4.2.5 1^st interleaving

25.2123GPPMultiplexing and channel coding (FDD)Release 17TS

4.2.5.1 Void

4.2.5.2 1^st interleaver operation

The 1^st 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 X_i the number of bits. Here X_i is guaranteed to be an integer multiple of F_i. The output bit sequence from the block interleaver is derived as follows:

(1) Select the number of columns C1 from Table 4 or 4A depending on the TTI. The columns are numbered 0, 1, …, C1 – 1 from left to right. Table 4A is used in uplink when UL_DPCH_10ms_Mode is configured by higher layers, and Table 4 is used in all other cases.

(2) Determine the number of rows of the matrix, R1 defined as

R1 = X_i / 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 P1_C1 (j) is the original column position of the j-th permuted column. After permutation of the columns, the bits are denoted by y_ik:

(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 for downlink, and for uplink when UL_DPCH_10ms_Mode is not configured by higher layers

TTI	Number of columns C1	Inter-column permutation patterns <P1C1(0), P1C1(1), …, P1C1(C1-1)>
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>

Table 4A: Inter-column permutation patterns for 1st interleaving for uplink when UL_DPCH_10ms_Mode is configured by higher layers

TTI	Number of columns C1	Inter-column permutation patterns <P1C1(0), P1C1(1), …, P1C1(C1-1)>
20 ms	1	<0>
40 ms	2	<0,1>
80 ms	4	<0,2,1,3>

4.2.5.3 Relation between input and output of 1^st interleaving in uplink

The bits input to the 1^st interleaving are denoted by , where i is the TrCH number and T_i the number of bits. Hence, x_i,k = t_i,k and X_i = T_i.

The bits output from the 1^st interleaving are denoted by , and d_i,k = y_i,k.

4.2.5.4 Relation between input and output of 1^st interleaving in downlink

If fixed positions of the TrCHs in a radio frame is used then the bits input to the 1^st interleaving are denoted by , where i is the TrCH number. Hence, x_ik = h_ik and X_i = D_i.

If flexible positions of the TrCHs in a radio frame is used then the bits input to the 1^st interleaving are denoted by , where i is the TrCH number. Hence, x_ik = g_ik and X_i = G_i.

The bits output from the 1^st interleaving are denoted by , where i is the TrCH number and Q_i is the number of bits. Hence, q_ik = y_ik, Q_i = F_iH_i if fixed positions are used, and Q_i = G_i if flexible positions are used. H_i is defined in subclause 4.2.9.1.