Legacy Open Mesh: How does channel width affect my network?

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Question

How does channel width affect my network?

Environment

  • Datto Networking

Answer

Channel width specifies how much bandwidth your radio is using within the available spectrum. Using more bandwidth can speed up your wireless network, but it can also cause more interference for adjacent access points. There are several things to consider before increasing the channel width.

On 2.4Ghz, access points typically use 20Mhz wide channels. On 5Ghz, the access points will typically use 40Mhz wide channels for 802.11n models, and 80Mhz wide channels on 802.11ac models.

Channels that are 20Mhz wide are typically known as "narrow channels", while those that are wider than 20Mhz are known as "wide channels". The 802.11n specification uses High Throughput(HT) and Very High Throughput(VHT) designations.

  • Narrow channel = 20 Mhz / HT20
  • Wide Channel = 40 Mhz / HT40
  • 802.11ac Wide Channel = 80 Mhz / VHT80

 Consider the questions below, before enabling wide channels on your network.

1. Do you have many other wireless devices under Manage > Site-Survey?

Even if all of your Open Mesh APs have good channel selection, interference may come from other radios in your wireless environment.

2. Do you use multiple APs that can hear each other?

Wide channels make managing overlapping channels much more difficult.

3. Are you using repeaters?

Wide channels can decrease the stability of repeaters.

4. Are your clients' RSSI values good enough to use wide channels?

When using wide channels, a client will need 3db better RSSI to keep the same modulation rate as narrow channels.

5. Are you using 5 Ghz?

It is typically recommended to use at least 40Mhz wide channels on 5Ghz. As 5Ghz is generally less crowded, and performs better than 2.4Ghz. Some client devices may not connect to the 5Ghz band unless it has a wider channel than the 2.4Ghz band.


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