1、 International Telecommunication Union ITU-T G.657TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media and optical systems characteristics Optical fibre cables Characteristics of a bending-loss insensitive
2、 single-mode optical fibre and cable for the access network Recommendation ITU-T G.657 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSM
3、ISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTE
4、LEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 General G.600G.609 Symmetric cable pairs G.610G.619 Land coaxial cable pairs G.620G.629 Submarine cables G.630G.639 Free space optical systems G.640G.649 Optical fibre cables G.650G.659Characteris
5、tics of optical components and subsystems G.660G.679 Characteristics of optical systems G.680G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1
6、000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.657 (10/2012) i Recommendation ITU-T
7、 G.657 Characteristics of a bending-loss insensitive single-mode optical fibre and cable for the access network Summary Worldwide, technologies for broadband access networks are advancing rapidly. Among these, the technology applying single-mode fibre provides for a high-capacity transmission medium
8、 which can answer the growing demand for broadband services. The experience with the installation and operation of single-mode fibre and cable-based networks is huge, and Recommendation ITU-T G.652 which describes its characteristics has been adapted to this experience. Nevertheless, the specific us
9、e in an optical access network puts different demands on the fibre and cable which impacts its optimal performance characteristics. Differences with respect to the use in the general transport network are mainly due to the high density network of distribution and drop cables in the access network. T
10、he limited space and the many manipulations ask for operator-friendly fibre performance and low bending sensitivity. In addition, the cabling in the crowded telecom offices where space is a limiting factor has to be improved accordingly. It is the aim of Recommendation ITU-T G.657 to support this op
11、timization by recommending strongly improved bending performance compared with the existing ITU-T G.652 single-mode fibre and cables. This is done by means of two categories of single-mode fibres, one of which, category A, is fully compliant with the ITU-T G.652 single-mode fibres and can be deploye
12、d throughout the access network. The other, category B, is not necessarily compliant with Recommendation ITU-T G.652 but is capable of low values of macrobending losses at very low bend radii and is intended for use inside buildings or near buildings (e.g., outside building riser cabling). These cat
13、egory B fibres are system compatible with ITU-T G.657.A (and ITU-T G.652.D) fibres in access networks. This third edition of Recommendation ITU-T G.657 includes several modifications in particular concerning category B fibres. Also the new Appendix I (agreed in 2010 and published as Amendment 1 (06/
14、2010) has been introduced with revisions. History Edition Recommendation Approval Study Group 1.0 ITU-T G.657 2006-12-14 15 2.0 ITU-T G.657 2009-11-13 15 2.1 ITU-T G.657 (2009) Amd. 1 2010-06-11 15 3.0 ITU-T G.657 2012-10-29 15 ii Rec. ITU-T G.657 (10/2012) FOREWORD The International Telecommunicati
15、on 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 tariff quest
16、ions 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 Recommendations
17、 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 Recommendation, t
18、he 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., interoperability or a
19、pplicability) 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 compliance wi
20、th 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, validity or appl
21、icability 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 required to impl
22、ement 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 2013 All rights reserved. No part of this publication may be reproduced, by any m
23、eans whatsoever, without the prior written permission of ITU. Rec. ITU-T G.657 (10/2012) iii Table of Contents Page 1 Scope 1 2 References. 2 3 Terms and definitions . 2 4 Abbreviations and acronyms 2 5 Fibre attributes 2 5.1 Mode field diameter . 3 5.2 Cladding diameter 3 5.3 Core concentricity err
24、or 3 5.4 Non-circularity . 3 5.5 Cut-off wavelength . 3 5.6 Macrobending loss 3 5.7 Material properties of the fibre . 4 5.8 Refractive index profile 5 5.9 Longitudinal uniformity of chromatic dispersion . 5 5.10 Chromatic dispersion coefficient 5 6 Cable attributes . 5 6.1 Attenuation coefficient .
25、 6 6.2 Polarization mode dispersion coefficient . 6 7 Tables of recommended values 6 Appendix I Lifetime expectation in case of small radius bending of single-mode fibre 11 I.1 Introduction 11 I.2 General aspects of failure characteristics under small radius bending . 11 I.3 Network and network fail
26、ure examples 13 I.4 Fibre lifetime considerations 13 I.5 Conclusion 15 Bibliography. 16 iv Rec. ITU-T G.657 (10/2012) Introduction Worldwide, technologies for broadband access networks are advancing rapidly. Among these, the technology applying single-mode fibre provides for a high-capacity transmis
27、sion medium which can answer the growing demand for broadband services. The experience with the installation and operation of single-mode fibre and cable-based networks is huge, and Recommendation ITU-T G.652 which describes its characteristics has been adapted to this experience. Nevertheless, the
28、specific use in an optical access network puts different demands on the fibre and cable. Due to dense distribution and drop-cable network, limited space and the many manipulations in this part of the network, fibre and cable requirements may be optimized differently from their use in a general trans
29、port network. It is the aim of this Recommendation to support this optimization by recommending different attribute values for the existing ITU-T G.652 single-mode fibre and cables and by recommending other categories of single-mode fibre types. As for the network structures in which the single-mode
30、 optical fibre cable is used, users are referred to the extensive information that is available in the references listed in the bibliography. Rec. ITU-T G.657 (10/2012) 1 Recommendation ITU-T G.657 Characteristics of a bending-loss insensitive single-mode optical fibre and cable for the access netwo
31、rk 1 Scope This Recommendation describes two categories of single-mode optical fibre cable which are suitable for use in access networks, including inside buildings at the end of these networks. Both categories A and B contain two subcategories which differ in macrobending loss. Category A fibres ar
32、e optimized for reduced macrobending loss and tighter dimensional specifications compared to ITU-T G.652.D fibres and can be deployed throughout the access network. These fibres are suitable to be used in the O, E, S, C and L-band (i.e., throughout the 1260 to 1625 nm range). Fibres and requirements
33、 in this category are a subset of ITU-T G.652.D and therefore compliant1with ITU-T G.652.D fibres and have the same transmission and interconnection properties. Subcategory ITU-T G.657.A1 fibres are appropriate for a minimum design radius of 10 mm. Subcategory ITU-T G.657.A2 fibres are appropriate f
34、or a minimum design radius of 7.5 mm. Category B fibres are optimized for further reduced macrobending loss and therefore are capable of being used at very low values of bend radius. These fibres are for short reach distances (less than 1000 m) at the end of access networks, in particular inside bui
35、ldings or near buildings (e.g., outside building riser cabling). The application length of ITU-T G.657.B fibre depends on the deployment strategy of each network operator. These fibres are suitable for use in the O, E, S, C and L-band (i.e., throughout the 1260 to 1625 nm range). Category B fibres a
36、re not necessarily compliant with ITU-T G.652.D in terms of chromatic dispersion coefficient and PMD specifications. These fibres however, are system compatible2with ITU-T G.657.A (and ITU-T G.652.D) fibres in access networks. Subcategory ITU-T G.657.B2 fibres are appropriate for a minimum design ra
37、dius of 7.5 mm. Subcategory ITU-T G.657.B3 fibres are appropriate for a minimum design radius of 5 mm. The meaning of the terms used in this Recommendation and the guidelines to be followed in the measurement to verify the various characteristics are given in ITU-T G.650.1 and ITU-T G.650.2. The cha
38、racteristics of these fibre categories, including the definitions of the relevant parameters, their test methods and relevant values, will be refined as studies and experience progress. _ 1Compliance here means adherence to the referenced Recommendation (ITU-T G.652, category D) meeting or exceeding
39、 the values of the specified attributes. 2Compatibility means here that the product in this category will introduce negligible system impairment or deployment issues but may not be compliant to the referenced Recommendation (ITU-T G.652, category D). 2 Rec. ITU-T G.657 (10/2012) 2 References The fol
40、lowing 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 subject to revision; users of this Rec
41、ommendation 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 within this Recommendation does no
42、t give it, as a stand-alone document, the status of a Recommendation. ITU-T G.650.1 Recommendation ITU-T G.650.1 (2010), Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable. ITU-T G.650.2 Recommendation ITU-T G.650.2 (2007), Definitions and test methods f
43、or statistical and non-linear related attributes of single-mode fibre and cable. ITU-T G.652 Recommendation ITU-T G.652 (2009), Characteristics of a single-mode optical fibre and cable. ITU-T L.59 Recommendation ITU-T L.59 (2008), Optical fibre cables for indoor applications. IEC 60793-1-47 IEC 6079
44、3-1-47 (2009), Optical fibres Part 1-47: Measurement methods and test procedures Macrobending loss. 3 Terms and definitions For the purposes of this Recommendation, the definitions and the guidelines to be followed in the measurement to verify the various characteristics are given in ITU-T G.650.1 a
45、nd ITU-T G.650.2. Values shall be rounded to the number of digits given in the tables of recommended values before conformance is evaluated. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: DGD Differential Group Delay MDU Multi-dwelling Unit PMD Polari
46、zation Mode Dispersion 5 Fibre attributes The optical fibre characteristics that provide the essential design framework for fibre manufacture, system design and use in outside plant networks are recommended in ITU-T G.652. In this clause, the emphasis is on attributes that optimize the fibre and cab
47、le for its use in broadband optical access networks, especially its improved macrobending behaviour which supports small volume fibre managements systems and low radius mounting in telecom offices and customer premises in apartment buildings and single dwelling houses. Also, for completeness, those
48、characteristics of the fibre that provide a minimum essential design framework for fibre manufacture are recommended in this clause. Ranges or limits on values are presented in the tables of clause 7. Of these, cable manufacture or installation may significantly affect the cabled fibre cut-off wavel
49、ength and PMD. Otherwise, the recommended characteristics will apply equally to individual fibres, fibres incorporated into a cable wound on a drum and fibres in an installed cable. Rec. ITU-T G.657 (10/2012) 3 5.1 Mode field diameter Both a nominal value and tolerance about that nominal value shall be specified at 1310 nm. The nominal value that is specified shall be within the range found in clause 7. The specified tolerance shall not exceed the value in clause 7. The deviation from nominal shall not
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