Wi-Fi Performance: What You Don't Know Can Hurt You

I recently stayed at a Bed and Breakfast that offered guests two unprotected wireless networks. There were no other Wi-Fi networks in the area, yet the signal strength in my room was poor and Internet access was slow and spotty.

Windows does a miserable job of reporting on some important aspects of wireless networks, so whenever I need to get a better picture of the Wi-Fi environment, I turn to the free, open source, inSSIDer program from MetaGeek. inSSIDer runs on Windows XP, Vista and 7, both 32 and 64 bit.

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Perhaps the most important aspect of wireless networks that inSSIDer reports but Windows omits, is the channel.

When setting up a new router, it is best to chose a channel used by the fewest (or none if possible) of your neighbors. inSSIDer makes this easy, as you can sort the display by signal strength. This lets you see the channels being used by the networks most likely to cause the greatest interference, and avoid them.

The 2.4GHz range used by most Wi-Fi networks offers offers 11 channels*. Of these, you should only use channels 1, 6 and 11 because they are the only ones that don't overlap. Some routers claim to be able to find the least used channel on their own.

Both networks at the Bed and Breakfast were using the same channel. No wonder the connection was flaky. The two networks were stepping on each others feet, most unnecessarily.

Who could have made such a basic mistake? According to the manager of the Bed and Breakfast, the Geek Squad set up the Wi-Fi networks.

Another nice thing about inSSIDer is that it shows signal strength as a number rather than bars. By default it updates the signal strength measurement every second, who knows how often Windows updates the displayed number of signal strength bars.

And, there is no need to watch the signal strength every second, inSSIDer graphs it, by network, over time. In the graph below, you can see that the red and green networks have the strongest signal, but that the red network provides a much more consistent signal.

While usually not necessary for debugging purposes, I love the fact that inSSIDer shows the manufacturer of each router that it finds. It can also display the Mac address of the router.

If you are interested in security and encryption then you need to know that what inSSIDer calls "RSNA-CCMP" is Latin for WPA2 with AES encryption - the most secure option available. WPA security is reported as WPA-TKIP, which again is technically more accurate. Signal strength too needs translating, it's called RSSI. The lower the number the better.**

inSSIDer is actively maintained and highly recommended. The Geek Squad? Not so much.

*Outside the US, there are a few more available channels.

**Update: August 31, 2010. Since the RSSI numbers are negative, this is not mathematically correct. To be clear, an RSSI value of -35 is a stronger signal than -75.

This story, "Wi-Fi Performance: What You Don't Know Can Hurt You" was originally published by Computerworld.

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