User Manual

Software descrIption
Nortel Networks Confidential
4–10
PE/DCL/DD/0063
411–9001–063
Standard 12.07/EN September 2000
GSM/BSS V12
L3 TX
This software unit manages and monitors radio transmission. It is installed in each
DRX board. It sets the transmitter operation mode, defines the FH bus input from
which the TX should read data, and defines the transmission power to be used. It
also forwards TX alarms to the CSWM and controls the Power Amplifier (PA).
L1 BDT
This software unit extracts the GSM TIME carried on the PCMp (GSM TIME TS)
for the BDT unit.
LAPD
This software unit manages the LAPD link level 2 protocol on PCM between DRX
and BSC.
L1 O&M, L2 O&M
These software units manage the link level 1 & 2 protocol on private PCMs between
DRX and CSWM.
4.2.1.1 Defense
The DRX (or e–DRX) board carries out no defense actions by itself.
4.2.2 BCF software functions
The Base Common Functions unit (BCF) is located in the cabinet. It is downloaded
by the BSC, it provides the interface between the BTS and its Base Station
Controller (BSC). It also handles the following functions:
It sets the signaling channel and physical path concentration.
It generates and distributes the GSM time to all BTS units.
It monitors and detects all BTS alarms.
It correlates some BTS alarms in order to provide to the BSC a logical state of the
BTS, by using the event reporting procedure. The DRX is still monitored partly
by the BCF (TX) and partly by the DRX (AMNU/SPU).
It provides local protection of some BTS modules, by implementing redundant
equipment units.
Synchronization unit level 3 layer (L3–SYN)
This software unit is installed in each synchronization unit. It monitors
synchronization board switching, and sends a message to the CSWM whenever
switching occurs.