%% Plot Noisy QPSK Constellation with Reference Symbols
% Fine reference symbols for a quadrature phase-shift keying (QPSK) modulation scheme and plot the resulting constellation.
% Generate noisy QPSK symbols.

sym =  awgn(qammod(randi([0 3],100,1),4)/sqrt(2),20);

% Find the reference symbols.

refSym =  wlanReferenceSymbols('QPSK');

% Plot the constellation diagram.

figure;
plot(sym,'b.');
hold on;
plot(refSym,'ro');
title('Noisy QPSK Constellation with Reference Symbols');
legend('Noisy symbols','Reference symbols','Location','South');

% Copyright 2018 The MathWorks, Inc.