4.3 Coding for layer 1 control for the 3.84 Mcps and 7.68Mcps TDD options
25.2223GPPMultiplexing and channel coding (TDD)Release 17TS
4.3.1 Coding of transport format combination indicator (TFCI)
Encoding of the TFCI depends on its length. If there are 6-10 bits of TFCI the channel encoding is done as described in subclause 4.3.1.1. Also specific coding of less than 6 bits is possible as explained in subclause 4.3.1.2.
4.3.1.1 Coding of long TFCI lengths
The TFCI is encoded using a (32, 10) sub-code of the second order Reed-Muller code. The coding procedure is as shown in figure 6.
Figure 6: Channel coding of the TFCI bits
If the TFCI consists of less than 10 bits, it is padded with zeros to 10 bits, by setting the most significant bits to zero. TFCI is encoded by the (32,10) sub-code of second order Reed-Muller code. The code words of the (32,10) sub-code of second order Reed-Muller code are linear combination of some among 10 basis sequences. The basis sequences are as follows in table 8.
Table 8: Basis sequences for (32,10) TFCI code
I |
Mi,0 |
Mi,1 |
Mi,2 |
Mi,3 |
MI,4 |
Mi,5 |
Mi,6 |
Mi,7 |
Mi,8 |
Mi,9 |
---|---|---|---|---|---|---|---|---|---|---|
0 |
1 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
0 |
0 |
2 |
1 |
1 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
3 |
0 |
0 |
1 |
0 |
0 |
1 |
1 |
0 |
1 |
1 |
4 |
1 |
0 |
1 |
0 |
0 |
1 |
0 |
0 |
0 |
1 |
5 |
0 |
1 |
1 |
0 |
0 |
1 |
0 |
0 |
1 |
0 |
6 |
1 |
1 |
1 |
0 |
0 |
1 |
0 |
1 |
0 |
0 |
7 |
0 |
0 |
0 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
8 |
1 |
0 |
0 |
1 |
0 |
1 |
1 |
1 |
1 |
0 |
9 |
0 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
1 |
1 |
10 |
1 |
1 |
0 |
1 |
0 |
1 |
0 |
0 |
1 |
1 |
11 |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
12 |
1 |
0 |
1 |
1 |
0 |
1 |
0 |
1 |
0 |
1 |
13 |
0 |
1 |
1 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
14 |
1 |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
1 |
1 |
15 |
1 |
0 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
0 |
16 |
0 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
1 |
17 |
1 |
1 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
0 |
18 |
0 |
0 |
1 |
0 |
1 |
1 |
0 |
1 |
1 |
1 |
19 |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
1 |
0 |
1 |
20 |
0 |
1 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
21 |
1 |
1 |
1 |
0 |
1 |
1 |
0 |
1 |
1 |
1 |
22 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
1 |
0 |
0 |
23 |
1 |
0 |
0 |
1 |
1 |
1 |
1 |
1 |
0 |
1 |
24 |
0 |
1 |
0 |
1 |
1 |
1 |
1 |
0 |
1 |
0 |
25 |
1 |
1 |
0 |
1 |
1 |
1 |
1 |
0 |
0 |
1 |
26 |
0 |
0 |
1 |
1 |
1 |
1 |
0 |
0 |
1 |
0 |
27 |
1 |
0 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
0 |
28 |
0 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
0 |
29 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
30 |
0 |
0 |
0 |
0 |
0 |
1 |
0 |
0 |
0 |
0 |
31 |
0 |
0 |
0 |
0 |
1 |
1 |
1 |
0 |
0 |
0 |
The TFCI bits a0 , a1 , a2 , a3 , a4 , a5 , a6 , a7 , a8 , a9 (where a0 is LSB and a9 is MSB) shall correspond to the TFC index (expressed in unsigned binary form) defined by the RRC layer to reference the TFC of the CCTrCH in the associated radio frame.
The output TFCI code word bits bi are given by:
where i = 0,…,31. NTFCI code word = 32.
4.3.1.2 Coding of short TFCI lengths
4.3.1.2.1 Coding very short TFCIs by repetition
If the number of TFCI bits is 1 or 2, then repetition will be used for coding. In this case each bit is repeated to a total of 4 times giving 4-bit transmission (NTFCI code word =4) for a single TFCI bit and 8-bit transmission (NTFCI code word =8) for 2 TFCI bits. The TFCI bit(s) a0 (or a0 and a1 where a0 is the LSB) shall correspond to the TFC index (expressed in unsigned binary form) defined by the RRC layer to reference the TFC of the CCTrCH in the associated radio frame.
In the case of NTFCI code word=4, the TFCI codeword {b0, b1, b2, b3} is equal to the sequence {a0, a0, a0, a0}.
In the case of NTFCI code word=8, the TFCI codeword {b0, b1, … , b7} is equal to the sequence {a0, a1, a0, a1, a0, a1, a0, a1}.
4.3.1.2.2 Coding short TFCIs using bi-orthogonal codes
If the number of TFCI bits is in the range 3 to 5 the TFCI is encoded using a (16, 5) bi-orthogonal (or first order Reed-Muller) code. The coding procedure is as shown in figure 7.
Figure 7: Channel coding of short length TFCI bits
If the TFCI consists of less than 5 bits, it is padded with zeros to 5 bits, by setting the most significant bits to zero. The code words of the (16,5) bi-orthogonal code are linear combinations of 5 basis sequences as defined in table 9.
Table 9: Basis sequences for (16,5) TFCI code
i |
Mi,0 |
Mi,1 |
Mi,2 |
Mi,3 |
Mi,4 |
---|---|---|---|---|---|
0 |
1 |
0 |
0 |
0 |
1 |
1 |
0 |
1 |
0 |
0 |
1 |
2 |
1 |
1 |
0 |
0 |
1 |
3 |
0 |
0 |
1 |
0 |
1 |
4 |
1 |
0 |
1 |
0 |
1 |
5 |
0 |
1 |
1 |
0 |
1 |
6 |
1 |
1 |
1 |
0 |
1 |
7 |
0 |
0 |
0 |
1 |
1 |
8 |
1 |
0 |
0 |
1 |
1 |
9 |
0 |
1 |
0 |
1 |
1 |
10 |
1 |
1 |
0 |
1 |
1 |
11 |
0 |
0 |
1 |
1 |
1 |
12 |
1 |
0 |
1 |
1 |
1 |
13 |
0 |
1 |
1 |
1 |
1 |
14 |
1 |
1 |
1 |
1 |
1 |
15 |
0 |
0 |
0 |
0 |
1 |
The TFCI bits a0 , a1 , a2 , a3 , a4 (where a0 is LSB and a4 is MSB) shall correspond to the TFC index (expressed in unsigned binary form) defined by the RRC layer to reference the TFC of the CCTrCH in the associated radio frame.
The output code word bits bj are given by:
where i = 0,…,15. NTFCI code word = 16.
4.3.1.3 Mapping of TFCI code word
The mapping of the TFCI code word to the TFCI bit positions in a timeslot shall be as follows.
Denote the number of bits in the TFCI code word by NTFCI code word, denote the TFCI code word bits by bk where k=0… NTFCI code word -1.
Figure 8: Mapping of TFCI code word bits to timeslot
The locations of the first and second parts of the TFCI code word in the timeslot is defined in [7].
If the shortest transmission time interval of any constituent TrCH is at least 20 ms the successive TFCI code words in the frames in the TTI shall be identical. If TFCI is transmitted on multiple timeslots in a frame each timeslot shall have the same TFCI code word.
4.3.2 Coding and Bit Scrambling of the Paging Indicator
The paging indicator Pq, q = 0, …, NPI-1, Pq {0, 1} is an identifier to instruct the UE whether there is a paging message for the groups of mobiles that are associated to the PI, calculated by higher layers, and the associated paging indicator Pq. The length LPI of the paging indicator is LPI=2, LPI=4 or LPI=8 symbols. NPIB = 2*NPI*LPI bits are used for the paging indicator transmission in one radio frame. The mapping of the paging indicators to the bits ei, i = 1, …, NPIB is shown in table 10.
Table 10: Mapping of the paging indicator
Pq |
Bits {e2Lpi*q+1, e2Lpi*q+2, … ,e2Lpi*(q+1) } |
Meaning |
0 |
{0, 0, …, 0} |
There is no necessity to receive the PCH |
1 |
{1, 1, …, 1} |
There is the necessity to receive the PCH |
If the number S of bits in one radio frame available for the PICH is bigger than the number NPIB of bits used for the transmission of paging indicators, the sequence e = {e1, e2, …, eNPIB} is extended by S–NPIB bits that are set to zero, resulting in a sequence h = {h1, h2, …, hS}:
The bits hk , k = 1, …, S on the PICH then undergo bit scrambling as defined in section 4.2.9.
The bits sk, k = 1, …, S output from the bit scrambler are then transmitted over the air as shown in [7].
4.3.3 Coding and Bit Scrambling of the MBMS Notification Indicator
The MBMS notification indicator Nq, q = 0, …, Nn-1, Nq {0, 1}, is an identifier to instruct UEs whether there is an MBMS notification indication for the groups of MBMS services that are associated to the NI, calculated by higher layers, and the associated MBMS notification indicator Nq. The length LNI of the MBMS notification indicator is LNI=2, LNI=4 or LNI=8 symbols. NNIB = 2*Nn*LNI bits are used for the MBMS notification indicator transmission in one MICH. The mapping of the MBMS notification indicators to the bits ei, i = 1, …, NNIB is shown in table 10A.
Table 10A: Mapping of the MBMS notification indicator
Nq |
Bits {e2Lni*q+1, e2Lni*q+2, … ,e2Lni*(q+1) } |
0 |
{0, 0, …, 0} |
1 |
{1, 1, …, 1} |
If the number S of bits available for the MICH is bigger than the number NNIB of bits used for the transmission of MBMS notification indicators, the sequence e = {e1, e2, …, eNNIB} is extended by S–NNIB bits that are set to zero, resulting in a sequence h = {h1, h2, …, hS}:
The bits hk , k = 1, …, S on the MICH then undergo bit scrambling as defined in section 4.2.9.
The bits sk, k = 1, …, S output from the bit scrambler are then transmitted over the air as shown in [7].