www.pudn.com > block_turbo_decode.rar > block_turbo_decode.m

function  ber = block_turbo_decode; 
clear all; 
% (64,57,4)*(64,57,4) BCH code   
n1 = 64; 
k1 = 57; 
delta1 = 4; 
 
n2 = 64; 
k2 = 57; 
delta2 = 4; 
 
x = round(rand(1, k1*k2));    % info. bits 
% place k1*k2 information bits in a matrix  
for i = 1:k1 
    for j = 1:k2 
        infor(i,j) = x(k2*(i-1)+j); 
    end 
end 
% coding the k1 row using code epslon2 
% g2(x)=x^6 + x + 1 
% define D2=[D0 D1 D2 D3 D4 D5] 
D2 = zeros(1,6); 
for i = 1:k1 
    for j = 1:k2 
        D2(1,1:6) = [infor(i,j) xor(infor(i,j),D2(1,1)) D2(1,2:5)]; 
    end 
    for k = 1:6 
        r2(i,k) = D2(1,7-k); 
    end 
     
    c_temp2(i,:) =[infor(i,:) r2(i,:)]; 
    temp2 = sum(c_temp2(i,:)); 
    temp2 = mod(temp2,2); 
    c2(i,:) = [c_temp2(i,:) temp2]; 
end 
% coding the n2 columns using code epslon1 
% g1(x)=x^6 + x + 1 
D1 = zeros(1,6); 
for j = 1:n2 
    for i = 1:k1 
        D1(1,1:6) = [c2(i,j) xor(c2(i,j),D1(1,1)) D1(1,2:5)]; 
    end 
     
    for k = 1:6 
        r1(k,j) = D1(1,7-k); 
    end 
    c_temp1(:,j) =[c2(:,j); r1(:,j)]; 
    temp1 = sum(c_temp1(:,j)); 
    temp1 = mod(temp1,2); 
    c(:,j) = [c_temp1(:,j); temp1]; 
end 
% bpsk  
x = 2*c - ones(n1,n2); 
% awgn channel 
EbN0db = 0.5; 
rate = 0.793; 
en = 10^(EbN0db/10); 
sigma = 1/sqrt(2*rate*en); 
r = x + sigma*randn(n1,n2); 
 
%for k =1:8 
    w(:,:) = zeros(n1,n2); 
    wrot(:,:) = zeros(n2,n1); 
%end 
     
for i=1:n1 
    R(i,:) = r(i,:); 
    if i > k1 
        R(i,:) = zeros(1,n2); 
    end 
end 
 
belta = [0 0.5 0.7 0.9 1 1 1 1]; 
sclar = [0.2 0.3 0.5 0.7 0.9 1 1 1]; 
for m =1:8 
    % ÐÐÒëÂë 
    w(1:k1,:) = decode(k1,n2,belta(m),R(1:k1,:),m); 
    R(:,:) = r(:,:) + w(:,:)*sclar(m); 
     
    % ÁÐÒëÂë 
    wrot(:,:) = decode(n2,n1,belta(m),R(:,:)',m); 
    w(:,:) = wrot(:,:)'; 
    R(:,:) = r(:,:) + w(:,:)*sclar(m); 
end 
 
for i = 1:k1 
    for j = 1:k2 
        if R(i,j) > 0 
            xhat(i,j) = 1; 
        else 
            xhat(i,j) = 0; 
        end 
    end 
end 
 
error = 0; 
for i = 1:k1 
    for j = 1:k2 
        if xhat(i,j) ~= infor(i,j) 
            error = error + 1; 
        end 
    end 
end 
ber = error/(k1*k2);