4.2.5 1st interleaving
25.2223GPPMultiplexing and channel coding (TDD)Release 17TS
The 1st interleaving is a block interleaver with inter-column permutations. The input bit sequence to the block interleaver is denoted by , where i is TrCH number and Xi the number of bits. Here Xi is guaranteed to be an integer multiple of the number of radio frames in the TTI. The output bit sequence from the block interleaver is derived as follows:
1) select the number of columns C1 from table 4 depending on the TTI. The columns are numbered 0, 1, …, C1 – 1 from left to right.
2) determine the number of rows of the matrix, R1 defined as
R1 = Xi / C1.
The rows of the matrix are numbered 0, 1, …, R1 – 1 from top to bottom.
3) write the input bit sequence into the R1 C1 matrix row by row starting with bit
in column 0 of row 0 and ending with bit
in column C1 – 1 of row R1 – 1:
4) Perform the inter-column permutation for the matrix based on the pattern shown in table 4, where P1C1(j) is the original column position of the j-th permuted column. After permutation of the columns, the bits are denoted by yi,k:
5) Read the output bit sequence of the block interleaver column by column from the inter-column permuted R1
C1 matrix. Bit
corresponds to row 0 of column 0 and bit
corresponds to row R1 – 1 of column C1 – 1.
Table 4 Inter-column permutation patterns for 1st interleaving
TTI |
Number of columns C1 |
Inter-column permutation patterns <P1C1(0), P1C1(1), …, P1C1(C1-1)> |
5ms(*1), 10 ms |
1 |
<0> |
20 ms |
2 |
<0,1> |
40 ms |
4 |
<0,2,1,3> |
80 ms |
8 |
<0,4,2,6,1,5,3,7> |
(*1) can be used for PRACH for 1.28 Mcps TDD
4.2.5.1 Relation between input and output of 1st interleaving
The bits input to the 1st interleaving are denoted by , where i is the TrCH number and Ti the number of bits. Hence, xi,k = ti,k and Xi = Ti.
The bits output from the 1st interleaving are denoted by , and di,k = yi,k.