%                        The University of Queensland
%     School of Information Technology & Electrical Engineering
%              COMS3100/7100 Introduction to Communications

% Plot SNR in dB from 0 dB to 20 dB in 0.1 dB steps
snrdb = 0:0.1:20;
snr = 10.^(snrdb / 10);

% The Q function is evaluated in Matlab using the normcdf function.  It's
% easy to show that Q(z) = normcdf(-z, 0, 1)
semilogy(snrdb, normcdf(-sqrt(snr/2), 0, 1));
ylim([1e-8, 1]);
xlabel('SNR (dB)');
ylabel('BER');
grid on;