comp_exam10_1.m

the source code of Ziemer s book Digital communication. This code is related to the exercise part.

n = 7; k = 4; t = 1;					% code parameters
zdB = 0:0.1:14;						% set STw/No in dB
z = 10.^(zdB/10);						% STw/No
lenz = length(z);						% length of vector
qc = qfn(sqrt(2*z/n));					% coded symbol error prob.
qu = qfn(sqrt(2*z/k));					% uncoded symbol error prob.
peu = 1-((1-qu).^k);					% uncoded word error prob.
pec = zeros(1,lenz);					% initialize
for j=1:lenz
pc = qc(j);								% jth symbol error prob.
s = 0;									% initialize
for i=(t+1):n
   a = sum(log(1:n));				% ln of n!
	b = sum(log(1:i));				% ln of k!
	c = sum(log(1:(n-i)));			% ln of (n-k)!
   nchoosek = round(exp(a-b-c));	% n!/k!/(n-k)!
   termi = (pc^i)*((1-pc)^(n-i));
   s = s+nchoosek*termi;
end
pec(1,j) = s;							% coded word error probability
end

qq = [qc',qu',peu',pec'];
semilogy(zdB',qq)
xlabel('STw/No in dB')				% label x axis
ylabel('Probability')				% label y axis