238 lines
9.4 KiB
Matlab
238 lines
9.4 KiB
Matlab
%%% Run parameters
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% TX
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M = 6;
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fsym = 112e9;
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apply_pulsef = 1;
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fdac = 256e9;
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fadc = 256e9;
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random_key = 2;
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rcalpha = 0.05;
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kover = 16;
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vbias_rel = 0.5;
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u_pi = 2.9;
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vbias = -vbias_rel*u_pi;
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laser_wavelength = 1290;
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laser_linewidth = 0;
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% Channel
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link_length = 10000;
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vnle_order1 = 50;
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vnle_order2 = 3;
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vnle_order3 = 3;
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vnle_order=[vnle_order1,vnle_order2,vnle_order3];
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dfe_order = [0 0 0];
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alpha = 0;
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len_tr = 4096*2;
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mu_ffe1 = 0.0001;
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mu_ffe2 = 0.0008;
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mu_ffe3 = 0.001;
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mu_dc = 0.005;
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% mu_dc = 0;
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mu_ffe = [mu_ffe1 mu_ffe3 mu_ffe3];
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mu_dfe = 0.0004;
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dfe_ = sum(dfe_order)>0;
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doub_mode = db_mode.no_db;
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rop = [-5];
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bwl = [0.5:0.1:1.5];
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fsym = [72:8:170].*1e9;
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ber_vnle = [];
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ber_mlse = [];
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ber_viterbi = [];
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ber_db = [];
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ber_db_diff_precoded = [];
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gmi_vnle = [];
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gmi_mlse = [];
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gmi_mlse_db = [];
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parfor r = 1:length(fsym)
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Pform = Pulseformer("fsym",fsym(r),"fdac",4*fsym(r),"pulse","rc","pulselength",16,"alpha",rcalpha);
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db_precode = 0;
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db_encode = 0;
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duob_mode = db_mode.no_db;
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apply_pulsef = 1;
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[Digi_sig,Symbols,Tx_bits] = PAMsource(...
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"fsym",fsym(r),"M",M,"order",18,"useprbs",0,...
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"fs_out",fdac,...
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"applyclipping",0,"clipfactor",1.5,...
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"applypulseform",apply_pulsef,"pulseformer",Pform,...
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"randkey",random_key,...
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"db_precode",db_precode,"db_encode",db_encode,...
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"mrds_code",0,"mrds_blocklength",512,"duobinary_mode",duob_mode).process();
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El_sig = AWG("fdac",fdac,"f_cutoff",fsym(r),"lpf_active",0,"kover",kover,"bit_resolution",12,"upsampling_method","samplehold","precomp_sinc_rolloff",0).process(Digi_sig);
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%%%%% Low-pass el. components %%%%%%
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tx_bwl = 50e9;
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El_sig = Filter('filtdegree',4,"f_cutoff",tx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(El_sig);
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%%%%% Electrical Driver Amplifier %%%%%%
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El_sig = El_sig.normalize("mode","oneone");
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%%%%% MODULATE E/O CONVERSION %%%%%%
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[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).process(El_sig);
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%%%%%% Fiber %%%%%%
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Opt_sig = Fiber("fsimu",Opt_sig.fs,"fiber_length",link_length/1000,"alpha",0.3,"D",0,"lambda0",1310,"gamma",0,"Dslope",0.07).process(Opt_sig);
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%%%%%% ROP %%%%%%
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Opt_sig = Amplifier("amp_mode","ideal_no_noise","gain_mode","output_power","amplification_db",rop).process(Opt_sig);
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%%%%%% PD Square Law %%%%%%
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PD_sig = Photodiode("fsimu",fdac*kover,"dark_current",2e-08,"responsivity",1,"temperature",20,"nep",1.8e-11,"randomkey",random_key).process(Opt_sig);
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%%%%%% Low-pass RX (PD, El. Connectors and Scope %%%%%%
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rx_bwl = 50e9;
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PD_sig = Filter('filtdegree',4,"f_cutoff",rx_bwl,"fs",fdac*kover,"filterType",filtertypes.butterworth,"active",true).process(PD_sig);
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% %%%%%% Low-pass Scope %%%%%%
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Lp_scpe = Filter('filtdegree',4,"f_cutoff",110e9,"fs",fadc,"filterType",filtertypes.butterworth,"active",true);
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%%%%%% Scope %%%%%%
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Scpe_sig = Scope("fsimu",fdac*kover,"fadc",fadc,...
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"delay",0,"fixed_delay",0,"filtertype",filtertypes.butterworth,...
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"samplingdelay",0,"rand_samplingdelay",0,"freq_offset",0,"samp_jitter",0,...
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"adcresolution",8,"quantbuffer",0.1,'block_dc',1,'lpf_active',1,'H_lpf',Lp_scpe).process(PD_sig);
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Scpe_sig_2sps = Scpe_sig.resample("fs_out",2*fsym(r));
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% Scpe_sig_resampled.signal = Scpe_sig_resampled.signal(1:2*length(Symbols));
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[~, Scpe_cell, ~, found_sync] = Scpe_sig_2sps.tsynch("reference", Symbols, "fs_ref", fsym(r), "debug_plots", 0);
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Rx_sig = Scpe_cell{1};
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if 1
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%Duobinary Targeting
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eq_ = EQ("Ne",[vnle_order1,vnle_order2,vnle_order3],"Nb",[dfe_order],"training_length",len_tr,"training_loops",5,"dd_loops",5,"K",2,"DCmu",mu_dc,"DDmu",[mu_ffe mu_dfe],"DFEmu",0.005,"FFEmu",0,"plotfinal",0,"ideal_dfe",1);
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mlse_ = MLSE("DIR",[1,1],"duobinary_output",0,"M",M,"trellis_states",PAMmapper(M,0).levels);
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db_ref_sequence = Duobinary().encode(Symbols);
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db_ref_constellation = unique(db_ref_sequence.signal);
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[eq_signal, eq_noise] = eq_.process(Rx_sig,db_ref_sequence);
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mlse_.DIR = [1,1];
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[mlse_sig_sd,LLR,gmi_mlse_db(r)] = mlse_.process(eq_signal,Symbols);
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mlse_sig_hd = PAMmapper(M,0,"eth_style",0).quantize(mlse_sig_sd);
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mlse_sig_hd_precoded = Duobinary().encode(mlse_sig_hd,"M",M);
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mlse_sig_hd_precoded = Duobinary().decode(mlse_sig_hd_precoded,"M",M);
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tx_symbols_precoded = Duobinary().encode(Symbols);
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tx_symbols_precoded = Duobinary().decode(tx_symbols_precoded);
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tx_bits_precoded = PAMmapper(M,0,"eth_style",0).demap(tx_symbols_precoded);
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rx_bits_mlse = PAMmapper(M,0,"eth_style",0).demap(mlse_sig_hd_precoded);
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[~,errors_db_diff_precoded,ber_db_diff_precoded(r),~] = calc_ber(rx_bits_mlse.signal,tx_bits_precoded.signal,"skip_front",100,"skip_end",150,"returnErrorLocation",1);
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%B) Just determine BER
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rx_bits_mlse = PAMmapper(M,0,"eth_style",0).demap(mlse_sig_hd);
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[bits_mlse,errors_mlse,ber_db(r),~] = calc_ber(rx_bits_mlse.signal,Tx_bits.signal,"skip_front",100,"skip_end",150,"returnErrorLocation",1);
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end
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% FFE or VNLE
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eq_ = EQ("Ne",[vnle_order1,vnle_order2,vnle_order3],"Nb",[dfe_order],"training_length",len_tr,"training_loops",5,"dd_loops",5,"K",2,"DCmu",mu_dc,"DDmu",[mu_ffe mu_dfe],"DFEmu",0.005,"FFEmu",0,"plotfinal",0,"ideal_dfe",1);
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[eq_signal_sd, eq_noise] = eq_.process(Rx_sig, Symbols);
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[gmi_gomez(r)] = calc_air(eq_signal_sd, Symbols, "skip_front", 100, "skip_end", 100);
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[gmi_vnle(r)] = calc_ngmi(eq_signal_sd,Symbols);
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[gmi_bitwise(r)] = calc_gmi_bitwise(eq_signal_sd,Symbols);
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snr_vnle(r) = calc_snr(Symbols, eq_signal_sd-Symbols);
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eq_signal_sd.plot("displayname",'bla','fignum',118);
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% Hard decision on VNLE output
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eq_signal_hd = PAMmapper(M, 0).quantize(eq_signal_sd);
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rx_bits = PAMmapper(M,0,"eth_style",0).demap(eq_signal_hd);
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[~,~,ber_vnle(r),~] = calc_ber(rx_bits.signal,Tx_bits.signal,"skip_front",100,"skip_end",150,"returnErrorLocation",1);
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fprintf('BER VNLE: %.2e \n',ber_vnle(r));
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fprintf('NGMI VNLE: %.2f \n',gmi_vnle(r)./log2(M));
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if 1
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% Process through postfilter and MLSE
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pf_ncoeffs = 1;
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pf_ = Postfilter("ncoeff",pf_ncoeffs,"useBurg",1);
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mlse_ = MLSE("duobinary_output",0,'M',M,'trellis_states',PAMmapper(M,0).levels);
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[mlse_sig_sd,whitened_noise] = pf_.process(eq_signal_sd, eq_noise);
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mlse_.DIR = pf_.coefficients;
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alpha(r) = pf_.coefficients(2);
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[signalclass_hd,LLR,gmi_mlse(r)] = mlse_.process(mlse_sig_sd,Symbols);
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mlse_sig_hd = PAMmapper(M, 0, "eth_style", 0).quantize(signalclass_hd);
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rx_bits = PAMmapper(M,0,"eth_style",0).demap(mlse_sig_hd);
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[~,~,ber_mlse(r),~] = calc_ber(rx_bits.signal,Tx_bits.signal,"skip_front",100,"skip_end",150,"returnErrorLocation",1);
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fprintf('BER: %.2e \n',ber_mlse(r));
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fprintf('GMI MLSE: %.5f \n',gmi_mlse(r));
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% Process through postfilter and MLSE
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pf_ncoeffs = 1;
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pf_ = Postfilter("ncoeff",pf_ncoeffs,"useBurg",1);
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mlse_ = MLSE_viterbi("duobinary_output",0,'M',M,'trellis_states',PAMmapper(M,0).levels);
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[mlse_sig_sd,whitened_noise] = pf_.process(eq_signal_sd, eq_noise);
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mlse_.DIR = pf_.coefficients;
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mlse_sig_sd = mlse_.process(mlse_sig_sd);
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mlse_sig_hd = PAMmapper(M, 0, "eth_style", 0).quantize(mlse_sig_sd);
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rx_bits = PAMmapper(M,0,"eth_style",0).demap(mlse_sig_hd);
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[~,~,ber_viterbi(r),~] = calc_ber(rx_bits.signal,Tx_bits.signal,"skip_front",100,"skip_end",150,"returnErrorLocation",1);
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fprintf('Viterbi BER: %.2e \n',ber_viterbi(r));
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end
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end
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cols = cbrewer2('Paired',8);
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d = 1;
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figure(11);hold on
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plot(fsym.*1e-9,alpha,'DisplayName','VNLE','Marker','x','LineStyle','-','Color',cols(1+d,:));
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xlabel('Baudrate in GBd');
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ylabel('alpha');
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figure(15);hold on
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plot(fsym.*1e-9,gmi_gomez,'DisplayName','gomez','Marker','x','LineStyle','-','Color',cols(1+d,:));
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plot(fsym.*1e-9,gmi_vnle,'DisplayName','vnle other','Marker','x','LineStyle','-','Color',cols(3+d,:));
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% plot(fsym.*1e-9,gmi_bitwise,'DisplayName','bitwise','Marker','x','LineStyle','--','Color',cols(5+d,:));
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plot(fsym.*1e-9,gmi_mlse,'DisplayName','MLSE','Marker','*');
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plot(fsym.*1e-9,gmi_mlse_db,'DisplayName','DB Output','Marker','*');
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ylim([log2(M)-1 log2(M)]);
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xlabel('Baudrate in GBd');
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ylabel('GMI');
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figure(13);hold on
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plot(fsym.*1e-9,ber_vnle,'DisplayName','VNLE','Marker','x','LineStyle','-','Color',cols(1+d,:));
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plot(fsym.*1e-9,ber_mlse,'DisplayName','MLSE','Marker','x','LineStyle','-','Color',cols(3+d,:));
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plot(fsym.*1e-9,ber_viterbi,'DisplayName','Viterbi','Marker','x','LineStyle','--','Color',cols(5+d,:));
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plot(fsym.*1e-9,ber_db_diff_precoded,'DisplayName','MLSE db diff','Marker','.','MarkerSize',15,'LineStyle','-');
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plot(fsym.*1e-9,ber_db,'DisplayName','MLSE db','Marker','.','MarkerSize',15,'LineStyle','-');
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xlabel('Baudrate in GBd');
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ylabel('BER');
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set(gca, 'yscale', 'log');
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% ylim([1e-6 0.1]);
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legend
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% Auxiliary nested helper for numerically stable log-sum-exp
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function s = logsumexp(a)
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% LOGSUMEXP Compute log(sum(exp(a))) in a numerically stable way
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m = max(a);
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s = m + log(sum(exp(a - m)));
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end
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