What Devices Cause WiFi Interference?

There are many things that emit signals in the same frequency spectrum that WiFi uses. At the bottom is a list of the most common things that might be bringing you down!

For best performance in a wireless environment, it is key that wireless devices are able to distinguish received signals as legitimate information they should be listening to and ignore any background signals on the spectrum. This concept is known as the Signal to Noise Ratio or SNR, which ensures the best wireless functionality. The SNR is the difference between the received wireless signal (that's carrying the data) and the noise floor (ambient background radiation). The noise floor is simply erroneous background transmissions that are emitted from either other devices that are too far away for the signal to be seen as modulated (carrying data), or by devices that are inadvertently creating interference on the same frequency. 

Optimal throughput rates and wireless performance, in general, can be improved by mounting APs correctly (high up on a wall or on the ceiling). Additionally, placing APs away from kitchens and other areas with high interference will also result in better performance. In a mesh environment, throughput rates will be significantly better with fewer hops to the gateway.

Here is a list that I created to help make you aware of common devices and electronics that can cause interference to the WiFi spectrum. 

Interference causing devices:

USB 3.0/3.1

Microwave ovens

Cordless phones

Bluetooth devices

Wireless video cameras

Outdoor microwave links

Wireless peripherals 

PDAs, cellphones

Zigbee - Wireless personal area network technology

Fluorescent lights


Other 802.11 networks - this is known as co-channel and adjacent channel interference. Since other 802.11 devices follow the same protocol, they tend to work cooperatively – i.e. 

two access points (APs) on the same channel will share the capacity of the channel.

Bad electrical connections can also cause broad RF spectrum emissions

Here are some devices that interfere with 5 GHz radios:

Cordless phones

Radar/doppler weather radar 

Perimeter sensors

Digital satellite