The Road to Wi-Fi 6E Part 6: 6 GHz Spectrum
The available spectrum in Wi-Fi 6 is over twice as much as was available in the entirety of the 2.4 and 5 GHz range.
Published on December 2, 2022
This blog post is the sixth in a series of articles we’ll be presenting over the course of 2022 about Wi-Fi 6 (and 6E) – the current and future top-of-the-line Wi-Fi standards championed by the Wi-Fi Alliance. We’ll be discussing the history of the evolving standard of Wi-Fi, new features introduced in Wi-Fi 6 and 6E, applications beyond the commonly known consumer use cases, and much more. Additionally, we’ll be releasing a companion series of video interviews with Laird Connectivity experts, which you can find here.
6E’s Ocean of Spectrum, Newly Available for Wi-Fi
When the Wi-Fi specification was first published in 1997, it was a unique and innovative push to bring a standards-based, interoperable wireless protocol to devices that had no comparable offering. That initial 802.11 specification (now rebranded as Wi-Fi 0) was strictly in the 2.4 GHz range, with 3 nonoverlapping 20 MHz channels and an availability of a little over 80 MHz of spectrum. It was a limited range of frequency, and one that came with a good number of problems. Those who were around to remember will recall that wireless devices in this time suffered from interference from other wireless devices with less optimization, all competing for the same frequency space, to say nothing of sources of noise like microwave ovens that would fill the available spectrum with untenable noise. The 900 MHz range and the 2.4 GHz range were both difficult to operate in. It was a beginning, but it was a challenge.
A few years later, the 802.11a specification shifted to using the 5 GHz range, with 25 nonoverlapping 20 MHz channels and an availability of 645 MHz of spectrum. While some spectrum was shared with other applications, like radar systems, the newly available channels amounted to a huge increase. Later Wi-Fi standards made some changes to how this is used and allocated, notably in 2008 with Wi-Fi 4’s harmonization that allowed both 2.4 and 5 GHz operation. However, in essence, since 1999, no net-new spectrum has been made available to Wi‑Fi. For 20 years, Wi-Fi grew from a niche proof of concept to a dominant, essential, worldwide technology, with no new RF spectrum to help it deal with the challenges of its own success.
All of that changed in 2019, when the introduction of the Wi-Fi 6 specification took advantage of newly-available 6 GHz spectrum, made available first by the FCC in the US and gradually rolling out across the globe as allowed for use by Wi-Fi devices. This frequency is in the FCC’s UNII bands 5-8. Efforts are still ongoing, but accelerating, to make this frequency range available worldwide. Technically, this frequency is part of Wi-Fi 6E, the second wave of Wi-Fi 6, but by the time the transition is complete we’ll likely be referring to it as the completion of Wi-Fi 6.
But to describe it simply as “new spectrum” would be to bury the lead. The available spectrum in Wi-Fi 6 is over twice as much as was available in the entirety of the 2.4 and 5 GHz range. A total of 60 new non-overlapping 20 MHz channels, a total of 1200 MHz of new spectrum at most (depending on local regulatory agency approvals) is a humongous new opportunity for Wi-Fi. This is to say nothing of what it enables in terms of wideband channels: those non-overlapping 20 MHz channels can be combined into larger 40 MHz, 80 MHz, or 160 MHz channels that were present but scarce as recently as Wi-Fi 5.
In this post we’ll be looking more closely at those available channels in the newly-available spectrum, how 160 MHz channels have moved from technically possible to a practical reality, and the challenges and emerging availability of this new spectrum around the world.
6 GHz – Where Did It Come From?
The Wi-Fi 6 standard was split into two phases for good reason: While the initial Wi-Fi 6 spec could be moved on immediately, the bands and frequency were still in the process of being approved by regulatory bodies to support this next wave of Wi-Fi. In April of 2020, the FCC became the first global regulatory body to ratify the 1.2 GHz of unlicensed spectrum in the 6 GHz band (5.925 to 7.124 GHz, UNII 5-8) for Wi-Fi.
It’s not as if this frequency range emerged out of the ether. It’s been in use for many years by incumbent applications and technologies, and the introduction of Wi-Fi as an occupier of this spectrum took careful consideration of impact to those existing uses. To understand this complexity, one only needs to glance at a chart of the previous 2016 frequency allocation in the US (here’s a link to it on NIST's website). However, the relevant range of frequencies is shown here for convenience.
This is an incomplete picture of the
previously-allocated spectrum in the US, but the point is clear: This frequency
has been in use for some time. However, Wi-Fi’s relatively low power and
low-elevation use cases have been found to be non-disruptive to those existing
applications. And as such, the FCC approved the full range of 1.2 GHz
frequencies for Wi-Fi’s use.
This process is being repeated around the world with the FCC as a leader and a motivator for other regulatory bodies to adopt similar rules for the future of Wi-Fi. In January, the Wireless Broadband Alliance reported that 41 countries around the world already support the 6 GHz spectrum. They estimate that nearly 20% of all device shipments will support the 6 GHz band this year.
There are specific requirements (as always) to using those frequencies around the world. As regulatory bodies evolve their standards, some things are likely to remain the same: as with previous Wi-Fi standards, not every single channel in the spectrum is likely to be available everywhere around the world. Limits on Tx power means that even permitted use of a frequency range comes with stipulations about how loud transmissions can be (which impacts RF strength, link, and range). In particular, power limits on mobile devices will help to keep new WiFi 6 devices from interfering with incumbent applications.
Channels Galore – Small, Large, and Everything In Between
Here it would be helpful to return to an illustration we used in the past, showing what these channels look like:
As you can see even at a glance, the 6 GHz range pictured at the bottom is a massive expansion of available channels. But the second thing that becomes apparent is how limited the availability of channels, especially wide channels, was in 5 GHz (and virtually nonexistent in 2.4 GHz). This is something Wi-Fi 6E brings that is under-discussed: where 160 MHz bands were possible in Wi-Fi 5, their use was a practical impossibility. Only two were actually available, and the remaining channels left over in the 5.735 GHz – 5.835 GHz range only allowed a few remaining non-overlapping channels. Where that might be suitable in a limited network with few devices and only a few that required wideband channels, it remained impractical to nearly any large-scale or enterprise environment. Those wide channels just occupied far too much of the available frequencies to be truly useful. As a result, while multi-Gbit Wi-Fi networking was possible, it was rarely used. Most networks still used 20 and 40 MHz channels, never really seizing what was possible with 160 MHz channels.
The 6 GHz band introduces so much spectrum and so many available channels that now it’s actually practical to use them in a real-world setting without choking out the rest of the available frequency. Looking at that channel map now in hindsight, it’s easy to see how the introduction of 160 MHz channels was a huge feature addition but with limited applicability.
Specific Use Cases – More Bandwidth, Cleaner RF, Better Isolation
There are use cases that are obvious, as well as not-so-obvious, for this wide range of frequencies. The obvious ones are in the areas where high-bandwidth is a requirement, but there are also opportunities in applications where an ultra-clean RF environment protects the integrity of the application, as well as where reserving portions of spectrum is a security and operational concern.
· Medical – There are a great many applications, especially in medical, where an RF link is mission-critical and even life-critical. Take for example remote surgical instruments: there is an increasing adoption of surgical equipment operated remotely from a control station, where the link between the controls and the instruments is a Wi-Fi link. In these scenarios, any degradation of signal would mean loss of control of instruments – an unacceptable outcome. Similarly, health monitoring equipment is only as effective as its ability to stay connected and low-latency. Separating out devices like these onto non-overlapping channels with no chance of interference from local devices is the difference between good and great. And nothing but the best, in these use cases, is acceptable.
· Video Monitoring – In the past, video monitoring across multiple locations would often be serviced by CCTV. The CC in CCTV, of course, meaning closed circuit – wired. Now, it’s possible for video monitoring data to be sent entirely over Wi-Fi, but with that comes the high volume of data inherent in streaming video, especially at high resolution. Larger channels, OFDMA, and 1024 QAM all come together to provide traffic like this the Quality of Service it needs, with room to spare for other operations on the network.
· Network Logistics – With so much spectrum to go around, administrators can leverage Network Isolation to create multiple networks in the same space without interference. Consider for example a shipping center: it’s probably necessary to have Wi-Fi available for logistics equipment, handheld devices, office computers, and more, all within a relatively small space. To keep these different use cases from overlapping, an administrator may be well advised to create separate network SSIDs, each of which has access to a specific set of channels, all in one area. This has security implications, as well as performance applications: It might be a good practice to isolate sensitive data onto its own network, where other devices can’t access it. It might be helpful to provide an open SSID for guests or external personnel which doesn’t have access to resources containing sensitive information. The wide range of frequencies enables all of these networks to coexist, without interference, for a variety of business purposes.
This inclusion of 6 GHz spectrum in Wi-Fi is the biggest addition of available spectrum in two decades, and we’re only beginning to see the ways in which it might eventually be used. When 802.11 was first introduced, it allowed 2 Mbit/s and was designed for very limited use cases. But demand drove Wi-Fi to expand, and it might be fair to say that as Wi-Fi expanded it also encouraged adoption and innovation in that space. We’re now approaching another mountain peak with Wi-Fi, where it’s just becoming possible to see what’s over the horizon. The future of Wi-Fi applications will certainly be shaped by what’s being made possible today.
In our next and final part of this series, we’ll be looking at the common characteristics of Wi-Fi 6 devices from a hardware and design standpoint. Setting aside the features of Wi-Fi 6 itself, changes are on the way in terms of new and deprecated interfaces, configurable antenna options as supported by chipset manufacturers, and other factors like OS support, temperature range, form factor, and combination hardware like BT+Wi-Fi combo chipsets. We’ll look at what’s emerging, what’s available today, and what we expect to be available in the future as Wi-Fi 6 transitions into Wi-Fi 6E around the globe.
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