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 b_i are given by:

where i = 0,…,31. N_{TFCI 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 (N_{TFCI code word} =4) for a single TFCI bit and 8-bit transmission (N_{TFCI 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 N_{TFCI code word}=4, the TFCI codeword {b₀, b₁, b₂, b₃} is equal to the sequence {a₀, a₀, a₀, a₀}.

In the case of N_{TFCI 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 b_j are given by:

where i = 0,…,15. N_{TFCI 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 N_{TFCI code word}, denote the TFCI code word bits by b_k where k=0… N_{TFCI 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 P_q, q = 0, …, N_PI-1, P_q  {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 P_q. The length L_PI of the paging indicator is L_PI=2, L_PI=4 or L_PI=8 symbols. N_PIB = 2*N_PI*L_PI bits are used for the paging indicator transmission in one radio frame. The mapping of the paging indicators to the bits e_i, i = 1, …, N_PIB 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 N_PIB of bits used for the transmission of paging indicators, the sequence e = {e₁, e₂, …, e_NPIB} is extended by S–N_PIB bits that are set to zero, resulting in a sequence h = {h₁, h₂, …, h_S}:

The bits h_k , k = 1, …, S on the PICH then undergo bit scrambling as defined in section 4.2.9.

The bits s_k, 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 N_q, q = 0, …, N_n-1, N_q  {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 N_q. The length L_NI of the MBMS notification indicator is L_NI=2, L_NI=4 or L_NI=8 symbols. N_NIB = 2*N_n*L_NI bits are used for the MBMS notification indicator transmission in one MICH. The mapping of the MBMS notification indicators to the bits e_i, i = 1, …, N_NIB 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 N_NIB of bits used for the transmission of MBMS notification indicators, the sequence e = {e₁, e₂, …, e_NNIB} is extended by S–N_NIB bits that are set to zero, resulting in a sequence h = {h₁, h₂, …, h_S}:

The bits h_k , k = 1, …, S on the MICH then undergo bit scrambling as defined in section 4.2.9.

The bits s_k, k = 1, …, S output from the bit scrambler are then transmitted over the air as shown in [7].