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docs: flexgrid

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Co-authored-by: Esther Lerouzic <esther.lerouzic@orange.com>
Change-Id: If38b56a39e083deec0563f25a2b575788dcedc43
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Jan Kundrát
2022-11-26 16:11:54 +01:00
committed by Jan Kundrát
parent 50d4ecd700
commit b1067a6266
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@@ -411,9 +411,9 @@ Span configuration is not a list (which may change in later releases) and the us
SpectralInformation
~~~~~~~~~~~~~~~~~~~
The user can only modify the value of existing parameters.
It defines a spectrum of N identical carriers.
While the code libraries allow for different carriers and power levels, the current user parametrization only allows one carrier type and one power/channel definition.
GNPy requires a description of all channels that are propagated through the network.
Flexgrid channel partitioning is available since the 2.7 release via the extra ``--spectrum`` option.
In the simplest case, homogeneous channel allocation can be defined via the ``SpectralInformation`` construct which defines a spectrum of N identical carriers:
+----------------------+-----------+-------------------------------------------+
| field | type | description |
@@ -479,3 +479,82 @@ While the code libraries allow for different carriers and power levels, the curr
| ``sys_margins`` | (number) | In dB. Added margin on min required |
| | | transceiver OSNR. |
+----------------------+-----------+-------------------------------------------+
.. _mixed-rate:
Arbitrary channel definition
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Non-uniform channels are defined via a list of spectrum "partitions" which are defined in an extra JSON file via the ``--spectrum`` option.
In this approach, each partition is internally homogeneous, but different partitions might use different channel widths, power targets, modulation rates, etc.
+----------------------+-----------+-------------------------------------------+
| field | type | description |
+======================+===========+===========================================+
| ``f_min``, | (number) | In Hz. Mandatory. |
| ``f_max`` | | Define partition :math:`f_{min}` is |
| | | the first carrier central frequency |
| | | :math:`f_{max}` is the last one. |
| | | :math:`f_{min}` -:math:`f_{max}` |
| | | partitions must not overlap. |
| | | |
| | | Note that the meaning of ``f_min`` and |
| | | ``f_max`` is different than the one in |
| | | ``SpectralInformation``. |
+----------------------+-----------+-------------------------------------------+
| ``baud_rate`` | (number) | In Hz. Mandatory. Simulated baud rate. |
+----------------------+-----------+-------------------------------------------+
| ``slot_width`` | (number) | In Hz. Carrier spectrum occupation. |
| | | Carriers of this partition are spaced at |
| | | ``slot_width`` offsets. |
+----------------------+-----------+-------------------------------------------+
| ``roll_off`` | (number) | Pure number between 0 and 1. Mandatory |
| | | TX signal roll-off shape. Used by |
| | | Raman-aware simulation code. |
+----------------------+-----------+-------------------------------------------+
| ``tx_osnr`` | (number) | In dB. Optional. OSNR out from |
| | | transponder. Default value is 40 dB. |
+----------------------+-----------+-------------------------------------------+
| ``delta_pdb`` | (number) | In dB. Optional. Power offset compared to |
| | | the reference power used for design |
| | | (SI block in equipment library) to be |
| | | applied by ROADM to equalize the carriers |
| | | in this partition. Default value is 0 dB. |
+----------------------+-----------+-------------------------------------------+
For example this example:
.. code-block:: json
{
"SI":[
{
"f_min": 191.4e12,
"f_max":193.1e12,
"baud_rate": 32e9,
"slot_width": 50e9,
"roll_off": 0.15,
"tx_osnr": 40
},
{
"f_min": 193.1625e12,
"f_max":195e12,
"baud_rate": 64e9,
"delta_pdb": 3,
"slot_width": 75e9,
"roll_off": 0.15,
"tx_osnr": 40
}
]
}
...defines a spectrum split into two parts.
Carriers with central frequencies ranging from 191.4 THz to 193.1 THz will have 32 GBaud rate and will be spaced by 50 Ghz.
Carriers with central frequencies ranging from 193.1625 THz to 195 THz will have 64 GBaud rate and will be spaced by 75 GHz with 3 dB power offset.
If the SI reference carrier is set to ``power_dbm`` = 0dBm, and the ROADM has ``target_pch_out_db`` set to -20 dBm, then all channels ranging from 191.4 THz to 193.1 THz will have their power equalized to -20 + O dBm (due to the O dB power offset).
All channels ranging from 193.1625 THz to 195 THz will have their power equalized to -20 + 3 = -17 dBm (total power signal + noise).
Note that first carrier of the second partition has center frequency 193.1625 THz (its spectrum occupation ranges from 193.125 THz to 193.2 THz).
The last carrier of the second partition has center frequency 193.1 THz and spectrum occupation ranges from 193.075 THz to 193.125 THz.
There is no overlap of the occupation and both share the same boundary.