hey all,
we've got a client that wants some crazy stuff, and i need either
suggestions or confirmation that this is impossible/too expensive.
client needs 45Mbps pushed over 20 miles... and he wants it wireless. the
kicker is that they don't want a T3 because it is "too expensive" and it
would take too long to get installed. it doesn't need to be constant, but he
wants to move of 2.5GB within 45 minutes. this is in the chicago area, if
that helps any. so, i don't know, satellite?
- toby
"Cerqua, Toby" wrote:
client needs 45Mbps pushed over 20 miles... and he wants it wireless. the
kicker is that they don't want a T3 because it is "too expensive" and it
would take too long to get installed. it doesn't need to be constant, but he
wants to move of 2.5GB within 45 minutes. this is in the chicago area, if
that helps any. so, i don't know, satellite?
Rent a U-Haul for about $39.95, put the tapes or disks in the back drive
20 miles. Even in rush hour on LSD you should make the 45 minute
deadline no problem. 2.5 GB is nothing, the client could get 2.5 TB or
more if they wanted that way. How's that for throughput? Latency kind
of sucks though. 
John
Motorcycle with a bag of CDRs would be a better fit for this application.
A kid with a bike would cost a lot less per month then any typical data
option.
i don't know, satellite?
Satellite (Starband, Direct TV) aren't a choice in this matter. The
StarBand Internet service is currently being provided over one of two
different satellites, depending on your location: Either the GE-4
satellite located at 101� west longitude (W.L.) or the Telstar 7
satellite located at 129� W.L.
Speeds will often reach 500 kbps with targeted peak time speeds in
excess of 150 kbps. StarBand's current upload speeds range between 40
and 60 kbps. Peak time is weekday evenings and they are down constantly.
Now I know GILAT has some sort of business SAT package, but I'm not sure
what it cost and what is involved with speeds. If you friend doesn�t
mind a 24,000 foot up and a 24,000 foot down latency then maybe he could
call GILAT.
client needs 45Mbps pushed over 20 miles... and he wants it
wireless. the kicker is that they don't want a T3 because it
is "too expensive" and it would take too long to get
installed. it doesn't need to be constant, but he wants to
move of 2.5GB within 45 minutes. this is in the Chicago area,
In this 20 miles does he have Line of Sight (LOS)? A wireless protocol,
Mag Grid antenna, and an .5-1.0 WATT amplifier could do the trick. But
he needs to watch his DB levels so if he does use the 1.0 WATT AMP he
doesn't go over the un-licensed FCC spectrum.
if you have line of sight you can look into microwave equipment. the
spectrum(18,23,38 ghz) is generally liscensed so there are regulatory
hurdles to jump through unless you're down in the 5725-5825mhz unliscensed
band...
These days this mostly makes sense if there's no physical infrastructure
in place.
take a look at:
for radio's for that sort of thing.
joelja
Have he taken a look at RFC 1149?
BTW, since I haven't posted in a while, I might as well get the most out of
this one -- kudos to the networking wizards who posted yesterday that didn't
know the difference between 192.0.0.0/16 and 192.0.0.0/8. I was especially
amused with the guy who thought it had something to do with RFC 1918.
--Adam
802.11a might do what you need. Not sure if it has been standardized
yet, but if not there are a number of proprietary implementations
in the same speed range. It promises 50Mbps with similar properties
to 802.11b.
20 miles is going to be a long throw, but not outside the range of
possibilities if you have line of site and good rooftop acesss. You
will need some big antennas though. A site in the middle making it
2 10 meg shots would be ideal.
You're not going to do a high bandwidth link 20 miles in ISM with a
permitted EIRP (I think 4watts).
That doesn't seem to stop a lot of people from putting a 20+db gain
antenna on a 1watt input for this stuff, but 50 watts EIRP isn't anywhere
near legal.
FCC Part 15.247 limits EIRP. You can't legally put out enough power in the
unlicenced bands.
I believe there are limitations on antenna gain and total EIRP in
those frequency bands which would make it difficult - if not impossible -
to get any kind of link budget over that distance. I could be wrong, but
that's my reading of 47 CFR Part 247(I think that's the correct citation).
David Leonard
ShaysNet
client needs 45Mbps pushed over 20 miles... and he wants it wireless. the
kicker is that they don't want a T3 because it is "too expensive" and it
would take too long to get installed. it doesn't need to be constant, but he
wants to move of 2.5GB within 45 minutes. this is in the chicago area, if
that helps any. so, i don't know, satellite?802.11a might do what you need. Not sure if it has been standardized
yet, but if not there are a number of proprietary implementations
in the same speed range. It promises 50Mbps with similar properties
to 802.11b.
i read somewhere 802.11a was going to be like 50ft distance. you'll need lots of wireless bridges.
-craig
Sure you can, you get more power with more directional antennas.
Here's a company that will sell you everything you need:
They can get 25 miles. Using a 36db Yagi you can build the same thing
yourself, as many have done. You do have to back off the transmitter
slightly to stay within FCC limits, but 20+ miles 802.11b is easily
done within FCC limits.
I cannot speak to 802.11a, as I know nothing about how it works,
or the frequences and power involved.
If you've got doubts about the distance, have a look at this network. The
long haul links use Tsunami equipment. There's all sorts of stats and
whatnot on the site as well, correlated with weather data, etc.
http://hpwren.ucsd.edu/topo.html
The main site is:
The long-haul links go up to 45mb/s, and while I can't quite find it, I
believe there may be a few 155mb/s links.
Charles
Directional antenns increase effective power output. FCC has limits not
only on transmitter power but also EIRP.
A 36dBi with 100mw input will yeald an EIRP of over 220 watts, well above
the limit of sanity and the law for EIRP of unlicenced equipment in the
ISM band.
You'd have to back off to less then 2mw to remain in the legal limits.
I just ran some quick numbers, and a unlicenced 20mile link like that
would be possible, but I wouldn't sell it.:
1.75mw -> 36dBi antenna -> freespace -> 36dBi antenna -> reciever + mis
losses, has an EIRP of about 3.9 watts (legal).
You'd have about 15db of link margin, and that's much too little for a
reliable link IMO.
That's why I suggested two 10 mile links. There are a large
number of people in the 10-14 mile range with reliable links, and
very few people pushing further.
That said, some guy in NZ got around 35 miles as I recall using
off the shelf parts. It no doubt exceeded FCC regs though, but
that's not an issue for him.
If wireless is too expensive or not possible due to the technology/laws,
you might think about renting dark fiber from a non-RBOC type
company. Also there is companies like Cogent who will sell you a 100Mb
connection for $1000/month.
In a large metropolitan area like Chicago, you should be able to pay much
less than the monthly cost of a T3.
YMMV.
If your client is looking for radio as a way to pay an up-front capital cost
and avoid the monthly recurring cost to and dependence on a LEC, there are
terrestial radio products that could do the job.
Satellite, of course, is tremendously more expensive than a leased line at
those speeds and does have the TCP windowing headache from latency, though
it can certainly be made to work.
As for 802.11a, the 5GHz unlicensed window it will use hasn't opened up yet
(AFAIK - may be outdated info), and there are no commercial products
available. Even if they were, the 5Gig spectrum doesn't travel as well as
2.4 at similar power, and last I heard they weren't expecting to bump up the
power limits. Even if they are, the effective rate probably won't be above
30Gbps. I don't know of any technologies that operate in ISM or other
unlicensed spectrum that would meet your requirements.
Several companies have been building terrestrial links like you would need
for years. Check out Harris: http://www.harris.com. The military loves them.
Last I checked, their products will do DS3 clear channel at >20 miles with
modest ground clearance; they're probably up to OC-3 by now. Being tailored
to the Military, as you can imagine, they're very robust, but expensive. You
also have some licensing hoops to jump through, but the vendor can help. All
in all, a couple hundred $k one time expense isn't bad.
- Jeb
We use satellite here and get it over 45Mb/s easy (although that is across
a lot of customers rather than between just 2 hosts). However considering
leased lines are cheaper in this part of the world than satellite I can't
imagine it's a cheap option in the central US.
By the time you add the price of the circuit to the uplink site, and the
rental of 45Mb/s worth of carrier ( just how cheap do you think
enough carrier space for 4-45 (choose your compression) TV channels to
everywhere in North America is? ) and other costs ( mosts local govts
don't just let you chuck up 4M sat dishes without a permit) I can't image
satellite is an option.
Look at some of the other options people have outlined here (especially
moving the information via truck/motorbike/helo) and go back to the client
and discuss what they really want to do.
I beg to differ, at my last employer we used BreezeCom 802.11b equipment for
links around 20-25 miles using 24 dbi grid mesh antennas, two antennas on each
end, approximately 150-200 feet in the air (usually on water towers, or grain
elevators, fun climbing when I wanted out of the office..) all within legal
limits. (The sheriff's dept claimed we were causing interference and had their RF
engineer come check out all of the equipment near theirs, calculated output power,
etc, it turned out to be something else)
Of course, this is 802.11b, 11mbit claimed, 6mbit real under perfect conditions,
I prefer the 5.2/5.8ghz band myself seeing how my cordless phone, X-10, and everyone
else is now marketing their merchandise in the 'totally unused 2.4ghz unlicensed band'
Matthew S. Hallacy