I have heard a number of times that Canopies are ‘bad’ because they stomp
on other radios in the area taking them off line.
Since no GPS’d polling radio listens or holds off while other radio’s are talking, one would expect the
Canopy 100’s say to be opportunistic and try to get its signal through to its SM regardless
of what other area radios are doing.
I would expect all polling radios to behave the same way regardless of their make.
Is there some difference in the coding of the canopy signal that would cause it to be more destructive to other radios trying to talk in polling mode also? HOw about WiMax, is it destructive to non WiMax codings, or visa versa.
I am assuming a radom collection of AP’s and SM’s belonging to different providers, on the
same channel, perhaps Canopy’s, Alvarions, or whatever.
Thanks for your insight.
Homer
The Canopy system is centrally timed by the AP off of GPS. It is a fixed timing structure and there are never any dead spots, unlike 802.11. With Canopy the AP is always transmitting, even if there is no data for the frames. It’s also very high power with very low spectral efficiency - in the 2.4 GHz product an entire 20 MHz channel is used for only 14 Mbps! (“Advantage” radios). This makes it very destructive to WiFi-based equipment. Canopy will overpower anything else, and it will win as the FSK coding is so robust.
Not totally sure on the inner workings of WiMAX, it is a technology rooted in cellphone land. If you’re using a non-WiMAX equipment in 3.65 GHz range the FCC might like to have a chat with you!
OK, thanks. Let’s see if I got this.
We are talking abut 5200 and 5700 Canopy 100’s not the 2400 competing with 802.11b/g
However we might be talking about 5700’s competing with 802.11/a.
You have said that the Canopy FSK coding is robust so it works well.
Would the 5.7’s be ‘unfairly destructive’ to Alvarion or other high end radios using mac scheduling (polling) or Ubiquities using Airmax?
On the same channel? On separate channels? With some (5Mhz) overlap channels?
Is there any possible ethical or moral reason to consider Canopy’s bad due to excessive ‘damage’ to the radio spectrum used, relative to other competitive providers?
I had a comment from a provider using Alvarion and other radios that they refused to use Canopies because of destructive ‘unsocial’ behavior in the competitive world.
Even if true, I would think that as a competitive provider myself, I would WANT to use the system what would survive best regardless of what other’s used, unless the radios were egregiously or incompetently built to waste spectrum space for the bandwidth that they offered.
Homer
Essentially, Canopy only plays “well” with itself on the same frequencies. Whereas with some 802.11-based gear you can get away with a certain amount of channel overlap, the high power FSK will just drown out everything so you HAVE to use proper frequency planning.
This is generally the real source of complaints from operators regarding Canopy. The old story is that once upon a time, Provider A was operating with (low power high modulation product like Alvarion) and Provider B shows up with Canopy. Provider B has no requirement to actually coordinate a frequency plan with Provider A because the Canopy just drowns out everything else.
Properly planned to avoid interference it works fine. Canopy does very well as far as behaving as expected, it stays within the indicated band with predictable rolloff. We operate 2.4 GHz 802.11g and 2.4 GHz Canopy side-by-side with proper planning. There really isn’t anything magical or evil about it.
As a provider, the same aspect is a huge advantage in certain situations. If you’re uncooperative like Provider B in my above example, the benefits are clear. On a smaller scale, a more robust transmission is great in the unlicensed bands with every idiot on the planet with baby monitors, wireless routers, and video senders. Those devices only affect the customers’ individual SM instead of the whole neighborhood or an entire tower.
Like you mention bandwidth is a big issue… 14 Mbps on a 20 MHz 2.4 GHz chunk is pretty lame. The 900 MHz product is even worse - you get 3 channels capable of 4 Mbps each, max. If you want bandwidth, Canopy isn’t really the way to go. PMP450 promises a lot, but we’re into WiMAX for all of that.
Don’t mean to reply to my own posting…
Seems like what you are saying is that different encoding schemes can be destructive
to other encoding schemes.
For example FSK wins over 802.11b/g/a.
Can the same thing be said about relative destructiveness between other coding schemes
such as OFDM and others against FSK or 802.11?
Homer
It’s really a matter of power levels and interference tolerance in that regard. More specifically, a 1X Canopy FSK link only requires 3 dB SNR to function. 2X is enabled with only a 10 dB margin! If you have OFDM competing with OFDM at the same power level and on the same frequency, both devices will have a huge problem and problems will be apparent on both sides. Canopy just doesn’t care and will operate fine in that environment. In fact the PMP100 equipment doesn’t even HAVE an SNR display.
In WiMAX land you’ll see the modulation drop respective to the SNR. Cambium’s got a table of figures buried in the PMP320 system manual.
Thanks for the reply.
1.) Does every radio use a known modulation scheme, FSK, OFDM or similar.
2.) Many claim to be ‘proprietary’ schemes such as Alvarion, even Canopy, but isn’t
the underlying modulation always just one of many standard ones when it comes to comparing
performance and stomping power?
3.) If so, can there be any greater stomping power of one make over another given they are using the same power and underlying modulation scheme?
Sorry to be dense, I am trying to understand why one stomps on the other. If its just power out, well I would imagine every maker allows the max FCC limits in the unlicensed band, so the fact that Canopy’s put out so much power can’t be a reason to claim they are a problem as surely the Alvarions could be set to the same power.
Or is there something fundamentally different between Alvarions and Canopies.
that makes Canopies ‘unsocial’ or ‘not good for a society of friendly competitors.’
I tend to agree that if one is a provider one would want the most opportunistic stompers on the market, as long as they don’t waste bandwidth in doing so, as someone is going to eventually use them against you if your deployment is a pussy 
Homer
hwsmith wrote: 1.) Does every radio use a known modulation scheme, FSK, OFDM or similar.
Yes, there are really only a couple of methods for encoding in use today. OFDM being the most popular (it's what all the cool kids run - 802.11a, WiMAX, PMP 450; LTE 4G OFDMA and SC-FDMA)
hwsmith wrote: 2.) Many claim to be 'proprietary' schemes such as Alvarion, even Canopy, but isn't the underlying modulation always just one of many standard ones when it comes to comparing performance and stomping power?
Right. OFDM and QAM64, for example, are very common methods used extensively and all perform reasonably similar. What can make them incompatible is the implementation. A manufacturer might build in a few tweaks to change the performance or just break compatibility with third party equipment. An example I have of this is gear we run from a company called SkyPilot: It's a hack of the 5.8 GHz 802.11a with GPS timing and centrally controlled time-division duplexing. It's a pretty neat system that works well, but aside from the obvious differences between fixed multi access and 802.11 (WiFi doesn't deal with hidden nodes), it performs as one would expect 802.11a to. There are even Atheros mini-PCI cards in the CPEs!
hwsmith wrote: 3.) If so, can there be any greater stomping power of one make over another given they are using the same power and underlying modulation scheme?
Not really. What it will come down to is the tolerance of interference in a given implementation. A deployment with a very solid modulation and encoding hardware or software and good antennas will outperform a crappy RF software stack with omnis.
hwsmith wrote: Sorry to be dense, I am trying to understand why one stomps on the other. If its just power out, well I would imagine every maker allows the max FCC limits in the unlicensed band, so the fact that Canopy's put out so much power can't be a reason to claim they are a problem as surely the Alvarions could be set to the same power.
Or is there something fundamentally different between Alvarions and Canopies.
that makes Canopies 'unsocial' or 'not good for a society of friendly competitors.'
Haha no problem. It's important to understand things fully. What makes Canopy so special is that you can get "acceptable" links with only 3 dB SNR... of course it's crap slow, but it's stable, and no other gear will do that. Canopy operators would be a lot more cooperative if the gear made better use of the spectrum!
OK, what I get from this is that the problem is not CANOPY vs some other competitor, but
FSK over higher speed modulation schemes that provide more bandwidth/spectra, but which are more
fragile to interference/jitter/error and probably more expensive to deploy.
Thus when the goal is to get SOMETHING to the end customer in spectrall hostile territory, then using any FSK slower bandwidth modulation is justified but it will stomp over anyone else using higher speed modulations even at the same or higher power.
Homer
Yes that’s exactly it. It just so happens that Canopy is the only gear running FSK like that, and most other equipment (sometimes more expensive, sometimes cheaper… Alvarion and Ubiquiti will get destroyed the same) is trying to be more efficient.
With WiMAX equipment you might be able to get a similar behaviour by forcing everything to run in QPSK 1/2 on the largest possible channel, but then you have a very expensive, very slow AP.
I’d like to chime in and add that the original canopy platform is over a decade old… at its inception ofdm was in its infancy. (OFDM was actually invented by orthogon systems which over time, became part of the canopy family)
We use both canopy and ubnt gear both in 2.4 ghz without issue with PROPER planning.
FSK radios don’t detect and as salad said, doesn’t care that other information is present. The extremely low SNR requirements allow canopy radios to work in places other platforms won’t even establish a link.
a notable area, our canopy 2.4 radio will work fine down to -85 is some cases… -90 to -88 seems to be the 2.4 ghz floor in our area (generally speaking) a ubnt radio link at -80 will establish and might trickle a meg or two across the link. the canopy will fun full 14 mbps. in that situation, canopy is the perfect choice.
if you are able to get a -70db link, the tables have turned on speed and spectral efficiency.
as far as a 900 mhz product is conserved with all of the gadgets and gizmos out there running 900, in our area the ubnt would be worthless as we would need to keep everything -65 or better, at that power why even bother? canopy we can run 75 to 77 and it brings the 900 back into the mix. yes 4 mbps isn’t what it was a 10 years ago, but the gear is everywhere and cheep so why not get those customers?
as far as stomping… thats sounding a bit harsh, its not that cambium is out to break other radios, it uses a different mechanism. it uses fixed time slots and syncs towers together, 2 cambium providers would have no trouble running side by and running at 100% speed even if that speed is only 14 mbps. i want to point out with our UBNT gear, plenty of times have we seen good scores and everything looks great to simply see there is to much traffic on 2.4 and the radios constantly “pause” and they simply don’t perform. other times it is good. also if you want to note, the lack of GPS timing from UBNT and other wifi based products in my opinion make them not so efficient.
Here is why:
In this example lets say you have 3 towers, 3 miles apart, and they make a perfect triangle.
Lets also assume all radios are registered at -70 db which I think is a fair number, I’ll repeat my example again with -60 and -80 db powers.
Lets also set a static noise floor of -85 db for all examples.
With the cambium radios you will get 6x14 mbps per tower (84 mbps per tower, 252 mbps in the three towers)
Lets use ubnt as the other band since I am very familiar with the product line. One a single tower you cannot use 3x20mhz channels with the ubnt without causing some inference and already downing the efficiency from the get go at max TX power. But lets just assume you can.
So in this example, we have 3 towers with cambium gear, as deployed as cambium says to do deploy, we have 6 sectors, with 14 mbps per tower, that gives us 252 mbps available bandwidth.
At 70 db signal we have 15db SNR so the cambium is running full speed.
The UBNT deployment, deployed as UBNT says to deploy either 4x10mhz or 3x20 mhz (3x20 mhz will yield more speed in this example)
With a 15 SNR, you can get to MCS 12, 78 mbps. After overhead and everything is running absolutely perfect you get 45 mbps per sector. You end up with 135 mbps per tower, and 405 mbps per 3 tower setup. However here is the draw back from this setup. Say you need to add another tower? You are out of rf channels in 2.4, you need to use a different back, or reduce you channel sizes to make room. Dropping you channel size down to 10mhz with reduce your throughput 50% and now you have 202.5 mbps on those three towers. There are some smaller details I’ve skipped over, the outward facing APs can stay at 20 mhz channels, just the inward facing APS have to make room.
In this situation the ubnt has run out of radio room and the cambium them becomes the better choice. This situation would happen only in semi dense, or dense environments.
Repeating the above example at -80 db signal with 3 towers, the ubnt radios will not hold reliable connections so cambium becomes the choice again.
With -60 db average signal locks, the ubnt hardware can run full speed giving you 78mbps useable per sector, and over 200 mbps available per tower. So at great signals like -60, UBNT and other wifi base systems are the better choice.
Simply put, salad and I are both trying to point out that cambium radios function well at poor SNR, and poor signals were other platforms simply will not work.
Cambium doesn’t make a radio designed to “kill” other systems, many of the smaller wisps or low budget wisps HATE the canopy line simply because its so scalable and tolerant or problems and interference. I see why someone trying to start an wisp with only a few thousand would resent a line like canopy, we started with 150k 8 years ago and launched with canopy. Almost all of our original canopy gear is still up and working every day just fine, so being an operator for that long and have made my money back over and over again, mixed with an understanding of the product, I love it. With proper planning, it works well with other ODFM based hardware. Its time has come and has passed, and new systems are replacing it like the 450 from cambium, wimax E (we also run and love). Looking back at the life of the canopy 100 series radios, it’s a great product. Plays nicely only with its self, but it was made before wifi really even came into existence, so noting that, no it doesn’t place nice with 802.11 devices, it pre-dates them. Its like asking DSSS hardware to be nice and not kill an entire RF band, when most of those devices were made, the new 802.11 gear, canopy, alverion wimax ect. Ect. Gear wasn’t in existence.
And indeed planning is what it’s all about. I should mention that our Tranzeo 2.4 GHz 802.11g stuff shares a border with another ISP using 2.4 GHz Canopy. Works fine until they suddenly change frequencies
mgthump wrote: Its like asking DSSS hardware to be nice and not kill an entire RF band
LOL very true