User Manual

Architecture
Nortel Networks Confidential
3–22
PE/DCL/DD/0063
411–9001–063
Standard 12.07/EN September 2000
GSM/BSS V12
The last two events are fed back to the CSWM. Defense actions are covered in
section dedicated to the CSWM.
In case of a synchronization unit fault, the synchronization units make the
switchover decision (active <=> standby). The fault is then fed back to the CSWM
over the O&M bus.
3.2.5 Alarm collecting function (ALCO)
3.2.5.1 Functions
The alarm collecting board (ALCO), located outside the BCF, collects internal and
external BTS alarms.
Internal alarms concern equipment parts on which the BCF does not use any
particular detection action, while external alarms are site–dependent.
These alarms are sent via the O&M bus to the BCF control unit, which redirects
them to the BSC.
The board also allows equipment located outside the BTS to be activated (future
use).
3.2.6 BCF/DRX gateway (GTW)
The gateway (GTW) carries out the following functions (see Figure 3–6):
adaptation of the frequency between the radio interface and the Abis interface
adaptation of the GSM TIME bus to the GSM TIME channel
adaptation of the O&M bus to the O&M channel for the TXs
management of the O&M protocol for the gateway as an O&M slave
management of part of the defense system
management of part of the switchover logic
initialization of the gateway board
3.2.6.1 Adaptation of the GSM TIME bus to the GSM TIME channel
This function consists in entering the GSM time on the GSM TIME bus, then
making calculations and carrying out formating to send the GSM time to the DRXs
by means of the GSM TIME channel.
3.2.6.2 Adaptation of the O&M bus to the O&M channel
This function consists in decoding the validation on the O&M bus of a dialogue
between the CSWM and the TX, and formating the characters sent and received on
the bus and the O&M channel.