Site Surveys – CompTIA Security+ SY0-401: 1.5

Before installing a new wireless network, you’ll probably want to perform a site survey. In this video, you’ll learn why a site survey might be one of the most important parts of your wireless network installation.

<< Previous Video: Antenna TypesNext: VPN Over Open Wireless Networks >>

Implementing a wireless network isn’t something that you can simply click a button and have the best possible performance. You have to understand the wireless spectrum and what’s happening currently before you can implement a new wireless device into that environment. One of the things you can do is to do a site survey. You need to understand what the existing wireless landscape happens to be. You can use scanning tools on a device or some specialized spectrum analyzers that can really tell you exactly what’s going on with all of the radio signals in this particular area. It’s very common then to initially try to understand where all of the other access points might be. You might see these pop up in an SS ID list or you might use to specialize scanner, like this one, to be able to understand where the access points are.

You may not even be in control of every single one of those. You may be in an office environment where there’s different companies on different floors, so all of the wireless networks may not necessarily be something that you are able to change. That means that you’ll have to work with what’s currently in place and try to get your wireless network to have the best possible performance regardless of what happens to be a round you. This means that you’ll want to do as much research as possible. You’ll want to walk around with your wireless scanners or spectrum analyzers and really understand what all of the different radio signals are in that area. You may also want to take into consideration other devices that might cause interference like microwave ovens. This needs to be considered as well so that you can properly place the antennas for your access points. And since the only constant is change, you’ll want to periodically recheck all of the settings that you have. Perhaps show up again and do another site survey, and make sure that there wasn’t a new access point or another device that might be conflicting with the frequencies that you’d like to use for your wireless network.

One of the keys for us on a wireless network is to have our own frequencies in use. If there are other access points in the area, let’s make sure that they’re running on completely different frequencies that are not going to overlap with the ones that we would like to use. For an example, let’s look at the implementation of an 802.11b network, although the same idea applies to all of the different wireless types. And we have a floor plan here that shows us where all of the different devices are, and the different offices, the different conference rooms, and let’s overlay what a layout might look like of wireless access points. So in this particular case, I’ve overlaid where the signals might be for these Omni directional antennas. And you’ll notice what I’ve tried to do is put channels on to this that would not overlap or interfere with the channels that are directly next to us. And for this particular case, we’re using 802.11b and we know that channel one, channel six, and channel 11 are completely separate channels that do not overlap with each other. So we’ve chosen to use those three and notice that we’ve interlace them so that no channel one is ever going to conflict with another channel one. Channel six would not conflict with another channel six, and channel 11 would not conflict with another channel 11. You have other frequencies and other channel choices depending on the wireless type that you’ll be using, but you’ll want to use the same type of methodology, so that when you implement your wireless network, you’re not going to have any problems with interference with the signal.