%I can't make BER=0, I think, something is wrong with demodulation, in the demodulated sequence there are only numbers 5, 7, 13, 15. Now BER is equal to about half of all bit values, so what can I do to resolve this and make BER=0?
clc
close all
clear all
M = 16;
L=10000;
T=10;
W=43; %SNR
bits1 = randi([0 M-1], 1, L);
bits2 = randi([0 3], 1, L/T);
mod1 = qammod(bits1, M,'UnitAveragePower', true);
% scatterplot(mod1)
mod2 = qammod(bits2, 4, 'UnitAveragePower',true);
% scatterplot(mod2)
for i = 1:length(bits2)
sym(i,:)=[mod1((i-1)*T+1:i*T) mod2(i)];
end
f=0;
for k=1:L/T
for j=1:T+1
f=f+1;
symbols(f)=sym(k,j);
end
end
% scatterplot(symbols)
% symbols = awgn(symbols,W,"measured");
pnoise = comm.PhaseNoise('Level',[-70 -104 -110],'FrequencyOffset',[1e4 1e5 2e5], 'SampleRate', 28e6);
symbols2 = pnoise([zeros(1e5,1);symbols']);
% symbols2 = pnoise(symbols);
fc = 1e6; % Carrier frequency in Hz
fs = 28e6; % Sample rate in Hz.
phNzLevel = [-70 -104 -110]; % in dBc/Hz
phNzFreqOff = [1e4 1e5 2e5]; % in Hz
Nspf = 6e6; % Number of Samples per frame
freqSpan = 400e3; % in Hz, for spectrum computation
sinewave = dsp.SineWave( ...
Amplitude=1, ...
Frequency=fc, ...
SampleRate=fs, ...
SamplesPerFrame=Nspf, ...
ComplexOutput=true);
pnoise = comm.PhaseNoise( ...
Level=phNzLevel, ...
FrequencyOffset=phNzFreqOff, ...
SampleRate=fs);
sascopeRBW100 = spectrumAnalyzer( ...
SampleRate=fs, ...
Method="welch", ...
FrequencySpan="Span and center frequency", ...
CenterFrequency=fc, ...
Span=freqSpan, ...
RBWSource="Property", ...
RBW=100, ...
SpectrumType="Power density", ...
SpectralAverages=10, ...
SpectrumUnits="dBW", ...
YLimits=[-150 10], ...
Title="Resolution Bandwidth 100 Hz", ...
ChannelNames={'signal','signal with phase noise'}, ...
Position=[79 147 605 374]);
x = sinewave();
y = pnoise(x);
sascopeRBW100(x,y)
symbols2 = symbols2(1e5+1:end);
prim(1,:)=symbols2(1:T);
for i = 1:length(bits2)-1
prim(i+1,:)=symbols2(i*T+i+1:i*T+i+T);
end
for b = 1:length(mod2)
qam4(b)=symbols2((T+1)*b);
end
h=0;
for u=1:L/T
for l=1:T
h=h+1;
priem(h)=prim(u,l);
end
end
for g = 1:L/T
phase_error(g) = angle(qam4(g) / mod2(g));
compensated4(g) = qam4(g) .* exp(-1i * phase_error(g));
end
for v = 1:L/T
phase_errorM((v-1)*T+1:v*T)=phase_error(v);
end
for f = 1:L
compensatedM(f) = priem(f) .* exp(-1i*phase_errorM(f));
end
demod=qamdemod(compensatedM, M, 'bin','OutputType','bit');
% scatterplot(qam4)
% scatterplot(symbols2)
% scatterplot(compensatedM)
[number,ratio]=biterr(bits1,demod);
evm = lteEVM(demod,bits1);
figure('Position',[200 200 1080 540])
subplot(1,2,1)
scatter(real(symbols2),imag(symbols2),300,".")
subplot(1,2,2)
scatter(real(compensatedM),imag(compensatedM),300,".")
