Chapter 2
GSM Call Mode Operation
GSM tests
64
4460 GSM System Option and 4468 EDGE System Option
Version 12.20
Residual BER Live Display
The RBER is the
R
esidual
B
it
E
rror
R
atio. This is very similar to the standard BER
with the following exception:
If the channel decoder of the mobile detects a bad frame, the mobile will ignore
the entire frame and signal that back to the 4400 (with a frame containing zeros
for the speech block only).
The 4400 will just count how many frames the mobile rejects and will not use
the bad frames for calculating the BER. In short words, a RBER is a BER measure-
ment on those frames only that are accepted by the mobile.
How to read the RBER results display
Curr.
Fast BER of the current test run. Please see section
“Statis-
tical test evaluation”
for details.
Min.
Smallest Fast BER of all test runs. Please see section
“Sta-
tistical test evaluation”
for details.
Avg.
Average Fast BER of all test runs. Please see section
“Sta-
tistical test evaluation”
for details.
Max.
Largest Fast BER of all test runs. Please see section
“Statis-
tical test evaluation”
for details.
Round trip
delay
The round-trip delay is the number of TDMA frames
between the reception of a particular burst at the mobile
and the transmission of the same burst (on the uplink).
As there is no coding and encoding required on the
mobile’s side, just the loop-back of the data received, the
typical round-trip delay in Fast BER is one frame.
Counter
Bits
The figure shown in line FER gives the number of voice
blocks used for testing.
The numbers indicated in lines Ib and II show the total
amount of the class Ib and class II bits that were used to
calculate the RBER test results.