WLAN Foundations: Locating Interference and What to do once you find itBy CWNP On 01/07/2014 - 31 Comments
How to locate, and remedy, wireless interference.
Written By: Tom Carpenter
Many items can cause interference with your WLAN communications. These include cameras, rogue APs, microphones, headsets, mice (though very limited and localized, and no, not the furry kinds), phones, microwaves, and specialty equipment.
Incidental energy may also be generated from some electric motors. They are not designed to radiate RF signals, so it is called incidental.
Locating the interference can be as simple as walking around with a spectrum analyzer until the signal is the strongest. More advanced techniques can be used in WLAN management software as well.
Once you've found the spot with the strongest signal, you know the interfering device is nearby. At this point you can use the excellent interference locators that are built-into every human being: the senses.
Look around. You'll probably spot the device quickly. Look for any of the following:
• Small boxes plugged into wall power. These boxes may be RF signal generates being used to intentionally interfere with your network.
• Small APs, also known as pocket APs, which take very little space. They will likely be connected to an Ethernet port too.
• Motors, microwaves and elevators. These devices may generate unintentional RF interference.
• Neighboring WLANs.
If the interference source is within your property, you can either remove the device or change channels to work around it. If the source is a neighboring WLAN or other equipment used by neighboring companies, careful negotiations are in order. Keep the following in mind:
• As long as the neighboring WLAN or device is operating within the FCC regulations, you cannot force the owner to adjust it in any way.
• Calm requests usually provide the best results. Remember the ancient wise saying, a gentle response defuses anger.
• Try everything in your power first. If you can adjust the channel on your WLAN, do it. If the interference problem is resolved, you may want to let the neighbor know that you've solved it.
The reason for that last recommendation is simple. If your WLAN is being interfered with by your neighbor's WLAN, guess what, your WLAN is interfering with the neighbor's as well. This fact means that your adjustment has probably just solved some problems for the neighbor. Informing them of such may generate good will for that future scenario where you need them to change their wireless settings (or help you in some other way). In a license free world, negotiation skills are key and the law of reciprocity is always helpful.