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Cheap Long Distance Wireless Networking
enkidu writes: "Over at this article on macintouch there are some people who show how to extend Apple's airport range to 7km using legal signal boosting antennae. Connections at 50km+ are also mentioned. With enough base stations, you could even build your own private ricochet network in your neighborhood. " This should work with any WaveLAN cards ...
looks like a fun hack.
Transmitter power limits were created for a reason.
Hmmm... that link is forbidden for me.
Its because The Man doesn't want you to know about technology that can reduce stock values in his favorite portfolio. Apologies to the author, I made a little mirror on my slow link if you want to try it.
Whether one transmits at 1500 mW or 4000 mW is not really relevant. My point is that when there are enough people trying to do this
long-range stuff (even at 1500 mW), the bandwidth will eventually get clogged enough to cause chaos.
It turns out that this isn't a big deal. Most wireless cards today use direct sequencing similar to the CDMA telephones. So if you have interferrence, it will be ignored if you have network ids and different pseudo random number sequences.
Also, the high gain antenna needed to shoot a long distance are highly directional. The 24dBi antenna that I have on my roof has a spread of about 5degrees of useful power. Since it is so small, the area that I'm "polluting" is somewhat small. Also, since they are so highly directional your antenna would have to be both in the line of site between the two sites as well as looking at one end or the other. Since these conditions are so hard to hit, even in crowded areas the chances of interferrence is low. And when you are interferring, you just pick a different network ID and the radios automatically discard the extra traffic. 2mbps is a lot of bandwidth and there's likele plenty for everyone.
Umm, Richochet uses CELLs.. this setup would basically create massive problems for anyone else wanting to use the airport. 'tis better to get a larger frequency spectrum and break it up into a honey-comb like arrangement with land-lines and/or relay-frequencies. Read up on cell phone technology.. it's effectively what you'd need to do for a wireless MAN.
In answer to your first question the 2.4 gig stuff is actually ISM band stuff. The ISM band is a 22MHz band centered around 2.4GHz. And yes, 802.11 radios talk all throughout this band.
That original reg was written a long time ago primarily so that "microwave" devices (like your microwave oven) and similar medical equipment (scary thought) would have a free high-frequency range to interfere with legally. Put your wavelan on top of an operating microwave on high and you will see about a 50% reduction in bandwidth.
The redone spec allows this sort of use, or obviously there wouldn't be a bazillion companys selling ISM-band equipment today including cordless telephones and wireless lan equipment. See my other post (it's long and +5) for a layman's rundown of the law as it applies to wlan's and ISM stuff in general.
~GoRK
Well, read my other post where I clarified this It's here.
Anyway, you can't tramsmit 30dBm+45dBi on this setup legally. To use 45dBi EIRP you'd have to have only 22.5dBm power maximum. Plus, you'd probably never make the link since that much gain would affect the shape of your radiation pattern. It would extend directly from the directional antenna in the shape of what amounts to a very long thin, pencil.
Think silly putty. Both antennas have to be inside the blob to make the link. The amount of silly putty is the dBm and the dBi is how much you stretch it out. You should check out some propigation patterns at even 24dBi. They are pretty skinny necked little buggers. I can't even imagine aiming a 45dBi antenna. Sure if someone else put their radio in that line it would be useless but then again, that propigation path is very small.
Hope this helps but it's probably clear as mud
~GoRK
Actually, FHSS (Spread spectrum frequency hopping) hops to a different frequency after a set amount of time. In 802.11 frequency hopping occurs on 76 distince frequencies in the 22Mhz ISM band centered at 2.4GHz. The hops are psuedo random and the radios are very expensive to jam. Even when you turn on your microwave, you only interfere with one or two hopping frequencies, so you notice maybe a 5% reduction in bandwidth and a couple retransmits but nothing too bad.
And as for the government's being concerned nonsense they are very concerned and I've seen quite a number of people get busted on 2.4GHz stuff. I dont know where you get off saying that sharing this band with microwave ovens is difficult. Remember that this is a 22MHz band and your microwave oven transmits about 50 feet or so. It's radiation curve is also very steep so it only interferes with maybe 1/50th of the band. Plus, microwaves have a 50% duty cycle on high so even when it's on full-blast it only interferes half the time!
~GoRK
Direct line of site is going to reduce your signal only based on the equasions for free-space loss. And it's not just LOS, but 60% of your fresnel zone has to be free too otherwise you're going to take a hit.
Indoors, you have problems shooting through walls (drywall gives about 3dB loss... so does glass). Insulated walls and coated glass give about 6-8dB loss, etc. A row of trees outdoors gives about 3dBi of loss.
The major problem indoors is multipath propigation (where the signal bounces off of walls and stuff. I had to WLAN a room that had angled mirrors around lightbulbs on the ENTIRE ceiling. It took *FOUR* access points (one in each corner) to get rid of multipath problems (the didnt really want to change their mirrored ceiling!
~GoRK
The radios you have described at 2Mbps are Frequency-Hopping spread spectrum not direct sequence.
Frequency hoppping spread spectrum (FHSS) radios deal with interference very well but the 11Mb radios are not frequency hopping they are Direct sequence (DSSS) and if you get two conflicting DSSS systems on the same channel (of which there are only 3 non-overlapping you have total interference! The radios will share bandwidth if they're supposed to be on the same WLAN (Same ESSID) and the same brand but if they are different ESSID's, and especially if they're different brands, they are most likely going to cause each other TOTAL INTERFERENCE. I deal with this problem every day attempting to co-locate 11Mb DSSS equipment. It's a real headache. I'm just glad some IDIOT hasn't gone and started soldering on his airport in between some of my DSSS beams.
~GoRK
There are a few solutions for this. I can't find one right now, but most are PCI cards that have a PCMCIA slot for X Brands wireless PCMCIA card. Some are removable and usable in a laptop as well, some aren't. Just check the sites dropped in the comments here by others. From the pictures at 3Com's Airconnect page, it looks like 3Com will have one, but it's not out now.
The 1.1 update did more than just fix bugs. For example, I no longer have to type in my password every time I come home, since the AirPort 1.1 software interfaces with MacOS 9's keychain feature and automatically connects to an available network if it has the password for it.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
Anyone know if this absolutely requires direct line of site? Or can this be used within buildings and such as well?
The card has a port that allows you to plug an external antenna to it, all they did was take the AirPort housing off, it's just a PCMCIA card inside a pretty package. There's some cards that will sell you a dipole to plug into their card to increase the range. Stop making yourself look like a jackass.
I'm a loner Dottie, a Rebel.
It's not as simple as power output. The radiation pattern is equally important.
I know that a 100mW card can do links of over 10km, given the right antennae (NO additional amplifiers, just good yagis)
Antennae don't boost power output, they just focus that power.
As for interference, it means the units are supposed to use a non-deterministic hopping pattern, such that they don't overly interfere with each other. If frequencies are found to be bad, they are skipped. The idea is, the hopping sequence of various radios adjusts so they all get their fair share.
I'm positive you know what you are talking about.. but from my experience, it is not necessary nor illegal to switch out antennae so long as you stay within spec. Granted, joe average may not know how to do this, and he shouldn't, but you are perfectly within your rights to 'modify' gear so long as you stay within spec.
It is illegal to sell a device that is not certified. It is not completely illegal to use a device that is not certified.
And though I'm not sure it really is illegal, it is also true that the port you are referring to is a non-standard connector. Gender-reversed, or reverse thread, or some such thing, as required by FCC.
Rombuu wrote "..if you were a) motivated and b) technically inclined enough to do this, would you be using Apple hardware in the first place?"
... errr, yeah.
Well, conceivably, sure!
No one will deny that Apple has made some stinkers, but they also have a pretty good record (compared to most computer companies) at making well-crafted products.
And as the article emmett posted the other day pointed out, the Airport is really just some COTS parts stuck together handily, and at not a bad price for the convenience.
It's not my primary computer any more, but I do have a happily functioning SE/30 on my island of desks, and have always thought of it as one the coolest machines I've ever seen. What it does, it does very nicely.
And I've seen few PC cases as easy to work with as the G3 case, or the swing-out-side PowerMac case of a few years ago (I forget the model name). Not my aesthetics quite, but installing a new drive in a G3 is much nicer than taking apart / cutting fingers on most cases.
So
timothy
jrnl: http://tinyurl.com/c2l8yr / foes: http://tinyurl.com/ckjno5
Uhmmmm hate to bust your bubble, but this is really old news. Our ISp has been doing long haul wireless form a couple of years. Of course wehn *I post something to Slash it gets declined... sheesh..
It you want to learn about 802.11 wireless systems in use for networks and Internet access, please do read out FAQ
Wireless FAQ
d. can't find webgear cards anywhere online!
See http://shopper.cnet.com/shopping/search/results/1, 102 14,0-1257,00.html?tag=st%2Esh%2E1257%2Esbsr&qt=web gear&cn=&ca=1257. At least a few online stores--including a few such as TechStore, Inc. that claim realtime inventory--seem to have WebGear equipment in stock. Good luck.
"Be Happy or Die." -- AoN
we seem to have a lot of wireless networking posts here and it finally got to me; I have an athlon 850 sitting around (finally got to tell somebody!!) here in the midwest (stl) and ran into all these different problems:
a. it is not cheap
let me repeat, it is not cheap
there are two basic options for a hobby lan the WaveLan cards or the WebGear Airport cards. The base stations for the wavelan are $600+ and those for the webgear are $500+
b. HUGE tradeoffs all over the place.
wavelan is fast at 11Mbps, webgear only 2
wavelan cards are $180/ea, webgear gives you 2 for $199
you can use an airport instead of the wavelan access point, but that has configuration problems. You need a mac to configure stuff etc. I don't think I know anybody who uses a mac.
c. no local electronic stores carry them
even good ol' compusa stopped carrying the webgear cards. (i called)
If I am going to spend this kind of money, it will *have* to be an impulse buy at a store!!
d. can't find webgear cards anywhere online!
the only thing you really want to get is not in stock anywhere on the web!! Everybody posts about bargain buys (2/$99 etc) but where are they????
we could do all kinds of fun things with cheaper wireless lans, I live in a univ-student area and we could have all kinds of cool hacks if these things were cheaper...
this is when I wish most that we had a mercata style group for slashdotters...if apple can sell $99 wireless cards, why can't anybody else???
(posts with links get moderated up...
hmmm... lets throw in some links@!!)
get this!
I'd appreiciate a response by anyone who knows more about the topic, as if definitely would be a neat means of communication.
"AirPort 1.1 Update
If you purchased an AirPort product, you will want to upgrade your base station and card to AirPort version 1.1, which features improved user experience, new functionality such as active roaming, and a preview version of the software base station .
Clarification: Only 3 or 4 devices may transmit at once. That's what I should have said. Obviously, more devices are allowed to exist, as long as they're not all transmitting at the same time. 50 users on one base station browsing the web is probably fine. 50 users on one base station all trying to upload or download massive files is not okay.
--
The members of a small co-op called cwx.net have established very similar service in northern Colorado. Basically, trying to get DSL out of US-Worst is hopeless if you happen to live in a building younger than 10 years, and AT&T is in no hurry to get cable modem service out here.
We are using Aironet (now Cisco) 4800 series packet radios to serve 256Kb/s and 512Kbps service to Fort Collins and surrounding areas. The 4800 series radios are marketed as `indoor' wireless equipment, but they work very well over long distances when used with 36"x24" grid antennas. My own station is 4 miles from it's access point. There are points in service as much as 10 miles out.
We are fortunate to have a line of mountains a few miles to the West for mounting access points. The toughest requirement is the line-of-site path. Obstructions are mostly impassable.
Maw! Fire up the karma burner!
So, "Cheap Long Distance Wireless Networking" already exists. Damned, I am using it as I write this. :-)
There's one caveat though. The FCC/ETSI regulations. From what I know, in the US there's some power limit on the transmitter, and then you basically can use whatever high-gain antenna you like. In Europe, ETSI regulations regulate the total output of the system (the device + antenna gain), so you cannot do very long distance links with this technology, because the larger (=higher-gain) you have, the less power you are allowed to transmit through it..
If you live in ETSI countries, there's a possibility to have fairly cheap high-bandwidth (8 Mbps full-duplex) point to point links over big distances using devices in public 10.3 GHz band (as opposed to 2.4 GHz typically used by BreezeNet, WaveLan et al). This is a bit more expensive (say, $10000 for both points). Here the main manufacturers are CoproSys, Miracle or Alcoma.
I have tried to simplify things, experts please forgive me.
PS It's plain silly to use 2.4 GHz equipment through trees, as the author of the article mentions - leafs block the signal in this band a lot.
When the range of the network is so great, what is to stop anyone with an iBook from just walking by and hopping on to your network? I don't know much about the airport's wireless networking. Would anyone like to go into it with a bit more technicality?
Although you can obtain the equipment legaly is it legal to actually use it in this manner?
Encryption: I may not agree with what you say, but I will defend your right to encrypt it...
Hey ! So many people complaining about bandwidth congestion and the poor users who didn't get their stuff upgraded.
Have you not been seeing those "FCC approved" stickers for decades ?? Ever wondered what they are for ? Hello !!
I know that many people around here are against any law that limit what people can do/say, but the FCC regulations are usefull here. They limit what you can emit so that you do not disturb other nearby equipment. So, if the limit is too low, go complain to the FCC.
Arguing that Apple made the Tx/Rx use a lower power to solve the issue is simply not enough. The thing should have been designed so that many people in the same area can use it, considering that other people around are using the maximum permitted by the FCC.
Not only is it not very fat, it's astonishingly narrow. IEEE 802.11 devices have a tiny little chunk of the radio spectrum - IIRC, only enough for 3 or 4 802.11 devices to be operating in the same area at the same time. This would be next-to-useless for setting up a neighborhood network, and it would probably bug the hell out of anyone else trying to use an 802.11 device nearby, as you would be effectively jamming them.
So I know next to nothing about the technicalities of spectrum usage (as my previous post to this thread apparently demonstrated :-). But, I do work in a large building that has several dozen base stations and many hundreds of wireless machines operating all the time. There are at least 5 basestations that I know of, operating within 20 yards of my office right now. There doesn't seem to be any significant congestion problems. Perhaps the hardware or software is doing some arbitration?
As I said, I'm not up on the technicailites involved, but in practice this seems to be much less of a problem than your post would suggest.
Sailing over the event horizon
Here is a Wireless HOWTO that covers just about everything including what and where to get wireless cards, antennas, cables, design, construction, amplifiers, etc. Look on the links page for all kinds of goodies wireless.
So, the "hack" here is that they drilled a hole in the side of their AirPort to enable them to plug the vendor-approved signal amp into the stock wireless card inside?
Yes, this will work with any WaveLan card. Of course it will, it's a Lucent product that's marketed for this purpose.
Call me back when you're homebrewing your own signal amps out of arrays of power transistors.
This is just like television, only you can see much further.
Actually, the Apple AirPort ***BASE STATION*** is a repackaged Lucent WaveLAN Silver. The $99 AirPort CARDS are so cheap because they're actually missing hardware. The reason those $99 cards require an iBook or certain models of Powerbook is because those models contain the rest of the hardware necessary for the AirPort card to be functional.
Let me be clear: The AirPort CARD that Apple sells at an MSRP of $99 IS NOT A FUNCTIONING Lucent WaveLAN card!
.@.
Short answer: Yes.
Longer answer: I don't see why everyone assumes that simply because someone's using Apple hardware, they're not technically capable. Lord knows there are lots of clueless people on both sides of the fence, but there are also lots of intelligent hacker types who just like the way Apple's stuff works. The cases are great for the upgrede-inclined, everything works the first time, every time, and we can run Linux or Virtual PC if there's something we absolutely have to do in another operating system. And that's just the Mac users. Just because you're using an AirPort base doesn't necessarily mean that you use a Mac - AirPort is the cheapest 11 Mbps wireless networking doohickey out there. And it works with all the wireless cards that conform to the spec (which is most of them).
Slashdotters in general don't seem to get the idea that sometimes, once in a while, the best solution to a problem might come from somewhere other than Linus, AMD, or John Carmack. Sometimes Apple hardware is just the best and cheapest way to get a job done.
Or did I just get trolled?
--
Not only is it not very fat, it's astonishingly narrow. IEEE 802.11 devices have a tiny little chunk of the radio spectrum - IIRC, only enough for 3 or 4 802.11 devices to be operating in the same area at the same time. This would be next-to-useless for setting up a neighborhood network, and it would probably bug the hell out of anyone else trying to use an 802.11 device nearby, as you would be effectively jamming them.
--
I admit I don't know much about the inner workings about the AirPort, but I do know that it uses radio, and I know that there's a finite amount of radio bandwidth out there. I'm guessing here, but I imagine that the chunk of bandwidth reserved for the AirPort can't be very fat.
If everyone started extending the AirPort's range beyond what is allowed (the article quotes 4000 mW), then wouldn't the available bandwidth get congested really fast, causing collisions, and thus breaking connectivity?
Getting the AirPort to work at great ranges would be great at the very beginning, but everything would soon come crashing down. Those regulations and limits are there for a reason, you know.
begin 644
The AirPort and Apple arent the only systems that go wireless. There are others that support IEEE 802.11 DSSS standard.
Check out:
ZoomAir
BreezeNet
SkyLine
MaxTech
...among others.
Perhaps that could be done. I'd just like to point out that before people came along, whales communicated through relayed songs thousands and thousands of miles all over the Earth--and I'm sure they weren't just saying, "hi! hello! age check?" Of course, engine noise and hunting has completely destroyed any remnents of the original world-wide relay chat system.
[pink beam of light]
This is one step toward a fully distributed wireless IP but not the last.
Spread-spectrum wireless ought to take care of the congestion problem. If the power is low enough then the FCC has no business regulating it or requiring licenses--all they should do is certify that the equipment does not have too much noise.
Then each node ought to communicate with its closest neighbors, instead of to a central cell. This way each computer dedicates a bit of its bandwidth and disk to the network, similar to the way Freenet ought to operate, and analogous to the way homeowners are required in many areas to dedicate part of their land for a public sidewalk.
Internet traffic can then hop from node to node, routing around congestion and taking advantage of least-cost routes. Any landlines or satellites used ought to belong to the public and be free to use by all.
I don't know if this is communism or anarchy or libertarianism or just free market capitalism in the extreme, but it sounds to me like the future, and a very interesting one!
For more info on such a project, please see: http://wireless.oldcolo.com/biology/dave-bio.htm, and consult Dave Hughes, one of the real pioneers of computer-based communication.
I'm not opposed to the Macintosh experiments. But we ought to spend some time thinking about how we can take advantage of some of the new technologies such as what Hughes is using, in order to expand our Freedom and use the Internet in a way that maximizes democracy and personal power, at a time when media giants are trying to take it over and make it safe for e-commerce.
Without actual access to the modified equipment, we cannot be sure that it meets the general requirements of 18 CFR 18.305 (or section 3 generally)
For 2.4GHz ISM transmitters, used by consumers, under 500W, the transmitter field strength can be no greater that 25 mV/m at 300 m. Replacing a 9tested) nondirectional antenna with directional could cause this limit to be exceeded in some directions
but how can they (or other LANs) use the ISM band? It was my understanding that ISM was intended for quite different use, and that telecommunications was specifically excluded. Isn't a network 'telecommunications"?
I've heard the 2450 MHz mentioned as a LAN freq. before. Is it possible Apple was just being lazy in referring to it as by the general name ISM, when there's a specific authorization for this use elsewhere in the law. Or is everyone just relying on the fact that ISM is relatively unregulated?
Authority: 47 U.S.C. 4, 301, 302, 303, 304, 307.
Source: 50 FR 36067, Sept. 5, 1985, unless otherwise noted.
Sec. 18.107
(a) Radio frequency (RF) energy...
(b) Harmful interference...
(c) Industrial, scientific, and medical (ISM) equipment. Equipment or appliances designed to generate and use locally RF energy for industrial, scientific, medical, domestic or similar purposes, excluding applications in the field of telecommunication. Typical ISM applications are the production of physical, biological, or chemical effects such as heating, ionization of gases, mechanical vibrations, hair removal and acceleration of charged particles.
(d) Industrial heating equipment...
(e) Medical diathermy equipment...
(f) Ultrasonic equipment... for industrial,
scientific, medical or other noncommunication purposes.
(g) Consumer ISM equipment... Examples are domestic microwave ovens, jewelry cleaners for home use, ultrasonic humidifiers.
(h) ISM frequency....
(i) Marketing... covers leasing, sale, etc
(j) Magnetic resonance equipment...
Does someone know the law on this? Because if it's a matter of squatter's rights, the FCC states that even if they certify the equipment, they can yank the equipment off an ISM band, if they decide it isn't a ISM use.
Sec. 18.111 General operating conditions.
(a) Persons operating ISM equipment shall not be deemed to have any vested or recognizable right to the continued use of any given frequency, by virtue of any prior equipment authorization and/or
compliance with the applicable rules.
__________
If you can go to bed, knowing you did a valuable thing today, you're very lucky. If you can't... it's not bedtime
Here is a list of other interesting wireless links
found at FreakTech
Plasma antennas are radiofrequency antennas that employ plasma as the guiding medium for electromagnetic radiation.
DIRC is a self learning, intelligent, and self organising network of small transmitting and receiving stations.
Impulse Radio a whole new wireless medium.
AIRNET Adaptive Interferometric Radio Network Enhancement Technology.
What's more, the Lucent cards have an external antenna jack on the side of the card. Saves you a little work.
Before ripping a product apart with a dremel tool, check to see that you aren't re-inventing the wheel.
- Some Id10t
(Note: There are no x's in my email address.)