-> 22.0.2 LTE/5G timing, what changed?

We’ve been running with this frame config network wide for a few years now: 15 miles, 80%, 4 control slots, 5ms, LTE co-lo frame 2. And we’ve been hanging back on and since it has been very stable.

There have been some cellco C-band rollouts around me this year and it has had a pretty negative impact on our CBRS gear. I upgraded my home sector to 22.0.2 last night and not a single SM would register. The upgrade did not adjust any timing or co-lo settings. It defaulted the LTE S frame to 7 like I would expect. Otherwise everything else was the same. I tried going to 5G-NR co-lo mode. Changed control slots a little bit to tighten it up according to the co-lo planning tool. Nothing seemed to work. Rolled the AP back to It came up with LTE co-lo disabled. I fixed that and things were back to “normal” after reboot. Obviously I don’t know exactly what the timing config is on these adjacent C-band systems. But my question is, with the exact same config, why does it work on and not 22.0.2? What changed in the co-lo modes? Seems the timing is not the same. Uplink is clearly getting clobbered.

Both the LTE and 5G-NR co-lo calculators shows this frame config is OK. If the C-band stuff is running 2.5ms, I would expect the same results on So I’m a bit lost here.

Also, my sector is an old school original 3GHz 450 AP. I’m almost wondering if the front end is getting overloaded. There’s a Verizon site about a 1/4 mile away which they look to be running 3700-3760 at.
Here’s a SA screenshot. Yes this is at 20MHz, but it pretty much looks the same at 5MHz. Swapping to a 450i AP may help, but that would be a lot of work for what I would expect to be minimal improvement with co-channel interference.

SA from my SM shows what I assume is the Vz 3700 system a bit more clearly.

I have the AP freq at 3560@20MHz. That’s the only channel that works currently. I was hoping to run R22 on the AP to get the faster SA since it can switch to 5MHz on the fly for the scan vs having to play the reboot game.

If anyone has any tips, I would greatly appreciate it.

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Seriously, crickets? Not even someone from Cambium? George, did you figure this out?

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@Ken_Hohhof No. Honestly, I haven’t had time to dig into it more. Are you seeing similar C-band issues up in your area?

Maybe @CambiumMatt can take a look here?

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To be honest I came across your post while looking for the colocation guide and LTE and 5G-NR colocation tools, which I did finally find.

We’re definitely seeing C-band on SA, can’t say if that’s the cause of our interference problems since the spectrum in 3550-3700 looks pretty ugly as well. APs see the most interference and upstream is getting clobbered except on the shortest links.

You guys have some PALs, is that not helping? Or not enough spectrum if you only use your PALs?

I think there were some changes detailed in the 22.0 release notes, sounds like they might explain what you ran into?

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Hi George,

I’m sorry to hear you are having co-location issues with 22.0.2.
Could you please help us debug the issue by providing engineering.cgi from the AP, before and after upgrading from to 22.0.2. You can email me the engineering files to balaji.grandhi@cambiumnetworks.com. Thanks!

What came of this? Like Ken, I arrived here looking for the guide too

If you’re looking for a good write up/guide on how to use the LTE coexistence tools, check out this post: