Wi-Fi networks use radio waves as the transport media for data. A wireless router translates data packets into radio signals which are decoded back to data packets by the receiving wireless adaptor.

Wireless routers work either in the 2.4GHz range or the 5GHz range for newer dual-band routers. The 2.4GHz range is split into 14 channels that are 22MHz wide. In the UK, channel 14 is not legally available.. Each channel is 5MHz from its neighbour, which means that each channel will overlap four neighbouring channels on either side.

To avoid interference from neighbouring Wi-Fi routers, configure your router to use a channel that is not in use by other by neighbouring Wi-Fi networks and one that does not have too many close-neighbouring channels in use. On Linux use:

iwlist wlan0 scan

to determine which channels are being used by neighbouring Wi-Fi networks.

The 54GHz range provides 42 possible channels, though only 18 are available in Europe. Because there are less domestic appliances working in the 54GHz range, and less Wi-Fi routers using this frequency, potential interference is reduced. The channels in the 54GHz range also have less overlap. However, the higher frequency bandwidth makes it more vulnerable to physical obstructions and therefore can reduce the strength and range of the signal.

Interference

Because Wi-Fi data is carried on radio waves, interference from other sources will impact on the performance of Wi-Fi connections.

Neighbouring Wi-Fi routers

Avoid using the same Wi-Fi channels as other Wi-Fi routers broadcasting within range of your network. Overlapping channels will also interfere with your signal

Other Wi-Fi devices

There are a multitude of wireless devices that can interfere with Wi-Fi signals: Video senders, baby monitors, security cameras, console controllers and speakers

Microwave Ovens

Can generate radio waves in the 24GHz spectrum

Bluetooth

Newer Bluetooth devices scan for free wavebands to minimise disruption, but older devices are not always so Wi-Fi friendly

Physical Obstructions

Thick walls, fish tanks and metallic materials can block or attenuate radio and therefore Wi-Fi signals

Power Cables

Power Cables emit electromagnetic radiation and potentially interfere with radio signals. Faulty electronic equipment can cause even greater problems

Mirrors

Can reflect and effectively block radio waves

Whilst you can run software on a computer to identify other Wireless networks that are potentially interfering with your wireless network, to identify other sources of interference you will need to use a RF spectrum analyser

Wireless Protocols

There are three main versions of the 802.11 standards currently in use for wireless networking:

802.11b

Provides a maximum theoretical throughput of 11Mb/s

802.11g

Released in 2003, and increased the theoretical throughput to 54Mb/s

802.11n

Ratified in 2009, and increased theoretical throughput to 150Mb/s, or 300Mb/s if channel-bonding is used. Speed increased mainly through use of antennas with multiple transmitter/receivers, refered to as MIMO antennas. Fastest speeds are available where 3x3 antennas are used - three for transmitting and three for receiving.