6.4 Scrambling codes for the 3.84Mcps and 1.28Mcps options
25.2233GPPRelease 17Spreading and modulation (TDD)TS
The spreading of data by a real valued channelisation code 
of length Qk is followed by a cell specific complex scrambling sequence 
. The elements 
of the complex valued scrambling codes shall be taken from the complex set
(4)
In equation 4 the letter j denotes the imaginary unit. A complex scrambling code 
is generated from the binary scrambling codes 
of length 16 shown in Annex A. The relation between the elements 
and 
is given by:
(5)
Hence, the elements 
of the complex scrambling code 
are alternating real and imaginary.
The length matching is obtained by concatenating QMAX/Qk spread words before the scrambling. The scheme is illustrated in figure 2 and is described in more detail in subclause 6.5.
Figure 2: Spreading of data symbols