Chromatic dispersion and line width phase noise

[4yp.git] / phasenoise1signal.m

numSymbs = 10000;
M = 4;

Rsym = 2.5e10; % symbol rate (sym/sec)
rolloff = 0.25;
span = 6; % filter span
sps = 4; % samples per symbol

fs = Rsym * sps; % sampling freq (Hz)
Tsamp = 1 / fs;

t = (0 : 1 / fs : numSymbs / Rsym + (1.5 * span * sps - 1) / fs)';


EbN0_db = 8;
EbN0 = 10 .^ (EbN0_db ./ 10);

Es = 1;
Eb = Es / log2(M);
N0 = Eb ./ EbN0;

EsN0 = EbN0 .* log2(M);
EsN0_db = 10 .* log10(EsN0);


data = randi([0 M - 1], numSymbs, 1);
modData = pskmod(data, M, 0, 'gray');

x = txFilter(modData, rolloff, span, sps);

linewidthTx = 0;%1e5; % Hz
linewidthLO = 1e6; % Hz
%%linewidthTx = Rsym * 1e-4; % Hz
%%linewidthLO = Rsym * 1e-3; % Hz

[xPN, pTxLO] = phaseNoise(x, linewidthTx, linewidthLO, Tsamp);

snr = EbN0_db + 10 * log10(log2(M)) - 10 * log10(sps);
noiseEnergy = 10 ^ (-snr / 10);

y = awgn(xPN, snr, 'measured');

r = rxFilter(y, rolloff, span, sps);

[rPhaseEq, phiests] = phaseNoiseCorr(r, M, 40 * sps);
rPhaseEq = normalizeEnergy(rPhaseEq, numSymbs, 1 + noiseEnergy);

rSampled = rPhaseEq(sps*span/2+1:sps:(numSymbs + span/2) * sps);
demodData = pskdemod(rSampled, M, 0, 'gray')';

[bitErrors, ber] = biterr(data, demodData)



figure(2);
plot(-phiests);
hold on;
plot(pTxLO);
legend('estimate', 'actual');
title('Phase noise estimation');
hold off;

figure(3);
plot(t(1:length(x)), real(x));
hold on;
plot(t, real(rPhaseEq), 'r');
%%sampledTimes = t(sps*span/2+1:sps:(numSymbs+span/2)*sps);
%%plot(sampledTimes, real(rSampled), 'x');
legend('original signal', 'corrected received signal');
title('Phase noise correction, linewidth 1 MHz, E_b/N_0=8 dB');
ylabel('Real part of signals');
axis([t(1) t(300) -Inf +Inf]);
hold off;
formatFigure;