ITU-T SG15-Q5

1. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 Characteristics and test methods of optical fibres and cables

2. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 • Optical fibre cables have been specified and deployed in telecommunication networks worldwide, finding wide application in local access networks, interoffice and long distance networks, and submarine networks. • New optical fibre technologies and new applications continue to drive the need for additional specifications. For example, the growing demand for broadband services (multimedia, high-speed internet, HDTV, etc.) to and in buildings and homes requires the introduction of high-capacity transmission media into the local networks. • Moreover, the widespread deployment of broadband services requires a new class of optical fibre that can substantially expand the transmission capacity of a traditional single-mode fibre.

3. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 The responsibility under this Question : • The description and testing of basic single-mode and multimode fibre types, with parameter tables describing the variations within each of the basic types. • Definitions of attributes and associated test methods for geometrical, transmission, mechanical and reliability characteristics. • Descriptions of different possible fibre solutions for local access networks. • Descriptions of relationships between the different attributes with other attributes and with variations in the environment. • The following major Recommendations, in force at the time of approval of this Question, fall under its responsibility: G.650-series, G.651.1, G.652, G.653, G.654, G.655, G.656, G.657. The following Supplement also falls under its responsibility: G.Sup40, G.Sup.47.

4. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 • Question: • Support bit-rates up to and above 100 Gbit/s with time-division multiplexing (TDM)? • Open new spectral transmission regions as the passband of optical amplifiers increases and as the number of wavelength-division multiplexed channels increases? • Support Dense Wavelength Division Multiplexing (DWDM) applications in access, metropolitan, long distance and submarine networks? • Support Coarse Wavelength Division Multiplexing (CWDM) applications across the full spectrum mainly in access and metropolitan networks? • Support parallel space division multiplexing applications? • Support space- and/or mode-division multiplexing applications? • Improve the nonlinear optical performance limits optical fibres for high bit rate transmission beyond 100 Gbit/s

5. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 • What is needed to provide cost-effective optical access networks to and in buildings and homes? • How can cohesive Recommendations on the optical access network cabling be formulated? These could be divided by the main types of topology and could include aspects such as: • Optical fibre • Cable constructions • Installation techniques impact on fibre characteristics • Impact of hardware, such as splicing trays, customer outlet …, on fibre characteristics  • Hardware • Reliability • Testing and maintenance • NOTE: Some of these aspects are, at present, covered also in Q16/15 so coordination is necessary.

6. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 • Study items to be considered include: • Geometrical, mechanical, and optical properties of the glass and coating, for single-mode fibre applications. • Reliability of fibres and cables (lifetime and failure rate) under a wide variety of temperature and humidity environments; long-term aging. • Definition, modeling, and measurements of Polarization Mode Dispersion (PMD) relationships with chromatic dispersion, polarization dependent loss (PDL), and with time and temperature. • Possible additional fibre types, and additional parameter tables within the existing Recommendations. • Other types of traditional single-mode silica fibres optimized for higher bitrates (e.g. above 100 Gbit/s) DWDM systems.

7. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 • Other types of traditional single-mode silica fibres for opening new spectral transmission regions (as the pass-band of optical amplifiers increases. • Other types of traditional single-mode silica fibres for reducing non-linearity effects (as the channel spacing becomes smaller). • Optical fibres made by materials different from silica (e.g. fluoride fibres, chalcogenidefibres, polycrystalline fibres, plastic, etc.). • Length uniformity of fibre geometrical and transmission characteristics that have a functional impact on systems, and are not merely a quality control issue. • Dispersion management of high-performance systems. • Fibre damage from high power and small bend radii.

8. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 • Fibre and cable, requirements for parallel transmissions on either CWDM or Space division multiplexing on single-mode or multimode fibres at above 100 Gbit/s. • Fibre and cable, requirements for space- and/or mode-division multiplexing on single-mode or few-mode fibres at above 100 Tbit/s/fibre. • In-home and in-building optical network beyond the network termination point, taking into account the strong relationship between fibre, cable, connection hardware, network topology and operating speeds, and installation techniques. Strategies for mixed transmission media such as hybrid fibre/coax. • Define a “degree of compatibility” between the different types of fibres installed in the same link in order to estimate the transmission characteristics in terms of expected loss (e.g. define the expected limits of splice loss, connectors loss…), chromatic dispersion, PMD….. • Define fibre parameters in the monitoring wavelength region (up to 1650 nm).

9. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 Tasks Tasks include, but are not limited to: • Modify parameters in Recommendations G.651.1, G.652, G.653, G.654, G.655, G.656, and G.657. • Update the text of G.Sup40 and G.Sup.47, as required. • Develop new Recommendations or parameter tables within existing Recommendations for possible additional fibre types. • Develop definitions of new parameters, and corresponding factory and field test methods, RTMs and ATMs, for G.650.1, G.650.2, and G.650.3. • Develop guidelines for users of optical fibres and cables. • Develop cohesive Recommendations on the cabling of optical access networks to and in buildings and homes.

10. عليرضا ربيعي سرپرست گروه مطالعاتي 15 ITU-T SG15-Q5 Relationships • Recommendations: • G.65x- and G.95x- and L-series Recommendations • Questions: • Q1/15, Q2/15, Q5/15, Q6/15, Q7/15, Q8/15, Q16/15, Q17/15 • Standardization bodies, forums and consortia:

11. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.651.1 • Characteristics of a 50/125 μm multimodegraded index optical fibre cable for the opticalaccess network • Summary • ITU-T Recommendation G.651.1 recommends a quartz multimode fibre to be used for the accessnetwork in specific environments. These environments are multi-tenant building sub-networks inwhich broadband services have to be delivered to individual apartments. • The recommendedmultimode fibre supports the cost-effective use of 1 Gbit/s Ethernet systems over link lengths up to550 m, usually based upon the use of 850 nm transceivers. • The recommended fibre type is an improved version of the well-known 50/125 μm multimodegraded-index fibre as recommended in ITU-T Recommendation G.651. Its cost effective use is verycommon in datacom systems applied in enterprise buildings throughout the world for quite a number of years.

12. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.651.1 Contents : -Scope References -Terms and definitions -Abbreviations and acronyms -Fibre attributes -Cladding diameter -Core diameter

13. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.651.1 -Core concentricity error - Non-circularity -Numerical aperture -Macrobending loss - Material properties of the fibre -Refractive index profile - Modal bandwidth -Chromatic dispersion coefficient Cable attributes - Attenuation coefficient Modal bandwidth -Tables of recommended values

14. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652 • Characteristics of a single-mode optical fibre and cable Summary: • Recommendation ITU-T G.652 describes the geometrical, mechanical and transmission attributes of a single‑mode optical fibre and cable which has zero-dispersion wavelength around 1310 nm. • The ITU‑T G.652 fibre was originally optimized for use in the 1310 nm wavelength region, but can also be used in the 1550 nm region. This is the latest revision of a Recommendation that was first created in 1984 and deals with some relatively minor modifications. This revision is intended to maintain the continuing commercial success of this fibre in the evolving world of high-performance optical transmission systems. • Table 1 "G.652.A attributes" and Table 3 "G.652.C attributes" of the 2009 edition have not been changed and are not incorporated in this 2016 edition. These tables are still available in the 2009 edition of ITU-T G.652 Recommendation. These optical fibres and cables can be used for systems with less stringent PMD requirements (e.g. systems with short link lengths or those with high PMD tolerance). • Table 2 “G.652.B attributes” and Table 4 “G.652.D attributes” of the 2009 edition have been maintained with revisions in this 2016 edition, renumbered to Table 1 “G.652.B attributes” and Table 2 “G.652.D attributes”.

15. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652 • Contents • Fibre attributes • Mode field diameter • Cladding diameter • Core concentricity error • Non-circularity • Cut-off wavelength • Macrobending loss • Material properties of the fibre • Refractive index profile • Longitudinal uniformity of chromatic dispersion • Chromatic dispersion

16. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652 Cableattributes: Attenuation coefficient Polarizationmode dispersion coefficient Tables of recommended values: Appendix I Information about cabled fibre link attributes used for system design Attenuation Chromatic dispersion Differential group delay (DGD) Tables of common typical values Non-linear coefficient

17. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652 • Appendix II : Information on data collection of G.652.D fibre maximum / minimum chromatic dispersion for boundary line specification

18. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652 Scope • This Recommendation describes a single‑mode optical fibre and cable which has zero‑dispersion wavelength around 1310 nm and can be used in the 1310 nm and 1550 nm regions. Both analogue and digital transmission can be used with this fibre. • The geometrical, optical, transmission and mechanical parameters are described below in three categories of attributes: fibre attributes are those attributes that are retained throughout cabling and installation ; cable attributes that are recommended for cables as they are delivered;link attributes that are characteristic of concatenated cables, describing estimation methods of system interface parameters based on measurements, modelling or other considerations. Information for link attributes and system design are in Appendix I.

19. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652

20. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.652 • NOTE – Depending on the length of the links, dispersion accommodation can be necessary for some [b-ITU T G.691], [b-ITU-T G.692] or [b-ITU-T G.959.1] application codes. • The meaning of the terms used in this Recommendation and the guidelines to be followed in the measurement to verify the various characteristics are given in [ITU-T G.650.1] and [ITU T G.650.2]. • The characteristics of this fibre, including the definitions of the relevant parameters, their test methods and relevant values, will be refined as studies and experience progress.

21. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.653 • Characteristics of a dispersion-shifted,single-mode optical fibre and cable Summary: • Recommendation ITU-T G.653 describes the geometrical, mechanical and transmission attributes of a single-mode optical fibre and cable with zero-dispersion wavelength shifted into the 1550 nm wavelength region. • This is the latest revision of the Recommendation that was first created in 1988. • This revision removes jumper cable cut-off wavelength definition and adds Notes allowing higher maximum cabled attenuation for short jumper cables.

22. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.653 Fibre attributes : • Mode field diameter • Cladding diameter • Core concentricity error • Non-circularity • Cut-off wavelength • Macrobending loss • Material properties of the fibre • Refractive index profile • Longitudinal uniformity of chromatic dispersion • Chromatic dispersion coefficient

23. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.653 Cable attributes • Attenuation coefficient • Polarization mode dispersion coefficient (PMD) Tables of recommended values • Appendix I – Information for link attribute and system design • Attenuation • Chromatic dispersion • Differential group delay (DGD) • Non-linear coefficient • Table of common typical values • Chromatic dispersion coefficient limits for Table 2

24. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.653 Scope • This Recommendation describes a dispersion-shifted, single-mode optical fibre and cable which has a nominal zero-dispersion wavelength close to 1550 nm, and a dispersion coefficient which is monotonically increasing with wavelength. • This fibre is optimized for use in the 1550 nm region, but may also be used at around 1310 nm subject to the constraints outlined in this Recommendation. • Some provisions are made to support transmission at higher wavelengths up to 1625 nm and lower wavelengths down to 1460 nm. • Chromatic dispersion coefficient values at these wavelengths may be specified to support coarse wavelength division multiplexing (CWDM) systems that do not have significant impairment due to non-linear effects.

25. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.653 • The geometrical, optical, transmission and mechanical parameters are described below in three categories of attributes: – fibre attributes are those attributes that are retained throughout cabling and installation; – cable attributes that are recommended for cables as they are delivered; – link attributes that are characteristics of concatenated cables, describing estimation method of system interface parameters based on measurements, modelling, or other considerations. -Information for link attribute and system design are in Appendix I.

26. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.654 Characteristics of a cut-off shifted single-mode optical fibre and cable Summary • Recommendation ITU-T G.654 describes the geometrical, mechanical and transmission attributes of a single-mode optical fibre and cable which has the zero-dispersion wavelength around 1300 nm wavelength, and which is loss-minimized and cut-off wavelength shifted at around the 1550 nm wavelength region. • This is the latest revision of this Recommendation that was first created in 1988. • Version 10.0 introduces category E ITU-T G.654 fibre in order to significantly improve the optical signal to noise ratio (OSNR) characteristics to support 100Gbit/s and beyond 100Gbit/s digital coherent transmission systems in terrestrial deployments. • It is intended to maintain the continuing commercial success of this fibre in the evolving world of high-performance optical transmission systems.

27. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.654 Contents Fibre attributes : • Mode field diameter • Cladding diameter • Core concentricity error • Non-circularity • Cut-off wavelength • Macrobending loss • Material properties of the fibre • Refractive index profile • Longitudinal uniformity of chromatic dispersion • Chromatic dispersion coefficient

28. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.654 Cable attributes • Attenuation coefficient • Polarization mode dispersion coefficient (PMD) Tables of recommended values • Appendix I – Information for link attribute and system design • Attenuation • Chromatic dispersion • Differential group delay (DGD) • Non-linear coefficient • Table of common typical values • Chromatic dispersion coefficient limits for Table 2

29. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.654 scope • This Recommendation describes a single-mode optical fibre and cable which has the zero dispersion wavelength around 1300 nm wavelength, which is loss-minimized and cut-off shifted at a wavelength around 1550 nm, and which is optimized for use in the 1530-1625 nm region. • This very low loss cut-off shifted fibre (CSF) can be used for long-distance digital transmission applications such as long-haul terrestrial line systems and submarine cable systems using optical amplifiers. • The geometrical, optical (attenuation, cut-off wavelength, chromatic dispersion and polarization mode dispersion, etc.), transmission and mechanical characteristics of this CSF are described below.

30. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.654 • Some provisions are made to support transmission at higher wavelengths up to 1625 nm. • The geometrical, optical, transmission and mechanical parameters are described below in three categories of attributes: fibre attributes are those attributes that are retained throughout cabling and installation; • cable attributes that are recommended for cables as they are delivered; link attributes that are characteristics of concatenated cables, describing estimation methods of system interface parameters based on measurements, modelling, or other considerations. • Information for link attributes and system design are given in Appendix I.

31. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.654 • This Recommendation, and the different performance categories found in the tables of clause 8, are intended to support the following related-system Recommendations: • [b-ITU-T G.696.1]; • [b-ITU-T G.957]. • The meaning of the terms used in this Recommendation, and the guidelines to be followed in the measurements to verify the various characteristics, are given in [ITU-T G.650.1] and [ITU T G.650.2]. • The characteristics of this fibre, including the definitions of the relevant parameters, their test methods and relevant values, will be refined as studies and experience progress.

32. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.655 Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable Summary • This Recommendation describes the geometrical, mechanical, and transmission attributes of a single-mode optical fibre which has the absolute value of the chromatic dispersion coefficient greater than some non-zero value throughout the wavelength range from 1530 nm to 1565 nm. • This dispersion reduces the growth of non-linear effects which are particularly deleterious in dense wavelength division multiplexing systems. • The last revision in 2006 adds two new categories of this fibre in Tables D and E. Both of these categories limit the chromatic dispersion coefficient by a pair of bounding curves versus wavelength for the range of 1460 nm to 1625 nm.

33. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.655 • Although the dispersion can change sign at wavelengths less than 1530 nm, the inclusion of these lower wavelengths is intended to provide information to support coarse wavelength division multiplexing applications which do not have significant non-linear impairments, at channels from 1471 nm and higher. • Thesetables are introduced to distinguish the two main families of ITU-T G.655 fibres that are supported by multiple vendors. • Table 1, "G.655.A attributes", Table 2, "G.655.B attributes", and Table 3, "G.655.C attributes", of the 2003 edition have not been changed, of which, only the G.655.C attributes table is included in this current edition.

34. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.655 • This is the latest revision of a Recommendation that was first created in 1996. • This revision adds a new note in the G.655.C, G.655.D and G.655.E attributes tables, allowing higher maximum cabled attenuation for short cables. • Jumper cable cut-off wavelength is deleted a well. • This revision is expected to improve harmonization with IEC standards.

35. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.655 Contents Fibre attributes : • Mode field diameter • Cladding diameter • Core concentricity error • Non-circularity • Cut-off wavelength • Macrobending loss • Material properties of the fibre • Refractive index profile • Longitudinal uniformity of chromatic dispersion • Chromatic dispersion coefficient

36. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.655 Cable attributes • Attenuation coefficient • Polarization mode dispersion coefficient (PMD) Tables of recommended values • Appendix I – Information for link attribute and system design • Attenuation • Chromatic dispersion • Differential group delay (DGD) • Non-linear coefficient • Table of common typical values • Chromatic dispersion coefficient limits for Table 2

37. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.656 Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport Summary • Recommendation ITU-T G.656 describes the geometrical, mechanical, and transmission attributes ofa single-mode optical fibre which has the positive value of the chromatic dispersion coefficientgreater than some non-zero value throughout the wavelength range of anticipated use 1460-1625 nm. • This dispersion reduces the growth of non-linear effects which are particularly deleterious in densewavelength division multiplexing systems.

38. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.656 • This fibre can be used for both CWDM (coarse wavelength division multiplexing) and DWDM(dense wavelength division multiplexing) systems throughout the wavelength region between 1460and 1625 nm. • Edition 2 limits the chromatic dispersion coefficient by a pair of bounding curves vs wavelength forthe range of 1460 nm to 1625 nm, which provides information to support CWDM and DWDMapplications. • Edition 3 removes jumper cut-off wavelength

39. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.656 Contents Fibre attributes : • Mode field diameter • Cladding diameter • Core concentricity error • Non-circularity • Cut-off wavelength • Macrobending loss • Material properties of the fibre • Refractive index profile • Longitudinal uniformity of chromatic dispersion • Chromatic dispersion coefficient

40. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.656 Cable attributes • Attenuation coefficient • Polarization mode dispersion coefficient (PMD) Tables of recommended values • Appendix I – Information for link attribute and system design • Attenuation • Chromatic dispersion • Differential group delay (DGD) • Non-linear coefficient • Table of common typical values • Chromatic dispersion coefficient limits for Table 2

41. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 • Characteristics of a bending-loss insensitive single-mode optical fibre and cable • Summary • Worldwide, technologies for general transport network and broadband access networks are advancing rapidly. Among these, the technology applying single-mode fibre provides for a high-capacity transmission medium which can answer the growing demand for high speed and broadband services. • The experience with the installation and operation of single-mode fibre and cable-based networks is huge, and [ITU-T G.652] which describes its characteristics has been adapted to this experience. Nevertheless, the specific use in an optical access network puts different demands on the fibre and cable which impacts its optimal performance characteristics. • Differences with respect to the use in the general transport network are mainly due to the high density network of distribution and drop cables in the access network.

42. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 • The limited space and the many manipulations ask for operator-friendly fibre performance and low bending sensitivity. In addition, the cabling in the crowded telecom offices where space is a limiting factor has to be improved accordingly. • Yet, certain areas of the general transport network can also be described as space limited, where bend optimized cabling can be advantageous. • It is the aim of Recommendation ITU-T G.657 to support this optimization by recommending strongly improved bending performance compared with the existing ITU-T G.652 single-mode fibre and cables. • This is done by means of two categories of single-mode fibres, one of which, category A, is fully compliant with the ITU-T G.652 single-mode fibres and can be deployed throughout the general transport network as well as the access network.

43. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 • The other, category B, is not necessarily compliant with [ITU T G.652] but is capable of low values of macrobending losses at very low bend radii and is intended for application in the access network inside buildings or near buildings (e.g., outside building riser cabling). • These category B fibres are system compatible with ITU-T G.657.A (and ITU-T G.652.D) fibres in access networks. • This fourth edition of Recommendation ITU-T G.657 includes some modifications, amongst others the usage of category A fibres for all applications (access networks as well as general transport networks) where ITU-T G.652.D fibres are used, now with bending improved characteristics.

44. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 Contents Fibre attributes : • Mode field diameter • Cladding diameter • Core concentricity error • Non-circularity • Cut-off wavelength • Macrobending loss • Material properties of the fibre • Refractive index profile • Longitudinal uniformity of chromatic dispersion • Chromatic dispersion coefficient

45. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 Cable attributes • Attenuation coefficient • Polarization mode dispersion coefficient (PMD) Tables of recommended values

46. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 Scope • This Recommendation describes two categories of single-mode optical fibre cable with improved bending loss performance compared with that of ITU-T G.652 fibres. ITU-T G.657 fibre was originally developed for use in access networks, including inside buildings at the end of these networks. Both categories A and B contain two subcategories which differ in macrobending loss. • Category A fibres are optimized for reduced macrobending loss compared to ITU-T G.652.D fibres and can be deployed throughout the access network. These fibres are suitable to be used in the O, E, S, C and L-band (i.e., throughout the 1260 nm to 1625 nm range). • Fibres and requirements in this category are a subset of ITU-T G.652.D and therefore compliant with ITU-T G.652.D fibres and have the same transmission and interconnection properties. • Thus, ITU-T G.657.A fibres can be used for all networks where ITU-T G.652.D fibres are specified.

47. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 • Subcategory ITU-T G.657.A1 fibres are appropriate for a minimum design radius of 10 mm. • Subcategory ITU-T G.657.A2 fibres are appropriate for a minimum design radius of 7.5 mm. • Category B fibres are optimized for further reduced macrobending loss and therefore are capable of being used at very low values of bend radius. These fibres are intended for short reach distances (less than 1000 m) at the end of access networks, in particular inside buildings or near buildings (e.g., outside building riser cabling). The application length of ITU-T G.657.B fibre depends on the deployment strategy of each network operator. These fibres are suitable for use in the O, E, S, C and L-band (i.e., throughout the 1260 nm to 1625 nm range). • Category B fibres are not necessarily compliant with ITU T G.652.D in terms of chromatic dispersion coefficient and PMD specifications. These fibres however, are system compatible with ITU-T G.657.A (and ITU-T G.652.D) fibres in access networks. • Subcategory ITU-T G.657.B2 fibres are appropriate for a minimum design radius of 7.5 mm. • Subcategory ITU-T G.657.B3 fibres are appropriate for a minimum design radius of 5 mm.

48. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 • This Recommendation and the different performance categories found in the tables of clause 8 are intended to support the following related system Recommendations:

49. عليرضا ربيعي سرپرست گروه مطالعاتي 15 G.657 • The meaning of the terms used in this Recommendation and the guidelines to be followed in the measurement to verify the various characteristics are given in [ITU-T G.650.1] and [ITU‑T G.650.2]. • The characteristics of these fibre categories, including the definitions of the relevant parameters, their test methods and relevant values, will be refined as studies and experience progress.

50. عليرضا ربيعي سرپرست گروه مطالعاتي 15 Supplement 47 General aspects of optical fibres and cables Summary: • Supplement 47 to ITU-T G-series Recommendations provides information on the general transmission characteristics of single-mode optical fibres and cables specified in the ITU-T G.65x-series of Recommendations related to the practical use condition. • It covers the environmental and length-related characteristic of ITU-T G.65x-series optical fibres and cables. • Thefibre material-related characteristics are also described in Appendix I. • Version 2 of this supplement introduces the general aspect of multi-path interference (MPI) in an optical fibre in order to support newly established test methods for coherent MPI which can be found in Appendix IV of Recommendation ITU-T G.650.1.