WCDMA3G CodeBlkSeg

WCDMA3G_CodeBlkSeg

Description: Transport block concatenation and code block segmentation
Library: 3GPPFDD 10-99, Channel Coding
Class: SDFWCDMA3G_CodeBlkSeg

Parameters

Pin Inputs

Pin Outputs

Notes/Equations

1. This model is used to implement transport block concatenation and code block segmentation. All transport blocks in one transmission time interval are serially concatenated. If the number of bits in one TTI is larger than the maximum size of code block, the code block segmentation is performed after the concatenation of all transport blocks. The maximum size of the code blocks depend on the channel coding scheme (convolutional coding, turbo coding, no coding) used for transport channel in downlink and uplink. The number of input and output tokens are listed in the following table.
   

   Input and Output Tokens

   DCHType	TTI	Input Tokens		Output Tokens
   		in	TF	out Downlink	out Uplink	CurSize Tokens
   DCH_8_kbps	10 ms	96	1	96	104	1
   	20 ms	176	2	176	184	1
   	40 ms	336	4	336	344	1
   	80 ms	656	8	656	672	1
   DCH_16_kbps	10 ms	176	1	184	184	1
   	20 ms	336	2	344	344	1
   	40 ms	656	4	672	672	2
   	80 ms	1296	8	1320	1320	3
   DCH_32_kbps	10 ms	336	1	344	344	1
   	20 ms	656	2	672	672	2
   	40 ms	1296	4	1320	1320	3
   	80 ms	2576	8	2628	2628	6
   DCH_64_kbps	10 ms	656	1	656	656	1
   	20 ms	1296	2	1296	1296	1
   	40 ms	2576	4	2576	2576	1
   	80 ms	5136	8	5136	5136	2
   DCH_128_kbps	10 ms	1296	1	1296	1296	1
   	20 ms	2576	2	2576	2576	1
   	40 ms	5136	4	5136	5136	2
   	80 ms	10256	8	10257	10257	3
   DCH_256_kbps	10 ms	2576	1	2576	2576	1
   	20 ms	5136	2	5136	5136	2
   	40 ms	10256	4	10257	10257	3
   	80 ms	20496	8	20500	20500	5
   DCH_512_kbps	10 ms	5136	1	5136	5136	2
   	20 ms	10256	2	10257	10257	3
   	40 ms	20496	4	20500	20500	5
   	80 ms	40976	8	40977	40977	9
   DMCH_2_4_kbps	40 ms	112	4	120	120	1
   DMCH_12_2_kbps	20 ms	260	2	268	268	1
   DMCH_64_kbps	20 ms	1296	2	1296	1296	1
   DMCH_144_kbps	20 ms	2896	2	2896	2896	1
   DMCH_384_kbps	20 ms	7696	2	7696	7696	2
   DMCH_2048_kbps	20 ms	40976	2		40977	9
   BCH_11_1_kbps	10 ms	127	1	135		1
   BCH_12_3_kbps	20 ms	262	2	270		1

2. Model functions
   Input bits are read from the input buffer. The input transport format is read to determine which coding scheme to use.
   Concatenation of transport blocks is performed.
   Bits input to the transport block concatenation are denoted by b_im1,b_im2,...b_imBi, where i is the TrCH number, m is the transport block number, B_i is the number of bits in each block (including CRC). The number of transport block on TrCH i is denoted by M_i. Bits after concatenation are denoted by x_i1, x_i2, ..., x_iXi, where i is the TrCH number and X_i = M_i Bi. These are defined by the following relations:

   x_ik = b_i1k, k = 1,2,...,B_i
   x_ik = b_i,2,(k-Bi), k = B_i+1,B_i+2,...,2B_i.
   .
   .
   x_ik = b_{i,Mi,(k-(Mi-1)Bi)}, k = (Mi-1)B_i+1,(Mi-1)B_i+2, ..., MiB_i

   In a W-CDMA system, only one transport block is produced within one TTI, so concatenation is only performed while Mi = 1.
   If data size X_i after concatenation is larger than the maximum code block size Z, the segmentation of bit sequence is performed. The code blocks after segmentation are of the same size. The number of code blocks on TrCH i is denoted by C_i. If the number of bits input to the segmentation X_i is not a multiple of C_i, filler bits are added to the last block. The filler bits are transmitted and these are always set to 0. The maximum code block size are:

   convolutional coding: Z = 504
   turbo coding: Z = 5114
   no coding: Z = unlimited

   Bits output from code block segmentation are denoted by O_ir1,O_ir2,...,O_irKi, where i is TrCH number, r is code block number, K_i is number of bits.

   Number of code blocks: C_i = [ X_i / Z ]
   Number of bits in each code block: K_i = [ X_i / C_i ]
   Number of filler bits: Y_i = C_i K_i - X_i

   If X_i <= Z, then O_i1k =X_ik, and K_i =X_i
   If X_i > Z, then

   O_i1k = x_ik, k = 1,2,...,K_i
   O_i2k = x_i,(k+Ki), k = 1,2,...,K_i.
   .
   .
   O_iCik = x_{i,(k+(Ci-1)Ki)}, k = 1,2,...,K_i - Y_i
   O_iCik = 0, k = K_i - Y_i+ 1, ..., K_i

   In W-CDMA systems, while convolutional coding scheme is used, (K-1) tails bits are added to the end of every code block for convenience, K is the constraint length of convolutional code.
   The following figure illustrates the position of the code block for the coding schemes.
   All data and current valid data size are output into the output buffer.
   
   

   Position of Code Blocks for Different Channel Coding Schemes

References

1. 3GPP Technical Specification TS25.212 V3.0.0,"Multiplexing and Channel Coding (FDD)," October 1999.
2. 3GPP Technical Specification TS25.101 V3.0.0,"UE Radio transmission and Reception (FDD)," October 1999.
3. 3GPP Technical Specification TS25.104 V3.0.0,"UTRA(BS) FDD: transmission and Reception," October 1999.