interleaver.m

交织器的Matlab仿真

function pattern=interleaver_3GPP(x)
%****************************************************************
% 内容概述：3GPP标准交织器
% 参考文献：《3GPP TS 25.212 V6.5.0 (2005-06)》
%****************************************************************
%   K	Number of bits input to Turbo code internal interleaver
%   R	Number of rows of rectangular matrix
%   C	Number of columns of rectangular matrix
%   p	Prime number
%   v	Primitive root
%   T   Inter-row permutation patterns


K=length(x);

if K>=40 & K<=159
    R=5;
    T=[4, 3, 2, 1, 0]+1;
elseif (K>=160 & K<=200)|(K>=481 & K<=530)
    R=10;
    T=[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]+1;
elseif (K>=2281 & K<=2480)|(K>=3161 & K<=3210)
    R=20;
    T=[19, 9, 14, 4, 0, 2, 5, 7, 12, 18, 16, 13, 17, 15, 3, 1, 6, 11, 8, 10]+1;
else
    R=20;
    T=[19, 9, 14, 4, 0, 2, 5, 7, 12, 18, 10, 8, 13, 17, 3, 1, 16, 6, 15, 11]+1;
end
%(1)	确定交织器矩阵行数R

%(2)	Determine the prime number to be used in the intra-permutation, p,
%and the number of columns of rectangular matrix, C
p_table=[7	11	13	17	19	23	29	31	37	41	43 ...
    47	53	59	61	67	71	73	79	83	89	97 ...
    101	103	107	109	113	127	131	137	139	149	151 ...
    157	163	167	173	179	181	191	193	197	199	211 ...
    223	227	229	233	239	241	251	257];
if K>=481 & K<=530
    p=53;
    C=p;
else
    % 在p_table表中找到最小素数p的值
    ii=1;
    while (p_table(ii)+1)*R<K
        ii=ii+1;
    end
    p=p_table(ii);
    % 确定C  
    if K<=(p-1)*R
        C=p-1;
    elseif K>(p-1)*R & K<=R*p
        C=p;
    elseif K>R*p
        C=p+1;
    end
end
%(2)确定内部置换时的素数p	
%   根据p确定交织器矩阵的列数C

        
%(3)把输入比特序列写入R*C的交织矩阵中
if K~=R*C
    x(1,(K+1):(R*C))=0; 
end
%如果输入比特数不构R*C个，则其余补零
matrix_unpermutation=(reshape(x,C,R))';
%注意：这里的reshape是按照列排序的，还需要转置一下

% 行内交织
v_table=[
     3     2     2     3     2     5     2     3     2     6     3 ...
     5     2     2     2     2     7     5     3     2     3     5 ...
     2     5     2     6     3     3     2     3     2     2     6 ...
     5     2     5     2     2     2    19     5     2     3     2 ...
     3     2     6     3     7     7     6     3     ];
%(1)	从上表中选择本源根v
 if K>=481 & K<=530
     v=2;
 else
     v=v_table(ii);
 end
 
%(2)	构造行内交织的基本序列s(j) 
s(1)=1;
for j=2:p-1
    s(j)=mod(v*s(j-1),p);
end
%(3) 确定素数qi
q(1)=1;
q(1,2:R)=6;
for i=2:R
    while ((gcd(q(i),p-1)==1) & (q(i)>6) & (q(i)>q(i-1)))==0
        q(i)=q(i)+1;
    end
end
%(4)	把改变次序的 qi的值赋值给 ri
r(T)=q;

%(5)	进行行间交织
for i=1:R
    if C==p
        for j=1:p-1
            U(i,j)=s(mod(j*r(i),p-1)+1);
        end
        U(i,p)=0;
    elseif C==p+1
        for j=1:p-1
            U(i,j)=s(mod(j*r(i),p-1)+1);
        end
        U(i,p)=0;
        U(i,p+1)=p;
        if K==R*C & i==R
            temp=U(R,p+1);
            U(R,p+1)=U(R,1);
            U(R,1)=temp;
        end
    elseif C==p-1
        for j=1:p-1
            U(i,j)=s(mod(j*r(i),p-1)+1)-1;
        end
    end
end

for i=1:R
    matrix_intra_row_permutated(i,:)=matrix_unpermutation(i,U(i,:)+1);
end
    
for i=1:C
    matrix_interleaved(:,i)=matrix_intra_row_permutated(T,i);
end

k=1;
for i=1:C
    for j=1:R
         if matrix_interleaved(j,i)~=0
             pattern(k)=matrix_interleaved(j,i);
             k=k+1;
         end
    end
end