
Chapter 6 197
BERT Testing
RF Loopback BER–Option 300
during synchronization to the BTS and during measurements.
GSM Transmit Data
The minimum GSM transmit data requirements for the loopback test are a fully GSM-coded
26-channel multiframe with either PN9 or PN15 in the payload. This is selected on the ESG
by setting the timeslot under test to normal and selecting the PN9 or PN15 multiframe PN
pattern.
To meet the GSM standards requirements for full conformance, the adjacent timeslots should
be loaded with fully GSM-coded data. The ESG offers full flexibility of loading all timeslots.
Edge Frame Structure
52-frame PDCH multiframe structure.
Frames: 12 blocks of 4 frames, 2 idle frames, and 2 frames used for the PTCCH.
Table 6-1 GSM Received Data
During BCH Synchronization
TS0 51-frame BCH Multiframe Structure
SCH in frames 1, 11, 21, 31, 41
TS1-7 No SCH, but otherwise, don’t care
During TCH Synchronization
TSX 26-frame TCH Multiframe Structure
Frame 25 idle
Frame 12 don’t care
Other frames TCH
During Measurements
Timeslot under
test
26-frame full-rate voice TCH Multiframe Structure
TCH
Frames 0-11,
13-24
Content determined by transmitted signal (looped by BTS
except for errored speech frames, i.e. speech frames with
bad CRC)
Frames 12, 25 Don’t care
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