1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.984.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2003) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Optical line systems for local and access networks Gigabit-capable Passive Opt
2、ical Networks (GPON): Physical Media Dependent (PMD) layer specification ITU-T Recommendation G.984.2 TU-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
3、CARRIER-TRANSMISSION 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 COORDINAT
4、ION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA 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
5、 systems G.910G.919 Digital sections at hierarchical 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 Digita
6、l section and digital transmission systems for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989 Access networks G.990G.999 QUALITY OF SERVICE AND PERFORMANCE - GENERIC AND USER-RELATED ASPECTS G.1000G.19
7、99 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 DIGITAL NETWORKS G.8000G.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.984.2 (03/2003) i ITU-T Recommendation G.984.2 Gigabit-capable Passive Optical Networks (GPON
8、): Physical Media Dependent (PMD) layer specification Summary This Recommendation describes a flexible optical fibre access network capable of supporting the bandwidth requirements of business and residential services, and covers systems with nominal line rates of 1244.160 Mbit/s and 2488.320 Mbit/s
9、 in the downstream direction and 155.520 Mbit/s, 622.080 Mbit/s, 1244.160 Mbit/s and 2488.320 Mbit/s in the upstream direction. Both symmetrical and asymmetrical (upstream/downstream) Gigabit-capable Passive Optical Network (GPON) systems are described. This Recommendation proposes the physical laye
10、r requirements and specifications for the Physical Media Dependent (PMD) layer. The Transmission Convergence (TC) layer and ranging protocol for GPON systems are described in a different ITU-T Recommendation. This Recommendation describes a system that represents an evolutionary development from the
11、 system described in ITU-T Rec. G.983.1. To the greatest extent possible, this Recommendation maintains the requirements of ITU-T Rec. G.983.1 to insure maximal continuity with existing systems and optical fibre infrastructure. Source ITU-T Recommendation G.984.2 was approved by ITU-T Study Group 15
12、 (2001-2004) under the ITU-T Recommendation A.8 procedure on 16 March 2003. ii ITU-T Rec. G.984.2 (03/2003) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) i
13、s 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 Telecommunication Standardization Assembly (WTSA), which meets every four years,
14、 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 areas of information technology which fall within ITU-Ts purview, the necessa
15、ry 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 operating agency. Compliance with this Recommendation is voluntary. However,
16、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 “shall“ or some other obligatory language such as “must“ and the negative equiva
17、lents 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 practice or implementation of this Recommendation may involve the use of a cla
18、imed 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 development process. As of the date of approval of this Recommendation, ITU had
19、not received notice 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 consult the TSB patent database. ITU 2003 All rights
20、reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.984.2 (03/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations 2 5 Architecture of the optical access network. 3 6 Services. 4 7 Us
21、er network interface and service node interface. 4 8 Optical network requirements. 4 8.1 Layered structure of optical network 4 8.2 Physical medium dependent layer requirements for the GPON. 4 8.3 Interaction between GPON PMD layer and TC layer 23 Appendix I Allocation of the physical layer overhead
22、 time . 25 Appendix II Description and examples of power levelling mechanism . 27 II.1 Introduction 27 II.2 ONU levels . 27 II.3 Thresholds at OLT 28 II.4 Power detection 29 ITU-T Rec. G.984.2 (03/2003) 1 ITU-T Recommendation G.984.2 Gigabit-capable Passive Optical Networks (GPON): Physical Media De
23、pendent (PMD) layer specification 1 Scope This Recommendation is intended to describe flexible access networks using optical fibre technology. The focus is primarily on a network supporting services with bandwidth requirements ranging from that of voice to Gigabit-per-second data services. Also incl
24、uded are distributive services. This Recommendation describes characteristics of the PMD layer of an Optical Access Network (OAN) with the capability of transporting various services between the user-network interface and the Service node interface. The OAN dealt within this Recommendation should en
25、able the network operator to provide a flexible upgrade to meet future customer requirements, in particular, in the area of the Optical Distribution Network (ODN). The ODN considered is based on a point-to-multipoint tree and branch option. This Recommendation concentrates on the fibre issues: the c
26、opper issues of hybrid systems are described elsewhere, e.g., xDSL Recommendations (G.99x-series). This Recommendation focuses on additions to and modifications of earlier members of the G.983.x series, which describe an architecture based on ATM over a Passive Optical Network. The purpose of the ad
27、ditions and modifications are to support higher data rates, especially for the transport of data services. This Recommendation proposes the physical layer requirements and specifications for the PMD layer of a Gigabit-capable Passive Optical Network (GPON). TC layer and ranging protocol specificatio
28、ns for GPON systems are described in a different ITU-T Recommendation. 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
29、 valid. All 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 Recommendat
30、ions is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 1 ITU-T Recommendation G.652 (2003), Characteristics of a single-mode optical fibre cable. 2 ITU-T Recommendation G.957 (1999), Optical int
31、erfaces for equipments and systems relating to the synchronous digital hierarchy. 3 ITU-T Recommendation G.982 (1996), Optical access networks to support services up to the ISDN primary rate or equivalent bit rates. 4 ITU-T Recommendation G.983.1 (1998), Broadband optical access systems based on Pas
32、sive Optical Networks (PON). 5 ITU-T Recommendation G.983.3 (2001), A broadband optical access system with increased service capability by wavelength allocation. 2 ITU-T Rec. G.984.2 (03/2003) 6 ITU-T Recommendation G.984.1 (2003), Gigabit-capable Passive Optical Networks (GPON): General characteris
33、tics. 3 Definitions This Recommendation makes frequent use of the defined terms found in ITU-T Recs G.983.1 and G.983.3. For convenience, the main definitions related to the GPON PMD layer are reported in this clause. 3.1 Optical Access Network (OAN): The set of access links sharing the same network
34、-side interfaces and supported by optical access transmission systems. The OAN may include a number of ODNs connected to the same OLT. 3.2 Optical Distribution Network (ODN): An ODN provides the optical transmission means from the OLT towards the users, and vice versa. It utilizes passive optical co
35、mponents. 3.3 Optical Line Termination (OLT): An OLT provides the network-side interface of the OAN, and is connected to one or more ODNs. 3.4 Optical Network Termination (ONT): An ONU used for FTTH and includes the User Port function. 3.5 Optical Network Unit (ONU): An ONU provides (directly or rem
36、otely) the user-side interface of the OAN, and is connected to the ODN. 3.6 Time Division Multiple Access (TDMA): Transmission technique involving the multiplexing of many time slots onto the same time payload. 3.7 Wavelength Division Multiplexing (WDM): Bidirectional multiplexing using different op
37、tical wavelength for up and downstream signals. 4 Abbreviations This Recommendation uses the following abbreviations: APD Avalanche Photodiode ATM Asynchronous Transfer Mode BER Bit Error Ratio B-ISDN Broadband Integrated Services Digital Network CID Consecutive Identical Digit DFB Distributed FeedB
38、ack laser DSL Digital Subscriber Line E/O Electrical/Optical FEC Forward Error Correction FTTH Fibre to the Home GPON Gigabit-capable Passive Optical Network ISDN Integrated Services Digital Network MLM Multi-Longitudinal Mode MPN Mode Partition Noise NRZ Non Return to Zero ITU-T Rec. G.984.2 (03/20
39、03) 3 O/E Optical/Electrical OAN Optical Access Network ODF Optical Distribution Frame ODN Optical Distribution Network OLT Optical Line Termination ONT Optical Network Termination ONU Optical Network Unit ORL Optical Return Loss PIN Photodiode without internal avalanche PON Passive Optical Network
40、PRBS Pseudo Random Bit Sequence RMS Root Mean Square SDH Synchronous Digital Hierarchy SLM Single-Longitudinal Mode SNI Service Node Interface SOA Semiconductor Optical Amplifier TC Transmission Convergence TDM Time Division Multiplexing TDMA Time Division Multiple Access UI Unit Interval UNI User N
41、etwork Interface WDM Wavelength Division Multiplexing 5 Architecture of the optical access network See ITU-T Rec. G.983.1. For convenience, Figure 5/G.983.1 is reproduced below. 4 ITU-T Rec. G.984.2 (03/2003) G.984.2_F01OLTR/S S/ROrd, OruODNR/SONUnONU1Old, OluReference pointsOptical interfacesRepres
42、ent one or more fibreRepresent optional protection fibresOrd, OruOrd, Oru, Old, OluR and SFigure 1/G.984.2 Generic physical configuration of the optical distribution network (reproduced from Figure 5/G.983.1) The two directions for optical transmission in the ODN are identified as follows: downstrea
43、m direction for signals travelling from the OLT to the ONU(s); upstream direction for signals travelling from the ONU(s) to the OLT. Transmission in downstream and upstream directions can take place on the same fibre and components (duplex/diplex working) or on separate fibres and components (simple
44、x working). 6 Services See ITU-T Rec. G.984.1 7 User network interface and service node interface See ITU-T Rec. G.984.1. 8 Optical network requirements 8.1 Layered structure of optical network See ITU-T Recs G.983.1 and G.983.3. 8.2 Physical medium dependent layer requirements for the GPON 8.2.1 Di
45、gital signal nominal bit rate The transmission line rate should be a multiple of 8 kHz. The target standardized system will have nominal line rates (downstream/upstream) of: 1244.16 Mbit/s/155.52 Mbit/s, 1244.16 Mbit/s/622.08 Mbit/s, 1244.16 Mbit/s/1244.16 Mbit/s, 2488.32 Mbit/s/155.52 Mbit/s, ITU-T
46、 Rec. G.984.2 (03/2003) 5 2488.32 Mbit/s/622.08 Mbit/s, 2488.32 Mbit/s/1244.16 Mbit/s, 2488.32 Mbit/s/2488.32 Mbit/s. Parameters to be defined are categorized by downstream and upstream, and nominal bit rate as shown in Table 1. Table 1/G.984.2 Relation between parameter categories and tables Transm
47、ission direction Nominal bit rate Table Downstream 1244.16 Mbit/s Table 2b (downstream, 1244 Mbit/s) 2488.32 Mbit/s Table 2c (downstream, 2488 Mbit/s) Upstream 155.52 Mbit/s Table 2d (upstream, 155 Mbit/s) 622.08 Mbit/s Table 2e (upstream, 622 Mbit/s) 1244.16 Mbit/s Table 2f-1 (upstream, 1244 Mbit/s
48、) Table 2f-2 (upstream, 1244 Mbit/s) 2488.32 Mbit/s Table 2g-1 (upstream, 2488 Mbit/s) Table 2g-2 (upstream, 2488 Mbit/s) All parameters are specified as follows, and shall be in accordance with Table 2a (ODN) and Tables 2b through 2g-2. These tables are generally called Table 2 in this Recommendati
49、on. There is a separate type of ONU for each combination of upstream bit-rate, downstream bit-rate, and optical path loss Class (Class A, B, or C as defined in ITU-T Rec. G.982). All parameter values specified are worst-case values, assumed to be met over the range of standard operating conditions (i.e., temperature and humidity ranges), and they include ageing effects. The parameters are specified relative to an optical section design objective of a Bit Error Ratio (BER) not worse than 1 1010for the extreme case of optical
