Accidental IT is a series of technical how-tos for people whose job descriptions don't necessarily include tech support but who often find themselves doing just that for their co-workers.

Once upon a time, someone in the office (maybe you?) came back from the computer store with a brand new box and a great idea. You plugged in the office's first 802.11 WiFi router, and everyone was delighted when a few lucky laptop users were able to carry their computers into the meeting room and stay online.

Like many technical innovations, WiFi connections are no longer optional. A growing portion of the office relies on WiFi for their full-time connection to the company's servers and the Internet. But with the increase in use, you've noticed an increase in the frequency and volume of grumbles when users find spots in the office where they can't connect, or worse, when they simply lose their connection while sitting at their desks. Equipment that was originally put in place for use by a single user just doesn't cut it when mission-critical tasks are performed on WiFi-connected PCs.

Intermittent Connections
Your installation probably consists of a single 802.11b or 802.11g access point (AP). When it was installed, location was based on convenience rather than research. So, it was plugged into an available Ethernet port and powered up. When it was configured for LAN access, we hope the security features were turned on, but that's a topic for another story altogether. For now, be sure that the SSID is something other than "Default" and that WPA security is turned on.

As your WiFi network changed from novelty to necessity, more users started to rely on the WiFi connection for their laptops, PDAs, and some desktop units. The lucky ones simply signed on and started working. The unlucky ones got weak signals, or no connection at all. And as the user population grew still more, even users who could normally work without a problem began to lose their connections.

These are all symptoms of an unplanned WiFi installation. But now it's time to plan, even if it's after the fact.

Surveying The Landscape
A site survey is a requirement for any large WiFi installation where coverage is critical, because the improper placement of access points can get expensive. The good news is that for the typical small office, you don't need any fancy gear, or even special software. What you're trying to accomplish is to discover those areas that don't get a signal, then try to position your access point to provide a signal to the "blind" spots.

Take the simple approach. Pick up your laptop and walk around with it. Most WiFi card drivers include a power meter or some other indicator that shows the strength of the radio signal it's receiving. Turn that on, and watch it as you move through your office. There are more sophisticated programs like NetStumbler that provide lots of detail. But all that really matters is whether you can get a decent connection.

Click for full screen.

While you're walking around, take a map of your office (a photocopy of the fire exit floor map will do) and mark the areas you visit with the relative strength of the connection at each point. Once you've made a basic map and identified the problem spots, look at the building to see if there are obvious signal-blocking structural components like stairwells or elevator shafts.

		Products Mentioned In This Story Linksys Wireless-G router: $70 Wireless-G Range Expander: $140 HGA7T High Gain Antenna Kit: $40 Proxim ORiNOCO AP-700: $310 ORiNOCO AP-4000: $450 Hawking Technology HAI6SIP Hi-Gain Antenna: $25 WiFi Signal Booster: $140 Belkin Corporation Wireless Pre-N Router: $140 Wireless Pre-N Notebook Network Card: $100 ParkerVision Wireless PC LAN Card: $80 Wireless 4-Port Router: $100

The WiFi (802.11b/g) radio signal is a line-of-sight signal, meaning it doesn't bounce off things like walls, ceilings, or even the atmosphere, as some radio signals do. But it can get through some opaque objects like walls, ceilings, and floors under certain conditions.

Those certain conditions depend on how electrically dense the barriers are. A typical drywall wall between offices isn't normally a problem, but conduit, plumbing, or steel studs can increase the density. Going through several of these walls can defeat the signal quickly.

Radio power is measured in decibels (db), and a typical WiFi access point will produce about 110db. You can make a rough estimate of the area you can cover with an access point by simply adding up the value of the obstacles between the access point and the computer. The average office wall will eat up about 30db, an average human soaks up 15db. If you add a reinforced stairwell or elevator shaft, you can see that your 110db doesn't last long.