4 Rsym = 2.5e10; % symbol rate (sym/sec)
6 span = 6; % Tx/Rx filter span
7 rolloff = 0.25; % Tx/Rx RRC rolloff
8 sps = 4; % samples per symbol
10 fs = Rsym * sps; % sampling freq (Hz)
13 t = (0 : 1 / fs : numSymbs / Rsym + (1.5 * span * sps - 1) / fs).';
15 data = randi([0 M - 1], numSymbs, 1);
16 modData = pskmod(data, M, pi / M, 'gray');
17 x = txFilter(modData, rolloff, span, sps);
19 %% Simulate chromatic dispersion
20 D = 17; % ps / (nm km)
24 [xCD, xCDkstart] = chromaticDispersion(x, D, lambda, z, Tsamp);
25 xCD = normalizeEnergy(xCD, numSymbs, 1);
28 snr = EbN0_db + 10 * log10(log2(M)) - 10 * log10(sps);
29 noiseEnergy = 10 ^ (-snr / 10);
31 %%y = awgn(xCD, snr, 'measured');
34 yCDComp = CDCompensation(y, D, lambda, z, Tsamp);
37 r = rxFilter(yCDComp, rolloff, span, sps);
38 rSampled = r(sps*span/2+1:sps:(numSymbs + span/2) * sps);
40 %% if no CD comp, then rotate constellation. Use:
42 theta = angle(-sum(rSampled .^ M)) / M;
43 %% if theta approx +pi/M, wrap to -pi/M
44 if abs(theta - pi / M) / (pi / M) < 0.1
47 rSampled = rSampled .* exp(-j * theta);
50 rAdaptEq = adaptiveCMA(rSampled);
52 %% Compare original signal and compensated signal
55 tsym = t(sps*span/2+1:sps:(numSymbs+span/2)*sps);
57 plot(t(1:length(x)), real(normalizeEnergy(x, numSymbs*sps, 1)), 'b');
59 plot(t(1:length(x)), real(normalizeEnergy(yCDComp(1:length(x)), numSymbs*sps, 1)), 'r');
60 plot(tsym, real(rAdaptEq), 'xg');
63 legend('original', 'dispersion compensated', 'CMA equalized samples');
64 axis([t(6000*sps+1) t(6000*sps+150) -Inf +Inf]);
66 plot(t(1:length(x)), imag(normalizeEnergy(x, numSymbs*sps, 1)), 'b');
68 plot(t(1:length(x)), imag(normalizeEnergy(yCDComp(1:length(x)), numSymbs*sps, 1)), 'r');
69 plot(tsym, imag(rAdaptEq), 'xg');
72 axis([t(6000*sps+1) t(6000*sps+150) -Inf +Inf]);
75 title('Constellation of original modulation');
76 scatterplot(rSampled);
77 title('Constellation of matched filter output');
78 scatterplot(rAdaptEq);
79 title('Constellation of adaptive filter output');
81 demodData = pskdemod(rSampled, M, pi / M, 'gray');
82 demodAdapt = pskdemod(rAdaptEq, M, pi / M, 'gray');
84 [~, ber] = biterr(data, demodData)
85 [~, ber] = biterr(data, demodAdapt)