4 Rsym = 2.5e10; % symbol rate (sym/sec)
7 span = 6; % filter span
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)';
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);
29 data = randi([0 M - 1], numSymbs, 1);
30 modData = pskmod(data, M, 0, 'gray');
31 x = txFilter(modData, rolloff, span, sps);
33 %% Simulate chromatic dispersion
34 D = 20; % ps / (nm km)
38 xCD = chromaticDispersion(x, D, lambda, z, Tsamp);
39 xCD = normalizeEnergy(xCD, numSymbs, 1);
43 snr = EbN0_db(i) + 10 * log10(log2(M)) - 10 * log10(sps);
44 noiseEnergy = 10 ^ (-snr / 10);
46 y = awgn(xCD, snr, 'measured');
48 yCDComp = CDCompensation(y, D, lambda, z, Tsamp);
50 r = rxFilter(yCDComp, rolloff, span, sps);
52 %r = normalizeEnergy(r, numSymbs, 1 + noiseEnergy);
54 rSampled = r(sps*span/2+1:sps:(numSymbs + span/2) * sps);
55 demodData = pskdemod(rSampled, M, 0, 'gray');
57 [bitErrors, ber(i)] = biterr(data, demodData);
63 %% Plot simulated results
64 semilogy(EbN0_db, ber, 'r', 'LineWidth', 2);
67 theoreticalPSK(EbN0_db, M, 'b', 'LineWidth', 1);
68 legend({'CD + AWGN + CD compensation', 'AWGN only'}, 'Location', 'southwest');
70 title(strcat(num2str(M), '-PSK with chromatic dispersion and compensation'));
72 xlabel('$E_b/N_0$ (dB)');