BTS Antenna System Monitor Manual Guide

How to supervise antenna systems without VSWR?

• There is a new function called ”Antenna system monitor”(ASM) that supervises antennas.
• The main differences between VSWR and ASM is that VSWR uses dedicated harware that operate on the TX branches while ASM is a software implementation that operates on regular traffic’s RX signals.

 

 

Availability

• ASM is implemented in BBS release 07A.
• The possibility to use ASM on earlier releases is under investigation. Some kind of upgrade will be needed since the new alarms call for new A”messages.

ASM Alarms

• RBS to supervise the average valueduring a sliding window time of x minutes, and report a Class 1or a Class 2fault if presetted limits are exceeded : 

• Class 1 fault (AO TX I1B) mapped on faulty TX Antenna -> BSC closes down the failing TX,

• Class 2 fault (AO RX I2A) mapped on faulty RX Antenna -> Reported on a fault list.

Parameters, Controlled from OMT

OMTSW : Define four presetable supervision limit parameters 

• Average Class 1 and 2 limit (Class 1 Default : OFF, Class 2 Default : 6 dB),

• Window Time for supervision (Default: 24h),

• Number of Samples ( Default : 7200 )

• Via OMT it is possible to monitor measured values installed by RBS SW, which are compared with these limits during supervision)

Dependencies and Limitations

• ASM doesn’t cover TX-only antennas,
• Slow in detecting antenna faults (compared with VSWR), as statistical calculation over minutes to hours needed to detect a failure,
• Measurements will use TCH timeslots,
• Restart needed after change of parameters.