Rec. ITU-T G.989.2 Amendment 1 (10/2020) 40-Gigabit-capable passive optical networks 2 (NG-PON2): Physical media dependent (PMD) layer specification Summary History FOREWORD Table of Contents 1 Scope 2 References 3 Definitions 4 Abbreviations and acronyms 5 Conventions 6 Architecture of the optical access network 6.1 Physical grouping of logical functions 6.2 ODN optical path loss (OPL) classes 6.3 Fibre distance classes 7 Services 8 User network interface and service node interface 9 Common optical network requirements 9.1 Layered structure of optical network 9.2 Wavelength plans for NG-PON2 9.3 Physical media dependent layer requirements 9.3.1 Physical media and transmission method 9.3.1.1 Transmission medium 9.3.1.2 Transmission direction 9.3.1.3 Transmission method 9.3.2 Minimum extinction ratio 9.3.3 Maximum reflectance of equipment, measured at the transmitter wavelength 9.3.4 Tolerance to reflected optical power 9.3.5 Optical path between S/R and R/S 9.3.5.1 Attenuation range 9.3.5.2 Minimum optical return loss 9.3.5.3 Maximum discrete reflectance between points S and R 9.3.5.4 Dispersion 9.3.6 Receiver at reference point R 9.3.6.1 Receiver sensitivity 9.3.6.2 Receiver overload 9.3.6.3 Maximum optical path penalty 9.3.6.4 Maximum reflectance measured at the receiver wavelength 9.3.6.5 Clock extraction capability 9.3.6.6 Consecutive identical digit immunity 9.3.6.7 Transmission quality and error performance 9.3.7 Tunable characteristics for transmitter and receiver 9.3.8 Minimum side mode suppression ratio 9.3.9 Out-of-channel power spectral density mask 10 Crosstalk-to-signal ratio tolerance for NG-PON2 10.1 Wideband X/S tolerance mask definition 10.1.1 Wideband ONU X/S tolerance 10.1.2 Wideband OLT X/S tolerance 10.2 Narrowband TWDM PON X/S tolerance mask 10.2.1 Narrowband ONU X/S tolerance mask 10.2.2 Narrowband OLT X/S tolerance mask 11 TWDM PON PMD layer requirements 11.1 PMD layer requirements 11.1.1 Nominal Line rate and clock accuracy 11.1.1.1 Downstream clock accuracy 11.1.1.2 Upstream clock accuracy 11.1.2 Line code 11.1.2.1 Downstream 11.1.2.2 Upstream 11.1.2.3 Electronic dispersion compensation 11.1.3 Operating wavelength 11.1.4 PMD parameters 11.1.4.1 Compatible optical distribution network 11.1.4.2 Optical interface parameters of downstream direction 11.1.4.3 Optical interface parameters of upstream direction 11.1.4.3.1 Example of upstream OPP and receiver substitution 11.1.4.3.2 Extinction ratio and minimum mean launch optical power trade off 11.1.5 Transmitter at reference point S 11.1.5.1 Source type 11.1.5.2 Spectral characteristics 11.1.5.2.1 Operating wavelength band 11.1.5.2.2 Nominal central frequency 11.1.5.2.3 Operating channel spacing 11.1.5.2.4 Maximum spectral excursion 11.1.5.2.5 Minimum tuning window 11.1.5.2.6 Tuning granularity 11.1.5.2.7 ONU transmitter power wavelength dependency 11.1.5.2.8 Mean launch optical power 11.1.5.2.9 Upstream optical PSD when not enabled (WNE-PSD) 11.1.5.3 Mask of transmitter eye diagram 11.1.5.3.1 OLT transmitter 11.1.5.3.2 ONU transmitter 11.1.5.3.2.1 ONU transmitter eye diagram 11.1.5.4 Jitter performance 11.1.5.4.1 Jitter transfer 11.1.5.4.2 Jitter tolerance 11.1.5.4.3 Jitter generation 11.2 Upstream physical layer overhead Annex A Tunable PtP WDM PON PMD layer requirements A.1 PMD layer requirements A.1.1 Line rate A.1.2 FEC code selection A.1.3 Line code A.1.4 Operating wavelength A.1.5 PMD parameters A.1.5.1 Compatible ODN A.1.5.2 Optical interface parameters for line rate class 1 A.1.5.3 Optical interface parameters for line rate class 2 A.1.5.4 Optical interface parameters for line rate class 3 A.1.6 Transmitter at reference point S A.1.6.1 Nominal central frequency A.1.6.2 Mask of transmitter eye diagram A.1.6.3 Jitter performance Annex B Auxiliary management and control channel B.1 Introduction B.2 Transparent AMCC B.2.1 Baseband overmodulation B.2.2 RF-pilot-tone Annex C Low loss (LL) PtP WDM PON PMD layer requirements C.1 PMD layer requirements C.1.1 ODN optical path loss classes C.1.2 Fibre distance classes C.1.3 Line rate C.1.4 FEC code selection C.1.5 Line code C.1.6 Operating wavelength C.1.7 PMD parameters C.1.7.1 Optical interface parameters for line rate class 1 C.1.7.2 Optical interface parameters for line rate class 2 C.1.7.3 Optical interface parameters for line rate class 3 C.1.8 Transmitter at reference point S C.1.8.1 Nominal central frequency C.1.8.2 Mask of transmitter eye diagram C.1.8.3 Jitter performance Annex D ONU power levelling D.1 Interaction between NG-PON2 PMD layer and TC layer D.2 Power levelling (PL) mechanism at ONU transmitter D.3 ONU autonomous power levelling D.4 OOC and OOB PSD relaxation D.5 OLT directed ONU power levelling D.6 ONU troubleshooting considerations Appendix I Wavelength considerations for NG-PON2, XG-PON1, G-PON and RF video overlay distribution services Appendix II Physical layer measurements required to support optical layer supervision Appendix III Allocation of the physical layer overhead time Appendix IV Jitter budget specifications for TWDM PON Appendix V Measurement of TWDM PON burst mode acquisition time and burst node eye opening at OLT Appendix VI Nonlinear Raman interactions in optical fibres and mitigation technologies for coexistence of multiple PONs Appendix VII Cyclic AWG channel grid design examples Appendix VIII Wavelength multiplexer, upstream inter-channel crosstalk, ONU transmitter tuning time considerations and upstream channel grid example VIII.1 Wavelength multiplexer VIII.2 Upstream inter-channel crosstalk VIII.2.1 Worst-case design approach VIII.2.2 Statistical design approach VIII.2.3 Method to limit the inter-channel crosstalk impairment VIII.3 ONU transmitter tuning time VIII.4 TWDM PON upstream channel grid examples VIII.5 Detail of OOC near the channel band edge Appendix IX Alternative line code for Raman mitigation IX.1 8B10B scheme IX.1.1 Power spectral density of 8B10B code IX.1.2 Encode and decode operations IX.1.2.1 OLT encode IX.1.2.2 ONU decode IX.1.2.3 Running disparity rules IX.1.2.4 Checking the validity of received code-groups IX.1.3 Eye mask and PMD IX.2 Miller and Miller squared scheme IX.2.1 Modified definitions for Miller code IX.2.1.1 Minimum extinction ratio IX.2.1.2 Launch optical power without input to the transmitter IX.2.2 Power spectral density of Miller code IX.2.3 Encode and decode operations IX.2.4 Eye mask IX.3 Raman mitigation suppression levels Appendix X Upstream PMD examples for TWDM PON Appendix XI Optical parameter specification for the S/R-CP reference point Bibliography