5GHz Wi-Fi DFS Dynamic Frequency Selection

Giganet's Wi-Fi routers broadcast the Wi-Fi signal across two separate frequency ranges 2GHz & 5GHz.

Your Wi-Fi name by default is broadcast on both. Your devices will connect to the best signal, and if they support 5GHz, and there's a good signal they will connect to 5GHz.

2GHz is the legacy and original frequency that Wi-Fi used, there's limited spectrum available, and typically this is used for legacy, low-bandwidth devices. It may also be used on newer devices in case the 5GHz signal is too weak, as one of the benefits of the 2GHz frequencies are that they can penetrate obstructions/objects more easily than 5GHz.

5GHz frequencies offer much greater spectrum and thus available speeds over Wi-Fi than 2GHz. Within the 5GHz frequency, there are multiple 5GHz channels that work in different frequency ranges.

• DFS not used: Channel 36 - 48 - (5170MHz - 5250MHz - 80MHz bandwidth)
• DFS required: Channel 52 - 64 - (5250MHz - 5330MHz - 80MHz bandwidth)
• DFS required: Channel 100 - 144 - (5490MHz - 5730MHz - 240MHz bandwidth)

What is Dynamic Frequency Selection - DFS?

Dynamic Frequency Selection (DFS) is a WiFi function that enables Wi-Fi routers/devices to use 5GHz frequencies that are generally reserved for (weather) radars. 

One main benefit of using DFS channels is to provide more Wi-Fi channels and allowing larger Wi-Fi channels, thus providing faster speeds and less interference.

However, there is one main drawback with using DFS channels, and that is if your Wi-Fi router detects a radar. If it does, then the Wi-Fi router will automatically switch to another frequency. When it switches, it may cause a loss in signal for 10 seconds, or more, thus you will lose your Wi-Fi signal on your devices.

If you were on a Zoom call, or online gaming, and a DFS Event occurred, your call or game will be interrupted. 

How do I know if it's a DFS Event causing the loss rather than the internet dropping out?

• If you lose the Wi-Fi signal from your devices, then this will most likely indicate a DFS Event rather than a broadband outage.
• If you log into the Customer Portal, you will be able to see your broadband session statistics. If the session has dropped coinciding with your interruption, then it will be the broadband rather than a DFS Event. 
• If hard cabled devices in the router continue to operate, then it's possible a DFS Event.

"False DFS Events"

A "false DFS event" is when the Wi-Fi router falsely detects radar. The Wi-Fi router may see an energy pattern that it believes is a radar, even though it is not. It is very difficult to determine whether or not radar detection events are "false".

What could be causing "False DFS Events"?

• The Wi-Fi router's signals are being strongly reflected back on itself.
  • E.g. is the Wi-Fi router located near a large metal object, or is there a hard object very close to the front of the router? If so, then there's a very strong likelihood that the Wi-Fi router's signal is bouncing off this object and being reflected back into the router. This can be known to trigger "False DFS Events".

What radars are impacted?

From Wikipedia

Prior to the introduction of Wi-Fi, one of the biggest applications of the 5 GHz band was the Terminal Doppler Weather Radar.[4][5] The decision to use 5 GHz spectrum for Wi-Fi was finalized in the World Radiocommunication Conference in 2003; however, the meteorological community was not involved in the process.[1][6] The subsequent lax implementation and misconfiguration of DFS caused significant disruption in weather radar operations in a number of countries around the world. In Hungary, the weather radar system was declared non-operational for more than a month. Due to the severity of interference, South African weather services ended up abandoning C band operation, switching their radar network to S band.[5][7]

Information on Met Office Weather Radars and locations here.

Giganet UltraHub 5GHz/ DFS settings and disabling/enabling DFS bands

1. Log in to your UltraHub router from your browser, usually this is https://192.168.1.1
   1. username: admin
   2. password: [access key] written on the rear of the router
2. Click on the cog icon on the Wireless tile
3. Select your WiFi name under the ACCESS POINTS 5GHZ section on the left hand section of the window

Use 5GHz DFS channels

• Auto Mode: All channels
• Channel:  Auto

Disable 5GHz DFS channels

• Auto Mode: Compatibility
• Channel: Auto