4 Rsym = 2.5e10; % symbol rate (sym/sec)
7 span = 6; % filter span
8 sps = 8; % samples per symbol
10 fs = Rsym * sps; % sampling freq (Hz)
13 t = (0 : 1 / fs : numSymbs / Rsym + (1.5 * span * sps - 1) / fs).';
16 EbN0 = 10 .^ (EbN0_db ./ 10);
22 EsN0 = EbN0 .* log2(M);
23 EsN0_db = 10 .* log10(EsN0);
25 plotlen = length(EbN0);
27 ber = zeros(1, plotlen);
28 berNoComp = zeros(1, plotlen);
29 berAdapt = zeros(1, plotlen);
30 berMatlabAdapt = zeros(1, plotlen);
32 data = randi([0 M - 1], numSymbs, 1);
33 modData = pskmod(data, M, pi / M, 'gray');
34 x = txFilter(modData, rolloff, span, sps);
36 %% Simulate chromatic dispersion
37 D = 17; % ps / (nm km)
42 [xCD, xCDkstart] = chromaticDispersion(x, D, lambda, z, Tsamp);
49 snr = EbN0_db(i) + 10 * log10(log2(M)) - 10 * log10(sps);
51 y = awgn(xCD, snr, 'measured');
53 r = rxFilter(y, rolloff, span, sps);
56 Tsamp = TsampOrig * 4;
58 [rCDComp, CDCompkstart] = CDCompensation(r, D, lambda, z, Tsamp);
59 rCDComp = normalizeEnergy(rCDComp, numSymbs*sps, 1);
61 rSampled = rCDComp(2:2:end);
62 rNoCompSampled = r(2:2:end);
64 %% rotate rNoCompSampled to match original data
65 theta = angle(-sum(rNoCompSampled .^ M)) / M;
66 %% if theta approx +pi/M, wrap to -pi/M
67 if abs(theta - pi / M) / (pi / M) < 0.1
70 rNoCompSampled = rNoCompSampled .* exp(-j * theta);
73 %% Not entirely sure why, but after using FFT instead of time-domain
74 %% convolution for simulating CD, we now need to do the same rotation
75 %% for rSampled as well, but this time with a positive rotation.
76 theta = angle(-sum(rSampled .^ M)) / M;
77 if abs(theta + pi / M) / (pi / M) < 0.1
80 rSampled = rSampled .* exp(-1j * theta);
85 adaptFilterOut = adaptiveCMA(rSampled);
87 demodData = pskdemod(rSampled, M, pi / M, 'gray');
88 demodNoComp = pskdemod(rNoCompSampled, M, pi / M, 'gray');
89 demodAdapt = pskdemod(adaptFilterOut, M, pi / M, 'gray');
90 %%demodMatlabAdapt = pskdemod(matlabEq, M, pi / M, 'gray');
92 [bitErrors, ber(i)] = biterr(data, demodData);
93 [bitErrors, berNoComp(i)] = biterr(data, demodNoComp);
94 [~, berAdapt(i)] = biterr(data, demodAdapt);
95 %%[~, berMatlabAdapt(i)] = biterr(data, demodMatlabAdapt);
100 scatterplot(normalizeEnergy(rSampled, numSymbs, 1));
102 title('Constellation after CD comp.', 'interpreter', 'latex');
103 xlabel('In-Phase', 'interpreter', 'latex');
104 ylabel('Quadrature', 'interpreter', 'latex');
105 set(gca, 'FontSize', 18);
106 %%scatterplot(modData);
107 %%title('Original constellation');
108 scatterplot(normalizeEnergy(rNoCompSampled, numSymbs, 1));
110 title('Constellation without CD comp.', 'interpreter', 'latex');
111 xlabel('In-Phase', 'interpreter', 'latex');
112 ylabel('Quadrature', 'interpreter', 'latex');
113 set(gca, 'FontSize', 18);
114 %scatterplot(adaptFilterOut);
115 %title('Constellation with CD compensation and adaptive filter');
116 %scatterplot(matlabEq);
117 %title('Matlab equalizer');
129 %% Plot simulated results
130 semilogy(EbN0_db, ber, 'r', 'LineWidth', 2);
132 semilogy(EbN0_db, berNoComp, 'm', 'LineWidth', 2);
133 semilogy(EbN0_db, berAdapt, 'Color', [0, 0.6, 0], 'LineWidth', 2);
134 %%%semilogy(EbN0_db, berMatlabAdapt, 'c', 'LineWidth', 1.4);
136 theoreticalPSK(EbN0_db, M, 'b', 'LineWidth', 1);
137 %%legend({'CD + AWGN + CD comp.', 'CD + AWGN + CD comp.~+ CMA', ...
138 %% 'Theoretical AWGN'}, 'Location', 'southwest');
139 %%legend({'CD + AWGN + CD comp.', 'CD + AWGN', 'Theoretical AWGN'}, ...
140 %% 'Location', 'southwest');
141 legend({'CD + AWGN + CD comp.', 'CD + AWGN', ...
142 'CD + AWGN + CD comp.~+ CMA', 'Theoretical AWGN'}, 'Location', ...
145 %%title(strcat(num2str(M), '-PSK with chromatic dispersion and compensation'));
146 title({'QPSK with chromatic dispersion and compensation', ...
147 strcat(['$D = 17$ ps/(nm km), $z = ', num2str(z), '$ km'])});
149 xlabel('$E_b/N_0$ (dB)');