1、 STD-ITU-T RECMN G-b8L-ENGL L77b Li8b2571 Ob3228b 479 II INTERNATIONAL TELECOMMUNICATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.681 (I 0196) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Transmission media characteristics - Characteristics of optical c
2、omponents and sub-systems Functional characteristics of interoffice and long-haul line systems using optical amplifiers, including optical multiplexing ITU-T Recommendation G.681 (Previously CCITT Recommendation) - STDnITU-T RECMN G-bBL-ENGL 177b = 48b2571 Ob32287 305 ITU-T G-SERIES RECOMMENDATIONS
3、TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS INTERNATIONAL ANALOGUE CARRIER SYSTEM GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON ME
4、TALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY TRANSMISSION MEDIA CHARACTERISTICS SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION General Symmetric cable pairs Land coaxial cable pairs Submar
5、ine cables Optical fibre cables har onent DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUI PMENTS DIGITAL NETWORKS DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G. I OO-G. 199 G.200-G.299 G.300-G.399 G.400-G .449 G.450-G.499 G.600-G.609 G .6 1 O-G .6 1 9 G ,620-G.629 G ,630-G.649 G .650-G. 659 G.660-G.699 G.70
6、0-G.799 G.800-G.899 G.900-G.999 For further details, please refer to ITU-T List of Recommendations. - STD-ITU-T RECMN G-bL-ENGL L99b 48b257L b32288 24L ITU-T RECOMMENDATION G.681 FUNCTIONAL CHARACTERISTICS OF INTEROFFICE AND LONG-HAUL LINE SYSTEMS USING OPTICAL AMPLIFIERS, INCLUDING OPTICAL MULTIPLE
7、XING Summary This Recommendation covers the functional characteristics of interoffice and long-haul line systems using optical amplifiers, including optical multiplexing. It represents a bridge between reference/physical configurations of SDH interoffice systems described in Recommendations G.782, G
8、.783, G.958 and between functional transport network architectures described in Recommendations G.803 and G.805. Extended or new “functional blocks, functions and sub-functions“ of SDH equipment (e.g. line termination, optical/electrical/optical regenerator and optical non-regenerative repeater) are
9、 mapped on “compound functions, atomic functions and processes“ of transport networks. Optical channel layer, optical multiplex section layer and optical amplifier section layer are identified for optical transport systems. In addition optical safety considerations, including Automatic Power Shutdow
10、n (APSD) and Optical Surge Prevention (OSP), and the Optical Supervisory Channel (OSC) are topics of this Recommendation. In future Recommendations on “optical media-based transport network architectures“, there will be standardized “optical path layer with optical add and drop multiplexers and opti
11、cal cross-connects“ and “optical circuit layer with optical switches“ which are not in the scope of this Recommendation. Source ITU-T Recommendation G.681 was prepared by ITU-T Study Group 15 (1993-1996) and was approved by WTSC (Geneva, 9-18 October 1996). STD-ITU-T RECMN G-b8L-ENGL L79b q8b2571 b3
12、2287 LBB FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T is responsible for studying technical, operating and tariff q
13、uestions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Rec
14、ommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 a
15、nd IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Reco
16、mmendation may involve the use of a claimed Intellectual Property Right. The IT 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 development process. As of the date of
17、 approval of this Recommendation, the ITU hadhad not received potice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to cons
18、ult the TSB patent database. O ITU 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. 11 Recommendation G.681 (10/96) STD-ITU-T RE
19、CMN G-bBL-ENGL 1976 W 48b259L 0b32270 7TT 1 2 3 3.1 3.2 4 5 5.1 5.2 6 7 7.1 7.2 8 8.1 8.2 9 9.1 9.2 CONTENTS Page Scope 1 References 1 Terms and definitions . 2 Definitions 3 Terms defined in other Recommendations . 3 Abbreviations . 3 Applications 6 System types . 6 System components 7 7 Types of t
20、ransmission medi um . Definitions of functions and compound functions (Functional blocks) . Functions defined in other Recommendations . New functions and compound functions (Functional blocks) 7.2.1 7.2.2 7.2.3 7.2.4 7.2.5 Optical Channel Adaptation and Termination (OCNOCT) compound function Optica
21、l Supervisory Channel AdaptatiodOptical Channel Termination Optical Multiplex Section Adaptation and Termination (OMSNOMST) Optical Amplifier Section Adaptation and Termination (OASNOAST) Other functions/processes for intemetworking . (OSCNOCT) compound function compound function compound function 7
22、 7 7 8 10 10 11 13 Reference configurations for single-channel systems Functional configuration for single-channel interoffice line (IOL) systems 8.2.1 Without in-line function capabilities . 14 8.2.2 In-line non-regenerative repeater 14 8.2.3 Regenerator . 15 14 14 14 Compound functions describing
23、single-channel systems . I., . . Reference configurations for multichannel systems 17 Functional blocks describing multichannel systems 17 Functional configurations for a multichannel interoffice line system. . 17 9.2.1 Without in-line function capabilities 17 9.2.2 Non-regenerative repeater . 18 9.
24、2.3 Regenerator . 18 . . 111 Recommendation G.681 (10/96) STD-ITU-T RECMN G-b1-ENGL 177b = 4b2571 Ob32291 3b 9 9.3 Intenvorking of compound functions in a multichannel system 1 O Optical safety considerations (Optical surge prevention. automatic power shutdown) Annex A . Relation between compound fu
25、nctions and layered transport network architecture . Annex B . Mapping between compound functions and transport functions . Appendix I . Physical implementations of multichannel systems Transponder implementations Stand-alone Booster Amplifier (BA) and Pre-Amplifier (PA) . I . 1 1.2 Appendix II . Re
26、alizations of new functions 11.1 11.2 Optical Amplification (OA) function . Dispersion Accommodation (DA) function . Appendix III . Example of functional modelling for single-channel and multichannel III . 1 111.2 systems . Example 1 : Stand-alone equipment Example 2: Mapping of functional blocks of
27、 a line terminal in a single-channel system on OAT and OAR implementations . Page 19 24 25 26 26 28 29 29 30 30 30 30 21 iv Recommendation G.681 (10/96) STD-ITU-T RECMN G-bAl-ENGL 199b D VBb259L Ob32292 772 Recommendation 6.681 FUNCTIONAL CHARACTERISTICS OF INTEROFFICE AND LONG-HAUL LINE SYSTEMS USI
28、NG OPTICAL AMPLIFIERS, INCLUDING OPTICAL MULTIPLEXING (Geneva 1996) 1 Scope This Recommendation applies to the functional characteristics of interoffice and long-haul line systems using Optical Amplifiers (OAs), including optical multiplexing. Existing Recommendations such as G.958, and the G.780-Se
29、ries have not considered these new technologies. As such this Recommendation is the first attempt to characterize the functions that OAs and optical multiplexing require to describe these capabilities. Its present structure and contents describe the systems where optical interfaces for single-channe
30、l systems with optical amplifiers and optical interfaces for multichannel systems with optical amplifiers are implemented. This Recommendation represents a bridge between reference/physical configurations of SDH interoffice systems in Recommendations G.782, G.783, G.958 and between functional networ
31、k architectures described in Recommendations G.803 and G.805. Thus, it is structured in a way that is intended to complement the directions that the network architecture and the network management activities are following. The guiding principles of these areas have been used in developing this descr
32、iption. The description is based on a cliendserver approach. In order to provide this, the functional blocks described in this Recommendation were derived from rules developed from layered transport architecture techniques. The functions related to management were developed from an understanding of
33、information flows. It is not in the scope of this Recommendation to identifj how the management messages are formatted or the protocols by which they are conveyed. The line systems described within this Recommendation are intended to provide transverse compatibility, i.e. the possibility of mixing v
34、arious manufacturers equipments within a particular system. The use of optical transmission capabilities including optical multiplexing and amplification requires management solutions. This Recommendation describes how a supervisory signal is combined with user information. NOTE - This Recommendatio
35、n has been prepared from the experience with Erbium-doped silica-based fibre amplifiers (EDFA), operating in the 1550 nm wavelength region. Future optical amplifiers (e.g. semi- conductor optical amplifiers or optical amplifiers based on different active fibres, possibly in the 13 10 nm wavelength r
36、egion) are not intended to be excluded from this Recommendation and may lead to additional functions, as well as to modifications of the existing ones. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provision
37、s of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; all users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendatio
38、ns and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. Recommendation G.681 (10196) 1 STD-ITU-T RECMN GmbBL-ENGL L99b = 48b2591 b32273 b07 M ITU-Recommendation G.652 (1993), Characteristics of a single-mode optical$bre cable. ITU-Recommendat
39、ion G.653 (1 993), Characteristics of a dispersion-shifted single-mode opticaljbre cable. ITU-Recommendation G.655 (1 996), Characteristics of a non-zero dispersion single-mode opticaljbre cable. ITU-Recommendation G.661 (1 996), Definition and test methods for the relevant generic parameters of opt
40、ical jbre ampliJiers. ITU-Recommendation G.662 (1 995), Generic characteristics of optical jbre ampliJier devices and sub-systems. ITU-Recommendation G.663 (1 996), Application related aspects of optical fibre ampliJier devices and sub-systems. ITU-Recommendation G.671 (1 996), Transmission characte
41、ristics of passive optical components. ITU-Recommendation G.707 (1 996), Network node interface for the Synchronous Digital Hierarchy (SDH). ITU-Recommendation G.78 1 (1 994), Structure of Recommendations on equipment for the Synchronous Digital Hierarchy (SDH), ITU-Recommendation G.782 (1 994), Typ
42、es and general characteristics of Synchronous Digital Hierarchy (SOH) equipment. ITU-Recommendation G.783 (19941, Characteristics of Synchronous Digital Hierarchy (SDH) equipment functional blocks. ITU-Recommendation G.784 (1 994), Synchronous Digital Hierarchy (SDH) management. ITU-Recommendation G
43、.803 (1 993), Architectures of transport networks based on the Synchronous Digital Hierarchy (SDH) . ITU-Recommendation G.805 (1 995), Generic functional architecture of transport network.;. ITU-Recommendation G.825 (1993), The control of jitter and wander within digital networh which are based on t
44、he Synchronous Digital Hierarchy (SOH). ITU-Recommendation G.957 (1 995), Optical interfaces for equipments and systems relating to the synchronous digital hierarchy. ITU-Recommendation G.958 (1 994), Digital line systems based on the synchronous digital hierarchy for use on optical fibre cables. IE
45、C 825-1 11993, Safety of laser products - Part 1: Equipment classijkation, requirements and users guide. IEC 825-211993, Safety of laser products - Part 2: Safety of optical Jibre communication systems. Terms and definitions This Recommendation defines the following terms. 2 Recommendation G.681 (10
46、96) STD-ITU-T RECMN GSbBL-ENGL L99b 48b259L b3229LI 545 3.1 Definitions 3.1.1 optical amplifier: The optical amplifier is an element that alters the amplitude of the incident signals but does not perform timing recovery or decision thresholding. Many optical signals can be accommodated simultaneousl
47、y. It can communicate to the system management facility using a data messaging channel, which may be of optical and electrical means. The optical supervisory signal is for monitoring in-line optical amplifiers. The electrical supervisory signal approach is used in systems without in-line amplifiers.
48、 3.1.2 wavelength: Whilst wavelength is used throughout this Recommendation, it is recognized that future multichannel systems will be defined in frequency spacing. Wavelength and frequency are interchangeable for the purposes of this Recommendation. 3.1.3 optical channel: The optical channel in an
49、optical interoffice link or regenerator section starts at the access point, AP, of an OCNOCT in a line termination (or regenerator) and ends at the access point, AP, of an OCAIOCT in a line termination (or regenerator). 3.1.4 compound function: The compound function contains a number of atomic functions in a single layer. 3.1.5 atomic function: The atomic function is a function, which, if divided into simpler functions would no longer be uniquely defined for transmission hierarchies. It is therefore indivisible from a network point of view. Atomic functions are compos
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