802.11, Horizon Drop-Off And Range

tadghin writes: "Rob Flickenger at O'Reilly Network has written a neat little piece about the range of wireless networks and how high antennae need to be to reach the maximum promised range, given factors such as the earth's curvature and the fresnel zone." Not that most people have solid transmitter disks and clear lines of sight to a wireless reciever miles away, but the more the better when it comes to bypassing modems and expensive per-computer hookups.

Comments

Re:Assuming terrain is all flat.

[KoReE]

I am part owner of an ISP that does wireless service. 25 miles is not feasible from what we've seen. It is possible, but with the stuff we're using (2.4Ghz unlicensed), it's not going to happen. Even with most of the licensed stuff, you're only going to see around 15 miles. The most we've seen reliably from our 2.4 stuff is 10 miles, and this was with an 80 foot tower at the customer location. We also use 5.7/5.3 Ghz equipment for 8mbit point to point service. This is in the UNII band. We have gotten a max of 11.1 miles from this stuff. Could probably get 15 miles with 2-foot dishes.

Hills and things do improve the situation with the equipment that we use with our 2.4 network. The perfect situation is one where you have some sort of blockage just a little before the end of your range. This helps to prevent your transmitters from interfering with their counterparts in case they're transmitting just a bit farther than they should be able to. The best idea would be a cellular style delivery. No reason to go 25 miles with a link. Why not saturate a town or city with transmitters? Build the system (as we are beginning to build ours) where the customer only has to have a small, inexpensive 11db (or lower) flat-panel antenna on their house, without an expensive amplifier or huge LMR-1200 cable.

Wireless is in its infancy, and it's probably going to give us all cancer, but I like being able to take the telco out of the loop (no pun intended).

Corporate Bandwidth Providers

[journalistguy]

Companies should show the love they feel toward their customers by increasing the broadcast strength of their Wavelan signal. I for one am sick and tired of having to enter corporate parking lots in order to check my email, read /., etc.

Although most corporate Wavelan users are considerate enough to not use encryption or passwords to protect their networks, a few paranoid companies have begun to implement these revolting practices.

Don't they understand that networks want to be free?