Small office / Home office
Here's a Wi-Fi primer to help the uninitiated

By Rob Pegoraro
The Washington Post

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Doesn't sound too exciting, does it?

But Wi-Fi has done this basic job a little too well. It has made local-area networking cheap and (mostly) easy.

Few people would go to the trouble of connecting a computer to a stereo or giving away Internet access in a park if it meant littering Ethernet cable all over the place, but with Wi-Fi those scenarios are eminently possible.

In that sense, Wi-Fi is more Swiss Army knife than cordless phone. The downside of this? Wi-Fi can be pretty hard for the uninitiated to grasp.

So for those who haven't tried out wireless networking yet, here's what you need to know.

First, realize that a Wi-Fi network can't replace your existing Internet connection — it can only make it better by extending its reach beyond one outlet. You can take your laptop to the sofa for your Web browsing instead of being cabled to a desk.

You'll need two pieces of hardware to build a Wi-Fi network. One is an access point, a book-sized device that shares your Internet connection by broadcasting a signal to computers as far as 150 feet away, but more likely several dozen feet (taking into account the way walls and floors can weaken the signal). Most cost about $100.

The other is a receiver, a card or pod that plugs into a computer. Most new laptops include receivers already, but if you need to add one it normally should cost $30 to $70.

These gadgets come in two main flavors, called 802.11b and 802.11g in lieu of catchier names. The former is the oldest, best-established form of Wi-Fi; newer 802.11g gear can transfer data more quickly while still working with 802.11b hardware.

How much faster? 802.11b has an advertised speed of 11 megabits per second (Mbps), but the actual speed you get after subtracting for losses from overhead and interference is more like 2 to 4 Mbps.
 
802.11g's advertised speed is 54 Mbps — but for the same reasons, its real-world performance is closer to 20 Mbps. In networks that include b and g hardware, g slows down still more.

Most people buy Wi-Fi just to share an Internet connection, and for that purpose good old 802.11b is more than fast enough; most residential broadband connections max out at 1.5 Mbps. G's extra speed is useful only for sending lots of data between computers and the home network.

But even though 802.11g's speed may not yield any real benefit, you'll probably wind up buying it anyway. Older, slower b gear is getting hard to find while offering few savings compared with g devices, and — more important — almost all g hardware includes a much better security system.

Security matters in Wi-Fi because your access point will broadcast every bit of data you send and receive online to anybody who cares to listen. Without some authentication system, you also will be inviting every random stranger with a laptop to hop onto your signal and borrow your bandwidth.

Older Wi-Fi boxes include an encryption standard called WEP (Wired Equivalent Privacy) to prevent these things from happening, but WEP was soon discovered to be badly broken and easy to defeat in the field.

Wi-Fi developers came up with a better encryption system called WPA (Wi-Fi Protected Access), but this arrived too late to be added to many existing 802.11b devices.

Because Wi-Fi is a standard, not a brand, you don't need to buy all your hardware from one vendor. You can mix and match parts and they'll all — usually — work together.