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ITU T-REC-G.984.2-200303

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ITU T-REC-G.984.2

INTERNATIONAL TELECOMMUNICATION UNION

ITU-T G.984.2

    (03/2003) TELECOMMUNICATION

    STANDARDIZATION SECTOR

    OF ITU

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 Optical 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 CARRIER- G.200G.299

    TRANSMISSION SYSTEMS

    G.300G.399 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES

    G.400G.449 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES

    G.450G.499 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY

    G.500G.599 TESTING EQUIPMENTS

    G.600G.699 TRANSMISSION MEDIA CHARACTERISTICS

    G.700G.799 DIGITAL TERMINAL EQUIPMENTS

    G.800G.899 DIGITAL NETWORKS

    G.900G.999 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM

    G.900G.909 General

    G.910G.919 Parameters for optical fibre cable systems

    G.920G.929 Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s

    G.930G.939 Digital line transmission systems on cable at non-hierarchical bit rates

    G.940G.949 Digital line systems provided by FDM transmission bearers

    G.950G.959 Digital line systems

    G.960G.969 Digital section and digital transmission systems for customer access to ISDN

    G.970G.979 Optical fibre submarine cable systems

    G.980G.989 Optical line systems for local and access networks

    G.990G.999 Access networks

    G.1000G.1999 QUALITY OF SERVICE AND PERFORMANCE - GENERIC AND USER-RELATED

     ASPECTS

    G.6000G.6999 TRANSMISSION MEDIA CHARACTERISTICS

    G.7000G.7999 DIGITAL TERMINAL EQUIPMENTS

    G.8000G.8999DIGITAL NETWORKS

     For further details, please refer to the list of ITU-T Recommendations.

ITU-T Recommendation G.984.2

    Gigabit-capable Passive Optical Networks (GPON):

    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 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 layer 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 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 (2001-2004) under the ITU-T Recommendation A.8 procedure on 16 March 2003.

    i 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) 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 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 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-T's 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 operating 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 "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 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 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 development 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, 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 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)ii

    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 User 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 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

    29II.4 Power detection ..............................................................................................

    ITU-T Rec. G.984.2 (03/2003) iii

null

ITU-T Recommendation G.984.2

    Gigabit-capable Passive Optical Networks (GPON):

    Physical Media Dependent (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 included 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 enable 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 copper 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 additions 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 specifications for GPON systems are described in a different ITU-T Recommendation.

    References 2

    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 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 regularly 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 Recommendation G.652 (2003), Characteristics of a single-mode optical fibre [1]

    cable.

    ITU-T Recommendation G.957 (1999), Optical interfaces for equipments and systems [2]

    relating to the synchronous digital hierarchy.

    ITU-T Recommendation G.982 (1996), Optical access networks to support services up to [3]

    the ISDN primary rate or equivalent bit rates.

    ITU-T Recommendation G.983.1 (1998), Broadband optical access systems based on [4]

    Passive Optical Networks (PON).

    ITU-T Recommendation G.983.3 (2001), A broadband optical access system with [5]

    increased service capability by wavelength allocation.

    ITU-T Rec. G.984.2 (03/2003)1

[6] ITU-T Recommendation G.984.1 (2003), Gigabit-capable Passive Optical

    Networks (GPON): General characteristics.

    Definitions 3

    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.

    Optical Access Network (OAN): The set of access links sharing the same network-side 3.1

    interfaces and supported by optical access transmission systems. The OAN may include a number

    of ODNs connected to the same OLT.

    Optical Distribution Network (ODN): An ODN provides the optical transmission means 3.2

    from the OLT towards the users, and vice versa. It utilizes passive optical components.

    Optical Line Termination (OLT): An OLT provides the network-side interface of the 3.3

    OAN, and is connected to one or more ODNs.

    Optical Network Termination (ONT): An ONU used for FTTH and includes the User 3.4

    Port function.

    Optical Network Unit (ONU): An ONU provides (directly or remotely) the user-side 3.5

    interface of the OAN, and is connected to the ODN.

    Time Division Multiple Access (TDMA): Transmission technique involving the 3.6

    multiplexing of many time slots onto the same time payload.

    Wavelength Division Multiplexing (WDM): Bidirectional multiplexing using different 3.7

    optical wavelength for up and downstream signals.

    Abbreviations 4

    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 FeedBack 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 (03/2003)2

    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

     Photodiode without internal avalanche PIN

    Passive Optical Network PON

    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 Network Interface WDM Wavelength Division Multiplexing

    Architecture of the optical access network 5

    See ITU-T Rec. G.983.1. For convenience, Figure 5/G.983.1 is reproduced below.

    ITU-T Rec. G.984.2 (03/2003)3

     R/S S/R ONU1

    Ord, Oru

    ODN OLT

    R/S

    G.984.2_F01

    ONUn

     Ord, Oru Old, Olu

    R and S Reference points

    Ord, Oru, Old, Olu Optical interfaces Represent one or more fibre Represent optional protection fibres

    Figure 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:

    downstream 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 (simplex working).

6 Services

    See ITU-T Rec. G.984.1

    User network interface and service node interface 7

    See ITU-T Rec. G.984.1.

    Optical network requirements 8

    Layered structure of optical network 8.1

    See ITU-T Recs G.983.1 and G.983.3.

    Physical medium dependent layer requirements for the GPON 8.2

    8.2.1 Digital 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 Rec. G.984.2 (03/2003)4

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