Bad RTWP Levels, before and after RRU, feeders and antenna swapping..!!!

[aleon23]

Dears experts,

Please your help with ideas or suggestion in order to identify where the problem is, as next short summary:

Since one week ago in nodeB CAMPOCHINO sector Z increase to -60dBm, however sector X, Y & W keep RTWP under -70dBm, in this phase we determined block sector Z and result were that RTWP in sector X, Y & W decreased to normal values (around -100dBm), also the neighbors decreased RTWP levels (check picture below)

The first suggestion was change RRU of sector Z in CAMPPOCHINO and second suggestion was antenna swap, but it didn´t work for any case.

In the next picture, around 20:00 sector Z was block (RTWP decreased in all sectors)
Around 6:00 sector Z RRU swap (no changes after 9:00, peak hour in that zone)
Around 12:00 sector Z was block again (RTWP decreased in all sectors)
Around 20:00 sector Z antenna swap (no changes, RTWP keep increase)

We also cheked external interference, but nothing was found in spectrum analyzer, this is an strange behavior that cause bad RTWP but improve when we block sector Z.




Hope for your answer,

Best Regards

[elkador]

can't see your pics, but first guess would be cross feeder : your sector Z Tx is connected to sector X or Y. Hence creating high RTWP on X and Y.

Another solution : you've got a metallic obstruction near sector Z, which is reflecting signal towards X and Y...

Hope this helps...

[aleon23]

can't see your pics, but first guess would be cross feeder : your sector Z Tx is connected to sector X or Y. Hence creating high RTWP on X and Y.

Another solution : you've got a metallic obstruction near sector Z, which is reflecting signal towards X and Y...

Hope this helps...

Dear elkador,

RTWP.jpgAREA.jpgEUN.jpg

Thanks for your answer, no cross feeder, we have 4 RRUs for sector X,Y,Z&W, but sector Z&W are in cascade with one RRU because there is only 1 Wbbp, however we have near to nodeB a jail but the behavior is strange because this site has around one on air and recently the problem appeared. Attached is the pictures with more details.

About metallic obstruction I don't know but this site actually is a tower of 30 meters, and also is affecting to neighbors also, not only inner nodeb.

Any other solutions,

Best Regards

[umts99]

Possible Solution for RTWP

[Mdaf]

Do you have any repeater installed in sector z serving area? Faulty repeaters can do such a thing or wrong installation especially if the input/output antennas can see each other (positive feedback).
Because I get confused when you say antenna swap you mean new antenna installed or you did intentional cross between sector z and other sector in order to check that the problem is related to sector z or the serving area of sector z?

[oswe]

Another solution : you've got a metallic obstruction near sector Z, which is reflecting signal towards X and Y...

the obstruction is reflecting DL Z TX power to the UL in X and Y ???? ???????

[magno22]

123 123 123 1231 1123 213 123 123 1 3

[kevin_h811]

Hi Aleon23,

The problem is within the NodeB itself.

Check possible feeder,cables,etc. causing RTWP.Just use your common sense.

BR//

[Fado]

hi i guess you should check for external interference again, as jails are using jammers to avoid cell phone talks nearby or by inmates...they may use it in some special occasions too..you may direct other sectors' antenna to see if it happens in only that direction..

[Mdaf]

Hello,
If this is a jammer then y it's effect is only seen on other sectors when sector Z is ON?