%
%
% Analysis of the symbol error probability for M-PAM and
% M-PPM signals
%
% The function computes and plots the symbol error
% probability for M-PAM and M-PPM signals
% for M = {2, 4, 8} as a function of Eb/N0
% 
% Programmed by Luca De Nardis


% --------------------------
% Step Zero - Initialization
% --------------------------

Eb_N0 = logspace(0.5,2);      % Range of Eb/N0: 5-20 dB
M = [2 4 8];                  % Values of M

% -------------------------------------------------
% Step One - Evaluation of symbol error probability
% -------------------------------------------------

for i=1:3
    M_PAM(i,:)=(1-1/M(i))*erfc(sqrt(Eb_N0 * 3 *...
       log2(M(i))/(M(i)^2-1)));
    M_PPM(i,:)= exp(-0.5 * log2(M(i))*(Eb_N0 - 2 *...
       log(2)));
end

% ---------------------------
% Step Two - Graphical output
% ---------------------------

M_ary_BEP = [M_PAM' M_PPM']'  % Building a single matrix
                              % for all vectors
F=figure(1);
set(F,'Position',[100 190 650 450]);
set(gcf,'DefaultAxesColorOrder',[0 0 0],...
   'DefaultAxesLineStyleOrder','-+|-o|-*|:s|:d|:^');
PT=semilogy(10*log10(Eb_N0),M_ary_BEP);
set(PT,'LineWidth',[2]);
hold on
L= legend('2-PAM','4-PAM','8-PAM','2-PPM','4-PPM','8-PPM');
set(L,'FontSize',12);
set(PT,'LineWidth',[2]);
X=xlabel('E_b/N_0');
set(X,'FontSize',14);
Y=ylabel('Pr_e');
set(Y,'FontSize',14);
AX=gca;
set(AX,'FontSize',12);
axis([5 20 1e-6 1e-1]);
set(AX,'XTick', [5 7.5 10 12.5 15 17.5 20 ]);
grid on