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NissiAdonai

join:2012-08-23
united state

1 edit

Motorola/Cambium Networks PMP 320 in 2012

I have done some research, talked to a sales rep, and read some posts on this forum, but I haven't come up with any solid real-world information about the PMP 320 that isn't, what, two years old or more.

I would like some info from people who have actually deployed this. Questions that come to mind:

- Real-world range.
- Non-LOS performance when dealing with trees and hills.
- Maximum achieved throughput with ideal conditions AND in non-LOS long-range applications.

Currently we exclusively use Motorola/Cambium Networks PMP 100 as our customer-facing equipment--900 MHz and 5.7 GHz. Even PMP 100 5.7 GHz is great for LoS, but 900 MHz seems like a finger-in-the-dam situation. We are looking at the PMP 320 series so that we might:

- Overcome 900 MHz interference from other WISPs.
- Become more competitive and more consistent with our advertised and actual speeds.
- MAYBE expand into areas where we are traditionally trumped by DSL (in town).

We currently serve over 400 customers from 7 towers. I won't completely disregard suggestions for other equipment, either.


NissiAdonai

join:2012-08-23
united state

1 recommendation

I saw this post had a lot of views so I just wanted to give everyone an update. We bought an AP w/ 90-degree antenna and 3 SMs w/ integrated antennae (14.5 dBi, I think) and this is what we've seemed to find so far:

A bit different from other Motorola/Cambium Networks stuff, but I think we've partly figured out a good bit of it. What I say here may be simplifying things, but I don't claim to completely understand everything myself. I also may leave out a lot of the stuff that has already been explained in the advertisements/announcements/powerpoint presentations.

Before I go any further, I did see a post where someone was unable to achieve distances greater than 1 mile. We had this problem as well until we realized that our AP transmit power was set to -5. We bumped it to 20 and have been generally liking what we have been seeing.

Okay here we go. Maximum speed, both to a single SM AND total available at the AP, simply put, basically depends on two things:

1. The modulation level of each connected SM--and there are 9 of those.

2. The bandwidth of the channel you select.

We'll start with number one. If you are familiar with Canopy PMP 100 900 MHz, this is roughly similar to 1X or 2X, but seems more important to pay attention to here. With 900s you have, say, 3 Mb of total downlink throughput available, but ONLY if everyone is connected at 2X. With 1X, there is about 1.5 Mbps available. So try to follow this scenario with me. If you already know all this then you can probably skip this section. If you see a mistake then feel free to correct me. I haven't had any Motorola/Cambium training. In the beginning I was really only hired as a bottom-tier field tech, so I am meek and lowly of heart.

- 2 SMs (Isaac and Jacob) at 2X at a 1 Mbps tier.
- 1 SM (Esau) at 1X at a 1 Mbps tier.
- The 2 SMs at 2X start downloading at full speed. They are doing great because there is a full 1 Mbps left on the AP, right?
- The 1 SM starts downloading at full speed. Now, all three of the customers drop to below their subscribed speed.

Why? Because Esau is using more LINK BUDGET. See, the AP has to "work" just as hard to send 1.5 Mbps at 1X as it does to send 3 Mbps at 2X. Therefore, as far as Isaac and Jacob are concerned, Esau is actually using 2 Mbps worth of their link budget.

But the PMP 320s, on the other hand, have NINE modulation rates. What this means in practical terms is that a policy should likely be set in place dictating the lowest modulation rate an installer ought to accept. You, as the privileged owner who further has LoS to the tower, might have a 12 Mbps connection; but if you are connected at the highest modulation rate (called "qam64 ctc-5/6 MIMO B"; and btw, that is the ONLY modulation rate that connects at MIMO B) you might STILL be leaving plenty of link budget for the rest of the network even when downloading at full speed. If the practical maximum AP throughput in ideal conditions is, say, 40 Mbps, you are only using a little more than 1/4 of the link budget.

BUT, if you connect an SM at the lowest modulation rate (qpsk-ctc-1/2), then they would use the ENTIRE link budget at the AP to achieve just 2.6 Mbps.

So, depending on the modulation level, the link budget is affected to varying degrees. There are a few things to note:

- Only at the highest modulation level (where MIMO B becomes available) does the AP have significantly more throughput capability than a single SM.
- Some of the specific numbers I have mentioned here only apply when using the highest channel bandwidth: 10 MHz. Which leads us to item two...

Number two, the channel bandwidth, is a bit more straightforward. 10 MHz, 7 MHz, 5 MHz, and 3.5 MHz are your choices. This is set at the AP, so should probably be decided in the early stages of deployment. If you select 3.5 MHz for better connectivity, but later decide that you want the better throughput of the 10 MHz channel, some of your customers might drop entirely. Others might drop to a lower modulation rate, thereby slowing your network down.

Conversely, if you start at 10 MHz, but then decide that you want the greater range and/or connectivity of the 7 MHz channel (~10 miles vs ~6.9 miles), then it may not be an issue UNLESS you have quite a few customers connected at a high modulation rate. The switch to 7 MHz would then increase link budget usage at absolute speeds, especially for those connected at MIMO B.

Another thing I've found is that, while we generally install the 900s as high as we can, that is not always the best place for the PMP 320 SMs. I think this is because they employ something called "receive diversity." That is, if I understand correctly, they can actually benefit from signal reflections. So, for example, the reason one of our 7-mile non-LoS tests worked better at almost ground level instead of on the roof where the 900 is, was probably because the signal was allowed to reflect off the ground and the metal wall behind it, and possibly the metal roof above it. The signal stats even include two or three numbers for "CINR re-use." CINR = Carrier to Interference-plus-Noise Ratio. (The CINR stat seems more important with PMP 320s than the RSSI/power level is.

Anyway, I can't say this with certainty at the moment, but I THINK CINR re-use might have to do with this concept that I will copy and paste from the manual (the emphasis within the quote is my own):

In field deployments with a rich LOS multipath that can be converted to MRC gain, the dual-receiver architecture of the PMP 320 can achieve the same level of performance at greater distances since the RSSI and CINR levels at the radios can better by 3 dB or more than those listed in the table, which was measured in an environment with no multipath.
That's all for now. Our limited testing, both in town and out, LoS and non-LoS, including shooting through trees and past ridges, has been enough to cause the boss to give us the green light on getting four sectors set up on our main tower.


Jerm

join:2000-04-10
Richland, WA
kudos:2
reply to NissiAdonai

Great info for any other Moto users out there.

I remember a few years ago when Canopy was King...

Just curious though, would you suppose the improvement noticed on your "ground" test was simply due to less 900mhz interference at that location?

I wonder what kind of results UBNT 900mhz users are seeing, I remember a couple years ago when they were bragging:

"BREAKTHROUGH 900MHz PERFORMANCE
20Mbps+ Real TCP/IP Throughput in 5MHz Channel"

Yeah riiiiiight eh?


wirelessdog

join:2008-07-15
Queen Anne, MD
kudos:1
reply to NissiAdonai

Ubnt 900mhz is garbage



WHT

join:2010-03-26
Rosston, TX
kudos:5

I never got on board with UBNT 900, but lot of users haven't been all that thrilled with it.


Chele

join:2003-07-23
kudos:1
reply to NissiAdonai

I have no previous experience with any 900mHz. With that out of the way, we have a UBNT 900mHz POP. It has been extremely stable and we are getting more throughput than what we need. I can't remember the exact numbers but when we did the initial testing, we were getting around 25mbps. It is a Rocket with original subscribers. It has been so quiet that I got paranoid and ordered extra spare units--just in case! There is another WISP in that area and I think they also use 900.


LLigetfa

join:2006-05-15
Fort Frances, ON
kudos:1

Why all this talk about 900 MHz when the OP is about the Cambium Networks PMP 320 which is 3.65 GHz?



Inssomniak
The Glitch
Premium
join:2005-04-06
Cayuga, ON
kudos:2
reply to NissiAdonai

Yea I'm gonna have to say, following a few simple rules, that ubnt 900mhz works quite well for us. One of the simple rules being, don't use more than one at a site!

We are getting 12-13 megabits in 8mhz with good signals.

Back on topic! Lol
--
OptionsDSL Wireless Internet
»www.optionsdsl.ca


LLigetfa

join:2006-05-15
Fort Frances, ON
kudos:1

said by Inssomniak:

Back on topic! Lol

I'm surprised you can even find clear spectrum what with all the SCADA and smart meters, etc. using 900 MHz whereas 3.65 GHz is about limiting and managing spectrum use with hopefully a lower noise floor.

Of course there are the nLOS losses issues which are higher than 2.4 GHz.
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey

jcremin

join:2009-12-22
Siren, WI
kudos:2
reply to wirelessdog

said by wirelessdog:

Ubnt 900mhz is garbage

Ditto. Worked like crap for me compared to Mikrotik/XR9 for 900mhz.


IntraLink
Premium,MVM
join:2002-08-14
Uath Valley

1 recommendation

reply to NissiAdonai

We are using UBNT 3.65. One customer yesterday was getting 89Mbps from speedtest.net. Granted he was at full modulation at 1/2 mile from the sector on 25MHz channel.

But we are doing these out 7 miles at great modulation and some sites are pretty close to each other.

Lovin it!


gunther_01
Premium
join:2004-03-29
Saybrook, IL
reply to NissiAdonai

IDK how anyone is using 3.65 for PtMP with the rules in place. Unless you are breaking them.

You can't even turn on a 3.65 device without it being approved for it's location.

Maybe one of these days if they changed things a bit. But until then your just breaking the law and run your own risks for that. Plus make the industry look bad when there are problems because of it.
--
»www.wirelessdatanet.net



IntraLink
Premium,MVM
join:2002-08-14
Uath Valley

It's not that bad, our sites are all registered along with the client sites. They eventually show up on the FCC site map with everyone elses registrations. It's helped us map where we likely can use the 3.65 to success.

But if you find a provider not registering, then help them report their sites, and include the FCC if necessary.


gunther_01
Premium
join:2004-03-29
Saybrook, IL

said by IntraLink:

It's not that bad, our sites are all registered along with the client sites.

So your waiting weeks to get approved to turn on a client site? Last I knew, and heard that was about the time frame..

After the fact registration doesn't cut it. That's the major problem with PtMP using this band and the available equipment. It would be one thing if any of it was mobile certified and you didn't have to register, but most isn't (almost none)
--
»www.wirelessdatanet.net

NissiAdonai

join:2012-08-23
united state
reply to Jerm

said by Jerm:

I remember a few years ago when Canopy was King...

Should we be using something else? I've heard that Ubiquiti has lots of issues with supply. Try to order something and your distributor is out of stock, then have to wait months to install new subscribers--or repair existing ones! Sounds like a nightmare...

said by Jerm:

Just curious though, would you suppose the improvement noticed on your "ground" test was simply due to less 900mhz interference at that location?

The 900 was off at the time. I tested the 320 on the same bracket we were using for the 900, and I removed the 900 antenna first.


Inssomniak
The Glitch
Premium
join:2005-04-06
Cayuga, ON
kudos:2

Ubiquiti has has supply issues, but never had to go months without finding somewhere to get stuff.
--
OptionsDSL Wireless Internet
»www.optionsdsl.ca


NissiAdonai

join:2012-08-23
united state

Does it have GPS sync or some other way that we could minimize self-interference with our current Canopy deployments?



Inssomniak
The Glitch
Premium
join:2005-04-06
Cayuga, ON
kudos:2

the 2.4/5.8/3.65 stuff does, and it doesnt work well from reports, and you couldnt sync it with Canopy anyways.
--
OptionsDSL Wireless Internet
»www.optionsdsl.ca


LLigetfa

join:2006-05-15
Fort Frances, ON
kudos:1

said by Inssomniak:

...and you couldnt sync it with Canopy anyways.

Ja, that was my thought. I think if you already have Canopy in 3.65 that you would either stick with it or forklift it.
--
Strange as it seems, no amount of learning can cure stupidity, and formal education positively fortifies it. -- Stephen Vizinczey