function pattern=interleaver_3GPP(x)
%****************************************************************
% 內容概述：3GPP標準交織器
% 創 建 人：朱殿榮/QQ:235347/MSN:njzdr@msn.com
% 單    位：南京郵電大學，通信工程系
% 創建時間：2005年9月11日
% 修改時間：
% 參考文獻：3GPP TS 25.212 V6.6.0 (2005-09)
%          3GPP TS 25.222 V6.2.0 (2004-12)
% 版權聲明：任何人均可復制、傳播、修改此文件，同時需保留原始版權信息。
%****************************************************************
%   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);
%(1)	Determine the number of rows of the rectangular matrix, R
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

%(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
    %Find minimum prime number p from p_table
    ii=1;
    while (p_table(ii)+1)*R<K
        ii=ii+1;
    end
    p=p_table(ii);
    %determine 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
        
%(3)Write the input bit sequence into the R*C rectangular matrix row by row
if K~=R*C
    x(1,(K+1):(R*C))=0; %dummy bits are padded 
end
matrix_unpermutation=(reshape(x,C,R))';
%注意：這里的reshape是按照列排序的，還需要轉置一下

%----------------------------Intra-row and inter-row permutations
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)	Select a primitive root v from the table
 if K>=481 & K<=530
     v=2;
 else
     v=v_table(ii);
 end
 
%(2)	Construct the base sequence s(j)   for intra-row permutation
s(1)=1;
for j=2:p-1
    s(j)=mod(v*s(j-1),p);
end
%(3)    determine the prime integer 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)	Permute the sequence  qi to make the sequence  ri
r(T)=q;

%(5)	Perform the i-th (i = 0, 1, …, R - 1) intra-row permutation
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