GB/T 51152-2015 in English

1 General Provisions

1.0.1 Where it is difficult to implement this code in certain circumstances, a full account of the reasons why this code is not to be implemented and an alternative solution shall be submitted to the competent authorities for approval.

1.0.2 For extension or renovation projects, the extended or renovated parts may be consistent with the original project.Since most of the existing WDM systems are single-fiber unidirectional systems, all the provisions of this code on system design and optical line interface are applicable to single-fiber unidirectional systems.This code does not contain provisions on L-band as it is rarely used in practice.

1.0.3 Engineering design shall be carried out based on overall planning, joint construction, and resource sharing to meet the requirement of building a resource-conservation and environmenta friendly society.

1.0.4 On the basis of ensuring communication quality, multiple engineering design schemes shall be raised and compared so as to enhance economic efficiency and reduce project cost.

1.0.5 WDM optical fiber transmission system engineering design shall comply with not only the requirements stipulated in this code, but also those in the current relevant ones of the nation.
2 Terms and Abbreviations
2.1 Terms

2.1.1
this is the general definition of C-band.In fact, extensions from the two edges are still seen as Cband.A wavelength belongs to C-band as long as it falls in the range of 1527nm-1569nm specified in the DWDM system wavelength allocation plan defined in Article 3.4.1 of this code.

2.1.2
l-band long wavelength band
l-band refers to the wavelength band of 1565nm-1625nm.

2.1.3
optical channel
in the optical multiplex section, an optical channel is a passage through which optical signals are unidirectionally transmitted.

2.1.4
nominal central frequency (wavelength)
A nominal central frequency (wavelength) is defined as a frequency (wavelength) allocated at a certain frequency interval in the WDM system, with 193.10THz (1552.52nm vacuum wavelength) as the reference frequency (wavelength).

2.1.5
the "optical path"mentioned in this code refers to a transmission path between two points that is formed by end-to-end connection of the channels or tributary channels of one or more than one optical multiplex sections, such as main paths, end-to-end optical paths, etc., with an emphasis on service carrying characteristics.

2.1.6
optical booster amplifier
An optical booster amplifier is an optical amplifier used behind the multiplexer of the transmitter of the WDM system to boost the system s transmitting optical power.

2.1.7
optical pre-amplifier
an optical pre-amplifier is an optical amplifier used in front of the demultiplexer of the receiver of the WDM system to improve signal reception sensitivity.

2.1.8
optical line amplifier
an optical line amplifier is an optical amplifier used between passive optical fiber segments to compensate for fiber loss and extend the length of passive relay transmission.

2.1.9
optical amplifier span
an optical amplifier span is a transmission entity between adjacent optical line amplifier stations (OLA stations) , or between an optical terminal multiplexer station (OTM station) and the adjacent OLA station, or between an optical add-drop multiplexer station (OADM station) and the adjacent OLA station, constituting a transmission span used to extend the distance of passive relay.

2.1.10
optical multiplex section
an optical multiplex section is a transmission segment with electrical regenerative relay functions between adjacent OTM stations or OADM stations, or between an OTM station and the adjacent OADM station.

2.1.11
raman amplifier
a Raman amplifier is an optical amplifier used to amplify signals based on the stimulated Raman scattering (SRS) effect of the transmission fibers of the WDM system.

2.1.12
(optical) coherent detection
(optical) coherent detection refers to detecting and receiving carrier signals phase information by means of coherently mixing the local optical carrier signal and the optical carrier signals of the same frequency in the receiving device.

2.1.13
ultra-long-haul DWDM system
an ultra-long-haul DWDM system is a multi-span 40/80×10G DWDM system with a target distance of more than 1000km, or a single-span 40/80×10G DWDM system with a target distance of more than 160km.

2.1.14
when the eye diagram, extinction ratio, Sn-point optical return loss, receiver connector degradation, measurement tolerance and other conditions of the transmitter are the worst, and the receiver s input power lies between the maximum and minimum input powers, the receiver s OSNR must satisfy its OSNR tolerance.Nonlinear effects, chromatic dispersion (CD) , PMD, polarization dependent loss (PDL) , optical channel reflection and crosstalk, etc., are not considered in the defining receiver OSNR tolerance.These effects are considered in optical path OSNR penalty.Depending on whether aging effects are considered, the specific values of receiver OSNR tolerance are categorized into BOL and EOL.
3 System Configuration and Categorization
3.1 Characteristics of WDM System

3.1.1 According to channel spacing, WDM systems are categorized into DWDM systems and CWDM system.The former s channel spacing is not greater than 200GHz, and the latter s is greater than 200GHz.The DWDM systems mentioned in this code mainly refer to 40/80 channels systems.The 16/32/48 channels DWDM systems have the same parameters as the 40 channels system；and the 96 channels DWDM system has the same parameters as the 80 channels system.

3.1.2 Some WDM systems also support other types of client interfaces such as Fiber Channel (FC) , Enterprise Systems Connection (ESCON) and digital video.These interfaces are not defined in this code for the time being.

3.1.3 With the increase in FEC overhead, the upper limit of 100G of channel rate may further increase.1.25G is only used for CWDM systems.WDM systems with other channel rates are not included in this code.

3.2 System Configuration

3.2.1 Here, it refers to open WDM systems.Based on whether an OTU is used, WDM transmission systems are structurally classified into open WDM systems and integrative WDM systems.The client equipment of the latter directly provides signals of standard wavelengths, without using an OTU.All the WDM systems mentioned in this code refer to open WDM systems.

3.3 Application Codes

3.3.1 The application codes of this code is formulated mainly based on YD/T 1960-2009 Technical Requirements for Ultra-long-haul N×10Gbit/s Wavelength Division Multiplexing (WDM) Systems, D/T 1991-2009 Technical Requirements for N×40Gbit/s Optical Wavelength Division Multiplexing (WDM) Systems, and YD/T 2485-2013 Technical Requirements for N×100Gbit/s Optical Wavelength Division Multiplexing (WDM) Systems, and unify and integrate those of other related standards.

3.3.2 The application codes specified in this article are commonly-used ones.Given in Table1 is a comparison between the current application codes used in this code and the original ones used in YD/T 1060-2000 Technical Requirements of Optical Wavelength Division Multiplexing (WDM) System—32×2.5Gbit/s Part, YD/T 1143-2001 Technical Requirements of Optical Wavelength Division Multiplexing (WDM) System-16×10Gbit/s and 32×10Gbit/s Parts, and YD/T 1274-2003 Technical Specification for Optical Wavelength Division Multiplexing (WDM) System-160×10Gbit/s and 80×10Gbit/s Parts.

3.3.3 The application codes of CWDM system shall be denoted by the character sequences"nWx-ytz", and the meaning and value of each character shall be in accordance with those specified in Table 3.3.3.For single-fiber bidirectional systems, character"B"shall be placed in front of the application code.For systems with FEC, character"F"may be added to the end of the application code.