airMAX - Selecting the Best Channel Width


Overview


This article describes the different channel widths and guides users to choose the best one for different deployments.


Table of Contents


  1. Introduction
  2. Narrow Channels
  3. Medium Channels
  4. Wide Channels
  5. Responsible Use of Spectrum
  6. Related Articles

Introduction


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For users that are new to the airMAX world, it is highly recommended that they first read our  airMAX - How to Use airView to Find the Best Channel article that explains how to select the best frequency and channel width for outdoor links. 

Our airMAX AC products follow the same basic rules, but there are some details that should be taken into account to get the very best out of the wireless link. In the following sections we will describe the different characteristics of channels, depending on their width and which is best for each scenario.


Narrow Channels


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Narrow channels are those equal or narrower than 20MHz. They offer better radio sensitivity and better Signal-to-noise ratio (SNR), making them less susceptibility to noise, thus having better reliability, but "lower theoretical throughput". I emphasize "lower theoretical throughput", because even though they have less bandwidth available, which in theory would reduce the maximum throughput, in most cases the highest SNR level helps to achieve higher data rates and a more stable performance than wider channels.

However, in 802.11ac these channels will only be able to negotiate up to 11ac MCS8 (2 spatial streams) data rates, which could be an important factor if you need the highest throughput and your link has a very high signal strength. Narrow channels are ideal for video surveillance, VOIP and WISPs offering medium-speed plans using PtMP systems.


Medium Channels


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Medium channels (between 30MHz and 50MHz) are probably the best choice for most cases where very high throughput is needed and the area's interference level is low. It's usually a good alternative for PtP networks and offer a balanced option between narrow and wide channels. 

It is important to note that 30MHz channels only support 11ac MCS8 (2 spatial streams) rates. On the other hand 40MHz and 50MHz channels support up to 11ac MCS9 (2 spatial streams) data rates. Medium channels are ideal for high-performance PtP links and high-speed PtMP networks.


Wide Channels


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Wide channels (60MHz and 80MHz) offer the ultimate throughput experience. They will support up to 11ac MCS9 data rates and throughput over 450Mbps. Unfortunately, these channels are very susceptible to interference because of the bandwidth used. They are only recommended when you have a very high signal strength and low interference (you can view how clean the RF spectrum is in your area using airView). Wide channels are ideal for highest-performance PtP links. Not recommended for PtMP networks.


Responsible Use of Spectrum


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Our airMAX devices use an unlicensed band, which is shared by all users in the 5GHz. Your interference could affect other users. In order to reduce the impact (and increase your network reliability) we highly recommend you to use narrow channels in situations where you don't need the highest throughput. A good example of this would be video surveillance systems where a 10MHz channel is more than enough to stream full 1080p video.

ATTENTION: Please check your local regulations, different countries may have different EIRP limits for certain frequencies and channel widths.

Related Articles


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airMAX - How to Use airView to Find the Best Channel