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Equalizer with different DC removal positions

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This commit is contained in:
Silas Oettinghaus
2023-09-29 08:18:22 +02:00
parent 8b3bc688dd
commit fce274c4cf
6 changed files with 443 additions and 326 deletions
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275
setup_simulation.m
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@@ -1,26 +1,21 @@
sir_loop = -22;
lw = [0.1e6 1e6 10e6];
for lp = 1
dc_mu = 0.05;
rng(9);
sir = sir_loop(1);
%% A) Set Simulation Variables
rng(lp);
%% Set Simulation Variables
sir = sir;
delay = 20; %mpi delay in meter
sir = -18;
delay = 10; %mpi delay in meter
fiblen = 0; %main link in km
laser_linewidth =1e6;
laser_linewidth =5e6;
O = 17; %order of prbs
O = 18; %order of prbs
N = 2^(O-1); %length of prbs
[~,seed] = prbs(O,1); %initialize first seed of prbs
@@ -44,7 +39,8 @@ for lp = 1
fsimu = kover * fdac ;
%% CONSTRUCT ALL CLASSES
%% B) CONSTRUCT ALL CLASSES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
digimod = PAMmapper(M,0);
@@ -56,12 +52,12 @@ for lp = 1
u_pi = 3.5;
vbias = (0.5*u_pi)-u_pi;
extmodlaser = EML("mode",eml_mode.im_cosinus,"power",15,"fsimu",fsimu,"lambda",1550,"bias",vbias,"u_pi",u_pi,"linewidth",laser_linewidth);
extmodlaser = EML("mode",eml_mode.im_cosinus,"power",5,"fsimu",fsimu,"lambda",1550,"bias",vbias,"u_pi",u_pi,"linewidth",laser_linewidth);
fib = Fiber("fsimu",fdac*kover,"fiber_length",fiblen,"alpha",0.2,"D",16,"lambda0",thz2nm(193.1),"gamma",0);
reflectionpoint = Amplifier("amp_mode","ideal_no_noise","gain_mode","gain","amplification_db",sir);
reflectionprop = Fiber("fsimu",fdac*kover,"fiber_length",2*delay/1000,"alpha",0.2,"D",16,"lambda0",1550,"gamma",0);
reflectionprop = Fiber("fsimu",fdac*kover,"fiber_length",delay/1000,"alpha",0.2,"D",16,"lambda0",1550,"gamma",0);
opticatten = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",-8);
@@ -77,101 +73,157 @@ for lp = 1
eq = EQ("K",2,"plottrain",0,"plotfinal",0,...
"training_length",4096,"training_loops",2,...
"Ne",[50,5,3],"Nb",[3,2,2],...
"DCmu",dc_mu,"DDmu",[0.0004 0.0005 0.0006 0.0007 ],"DFEmu",0.005,"FFEmu",0.005,...
"DCmu",0.05,"DDmu",[0.0004 0.0005 0.0006 0.0007 ],"DFEmu",0.005,"FFEmu",0.005,...
"dd_loops",2,"epsilon",[10 100 1000 ],"M",2,...
"thres",[0.005 0.004 0.0005 ],"l1act",0,"delay",0,"rho",0.0005,"ideal_dfe",0,"DB_aim",0);
eq2 = EQ_silas("Ne",[50,5,0],"Nb",[3,2,0],"trainlength",4096,"mu_dc_dd",0.001,"mu_dc_train",0.05,"mu_ffe_train",0.005,"mu_combined_dd",[0.0004 0.0006 0.0003 0.005],"ddloops",5);
eq2 = EQ_silas("Ne",[30,0,0],"Nb",[3,0,0],"trainlength",4096,"mu_dc_dd",0.005,...
"mu_dc_train",0.05,"mu_ffe_train",0.005,"mu_combined_dd",[0.0004 0.0006 0.0003 0.005],"ddloops",3,'dcmode',3);
%% PROCESS
%% C) PROCESS TX %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% PRBS Generation
% 1) PRBS Generation
for i = 1:log2(M)
[bitpattern(:,i),seed] = prbs(O,N,seed);
end
% Build Inf. signal class
bits = Informationsignal(bitpattern);
% 2 ) Build Inf. signal class
bits = Informationsignal(bitpattern);
% Digi Mod
mod_out = digimod.map(bits);
% 3) Digi modulation -> PAM-M signal
digimod_out = digimod.map(bits);
% merken für EQ training
reference = mod_out;
% 4) Pulse shaping -> racos
X = pulseform.process(digimod_out);
% shape shape
X = pulseform.process(mod_out);
% 5) AWG (lowpass, quantization, sample and hold)
X = awg.process(X);
% AWG -> ELECTRICAL DOMAIN
X = awg.process(X);
% 6) Lowpass behavior of laser and hf-cable? why twice?
X = lp_laser.process(X);
X = lp_laser.process(X);
X = lp_laser.process(X);
X = lp_laser.process(X);
X = X.normalize("mode","oneone");
X.signal = X.signal .* 1.3800;
% Laser; Modulation -> OPTICAL DOMAIN
[X,extmodlaser] = extmodlaser.process(X);
% Fiber Propagation
X = fib.process(X);
%% Reflect with attenuation
R = reflectionpoint.process(X);
% Propagate back and forth
R = reflectionprop.process(R);
% 7) Normalize signal
X = X.normalize("mode","oneone");
X.signal = X.signal .* 1.3800;
% Delay
[R,n] = R.delay("delay_meter",delay);
%% D) PROCESS OPTICAL CHANNEL %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Add together
X.signal = X.signal(n:end);
R.signal = R.signal(n:end);
% 1) Laser; Modulation -> OPTICAL DOMAIN
[X,extmodlaser] = extmodlaser.process(X);
disp(['SIR ',num2str(10*log10(X.power/R.power))]);
% 2) Main fiber propagation
X = fib.process(X);
if delay ~= 0
% 3) Reflection
% Reflection is just an attenuation
R = reflectionpoint.process(X);
% Propagate back and forth (actual fiber propagation)
R = reflectionprop.process(R);
% Delay the reflected signal
[R,n] = R.delay("delay_meter",delay);
% % Add together
% col = cbrewer2('qual','Paired',8);
%
% xax = (1:X.length);% / fsimu * (physconst("LightSpeed")/1.4677);
% xax_mtr = (1:X.length) / fsimu * (physconst("LightSpeed")/1.4677);
% thresh = 0.7;
% phaseX = phase(X.signal);
% phaseR = phase(R.signal);
% phasediff = wrapToPi(phaseX-phaseR);
% [pos_high] = find(abs(phasediff)>thresh);
% [pos_low] = find(abs(phasediff)<=thresh);
%
% figure()
% subplot(3,1,1)
% scatter(xax_mtr,wrapToPi(phaseX),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','Phase of original Signal')
% hold on
% scatter(xax_mtr,wrapToPi(phaseR),4,'.','MarkerEdgeColor',col(7,:),'DisplayName','Phase of delayed Signal')
% hold on
% xline(delay,'LineWidth',4,'LineStyle','--','HandleVisibility','off')
% lg = legend;
% lg.Location = "southwest";
%
% subplot(3,1,2)
% scatter(xax_mtr(pos_low),phasediff(pos_low),4,'.','MarkerEdgeColor',col(6,:),'DisplayName','Phase Difference')
% hold on
% scatter(xax_mtr(pos_high),phasediff(pos_high),4,'.','MarkerEdgeColor',col(4,:),'HandleVisibility','off')
% xline(delay,'LineWidth',4,'LineStyle','--','HandleVisibility','off')
% yline(thresh,'LineWidth',2,'LineStyle','-','HandleVisibility','off')
% yline(-thresh,'LineWidth',2,'LineStyle','-','HandleVisibility','off')
% lg = legend;
% lg.Location = "southwest";
X = X+R;
% subplot(3,1,3)
% scatter(xax_mtr(pos_low),abs(X.signal(pos_low).^2),4,'.','MarkerEdgeColor',col(6,:),'DisplayName','Constructive Interference');
% hold on
% scatter(xax_mtr(pos_high),abs(X.signal(pos_high).^2),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','Destructive Interference');
% xline(delay,'LineWidth',4,'LineStyle','--','HandleVisibility','off')
%
% lg = legend;
% lg.Location = "southwest";
X.signal = X.signal(n:end);
R.signal = R.signal(n:end);
disp(['SIR ',num2str(10*log10(X.power/R.power))]);
% cut reference signal to correct length (nessecary due to MPI delay)
digimod_out.signal = digimod_out.signal(round(n * fsym/fsimu) : end,:);
bitpattern = bitpattern(round(n * fsym/fsimu):end,:);
end
X = X+R;
% plot(angle(R.signal))
% 4) Attenuation
X = opticatten.process(X);
%%
X = opticatten.process(X);
% X = edfaamp.process(X);
% 5) Photo Diode -> ELECTRICAL DOMAIN
X = phdiode.process(X);
X = lp_diode.process(X);
% Photo Diode -> ELECTRICAL DOMAIN
X = phdiode.process(X);
X = lp_diode.process(X);
% Oscilloscope (Sampling to f_adc; Quantization; Bandwidth Limitation)
X = scp.process(X);
%% E) PROCESS RX %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Resample to Symbol Rate
X = X.resample("fs_out",2*fsym,"fs_in",fadc);
% 1) Oscilloscope (Sampling to f_adc; Quantization; Bandwidth Limitation)
X = scp.process(X);
% Normalize
Eq_in = X.normalize("mode","rms");
% 2) Resample to 2x symbol rate
X = X.resample("fs_out",2*fsym,"fs_in",fadc);
% Equalizer
reference.signal = reference.signal(round(n * fsym/fsimu) : end,:);
% 3) Normalize
Eq_in = X.normalize("mode","rms");
tracking_speed_bandwidth = eq.FFEmu .* fsym .* 1e-9;
% 4) Equalize
%% MPI reduction DC removal BEFORE EQ
% wl = 1000; % symbols
% Eq_in.signal = Eq_in.signal - 1/wl .* movsum( Eq_in.signal,[wl/2,wl/2]);
% MPI reduction DC removal BEFORE EQ
wl = 3000; % symbols
Eq_in.signal = Eq_in.signal - 1/wl .* movsum( Eq_in.signal,[wl/2,wl/2]);
[Eq_out] = eq2.process(Eq_in,reference);
% Equalize Signal
[Eq_out] = eq2.process(Eq_in,digimod_out);
%% MPI reduction DC removal
%% A1: MPI reduction DC removal
wl = 1000; % symbols
yk_dcsm = Eq_out;
yk_dcsm.signal = Eq_out.signal - 1/wl .* movsum( Eq_out.signal,[wl/2,wl/2]);
%% MPI reduction Level wise error removal
%% A2: MPI reduction Level wise error removal
yk_lvsm = Eq_out;
yk_lvlp = Eq_out;
pre_decision_level_uni = digimod.decide_pamlevel(Eq_out);
@@ -183,7 +235,7 @@ for lp = 1
filtered = lp_mpi.process(e);
wl = 100; % symbols
wl = 30; % symbols
smoothed = ( 1/wl .* movsum(e,[wl/2,wl/2]) );
% remove interference
@@ -191,14 +243,8 @@ for lp = 1
yk_lvsm.signal(pre_decision_level_uni==level) = yk_lvsm.signal(pre_decision_level_uni==level) - smoothed(pre_decision_level_uni==level);
yk_lvlp.signal(pre_decision_level_uni==level) = yk_lvlp.signal(pre_decision_level_uni==level) - filtered(pre_decision_level_uni==level);
end
%
% figure(26);plot(1:length(error_log),error_log(:,end),"LineWidth",0.4);ylim([-0.8 0.8]);ylabel('$\epsilon$'),title(['Linewidth: ',num2str(laser_linewidth*1e-6), 'MHz'])
%
% figure(28);plot(1:length(e),e,"LineWidth",0.4);ylim([-0.8 0.8]);
%% Calc EVM
% Calc EVM
evm_bm = calc_evm(Eq_out.signal, pre_decision_level_bi);
evm_dcsm = calc_evm(yk_dcsm.signal, pre_decision_level_bi);
@@ -207,35 +253,35 @@ for lp = 1
% figure(1);bar([evm_bm' evm_dcsm' evm_llp' evm_lsm']);ylim([0.01 0.1]);set(gca,'yscale','log');
% Digi Demod
d_bm = digimod.demap(Eq_out);
d_dcsm = digimod.demap(yk_dcsm);
d_lvsm = digimod.demap(yk_lvsm);
d_lvlp = digimod.demap(yk_lvlp);
% BER
bitpattern = bitpattern(round(n * fsym/fsimu):end,:);
%% PROCESS RX %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 1) Digi Demod
d_bm = digimod.demap(Eq_out);
d_dcsm = digimod.demap(yk_dcsm);
d_lvsm = digimod.demap(yk_lvsm);
d_lvlp = digimod.demap(yk_lvlp);
% 2) BER
dbit = length(d_bm.signal)-length(bitpattern);
[~,errors_bm,ber_bm,loc] = calc_ber(d_bm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",1);
[~,errors_bm,ber_bm,loc] = calc_ber(d_bm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",1);
[~,errors_dcsm,ber_dcsm] = calc_ber(d_dcsm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",0);
[~,errors_lvsm,ber_lvsm] = calc_ber(d_lvsm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",0);
[~,errors_lvlp,ber_lvlp] = calc_ber(d_lvlp.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",0);
% Display
% Display BER
disp(['BER benchmark: ', sprintf('%2E',ber_bm), ' ERRORS: ' ,num2str(sum(errors_bm))]);
disp(['BER dc smooth (A1): ', sprintf('%2E',ber_dcsm), ' ERRORS: ' ,num2str(sum(errors_dcsm))]);
disp(['BER lv smooth (A2): ', sprintf('%2E',ber_lvsm), ' ERRORS: ' ,num2str(sum(errors_lvsm))]);
disp(['BER lv lowpas: ', sprintf('%2E',ber_lvlp), ' ERRORS: ' ,num2str(sum(errors_lvlp))]);
% disp(['BER dc smooth: ', sprintf('%2E',ber_dcsm), ' ERRORS: ' ,num2str(sum(errors_dcsm))]);
% disp(['BER lv smooth: ', sprintf('%2E',ber_lvsm), ' ERRORS: ' ,num2str(sum(errors_lvsm))]);
% disp(['BER lv lowpas: ', sprintf('%2E',ber_lvlp), ' ERRORS: ' ,num2str(sum(errors_lvlp))]);
%% Generate some Plots
if 1
% SCATTER
col = cbrewer2('Paired',8);
@@ -244,14 +290,16 @@ for lp = 1
figure(3)
sgtitle('')
subplot(1,2,1)
subplot(1,3,1)
hold on
eq_decision = digimod.decide_pamlevel(Eq_out);
true_symbols = digimod.decide_pamlevel(mod_out);
true_symbols = digimod.decide_pamlevel(digimod_out);
xindices = 1:Eq_in.length;
errorpos = find(loc~=0)*2;
errorpos(errorpos>length(Eq_in.signal)) = length(Eq_in.signal);
correct = find(loc==0)*2;
correct(correct>length(Eq_in.signal)) = length(Eq_in.signal);
scatter(xindices(correct),Eq_in.signal(correct),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','After EQ');
hold on
scatter(xindices(errorpos),Eq_in.signal(errorpos),6,'x','MarkerEdgeColor',col(6,:),'DisplayName','Wrong Decision');
@@ -264,7 +312,7 @@ for lp = 1
a = legend;
a.Location = "best";
subplot(1,2,2)
subplot(1,3,2)
xindices = 1:Eq_out.length;
scatter(xindices(loc==0),Eq_out.signal(loc==0),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','After EQ');
hold on
@@ -279,16 +327,31 @@ for lp = 1
a.Location = "best";
hold off
subplot(1,3,3)
xindices = 1:yk_lvsm.length;
scatter(xindices(loc==0),yk_lvsm.signal(loc==0),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','After A2');
hold on
scatter(xindices(loc~=0),yk_lvsm.signal(loc~=0),8,'x','MarkerEdgeColor',col(6,:),'DisplayName','Wrong Decision');
hold off
xlim([1, xax(end)]);
ylim([-2 2]);
xlabel('Sampling Index')
ylabel('Amplitude')
legend
a = legend;
a.Location = "best";
hold off
% ERROR IN EQ
figure(13)
plot(diff(eq2.error_log(1,:)));
plot((eq2.error_log(1,:)),'DisplayName','First iteration DD mode','Linewidth',0.5);
hold on;
for i = 1:size(eq2.error_log,1)
plot(diff(eq2.error_log(i,:)));
plot((eq2.error_log(i,:)),'Linewidth',0.5);
end
loc(loc==0) = NaN;
stem(loc.*mean((eq2.error_log(end,:))))
stem(loc.*mean((eq2.error_log(end,:))),'DisplayName','Error Positions')
hold off
end
@@ -301,7 +364,7 @@ for lp = 1
subplot(2,1,1)
hold on
plot(reference.signal(4150:4175),'DisplayName','Tx','Color',col(1,:),'LineWidth',3);
plot(digimod_out.signal(4150:4175),'DisplayName','Tx','Color',col(1,:),'LineWidth',3);
plot(Eq_out.signal(4150:4175),'DisplayName','Rx after EQ','Color',col(6,:),'LineWidth',1);
title('Modulated Sequence Zoom');
legend