1、 International Telecommunication Union ITU-T L.71TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2008) SERIES L: CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT Design, construction, and installation of network cables for broadband access including metalli
2、c networks connected to optical fibre networks Recommendation ITU-T L.71 Rec. ITU-T L.71 (01/2008) i Recommendation ITU-T L.71 Design, construction, and installation of network cables for broadband access including metallic networks connected to optical fibre networks Summary Recommendation ITU-T L.
3、71 deals with the design, construction and installation of network cables for broadband access. To design the network of metallic cables for broadband access, firstly the number of lines to be provided, the type of access system such as xDSL to be installed, and the availability of existing copper n
4、etworks may be considered. This Recommendation includes a design process and construction examples. Source Recommendation ITU-T L.71 was approved on 8 January 2008 by ITU-T Study Group 6 (2005-2008) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T L.71 (01/2008) FOREWORD The International Tel
5、ecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and
6、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 four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Rec
7、ommendations 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, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recom
8、mendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperab
9、ility or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that com
10、pliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validi
11、ty or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be requir
12、ed to implement this Recommendation. 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 2008 All rights reserved. No part of this publication may be reproduced
13、, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T L.71 (01/2008) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 1 4 Abbreviations and acronyms 1 5 Conventions 2 6 Design. 2 6.1 Design principles 2 6.2 Flow of copper network design 2 7 Construction and inst
14、allation 6 Appendix I Korean experience on the construction and installation of outdoor structures for broadband access. 7 I.1 BB-C (cabinet for broadband service) 7 I.2 BB-S (shelter for broadband service). 9 I.3 BB-M (manhole for broadband service). 10 Bibliography. 13 Rec. ITU-T L.71 (01/2008) 1
15、Recommendation ITU-T L.71 Design, construction, and installation of network cables for broadband access including metallic networks connected to optical fibre networks 1 Scope This Recommendation discusses networks of metallic cables for broadband access including those used to connect to optical fi
16、bre networks. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subj
17、ect to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document
18、within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T K.26 Recommendation ITU-T K.26 (2008), Protection of telecommunication lines against harmful effects from electric power and electrified railway lines. ITU-T L.1 Recommendation ITU-T L.1 (19
19、88), Construction, installation and protection of telecommunication cables in public networks. ITU-T L.19 Recommendation ITU-T L.19 (2003), Multi-pair copper network cable supporting shared multiple services such as POTS, ISDN and xDSL. ITU-T L.44 Recommendation ITU-T L.44 (2000), Electric power sup
20、ply for equipment installed as outside plant. ITU-T L.63 Recommendation ITU-T L.63 (2004), Safety procedures for outdoor installations. 3 Definitions None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: CAPEX Capital Expenditure CO Central Office DSLA
21、M Digital Subscriber Line Access Multiplexer FTTx Fibre to the x (C: Curb, O: Office, B: Building, N: Node, P: Premises, H: Home) MDF Main Distribution Frame NIU Network Interface Unit ODF Optical Distribution Frame OPEX Operating Expenses PON Passive Optical Network STB Set-Top Box 2 Rec. ITU-T L.7
22、1 (01/2008) 5 Conventions None. 6 Design Copper networks should be designed to be resilient to environmental conditions such as rain, snow and windstorms since they are installed mainly in outdoor environments. Also, other construction information such as power induction and electrical corrosion sho
23、uld be taken into account based on the collaborative investigations with other related organizations. Especially, topographical characteristics by city and road planning, facilities belonging to other organizations, and transportation conditions also have to be considered because copper networks are
24、 widely distributed according to various customers demands. 6.1 Design principles 6.1.1 Technical condition In order to provide fast, accurate and reliable services to the customers, transmission loss and DC resistance limits should be addressed to ensure compliance with related standards. 6.1.2 Eco
25、nomics The shortest routes, existing outside plant facilities, materials, etc., shall be considered. In case of FTTx deployment, the location of outdoor cabinets shall be taken into account because copper network designs need huge capital expenditure and existing copper networks between outdoor cabi
26、nets and subscribers can be used. 6.1.3 Preservation Copper networks should be designed considering natural environmental conditions since their facilities are installed mainly in outdoor environments. Additionally, the configuration for easy maintenance as well as OPEX and CAPEX shall be taken into
27、 account from the viewpoint of network topology such as cable route decisions. 6.1.4 Reliability Reliability should be considered in order to meet the customers needs. Especially, the capacity of transmission lines, mechanical properties of structures, regional conditions and city evolution trends h
28、ave to be taken into account. 6.1.5 Construction The total construction period considering material delivery and work procedures, including cross-connection of operating pairs, shall be also examined. 6.2 Flow of copper network design Copper network designs comprise “preliminary design“ and “final d
29、esign“. Figure 1 shows the work flow of copper network design. Rec. ITU-T L.71 (01/2008) 3 Decision on the number of lines, type of access system to be installed, and availability of existing copper network Preliminary design Final design Reporting to construction department Figure 1 Flow for copper
30、 network design 6.2.1 Preliminary design 6.2.1.1 Flow for preliminary design Figure 2 shows the flow chart for preliminary design. To design a copper network for broadband access, the type of access technology shall be decided first. Copper networks may be deployed variously according to the access
31、technology. Technology development makes the access loop to deep fibre architectures that shorten or eliminate copper loop length as shown in Figure 3. FTTx technologies replace the copper loop with fibre running all the way to the subscriber residence, or extend DSL access equipment to within hundr
32、eds of metres of the home, the distance at which copper drops can deliver tens of Mbit/s. In case of ADSL deployment, digital subscriber line access multiplexers (DSLAMs) may be located at optical nodes where outdoor cabinets shall be used, 1 to 2 km from the customer premises to provide the higher
33、speed of service. The special digital cables that have high crosstalk performance can be used when installing new copper cables. Decision on access technology Decision on the number of copper lines to be provided to the subscriber Information collection and preparation, including existing copper net
34、work for basic design Confirmation of preliminary design Figure 2 Flow of preliminary design 4 Rec. ITU-T L.71 (01/2008) L.71(08)_F03Optic cableCoppercableHandholeC.O.Optical splitterConduitManholeManholeOptical closureFTTCONUONUCoppercableCross-connectterminalONUCommercialbuildingPONONUxDSLFTTxWide
35、bandterminal equipmentODF MDFNIUSTBFigure 3 FTTx access network configuration 6.2.1.2 Information collection a) Telecommunication facilities: District map Demanded number of lines and existing lines for fixed distribution area Map of cable lines including underground conduits or ducts Drawing of mai
36、n distribution frame (MDF) Status of distribution area b) Others: Other underground facilities such as gas or water pipes Plans to build roads, watercourses, sewers, housing complexes, railways, power lines, waterworks, bridges, etc. Effects from power line, lightning, electrical corrosion Harmful e
37、ffects from sea wind or environmental pollution Gas leakage and lack of oxygen in manholes Weather statistics 6.2.1.3 Preparation of preliminary design specification a) Cables networks: Boundary of residential area Boundary of fixed distribution area Conductor diameter and feeder cable counts Rec. I
38、TU-T L.71 (01/2008) 5 Demanded cable counts for fixed distribution area ONU location b) Ducts: Usage status of manholes Existing duct or conduit routes Sections to be enlarged or improved c) Central office facilities: Configuration of terminating cables Drawing of operating rooms d) Preparation of t
39、he design drawing 6.2.1.4 Contents of preliminary design Purpose Summary of construction expenses Main resources list and amounts Main processes for construction Construction methods Construction period Meeting records of discussions with related agencies Preliminary design drawing Others 6.2.2 Fina
40、l design 6.2.2.1 Flow for final design The flow for final design is shown in Figure 4. Plan for final design Decision of process Confirmation for cable route, cable count, outdoor facility location, how to use existing lines, etc. Cost estimation Completion Figure 4 Flow for final design 6 Rec. ITU-
41、T L.71 (01/2008) 6.2.2.2 Basic rules for final design Before completion of the final design, the following items shall be considered: Final number of lines to meet demand Confirmation of whether the fixed distribution areas are allocated appropriately Changes after preliminary design Others 6.2.2.3
42、Final design a) Decision of optical node location If copper cable is connected to an optical fibre network, the optimal location of optical nodes should be selected. To construct the optical nodes such as ONU, outdoor cabinets can be used. The outdoor cabinets should be installed considering the siz
43、e of the cabinet, occupation area and the risk of flood damage. Also, it can be considered whether to purchase or rent the place to install outdoor cabinets. A series of these processes can minimize the OPEX for environmental damage or moving of cabinets in future. If existing copper cables are used
44、, testing may be needed. b) Conductor diameter of copper cable The minimum conductor diameter may be used within the range of acceptable maximum line loss according to the broadband access systems. The acceptable maximum insertion loss of ISDN/xDSL systems, typical DC resistance and line loss on cop
45、per pairs, and typical reach for ISDN/xDSL services, are shown in Tables 3, 4 and 5 of ITU-T L.19, respectively. If a new copper cable is connected to an existing copper cable, the total line loss should be evaluated. The number of bridged taps may be also minimized. c) Power influence calculation I
46、nduced voltage and noise on copper pairs running parallel to power lines shall be calculated and countermeasure should be established according to the related regulation. d) Preparation of final design drawing 6.2.2.4 Contents of final design Cover and contents Introduction General specification (if
47、 needed, include exceptional specification) Time schedule Number of persons Estimated cost of construction List of construction materials Design drawing Others 7 Construction and installation Construction and installation of copper networks are shown in ITU-T L.1, which is a placeholder pointing to
48、b-ITU-T Handbook. If there is some equipment (e.g., ONU or remote-deployed xDSL) needing a power supply, ITU-T L.44 contain provisions. For safety procedures applicable to outdoor installations, refer to ITU-T L.63. Rec. ITU-T L.71 (01/2008) 7 Appendix I Korean experience on the construction and ins
49、tallation of outdoor structures for broadband access (This appendix does not form an integral part of this Recommendation) Introduction This appendix contains information about the construction and installation of outdoor structures containing electronic equipment installed at the roadside or underground to provide high-speed broadband access in an FTTC network. I.1 BB-C (cabinet for broadband service) I.1.1 Structure A BB-C can provide broadband access to a maximum of 120
