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 G TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Supplement 59 (09/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Guidance on optical fibre and cable reliability ITU-T G-series Recommen
2、dations Supplement 59 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-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATI
3、ONAL 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 RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTI
4、CAL SYSTEMS CHARACTERISTICS G.600G.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.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DA
5、TA 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. G series Supplement 59 (09/2016) i Supplement 59 to ITU-T G-series Recommendations Guidance on optical fibre
6、and cable reliability Summary Supplement 59 to ITU-T G-series Recommendations provides guidance regarding the long term reliability of cabled optical fibres. This Supplement uses currently accepted models combined with current experience to describe items that can impact the performance of an optica
7、l fibre over time. The document describes optical reliability for fibres, mechanical reliability for fibres and describes how optical cables impact these properties. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G Suppl. 59 2016-09-30 15 11.1002/1000/13123 * To access the
8、Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii G series Supplement 59 (09/2016) FOREWORD The International Telecommunication Union (ITU) is the United
9、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 questions and issuing Recommendati
10、ons 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 on these topics. The approva
11、l 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 publication, the expression “Administration“ i
12、s used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this publication is voluntary. However, the publication may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the
13、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 equivalents are used to express requirements. The use of such words does not suggest that compliance with the publication is required of any par
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16、ioned 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 2016 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of
17、ITU. G series Supplement 59 (09/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 4 Abbreviations and acronyms 1 5 Conventions 1 6 General comments on reliability . 1 7 Optical reliability 3 7.1 Bending loss . 3 7.2 Hydrogen 4 7.3 Impact of nuclear radiation . 5 7.4 Atten
18、uation stability . 5 8 Mechanical reliability . 6 8.1 General comments on mechanical strength of optical fibres 6 8.2 Power law theory 7 8.3 The time to failure or fibre lifetime is often the parameter of interest. 8 8.4 Static and dynamic stress corrosion parameter and impact on reliability 8 8.5 R
19、elationship between proof stress and proof-testing on reliability 9 8.6 Handleability of optical fibre 9 8.7 Test proceedures that measure aspects of mechanical reliability . 9 9 Strain due to bends tension, to axial tension or a combination of the two mechanisms . 9 10 Impact of cable properties on
20、 reliability . 10 10.1 Fibre strain and cable strain 10 10.2 Installation load vs. long term load 10 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
21、and network failure examples 12 I.4 Fibre lifetime considerations 13 I.5 Conclusion 15 Appendix II Long term reliability of deployed optical fibre cables . 16 II.1 Introduction 16 II.2 Factors having an impact on the objectives for the reliability of deployed optical cables 16 II.3 Example of object
22、ives for the reliability of laid optical cables 17 Bibliography. 18 iv G series Supplement 59 (09/2016) Introduction Supplement 59 to the ITU-T G-series Recommendations provides information on long-term reliability of optical fibre and cable. ITU-T establishes optical fibre and cable Recommendations
23、 such as ITU-T G.651.1, ITU-T G.652, ITU-T G.653, ITU-T G.654, ITU-T G.655, ITU-T G.656, and ITU-T G.657. Also, ITU-T standardized optical cables as described in some of the L series Recommendations. This Supplement also provides more detail on optical fibres reliability described in ITU-T G-Sup.40.
24、 G series Supplement 59 (09/2016) 1 Supplement 59 to ITU-T G-series Recommendations Guidance on optical fibre and cable reliability 1 Scope The scope of this Supplement is to give the end user guidance on the long-term performance of optical fibre and cables. Though it is difficult to address all si
25、tuations and to guarantee long-term performances, this supplement helps understand general long-term behaviour of optical fibres and cables and provides guidelines to help the end users minimize the number of mechanical and optical failures during the expected lifetime of the fibre and cable. 2 Refe
26、rences ITU-T G.651.1 Recommendation ITU-T G.651.1 (2007), Characteristics of a 50/125 m multimode graded index optical fibre cable for the optical access network. ITU-T G.652 Recommendation ITU-T G.652 (2016), Characteristics of a single-mode optical fibre and cable. ITU-T G.653 Recommendation ITU-T
27、 G.653 (2010), Characteristics of a dispersion-shifted, single-mode optical fibre and cable. ITU-T G.654 Recommendation ITU-T G.654 (2016), Characteristics of a cut-off shifted single-mode optical fibre and cable. ITU-T G.655 Recommendation ITU-T G.655 (2009), Characteristics of a non-zero dispersio
28、n-shifted single-mode optical fibre and cable. ITU-T G.656 Recommendation ITU-T G.656 (2010), Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport. ITU-T G.657 Recommendation ITU-T G.657 (2016), Characteristics of a bending-loss insensitive single-mode optical
29、 fibre and cable for the access network. ITU-T G-Sup.40 Supplement ITU-T G.Sup40 (2010), Optical fibre and cable Recommendations and standards guideline. ITU-T L.126 Recommendation ITU-T L.126/L.27 (1996), Method for estimating the concentration of hydrogen in optical fibre cables. 3 Definitions Non
30、e. 4 Abbreviations and acronyms None. 5 Conventions None. 6 General comments on reliability Optical cables were first deployed commercially in 1977. Thus, our knowledge of their performance in the field is less than 40 years and much information provided in this Supplement is speculative, although t
31、oday significant spontaneous fibre breakage in these old fibres is not known. Detailed 2 G series Supplement 59 (09/2016) analysis of attenuation characteristics and mechanical attributes for cabled fibre that have been installed for 25 years b-Hopland 1 b-Hopland 2 indicate that the optical propert
32、ies are very stable over time. With this background we can use our accumulated field knowledge combined with accelerated aging to estimate the reliability of optical cables. Reliability falls into two major categories: Mechanical reliability (will the fibre break over the cable lifetime) Optical rel
33、iability (will optical transmission be maintained over the cable lifetime) It is hard to separate optical fibre reliability from optical cable reliability as the two are intimately related, but in this Supplement we will focus primarily on the fibre attributes and how they relate to cabled optical f
34、ibre. General trends in optical transmission must be considered in our evaluation of optical reliability. The general trend is towards more information traveling down optical fibres. Optical cables are trending toward higher fibre counts in smaller optical cables resulting in the potential for more
35、residual strain on the individual optical fibres. There is a trend towards the use of more of the optical spectrum and thus a desire to preserve the attenuation across the full spectrum from 1260 to 1625 nm to allow the most opportunities for bandwidth upgrades. In general, the reliability of an opt
36、ical cable during the course of its deployment is strongly impacted by the attention paid to the reliability during the phases of work carried out before the cable is put into service. These phases can be described as follows: i) Manufactory of the optical fibres (fibre drawing and primary protectio
37、n, storage) The manufacturing phase of the fibres is critical from the point of view of reliability of the optical cable during the commercial operation. In this phase it is recommended that tests be carried out to ensure that optical and mechanical degradations will not adversely impact system perf
38、ormance during the lifetime of the cable deployment and storage. ii) Design of the optical cable structure The structural characteristics of the optical cables (fibre protection, strength member, filling materials, protections sheaths, armour, etc.) should be chosen so they will comply with the limi
39、ts stated in i) for stress and for minimum bending radius, during all the next phases. Important inputs for the definition of these characteristics are the foreseen installation method and mechanical stress (cable directly put underground, laid in ducts, laid on external poles, etc.) and, possibly,
40、also an indication of the path that the cable will follow. Finally, the choice of the characteristics of the cable should also be compliant, without degradation of the characteristics of the fibres, with the maximum temperature or humidity excursions that the cable has to face during the lifetime. i
41、ii) Insertion of the fibres in the optical cable (cabling) The cabling of the optical fibres should comply with all conditions set out in points i) and ii) iv) Design of the infrastructure for the cable laying The infrastructure for the cable laying installation should be designed and implemented in
42、 order to preserve as much as possible the cable, from external damages different from those indicated in point i). v) Laying operations Even in this phase, attention should be placed on maximum stress and minimum bending radius of the fibres in order to respect the limits mentioned in point i). G s
43、eries Supplement 59 (09/2016) 3 vi) Life of the deployed optical cable The cable faults during the lifetime of the deployed optical cables can be divided into two categories: internal faults and external faults. The internal faults (fibre breakage, increase of attenuation, etc.) are those related to
44、 the quality of the optical fibres. With the adoption of the reliability objectives pointed out in i) and ii) these internal faults should be kept to a minimum or not present at all. External faults are those caused by external elements (excavations for other services, floods, landslides, etc.). The
45、 number of this type of faults mainly depends on the quality of the protections used in the laying of the cable (depth of the excavation, dimensioning of the infrastructure of overhead lines, etc.). External faults are outside the scope of this Supplement. The main purpose of this Supplement is limi
46、ted to the study of the reliability objectives quoted in point i), i.e., the following: illustrate the processes by which the quality of the fibres degrades from the point of view of mechanical strength and from that of the increase in attenuation; list the test methods to check these degradations;
47、give the quality objectives currently adopted during the manufacturing process of the fibres. It should be clearly pointed out that in this framework the reliability objectives during the commercial life of optical cables, and the input for defining those to be considered during the production of th
48、e fibres (point i)are not specified in ITU-T. Examples of the main factors that have an impact on the choice of the reliability objectives to be considered during the commercial life of the optical cables are outlined in Appendix II. However, the more than thirty years of satisfactory operating expe
49、rience on optical cables and their wide deployment in all parts of the telecommunications networks (from the access network to intercontinental deployment) is a guarantee that the reliability objectives currently adopted in ITU-T for the production of optical fibres described in clauses 7 and 8 are suitable to ensure a very high reliability with respect to internal faults in all operating conditions. 7 Optical reliability In the 30 years of commercial optical cable depl
