RF Interference from external sources

We often are contacted by people that have issues with poorly performing networks, asking us the reasons why and if we can assist. There are a number of reasons that WiFi networks can underperform, and I don’t have the time or space here to cover off all of the reasons, bad design is a key reason, but the topic of this blog will be external RF interference.

The 2.4 Ghz spectrum

Within the 2.4Ghz spectrum there are a number of devices and systems that can interfere with a 2.4Ghz wireless network. Cordless phones and baby monitors often use the 2.4Ghz frequency, causing interference to 802.11b,g,n networks, this can result in a decrease in the networks speed, or sometimes the signal from an access point can be totally blocked.

Bluetooth devices also operate on the 2.4Ghz spectrum, but as they only use a 1Mhz wide band, and change channels up to 1600 times a second they are not one of the key issues for WiFi interference.

Microwave ovens also operate in the 2.4Ghz band – emitting very high power over the entire spectrum used by 802.11b,g,n – these devices should be shielded, stopping leaking of the RF signal – however older devices can emit interference, if you're experiencing issues with your network around lunch time – then the microwave oven should be your first port of call!

Many other sources of interference exist – such as Zigbee devices, Video senders and others, any one of these could affect the performance of the network.

Spectrum Analysis

A key tool in tracking down interference, is a spectrum analyser, this software(in conjunction with either a built in wireless card – or external wireless "dongle" will allow you to view the wireless spectrum, and track down the interference. Using a directional antenna can also assist in locating the actual source of the interference.

DigitalAir Wireless offer a range of wireless health check services – external interference is one fo the many things that could be affecting your network, however there are many other factors. A professional wireless health check will give you all of the data that you need to make an informed decision.