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.

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.

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Chris,

E1K or E2K at this site?

Thanks

Sakid

Whelp... that explains THAT problem. 

Thanks.

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!

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. 

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@Sakid Ahmed wrote:

Chris,

E1K or E2K at this site?


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

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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. 

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@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?


@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-filters

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

@Chris_Bay wrote:

you'll need 2 filters per AP unfortunately.   used 2' lmr 400 jumpers to return to the sector

It's too bad Cambium doesn't build a 2.4Ghz ePMP2000 Access Point with built in filtering. They have said that the filter wouldn't be useful in 2.4Ghz, but they clearly are very very useful in high interference locations. 

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@ninedd wrote:
@Chris_Bay wrote:

you'll need 2 filters per AP unfortunately.   used 2' lmr 400 jumpers to return to the sector

It's too bad Cambium doesn't build a 2.4Ghz ePMP2000 Access Point with built in filtering. They have said that the filter wouldn't be useful in 2.4Ghz, but they clearly are very very useful in high interference locations. 


agreed.   those external filters are PIA, expensive and a total of 3db loss on the signals.    add in they are very frequency specific so once its on the radio, just changing the channel requires a tower climb to change the filter... only 22mhz of bandwidth to use with those filters.   

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Yes, the two things I'd like to see (partly even if just to demonstrate a commitment to the ePMP @ 2.4Ghz product line) would be to have a 2.4Ghz Access Point version with filtering like the ePMP2000 and like UBNT has, and to also even have a LITE version of 2.4Ghz AP's like all the Cambium 5Ghz AP's have. 

It's puzzling to me for them to have a LITE version at 5Ghz, but to be missing a LITE version of the same product at 2.4Ghz. There isn't even really anything to build - it's just a matter of programming/licensing. Having a LITE 10+1 license version would reduce the cost of deployment, and yet would really net out to the same for Cambium longer term anyway, since mostly everyone would have to get FULL licenses before too long.

I just bought 8 ePMP2000's and sectors @ 5Ghz, and I decided not to get 2.4Ghz for those towers at this time on those towers, just budget wise. Had there been LITE versions @ 2.4Ghz, I could have gone ahead without breaking the budget, and as those filled up with 10 clients each, I would have bought FULL licenses anyway down the road.

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@ninedd wrote:

@yes, the two things I'd like to see (partly even if just to demonstrate a commitment to the ePMP @ 2.4Ghz product line) would be to have a 2.4Ghz Access Point version with filtering like the ePMP2000 and like UBNT has, and to also even have a LITE version of 2.4Ghz AP's like all the Cambium 5Ghz AP's have. 

It's puzzling to me for them to have a LITE version at 5Ghz, but to be missing a LITE version of the same product at 2.4Ghz. There isn't even really anything to build - it's just a matter of programming/licensing. Having a LITE 10+1 license version would reduce the cost of deployment, and yet would really net out to the same for Cambium longer term anyway, since mostly everyone would have to get FULL licenses before too long.

@I just bought 8 ePMP2000's and sectors @ 5Ghz, and I decided not to get 2.4Ghz for those towers at this time on those towers, just budget wise. Had there been LITE versions @ 2.4Ghz, I could have gone ahead without breaking the budget, and as those filled up with 10 clients each, I would have bought FULL licenses anyway down the road.


and the newer GPS chip too!!!