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Make The Most Of Available Wi-Fi Spectrum In An 802.11ac World

By Craig Mathias in · Technology · July 12, 2017
2.4 GHz may be yesteryear’s Wi-Fi darling, but you already paid for it. For the foreseeable future, many of devices on your network will require it. Certain solutions allow you to optimize its presence in an 802.11ac environment. Instead of ignoring 2.4GHz, and making your users suffer a poor Wi-Fi experience, why not embrace it? In this final post, we talk about making the most of the Wi-Fi spectrum that’s available for use.

Arguments as to which frequencies are better than others do have merit, but only up to the point where opportunity is lost. And not taking advantage of 2.4 GHz is just that, a lost opportunity. Here, then, are a few suggestions for how to get the most out of 2.4GHz:

1) Use the best tool for the job – It’s always desirable to operate any Wi-Fi device at the highest bandwidth it can support. By analogy, a fast device sharing a channel with a slower one is the same as a high-performance sports car being stuck behind a big truck.

The two were designed for very different purposes and very different applications. While cars and truck have to share the same roads, it’s not necessarily that way in the world of Wi-Fi. Putting older, slower traffic on 2.4 GHz is usually the way to go.

2) Set usage policies – And you may want to codify this in local policy. Any pending upgrades to higher-performance Wi-Fi should be performed, new purchases of slower products discouraged, and 2.4 GHz reserved for older devices, non-upgradeable devices, IoT, etc.

But, trust me – there will be a lot of this type of traffic for many years to come. Group applications with similar performance characteristics and demands on the same channel. If possible, phase out all Wi-Fi technologies prior to 802.11n, or at least have this as a goal.

Such will make the most of 2.4 GHz spectrum. And, while it’s a bit early to strategize the deployment of 802.11ax at 2.4 GHz, keep in mind that this will be a consideration for many within a few years.

3) Dual-radio means dual-band – Most enterprise-class APs today are dual-radio, and, of course, no one can deny that 5 GHz-only 802.11ac is the technology of choice for mainstream access in organizational settings.

But that doesn’t mean that both of those radios should be locked to 5 GHz-only. Sure, it’s possible to do a .11ac-only overlay, but such makes little sense as the older APs which must remain in place may not have the performance and features required and even essential today.

And, as is implied here, it will be desirable for some dual-radio APs to operate both radios at 5 GHz. Such APs are known as Dual 5 GHz access points due to their unique configuration mode which allows both the in-device radios to operate in the 5 GHz band. There are, however, other considerations around this mode of operation; see below.




4) Look for software configurability – It’s vital that one of those two radios be configurable for 2.4 GHz, for the reasons we’ve outlined in this series of articles. And it’s important that the configuration of that radio be under software control, so that network managers can easily configure and re-configure (manually or automatically) band assignments and other settings as traffic demands evolve.

5) And don’t forget the rest of the solution – Channels are precious resources, especially as they get wider with the consequence that fewer of them are available. Many APs, we’ve found, don’t deal with adjacent-channel interference very well and a degree of physical separation between APs operating on adjacent channels is thus required.

There are better solutions here, however, including very interesting and effective techniques involving antenna polarization and overall RF design. Speak with your vendor about these issues and their solutions.

And, while you’re at it, ask about the techniques they apply to automatic configuration of radio bands, channels, and transmit power levels, as well as load balancing and association optimization and throughput optimization via optimal airtime and traffic scheduling via quality- and class-of-service capabilities. And, of course, look for operation on 802.3af power even if you have 802.3at support; it never hurts to save energy.

There’s clearly a lot, then, to what seems like a simple set of considerations around 2.4 GHz. The bottom line regardless is that 2.4 GHz is going to be with us for a very long time, as it should be – spectrum is a precious, perishable commodity, and the increasing demands for Wi-Fi service being seen just about everywhere require making the most of every bit of it.

With the right equipment and management choices, though, such is easy, with all applications properly supported and all users going home – and coming back the next day – quite happy indeed.


Craig Mathias (@farpoint1)

Craig J. Mathias is a Principal with Farpoint Group, an advisory firm specializing in wireless networking and mobile IT. Founded in 1991, Farpoint Group works with technology developers, manufacturers, carriers and operators, enterprises, and the financial community. Craig is an internationally-recognized industry and technology analyst, consultant, conference and event speaker, and author. He currently writes columns for Boundless, Connected Futures, CIO.com, and various sites at TechTarget. Craig holds an Sc.B. degree in Computer Science from Brown University, and is a member of the Society of Sigma Xi and the IEEE.

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