WiFi Interference

Document created by shaw-jamess on Nov 27, 2013Last modified by shaw-james on Nov 23, 2016
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Understanding the Issue

WiFi allows an access point, like a modem or router, to share an Internet connection with client devices like computers, tablets, phones, and many other wireless-capable devices. Much like a cordless phone, the access point is the base station and your wireless device is the handset, capable of connecting to the network without wires providing it is within range of the base station.

 

The technology that makes wireless connections possible is based on protocols called 802.11x, with "x" being the specific generation of the wireless technology (with each generation offering more performance and range). You can think of the generations of WiFi as being similar to the generations of Apple's iPhone, with the iPhone 6 being succeeded by the 6S, the 7, and so on. When WiFi was first standardized, the protocols were 802.11b, 802.11g, then 802.11n, and more recently 802.11ac. These standards transmit and receive data via a radio connection between the access point and the client using two possible frequencies: 2.4GHz and 5GHz.

 

range of wireless devices from the access point

Access points of the 802.11b/g/n variety will operate in some capacity on the 2.4GHz spectrum, a frequency that is unlicensed and free to use for any wireless connection. This is where WiFi interference comes into play. As so many household items offer wireless capability, the 2.4GHz spectrum has become congested with competing signals from nearby devices. With 2.4GHz only offering 14 channels, and only three of those not overlapping in some way, the technology is not specifically designed to combat interference.

 

Resolving the Issue

Possible Causes of 2.4GHz WiFi Interference

Environmental Factors

Possible Remedies

Ideal WiFi Operating Range and Throughput

What is 802.11ac

 


 

Possible Causes of 2.4GHz WiFi Interference

 

The list of items that may cause WiFi interference is surprisingly long as the 2.4Ghz space is unlicensed and free to use for any wireless connection. Interference can be caused not only other nearby wireless networks but also any 2.4GHz operating devices and even high voltage devices that generate electromagnetic interference for any nearby networks. Please see the list below for more details.

 

Type of InterferenceDescription
Nearby Wireless NetworksYour neighbours likely all have wireless networks and any that operate on the same frequency will be causing interference and disrupting the performance of your local network.
Cordless phonesMany cordless phones operate on the same 2.4GHz space that is the host to most WiFi networks. If your network performance drops whenever your cordless phone is in use, consider switching to phones that operate on a different frequency, such as 900MHz or 1.9GHz DECT 6.0.
Baby MonitorsJust like cordless phones, most baby monitors operate on 2.4GHz and, given the constant connection between the monitor and the receiver, a baby monitor can affect the performance of your network.
MicrowavesOlder or poorly-shielded microwaves cause a great deal of electromagnetic interference at the 2.4GHz space, causing transmission problems for many wireless devices. Newer and modern microwaves are properly shielded and should not present any considerable problems to your network.
Wireless Security EquipmentWireless cameras and motion sensors operate just like baby monitors and will congest 2.4GHz networks. The latest generation of this type of equipment has the ability to connect to your access point (cameras and sensors are WiFi-ready) and will operate as a client and not congest your local network.
RadiosRadios and police scanners operate on a wide range of frequencies and can cause interference to any other nearby radio device. Proximity is likely the deciding factor in radio interference so don't have your access point located directly next to (or on) a radio transmitting device.
Monitors, TVs and ScreensMonitors and TV's, especially those that are not properly shielded, can cause interference for 2.4GHz networks (specifically channels 11-14). Don't place your access point directly next to (or on) a TV, monitor, or screen.
High-Voltage Household Appliances

High voltage or high-draw household items like laundry machines and air conditioning units cause electromagnetic interference. If you notice degraded network performance while operating a household appliance then your access point may be too close, or the appliance may not offer proper electromagnetic shielding.


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Environmental Factors

 

Apart from specific local devices causing radio interference on the same frequencies as your access point, there are environmental factors that can inhibit or disrupt the functioning of your home WiFi network. These factors include:

  • Brick, stone, and concrete walls - While not usually capable of blocking a WiFi signal, heavy stone, concrete, and brick will limit the effectiveness of a wireless signal.
  • Metal - The metal in walls or ceilings can have a dramatic effect on the range of a wireless network. This is why an access point may offer the best connection to devices on the same floor of your home. Floors and ceilings often have metal, wiring, conduits, ducting, and thermal shielding that can disrupt the radio signals that form your wireless network.
  • Lead paint - While uncommon, lead paint acts as a very effective shield for radio signals and can diminish or block a local WiFi network.


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Possible Remedies

 

While most of the interference experienced by your home network may be unavoidable (neighbour's networks, domicile construction, etc.), there are some possible remedies of which to be aware when planning for the addition of other wireless devices, or attempting to improve the performance of your home network:

  1. Use a dual band (simultaneous) 2.4 and 5GHz router. The 5GHz range is still a newer frequency so it is less used in many congested areas. Look for wireless routers marked as 802.11n. For best results, upgrade your entire network to 802.11ac, which operates exclusively on 5GHz and should bypass most local interference.
  2. Allow your modem/router to automatically manage channels to switch away from congested frequencies. While forcing your access point onto a fixed channel can be quite effective in some situations, any modern access point has the ability to automatically move to a different channel if the current channel is experiencing too much interference.
  3. Line of sight is always better. Don't put your 802.11b/g/n access point on the floor, this wastes half of its 360 degree field of range (see image below).

best place to put your wireless access point at home

  1. 802.11n is not a guaranteed solution, as this standard relies on sending multiple signals (using both 2.4 and 5GHz) which can perform poorly in heavily congested areas.
  2. Use WiFi devices whenever possible. Some home wireless devices like baby monitors and security equipment use their own point-to-point connections and can cause a great deal of interference to other local wireless networks. By using WiFi devices, all clients connect to the signal and network provided by your access point.


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Ideal WiFi Operating Range and Throughput

 

The effective range and data rate of an access point is based on ideal conditions, such as those set up in a laboratory where one can isolate the connection against any other local interference. In a scenario with no active interference (from other wireless devices), and no environmental interference (such as walls, ceilings, and floors), this would be the ideal standardized performance from a wireless access point to a single client connection:

 

Wireless ProtocolData RateApprox. Range
802.11b (2.4GHz)11Mbps150-300 ft
802.11g (2.4GHz)54Mbps100-200 ft
802.11n (2.4 and 5GHz)54+Mbps80 ft
802.11ac (5Ghz)430+Mbps80+ ft

 

As later generations of WiFi technology offered enhanced data rates, their operating range decreased. As more power is used to enable a greater amount of bandwidth, the signal range is diminished. This would explain why a single access point cannot provide adequate coverage for a large home, especially in ancillary areas like yards, garages, and basements. With the vast majority of access points operating on 802.11g, effective range is at best 200 ft (before you factor for any of the above sources of interference). In actual use, most home access points are capable of providing a network to a handful of devices over a large condominium or a small home. Larger applications may require multiple access points and newer technology (such as 802.11ac) to expand the coverage and performance of the network.


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What is 802.11ac

 

The latest WiFi Protocol, 802.11ac, operates exclusively on 5Ghz and should experience much less interference, as the 5GHz space is less congested. Furthermore, 802.11ac offers beamforming in which the signal from the router is focused towards the client connection (unlike the above diagram where the signal is a 360 degree bubble from the access point). To access the enhanced speed, range, and features like beamforming, you must be using not only an 802.11ac access point, but also 802.11ac clients. As 802.11ac is still a newly certified standard it is not built into most devices on the market today. Over time, 802.11ac access points will drop in cost and the technology will become the default in client devices.

 

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Related Articles

 

Wireless Device Quick Setup Guide

How to Change the Channel On Your Shaw Wireless Modem

Hardware Information Cisco DPC3835 Internet Modem

Hardware Information SMC D3GN Internet Modem

 


 

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