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1KM 802.11b @ 2MB
OffTheRack writes "Check out this web site to see how a guy in Egypt built his own line-of-site (H:Get? It's Punny.) 1KM broadband connection. Plenty of nice pictures." Pretty cool set-up.
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1KM, 2Mbps, 802.11b wireless link using
Linksys WAP11 + Yagi, in Hurghada, EGYPT
By: Hassan Adly
Hurghada, Red Sea, EGYPT
Posted December 10, 2001
Background:
I have an Internet cafe in Hurghada, Red Sea, Egypt, with an expensive broadband satellite connection, located 1 km from my house. The roofs of both buildings have a clear line of sight between them. At home I was previously limited to a V.90 modem connection, and remote administration of the cyber cafe network was impossible.
A fast connection between my house and the cafe was becoming more and more necessary, mostly in order to provide remote administration at acceptable speeds, but also of course to finally get fast Internet at home! Me-wann' download quicky-quicky now!
The Project:
A lot of aimless browsing brought me to I, Cringly. This man is a genius. On his "Pulpit" section is a treasure trove of articles on what I would call survival techniques in the digital age. After considering rolling my own DSL on an analog leased line, which would entail for me a hefty annual telecom fee (plus the rather high cost of Pair-Gain SDSL modems), I stumbled across This article about 802.11, which describes how Bob Cringley, with little trouble (use of telescopes notwithstanding), connected his rural home to a DSL connection he had set up 10 miles (16km) away.
So according to the theories gleaned from Cringley's article, I realised I could connect my domestic LAN to my workplace LAN, with the help of two wireless LAN bridging devices, and a couple of good antennae (and no annual fee!). Obviously worth further investigation..
I started with Cringley's 802.11 links, which sent me well on my way to wireless Nirvana. Detailed instructions and antenna designs abound, along with some innovative ideas (mostly about saving money, which is good).
After some quick price-researching I found that the cheapest 802.11 unit available that suited my purposes was the Linksys WAP11, which has detachable antennae, LAN-bridging capability, 128bit WEP encryption, and best of all, at the time of writing only costs US$134.- on Amazon.com! This unit has the best value for money available for this type of device right now. I lost no time in ordering me a couple of these gems and having them delivered to a friend in California who just happened to be on his way to Egypt a few weeks later. Lucky me!
The WAP11 has an out-of-the-box claimed maximum range of about 450 meters under ideal conditions, which even if true falls well short of my 1km requirement. I Also want to be able to connect at high speeds. A replacement is required for the antennae (obviously). So, logitech wheel-mouse in hand, I set about building some!
My first project was based on the ingenious Pringles can design. The hardest part for me about emulating the design on Rob Flickenger's website was finding Pringles cans for sale in Egypt. Fortunately I found a supermarket that stocks them and was able to build a pair. If you want to try the Pringles design let me warn you: Under no circumstances should you eat more than a few Pringles at a time! After eating a canful I was positively sick, to the point that all antenna construction was halted for two days! Unfortunately after all my efforts the "Pringletenna" link refused to work, either through a design fault of my own, or noise, or whatever. Maybe it's the grease in the pringles..
After much hand-wringing, beard-ripping, hair-pulling, etc, I decided to construct a more "industrial standard" antenna, which I did without much ado (pictured right). Sporting a 3 full wavelengths collector (compared to the pringletenna's 1 wavelength), and weather-proof PVC piping as the outer shell, these antennae from the start looked as if they meant business, and indeed they did, because as soon as they were installed and properly aimed, they produced a 2Mbps signal at 1km distance. Hurrah! Me do download at home quicky-quicky now!
At one side of the connection the LAN switch is more than 40 meters away from the antenna, with the other side about 20 meters. Instead of trying to push the WAP11's FCC-impaired signal through long antenna cables I decided to put my WAP11's right next to the antennae. Since the WAP11's aren't weatherproof I had to use a weatherproof housing.
I found these boxes (pictured above and left) at about US$10.- a piece at a local electrical parts store. To the left you can see how my access point as well as its DC adapter fit inside the box, with the LAN, power, and antenna cables entering through the side. BTW the DC adapter included with the WAP11 works internationally, supporting voltages from 110-250VAC. Very thoughtful on Linksys' part.
The roofs of both buildings are relatively secure, so theft of the AP is unlikely, however I am concerned about the fallibility of my housings, at the time of writing it is winter here, with average temperatures around 20-25C during the day, however in summer temperatures here in the Sahara desert can reach 50C. Additionally we very ocassionally experience high wind speeds (over 100km/h) and sand storms. The housings are rain and wind-proof, but whether the AP's will survive the extreme summer environment and sand storms is still a question unanswered. In theory I could install some forced-air cooling such as computer power-supply fans, but I've decided to let next summer be my creation's token reliability test (perhaps Linksys could pay me and use it in an ad-campaign like: "tested in the Sahara desert"..).
The WAP11's antenna connectors, I found to my chagrin, are unlike anything available in northern Africa. The "pigtail" connectors I have read about on American sites are unavailable in Egypt and considering that they cost about $60 each anyway, all the better. After days of driving from one electronics shop to another with no success, I decided to dismantle the standard WAP11 antenna and modify its connector for my purposes. After a lot of clamping, hammering and grinding, this is what I ended up with, a brutalized Linksys connector with a standard satellite dish N-connector jammed onto its backside. So instead of a $60 pigtail, I got a solution that cost me about $1 for the n-connectors (including the ones I destroyed during experimentation). I got the approximately 4 meters of cable I needed for free from a sat-dish repairman I know.
So far the most expensive modification was the 60 meters of Cat5 cable I had to pull from my LAN switches to the AP's.
For now I've set up one WAP11 as an AP, and the other as an AP client. I am using 64-bit shared-key WEP encryption (the WAP11 supports 128-bit WEP but higher encryption reduces speed). To support bridging mode and 64/128 bit WEP the WAP11 requires a firmware upgrade.
I should note here that the WAP11 has a nasty habit of going to sleep (for lack of a better expression) when there has been no traffic for a while. I solved this by setting my proxy server to continuously ping the client WAP11 from the other side of the link. That keeps them lazy WAP11's awake! I think Linksys should include a "keep alive" function in the next WAP11 firmware update, because this issue appears to be confusing a lot of people.
In order to preclude any unauthorized wireless access to my network I am planning to implement a Linux router behind the AP with CBQ routing to experiment with bandwidth management and deny bandwidth to unauthorized IP addresses. Not that we have many wardrivers in Egypt, but you can never be too safe, especially in Africa, eh?
My Costs:
2x WAP11:
$298.- (now $268 incl. shipping!)
60 meters CAT 5 cable:
$30.-
Yagi antenna parts:
About $10.-
2x Weather-proof boxes
$20.-
60 meters Electrical cable
$10.-
So for a total cost of about US$360.- I built a 1 km wireless link, running for the past 2 months at 2Mbps. Yay!
Future mods:
I am beginning to suspect that my choice of coca-cola cans as reflectors on the Yagi antennae may be affecting signal quality (hence the maximum speed of only 2Mbps). Hence I am looking for a flat-based can that has the same diameter as the coca-cola can.
Another modification I want to try is putting an Omni-directional antenna on the AP side. I'm combing newsgroups and websites for designs and ideas as time allows. My Dad has a nifty Senao wireless phone with a 60km range, and I'm trying to convince him to lend me his station antenna
For really long range links and highly improved signal strength, I believe one would require a bi-directional 2.4GHz amplifier like one of these hard to get wonders. Dear Santa, I want a couple of those military-spec 10 Watt amplifiers for Christmas!
Last on my wishlist is a UPS connected to each WAP11. I find that after power-outages the AP's take a while to see each other.
Noise issues:
Although I live in a small-ish town with presumably little electromagnetic interference, it is worth mentioning that this high-gain, 3 meter tall GSM network monstrosity is located about 7 meters away from my AP antenna, on the same roof. I really can't tell whether or not it is affecting my antenna. Across the road are a pair of of GSM omni-directional antenna towers (pictured below) which to my knowledge also don't seem to affect my link.
By: Hassan Adly
Acaila
Growing Old is Inevitable; Growing Up is Optional.
I have to second this comment.
I did something similar to this about a year ago with two linksys wap11's and external omni antennas. This is nothing new or exciting. After all I recall reading some something along the lines of a 75mile link with 802.11b equipment done in Spain. Now that's something interesting. 2mb/s over 1km in a flat, dry and treeless area is pretty lame.
Sorry. Missed my link. Type too fast:
You can check out the various power limitations for 802.11b across the world at this site:
Maximum Power Levels and Antenna Gains
A country to regulation listing is here
not to nitpick, but is it 100mw or 1 watt....100 mw = 0.1 w
So phreak03 claims the site has been up for "several years".
The author of the site, claims on it, that it was posted in Dec'01. Not really what I'd consider "several years".
The Cringely article referenced in the piece was posted Feb 7,2002.
Odd, what?
"Politicians are interested in people. Not that this is always a virtue. Fleas are interested in dogs." P.J. O'Rourke
The plastic in your coax (or insulation on your twisted pair) has epsilon of more than 1, slowing signal down. Light is fastest in vacuum, in air it's just a notch slower, but when you start adding solid insulation, it can get you down quite a bit.
Paul B.
One must remember that despite many believing otherwise, the US has no jurisdiction outside of the US.
Hmmm, guess what, this will take you to their damn ugly website where I'm sure you can find out more! I can't be bothered to read up on the phones, but did notice that they have a range of 802.11b hardware for up to 25kms that this guy would love to have, why? well they have lightning protection (surge arrester) aswell as being watertight and weatherproof with POWER over Ethernet (never heard of it before myself). He'd also have got a standard N-type connector, 273K-323K temperature range (he could still go to high though, just). The only wierd thing (is it not) is that it has a 10 Base T connector for the local network, so your 11Mbs suddenly gets chopped to a theoretical 10 before you even try to get anything out of it.
Never underestimate the dark side of the Source
the clinton administration relaxed export restrictions on 128bit products some time ago.
2Mbps at 1km point p-t-p is not much - we do that at work all the time (I'm working for a wireless ISP).
Linksys WAP11 is one of the worst pieces of HW I have seen (I haven't even looked at the worse ones). You need a trained monkey to monitor it (no SNMP - try using Cricket or MRTG) and have to reboot it once a week. Even if you have the monkey, the box won't tell you anything - no signal strength, no retransmission counter, just the packet counters (at least in version 1.009).
If you intend to build such a link, use either decent FHSS devices (but those are quite expensive), or something like SparkLAN (sorry, no URL, try google) - a friend of mine is using those for 5km 8Mbps links (under ideal conditions, of course). These are about $200 in Slovakia, don't know about US (or Egypt).
It is also better to use high-gain (like 24dBi) antennas - have a look at Andrew. Do not use omnidirectional antennas.
Also try to keep the HF cables as short as possible (the guy could have made them some 2ft shorter) and water-proof your connectors - or your link will go down anytime the rain coes (and will not come up after some months due to rust)
Ahh, to have American FCC regulations.....
/ ps 430/products_configuration_guide_chapter09186a0080 0e0299.html#1013548
http://www.cisco.com/en/US/products/hw/wireless
Americas - 4W effective power (out of the antenna). You can stick a 13.5dB antenna on a full power 100mW access point, no problem
Europe - 0.1W effective power. You can stick a 0dB antenna on a 100mW access point, or 2.2dB on a 50mW AP.
China - 0.01W effective power. You can stick a 0dB antenna on a 5mW access point. Anything more powerful you cant.
I geuss that rules out legal long range (or even short-range) hops in the UK. Anyone got any more information?
CPC sell a 22dB antenna with a high-power 2.4GHz video sender too. very naughty.
128-bit encryption can be exported legally. Anything more than 128, still cannot. In addition, 128-bit encryption cannot be exported to US embargoed countries such as Iraq, but that's a little different.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
I noticed that he mounted the antenna using what appears to be conventional Tie Wraps (AKA Ty Wraps). This is a very bad idea as the UV in sunlight will quickly break down the plastic Tie Wraps, turning them extremely brittle and the antenna will come crashing down to the roof.
I sent him e-mail to warn him about this but wanted to warn other Slashdot readers. If you must use Tie Wraps outdoors, use UV-resistant Tie Wraps which are usually, but not always, black. But even then, I would not recommend them in a structural role. It's fine to use them to keep wires neatly bundled and routed, but don't use them in "mission-critical" applications where a Tie-Wrap failure would leave something non-functional.
Hello everyone,
Stop! I can't take all this attention!
Anyway I wanted to shamelessly use this opportunity to post some comments:
Since I wrote that article my network has improved significantly. I now use proper N-connectors and RG213 cable, and I've got some links at about 5km now. I now have ten nodes installed, including one AP with a 9dbi omni.
All my AP's survived the summer and winter with no problems, the oldest units have been up for more than a year now.
If anyone is wondering how well the WAP11 deals with heat, they would be interested to know that last summer we had 47degC temps, and besides the operational nodes staying up, I left a WAP11 in my car. When I got to it it was warped and melted - but it worked anyway!
I never expected this kind of attention, else I would have updated my article.
Thanks everyone for the comments and emails!
Regards, Hassan