[151793] in North American Network Operators' Group
Re: airFiber (text of the 8 minute video)
daemon@ATHENA.MIT.EDU (Greg Ihnen)
Fri Mar 30 19:36:51 2012
From: Greg Ihnen <os10rules@gmail.com>
In-Reply-To: <218AB54691EB49439829EFD136F473CF2774E187@exchange2k10.corp.power1.com>
Date: Fri, 30 Mar 2012 19:06:01 -0430
To: Dylan Bouterse <dylan@corp.power1.com>
Cc: "'nanog@nanog.org'" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mar 30, 2012, at 6:01 PM, Dylan Bouterse wrote:
> A couple of thoughts. First, it's not fair to compare 24GHz to 2.4 or =
even 5Gig range due to the wave length. You will get 2.4GHz bleed =
through walls, windows, etc. VERY close to a 5GHz transmitter you may =
get some bleed through walls but not reliably. 24GHz will not propagate =
through objects as it's millimeter wavelength. That coupled with the =
fact it is a directional PTP product, you will be able to get a good =
amount of density of 24GHz PTP links using the same frequency in a small =
area (downtown for instance).
The comparison isn't on wavelength, it's on the unlicensed-ness of it. =
Think CB vs Ham Radio. Where 2.4GHz and 5.8GHz are congested people have =
no where to go but up. You may not be alone up there. Guys already =
running 24GHz links might look at the sudden availability of cheap 24GHz =
gear in a different light.
Granted there's many things in AirFiber's favor regarding congestion =
being less of a problem. The short range and high directivity, high =
cost, etc, but remember this isn't the only 24GHz product out there. In =
the kind of places where one of these links might be needed, others =
might have the same need.
If you're thinking about the implications of possible =
congestion/interference when you're thinking about a link between the =
main office and the warehouse at a plant to give the guys in the =
warehouse internet that's not mission critical that's one thing. If it's =
key infrastructure for your ISP business then things start to look =
different. The licensed links start looking better regarding reliability =
down the road because you have a protected frequency. For ISPs out in =
farm country this is less of an issue, but in the more urban areas it is =
a concern. You start getting interference to your backhaul and you've =
got serious issues. You possibly have downgraded service or no service =
at many towers involving lots of customers.
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> Another point, the GPS on the airFiber will also allow for frequency =
reuse to a point. I would like to see smaller channel sizes though. I =
hear it will be a software upgrade down the road. I'm shocked the old =
Canopy guys didn't code that into the first release to be honest.
The GPS/reuse thing is for transmitters that are synced, that is =
transmitters belonging to the same system. Someone else's system won't =
be synced with yours and you won't see that benefit. So if you're =
thinking that's going to help between competitors it won't.
Greg
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> Dylan
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> -----Original Message-----
> From: Owen DeLong [mailto:owen@delong.com]=20
> Sent: Thursday, March 29, 2012 7:18 PM
> To: Oliver Garraux
> Cc: NANOG list
> Subject: Re: airFiber (text of the 8 minute video)
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> On Mar 29, 2012, at 12:33 PM, Oliver Garraux wrote:
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>>> Also keep in mind this is unlicensed gear (think unprotected =
airspace). Nothing stops everyone else in town from throwing one up and =
soon you're drowning in a high noise floor and it goes slow or doesn't =
work at all. Like what's happened to 2.4GHz and 5.8GHz in a lot of =
places. There's few urban or semi-urban places where you still can use =
those frequencies for backhaul. The reason why people pay the big bucks =
for licenses and gear for licensed frequencies is you're buying =
insurance it's going to work in the future.
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>>> Greg
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>> I was at Ubiquiti's conference. I don't disagree with what you're
>> saying. Ubiquiti's take on it seemed to be that 24 Ghz would likely
>> never be used to the extent that 2.4 / 5.8 is. They are seeing 24 =
Ghz
>> as only for backhaul - no connections to end users. I guess
>> point-to-multipoint connections aren't permitted by the FCC for 24
>> Ghz. AirFiber appears to be fairly highly directional. It needs to
>> be though, as each link uses 100 Mhz, and there's only 250 Mhz
>> available @ 24 Ghz.
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>> It also sounded like there was a decent possibility of supporting
>> licensed 21 / 25 Ghz spectrum with AirFiber in the future.
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>> Oliver
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> I don't think it's an FCC issue so much as 24Ghz has so much fade =
tendency with atmospheric moisture that an omnidirectional antenna is =
about as effective as a resistor coupled to ground (i.e. dummy load).
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> The only way you can get a signal to go any real distance at that =
frequency is to use a highly directional high-gain antenna at both ends.
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> Owen
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