Factors Affecting Wireless Signals

Because wireless signals travel through the atmosphere, they are susceptible to different types of interference than with standard wires networks. Interference weakens wireless signals and is therefore an important consideration when working with wireless networking.

Interference Types

Wireless interference is an important consideration when planning a wireless network. Interference is unfortunately inevitable, but the trick is to minimize the levels of interference. Wireless LAN communications are typically based on radio frequency signals that require a clear and unobstructed transmission path.

What are some of the factors that cause interference?

  • Physical objects Trees, masonry, buildings, and other physical structures are some of the most common sources of interference. The density of the materials used in a building's construction determines the number of walls the RF signal can pass through and still maintain adequate coverage. Concrete and steel walls are particularly difficult for a signal to pass through. These structures will weaken or, at times, completely prevent wireless signals.

  • Radio frequency interference Wireless technologies such as 802.11b/g use RF range of 2.4GHz, and so do many other devices such as cordless phones, microwaves, and so on. Devices that share the channel can cause noise and weaken the signals.

  • Electrical interference Electrical interference comes from devices such as computers, fridges, fans, lighting fixtures, or any other motorized devices. The impact that electrical interference has on the signal depends on the proximity of the electrical device to the wireless access point. Advances in wireless technologies and in electrical devices have reduced the impact these types of devices have on wireless transmissions.

  • Environmental factors Weather conditions can have a huge impact on wireless signal integrity. Lighting, for instance, can cause electrical interference, and fog can weaken signals as they pass through.

Some of the equipment and materials that can interfere with wireless LAN transmissions include

Equipment such as cordless phones or microwaves that produce radio waves in the 2.4 or 5.2GHz range

RF noise caused by two wireless LANs operating in close proximity

Outdoor broadcast television used by mobile television cameras

Uninterruptible power supply (UPS) devices

Large objects such as pine trees

Fluorescent lights

Heavy machinery

Heavy-duty motors found in elevators or other large devices

Plants and trees

Close proximity to smaller electric devices such as computers or air conditioners


This is not an exhaustive list, but it shows how wireless signals can be influenced by many different factors.