README.rst update

Add auto_design and equipment library description!

Signed-off-by: Jean-Luc Auge <jeanluc.auge@orange.com>

README.rst

@@ -97,7 +97,9 @@ example, to use the CORONET Continental US (CONUS) network defined in `examples/
 .. code-block:: shell
 
     $ cd examples
-    $ python3 transmission_main_example.py coronet_conus_example.json
+    $ python3 transmission_main_example.py CORONET_Global_Topology.json
+
+It is also possible to use an Excel file input (for example CORONET_Global_Topology.xls). The excel file will be parsed automatically into a json file with the same name prefix. How to prepare the Excel input file is explained `here <Excel_userguide.rst>`_.
 
 This script will calculate the average signal osnr and snr across 93 network
 elements (transceiver, ROADMs, fibers, and amplifiers) between Abilene, Texas
@@ -114,6 +116,97 @@ interference noise.
 .. |Pase| replace:: P\ :sub:`ase`
 .. |Pnli| replace:: P\ :sub:`nli`
 
+Design and transmission parameters are defined in a dedicated json file : examples/eqpt_config.json. This file defines the equipement librairies that can be customized at will:
+* Edfa:[]
+* Fiber:[]
+* Transceiver:[]
+It also defines the simulation parameters: 
+* Spans:[]
+* Roadms:[]
+* SI:[]
+
+**EQUIPMENT LIBRARY**
+* The Edfa equipment library is a list of supported amplifiers. New amplifiers can be added and existing ones removed at will by the user. It implements 3 different noise models:
+1- 'type_def' : 'variable_gain'
+  => simplified model simulating a 2 coils edfa with internal, input and output VOAs. The NF vs gain response is calculated accordingly based on the input parameters: nf_min, nf_max and gain_flatmax. It is not a simple interpolation but a 2 stages NF calculation.
+2- 'type_def' : 'fixed_gain'
+  fixed gain model: NF = Cte = nf0 if gain_min < gain < gain_flatmax
+3- 'type_def' : None
+  => advanced model: a detailed json configuration file is required 'advanced_config_from_json': 3rd order polynomial NF = f(gain), N-array NF_ripple = f(frequency), N-array gain_ripple = f(frequency), N-array dgt = f(frequency). Compared to the previous models, NF ripple and gain ripple are modelled.
+For all amplifier models:
+- 'type_variety' : a unique name to id the amplifier in the json or excel template topology input file.
+- 'out_voa_auto' : true/false 
+  => auto_design feature to optimize the amplifier output VOA. True: output VOA is present and will be used to push amplifier gain to its maximum, within EOL power margins. 
+- 'allowed_for_design' : toggle true/false. If False, the amplifier will not be picked by auto-design but it can still be used as a manual input (from json or excel template topology files).
+
+* The Fiber library currently describes SSMF but additional fiber types can be entered by the user, following the same model:
+- 'type_variety' : a unique name to id the fiber type in the json or excel template topology input file.
+- 'dispersion'  (s.m-1.m-1)
+- 'gamma' : 2pi.n2/(lambda*Aeff) (w-2.m-1)
+
+* The Transceiver equipment library is a list of supported transceivers. New transceivers can be added and existing ones removed at will by the user. It is used to determine the service list path feasibility when running the path_request_run.py routine.
+- 'type_variety': a unique name to id the transponder in the json or excel template service list input file. 
+- 'frequency' : min max excursion
+- 'mode' : a list of modes supported by the transponder. New modes can be added at will by the user. The modes are specific to each transponder type_variety. Each mode is described with:
+    - 'format' : a unique name to id the mode
+    - 'baud_rate' (Hz)
+    - 'OSNR' : min required OSNR in 0.1nm (dB)
+    - 'bit_rate' (bit/s)
+    - 'roll_off'
+
+**SIMULATION PARAMETERS**
+* Foreword (about auto_design): 
+- auto_design automatically creates Edfa amplifier network elements when they are missing: after a fiber, or between a ROADM and a fiber. This auto_design functionality can be manually and locally deactivated by introducing a Fused network elements after a Fiber or a Roadm that doesn't need amplification. The amplifier is chosen in the Edfa list of the equipment library based on gain, power and NF criteria. Only the Edfa with the toogle 'allowed_for_design' = true are considered.
+- For amplifier defined in the topology json input but whose gain = 0 (placeholder), auto_design will set its gain automatically: see power_mode in the Spans library to find out how the gain is calculated.
+
+* Spans configuration library. It is not a list (in the current code version) and the user can only modify the value of existing parameters:
+- 'power_mode': true/false
+    => false = gain mode: auto_design sets amplifier gain = preceeding span loss, unless the amplifier exists and its gain>0 in the topology input json.
+    => true = power mode (recommended for auto-design and power sweep): auto_design sets amplifier power according to delta_power_range (see after). If the amplifier exists with gain>0 in the topology json input, then its gain is translated into a power target/channel. Moreover, when performing a power sweep (see power_range_db in the SI configuration library) the power sweep is performed wrto this power target, regardless of preceeding amplifiers power saturation/limitations.
+- 'delta_power_range_db': auto-design only, power mode only, specifies the [min, max, step] power excursion / span. It is a relative power excursion wrto the power_dbm + power_range_db (power sweep if applicable) defined in the SI configuration library. This relative power excursion is = 1/3 of the span loss difference with the reference 20dB span. The 1/3 slope is derived from the GN model equations. For example :
+    => a 23dB span loss will be set to 1dB more power than a 20dB span loss. The 20dB reference spans will ALWAYS be set to power = power_dbm + power_range_db. 
+    => to configure the same power in all spans : [0,0,0]. All spans will be set to power = power_dbm + power_range_db
+    => to configure the same power in all spans and 3dB more power just for the longest spans: [0,3,3]. The longest spans are set to power = power_dbm + power_range_db + 3
+    => to configure a 4dB power range across all spans in 0.5dB steps: [-2,2,0.5]. A 17dB span is set to power=power_dbm+power_range_db-1, a 20dB span to power=power_dbm+power_range_db and a 23dB span to power=power_dbm+power_range_db+1
+- 'max_length': (length_units) split fiber lengths > max_length. Interest to support high level topologies that do not specify in line amplification sites. For example the CORONET_Global_Topology.xls defines links > 1000km between 2 sites: it couldn't be simulated if these links were not splitted in shorter span lengths.
+- 'length_unit': unit for max_length
+- 'max_loss' : not used in the current code implementation
+- 'padding' (dB) : min span loss before putting an attenuator before fiber. Attenuator value Fiber.att_in = max(0, padding-span_loss). Padding can be set manually to reach a higher padding value for a given fiber by filling in the Fiber/params/att_in field in the topology json input (or excel template):
+    =>   {"uid": "fiber (A1->A2)",
+          "type": "Fiber",
+          "type_variety": "SSMF",
+          "params": {
+            "type_variety": "SSMF",
+            "length": 120.0,
+            "loss_coef": 0.2,
+            "length_units": "km",
+            "att_in": 0,
+            "con_in": 0,
+            "con_out": 0 } }
+    => but if span_loss = length * loss_coef + att_in + con_in + con_out < padding, the specified att_in value will be completed to have span_loss = padding. Therefore it is not possible to set span_loss < padding.
+- 'EOL': all fiber span loss ageing. The value is added to the con_out (fiber output connector). So the design and the path feasibility are performed with span_loss + EOL. EOL cannot be set manually for a given fiber span (workaround is to specify higher con_out loss for this fiber).
+- 'con_in/out' : default values if Fiber/params/con_in/out is None in the topology input description. This default value is ignored if a Fiber/params/con_in/out value is input in the topology for a given Fiber.
+
+* Roadms configuration library. It is not a list of possible Roadm implementations (in the current code version) and the user can only modify the value of existing parmeters:
+- 'gain_mode_default_loss' : default value if Roadm/params/loss is None in the topology input description. This default value is ignored if a params/loss value is input in the topology for a given Roadm.
+- 'power_mode_pref' : power mode only,
+    => auto_design sets the power of Roadm ingress amplifiers to power_dbm + power_range_db, REGARDLESS OF EXISTING GAIN SETTINGS from the topology json input. 
+    => auto_design sets the Roadm loss so that its egress channel power = power_mode_pref, REGARDLESS OF EXISTINIG LOSS SETTINGS from the topology json input. It means that the ouput power from a ROADM (and therefore its OSNR contribution) is Cte and not depending from power_dbm and power_range_db sweep settings. This choice is meant to reflect some typical control loop algorithms.
+
+*SI (Spectrum Information) configuration library: it is not a list and 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:
+- 'f_min/max' (Hz): carrier min max excursion
+- 'baud_rate' (Hz): simulated baud rate
+- 'spacing' (Hz): carrier spacing
+- 'roll_off'
+- 'OSNR' : not used
+- 'bit_rate' : not used
+- 'power_dbm' : reference channel power,
+    => In gain mode (see Spans/power_mode = false), all gain settings are offset wrto this reference power. 
+    => In power mode, it is the reference power for Spans/delta_power_range_db: for example if delta_power_range_db = [0,0,0], the same power=power_dbm is launched in every spans. 
+    => The network design is performed with the power_dbm value: even if a power sweep is defined (see after) the design is not repeated.
+- 'power_range_db' : power sweep excursion around power_dbm. It is not the min and max channel power values! The reference power becomes : power_range_db + power_dbm.
+
+
 The `transmission_main_example.py <examples/transmission_main_example.py>`_
 script propagates a specrum of 96 channels at 32 Gbaud, 50 GHz spacing and 0
 dBm/channel. These are not yet parametrized but can be modified directly in the
@@ -125,7 +218,6 @@ element. The amplifier is currently defined with gain range of 15 dB to 25 dB
 and 21 dBm max output power. Ripple and NF models are defined in
 `examples/std_medium_gain_advanced_config.json <examples/std_medium_gain_advanced_config.json>`_
 
-It is possible to use an Excel file input. This will generate the json topology entry. How to prepare the Excel input file is explained `here <Excel_userguide.rst>`_.
 
 **Run multiple optimisation with path_requests_run.py**
 

examples/eqpt_config.json

@@ -92,14 +92,14 @@
                         },
             "mode":[
                        {
-                       "format": "PS_SP64_1",
+                       "format": "mode_1",
                        "baud_rate": 32e9,
                        "OSNR": 11,
                        "bit_rate": 100e9,
                        "roll_off": 0.15
                        },
                        {
-                       "format": "PS_SP64_2",
+                       "format": "mode_2",
                        "baud_rate": 66e9,
                        "OSNR": 15,
                        "bit_rate": 200e9,