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YD/T 3621 consists of the following parts under the general title Nx25Gbit/s WDM-PON for 5G mobile fronthaul.
—— Part 1: General requirements.
—— Part 2: PMD requirements.
—— Part 3: Management requirements.
This part is Part 2 of YD/T 3621.
This part is developed in accordance with the rules given in GB/T 1.1- 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This part was proposed by and is under the jurisdiction of China Communications Standards Association.
Nx25Gbit/s WDM-PON for 5G mobile fronthaul - Part 2: PMD requirements
1 Scope
This part specifies the physical layer, transceiver index and performance index requirements of the wavelength routing-based N×25Gbit/s WDM-PON system facing the load-bearing requirements of 5G mobile fronthaul network.
This part is applicable to the wavelength routing-based N×25Gbit/s WDM-PON equipment under the environment of public telecommunication network. It may be used as reference for the private telecommunication network.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 9771.1 Single-mode optical fibres for telecommunication - Part 1: Characteristics of a dispersion unshifted single-mode optical fibre
IEEE 802.3cc-2017 IEEE Standard for Ethernet - Amendment 11: Physical Layer and Management Parameters for Serial 25 Gbit/s Ethernet Operation Over Single-Mode Fiber
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
wavelength channel
unidirectional optical communication channel of the only or a group of center frequencies mapped to one branch port of AAWG
3.2
channel spacing
in a given reference grid, the absolute difference between the nominal frequencies of two adjacent wavelength channels
3.3
extinction ratio (ER)
for the digital on-off keying signal generated by the optical transmitter, the extinction ratio is the ratio of the average optical power of the high-level binary digital center point to the average optical power of the low-level binary digital center point
3.4
fibre distance
the total length of the fibre between the reference points R/S and S/R-CG (where applicable, the fiber includes the equivalent fiber representing the introduction of the delay component)
3.5
mask of transmitter eye diagram
a general method of characterizing a transmitter pulse waveform, which includes a specification of each of the following indexes to ensure the appropriate coordination between the transmitter and the receiver, the indexes include rise time, fall time, positive/negative pulse, ringing and jitter. At the appropriate reference points (S/R-CG for downlink, R/S for uplink), the transmitter eye diagram shall meet the requirements of transmitter mask
3.6
mean launch optical power
the single wavelength channel optical power at the corresponding reference point, representing the mean optical power in the characteristics of the optical transmitter. Wherein the optical signal transmitted to the fibre carries a given digital sequence. When expressing the range, the minimum mean launch optical power provides the power level that the transmitter shall always maintain, and the maximum mean launch optical power provides the power level that the transmitter shall never exceed
3.7
central frequency
a specified frequency of a wavelength channel
3.8
optical path loss
optical power loss caused by optical signals transmitting in ODN. Losses are caused by the following factors, including fibres, connectors, splices, dividers, wavelength couplers, attenuation, and other passive optical devices. ODN optical path loss in this part is the loss in any direction between reference point S/R-CG and reference point R/S
3.9
optical return loss (ORL)
the total reflectance value at the source reference point of the optical signal transmission path, measured by the ratio of the transmitted optical power to the reflected optical power
3.10
overload
a receiver parameter equivalent to the maximum average received optical power when a specified BER reference level is generated. Although the single wavelength channel optical power is measured based on the worst scene signal at the appropriate reference point (S/R-CG for uplink direction, R/S for downlink direction), it does not include optical path impairment
3.11
reflectance
the ratio of the reflected optical power to the incident optical power existing at a discrete reflection point
3.12
sensitivity
a receiver parameter equivalent to the minimum average received optical power when a specified BER reference level is generated. Although the above-mentioned single wavelength channel optical power is measured based on the worst scene signal at the appropriate reference point (S/R-CG for uplink direction, R/S for downlink direction), it does not include optical path impairment
3.13
tuning time
the time difference between the moment at which a tunable device deviates from its source wavelength channel and the moment at which it reaches the target wavelength channel
4 Abbreviations
For the purposes of this document, the following abbreviations apply.
AAWG Athermal Arrayed Waveguide Grating
BER Bit Error Rate
CT Channel Terminal
FEC Forward Error Correction
NRZ Non Return Zero
OA Optical Amplifier
ODN Optical Distribution Network
OLT Optical Line Terminal
ONU Optical Network Unit
ORL Optical Return Loss
PMD Physical Medium Dependent
PON Passive Optical Network
SNI Service Network Interface
UNI User Network Interface
WDM Wavelength Division Multiplexing
WDM-PON Wavelength Division Multiplexing-Passive Optical Network
WM Wavelength Multiplexer
5 ODN configuration of N×25Gbit/s WDM-PON system
ODN of Nx25Gbit/s WDM-PON for 5G mobile fronthaul adopts a point-to-multipoint network structure and consists of passive optical devices such as single-mode fibre, athermal arrayed waveguide grating (AAWG), and optical connector, providing optical transmission medium for physical connection between OLT and ONU, and realizing wavelength routing function between main fibre and branch fibre. The N×25Gbit/s WDM-PON system provides the ONU connected with each branch port (connecting with branch fibre) with a corresponding fixed working wavelength through AAWG in ODN (i.e., the ONU working wavelength is determined by its physical connection with the branch port of AAWG). The reference configuration of N×25Gbit/s WDM-PON system is shown in Figure 1.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Abbreviations
5 ODN configuration of N×25Gbit/s WDM-PON system
6 Physical media dependent (PMD) layer requirements for N×25Gbit/s WDM-PON
6.1 Line rate
6.2 FEC coding
6.3 Physical media and transmission mode
6.4 Line code
6.5 Working wavelength
6.6 Physical media dependent parameters
6.7 Requirements of transmitter at reference point S
