Rx Path Imbalance

[bikplaboi]

Hi All,

Could people tell what possible issues can cause RF Path Imbalance problems on a cell??

I know feeder sweep is a good troubleshooting possibility but is there anything else I need to try should the feed sweep test result be OKAY.

I thank all who contribute to this thread in advance thanks so much...



Cheers,

bikplaboi

[charommel]

hi, in cases where you use Space diversity Antennas, there are cases when the azimuth or tilt are not the same for the RX and TX antennas. If you have overshooting coverage, this could also cause this problem. thanks.


Hi All,

Could people tell what possible issues can cause RF Path Imbalance problems on a cell??

I know feeder sweep is a good troubleshooting possibility but is there anything else I need to try should the feed sweep test result be OKAY.

I thank all who contribute to this thread in advance thanks so much...



Cheers,

bikplaboi

[Piscean21]

You should check for BTS output power as well.increase in power results in increase in coverage and makes DL stronger.

[s52d]

hi, in cases where you use Space diversity Antennas, there are cases when the azimuth or tilt are not the same for the RX and TX antennas. If you have overshooting coverage, this could also cause this problem. thanks.

I guess "Rx Path Imbalance" indicates you use two receivers, but most of
RX is stronger on one.

Beside faulty antenna:
Is there something in front of antenna? Chimney, competitor tower, anything metal?

Faulty antenna preamplifier? Any unit in base station specific for TX or RX only?
Water in the second cable used only for RX?
Can you measure VSWR on both antennas?


BR
s52d

[kvf]

In E/// fault list I found following:

This fault occurs together with a pinpointed antenna, if the difference in signal strength between two antennas in the same antenna system exceeds the limits defined using the OMT function Define RX Path Imbalance Parameters. If the class 1 limit is exceeded, the related fault AO TX I1B:35 is also issued and the TX will be disabled.
The supervision of this fault is based on measurements over a long time duration, hence the fault does not cease as soon as the fault condition is corrected. The RX imbalance monitor must therefore be used to verify the correction of the fault condition.
When the fault condition has been corrected, reset the TRU to cause the fault to terminate immediately.
Observe, If the fault condition was not corrected, the fault will be reported again when at least the minimum number of samples has been collected. The minimum number of samples is defined by the Define RX Path Imbalance Parameters function in the OMT.
Follow the instructions below until the fault is corrected:
-Check the defined RX path invariance limits using the Define RX Path Imbalance Parameters function in the OMT for the faulty antenna system.
-Check the TX cables/feeders, cable connections inside and outside the cabinet and antennas, for example with Antenna System SWR tests. For information about how to perform a SWR test see Verifying Antenna Systems or Antenna System Tests in the CPI for the relevant RBS.
-Reset the TRU



Hi All,

Could people tell what possible issues can cause RF Path Imbalance problems on a cell??

I know feeder sweep is a good troubleshooting possibility but is there anything else I need to try should the feed sweep test result be OKAY.

I thank all who contribute to this thread in advance thanks so much...



Cheers,

bikplaboi

[gprastomo]

Hi Path Balance that i found usually imbalance between UL coverage and DL coverage.
This problem make alot of degradation especially in incoming HO and Call Setup, why because you have good DL coverage but when u try to access, you ll fail because the UL side will never reach the BTS sensitivity.
Usually the problem appear on UL imbalance, if DL problem, the problem wont be so bad.
Usually UL and DL path difference is about 4-5 dB, UL will have less coverage.
You can try to list the DL and UL RXLevel difference per TRX then sort descending order, then you ll find the highest Path difference if it is about 5 dB so forget it, if it is 10 dB different so you have path balance problem.
Usually in Tems, it will show maximum UE txPOwer even near the cell.

Usually the problem is on the combiner (high loss on UL side) or antenna which only on receiving path, etc

br


Hi All,

Could people tell what possible issues can cause RF Path Imbalance problems on a cell??

I know feeder sweep is a good troubleshooting possibility but is there anything else I need to try should the feed sweep test result be OKAY.

I thank all who contribute to this thread in advance thanks so much...



Cheers,

bikplaboi