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 G.9807.2 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks Optical line systems for local and access networks 10 Gigabit-capable
2、 passive optical networks (XG(S)-PON): Reach extension Recommendation ITU-T G.9807.2 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-TRANSMIS
3、SION 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 RADIOTELE
4、PHONY AND LINE TELEPHONY G.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 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS
5、G.1000G.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 Metallic access networks G.9700G.9799 Optical line systems for local and access networks G.9800G.9899 In premises netw
6、orks G.9900G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.9807.2 (08/2017) i Recommendation ITU-T G.9807.2 10 Gigabit-capable passive optical networks (XG(S)-PON): Reach extension Summary Recommendation ITU-T G.9807.2 outlines the architecture and interfa
7、ce parameters for 10 gigabit-capable symmetric passive optical network (XG(S)-PON) systems with extended reach using a physical layer reach extension device, such as a regenerator or optical amplifier in the fibre link between the optical line termination (OLT) and optical network unit (ONU). Wavele
8、ngth converting, continuous mode, 1:N and combination type reach extenders (REs) are also described. The maximum reach is up to 60 km with loss budgets in excess of 28.5 dB being achievable in both spans. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.9807.2 2017-08-13 15
9、 11.1002/1000/13294 Keywords Reach extender; XG(S)-PON. * To access the 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 Rec. ITU-T G.9807.2 (08/2017) FO
10、REWORD The International Telecommunication 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 studyi
11、ng technical, operating and 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
12、 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 areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO
13、 and IEC. NOTE In this Recommendation, 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
14、 (to ensure, e.g., interoperability 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 w
15、ords does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU 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 co
16、ncerning 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 approval of this Recommendation, ITU had received notice of intellectual property, protected by pat
17、ents, which may be required 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 2017 All rights reserved. No part of this publ
18、ication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.9807.2 (08/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 4 Abbreviations and acronyms 2 5 Conventions 3 6 Optical extension schemes and architectures . 3 6.1
19、OA-based reach extenders 7 6.2 OEO-based reach extenders . 8 6.3 Hybrid architectures . 10 6.4 Wavelength conversion reach extenders 12 6.5 Wavelength re-conversion at OLT . 13 6.6 Combination G-PON and XG(S)-PON reach extenders 14 6.7 Increased fanout reach extenders 16 7 General requirements for X
20、G(S)-PON reach extenders . 17 7.1 Compatibility 17 7.2 Management . 18 7.3 Power 20 7.4 Optional enhancements 20 8 Specifications for mid-span extenders 20 8.1 Optical trunk line 20 8.2 Optical trunk line interface (R/S) and OLT interface (S/R) 21 8.3 Optical distribution network . 24 8.4 Extender i
21、nterface to optical distribution network (S/R) and ONU interface (R/S) 24 8.5 TC layer impacts . 26 8.6 WDM wavelength allocation plan for OTL . 27 Appendix I Implications on OLT receivers due to insertion of OA type extenders . 29 Appendix II Protection 31 II.1 Introduction 31 II.2 RE-independent t
22、ype B protection . 31 II.3 OEO extender-based type B protection 31 II.4 OA-extender-based type B protection architecture 32 Appendix III Optical time domain reflectometer 33 III.1 Introduction 33 III.2 Solution . 33 Appendix IV Transport of BM-to-CM converted signals over OTN . 34 Appendix V Possibl
23、e realization of OA and OEO-based extenders using wavelength conversion . 35 iv Rec. ITU-T G.9807.2 (08/2017) Page V.1 A transparent wavelength plan extender realization. 35 V.2 A conventional wavelength plan extender realization 36 V.3 An OWC based extender realization 38 Bibliography. 40 Rec. ITU-
24、T G.9807.2 (08/2017) 1 Recommendation ITU-T G.9807.2 10 Gigabit-capable passive optical networks (XG(S)-PON): Reach extension 1 Scope This Recommendation concerns 10 gigabit-capable symmetric passive optical network (XG(S)-PON) systems with optical link budgets up to the logical limits of the transm
25、ission convergence (TC) layer. It extends the capabilities of b-ITU-T G.987.4, limited to asymmetric XG-PON, to XG(S)-PON, including its dual rate working capacity. The increased optical capability, which includes both increased overall fibre length and increased overall splitting ratio, is referred
26、 to in this Recommendation as “reach extension“. The primary concerns addressed are the increase of the loss budget and the management of optical impairments. This Recommendation considers mid-span extension, which uses an active extension node placed in the middle of the optical network. The recomm
27、ended parameters for the optical distribution network(s) ODN(s) involved in this scheme are specified. Single-sided extension is considered as an improvement to the optical line terminal (OLT) interface. The systems considered here must remain compatible with existing optical network units (ONUs). F
28、urthermore, the approaches should maintain compatibility with existing OLTs to the maximum extent possible. It is recognized that some modification of the OLT equipment may be necessary, but this should be minimized. Two system architectures are considered: optical amplification and opto-electronic
29、regeneration. These can be viewed as providing reach extension at the physical layer. The key interfaces and functional blocks in each of these architectures are identified and specified. Optionally, optical-electronic-optical (OEO) type reach extender (RE) units may support a burst mode (BM) to con
30、tinuous mode (CM) conversion function, as specified in clause 6.2. In this case, it is also necessary to introduce a CM to BM conversion function before the S/R interface at the OLT. Optionally, both optical amplifier (OA) and OEO type RE units may support the wavelength conversion (WC) function, as
31、 specified in clause 6.4. In case of WC-enabled RE units, it is also necessary to introduce a WC-function block before the S/R interface. Optionally, combination RE units may support all the functions described in this Recommendation, and the G-PON RE functions described in ITU-T G.984.6. The option
32、al support of a type B protection in RE units is described. 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
33、 Recommendations 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 reg
34、ularly 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.652 Recommendation ITU-T G.652 (2016), Characteristics of a single-mode optical fibre and cable. ITU-T G.984.5 Recommendation ITU-T G.984.5 (2
35、014), Gigabit-capable passive optical networks (G-PON): Enhancement band. 2 Rec. ITU-T G.9807.2 (08/2017) ITU-T G.984.6 Recommendation ITU-T G.984.6 (2008), Gigabit-capable passive optical networks (GPON): Reach extension. ITU-T G.987.2 Recommendation ITU-T G.987.2 (2016), 10 Gigabit-capable passive
36、 optical networks (XG-PON): Physical media dependent (PMD) layer specification. ITU-T G.987.3 Recommendation ITU-T G.987.3 (2014), 10 Gigabit-capable passive optical networks (XG-PON): Transmission convergence (TC) layer specification. ITU-T G.988 Recommendation ITU-T G.988 (2012), ONU management an
37、d control interface (OMCI) specification. ITU-T G.694.1 Recommendation ITU-T G.694.1 (2012), Spectral grids for WDM applications: DWDM frequency grid. ITU-T G.694.2 Recommendation ITU-T G.694.2 (2003), Spectral grids for WDM applications: CWDM wavelength grid. ITU-T G.9807.1 Recommendation ITU-T G.9
38、807.1 (2016), 10-Gigabit-capable symmetric passive optical network (XGS-PON). ITU-T L.313 Recommendation ITU-T L.313/L.66 (2007), Optical fibre cable maintenance criteria for in-service fibre testing in access networks. 3 Definitions See clause 3 of ITU-T G.9807.1. 4 Abbreviations and acronyms See c
39、lause 4 of ITU-T G.9807.1 in addition to the following. 2R Re-amplification, Reshaping AOWC All-Optical Wavelength Converter ASE Amplified Spontaneous Emission BM Burst Mode CM Continuous Mode EONU Embedded Optical Network Unit LC Local Controller MCR Mode-Coupling Receiver OA Optical Amplifier OBF
40、Optical Bandpass Filter OEO Optical-Electronic-Optical SOA Semiconductor Optical Amplifier WC Wavelength Conversion WLCH Wavelength Channel XGM cross-Gain Modulation XGS-PON 10-Gigabit-capable Symmetric Passive Optical Network XG(S)-PON 10 Gigabit-capable (Symmetric) Passive Optical Network Rec. ITU
41、-T G.9807.2 (08/2017) 3 5 Conventions See clause 5 of ITU-T G.9807.1. 6 Optical extension schemes and architectures The basic PON architecture is shown in Figure 1. The OLT interfaces with multiple ONUs via the ODN. The OLT also provides interfaces to one or more service node interfaces (SNIs), as w
42、ell as the management system. The ONU interfaces with various UNIs. The only interfaces of interest to this Recommendation are those that face the ODN. The XGS-PON physical medium dependent (PMD) specification (see Annex B of ITU-T G.9807.1) specifies the loss profile for the ODN to be 149 dB, 1631
43、dB, 1833 dB or 2035 dB. The OLT-ODN and ONU-ODN interfaces for XGS-PON are specified in Annex B of ITU-T G.9807.1. Indeed, most ITU-compliant PONs deployed today adhere to these Recommendations. Figure 1 Basic PON architecture The architecture considered in this Recommendation is illustrated in Figu
44、re 2. A mid-span extender device is inserted between the ODN (compliant with existing PON Recommendations) and an optical trunk line (OTL), which is connected to the OLT. This architecture extends the reach of the PON by the length of the OTL, and may also increase the split ratio of the PON. Howeve
45、r, it does require electrical power for the mid-span extender. Since XG(S)-PON from the start enables the co-working of XG-PON and XGS-PON ONUs, dual rate operation for the upstream is mandatory. Figure 2 Mid-span reach extension An extended architecture considered in this Recommendation is presente
46、d in Figure 3. A WC-enabled RE-unit is inserted between the ODN (compliant with existing PON recommendations) and an optical trunk line (OTL), which is connected to the OLT. This architecture extends the reach of the PON by the length of the OTL, and may also increase the split ratio of the PON. Add
47、itionally, the WC-RE unit may aggregate several XGS-PON-class ODNs, enabled by the WDM over OTL to achieve more cost-efficient use of existing fibre infrastructure. The WC function block inserted before the S/R interface at the OLT performs adaptation between the WDM optical signals transmitted over
48、 the OTL and the OLT interfaces that are compliant with ITU-T G.9807-series Recommendations. 4 Rec. ITU-T G.9807.2 (08/2017) Figure 3 Wavelength conversion reach extender architecture An additional extended architecture considered in this architecture is shown in Figure 4. “BM-to-CM“ means burst mod
49、e to continuous mode converter, and vice versa. A BM-to-CM converter is used at the remote PON RE to convert the bursty upstream signal into a conventional continuous mode signal. A CM-to-BM converter is theoretically present at the OLT location, although it will most likely be integrated into the OLT itself. Figure 4 BM-to-CM conversion reach extender architecture An additional aspect of XG(S)-PON systems is their coexistence with the ITU-T G.9
