rayleighperformance.m

该MATLAB程序评估了viterbi算法在衰落信道下的卷积译码的性能

ad=[1,2,4,8];    
d =[6,8,10,12];  
Rc = 1/3;
SNRb=[10:0.5:20]; % 以 db 为单位,表示分集接收时的平均比特信噪比；

%soft decision
pe_soft = zeros(1,21);
Pe2=zeros(1,4);  % 成对差错概率
for j = 1:21
    p=1/(2+Rc*(10^(SNRb(j)/10)));   %求出比特差错率
    for i=1:4
        a=0;
        for k=0:(d(i)-1)
          a=a+combine(d(i)-1+k,k)*(1-p)^k;
        end
        Pe2(i)=(p^d(i))*a;
    end
    pe_soft(j) = ad*Pe2';
end
semilogy(SNRb,pe_soft,'r-*');
%grid on;
xlabel('分集接收时平均比特SNRb /db');
ylabel('比特差错率 Pe');
title('Rc=1/3 Soft Decision Vs. Hard Decision Performance');
hold on;

%hard decision(边界)
pe_hard = zeros(1,21);
for j = 1:21
    p=1/(2+Rc*(10^(SNRb(j)/10)));   %求出比特差错率
   for i = 1:4
    pe_single(i) = (4*p*(1-p))^(d(i)/2);
   end
pe_hard(j) = ad*pe_single';
end
%grid on;
semilogy(SNRb,pe_hard,'b-o');

% % %hard decision(精确)
% % p = [0:1:20];
%   for j = 1:21
%      p=1/(2+Rc*(10^(SNRb(j)/10)));   %求出比特差错率
%       for i = 1:4
%            pe_single_accuracy(i)=0.5*combine(d(i),d(i)/2)*(p^(d(i)/2))*((1-p)^(d(i)/2));
%       end
%      pe_hard_accuracy(j) = ad*pe_single_accuracy';
%   end
%  semilogy(SNRb,pe_hard_accuracy,'g--X');