p1.m

A function to find necessary angle

clc
clear all
M = 16; % Size of signal constellation
k = log2(M); % Number of bits per symbol
n = 3e4; % Number of bits to process
nsamp = 1; % Oversampling rate
x = randint(n,1);
% Plot first 40 bits in a stem plot.
stem(x(1:40),'filled');
title('Random Bits');
xlabel('Bit Index'); ylabel('Binary Value');
%% Bit-to-Symbol Mapping
% Convert the bits in x into k-bit symbols.
xsym = bi2de(reshape(x,k,length(x)/k).','left-msb');

%% Stem Plot of Symbols 
% Plot first 10 symbols in a stem plot.
figure; % Create new figure window.
stem(xsym(1:10));
title('Random Symbols');
xlabel('Symbol Index'); ylabel('Integer Value');
%% Modulation
y = modulate(modem.qammod(M),xsym); % Modulate using 16-QAM.
%% Transmitted Signal
ytx = y;

%% Channel
% Send signal over an AWGN channel.
for i=0:30
snr = i;
ynoisy = awgn(ytx,snr,'measured');

%% Received Signal
yrx = ynoisy;

%% Scatter Plot
% Create scatter plot of noisy signal and transmitted
% signal on the same axes.
h = scatterplot(yrx(1:nsamp*5e3),nsamp,0,'g.');
hold on;
%scatterplot(ytx(1:5e3),1,0,'k*',h);
title('Received Signal');
legend('Received Signal','Signal Constellation');
axis([-5 5 -5 5]); % Set axis ranges.
hold off;
%% Demodulation
% Demodulate signal using 16-QAM.
zsym = demodulate(modem.qamdemod(M),yrx);
%% Symbol-to-Bit Mapping
% Undo the bit-to-symbol mapping performed earlier.
z = de2bi(zsym,'left-msb'); % Convert integers to bits.
% Convert z from a matrix to a vector.
z = reshape(z.',prod(size(z)),1);
%% BER Computation
% Compare x and z to obtain the number of errors and
% the bit error rate.
[number_of_errors(i),bit_error_rate(i)] = biterr(x,z)
end
plot(bit_error_rate,i);