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Valued Contributor
Posts: 896
Registered: ‎07-17-2009

Uplink interference from a cell carrier ? (2.4)

We've got a brand new site installed near sprint taking massive uplink interference. Looking at the spectrum analyser, its a little clearner than normal here, most of the noise is less than 90 db, with some decent spikes from wifi routers, but overall much less than other sites performing much better. I believe sprint is running near 2.4 band here and before i spend the money on filters, has anyone ran into this before ?

Our setup is on 2 wimax frames, 60" sector separation on each boom, stood off the tower 3' putting our sectors within a few feet directy above sprints sectors. They've got a different Ericsson array here i haven't seen before, looks like 8x8 mimo setup from thier boxes. Our target rx power is -60, everyone locked at neg 60 are holding mcs 2,3 and 9. We've got this same sector setup cololated on 14 different sits and no other issues.
Trusted Contributor
Posts: 1,101
Registered: ‎01-05-2014

Re: Uplink interference from a cell carrier ? (2.4)

If it's Sprint, they're most likely using 2.5ghz radios and blasting a lot of power. We've had serious interference issues with them on 2.4ghz. Adding heavy shielding and getting as much distance from them as possible, along with having all the sectors facing away from their gear (so our back is towards their face) helped somewhat. I've never tried filters. We eventually ended up deploying on 3.65/5ghz at this site due to these issues.

Moderator
Posts: 221
Registered: ‎10-03-2013

Re: Uplink interference from a cell carrier ? (2.4)

Chris,

E1K or E2K at this site?

 

Thanks

Sakid

 

Occasional Contributor
Posts: 14
Registered: ‎04-21-2016

Re: Uplink interference from a cell carrier ? (2.4)

Whelp... that explains THAT problem. 

 

Thanks.

Valued Contributor
Posts: 896
Registered: ‎07-17-2009

Re: Uplink interference from a cell carrier ? (2.4)

Its 1000s having the problem, 2.4 ghz hardware. All of the 5ghz gear is fine and those are 2000s

Ill add some filters and see if it clears it out.


Any specific recommended filters sakid ?

Thanks Eric!
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CWB
New Contributor
Posts: 2
Registered: ‎06-27-2017

Re: Uplink interference from a cell carrier ? (2.4)

I am sure Eric is right. Sprint is  going around renting all the EBS (Educational Broadband Services) 2.5Ghz frequencies that they can acquire. Sprint is then loading this band with LTE and says 2.5ghz will be the basis of their 5G network. I am sure what you are experiencing will only get worse for anyone co-locating with Sprint. Other big players are starting to jump on this 2.5ghz trend. We have decided to build our own towers (190' Rohn 25's) because of this and the big boys looking hard at 3.5ghz and 5ghz for their use as well. We would rather avoid a potential fight we can not win. 

 

Your symptoms sound like classic front end overload. Sprints high power 2.5ghz signal has desensed/defeaned your ePMP radios. This  is also why the noise floor "looks" so good. The radios can not "hear" well so even noise "looks" lower than its actual level.  I would imagine your SM's are also transmitting higher than they would have to normally transmit to reach -60dbm back at the AP under normal circumstances. With the overload, the front end is most likely not reproducing the received signal correctly and causing the SM's to reduce their MCS level. 

 

L-Com has some good 2.4ghz bandpass filters. They are per channel. The filters are listed for 802.11B&G but will work for N gear (ePMP) up to 20mhz wide. The draw back is these filters will eat up to half (3db) of your power. 

 

On a side note...This is my first post here. I have been lurking in the shadows for a long time while deciding what equipment to go with and while we got our system going. I would like to think you (Chis), Eric, Newkirk, Ninedd, several others and the entire Cambium staff. There has been a ton of good information shared from all of your knowledge and experience. 

Valued Contributor
Posts: 593
Registered: ‎01-03-2015

Re: Uplink interference from a cell carrier ? (2.4)


Sakid Ahmed wrote:

Chris,

E1K or E2K at this site?

 


Hey, does that imply that there is 2.4 Ghz ePMP2000 gear?   LOL.

Valued Contributor
Posts: 896
Registered: ‎07-17-2009

Re: Uplink interference from a cell carrier ? (2.4)

installing the L-Com cavity filters did the job nicely.  took a 3 db hit on up and downlink, but the spectrum is perfectly clean, got a solid mcs 11 on a -81 uplink for testing.  perfect!    before the filters, couldn't hold a link at -70. 

Trusted Contributor
Posts: 1,101
Registered: ‎01-05-2014

Re: Uplink interference from a cell carrier ? (2.4)


Chris_Bay wrote:

installing the L-Com cavity filters did the job nicely.  took a 3 db hit on up and downlink, but the spectrum is perfectly clean, got a solid mcs 11 on a -81 uplink for testing.  perfect!    before the filters, couldn't hold a link at -70. 


Sweet... do you have a part number for that item?

Valued Contributor
Posts: 896
Registered: ‎07-17-2009

Re: Uplink interference from a cell carrier ? (2.4)

[ Edited ]

Eric Ozrelic wrote:

Chris_Bay wrote:

installing the L-Com cavity filters did the job nicely.  took a 3 db hit on up and downlink, but the spectrum is perfectly clean, got a solid mcs 11 on a -81 uplink for testing.  perfect!    before the filters, couldn't hold a link at -70. 


Sweet... do you have a part number for that item?


http://www.l-com.com/bandpass-filter-rf-splitter-24-ghz-outdoor-8-pole-ultra-high-q-wifi-band-pass-f...

 

here's the link!   you'll need 2 filters per AP unfortunately.   used 2' lmr 400 jumpers to return to the sector antennas