Technical data

Chapter 20 577
W-CDMA or W-CDMA (with HSDPA) Over Air
Using the W-CDMA or W-CDMA (with HSDPA) Over the Air Tool
W-CDMA or W-CDMA (with HSDPA)
Over Air
CAUTION To achieve valid over-the-air measurements, the test set must be stationary (not
moving). An alternative is to make these measurements from a coupled port at the
base station.
Preparing to Make W-CDMA or W-CDMA (with HSDPA) Over
the Air Measurements
An important consideration when making W-CDMA or W-CDMA (with HSDPA)
over the air measurements is your location relative to the base station. There must be
no obstructions between your location and the base station antennas. Also, the GPS
antenna must be able to “see” the satellites to obtain lock. You must know the
channel or frequency and the Channel Standard of the W-CDMA or W-CDMA
(with HSDPA) signal to be analyzed.
Once you have connected the proper antenna and filter to the test set, chosen a
stationary location, and verified that you have a clear view of the base station
antennas, you can perform W-CDMA or W-CDMA (with HSDPA) over the air
measurements.
If this is the first W-CDMA or W-CDMA (with HSDPA) over the air measurement
for this base station, you must find a location that meets the criteria for making a
valid measurement. Your location must have a dominant pilot and very low
multipath power. If you have made W-CDMA or W-CDMA (with HSDPA) over the
air measurements at this location before and know it provides valid measurements,
skip to “Performing a Basic Over the Air Measurement” on page 579.
Criteria for Making Valid Over the Air Measurements
The first step in making valid W-CDMA (with or without HSDPA) over the air
measurements is to identify a target base station to measure. Then, for your
measurements to be valid, you must find a location near the target base station with
an unobstructed view of the base station antenna and a sufficiently strong W-CDMA
or W-CDMA (with HSDPA) signal. W-CDMA or W-CDMA (with HSDPA) over
the air measurements will experience interference from other W-CDMA or
W-CDMA (with HSDPA) signals on the same RF channel and from multipath
echoes. The code domain power view measures two key parameters to indicate these
effects:
• Pilot dominance—The difference between the useful energy of the strongest
pilot channel and the combined energy of the lower energy active pilot channels
(expressed in dB). Ideally, this value should be very large (> 18 dB).