airFiber (text of the 8 minute video)

Greg Ihnen os10rules at gmail.com
Fri Mar 30 18:36:01 CDT 2012


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.

> 
> 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

> 
> Dylan
> 
> -----Original Message-----
> From: Owen DeLong [mailto:owen at delong.com] 
> Sent: Thursday, March 29, 2012 7:18 PM
> To: Oliver Garraux
> Cc: NANOG list
> Subject: Re: airFiber (text of the 8 minute video)
> 
> 
> On Mar 29, 2012, at 12:33 PM, Oliver Garraux wrote:
> 
>>> 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.
>>> 
>>> Greg
>> 
>> 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.
>> 
>> It also sounded like there was a decent possibility of supporting
>> licensed 21 / 25 Ghz spectrum with AirFiber in the future.
>> 
>> Oliver
> 
> 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).
> 
> 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.
> 
> Owen
> 
> 
> 
> 




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