Strengthen WDM and IM/DD optical tests
This commit is contained in:
Silas Oettinghaus
@@ -6,6 +6,7 @@ classdef IMDD_base_system_minimal_integration_test < IMDDTestCase
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% - the reduced end-to-end chain runs without errors
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% - key signal objects have the expected lengths and sampling rates
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% - the DSP outputs return finite, bounded metrics
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% - the intermediate optical and electrical stages stay physically sane
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% - MLSE does not regress relative to the preceding FFE stage
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%
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% Thresholds are intentionally provisional in this first iteration.
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@@ -19,7 +20,7 @@ classdef IMDD_base_system_minimal_integration_test < IMDDTestCase
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function runReducedImddWorkflowOnce(testCase)
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% Run the deterministic reduced workflow once and share the
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% resulting signals/metrics across all test methods.
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testCase.workflow = runReducedWorkflow();
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testCase.workflow = buildReducedImddWorkflow("minimal");
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end
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end
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@@ -31,18 +32,30 @@ classdef IMDD_base_system_minimal_integration_test < IMDDTestCase
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testCase.verifyClass(wf.Symbols, 'Informationsignal');
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testCase.verifyClass(wf.Digi_sig, 'Informationsignal');
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testCase.verifyClass(wf.El_sig, 'Electricalsignal');
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testCase.verifyClass(wf.Opt_sig_tx, 'Opticalsignal');
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testCase.verifyClass(wf.Opt_sig, 'Opticalsignal');
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testCase.verifyClass(wf.Rx_sig_after_pd, 'Electricalsignal');
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testCase.verifyClass(wf.Scpe_sig_pre_mf, 'Informationsignal');
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testCase.verifyClass(wf.Scpe_sig, 'Informationsignal');
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testCase.verifyClass(wf.Synced_sig_centered, 'Informationsignal');
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testCase.verifyClass(wf.Synced_sig, 'Informationsignal');
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testCase.verifyGreaterThan(length(wf.Tx_bits.signal), 0);
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testCase.verifyGreaterThan(length(wf.Symbols.signal), 0);
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testCase.verifyEqual(wf.Digi_sig.fs, wf.params.fdac);
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% Tx_bits is a bit-level container and does not carry a
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% sampling-rate contract on this path.
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testCase.verifyEqual(wf.Symbols.fs, wf.params.fsym);
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testCase.verifyEqual(wf.El_sig.fs, wf.params.fdac * wf.params.kover);
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testCase.verifyEqual(wf.Opt_sig_tx.fs, wf.El_sig.fs);
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testCase.verifyEqual(wf.Opt_sig.fs, wf.Opt_sig_tx.fs);
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testCase.verifyEqual(wf.Rx_sig_after_pd.fs, wf.Opt_sig.fs);
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testCase.verifyEqual(wf.Scpe_sig_pre_mf.fs, wf.params.fadc);
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% After the matched filter, the signal is intentionally reduced
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% to 2 samples per symbol for the downstream DSP chain.
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testCase.verifyEqual(wf.Scpe_sig.fs, 2 * wf.params.fsym);
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testCase.verifyEqual(wf.Synced_sig_centered.fs, 2 * wf.params.fsym);
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testCase.verifyEqual(wf.Synced_sig.fs, 2 * wf.params.fsym);
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% The synchronized signal is explicitly cropped to 2 samples per
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@@ -56,9 +69,12 @@ classdef IMDD_base_system_minimal_integration_test < IMDDTestCase
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finiteSignals = {
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wf.Digi_sig.signal
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wf.El_sig.signal
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wf.Opt_sig_tx.signal
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wf.Opt_sig.signal
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wf.Rx_sig_after_pd.signal
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wf.Scpe_sig_pre_mf.signal
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wf.Scpe_sig.signal
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wf.Synced_sig_centered.signal
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wf.Synced_sig.signal
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};
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@@ -68,6 +84,20 @@ classdef IMDD_base_system_minimal_integration_test < IMDDTestCase
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testCase.verifyFalse(any(isinf(sig), 'all'));
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end
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txOptPower = signalPower(wf.Opt_sig_tx.signal);
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fiberOptPower = signalPower(wf.Opt_sig.signal);
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pdPower = signalPower(wf.Rx_sig_after_pd.signal);
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preMfVariance = signalVariance(wf.Scpe_sig_pre_mf.signal);
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mfVariance = signalVariance(wf.Scpe_sig.signal);
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centeredMean = mean(wf.Synced_sig_centered.signal(:));
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testCase.verifyGreaterThan(txOptPower, 0);
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testCase.verifyGreaterThan(fiberOptPower, 0);
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testCase.verifyGreaterThan(pdPower, 0);
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testCase.verifyGreaterThan(preMfVariance, 0);
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testCase.verifyGreaterThan(mfVariance, 0);
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testCase.verifyLessThanOrEqual(abs(centeredMean), 1e-12);
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testCase.verifyGreaterThanOrEqual(wf.ffe_results.metrics.BER, 0);
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testCase.verifyLessThanOrEqual(wf.ffe_results.metrics.BER, 1);
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testCase.verifyGreaterThanOrEqual(wf.mlse_results.metrics.BER, 0);
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@@ -105,217 +135,11 @@ classdef IMDD_base_system_minimal_integration_test < IMDDTestCase
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end
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end
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end
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function workflow = runReducedWorkflow()
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params = reducedWorkflowParameters();
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% -------------------- TX --------------------
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txPulse = Pulseformer( ...
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"fsym", params.fsym, ...
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"fdac", params.fdac, ...
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"pulse", "rrc", ...
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"pulselength", 12, ...
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"alpha", params.rcalpha);
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[digiSig, symbols, txBits] = PAMsource( ...
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"fsym", params.fsym, ...
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"M", params.M, ...
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"order", params.sourceOrder, ...
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"useprbs", false, ...
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"fs_out", params.fdac, ...
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"applyclipping", false, ...
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"applypulseform", true, ...
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"pulseformer", txPulse, ...
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"randkey", params.randomKey, ...
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"duobinary_mode", db_mode.no_db, ...
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"mrds_code", 0).process();
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elSig = AWG( ...
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"fdac", params.fdac, ...
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"f_cutoff", params.fsym, ...
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"lpf_active", false, ...
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"kover", params.kover, ...
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"bit_resolution", 8, ...
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"upsampling_method", "samplehold", ...
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"precomp_sinc_rolloff", 1).process(digiSig);
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elSig = elSig.normalize("mode", "oneone");
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elSig = elSig .* params.driverScaling;
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% -------------------- Optical Channel --------------------
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optSig = EML( ...
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"mode", eml_mode.im_cosinus, ...
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"power", params.opticalPowerDbm, ...
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"fsimu", elSig.fs, ...
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"lambda", params.laserWavelengthNm, ...
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"bias", params.vbias, ...
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"u_pi", params.uPi, ...
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"linewidth", 0, ...
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"randomkey", params.randomKey + 1, ...
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"alpha", 0).process(elSig);
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optSig = Fiber( ...
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"fsimu", optSig.fs, ...
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"fiber_length", params.linkLengthKm, ...
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"alpha", params.fiberAlphaDbPerKm, ...
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"D", 0, ...
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"lambda0", 1310, ...
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"gamma", 0, ...
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"Dslope", 0.07).process(optSig);
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rxOptSig = Amplifier( ...
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"amp_mode", "ideal_no_noise", ...
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"gain_mode", "output_power", ...
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"amplification_db", params.ropDbm).process(optSig);
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rxSigAfterPd = Photodiode( ...
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"fsimu", params.fdac * params.kover, ...
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"dark_current", 0, ...
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"responsivity", 1, ...
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"temperature", 20, ...
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"nep", 0, ...
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"randomkey", params.randomKey + 2).process(rxOptSig);
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rxSigFiltered = Filter( ...
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"filtdegree", 4, ...
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"f_cutoff", params.rxElectricalBandwidthHz, ...
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"fs", params.fdac * params.kover, ...
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"filterType", filtertypes.butterworth, ...
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"active", true).process(rxSigAfterPd);
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scopeLpf = Filter( ...
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"filtdegree", 4, ...
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"f_cutoff", params.scopeBandwidthHz, ...
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"fs", params.fadc, ...
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"filterType", filtertypes.butterworth, ...
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"active", true);
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scpeSig = Scope( ...
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"fsimu", params.fdac * params.kover, ...
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"fadc", params.fadc, ...
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"delay", 0, ...
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"fixed_delay", 0, ...
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"filtertype", filtertypes.butterworth, ...
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"samplingdelay", 0, ...
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"rand_samplingdelay", 0, ...
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"freq_offset", 0, ...
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"samp_jitter", 0, ...
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"adcresolution", 8, ...
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"quantbuffer", 0.1, ...
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"block_dc", 1, ...
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"lpf_active", 1, ...
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"H_lpf", scopeLpf).process(rxSigFiltered);
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rxMatchedFilter = Pulseformer( ...
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"fsym", params.fsym, ...
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"fdac", 2 * params.fsym, ...
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"pulse", "rrc", ...
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"pulselength", 12, ...
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"alpha", params.rcalpha, ...
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"matched", 1);
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scpeSig = rxMatchedFilter.process(scpeSig);
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[syncedSig, ~] = scpeSig.tsynch("reference", symbols, "fs_ref", params.fsym, "debug_plots", 0);
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syncedSig = syncedSig - mean(syncedSig.signal);
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syncedSig.signal = syncedSig.signal(1 : 2 * length(symbols));
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% -------------------- DSP --------------------
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ffeEq = FFE( ...
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"epochs_tr", 2, ...
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"epochs_dd", 1, ...
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"len_tr", params.lenTr, ...
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"mu_dd", 1e-4, ...
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"mu_tr", 1e-2, ...
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"order", 21, ...
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"sps", 2, ...
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"decide", 0, ...
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"adaption_technique", adaption_method.nlms, ...
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"dd_mode", 1);
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ffeResults = ffe( ...
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ffeEq, ...
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params.M, ...
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syncedSig, ...
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symbols, ...
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txBits, ...
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"precode_mode", db_mode.no_db, ...
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"showAnalysis", 0, ...
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"postFFE", [], ...
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"eth_style_symbol_mapping", 0);
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mlseEq = FFE( ...
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"epochs_tr", 2, ...
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"epochs_dd", 1, ...
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"len_tr", params.lenTr, ...
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"mu_dd", 1e-4, ...
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"mu_tr", 1e-2, ...
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"order", 21, ...
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"sps", 2, ...
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"decide", 0, ...
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"adaption_technique", adaption_method.nlms, ...
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"dd_mode", 1);
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postfilter = Postfilter("ncoeff", 1, "useBurg", 1);
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mlse = MLSE( ...
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"duobinary_output", 0, ...
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"M", params.M, ...
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"trellis_states", PAMmapper(params.M, 0).levels);
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[vnleResults, mlseResults] = vnle_postfilter_mlse( ...
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mlseEq, ...
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postfilter, ...
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mlse, ...
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params.M, ...
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syncedSig, ...
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symbols, ...
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txBits, ...
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"precode_mode", db_mode.no_db, ...
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"showAnalysis", 0, ...
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"postFFE", [], ...
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"eth_style_symbol_mapping", 0);
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workflow = struct();
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workflow.params = params;
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workflow.Digi_sig = digiSig;
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workflow.Symbols = symbols;
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workflow.Tx_bits = txBits;
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workflow.El_sig = elSig;
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workflow.Opt_sig = optSig;
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workflow.Rx_sig_after_pd = rxSigAfterPd;
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workflow.Scpe_sig = scpeSig;
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workflow.Synced_sig = syncedSig;
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workflow.ffe_results = ffeResults;
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workflow.vnle_results = vnleResults;
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workflow.mlse_results = mlseResults;
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function p = signalPower(signal)
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p = mean(abs(signal(:)).^2);
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end
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function params = reducedWorkflowParameters()
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params = struct();
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% Smaller, deterministic version of the IM/DD base workflow.
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params.M = 4;
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params.fsym = 16e9;
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params.fdac = 64e9;
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params.fadc = 64e9;
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params.kover = 2;
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params.randomKey = 1;
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params.sourceOrder = 12;
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params.rcalpha = 0.05;
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params.lenTr = 256;
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% Driver / modulator operating point.
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params.uPi = 3;
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params.vbiasRel = 0.5;
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params.vbias = -params.vbiasRel * params.uPi;
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params.driverScaling = 0.6 * (params.uPi / 2 - abs(params.vbias - params.uPi / 2));
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% Optical path.
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params.laserWavelengthNm = 1293;
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params.opticalPowerDbm = 3;
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params.linkLengthKm = 1;
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params.fiberAlphaDbPerKm = 0.3;
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params.ropDbm = 0;
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% Receiver filtering.
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params.rxElectricalBandwidthHz = 40e9;
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params.scopeBandwidthHz = 25e9;
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function v = signalVariance(signal)
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centered = signal(:) - mean(signal(:));
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v = mean(abs(centered).^2);
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end
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