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G.984.2-200303

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G.984.2-200303

    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

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

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

    COORDINATION 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 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 Digital 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 G.1000G.1999 ASPECTS

    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 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.

     ITU-T Rec. G.984.2 (03/2003) i

    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.

    ii ITU-T Rec. G.984.2 (03/2003)

    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

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

     ITU-T Rec. G.984.2 (03/2003) iii

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.

    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 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.

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

    cable.

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

    Passive Optical Networks (PON).

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

    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. 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-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 components.

    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 remotely) 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 optical 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 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

    2 ITU-T Rec. G.984.2 (03/2003)

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

    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 5 Architecture of the optical access network 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/SS/R

    ONU1

    , OOrdru

    ODNOLT

    R/S

    G.984.2_F01

    ONUn

    O, O, OOrdruldlu

    R and SReference points

    O, O, O, OOptical interfacesrdldruluRepresent 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

    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 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,

    4 ITU-T Rec. G.984.2 (03/2003)

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