Legacy Open Mesh: Which Wifi channels should I use?

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Question 

Which WiFi channels should I use?

Environment

  • Open Mesh Access Points

Answer

WiFi supports two different bands: 2.4GHz and 5GHz. Each band is divided into channels. The bands and channels used for a network can greatly impact performance and reliability.

Channel Width

Channel width dictates the amount of bandwidth used within the radio spectrum during transmission. Using more bandwidth can lead to faster speeds, but also increases the chance of interference by others using the same area of the radio spectrum. WiFi bandwidth is measured in megahertz (MHz). The minimum channel width needed is 20 MHz. 40 MHz and 80 MHz channel widths are also supported on some devices.

HT/VHT

High Throughput (HT) mode is offered in the 802.11n standard, while Very High Throughput(VHT) mode is offered in the 802.11ac standard. 802.11ac is only available on the 5GHz band. If you have an 802.11ac capable access point, we recommend using VHT40 or VHT80 mode, as it can allow for better performance.

2.4 GHz

The 2.4 GHz band has limited available bandwidth. While it lists eleven different channels, each channel is only about 5 MHz wide. As noted above, WiFi needs a minimum of 20Mhz, so most of the eleven channels overlap into the same area of the radio spectrum.

For example, if you see someone already using Channel 1, and you decide to use Channel 2, you are not avoiding interference from Channel 1.

mceclip0.pngFigure 1: WiFi bandwidth overlap

  • The recommended channels to use on 2.4Ghz are Channel 1, 6, and 11. As figure 1, shows, these channels do not overlap into each other.
  • In general, 2.4Ghz should be considered a legacy band for older devices that do not support 5Ghz. It is often more crowded and offers lower performance than 5Ghz.
  • While you can run s 40MHz channel width on 2.4GHz, we do not generally recommend it due to the limited bandwidth available in the 2.4GHz band.
  • Lower frequencies generally travel further than higher frequency signals, so 2.4GHz may allow for further distance compared to 5GHz, but speeds will typically be significantly lower.
  • Open Mesh access points do not support Channels 12 - 14, and there is no planned support, as these channels are not allowed in North America.

5 GHz

5 GHz offers significantly more bandwidth than 2.4 GHz. All of the 5 GHz channels offered in CloudTrax support at least 20MHz channel width without overlap.

When using 5 GHz, we recommended using at least a 40 MHz channel width, as some client devices may not prefer 5GHz unless it offers a greater channel width than 2.4 GHz.

The following 5 GHz channels are supported with a 20 MHz channel width:

  • 36
  • 40
  • 44
  • 48
  • 149
  • 153
  • 157
  • 161
  • 165*

If using a 40 MHz channel width, the following channels' bandwidth is used:

  • 36 - 40
  • 44 - 48
  • 149 - 153
  • 157 -161

If using an 80 MHz channel width, the following channels' bandwidth is used:

  • 36 - 48
  • 149 - 161

*Channel 165 only supports 20MHz channel width.

This means the wider the channel width used, the higher the chances that access points will overlap each other in the same radio spectrum.

  • If you have a sparse network with a few access points and not a lot of users, such as a home or small office, consider using 80 MHz channel width to maximize per-client performance.
  • If you have a dense network with a lot of access points and clients, using 40 MHz channel width may help reduce the chance that access points and clients interfere with each other.

While 5 GHz offers greater performance, its distance is reduced compared to 2.4 GHz, and it may have a harder time penetrating some obstructions.

5 GHz also offers additional channels that require Dynamic Frequency Selection (DFS). DFS allows the access point to switch channels if it detects military or weather radar already in use on the channel. This functionality is not supported at this time.

Auto Channel Mode


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