Rohde & Schwarz SMIQ02B - PN Generators as Internal Data Source; Table 2-17 PN Generators for W-CDMA

SMIQ Digital Standard W-CDMA (NTT DoCoMo/ARIB 0.0)
1125.5555.03 E-92.153
2.13.2 PN Generators as Internal Data Source
Different PN (Pseudo Noise) generators can be selected as data source for DATA fields. These PN
generators provide pseudo random bit sequences of different lengths or periods which is why they are
also called PRBS generators (Pseudo R
andom Binary Sequence).
The data sequences are so-called sequences of maximum lengths that are generated by means of
feedback shift registers.
The following schematic shows the 9 bit generator with feedback to registers 4 and 0 (output).
8
765 4 3
2
10
DATA
EXOR
The pseudo random sequence of a PRBS generator is determined by the number of registers and the
feedback. The following table describes all available PRBS generators:
Table 2-17 PN generators for W-CDMA
PRBS generator Length in bits Feedback to Start value (*)
9 bits 2
9
-1 = 511 Register 4, 0 Channel 0: 0000 0100 1
Channel 1: 1000 0100 1
Channel 2: 0100 0100 1
Channel 3: 1100 0100 1
...
Channel 15: 1111 0100 1
11 bits 2
11
-1 =2047 Register 2, 0 Channel 0: 0000 0100 100
...
Channel 15: 1111 0100 100
15 bits 2
15
-1 = 32767 Register 1, 0 Channel 0: 0000 0100 1000 000
...
Channel 15: 1111 0100 1000 000
16 bits 2
16
-1 = 65535 Register 5, 3, 2, 0 Channel 0: 0000 0100 1000 0000
...
Channel 15: 1111 0100 1000 0000
*) the 5th start value bit of channels in Q phase is 1 (for example: channel 3: 1100 1100 1...)
PN generators PN9,11 and PN15 are designed according to CCITT Rec. 0.151/152/153. The output
sequence is inverted for generator PN15.
Example: PN9 generator in channel 3 with start value 110001001 (binary)
11
DATA
EXOR
0001 0 0 1
The resulting output sequence is 110001001100010001000 etc.