Technical data

Chapter 20 613
W-CDMA or W-CDMA (with HSDPA) Over Air
Interpretation of Over the Air Measurement Results
W-CDMA or W-CDMA (with HSDPA)
Over Air
to position the test set. If the correct Scrambling code cannot be located, check the
base station settings.
Noise Floor
An unexpectedly high noise floor could be due to interfering signals.
If you have not already done so, you can reduce the noise floor by activating the IF
Equalizer (See “Setting the IF Equalizer” on page 605.)
Carr Feedthru (Carrier Feedthrough)
A good Carrier Feedthrough level is less than -25 dBc. The 3GPP standard does not
specify Carrier Feedthrough; however, this measurement provides an additional tool
to troubleshoot the base station's transmitter.
In the frequency domain, Carrier Feedthrough can show up as an energy spike that
can be seen on the spectrum analyzer by closely spanning into the top of the
W-CDMA or W-CDMA (with HSDPA) signal. The effects of Carrier Feedthrough
can also show up as higher noise levels on the Code Domain Power screen. Carrier
Feedthrough can be caused by the lack of isolation across the mixer and cavity of
the transmitter's I/Q modulator.
EVM Pilot and EVM Comp (Pilot (CPICH) and Composite Error Vector
Magnitude
An unexpectedly high EVM could be due to interfering signals, carrier feedthrough,
transmitter I/Q modulator, or signal path problems.
If you have not already done so, you can reduce the noise floor by activating the IF
Equalizer (See “Setting the IF Equalizer” on page 605.)
PCDE (Peak Code Domain Error)
An unexpectedly high PCDE could be due to interfering signals, carrier
feedthrough, pilot dominance, or multipath power. If these are all correct, check for
transmitter I/Q modulator or signal path problems.
Utilization
The Utilization metric provides an instantaneous reading of the percentage of the
traffic channels currently being used. More meaningful information is provided by
the Peak and Average Utilization metrics gathered over a 10 to 15 minute interval.
Pk Util (Peak Utilization)
If the Peak Utilization of this base station is greater than 65%, this is a warning that