User Manual
PN Offset
68P09255A57-2
Aug 2002
SC4812ET Optimization/ATP Manual Software Release R16.1.x.x
PRELIMINARY
E-2
PN Offset
Background
All channel elements transmitted from a BTS in a particular 1.25 MHz
CDMA channel are orthonogonally spread by 1 of 64 possible Walsh
code functions; additionally, they are also spread by a quadrature pair of
PN sequences unique to each sector.
Overall, the mobile uses this to differentiate multiple signals transmitted
from the same BTS (and surrounding BTS) sectors, and to synchronize
to the next strongest sector.
The PN offset per sector is stored on the BBXs, where the
corresponding I & Q registers reside.
The PN offset values are determined on a per BTS/per sector(antenna)
basis as determined by the appropriate cdf file content. A breakdown of
this information is found in Table E-1.
Usage
There are three basic RF chip delays currently in use. It is important to
determine what RF chip delay is valid to be able to test the BTS
functionality. This can be done by ascertaining if the CDF file
FineTxAdj value was set to “on” when the MCC was downloaded with
“image data”. The
FineTxAdj value is used to compensate for the
processing delay (approximately 20 mS) in the BTS using any type of
mobile meeting IS-97 specifications.
Observe the following guidelines:
If the FineTxAdj value in the cdf file is 101 (65 HEX), the
FineTxAdj has not been set. The I and Q values from the 0 table
MUST be used.
If the
FineTxAdj value in the cdf file is 213 (D5 HEX), FineTxAdj has
been set for the 14 chip table.
If the FineTxAdj value in the cdf file is 197 (C5 HEX), FineTxAdj
has been set for the 13 chip table.
NOTE
CDF file I and Q values can be represented in DECIMAL or
HEX. If using HEX, add 0x before the HEX value. If necessary,
convert HEX values in Table E-1 to decimal before comparing
them to cdf file I & Q value assignments.
- If you are using a Qualcomm mobile, use the I and Q values from
the 13 chip delay table.
- If you are using a mobile that does not have the 1 chip offset
problem, (any mobile meeting the IS-97 specification), use the 14
chip delay table.
NOTE
If the wrong I and Q values are used with the wrong
FineTxAdj parameter, system timing problems will occur. This
will cause the energy transmitted to be “smeared” over several
Walsh codes (instead of the single Walsh code that it was
assigned to), causing erratic operation. Evidence of smearing is
usually identified by Walsh channels not at correct levels or
present when not selected in the Code Domain Power Test.
E