5A.2.2 8PSK modulation

25.2233GPPRelease 17Spreading and modulation (TDD)TS

The data modulation is performed to the bits from the output of the physical channel mapping procedure. In case of 8PSK modulation 3 consecutive binary bits are represented by one complex valued data symbol. Each user burst has two data carrying parts, termed data blocks:

(1a)

N_k is the number of symbols per data field for the code k. This number is linked to the spreading factor Q_k.

Data block is transmitted before the midamble and data block after the midamble. Each of the N_k data symbols ; i=1, 2; k=1,…,K_Code; n=1,…,N_k; of equation 1 has the symbol duration as already given.

The data modulation is 8PSK, thus the data symbols are generated from 3 consecutive data bits from the output of the physical channel mapping procedure in [8]:

(2a)

using the following mapping to complex symbols:

Consecutive binary bit pattern	complex symbol
000	cos(11pi/8)+ jsin(11pi/8)
001	cos(9pi/8)+ jsin(9pi/8)
010	cos(5pi/8)+ jsin(5pi/8)
011	cos(7pi/8)+ jsin(7pi/8)
100	cos(13pi/8)+ jsin(13pi/8)
101	cos(15pi/8)+ jsin(15pi/8)
110	cos(3pi/8)+ jsin(3pi/8)
111	cos(pi/8)+ jsin(pi/8)

The mapping corresponds to a 8PSK modulation of the interleaved and encoded data bits of the table above and of equation 1a.