5.2.1 Mapping for burst type 1 and 2
25.2233GPPRelease 17Spreading and modulation (TDD)TS
5.2.1.1 QPSK modulation
The data modulation is performed to the bits from the output of the physical channel mapping procedure in [8] and combines always 2 consecutive binary bits to a complex valued data symbol. Each user burst has two data carrying parts, termed data blocks:
(1)
KCode is the number of used codes in a time slot: for 3.84Mcps, max KCode =16; for 7.68Mcps, max KCode =32. Nk is the number of symbols per data field for the code k. This number is linked to the spreading factor Qk [7].
Data block 
is transmitted before the midamble and data block 
after the midamble. Each of the Nk data symbols 
; i=1, 2; k=1,…,KCode; n=1,…,Nk; of equation 1 has the symbol duration 
as already given.
The data modulation is QPSK, thus the data symbols 
are generated from two consecutive data bits from the output of the physical channel mapping procedure in [8]:
(2)
using the following mapping to complex symbols:
|
consecutive binary bit pattern |
complex symbol |
|
|
|
|
00 |
+j |
|
01 |
+1 |
|
10 |
-1 |
|
11 |
-j |
The mapping corresponds to a QPSK modulation of the interleaved and encoded data bits 
of equation 2.
5.2.1.2 16QAM modulation
The data modulation is performed to the bits from the output of the physical channel mapping procedure. In case of 16QAM, modulation 4 consecutive binary bits are represented by one complex valued data symbol. Each user burst has two data carrying parts, termed data blocks:
(2b)
Nk is the number of symbols per data field for the user k. This number is linked to the spreading factor Qk.
Data block 
is transmitted before the midamble and data block 
after the midamble. Each of the Nk data symbols 
; i=1, 2; k=1,…,K; n=1,…,Nk; of equation 2b has the symbol duration 
as already given.
The data modulation is 16QAM, thus the data symbols 
are generated from 4 consecutive data bits from the output of the physical channel mapping procedure in [8]:
(2c)
using the following mapping to complex symbols:
|
Consecutive binary bit pattern |
complex symbol |
|
|
|
|
0000 |
|
|
0001 |
|
|
0010 |
|
|
0011 |
|
|
0100 |
|
|
0101 |
|
|
0110 |
|
|
0111 |
|
|
1000 |
|
|
1001 |
|
|
1010 |
|
|
1011 |
|
|
1100 |
|
|
1101 |
|
|
1110 |
|
|
1111 |
The mapping corresponds to a 16QAM modulation of the interleaved and encoded data bits 
of the table above and 
of equation 2b.