Hawaii Wi-Fi

wyldchild37 writes "Through all the hype about 802.11b, I haven't seen too many real applications being talked about. Now that's starting to change. Here's a story on a guy who has set up a wireless network covering a good chunk of the Big Island of Hawaii. His network includes base stations wherever he can place them, along with an assortment of amplifiers, antennas, and other gear."

Comments

Aloha Net

[spotter]

This is somewhat interesting, as a lot of the research that went into what became ethernet was originally developed at the university of hawaii, as a wireless network, called Aloha http://www.nightflight.com/foldoc-bin/foldoc.cgi?A loha

Bob Metcalf (of xerox parc, later founding 3com) went on and basically took the protocol's and put them on a wire (instead of wireless), and this led to what we know of ethernet today.

what 802.11 adds to ethernet (that aloha didn't have) is the request to send/clear to send protocol which prevents the "hidden sender" problem from appearing. This problem is, wireless cards only have a certian range, card "a" might want to send data to card "b", and card "c" might want to send data to card "b", but "a" and "c" can't see each other, so their can be collisions which they will never know about because they can't see the collision. (unlike in ethernet, or in aloha, where all the hosts are assumed to be able to see each other)

How To Do It Yourself

[hyrdra]

What this guy has accomplished here would really be a no-brainer for most on Slashdot. The only thing I can see stopping one is the financial aspect -- an even that's not high. $1000 will create a 256 user, 5 mile 802.11b omnidirectional network or a 25 mile PtP. Myself and three others are setting up a public network in Athens, Ohio. You would be amazed at how many cities will allow you to co-locate antennas on public service towers and buildings when you bill the service as non-profit and for the community.

Here is a low-down of the basic equipment needed for a high-range, omnidirectional base station:

- 15 dB 80" Omnidirectional Antenna
- 1W AGC Amplifier
- Linksys WAP11 (or your favorite AP here)
- N to N male Connector (amplifier to antenna)
- BNC to N male Connector (AP to amplifier)

All of the above cost under $800, and when situated in an area with good radio horizon, you can expect 11 Mbps for at least a mile, and 2 Mbps up to 10 (in some cases). Please note that it's against FCC regulations to operate a 2.4 GHz link at 1W with a 15 dB antenna. I doubt anything would come of it since it's not a huge increase over the limit in this area of the spectrum, however for the paranoid you should use an automatic gain control amp that adjusts power automatically to keep you legal.

Other than that it just depends on how much money you have to invest in these base stations to provide wireless roaming. What we have found is that two stations located near enough each other that they overlap tends to increase the power somewhat and allow more users on the system.

This is really the future. Once enough cities grow their own public wireless networks and the technology gets up in the 100 Mbps range (802.11a is not applicable as the range is very limited) at the current distance and power, we can say goodbye to the telecommunications giants for most things.

What we use

[JoshuaDFranklin]

We've got a wireless network set up in two small towns here. We just hooked up a guy about 6mi. outside of town. It look a 40ft. antenna, but I digress.

We use antennas and amplifiers from Fleeman Anderson & Bird Corp.

We use antenna masts from Radio Shack.

We've found that the most reliable access points are Cisco Aironets, 340s or 350s. They can cost $1000-1500, though, so go with Linksys/SMC/Netgear if you're not that worried.

Also make sure you tie up cables on masts with something, like guy wire or metal cable ties, that doesn't disentigrate in a couple months. Always tape up the ends of the cables with electrical tape or use that rubbery stuff for protection from the weather.

And have fun!