The process of transmitting and receiving radio and laser signals through the air makes wireless systems vulnerable to atmospheric noise and transmissions from other systems. In addition, wireless networks can interfere with other nearby wireless networks and radio wave equipment. Interference can take on an inward or outward direction.
A radio-based LAN, for example, can experience inward interference either from the harmonics of transmitting systems or from other products using similar radio frequencies in the local area. Microwave ovens operate in the S band (2.4GHz) that many wireless LANs use to transmit and receive. These signals result in delays to the user by either blocking transmissions from stations on the LAN or causing bit errors to occur in data being sent. These types of interference can limit the areas in which you can deploy a wireless network. Newer products that utilize Bluetooth radio technology also operate in the 2.4GHz band and can cause interference with wireless LANs, especially in fringe areas not well covered by a particular wireless LAN access point.
The other half of the issue, outward interference, occurs when a wireless network's signal disrupts other systems, such as adjacent wireless LANs and navigation equipment on aircraft. This disruption results in the loss of some or all of the system's functionality. Interference is uncommon with wireless LAN products operating in the public spread spectrum bands because they operate on such little power (less than 1 watt). The transmitting components must be very close and must be operating in the same band for either one to experience inward or outward interference.
When implementing a wireless LAN, be sure to investigate the potential for inward and outward interference as part of an RF site survey of the location where the wireless LAN will operate.