8 Synchronisation codes for the 1.28 Mcps option
25.2233GPPRelease 17Spreading and modulation (TDD)TS
8.1 The downlink pilot channel (DwPCH)
The contents of DwPCH is composed of 64 chips of a SYNC-DL sequence, cf.[AA.1 Basic SYNC-DL sequence] and 32 chips of guard period (GP). The SYNC-DL code is not scrambled
There should be 32 different basic SYNC-DL codes for the whole system.
For the generation of the complex valued SYNC-DL codes of length 64, the basic binary SYNC-DL codes 
of length 64 shown in Table AA.1 are used. The relation between the elements 
and 
is given by:
(1)
Hence, the elements 
of the complex SYNC-DL code 
are alternating real and imaginary.
The SYNC-DL is QPSK modulated and the phase of the SYNC-DL is used to signal the presence of the P-CCPCH in the multi-frame of the resource units of code 
and 
in time slot #0.
8.1.1 Modulation of the SYNC-DL
The SYNC-DL sequences are modulated with respect to the midamble (m(1)) in time slot #0.
Four consecutive phases (phase quadruple) of the SYNC-DL are used to indicate the presence of the P-CCPCH in the following 4 sub-frames. In case the presence of a P-CCPCH is indicated, the next following sub-frame is the first sub-frame of the interleaving period. As QPSK is used for the modulation of the SYNC-DL, the phases 45, 135, 225, and 315° are used.
The total number of different phase quadruples is 2 (S1 and S2). A quadruple always starts with an even system frame number ((SFN mod 2) =0). Table 8 is showing the quadruples and their meaning.
Table 8: Sequences for the phase modulation for the SYNC-DL
|
Name |
Phase quadruple |
Meaning |
|
S1 |
135, 45, 225, 135 |
There is a P-CCPCH in the next 4 sub-frames |
|
S2 |
315, 225, 315, 45 |
There is no P-CCPCH in the next 4 sub-frames |
8.2 The uplink pilot channel (UpPCH)
The contents in UpPCH is composed of 128 chips of a SYNC-UL sequence, cf. [AA.2 Basic SYNC-UL sequence] and 32chips of guard period (GP) .The SYNC-UL code is not scrambled.
There should be 256 different basic SYNC-UL codes (see Table AA.2) for the whole system.
For the generation of the complex valued SYNC-UL codes of length 128, the basic binary SYNC-UL codes 
of length 128 shown in Table AA.2 are used. The relation between the elements 
and 
is given by:
(2)
Hence, the elements 
of the complex SYNC-UL code 
are alternating real and imaginary.
8.3 Code Allocation
Relationship between the SYNC-DL and SYNC-UL sequences, the scrambling codes and the midamble codes
|
Code Group |
Associated Codes |
|||
|
SYNC-DL ID |
SYNC-UL ID |
Scrambling Code ID |
Basic Midamble Code ID |
|
|
Group 1 |
0 |
0…7 |
0 |
0 |
|
1 |
1 |
|||
|
2 |
2 |
|||
|
3 |
3 |
|||
|
Group 2 |
1 |
8…15 |
4 |
4 |
|
5 |
5 |
|||
|
6 |
6 |
|||
|
7 |
7 |
|||
|
. . . |
||||
|
Group 32 |
31 |
248…255 |
124 |
124 |
|
125 |
125 |
|||
|
126 |
126 |
|||
|
127 |
127 |
|||
Note: In a multi-frequency cell, primary frequency and secondary frequency use the same scrambling code and basic midamble code.
8.3Aa Code Allocation
For the dedicated carrier MBSFN, the basic preamble codes are segemted into two groups, even group and odd group, and the Basic preamble Code is described in [7].
Relationship between the scrambling codes and the preamble codes
|
Code subgroup |
Associated Codes |
|||
|
PP,even group |
PP,odd group |
|||
|
Scrambling Code ID |
Basic preamble Code ID |
Scrambling Code ID |
Basic preamble Code ID |
|
|
Sub-g1 |
0 |
0 |
4 |
1 |
|
Sub-g2 |
8 |
2 |
12 |
3 |
|
Sub-g3 |
16 |
4 |
20 |
5 |
|
Sub-g4 |
24 |
6 |
28 |
7 |
|
. . . |
||||
|
Sub-g15 |
112 |
28 |
116 |
29 |
|
Sub-g16 |
120 |
30 |
124 |
31 |