Does 2.4GHz makes sense?

Hello everyone,
I’m currently using only 5GHz for all my access points.

I see Cambium makes also 2.4GHz ePMP.
In some cases, for example NLOS situations, 2.4GHz would be better.

Does 2.4GHz sectors make sense?
I think it’s a very crowded spectrum due to all home AP and other 2.4GHz devices, but I read ePMP 2.4GHz sectors are dual slant polarized. Does it help?
Is anyone using 2.4 here? How does it perform in cities?

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It depends on the conditions in 2.4GHz where you intend to deploy your network. I think in a lot of areas the spectrum is so congested that 5GHz would be a better option, but you may find the opposite in some places as well. I think the best thing to do would be some spectrum analysis of the band in your area and see what the conditions are.

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we've found that the EPMP does perform better than any other wifi platform in noisy environments, but as Alex said the only way to know is to use a spectrum analyser and see.     if you can, use the AP and antenna you want to use.   tilt only far enough up to reach your target audience to help control noise, it won't stop noise, but it will help some.   establish a good minimum RSSI with your installers.   you will not get links at -75 in the city, but they hold fine out in the country. every environment is different, and with proper planning you'll get good results.      you may want to look into the 450 in the 3ghz band.   it may or may not be clean, but if it is, in the city you'll get amazing results and reasonable penetration.

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@giuseppe4 wrote:
Does 2.4GHz sectors make sense?

Hi.  Well, I can tell you this from our own experience.  We run a couple thousand non-Cambium 2.4Ghz radios on our towers. These older non-Cambium radios work OK(ish) in the country, but they essentially don't work at all in the City. I'm not too surprised by that - because after all, there are 100's of routers and phones and whatnot visible in 2.4Ghz in the city, right?  Interference has rendered 2.4Ghz equipment non-functional, right?


So - I had this older non-Cambium gear on my house, pointing to my non-Cambium sector about 4Km away - right across town. LOS is good, signals are -60 or so, but it is right across town and I hear dozens of routers from my site survey.  This older non-Cambium gear would struggle along at about 1 Mbit per second of real throughput, and it'd maybe be able to get up to 3 or 5 Mbit at 3 AM when there was a bit less interference, but it also might only get to 700kbit at 7 PM when everyone is using their routers.  SO - I thought that 2.4Ghz is pretty much dead (of course) in the city.

Enter the Cambium ePMP...   So, I think to myself, well, I have this Sector antenna already there, and I have the mount and the 22dBi grid already there - and they already have RPSMA connectors on them....    so, I replace the AP (just the radio, connected to the same sector antenna) and I replace my CPE (again, just the radio, connected to the same DualPol grid dish) and that's that.  Same cables, same mount, same antennas, same aiming - no changes except the radios....

...and if I set the QOS to unlimited, I can get 60-70 Mbit download and 20-30 Mbit upload now, in a 20Mhz channel (2452Mhz) 

>Downlink    67.588 Mbps

>Uplink          26.376 Mbps

I normally have my radio's QOS set to 20 Mbit down and 2 Mbit upload, and it hits that bang on all the time.

>Downlink   20.625 Mbps
>Uplink           2.073 Mbps
 
SO - I think that 5Ghz would probably still be a better choice in good LOS situations, but I'm very, very impressed with what ePMP is able to accomplish in noisy 2.4Ghz environments.  As far as I can see, it's not dead by any means!
 
And, I'd bet if Cambium released a LITE licensed AP version, there would be more 2.4Ghz AP's deployed. :)  If anyone agrees that they'd like to try 2.4Ghz on a LITE GPS AP - click here and vote!
http://community.cambiumnetworks.com/t5/Your-Ideas/2-4Ghz-ePMP-LITE-10-user-GPS-Synced-Access-Point/idi-p/51619
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Your experience means a lot, and your posts are always very helpful! :) Thank you!

Could you post a Spectrum Analyzer screenshot from both SM and AP, just to add some more details?

Are you using GPS Sync 75/25, right?

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We recently started deploying ePMP 2.4GHz on our network.

We have a client I was just checking on whose SM is registered with -75dBm downlink signal, usually running MCS10-MCS12.  eDetect indicates that it's also seeing two interfering devices at -73dBm and a third at -51dBm...  And in that situation, I have the customer provisioned for 10/2 service, and can link test 10-11mbps down with no trouble.

j

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Great! How much throughput without any limit? How much users?

For that example customer, if I unbottle their throughput I can link test 35/12.   We currently have a max load of 5-6 clients on a single 2.4 AP, we're really just getting started migrating clients from PMP320.

BTW, most of the time when I check the stats it's showing about 20dB SNR, which does NOT match up with the -54dB and -73dB interfering signals that eDetect shows.  Either those signals are intermittent, or something else strange is going on because running at -75dB and 20dB SNR should put the interfering signal level at -95dB, as I understand arithmetic...

j

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Did you try NLOS? 

We strictly use the 2.4 for NLOS. And nLOS. 5ghz for LOS. Remember that link obstructions are not made equal. Leaf trees are easier to shoot through than reds, hills pretty much don’t happen. Houses can be trouble. Ect. Lots of if and thens with NLOS conditions. Having link requirements other than rssi is usually key. For example our installers don’t use rssi as the chief indicators, we require 50% or more of the link traffic to be carried on mcs13, no more than 20% on 12 to qualify the link in the summer, and more demanding in the winter.


@giuseppe4 wrote:

Could you post a Spectrum Analyzer screenshot from both SM and AP, just to add some more details?


Well, currently - the way ePMP's Spectrum Analyzer works, it's a PITA to run.  We have to put the ePMP into SA mode, save, reboot, change the IP to access it (and in our case - change the IP address range) connect to it, do the SA - and then step back through all that nonsense to hopefully get it back configured the way it was before.  SO - in short, it's too complicated to be able to do that right now.  I'll have to schedule some time and do that for you later. :)

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Don't worry :)
I often save a screenshot of Spectrum Analyzer from both AP and SM when I can do it. Even if not so updated can be an helpful reference, so I thought you had one!

If you'll have some screenshot in the future, it would be great to understand how much interferences the ePMP is dealing with!

PS for Cambium: The SA mode is insane to use in a real-world installed environment. You should make it more usable like it's on all other vendors!

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Why do you guys have to change the IP/network when you run an SA? I ran one the other night and I didn't have to change the IP or network. The only time I've had to change IP's is when the unit was defaulted. I will admit it's a little annoying having to switch between AP and SA mode.

I'm pretty sure now that the ePMP team has fixed a bunch of issues under the hood, they're going to be working on UI enhancements like making the UI more responsive, bringing back the traffic graph, and re-working the SA.

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Well, when I select SA mode and go to save, it says it's going to change from 192.168.100.1 to 192.168.0.3

SA_Mode_Change.jpg

So, I'll give it a try and see what happens with v2.6.1 


@ninedd wrote:

Well, when I select SA mode and go to save, it says it's going to change from 192.168.100.1 to 192.168.0.3

So, I'll give it a try and see what happens with v2.6.1 


What firmware rev are you running? And is this a radio that was in AP mode, or SM mode? I just double checked an AP running 2.6, along with another AP running 2.6.1 and neither one of them give me that prompt or change IP address when set to SA mode.

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Those prompts I’m pretty sure only show up if the device is getting its address via dhcp. If it’s an AP it will still get its dhcp address (ours do) the sm however is going to drop to that IP for the wireless side, the lan side if it’s in Nat should remain reachable

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OK - my SM is running 2.6.1 firmware.  It does pop up that IP address warning, but after it rebooted, I was able to run the SA on the 192.168.100.1 IP that the SM is set to. As mentioned, the popup does say it's going to change the IP, but it didn't - so that's good I guess.  We still can't run the SA remotely (from the shop) on a client's system witout driving to their house, but at least this is better than having to reconfigure the computer to a new IP address and range.

In any event - I'm on 2452 Mhz, 20 Mhz wide and this is what the Spectrum Analyzer sees

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Wow! A lot of noise and you have such great results? 

Good work Cambium!

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Hi.  Yes, I'm blown away with the performance.  Our previous gear would struggle to even work during evening time when there was more usage in the neighborhood, and the air was more 'full' with competative traffic.

Don't get me wrong - I wouldn't normally recommend 2.4Ghz in the city like this. And, we can tell by the modulation rates and by the spread of the MCS % that these are having to adapt and work to get the job done. These shots are about 1.5KM, 4 KM and 7.5 KM and they are clear and we could (should) be doing 5Ghz here. I wanted to try 2.4Ghz here because this was bascially a ''worst case test'' in my mind. I knew that the other brand we had really struggled to perform due to the noise, so we relaced them on the exact same mounts and even used the same antennas in a couple cases, and the difference is night and day.

Here's what the radio links look like - and the Link Test results of the 3 Mbit / 500 Kbit customer...

and the results of the 20 Mbit / 2 Mbit clients...

10.2.4.16_LinkTest_List_Mar15_16_2.jpg

10.2.4.16_LinkTest_List_Mar15_16_3.jpg

So - I wouldn't say 2.4Ghz is dead by any means.  I wouldn't normally use it in clear situations, but in non- or near- situations, I'd say ePMP works remarkable well for the interference it's dealing with.

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I think your experience answers exactly to my questions!
Is the speed stable? Are you using GPS sync? 2.5 or 5ms?