What Is Wi-Fi 7?

Great capacity, less latency—here's how IEEE 802.11be achieves both

4 min read
A purple circle with the number 7 in the middle. Curved purple lines radiate out from the circle to the left and right.
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New generations of Wi-Fi have sprung onto the scene at a rapid pace in recent years. After a storied five-year presence, Wi-Fi 5 was usurped in 2019 by Wi-Fi 6, only for the latter to be toppled a year later in 2020 by an intermediate generation, Wi-Fi 6E. And now, just a couple years later, we’re on the verge of Wi-Fi 7.

Wi-Fi 7 (the official IEEE standard is 802.11be) may only give Wi-Fi 6 a scant few years in the spotlight, but it’s not just an upgrade for the sake of an upgrade. Several new technologies—and some that debuted in Wi-Fi 6E but haven’t entirely yet come into their own—will allow Wi-Fi 7 routers and devices to make full use of an entirely new band of spectrum at 6 gigahertz. This spectrum—first tapped into with Wi-Fi 6E—adds a third wireless band alongside the more familiar 2.4-GHz and 5-GHz bands.

New technologies called automated frequency coordination, multi-link operations, and 4K QAM (all described below) will further increase wireless capacity, reduce latency, and generally make Wi-Fi networks more flexible and responsive for users.

Automated Frequency Coordination (AFC)

Automated frequency coordination (AFC) solves a thorny problem with the 6-GHz band in that, while Wi-Fi is the new kid in town, it’s moving into an otherwise well-staked-out portion of the spectrum. In the United States, for example, federal agencies like NASA and the Department of Defense often use the 6-GHz band to communicate with geostationary satellites. Weather radar systems and radio astronomers rely on this band a lot as well. And these incumbents really don’t appreciate errant Wi-Fi signals muscling in on their frequency turf. Fortunately, the preexisting uses of 6-GHz microwaves are largely predictable, localized, and stationary. So AFC allows Wi-Fi into the band by making it possible to coordinate with and work around existing use cases.

“We’re looking at where all of these fixed services are located,” says Chris Szymanski, a director of product marketing at Broadcom. “We’re looking at the antenna patterns of these fixed services, and we’re looking at the direction they’re pointing.” All of this information is added into cloud-based databases. The databases will also run interference calculations, so that when a Wi-Fi 7 access point checks the database, it will be alerted to any incumbent operators—and their particulars—in its vicinity.

AFC makes it possible for Wi-Fi 7 networks to operate around incumbents by preventing transmissions in bands that would interfere with nearby weather radar, radio telescopes, or others. At the same time, it frees up Wi-Fi 7 networks to broadcast at a higher power when they know there’s no preexisting spectrum user nearby to worry about. Szymanski says that Wi-Fi 7 networks will be able to use AFC to transmit on the 6-GHz band using 63 times as much power when the coast is clear than they would if they had to maintain a uniform low-level transmission power to avoid disturbing any incumbents. More power translates to better service over longer distances, more reliability, and greater throughput.

AFC is not new to Wi-Fi 7. It debuted with Wi-Fi 6E, the incremental half-step generation between Wi-Fi 6 and Wi-Fi 7 that emerged as a consequence of the 6-GHz band becoming available in many places. With Wi-Fi 7, however, more classes of wireless devices will receive AFC certification, expanding its usefulness and impact.

Multi-link Operations (MLO)

Multi-link operations (MLO) will take advantage of the fact that Wi-Fi’s existing 5-GHz band and new 6-GHz band are comparatively closer than the 2.4-GHz and 5-GHz bands are to each other. Wi-Fi access points have long had the ability to support transmissions over multiple wireless channels at the same time. With Wi-Fi 7, devices like cellphones and IoT devices will be able to access multiple channels at the same time. (Think about how you currently have to connect to either a 2.4-GHz network or a 5-GHz network when you’re joining a Wi-Fi network).

MLO will allow a device to connect to both a 5-GHz channel and a 6-GHz channel at the same time and use both to send and receive data. This wasn’t really possible before the addition of the 6-GHz band, explains Andy Davidson, a senior director of product technology planning at Qualcomm. The 5-GHz and 6-GHz bands are close enough that they have functionally the same speeds. Trying the same trick with the 2.4-GHz and 5-GHz bands would drag down the effectiveness of the 5-GHz transmissions as they waited for the slower 2.4-GHz transmissions to catch up.

This is especially clear in alternating multi-link, a type of MLO in which, as the name implies, a device alternates between two channels, sending portions of its transmissions on each (As opposed to simultaneous multi-link, in which the two channels are simply used in tandem). Using alternating multi-link with the 2.4-GHz and 5-GHz bands is like trying to run two trains at different speeds on one track. “If one of those trains is slow, especially if they’re very slow, it means your fast train can’t even do anything because it’s waiting for the slow train to complete” its trip, says Davidson.

4K Quadrature Amplitude Modulation (4K QAM)

There’s also 4K QAM—short for quadrature amplitude modulation (More on the “4K” in a moment). At its core, QAM is a way of sending multiple bits of information in the same instant of a transmission by superimposing signals of different amplitudes and phases. The “4K” in 4K QAM means that it is possible to superimpose more than 4,000 signals at once—4,096 to be exact.

4K QAM is also not new to Wi-Fi 7, but Davidson says the new generation will make 4K QAM standard. Like multi-link operations and automated frequency coordination, 4K QAM increases capacity and, by extension, reduces latency.

When Wi-Fi 7 becomes available, there will be differences between regions. The availability of spectrum varies between countries, depending on how their respective regulatory agencies have assigned out spectrum. For example, while multi-link operations in the United States will be able to use the channels at 5 GHz and 6 GHz, the latter won’t be available for Wi-Fi use in China. Instead, Wi-Fi devices in China can use two different channels in the 5-GHz band.

Companies including Broadcom and Qualcomm have announced their Wi-Fi 7 components in recent weeks. That doesn’t mean Wi-Fi 7 routers and cellphones are right around the corner. Over the next months, those devices will be built and certified using the components from Broadcom, Qualcomm, and others. But the wait won’t be too long—Wi-Fi 7 devices will likely be available by the end of the year.

The Conversation (3)
Gary Schafer31 May, 2022
M

"4K" doesn't mean "4096 signals at once"; it refers to the number of states, specifically the number of combinations of phases and amplitudes, that *one* signal can have. It means that, looking at the constellation of the modulated waveform, you'd see 4096 points (a 64 x 64 grid? I don't know.)

Mayur Sarode01 Jun, 2022
M

Thanks for the article, I am surprised not see a mention of 'preamble puncturing' as a flagship Wi-Fi7 feature.

Mayur Punamiya31 May, 2022
M

THANKS

Metamaterials Could Solve One of 6G’s Big Problems

There’s plenty of bandwidth available if we use reconfigurable intelligent surfaces

12 min read
An illustration depicting cellphone users at street level in a city, with wireless signals reaching them via reflecting surfaces.

Ground level in a typical urban canyon, shielded by tall buildings, will be inaccessible to some 6G frequencies. Deft placement of reconfigurable intelligent surfaces [yellow] will enable the signals to pervade these areas.

Chris Philpot

For all the tumultuous revolution in wireless technology over the past several decades, there have been a couple of constants. One is the overcrowding of radio bands, and the other is the move to escape that congestion by exploiting higher and higher frequencies. And today, as engineers roll out 5G and plan for 6G wireless, they find themselves at a crossroads: After years of designing superefficient transmitters and receivers, and of compensating for the signal losses at the end points of a radio channel, they’re beginning to realize that they are approaching the practical limits of transmitter and receiver efficiency. From now on, to get high performance as we go to higher frequencies, we will need to engineer the wireless channel itself. But how can we possibly engineer and control a wireless environment, which is determined by a host of factors, many of them random and therefore unpredictable?

Perhaps the most promising solution, right now, is to use reconfigurable intelligent surfaces. These are planar structures typically ranging in size from about 100 square centimeters to about 5 square meters or more, depending on the frequency and other factors. These surfaces use advanced substances called metamaterials to reflect and refract electromagnetic waves. Thin two-dimensional metamaterials, known as metasurfaces, can be designed to sense the local electromagnetic environment and tune the wave’s key properties, such as its amplitude, phase, and polarization, as the wave is reflected or refracted by the surface. So as the waves fall on such a surface, it can alter the incident waves’ direction so as to strengthen the channel. In fact, these metasurfaces can be programmed to make these changes dynamically, reconfiguring the signal in real time in response to changes in the wireless channel. Think of reconfigurable intelligent surfaces as the next evolution of the repeater concept.

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