network Management System RF Radio Frequency SCC Satellite Control Centre VoIP Voice over Internet Protocol VSAT Very Small Aperture Terminal 5 Conventions None. 6 Use of satellite systems
29、 to provide communications in remote areas Figure 1 shows the terminology commonly used in satellite systems overlaid in red on the generic network. In a commercial system, an additional satellite would be deployed to act as a standby. 2 L series Supplement 31 (10/2016) Figure 1 Generic network of I
30、TU-T L.1700, showing satellite network elements (in red) Satellite-based systems have the following advantages compared with a fixed or mobile (terrestrial) telecommunication infrastructure: coverage of a wide area compared with fixed or mobile systems; rapid deployment, using satellites already in
31、orbit; ease of setting up and flexible reconfiguration; very cost competitive with terrestrial systems, using multi-spot beam satellites; relatively low cost for a particular coverage area, and can have lower green house gas emissions compared to terrestrial systems. Note that because satellite-base
32、d systems can be set up and configured rapidly, they are particularly suited to responding to disaster situations. this is the topic of the b-ITU, 2006 handbook of emergency and disaster relief, which includes, for example, portable satellite terminals as an integral part of the document. The follow
33、ing types of communications satellite systems are available. Geostationary Earth orbit satellite (GEOS) systems orbit at an altitude of 35,786 km and are in synchrony with the rotation of the Earth, which eliminates the need for VSAT antenna tracking and allows fixed antennas to be used at the user
34、terminal. GEOS systems are used for commercial telecommunications, broadband Internet service and broadcast services. They have a relatively high latency (round trip delay) compared with low Earth orbit satellite (LEOS) or terrestrial systems and so cannot be used where short data response times are
35、 required. LEOS systems are used for telecommunication services, such as semi-mobile telephony in remote locations, but are not known to be used for broadband fixed access, because of tracking difficulties. These have a much lower latency, but require many more satellites, more frequent handover bet
36、ween satellites, and a more complicated and higher cost system. There are some plans to develop LEOS systems for commercial service. Although used for narrow-band services with an omnidirectional antenna, for broadband services a LEOS system requires a tracking antenna, which adds to the cost. Mediu
37、m earth orbit satellite (MEOS) systems orbit at altitudes between 2 000 and 35 786 km, are similar to LEOS in functionality and are used for fibre-like services to locations, such as oceanic islands and large cruise liners. A MEOS system requires a tracking antenna, which adds to the cost. L series
38、Supplement 31 (10/2016) 3 6.1 Bidirectional satellite Figure 2 shows the main components of a two-way service satellite network architecture with: the satellite platform; the satellite terminals composed of the antenna system (dish), the radio frequency (RF) part (including power amplifier, low nois
39、e amplifier and filters) and the modem implementing the baseband processing of the satellite radio interface; the Hub that includes both a network control centre (NCC) to manage the in-orbit radio resources and a gateway (GW) with its antenna system, the RF part and a set of modems. Figure 2 Two-way
40、 service satellite network architecture A geostationary-based satellite access network typically comprises the following parts. A space segment composed of one or more high throughput satellites (HTSs) in geostationary orbit. The satellite connects the GWs of the ground segment to the user terminals
41、, by means of a set of feeder and user beams. A ground segment which includes the following. A main NCC that has the responsibility to control and synchronize the overall network. A main network management system (NMS) that handles the management of the resources in the network. 4 L series Supplemen
42、t 31 (10/2016) A satellite control centre (SCC) to monitor and control the space segment. A set of GWs that are in charge of transmitting and receiving data, control and management traffic to or from the user terminals. Each GW is equipped with its own local NCC/NMS to ensure their individuality and
43、 their operation sequence in case of a total system malfunction originating from a main NCC/NMS failure. A user segment which is composed of a set of user terminals. 6.2 Geostationary Earth orbit satellite systems: Analysis against requirements identified in ITU-T L.1700 The following requirements w
44、ere identified in ITU-T L.1700. It is assumed that any investment in satellites will take advantage of the latest HTSs b-Thaicom, 2012. 6.2.1 Cost This covers the system cost per user; cost per service area, cost per megabit and cost per user. For HTS systems, the cost of the satellite launch and pa
45、yload is projected to be US$600 million in year 2020 b-ITSO, 2016. “Most communications satellite projects range from $300$600 million, including the spacecraft, launch and launch insurance. These are typically high, up-front and fixed costs, with unique risk factors, which are typically recouped ov
46、er the expected 15-year lifetime of the satellite.“ (b-SIA, 2014, p. 2) This compares favourably with terrestrial alternatives, depending on whether a reserve satellite is required if the initial satellite fails. The cost of the system is recovered from the large number of users, depending on the ca
47、pacity or bandwidth required by individual users. (Note that other users of transponders may be businesses who will contribute to the overall costs.) For individuals, such as those owning smartphones on mobile networks, this is often quoted in gigabytes per month, whereas for fixed subscribers it is
48、 quoted as megabits per second, but may also have a monthly usage allowance measured in gigabytes. Fixed broadband example. A 45 Gbit/s satellite provides 84 spot beams of 471 Mbit/s per spot beam b-Little, 2015b-Gunter, 2017. At low utilization, based upon long-term evolution (LTE) practice b-Heath
49、, 2010, each spot beam could typically cover 3 000 users at an average of 0.157 Mbit/s per user and with a typical data concentration factor of 300 could burst at up to 47.1 Mbit/s. Such a broadband satellite system with 84 spot beams could support 252 000 users. If the VSAT satellite user system cost $450 and over the 15 year life cycle the operating cost is also $450, then in 1 year $60 million would need to be recovered to break even. This averages at $238 per user per
