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6. Move on to the next network (if any) that you want to configure.
Notice the Key Index scroll box near the bottom of the dialog box. By default, the key index is set to 1. Your office network administrator will know whether you need to use the key index. This feature is used if the system administrator has implemented a rotating key system, which is a security system used in some office settings. You won’t need to mess with this unless you’re setting up your computer to use at work — it’s not something that you’ll be using in your home wireless network.
7.After adding all the necessary wireless networks, click OK on the Wireless Networks tab of the Wireless Network Connection Properties dialog box.
Windows XP now has the information that it needs to automatically connect the computer to each wireless network whenever the wireless station comes into range.
Tracking Your Network’s Performance
After you have your network adapters and APs installed and up and running, you might think that you’ve reached the end of the game — wireless network Nirvana! And in some ways, you have, at least after you go through the steps in Chapter 9 and get your network and all its devices connected to the Internet. But part of the nature of wireless networks is the fact that they rely upon the transmission of radio waves throughout your home. And if you’ve
ever tried to tune in a station on your radio or TV but had a hard time getting a signal (who hasn’t had this problem — besides kids who’ve grown up on cable TV and Internet radio, we suppose), you probably realize that radio waves can run into interference or just plain peter out at longer distances.
Obviously, the transmitters used in Wi-Fi systems use very low power levels — at least compared with commercial radio and television transmitters — so the issues of interference and range that are inherent to any radio-based system are even more important for a wireless home network.
Luckily, the client software that comes with just about any wireless network adapter includes a tool that enables you to take a look at the performance of your network — usually in the form of a signal strength meter and perhaps a link test program. With most systems (and client software), you’ll be able to view this performance monitoring equipment in two places:
In your system tray: Most wireless network adapters will install a small signal strength meter in the Windows system tray (usually found on the bottom-right corner of your screen, although you might have moved it elsewhere on your screen). This signal strength meter will usually have a
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series of bars that light up in response to the strength of your wireless network’s radio signal. It’s different with each manufacturer, but most that we’ve seen light up the bars in green to indicate signal strength. The more bars that light up, the stronger your signal.
Within the client software itself: The client software that you installed along with your network adapter will usually have some more elaborate signal strength system that graphically (or using a numerical readout) displays several measures of the quality of your radio signal. This is often called a link test function, although different manufacturers call it different things. (Look in your manual or in the online help system to find this in your network adapter’s client software.) The link test usually measures several things:
•Signal strength: Also called signal level in some systems, this is a measure of the signal’s strength in dBm. The higher this number is, the better, and the more likely that you’ll be getting a full speed connection from your access point to your PC.
•Noise level: This is a measure of the interference that is affecting the wireless network in your home. Remember that electronics in your home (such as cordless phones and microwaves) can put out their own radio waves that interfere with the radio waves used by your home network. Noise level is also measured in dBm, but in this case, lower is better.
•Signal to Noise Ratio (SNR): This is really the key determinant to how good the performance of your wireless network is. This ratio is a comparison of the signal (the good radio waves) with the noise (the bad ones). SNR is measured in dB, and a higher number is better.
Many link test programs provide not only an instantaneous snapshot of your network performance but also give you a moving graph of your performance over time. This can be really helpful in two ways. First, if you have a laptop PC, you can move it around the house to see how your network performance looks in different parts of the house . . . or even just in different parts of the house. Second, it can let you watch the performance while you turn various devices on and off. For example, if you suspect that a 2.4 GHz cordless phone is killing your wireless LAN, turn on your link test and keep an eye on it while you make a phone call.
When you grow more comfortable with your wireless LAN — and start using it more and more — you can leverage these tools to really tweak your network. For example, you can have your spouse or a friend sit in the living room watching the link test results while you move the access point to different spots in the home office. Or you could use the link test with a laptop to find portions of the house that have really weak signals and then use these results to decide where to install a second access point.
134 Part III: Installing a Wireless Network