6.4a Scrambling codes for the 7.68Mcps option
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
(4a)
In equation 4a the letter j denotes the imaginary unit. A complex scrambling code 
is generated from the binary scrambling codes of length 32 that are generated according to the method described in section 6.4a.1. The relation between the elements 
and 
is given by:
(5a)
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.
6.4a.1 Generation of binary scrambling codes
The binary scrambling code, , for cell parameter n in the 7.68Mcps TDD option is formed from the concatenation of the binary scrambling codes and shown in Annex A: