cer2ber.m

经典书籍《通信系统仿真原理与无线应用》chap8部分课后题仿真源代码

function [ber] = cer2ber(q,n,d,t,ps)
% Converts channel symbol error rate to decoded BER.
lnps = length(ps);       % length of error vector
ber = zeros(1,lnps);     % initialize output vector
for k=1:lnps            % iterate error vector
cer = ps(k);            % channel symbol error rate
sum1 = 0; sum2 = 0;    % initialize sums
%
% first loop eveluates first sum
%
for i=(t+1):d
term = nkchoose(n,i)*(cer^i)*((1-cer))^(n-i);
sum1 = sum1+term;
end
%
% second loop evaluates second sum
%
for i=(d+1):n
term = i*nkchoose(n,i)*(cer^i)*((1-cer)^(n-i));
sum2 = sum2+term;
end
%
% compute BER (output)
%
ber(k) = (q/(2*(q-1)))*((d/n)*sum1+(1/n)*sum2);
end
% End of function file.