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Add AWGN channel models and route IMDD simulation through them

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This commit is contained in:
Silas Oettinghaus
2026-03-26 11:23:07 +01:00
parent d3235a5c9c
commit c135cb76b1
7 changed files with 167 additions and 68 deletions
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28
projects/IMDD_base_system/imdd_it.m
View File

@@ -15,7 +15,7 @@ close all;
if 1
uloops = struct;
uloops = struct;
uloops.precomp = [0];
uloops.bitrate = [300].*1e9; %[300,330,360,390,420,450,480] [224,336,360,390,420,448] for MPI
% uloops.laser_wavelength = [1293,1297.5,1302,1306.5,1310,1313.4,1318,1322.7,1327.4];
@@ -23,30 +23,36 @@ if 1
uloops.M = [4];
uloops.link_length = 1;
% uloops.link_length = [0:2:10]; % 1,2,3,5,6,8,10
uloops.alpha = [0];
uloops.duob_mode = db_mode.db_precoded;
uloops.channel_alpha = [0.5];
uloops.duob_mode = db_mode.no_db;
uloops.decoding_mode = "memoryless";
uloops.channel_mode = "awgn_alphad";
uloops.channel_snr_dB = [20:-2:0];
wh = DataStorage(uloops);
wh.addStorage("ber");
wh = submit_handle(@imdd_model,wh,"parallel",0);
wh = submit_handle(@imdd_model,wh,"parallel",1);
end
%%
figure
hold on
for alpha = uloops.alpha
a=wh.getStoValue('ber',0, [300].*1e9 , 1293, 4, uloops.link_length,alpha,uloops.duob_mode,uloops.decoding_mode);
% ffe = cellfun(@(x) x.ffe_results.metrics.BER, a);
ffe = cellfun(@(x) x.dbt_results.metrics.BER, a);
plot(uloops.link_length,ffe,'DisplayName',sprintf('Alpha: %d',alpha),'LineStyle','-','HandleVisibility','on');
for alpha = uloops.channel_alpha
a=wh.getStoValue('ber',0, [300].*1e9 , 1293, 4, uloops.link_length,alpha,uloops.duob_mode,uloops.decoding_mode,uloops.channel_mode,uloops.channel_snr_dB);
gmi_ffe = cellfun(@(x) x.ffe_results.metrics.GMI, a);
alpha_ffe = cellfun(@(x) x.ffe_results.metrics.Alpha, a);
gmi_mlse = cellfun(@(x) x.mlse_results.metrics.GMI, a);
plot(uloops.channel_snr_dB,gmi_ffe,'DisplayName',sprintf(''),'LineStyle','-','HandleVisibility','on');
plot(uloops.channel_snr_dB,gmi_mlse,'DisplayName',sprintf(''),'LineStyle','-','HandleVisibility','on');
end
set(gca, 'YScale', 'log');
ylim([5e-5 0.4]);
yline([3.8e-3, 2e-2],'HandleVisibility','off');
% ylim([5e-5 0.5]);
% yline([3.8e-3, 2e-2],'HandleVisibility','off');
legend
beautifyBERplot()
ylabel('BER');

109
projects/IMDD_base_system/imdd_model.m
View File

@@ -32,6 +32,10 @@ tx_bw_nyquist = 0.8;
% Channel
link_length = 1;
channel_mode = "physical";
channel_snr_dB = 20;
channel_alpha = 0;
channel_delay_symbols = 1;
% RX
rop = -8;
@@ -46,7 +50,7 @@ dfe_order = [0 0 0];
pf_ncoeffs = 1;
alpha = 0;
eml_alpha = 0;
len_tr = 4096*2;
@@ -95,15 +99,12 @@ if fsym_ ~= fsym
end
f_nyquist = fsym/2;
Pform = Pulseformer("fsym",fsym,"fdac",4*fsym,"pulse","rc","pulselength",16,"alpha",rcalpha);
[Digi_sig,Symbols,Tx_bits] = PAMsource(...
"fsym",fsym,"M",M,"order",18,"useprbs",0,...
"fsym",fsym,"M",M,"order",16,"useprbs",0,...
"fs_out",fdac,...
"applyclipping",0,"clipfactor",1.5,...
"applypulseform",apply_pulsef,"pulseformer",Pform,...
@@ -113,52 +114,74 @@ Pform = Pulseformer("fsym",fsym,"fdac",4*fsym,"pulse","rc","pulselength",1
Digi_sig.spectrum("displayname",'Digi Spectrum','fignum',10,'normalizeTo0dB',1);
%%%%% AWG
% El_sig = M8199A("kover",kover).process(Digi_sig);
El_sig = AWG("fdac",fdac,"f_cutoff",fsym,"lpf_active",0,"kover",kover,"bit_resolution",12,"upsampling_method","samplehold","precomp_sinc_rolloff",1).process(Digi_sig);
% El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',0);
% El_sig = El_sig.setPower(0,"dBm");
%%%%% Low-pass el. components %%%%%%
tx_bwl = tx_bw_nyquist.*f_nyquist;
% tx_bwl = 80e9;
El_sig = Filter('filtdegree',4,"f_cutoff",tx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(El_sig);
% El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',1);
channel_mode = lower(string(channel_mode));
%%%%% Electrical Driver Amplifier %%%%%%
% El_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","gain","amplification_db",3).process(El_sig);
El_sig = El_sig.normalize("mode","oneone");
scaling = 0.6*(u_pi/2-abs(vbias-u_pi/2));
El_sig = El_sig .* scaling;
switch channel_mode
case "physical"
%%%%% MODULATE E/O CONVERSION %%%%%%
[Opt_sig] = EML("mode",eml_mode.im_cosinus,"power",3,"fsimu",El_sig.fs,"lambda",laser_wavelength,"bias",vbias,"u_pi",u_pi,"linewidth",laser_linewidth,"randomkey",random_key+1,"alpha",alpha).process(El_sig);
%%%%% AWG
% El_sig = M8199A("kover",kover).process(Digi_sig);
El_sig = AWG("fdac",fdac,"f_cutoff",fsym,"lpf_active",0,"kover",kover,"bit_resolution",12,"upsampling_method","samplehold","precomp_sinc_rolloff",1).process(Digi_sig);
% El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',0);
% El_sig = El_sig.setPower(0,"dBm");
% Opt_sig.spectrum("displayname",'Opt Spectrum','fignum',10,'normalizeTo0dB',1);
%%%%% Low-pass el. components %%%%%%
tx_bwl = tx_bw_nyquist.*f_nyquist;
% tx_bwl = 80e9;
El_sig = Filter('filtdegree',4,"f_cutoff",tx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(El_sig);
% El_sig.spectrum("displayname",'Digi Spectrum','fignum',100,'normalizeTo0dB',1);
Opt_sig = Fiber("fsimu",Opt_sig.fs,"fiber_length",link_length,"alpha",0.3,"D",0,"lambda0",1310,"gamma",0,"Dslope",0.07).process(Opt_sig);
%%%%% Electrical Driver Amplifier %%%%%%
% El_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","gain","amplification_db",3).process(El_sig);
El_sig = El_sig.normalize("mode","oneone");
scaling = 0.6*(u_pi/2-abs(vbias-u_pi/2));
El_sig = El_sig .* scaling;
%%%%%% ROP %%%%%%
Rx_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",rop).process(Opt_sig);
%%%%% MODULATE E/O CONVERSION %%%%%%
[Opt_sig] = EML("mode",eml_mode.im_cosinus,"power",3,"fsimu",El_sig.fs,"lambda",laser_wavelength,"bias",vbias,"u_pi",u_pi,"linewidth",laser_linewidth,"randomkey",random_key+1,"alpha",eml_alpha).process(El_sig);
%%%%%% PD Square Law %%%%%%
Rx_sig = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20,"nep",1.8e-11).process(Rx_sig);
% Opt_sig.spectrum("displayname",'Opt Spectrum','fignum',10,'normalizeTo0dB',1);
Opt_sig = Fiber("fsimu",Opt_sig.fs,"fiber_length",link_length,"alpha",0.3,"D",0,"lambda0",1310,"gamma",0,"Dslope",0.07).process(Opt_sig);
%%%%%% Low-pass RX (PD, El. Connectors and Scope %%%%%%
rx_bwl = rx_bw_nyquist.*f_nyquist;
% rx_bwl = 80e9;
Rx_sig = Filter('filtdegree',4,"f_cutoff",rx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(Rx_sig);
%%%%%% ROP %%%%%%
Rx_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",rop).process(Opt_sig);
% %%%%%% Low-pass Scope %%%%%%
Lp_scpe = Filter('filtdegree',4,"f_cutoff",110e9,"fs",fadc,"filterType",filtertypes.butterworth,"active",true);
%%%%%% PD Square Law %%%%%%
Rx_sig = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20,"nep",1.8e-11).process(Rx_sig);
% Rx_sig.spectrum("displayname",'Analog Rx Spectrum','fignum',100,'normalizeTo0dB',1);
%%%%%% Low-pass RX (PD, El. Connectors and Scope %%%%%%
rx_bwl = rx_bw_nyquist.*f_nyquist;
% rx_bwl = 80e9;
Rx_sig = Filter('filtdegree',4,"f_cutoff",rx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(Rx_sig);
%%%%%% Scope %%%%%%
Scpe_sig = Scope("fsimu",fdac*kover,"fadc",fadc,...
"delay",0,"fixed_delay",0,"filtertype",filtertypes.butterworth,...
"samplingdelay",0,"rand_samplingdelay",0,"freq_offset",0,"samp_jitter",0,...
"adcresolution",8,"quantbuffer",0.1,'block_dc',1,'lpf_active',1,'H_lpf',Lp_scpe).process(Rx_sig);
% %%%%%% Low-pass Scope %%%%%%
Lp_scpe = Filter('filtdegree',4,"f_cutoff",110e9,"fs",fadc,"filterType",filtertypes.butterworth,"active",true);
% Rx_sig.spectrum("displayname",'Analog Rx Spectrum','fignum',100,'normalizeTo0dB',1);
%%%%%% Scope %%%%%%
Rx_sig = Scope("fsimu",fdac*kover,"fadc",fadc,...
"delay",0,"fixed_delay",0,"filtertype",filtertypes.butterworth,...
"samplingdelay",0,"rand_samplingdelay",0,"freq_offset",0,"samp_jitter",0,...
"adcresolution",8,"quantbuffer",0.1,'block_dc',1,'lpf_active',1,'H_lpf',Lp_scpe).process(Rx_sig);
case "awgn"
Rx_sig = awgn_channel(Digi_sig, ...
"snr_dB", channel_snr_dB, ...
"randkey", random_key + 2);
case {"awgn_alphad", "awgn_1alphad", "awgn_1_plus_alpha_d"}
delaySamples = max(1, round(channel_delay_symbols * Digi_sig.fs / fsym));
Rx_sig = awgn_alpha_d_channel(Digi_sig, ...
"alpha", channel_alpha, ...
"delay_samples", delaySamples, ...
"snr_dB", channel_snr_dB, ...
"randkey", random_key + 2);
otherwise
error('Unknown channel_mode "%s". Supported: physical, awgn, awgn_alphaD.', channel_mode);
end
txPulseformer = [];
if apply_pulsef
@@ -171,9 +194,9 @@ dspParameters.mu_ffe = mu_ffe;
dspParameters.mu_dfe = mu_dfe;
dspParameters.mu_dc = mu_dc;
dspParameters.use_ffe = 1;
dspParameters.use_dfe = 1;
dspParameters.use_dfe = 0;
dspParameters.use_vnle_mlse = 1;
dspParameters.use_dbtgt = 1;
dspParameters.use_dbtgt = 0;
dspParameters.use_dbenc = 0;
dspParameters.use_ml_mlse = 0;
dspParameters.showAnalysis = 0;
@@ -187,7 +210,7 @@ dspParameters.ffe_order_dbtgt = [50, 0, 0];
dspParameters.dfe_order_dbtgt = dfe_order;
dspParameters.decoding_mode = decoding_mode;
scopeOutput = dsp_scope_signal(Scpe_sig, Symbols, Tx_bits, ...
scopeOutput = dsp_scope_signal(Rx_sig, Symbols, Tx_bits, ...
"fsym", fsym, ...
"M", M, ...
"duob_mode", duob_mode, ...