Add a -spectrum option to input external file to define spectrum

The option is only set for gnpy-transmission-main.

The spectrum file is a list of spectrum objects, each defining
f_min, f_max and spectrum attributes using the same meaning as SI
in eqpt_config.json for baud_rate, roll_off, tx_osnr. slot_width is
used for the occupation of each carrier around their central frequency,
so slot_width corresponds to spacing of SI.
Unlike SI, the frequencies are defined includint f_min and f_max.
The partitions must be contiguous not overlapping.

Pref.p_span0 object records the req_power, while
ref_carrier records info that will be useful for equalization ie baud_rate.

For now, I have not integrated the possibility to directly use
transceivers type and mode in the list.

User can define sets of contiguous channels and a label to identify
the spectrum bands. If no label are defined, the program justs uses
the index + baud rate of the spectrum bands as label.

Print results per spectrum label

If propagated spectrum has mixed rates, then prints results (GSNR and OSNR)
for each propagated spectrum type according to its label.

Print per label channel power of elements

Per channel power prints were previously only showing the noiseless
reference channel power and only an average power.
With this change, we add a new information on the print:
the average total power (signal + noise + non-linear noise).
If there are several spectrum types propagating, the average per
spectrum is displayed using the label.
For this purpose, label and total power are recorded in each element
upon propagation

Note that the difference between this total power and the existing
channel power represents the added noise for the considered OMS.
Indeed ROADMs equalize per channel total power, so that power displayed
in 'actual pch (dBm)' may contain some noise contribution accumulated
with previous propagation.
Because 'reference pch out (dBm)' is for the noiseless reference,
it is exactly set to the target power and 'actual pch (dBm)' is always
matching 'reference pch out (dBm)' in ROADM prints.

Add examples and tests for -spectrum option

initial_spectrum1.json reproduces exactly the case of SI
initial_spectrum2.json sets half of the spectrum with 50GHz 32Gbauds and
half with 75GHz 64 Gbauds. Power setting is not set for the second half,
So that equalization will depend on ROADM settings.

Signed-off-by: EstherLerouzic <esther.lerouzic@orange.com>
Change-Id: Ibc01e59e461e5e933e95d23dacbc5289e275ccf7

gnpy/tools/cli_examples.py

@@ -14,6 +14,7 @@ import sys
 from math import ceil
 from numpy import linspace, mean
 from pathlib import Path
+
 import gnpy.core.ansi_escapes as ansi_escapes
 from gnpy.core.elements import Transceiver, Fiber, RamanFiber
 from gnpy.core.equipment import trx_mode_params
@@ -26,8 +27,8 @@ from gnpy.topology.request import (ResultElement, jsontocsv, compute_path_dsjctn
                                    deduplicate_disjunctions, compute_path_with_disjunction,
                                    PathRequest, compute_constrained_path, propagate)
 from gnpy.topology.spectrum_assignment import build_oms_list, pth_assign_spectrum
-from gnpy.tools.json_io import load_equipment, load_network, load_json, load_requests, save_network, \
-                               requests_from_json, disjunctions_from_json, save_json
+from gnpy.tools.json_io import (load_equipment, load_network, load_json, load_requests, save_network,
+                                requests_from_json, disjunctions_from_json, save_json, load_initial_spectrum)
 from gnpy.tools.plots import plot_baseline, plot_results
 
 _logger = logging.getLogger(__name__)
@@ -118,6 +119,7 @@ def transmission_main_example(args=None):
     parser.add_argument('-pl', '--plot', action='store_true')
     parser.add_argument('-l', '--list-nodes', action='store_true', help='list all transceiver nodes')
     parser.add_argument('-po', '--power', default=0, help='channel ref power in dBm')
+    parser.add_argument('--spectrum', type=Path, help='user defined mixed rate spectrum JSON file')
     parser.add_argument('source', nargs='?', help='source node')
     parser.add_argument('destination', nargs='?', help='destination node')
 
@@ -194,8 +196,16 @@ def transmission_main_example(args=None):
     if args.power:
         trx_params['power'] = db2lin(float(args.power)) * 1e-3
     params.update(trx_params)
+    initial_spectrum = None
+    nb_channels = automatic_nch(trx_params['f_min'], trx_params['f_max'], trx_params['spacing'])
+    if args.spectrum:
+        initial_spectrum = load_initial_spectrum(args.spectrum)
+        nb_channels = len(initial_spectrum)
+        print('User input for spectrum used for propagation instead of SI')
+    params['nb_channel'] = nb_channels
     req = PathRequest(**params)
-
+    req.initial_spectrum = initial_spectrum
+    print(f'There are {nb_channels} channels propagating')
     power_mode = equipment['Span']['default'].power_mode
     print('\n'.join([f'Power mode is set to {power_mode}',
                      f'=> it can be modified in eqpt_config.json - Span']))
@@ -226,9 +236,13 @@ def transmission_main_example(args=None):
             power_range = list(linspace(p_start, p_stop, p_num))
         except TypeError:
             print('invalid power range definition in eqpt_config, should be power_range_db: [lower, upper, step]')
-
     for dp_db in power_range:
         req.power = db2lin(pref_ch_db + dp_db) * 1e-3
+        # if initial spectrum did not contain any power, now we need to use this one.
+        # note the initial power defines a differential wrt req.power so that if req.power is set to 2mW (3dBm)
+        # and initial spectrum was set to 0, this sets a initial per channel delta power to -3dB, so that
+        # whatever the equalization, -3 dB is applied on all channels (ie initial power in initial spectrum pre-empts
+        # "--power" option)
         if power_mode:
             print(f'\nPropagating with input power = {ansi_escapes.cyan}{lin2db(req.power*1e3):.2f} dBm{ansi_escapes.reset}:')
         else: