7A Synchronisation codes for the 7.68 Mcps option
25.2233GPPRelease 17Spreading and modulation (TDD)TS
7A.1 Code Generation
The primary synchronisation code (PSC), Cp , is constructed as a so-called generalised hierarchical Golay sequence. The PSC is furthermore chosen to have good aperiodic auto correlation properties.
Define a = < x1, x2, x3, …, x16 > = < 1, 1, 1, 1, 1, 1, -1, -1, 1, -1, 1, -1, 1, -1, -1, 1 >
The PSC of length 512 chips is generated by repetition coding and repeating the sequence ‘a’ modulated by a Golay complementary sequence and creating a complex-valued sequence with identical real and imaginary components.
The PSC, Cp , is defined as Cp = < y(0),y(0),y(1),y(1),y(2),y(2)…,y(255),y(255) >
where
and the left most index corresponds to the chip transmitted first in time.
The 12 secondary synchronization codes, {C0, C1, C3, C4, C5, C6, C8, C10, C12, C13, C14,C15 } are complex valued with identical real and imaginary components, and are constructed from repetition coding of the position wise multiplication of a Hadamard sequence and a sequence z, defined as
z = 
, where
b = 
and x1, x2, x3, …, x16 are the same as in the definition of the sequence ‘a’ above.
The Hadamard sequences are obtained as the rows in a matrix H8 constructed recursively by:
The rows are numbered from the top starting with row 0 (the all ones sequence).
Denote the n:th Hadamard sequence hn as a row of H8 numbered from the top, n = 0, 1, 2, …, 255, in the sequel.
Furthermore, let hm(l) and z(l) denote the lth symbol of the sequence hm and z, respectively where l = 0, 1, 2, …, 255 and l = 0 corresponds to the leftmost symbol.
The i:th secondary SCH code word, Ci, i = 0, 1, 3, 4, 5, 6, 8, 10, 12, 13, 14, 15 is of length 512 chips and is then defined as
Ci = (1 + j) <hm(0) z(0), hm(0) z(0), hm(1) z(1), hm(1) z(1), …, hm(255) z(255) , hm(255) z(255)>,
where m = (16i) and the leftmost chip in the sequence corresponds to the chip transmitted first in time.
7A.2 Code Allocation
Three secondary SCH codes are QPSK modulated and transmitted in parallel with the primary synchronization code. The QPSK modulation carries the following information:
– the code group that the base station belongs to (32 code groups:5 bits; Cases 1, 2);
– the position of the frame within an interleaving period of 20 msec (2 frames:1 bit, Cases 1, 2);
– the position of the SCH slot(s) within the frame (2 SCH slots:1 bit, Case 2).
The QPSK modulation sequences for the 7.68Mcps TDD option are unique to the modulation sequences for the 3.84Mcps TDD option.
The modulated secondary SCH codes are also constructed such that their cyclic-shifts are unique, i.e. a non-zero cyclic shift less than 2 (Case 1) and 4 (Case 2) of any of the sequences is not equivalent to some cyclic shift of any other of the sequences. Also, a non-zero cyclic shift less than 2 (Case 1) and 4 (Case 2) of any of the sequences is not equivalent to itself with any other cyclic shift less than 8. The secondary synchronization codes are partitioned into two code sets for Case 1 and four code sets for Case 2. The set is used to provide the following information:
Case 1:
Table 7A: Code Set Allocation for Case 1
|
Code Set |
Code Group |
|
1 |
0-15 |
|
2 |
16-31 |
The code group and frame position information is provided by modulating the secondary codes in the code set.
Case 2:
Table 7B: Code Set Allocation for Case 2
|
Code Set |
Code Group |
|
1 |
0-7 |
|
2 |
8-15 |
|
3 |
16-23 |
|
4 |
24-31 |
The slot timing and frame position information is provided by the comma free property of the code word and the Code group is provided by modulating some of the secondary codes in the code set.
The following SCH codes are allocated for each code set:
Case 1
Code set 1: C1, C3, C5.
Code set 2: C10, C13, C14.
Case 2
Code set 1: C1, C3, C5.
Code set 2: C10, C13, C14.
Code set 3: C0, C6, C12.
Code set 4: C4, C8, C15.
The following subclauses 7A.2.1 to 7A.2.2 refer to the two cases of SCH/P-CCPCH usage as described in [7].
Note that in the tables 7C and 7D corresponding to Cases 1 and 2, respectively, Frame 1 implies the frame with an odd SFN and Frame 2 implies the frame with an even SFN.
7A.2.1 Code allocation for Case 1
Table 7D: Code Allocation for Case 1
|
Code Group |
Code Set |
Frame 1 |
Frame 2 |
Associated toffset |
||||
|
0 |
1 |
C1 |
C3 |
jC5 |
C1 |
C3 |
-jC5 |
t0 |
|
1 |
1 |
C1 |
-C3 |
jC5 |
C1 |
-C3 |
-jC5 |
t1 |
|
2 |
1 |
-C1 |
C3 |
jC5 |
-C1 |
C3 |
-jC5 |
t2 |
|
3 |
1 |
-C1 |
-C3 |
jC5 |
-C1 |
-C3 |
-jC5 |
t3 |
|
4 |
1 |
jC1 |
jC3 |
jC5 |
jC1 |
jC3 |
-jC5 |
t4 |
|
5 |
1 |
jC1 |
-jC3 |
jC5 |
jC1 |
-jC3 |
-jC5 |
t5 |
|
6 |
1 |
-jC1 |
jC3 |
jC5 |
-jC1 |
jC3 |
-jC5 |
t6 |
|
7 |
1 |
-jC1 |
-jC3 |
jC5 |
-jC1 |
-jC3 |
-jC5 |
t7 |
|
8 |
1 |
jC1 |
C5 |
C3 |
jC1 |
C5 |
-C3 |
t8 |
|
9 |
1 |
jC1 |
-C5 |
C3 |
jC1 |
-C5 |
-C3 |
t9 |
|
10 |
1 |
-jC1 |
C5 |
C3 |
-jC1 |
C5 |
-C3 |
t10 |
|
11 |
1 |
-jC1 |
-C5 |
C3 |
-jC1 |
-C5 |
-C3 |
t11 |
|
12 |
1 |
jC3 |
C5 |
C1 |
jC3 |
C5 |
-C1 |
t12 |
|
13 |
1 |
jC3 |
-C5 |
C1 |
jC3 |
-C5 |
-C1 |
t13 |
|
14 |
1 |
-jC3 |
C5 |
C1 |
-jC3 |
C5 |
-C1 |
t14 |
|
15 |
1 |
-jC3 |
-C5 |
C1 |
-jC3 |
-C5 |
-C1 |
t15 |
|
16 |
2 |
C10 |
C13 |
jC14 |
C10 |
C13 |
-jC14 |
t16 |
|
17 |
2 |
C10 |
-C13 |
jC14 |
C10 |
-C13 |
-jC14 |
t17 |
|
|
|
|
|
|
|
|
|
|
|
20 |
2 |
jC10 |
jC13 |
jC14 |
jC10 |
jC13 |
-jC14 |
t20 |
|
|
|
|
|
|
|
|
|
|
|
24 |
2 |
jC10 |
C14 |
C13 |
jC10 |
C14 |
-C13 |
t24 |
|
|
|
|
|
|
|
|
|
|
|
31 |
2 |
-jC13 |
-C14 |
C10 |
-jC13 |
-C14 |
-C10 |
t31 |
NOTE: The code construction for code groups 0 to 15 using only the SCH codes from code set 1 is shown. The construction for code groups 16 to 31 using the SCH codes from code set 2 is done in the same way.
7A.2.2 Code allocation for Case 2
Table 7C: Code Allocation for Case 2
|
Code Group |
Code Set |
Frame 1 |
Frame 2 |
Associated toffset |
||||||||||
|
Slot k |
Slot k+8 |
Slot k |
Slot k+8 |
|||||||||||
|
0 |
1 |
C1 |
C3 |
jC5 |
C1 |
C3 |
-jC5 |
-C1 |
-C3 |
jC5 |
-C1 |
-C3 |
-jC5 |
t0 |
|
1 |
1 |
C1 |
-C3 |
jC5 |
C1 |
-C3 |
-jC5 |
-C1 |
C3 |
jC5 |
-C1 |
C3 |
-jC5 |
t1 |
|
2 |
1 |
jC1 |
jC3 |
jC5 |
jC1 |
jC3 |
-jC5 |
-jC1 |
-jC3 |
jC5 |
-jC1 |
-jC3 |
-jC5 |
t2 |
|
3 |
1 |
jC1 |
-jC3 |
jC5 |
jC1 |
-jC3 |
-jC5 |
-jC1 |
jC3 |
jC5 |
-jC1 |
jC3 |
-jC5 |
t3 |
|
4 |
1 |
jC1 |
C5 |
C3 |
jC1 |
C5 |
-C3 |
-jC1 |
-C5 |
C3 |
-jC1 |
-C5 |
-C3 |
t4 |
|
5 |
1 |
jC1 |
-C5 |
C3 |
jC1 |
-C5 |
-C3 |
-jC1 |
C5 |
C3 |
-jC1 |
C5 |
-C3 |
t5 |
|
6 |
1 |
jC3 |
C5 |
C1 |
jC3 |
C5 |
-C1 |
-jC3 |
-C5 |
C1 |
-jC3 |
-C5 |
-C1 |
t6 |
|
7 |
1 |
jC3 |
-C5 |
C1 |
jC3 |
-C5 |
-C1 |
-jC3 |
C5 |
C1 |
-jC3 |
C5 |
-C1 |
t7 |
|
8 |
2 |
C10 |
C13 |
jC14 |
C10 |
C13 |
-jC14 |
-C10 |
-C13 |
jC14 |
-C10 |
-C13 |
-jC14 |
t8 |
|
9 |
2 |
C10 |
-C13 |
jC14 |
C10 |
-C13 |
-jC14 |
-C10 |
C13 |
jC14 |
-C10 |
C13 |
-jC14 |
t9 |
|
10 |
2 |
jC10 |
jC13 |
jC14 |
jC10 |
jC13 |
-jC14 |
-jC10 |
-jC13 |
jC14 |
-jC10 |
-jC13 |
-jC14 |
t10 |
|
11 |
2 |
jC10 |
-jC13 |
jC14 |
jC10 |
-jC13 |
-jC14 |
-jC10 |
jC13 |
jC14 |
-jC10 |
jC13 |
-jC14 |
t11 |
|
12 |
2 |
jC10 |
C14 |
C13 |
jC10 |
C14 |
-C13 |
-jC10 |
-C14 |
C13 |
-jC10 |
-C14 |
-C13 |
t12 |
|
13 |
2 |
jC10 |
-C14 |
C13 |
jC10 |
-C14 |
-C13 |
-jC10 |
C14 |
C13 |
-jC10 |
C14 |
-C13 |
t13 |
|
14 |
2 |
jC13 |
C14 |
C10 |
jC13 |
C14 |
-C10 |
-jC13 |
-C14 |
C10 |
-jC13 |
-C14 |
-C10 |
t14 |
|
15 |
2 |
jC13 |
-C14 |
C10 |
jC13 |
-C14 |
-C10 |
-jC13 |
C14 |
C10 |
-jC13 |
C14 |
-C10 |
t15 |
|
16 |
3 |
C0 |
C6 |
jC12 |
C0 |
C6 |
-jC12 |
-C0 |
-C6 |
jC12 |
-C0 |
-C6 |
-jC12 |
t16 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
23 |
3 |
jC6 |
-C12 |
C0 |
jC6 |
-C12 |
-C0 |
-jC6 |
C12 |
C0 |
-jC6 |
C12 |
-C0 |
t20 |
|
24 |
4 |
C4 |
C8 |
jC15 |
C4 |
C8 |
-jC15 |
-C4 |
-C8 |
jC15 |
-C4 |
-C8 |
-jC15 |
t24 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
31 |
4 |
jC8 |
-C15 |
C4 |
jC8 |
-C15 |
-C4 |
-jC8 |
C15 |
C4 |
-jC8 |
C15 |
-C4 |
t31 |
NOTE: The code construction for code groups 0 to 15 using the SCH codes from code sets 1 and 2 is shown. The construction for code groups 16 to 31 using the SCH codes from code sets 3 and 4 is done in the same way.
7A.3 Evaluation of synchronisation codes
The evaluation of information transmitted in SCH on code group and frame timing is shown in table 7E, where the 32 code groups are listed. Each code group contains 4 specific scrambling codes, each scrambling code associated with a specific short and long basic midamble code.
Each code group is additionally linked to a specific tOffset, thus to a specific frame timing. By using this scheme, the UE can derive the position of the frame border due to the position of the SCH sequence and the knowledge of tOffset. The complete mapping of Code Group to Scrambling Code, Midamble Codes and tOffset is depicted in table 7E.
Table 7E: Mapping scheme for Cell Parameters, Code Groups,
Scrambling Codes, Midambles and tOffset
|
CELL PARA-METER |
Code Group |
Associated Codes |
Associated tOffset |
||
|
Scrambling Code |
Long Basic Midamble Code |
Short Basic Midamble Code |
|||
|
0 |
Group 0 |
Code 0 |
mPL0 |
mSL0 |
t0 |
|
1 |
Code 1 |
mPL1 |
mSL1 |
||
|
2 |
Code 2 |
mPL2 |
mSL2 |
||
|
3 |
Code 3 |
mPL3 |
mSL3 |
||
|
4 |
Group 1 |
Code 4 |
mPL4 |
mSL4 |
t1 |
|
5 |
Code 5 |
mPL5 |
mSL5 |
||
|
6 |
Code 6 |
mPL6 |
mSL6 |
||
|
7 |
Code 7 |
mPL7 |
mSL7 |
||
|
. . . . |
|||||
|
124 |
Group 31 |
Code 124 |
mPL124 |
mSL124 |
t31 |
|
125 |
Code 125 |
mPL125 |
mSL125 |
||
|
126 |
Code 126 |
mPL126 |
mSL126 |
||
|
127 |
Code 127 |
mPL127 |
mSL127 |
||
Each cell shall cycle through two sets of cell parameters in a code group with the cell parameters changing each frame. Table 7F shows how the cell parameters are cycled according to the SFN.
Table 7F: Alignment of cell parameter cycling and SFN
|
Initial Cell Parameter Assignment |
Code Group |
Cell Parameter used when SFN mod 2 = 0 |
Cell Parameter used when SFN mod 2 = 1 |
|
0 |
Group 0 |
0 |
1 |
|
1 |
1 |
0 |
|
|
2 |
2 |
3 |
|
|
3 |
3 |
2 |
|
|
4 |
Group 1 |
4 |
5 |
|
5 |
5 |
4 |
|
|
6 |
6 |
7 |
|
|
7 |
7 |
6 |
|
|
. . . . |
|||
|
124 |
Group 31 |
124 |
125 |
|
125 |
125 |
124 |
|
|
126 |
126 |
127 |
|
|
127 |
127 |
126 |
|