4.6 Coding for HS-SCCH type 1

25.2123GPPMultiplexing and channel coding (FDD)Release 17TS

4.6.1 Overview

HS-SCCH shall be of type 1 when the following two conditions are both true:

– the UE is not configured in MIMO mode and not in MIMO mode with four transmit antennas, and

– the conditions for usage of HS-SCCH type 2 are not met.

In this section, the terms “HS-SCCH” and “HS-SCCH type 1” are used interchangeably.

The following information is transmitted by means of the HS-SCCH type 1 physical channel.

– Channelization-code-set information (7 bits): xccs,1, xccs,2, …, xccs,7

– Modulation scheme information (1 bit): xms,1

– Transport-block size information (6 bits): xtbs,1, xtbs,2, …, xtbs,6

– Hybrid-ARQ process information (3 bits): xhap,1, xhap,2, xhap,3

– Redundancy and constellation version (3 bits): xrv,1, xrv,2, xrv,3

– New data indicator (1 bit): xnd,1

– UE identity (16 bits): xue,1, xue,2, …, xue,16

For an HS-SCCH order,

– xccs,1, xccs,2, …, xccs,7, xms,1 shall be set to ”11100000’

– xtbs,1, xtbs,2, …, xtbs,4 shall be set to ”1111’

– xtbs,5, tbs,6 shall be set to xeodt,1, xeodt,2

– xhap,1, xhap,2, xhap,3, xrv,1, xrv,2, xrv,3 shall be set to xodt,1, xodt,2, xodt,3, xord,1, xord,2, xord,3

– xnd,1 is reserved

where xeodt,1, xeodt,2, xodt,1, xodt,2, xodt,3, xord,1, xord,2, xord,3 are defined in subclause 4.6C.

Figure 19 below illustrates the overall coding chain for HS-SCCH type 1.

Figure 19: Coding chain for HS-SCCH type 1

4.6.2 HS-SCCH information field mapping

4.6.2.1 Redundancy and constellation version coding

The redundancy version (RV) parameters r, s and constellation version parameter b are coded jointly to produce the value Xrv. Xrv is alternatively represented as the sequence xrv,1, xrv,2, xrv,3 where xrv,1 is the MSB. This is done according to tables 12 and 13 according to the modulation mode used:

Table 12: RV coding for 16QAM and 64QAM

Xrv (value)

s

R

b

0

1

0

0

1

0

0

0

2

1

1

1

3

0

1

1

4

1

0

1

5

1

0

2

6

1

0

3

7

1

1

0

Table 13: RV coding for QPSK

Xrv (value)

s

r

0

1

0

1

0

0

2

1

1

3

0

1

4

1

2

5

0

2

6

1

3

7

0

3

4.6.2.2 Modulation scheme mapping

The value of xms,1 is derived from the modulation and given by the following:

4.6.2.3 Channelization code-set mapping

The channelization code-set bits xccs,1, xccs,2, …, xccs,7 are coded according to the following:

Given P (multi-)codes starting at code O, and given the HS-SCCH number if 64QAM is configured for the UE and xms,1=1, calculate the information-field using the unsigned binary representation of integers calculated by the expressions,

for the first three bits (code group indicator) of which xccs,1 is the MSB:

xccs,1, xccs,2, xccs,3 = min(P-1,15-P)

If 64QAM is not configured for the UE, or if 64QAM is configured and xms,1=0, then

for the last four bits (code offset indicator) of which xccs,4 is the MSB:

xccs,4, xccs,5, xccs,6, xccs,7 = |O-1-P/8 *15|

Otherwise (i.e. if 64QAM is configured for the UE and xms,1=1),

P and O shall fulfil |O-1-P/8 *15| mod 2 = (HS‑SCCH number) mod 2, and then

xccs,4, xccs,5, xccs,6, xccs,dummy = |O-1-P/8 *15|, where xccs,dummy is a dummy bit that is not transmitted on HS-SCCH.

Furthermore,

.

The definitions of P and O are given in [3]. The HS-SCCH number is given by the position in the list of HS-SCCH Channelisation Code Informations signalled by higher layers. The HS-SCCH number is associated with the code offset indicator and code group indicator as described above if 64QAM is configured for the UE and xms,1=1.

4.6.2.4 UE identity mapping

The UE identity is the HS-DSCH Radio Network Identifier (H-RNTI) defined in [13]. This is mapped such that xue,1 corresponds to the MSB and xue,16 to the LSB, cf. [14].

4.6.2.5 HARQ process identifier mapping

Hybrid-ARQ process information (3 bits) xhap,1, xhap,2, xhap,3 is the unsigned binary representation of the HARQ process identifier where xhap,1 is MSB.

4.6.2.6 Transport block size index mapping

Transport-block size information (6 bits) xtbs,1, xtbs,2, …, xtbs,6 is unsigned binary representation of the transport block size index where xtbs,1 is MSB.

4.6.3 Multiplexing of HS-SCCH information

The channelization-code-set information xccs,1, xccs,2, …, xccs,7 and modulation-scheme information xms,1 are multiplexed together. This gives a sequence of bits x1,1, x1,2, …, x1,8 where

x1,i = xccs,i i=1,2,…,7

x1,i = xms,i-7 i=8

The transport-block-size information xtbs,1, xtbs,2, …, xtbs,6, Hybrid-ARQ-process information xhap,1,xhap,2, xhap,3, redundancy-version information xrv,1, xrv,2, xrv,3 and new-data indicator xnd,1 are multiplexed together. This gives a sequence of bits x2,1, x2,2, …, x2,13 where

x2,i = xtbs,i i=1,2,…,6

x2,i = xhap,i-6 i=7,8,9

x2,i = xrv,i-9 i=10,11,12

x2,i = xnd,i-12 i=13

4.6.4 CRC attachment for HS-SCCH

From the sequence of bits x1,1, x1,2, …, x1,8, x2,1, x2,2, …, x2,13 a 16 bits CRC is calculated according to Clause 4.2.1.1. This gives a sequence of bits c1, c2, …, c16 where

k=1,2,…,16

This sequence of bits is then masked with the UE Identity xue,1, xue,2, …, xue,16 and then appended to the sequence of bits x2,1, x2,2, …, x2,13 to form the sequence of bits y1, y2, …, y29, where

yi = x2,i i=1,2,…,13

yi = (ci-13 + xue,i-13 ) mod 2 i=14,15,…,29

4.6.5 Channel coding for HS-SCCH

Rate 1/3 convolutional coding, as described in Clause 4.2.3.1, is applied to the sequence of bits x1,1,x1,2, …,x1,8. This gives a sequence of bits z1,1, z1,2, …, z1,48.

Rate 1/3 convolutional coding, as described in Clause 4.2.3.1, is applied to the sequence of bits y1, y2, …, y29. This gives a sequence of bits z2,1, z2,2, …, z2,111.

Note that the coded sequence lengths result from the termination of K=9 convolutional coding being fully applied.

4.6.6 Rate matching for HS-SCCH

From the input sequence z1,1, z1,2, …, z1,48 the bits z1,1, z1,2, z1,4, z1,8, z1,42, z1,45, z1,47, z1,48 are punctured to obtain the output sequence r1,1,r1,2…r1,40.

From the input sequence z2,1, z2,2, …, z2,111 the bits z2,1, z2,2, z2,3, z2,4, z2,5, z2,6, z2,7, z2,8, z2,12, z2,14, z2,15, z2,24, z2,42, z2,48, z2,54, z2,57, z2,60, z2,66, z2,69, z2,96, z2,99, z2,101, z2,102, z2,104, z2,105, z2,106, z2,107, z2,108, z2,109, z2,110, z2,111 are punctured to obtain the output sequence r2,1,r2,2…r2,80.

4.6.7 UE specific masking for HS-SCCH

The rate matched bits r1,1,r1,2…r1,40 shall be masked in an UE specific way using the UE identity xue,1, xue,2, …, xue,16, to produce the bits s1,1,s1,2…s1,40.

Intermediate code word bits bi, i=1,2…,48, are defined by encoding the UE identity bits using the rate ½ convolutional coding described in Clause 4.2.3.1. Eight bits out of the resulting 48 convolutionally encoded bits are punctured using the rate matching rule of Clause 4.6.6 for the HS-SCCH part 1 sequence, that is, the intermediate code word bits b1, b2, b4, b8, b42, b45, b47, b48, are punctured to obtain the 40 bit UE specific scrambling sequence c1, c2, ….c40. .

The mask output bits s1,1,s1,2…s1,40 are calculated as follows:

s1,k =(r1,k + ck) mod 2 for k = 1,2…40

4.6.8 Physical channel mapping for HS-SCCH

The HS-SCCH sub-frame is described in[2].

The sequence of bits s1,1, s1,2,, …, s1,40 is mapped to the first slot of the HS-SCCH sub frame. The bits s1,k are mapped to the PhCHs so that the bits for each PhCH are transmitted over the air in ascending order with respect to k.

The sequence of bits r2,1, r2,2,, …,,r2,80 is mapped to the second and third slot of the HS-SCCH sub frame. The bits r2,k are mapped to the PhCHs so that the bits for each PhCH are transmitted over the air in ascending order with respect to k.