400 lines
13 KiB
Matlab
400 lines
13 KiB
Matlab
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lw = [0.1e6 1e6 10e6];
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for lp = 1
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rng(9);
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%% A) Set Simulation Variables
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sir = -18;
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delay = 50; %mpi delay in meter
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fiblen = 0; %main link in km
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laser_linewidth =5e6;
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O = 19; %order of prbs
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N = 2^(O-1); %length of prbs
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[~,seed] = prbs(O,1); %initialize first seed of prbs
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% Modulation
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M = 4; %PAM-M
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bitpattern = zeros(N,log2(M));
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% Symbol Rate
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fsym = 112e9;
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% DAC Rate
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fdac = 120e9;
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% Simulation oversampling rate "k";
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kover = 16;
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% ADC Rate
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fadc = 256e9;
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% Simulation frequency in "analog domain"
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fsimu = kover * fdac ;
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%% B) CONSTRUCT ALL CLASSES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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digimod = PAMmapper(M,0);
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pulseform = Pulseformer("pulseform","rrc","fdac",fdac,"fsym",fsym,"pulselength",32,"rrcalpha",0.027);
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awg = AWG('fdac',fdac,'kover',kover,'lpf_active',1,'f_cutoff',56e9,'lpf_type',filtertypes.gaussian,'bit_resolution',5.5);
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lp_laser = Filter('filtdegree',1,"f_cutoff",50e9,"fsamp",fdac*kover,"filterType",filtertypes.bessel_inp);
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u_pi = 3.5;
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vbias = (0.5*u_pi)-u_pi;
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extmodlaser = EML("mode",eml_mode.im_cosinus,"power",5,"fsimu",fsimu,"lambda",1310,"bias",vbias,"u_pi",u_pi,"linewidth",laser_linewidth);
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fib = Fiber("fsimu",fdac*kover,"fiber_length",fiblen,"alpha",0.2,"D",16,"lambda0",thz2nm(193.1),"gamma",0);
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reflectionpoint = Amplifier("amp_mode","ideal_no_noise","gain_mode","gain","amplification_db",sir);
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reflectionprop = Fiber("fsimu",fdac*kover,"fiber_length",delay/1000,"alpha",0.2,"D",16,"lambda0",1550,"gamma",0);
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opticatten = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",-8);
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phdiode = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20);
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lp_diode = Filter('filtdegree',1,"f_cutoff",50e9,"fsamp",fdac*kover,"filterType",filtertypes.bessel_inp);
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scp = Scope("fsimu",fdac*kover,"fadc",fadc,...
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"delay",0,"fixed_delay",0,"lpf_bw",113e9,"filtertype",filtertypes.butterworth,...
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"samplingdelay",0,"rand_samplingdelay",0,"freq_offset",0,"samp_jitter",0,...
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"adcresolution",6,"quantbuffer",0.1,'block_dc',1);
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eq = EQ("K",2,"plottrain",0,"plotfinal",0,...
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"training_length",4096,"training_loops",2,...
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"Ne",[50,5,3],"Nb",[3,0,0],...
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"DCmu",0.05,"DDmu",[0.0004 0.0005 0.0006 0.0007 ],"DFEmu",0.005,"FFEmu",0.00,...
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"dd_loops",2,"epsilon",[10 100 1000 ],"M",2,...
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"thres",[0.005 0.004 0.0005 ],"l1act",0,"delay",0,"rho",0.0005,"ideal_dfe",0,"DB_aim",0);
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eq = EQ_silas("Ne",[50,5,3],"Nb",[2,0,0],"trainlength",4096,...
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"sps",2,...
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"mu_dc_dd",0.05,...
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"mu_dc_train",0.05,...
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"mu_ffe_train",0,...
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"mu_dfe_train",0.005,...
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"mu_ffe_dd",[0.0004 0.0004 0.0004],...
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"mu_dfe_dd",0.005,...
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"ddloops",3,...
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"trainloops",4,...
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"dcmode",1);
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%% C) PROCESS TX %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% 1) PRBS Generation
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for i = 1:log2(M)
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[bitpattern(:,i),seed] = prbs(O,N,seed);
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end
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% 2 ) Build Inf. signal class
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bits = Informationsignal(bitpattern);
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% 3) Digi modulation -> PAM-M signal
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digimod_out = digimod.map(bits);
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% 4) Pulse shaping -> racos
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X = pulseform.process(digimod_out);
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% 5) AWG (lowpass, quantization, sample and hold)
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X = awg.process(X);
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% 6) Lowpass behavior of laser and hf-cable? why twice?
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X = lp_laser.process(X);
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% X = lp_laser.process(X);
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% 7) Normalize signal
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X = X.normalize("mode","oneone");
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X.signal = X.signal .* 1.3800;
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%% D) PROCESS OPTICAL CHANNEL %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% 1) Laser; Modulation -> OPTICAL DOMAIN
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[X,extmodlaser] = extmodlaser.process(X);
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% 2) Main fiber propagation
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X = fib.process(X);
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if delay ~= 0
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% 3) Reflection
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% Reflection is just an attenuation
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R = reflectionpoint.process(X);
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% Propagate back and forth (actual fiber propagation)
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R = reflectionprop.process(R);
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% Delay the reflected signal
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[R,n] = R.delay("delay_meter",delay);
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% Add together
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col = cbrewer2('qual','Paired',8);
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xax = (1:X.length);% / fsimu * (physconst("LightSpeed")/1.4677);
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xax_sec = (1:X.length) / fsimu .* 1e6;%* (physconst("LightSpeed")/1.4677);
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xax_sec = xax_sec(n:end).';
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thresh = pi/4;
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phaseX = phase(X.signal(n:end));
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phaseR = phase(R.signal(n:end));
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phasediff = wrapToPi(phaseX-phaseR);
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[pos_high] = find(abs(phasediff)>thresh);
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[pos_low] = find(abs(phasediff)<=thresh);
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figure(6);hold on;histogram(phaseX-phaseR,500,'EdgeAlpha',0)
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figure()
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subplot(3,1,1)
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scatter(xax_sec.',wrapToPi(phaseX),4,'.','MarkerEdgeColor',col(2,:),'DisplayName','Desired Signal')
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hold on
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scatter(xax_sec,wrapToPi(phaseR),4,'.','MarkerEdgeColor',col(1,:),'DisplayName','Reflected Signal')
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hold on
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lg = legend;
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lg.Location = "southwest";
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xlim([xax_sec(1) xax_sec(end)]);
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xlabel('time in $\mu$s')
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ylim([-pi pi]);
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yticks([-pi 0 pi])
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yticklabels({'$-\pi$',0, '$\pi$'})
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ylabel('$\phi$')
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subplot(3,1,2)
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scatter(xax_sec(pos_low),phasediff(pos_low),4,'.','MarkerEdgeColor',col(5,:),'DisplayName','Phase Difference')
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hold on
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scatter(xax_sec(pos_high),phasediff(pos_high),4,'.','MarkerEdgeColor',col(2,:),'HandleVisibility','off')
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% yline(thresh,'LineWidth',2,'LineStyle','-','HandleVisibility','off')
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% yline(-thresh,'LineWidth',2,'LineStyle','-','HandleVisibility','off')
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lg = legend;
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lg.Location = "southwest";
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xlabel('time in $\mu$s')
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xlim([xax_sec(1) xax_sec(end)]);
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ylim([-pi pi]);
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yticks([-pi 0 pi])
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yticklabels({'$-\pi$',0, '$\pi$'})
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ylabel('$\Delta \phi$')
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X.signal = X.signal(n:end);
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R.signal = R.signal(n:end);
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X1 = X;
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X = X+R;
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subplot(3,1,3)
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scatter(xax_sec(pos_low),abs(X.signal(pos_low).^2)*1000,4,'.','MarkerEdgeColor',col(5,:),'DisplayName','Constructive Interference');
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hold on
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scatter(xax_sec(pos_high),abs(X.signal(pos_high).^2)*1000,4,'.','MarkerEdgeColor',col(2,:),'DisplayName','Destructive Interference');
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%scatter(xax_sec(pos_high),abs(X1.signal(pos_high).^2)*1000,4,'.','MarkerEdgeColor',col(1,:),'MarkerFaceAlpha',0.3,'DisplayName','Destructive Interference');
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xlim([xax_sec(1) xax_sec(end)]);
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xlabel('time in $\mu$s')
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lg = legend;
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lg.Location = "southwest";
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ylabel('Optical power in mW');
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disp(['SIR ',num2str(10*log10(X.power/R.power))]);
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% cut reference signal to correct length (nessecary due to MPI delay)
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digimod_out.signal = digimod_out.signal(round(n * fsym/fsimu) : end,:);
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bitpattern = bitpattern(round(n * fsym/fsimu):end,:);
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end
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% plot(angle(R.signal))
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% 4) Attenuation
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X = opticatten.process(X);
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% 5) Photo Diode -> ELECTRICAL DOMAIN
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X = phdiode.process(X);
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X = lp_diode.process(X);
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%% E) PROCESS RX %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% 1) Oscilloscope (Sampling to f_adc; Quantization; Bandwidth Limitation)
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X = scp.process(X);
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% 2) Resample to 2x symbol rate
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X = X.resample("fs_out",2*fsym,"fs_in",fadc);
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% 3) Normalize
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Eq_in = X.normalize("mode","rms");
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% 4) Equalize
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% MPI reduction DC removal BEFORE EQ
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wl = 3000; % symbols
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Eq_in.signal = Eq_in.signal - 1/wl .* movsum( Eq_in.signal,[wl/2,wl/2]);
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% Equalize Signal
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[Eq_out] = eq.process(Eq_in,digimod_out);
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%% A1: MPI reduction DC removal
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wl = 1000; % symbols
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yk_dcsm = Eq_out;
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yk_dcsm.signal = Eq_out.signal - 1/wl .* movsum( Eq_out.signal,[wl/2,wl/2]);
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%% A2: MPI reduction Level wise error removal
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yk_lvsm = Eq_out;
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yk_lvlp = Eq_out;
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pre_decision_level_uni = digimod.decide_pamlevel(Eq_out);
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pre_decision_level_bi = ( pre_decision_level_uni*2-3 ) .* 1/sqrt(5);
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e = Eq_out.signal - pre_decision_level_bi;
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lp_mpi = Filter('filtdegree',1,"f_cutoff",2e6,"fsamp",fsym,"filterType",filtertypes.bessel_inp);
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filtered = lp_mpi.process(e);
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wl = 30; % symbols
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smoothed = ( 1/wl .* movsum(e,[wl/2,wl/2]) );
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% remove interference
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for level = 0:3
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yk_lvsm.signal(pre_decision_level_uni==level) = yk_lvsm.signal(pre_decision_level_uni==level) - smoothed(pre_decision_level_uni==level);
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yk_lvlp.signal(pre_decision_level_uni==level) = yk_lvlp.signal(pre_decision_level_uni==level) - filtered(pre_decision_level_uni==level);
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end
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% Calc EVM
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evm_bm = calc_evm(Eq_out.signal, pre_decision_level_bi);
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evm_dcsm = calc_evm(yk_dcsm.signal, pre_decision_level_bi);
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evm_lsm = calc_evm(yk_lvsm.signal, pre_decision_level_bi);
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evm_llp = calc_evm(yk_lvlp.signal, pre_decision_level_bi);
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% figure(1);bar([evm_bm' evm_dcsm' evm_llp' evm_lsm']);ylim([0.01 0.1]);set(gca,'yscale','log');
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%% PROCESS RX %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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% 1) Digi Demod
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d_bm = digimod.demap(Eq_out);
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d_dcsm = digimod.demap(yk_dcsm);
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d_lvsm = digimod.demap(yk_lvsm);
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d_lvlp = digimod.demap(yk_lvlp);
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% 2) BER
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dbit = length(d_bm.signal)-length(bitpattern);
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[~,errors_bm,ber_bm,loc] = calc_ber(d_bm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",1);
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[~,errors_dcsm,ber_dcsm] = calc_ber(d_dcsm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",0);
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[~,errors_lvsm,ber_lvsm] = calc_ber(d_lvsm.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",0);
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[~,errors_lvlp,ber_lvlp] = calc_ber(d_lvlp.signal(1:end-dbit,:) ,bitpattern(1:end,:),"skip",0,"returnErrorLocation",0);
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% Display BER
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disp(['BER benchmark: ', sprintf('%2E',ber_bm), ' ERRORS: ' ,num2str(sum(errors_bm))]);
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disp(['BER dc smooth (A1): ', sprintf('%2E',ber_dcsm), ' ERRORS: ' ,num2str(sum(errors_dcsm))]);
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disp(['BER lv smooth (A2): ', sprintf('%2E',ber_lvsm), ' ERRORS: ' ,num2str(sum(errors_lvsm))]);
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disp(['BER lv lowpas: ', sprintf('%2E',ber_lvlp), ' ERRORS: ' ,num2str(sum(errors_lvlp))]);
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%% Generate some Plots
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if 1
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% SCATTER
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col = cbrewer2('Paired',8);
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xax = 1:Eq_out.length;
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figure(3)
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sgtitle('')
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subplot(1,3,1)
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hold on
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eq_decision = digimod.decide_pamlevel(Eq_out);
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true_symbols = digimod.decide_pamlevel(digimod_out);
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xindices = 1:Eq_in.length;
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errorpos = find(loc~=0)*2;
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errorpos(errorpos>length(Eq_in.signal)) = length(Eq_in.signal);
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correct = find(loc==0)*2;
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correct(correct>length(Eq_in.signal)) = length(Eq_in.signal);
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scatter(xindices(correct),Eq_in.signal(correct),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','After EQ');
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hold on
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scatter(xindices(errorpos),Eq_in.signal(errorpos),6,'x','MarkerEdgeColor',col(6,:),'DisplayName','Wrong Decision');
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hold off
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xlim([1, xindices(end)]);
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ylim([-3 3]);
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xlabel('Sampling Index')
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ylabel('Amplitude')
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a = legend;
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a.Location = "best";
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subplot(1,3,2)
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xindices = 1:Eq_out.length;
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xax_sec = (1:Eq_out.length) / fsym .* 1e6;
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scatter(xax_sec(loc==0),Eq_out.signal(loc==0),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','After EQ');
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hold on
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scatter(xindices(loc~=0),Eq_out.signal(loc~=0),8,'x','MarkerEdgeColor',col(6,:),'DisplayName','Wrong Decision');
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hold off
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xlim([1, xax(end)]);
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ylim([-2 2]);
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xlabel('Sampling Index')
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ylabel('Amplitude')
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legend
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a = legend;
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a.Location = "best";
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hold off
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subplot(1,3,3)
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xindices = 1:yk_lvsm.length;
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scatter(xindices(loc==0),yk_lvsm.signal(loc==0),4,'.','MarkerEdgeColor',col(4,:),'DisplayName','After A2');
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hold on
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scatter(xindices(loc~=0),yk_lvsm.signal(loc~=0),8,'x','MarkerEdgeColor',col(6,:),'DisplayName','Wrong Decision');
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hold off
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xlim([1, xax(end)]);
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ylim([-2 2]);
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xlabel('Sampling Index')
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ylabel('Amplitude')
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legend
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a = legend;
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a.Location = "best";
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hold off
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end
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if 0
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col = cbrewer2('Paired',8);
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figure(11)
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clf
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subplot(2,1,1)
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hold on
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plot(digimod_out.signal(4150:4175),'DisplayName','Tx','Color',col(1,:),'LineWidth',3);
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plot(Eq_out.signal(4150:4175),'DisplayName','Rx after EQ','Color',col(6,:),'LineWidth',1);
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title('Modulated Sequence Zoom');
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legend
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hold off
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subplot(2,1,2)
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hold on
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stem(d_bm.signal(4150:4175,1),'DisplayName','Tx','Color',col(1,:),'LineStyle','-','LineWidth',5)
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stem(bitpattern(4150:4175,1)','DisplayName','Rx','Color',col(6,:),'LineStyle','--','LineWidth',2)
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title('Bitpattern Tx - Rx');
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legend
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hold off
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end
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end
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