%-----------------------------------------------------------------------
% Plot of AWGN performance and diversity
%-----------------------------------------------------------------------

EbNodB = [0:0.5:30];
EbNo   = 10 .^(EbNodB/10);

%--- AWGN performance ----
Pawgn = 0.5*erfc(sqrt(EbNo));
semilogy(EbNodB,Pawgn);

%--- No Diversity  ----
mu = sqrt(EbNo ./ (1+EbNo));
L=1; b=0;
for k=0:L-1
    b = b + combinat(L-1+k,k) * ((1+mu)/2).^k;
end
Pray   = ((1-mu)/2).^L .* b ;

%--- Diversity 2 ----
L=2; b=0;
for k=0:L-1
    b = b + combinat(L-1+k,k) * ((1+mu)/2).^k;
end
PrayL2  = ((1-mu)/2).^L .* b ;

%--- Diversity 3 ----
L=3; b=0;
for k=0:L-1
    b = b + combinat(L-1+k,k) * ((1+mu)/2).^k;
end
PrayL3 = ((1-mu)/2).^L .* b ;

%--- Diversity 4 ----
L=4; b=0;
for k=0:L-1
    b = b + combinat(L-1+k,k) * ((1+mu)/2).^k;
end
PrayL4 = ((1-mu)/2).^L .* b ;

hold on
semilogy(EbNodB,Pray);
semilogy(EbNodB,PrayL2);
semilogy(EbNodB,PrayL3);
semilogy(EbNodB,PrayL4);
hold off
grid on
xlabel('Eb/No (dB)')
ylabel('Bit Error Rate')
axis([0 30 1E-6 1])

Temp = [EbNodB' Pray' PrayL2' PrayL3' PrayL4' Pawgn']