What interference might exist in a WLAN and how seriously can they affect a WLAN?

   What interference might exist in a WLAN and how seriously can they affect a WLAN?

2.4 GHz ISM band is reserved for the use in industrial, scientific and medical fields other than telecommunications. Devices that can use the 2.4 GHz band include microwave ovens, cordless phones, and Bluetooth devices. Interference severity of cordless phones, microwave ovens (within 3 meters), and Bluetooth devices such as laptop and PDA are in descending order.

Compared with the 2.4 GHz band, the 5 GHz band has less interference. Interference in the 5 GHz band includes radar, wireless sensors, digital satellites, wireless ATMs, and software-defined radios.