smldpe54.m

二进制通信系统的进行蒙特卡罗仿真程序

function [p]=smldPe54(snr_in_dB)
% [p]=smldPe54(snr_in_dB)
%          SMLDPE54 finds the probability of error for the given
%          snr_in_dB,signal to noise ratio in dB.
E=1;
SNR=exp(snr_in_dB*log(10)/10);   % signal to noise ratio
sgma=E/sqrt(2*SNR);              % sigma,standard deviation of noise
N=10000;
% generation of the binary data source
for i=1:N,
    temp=rand;                   % a uniform random variable over (0,1)
    if(temp<0.5),
        dsource(i)=0;            % with probability 1/2,source output is 0
    else
        dsource(i)=1;            % with probability 1/2,source output is 1
    end
end;
% detection,and probability of error calculation
numoferr=0;
for i=1:N,
    % matched filter outputs
    if (dsource(i)==0),
        r0=E+gngauss(sgma);
        r1=gngauss(sgma);        % if the source outputs is "0"
    else
        r0=gngauss(sgma);
        r1=E+gngauss(sgma);      % if the source outputs is "1"
    end;
    % detector follows
    if (r0>r1),
        decis=0;                 % decision is "0"
    else
        decis=1;                 % decision is "!"
    end;
    if(decis~=dsource(i)),       % if it is an error,increase the error counter
        numoferr=numoferr+1;
    end;
end;
p=numoferr/N;