1、 International Telecommunication Union ITU-T G.979TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Optical fibre submarine cable systems Characteristics of monitoring systems for
2、optical submarine cable systems Recommendation ITU-T G.979 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 IN
3、DIVIDUAL 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 RADIOTELEPHONY AND LINE TELEPHONY G
4、.450G.499 TRANSMISSION MEDIA AND OPTICAL 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 General G.900G.909 Parameters for optical fibre cable systems G.910G.919 Digital sections at hierarchical
5、 bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.959 Digital section and digital transmission systems for custo
6、mer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979Optical line systems for local and access networks G.980G.989 Access networks G.990G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000
7、G.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.979 (10/2012) i Recommendation ITU-T G.979 Characteristics of monitoring systems for op
8、tical submarine cable systems Summary Recommendation ITU-T G.979 is concerned with the characteristics of monitoring systems for optical fibre submarine cable systems with repeaters. It covers the aspects relating to functional architecture, the characteristics of monitoring equipment and the parame
9、ters for monitoring. History Edition Recommendation Approval Study Group 1.0 ITU-T G.979 2012-10-29 15 ii Rec. ITU-T G.979 (10/2012) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication tec
10、hnologies (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 Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Tele
11、communication 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 approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some a
12、reas 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, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized o
13、perating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “s
14、hall“ 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 Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the
15、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 applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation de
16、velopment 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 implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are the
17、refore 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 means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.979 (10/2012) iii Table of Contents Page 1 Scope 1
18、 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 2 5 General architecture 2 5.1 Reference points . 4 6 Characteristics of monitoring equipment 4 6.1 Passive monitoring . 4 6.2 Active monitoring . 4 6.3 Monitoring
19、 impact 4 7 Recommended parameters for monitoring . 5 7.1 Parameters for passive monitoring . 5 7.2 Parameters for active monitoring . 5 Appendix I Examples of parameters of monitoring systems for optical submarine cable systems 6 Rec. ITU-T G.979 (10/2012) 1 Recommendation ITU-T G.979 Characteristi
20、cs of monitoring systems for optical submarine cable systems 1 Scope This Recommendation is concerned with the characteristics of monitoring systems for optical fibre submarine cable systems with repeaters. It covers the aspects relating to functional architecture, the characteristics of monitoring
21、equipment and the parameters for monitoring. The purpose of this Recommendation is to help users (e.g., submarine network operators) in their operation and maintenance, diagnostics and deployment of optical fibre submarine cable systems. Detailed information is given for: 1) monitoring system archit
22、ecture 2) reference points 3) parameters for monitoring. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provision of this Recommendation. At the time of publication, the editions indicated were valid. All Rec
23、ommendations and other references are subject 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 regular
24、ly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.972 Recommendation ITU-T G.972 (2011), Definition of terms relevant to optical fibre submarine cable systems. ITU-T G.976 Recommendation ITU-T G.9
25、76 (2010), Tests methods applicable to optical fibre submarine cable systems. ITU-T G.977 Recommendation ITU-T G.977 (2011), Characteristics of optically amplified optical fibre submarine cable systems. IEC 61746-1 IEC 61746-1 (2009), Calibration of optical time-domain reflectometers (OTDR) Part 1:
26、OTDR for single mode fibres. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 maintenance controller: See ITU-T G.972. 3.1.2 optical fibre submarine cable system: See ITU-T G.972. 3.1.3 supervisory system: See ITU-T G.972. 3.1.4 terminal
27、 station: See ITU-T G.972. 2 Rec. ITU-T G.979 (10/2012) 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 active monitoring equipment (AME): This is one of the two categories of MEs (the other is PME) which monitors the status of submerged equipment by c
28、ommunicating with the monitored equipment to obtain a performance status. 3.2.2 monitoring equipment (ME): Equipment used to monitor the status of the submerged plant of a submarine cable system, which is classified into two categories according to the monitoring mechanism: passive monitoring equipm
29、ent with no communication between the submerged plant and the monitoring equipment, or active monitoring equipment which has communication between the two. 3.2.3 passive monitoring equipment (PME): One of the two categories of MEs (the other is AME) which does not communicate with the submerged plan
30、t, but monitors the status of the submerged plant by detecting optical/electrical paths, e.g., monitoring equipment based on OTDR/COTDR. To get a performance status, return paths within submerged plant (described in clause 7.5 of ITU-T G.977) are necessary. 4 Abbreviations and acronyms This Recommen
31、dation uses the following abbreviations and acronyms: AME Active Monitoring Equipment BU Branching Unit COTDR Coherent Optical Time Domain Reflectometry CTE Cable Terminating Equipment MC Maintenance Controller ME Monitoring Equipment OTDR Optical Time Domain Reflectometry PFE Power Feeding Equipmen
32、t PME Passive Monitoring Equipment TTE Terminal Transmission Equipment Rec. ITU-T G.979 (10/2012) 3 5 General architecture CTERepeaterBUPFERepeaterCTEPFERepeaterCTEPFETTEMETTEMETTEMEFigure 1 General architecture Figure 1 shows the general architecture of an optical fibre submarine cable system with
33、monitoring equipment. Monitoring equipment should be deployed in each terminal station to provide routine monitoring for maintenance. The monitoring of system status could be obtained by periodically collecting performance data from a submerged plant. Also, for maintenance convenience, it should sup
34、port or provide interfaces to assist fault location. Two different ways may be chosen to configure an MEs connection in a submarine cable system: A TTE is connected between an ME and CTE (refer to Figure 2), and monitoring signals and service signals are coupled within the TTE and sent to the submar
35、ine cable system. An ME is connected between a TTE and CTE (refer to Figure 3), and service signals and monitoring signals are coupled within the ME and sent to the submarine cable system. NOTE 1 M denotes monitoring output interface to cables. NOTE 2 denotes the monitoring signal flow in the sendin
36、g direction; the receiving signal is obtained from the other fibre. NOTE 3 This figure defines only one terminal station in the system, the others are the same as this one. Figure 2 Monitoring output from ME 4 Rec. ITU-T G.979 (10/2012) NOTE 1 M denotes monitoring output interface to cables. NOTE 2
37、denotes the monitoring signal flow in the sending direction; the receiving signal is obtained from the other fibre. NOTE 3 This figure defines only one terminal station in the system, the others are the same as this one. Figure 3 Monitoring output from TTE As part of a supervisory system, MEs are co
38、mmonly connected to MCs through management interfaces. 5.1 Reference points With reference to Figures 2 and 3, reference points should comply with the parameters specified for monitoring. At point M, a monitoring output interface needs to comply with the following parameters: probe light output powe
39、r, wavelength, and pulse width (for passive monitoring) modulation parameters (for active monitoring). 6 Characteristics of monitoring equipment 6.1 Passive monitoring In passive monitoring, performance is obtained by detecting optical or electrical signals. Probe signals are sent to a submerged pla
40、nt, and the returned signals will be analysed to reflect the systems performance status. For example, the backscattered light of the OTDR/COTDR described in IEC 61746-1 is detected and processed, usually as curves of signal intensity versus distance to analyse and diagnose system status. One PME mon
41、itors one direction performance of the submarine cable system. To get bidirectional performance, a PME should be deployed in each terminal station. It is recommended that status changes in the probed optical paths, such as fibre breaks, variations of repeater gain, and fibre attenuation or reflectio
42、ns, are monitored in passive monitoring. As passive monitoring obtains the system status indirectly, comparison with baselines is used in status monitoring. Status monitoring should use the same parameters as the baselines to ensure the validity of the comparison and find changes in the performance
43、caused by damage or faults that alter system status. Baselines should be collected after the system has been properly deployed and should be updated after each repair or reconfiguration of the system. Rec. ITU-T G.979 (10/2012) 5 6.1.1 Fault location Fault location is often performed manually in the
44、 out-of-service state. It could be performed by a PME based on the OTDR/COTDR mechanism, or by commercial OTDR/COTDR equipment. Highly accurate resolution in fault location is always useful for maintenance. Convenient functions are recommended, for example, automatic fault location, fast fault locat
45、ion with less accuracy but a shorter time. The submerged equipment should have return paths as described in clause 7.5 of ITU-T G.977 to support OTDR/COTDR for fault location. 6.2 Active monitoring In active monitoring, the ME requests and collects directly the performance status of the submerged eq
46、uipment. Related performance parameters are input power, output power, pump current, etc. 6.3 Monitoring impact Monitoring signals may impact on the transmission performance of the monitored submarine systems. 7 Recommended parameters for monitoring Parameters for monitoring are highly implementatio
47、n-dependent, and may vary among different systems. The following is a minimum set of parameters for a users maintenance convenience. 7.1 Parameters for passive monitoring repeaters gain fibre attenuation fibre break location. 7.2 Parameters for active monitoring repeater input optical power repeater
48、 output optical power pump working current pump output power. 6 Rec. ITU-T G.979 (10/2012) Appendix I Examples of parameters of monitoring systems for optical submarine cable systems (This appendix does not form an integral part of this Recommendation.) This appendix contains examples of a PME and a
49、n AME to demonstrate the applicable parameters. Since these parameters are highly system-related, they are not specifications or requirements for MEs. It shows the cases of obtainable parameters from current technologies. Table I.1 gives information on the parameters of a PME. Table I.1 Example parameters of a PME Parameter Accuracy Note Variation of repeater gain 1.0 dB Fibre break location 1.0 km a) These parameters are applied in an OTDR/COTDR based PME. b) Values include contri
