In radio networks, information is transmitted using electromagnetic radio waves. If there are other electromagnetic sources radiating energy in the same frequency spectrum, these emissions could disrupt wireless communication and, in extreme cases, prevent the operation of a WLAN. This may be caused by other radio systems and devices, such as Bluetooth, microwave ovens, or other WLAN networks. Denial-of-service attacks are also possible. For example, if certain control and management signals are sent repeatedly, this may hinder the availability of a radio network.