Product Info

1X UBS Macro B T S FRU XMI (T r ansceiv er Module Internal) Module
XPAC Functions
The XMI P A Controller (XP AC) communicates with the XMI processor and controls/monitors
the following XMI circuits:
• 3 -sector TX RF output FTM.
• Three multi -carrier TX RF LP A sections; one LP A section for each sector .
• Five cooling fans in the fan tray mounted on the rear of the XMI.
The XP AC and the XMI processor exchange control data and status/alarm messages via a
dedicated serial bus. The XP AC collects status/alarm inputs from each sector TX RF LP A, each
cooling fan and the TX RF output FTM. Then the XP AC reports this status/alarm information in
data messages to the XMI processor .
The output FTM detects forward/reverse power of each sector TX RF output and reports it to
the XP AC . If something like a sector antenna path with an extreme impedance mismatch causes
abnormal detected forward/reverse power , the XP AC will signal the respective FTM RF coaxial
switch relay to open the switch and block the sector TX RF output signal.
Each sector TX RF LP A has phase and power level sensors/controls throughout the LP A signal
path that the XP AC uses to dynamically increase/decrease the phase and power level of the
sector TX RF output signal as needed.
The XP AC monitors XMI and P A heatsink temperatures as well as the speed (T ACH) of each of
the five cooling fans. The XP AC sends a Pulse -W idth Modulated (PWM) DC control signal to
each fan to increase/decrease fan speed as needed to provide proper cooling.
System Impact/Considerations
P erforming this replacement procedure in a UBS Macro frame with one XMI will
cause BTS downtime and suspend all BTS call processing.
P erforming this replacement procedure in a UBS Macro frame with more than one
XMI will not cause BTS downtime, but will reduce BTS call processing capacity .
In the UBS Macro frame with one XMI, removal of the XMI has the following effects:
• Interrupts the Main and Diversity RX signal paths for all sectors.
• Interrupts TX RF output power on all sectors.
In the UBS Macro frame with more than one XMI: If XMI 1 is removed, the Main RX signal path
is interrupted for all sectors. If XMI 2 is removed, the Diversity RX signal path is interrupted
for all sectors.
68P09283A64 -3 7 -7
FOA SEP 2007