Multi-link tech and big spectrum gains will drive Wi-Fi 7

Wi-Fi 7 (802.11be) will take advantage of the 6GHz spectrum recently allocated to unlicensed wireless technology.
  • Jon Gold (Network World)
  • 15 March, 2022 05:45

Even as businesses continue to make the move to Wi-Fi 6, standards bodies and contributor companies are hard at work creating Wi-Fi 7, or 802.11be, the next generation of Wi-Fi technology that promises even greater capabilities than the latest in unlicensed wireless tech.

A combination of new technologies focused on efficient spectrum usage and the recent FCC decision to make a huge swath of the airwaves available to Wi-Fi will push Wi-Fi 7’s peak throughput numbers as high as 40Gbit/s in certain configurations.

Dorothy Stanley is the chair of the IEEE SA 802.11 working group. She said that the focus of the new standard is extremely high throughput, which is accomplished, in large part, by the wider channels enabled by the new availability of 6GHz spectrum (5.925 GHz to 7.125 GHz).

“If you look at the channels that are used over the air, they’re usually multiples of 20[MHz],” Stanley said. “What’s new in [Wi-Fi 7] is the definition of a 320MHz-wide channel. Due to the availability of spectrum, the ability to use that is only really in the 6GHz band.”

The potential for 40Gbit/s speeds will only be realised with those 320MHz-wide channels that reside in the 6GHz band, but Wi-Fi 7 will also operate on 2.4GHz and 5GH frequencies, just like earlier generations of Wi-Fi. The goal for general-use Wi-Fi 7 is 30Gbit/s, Stanley said.

These advancements are being driven by several key use cases, according to Qualcomm senior director of engineering Andy Davidson, who named edge and cloud applications, VR/AR and cloud gaming as the in-demand services that even Wi-Fi 6 is unable to handle elegantly.

There’s an array of new technological innovations that will contribute to making those speeds a reality, but one that might make the biggest difference to everyday feeds-and-speeds improvements is called multi-link, he added.

Davidson said that typical Wi-Fi APs operate on one channel at a time in a given frequency range, so one channel in the 2.4GHz range, one in 5GHz. That’s about to change, with Wi-Fi 7. “You’ll be able to connect to two channels at once and get the advantage of leveraging them both,” he said.

Multi-link will come in two distinct flavours. The first is alternating multi-link, where one of the two linked channels sends data down to the client and the other sends it up to the AP. That’s good for throughput on its own, but the other mode, simultaneous multi-link, will also help address latency issues, by making each paired channel send both up and down at the same time.

The idea here, according to Davidson, is avoiding congestion, since there’s less likely to be interference on two channels at the same time. That’s central to the

“Latency’s largely about congestion, and we find [simultaneous multi-link] really addresses those long-latency events,” he said.

Avoiding interference is a key concern in WI-Fi 7, so much so that there’s work afoot in the industry to create frameworks for automated frequency coordination, so that spectrum can be used by multiple players simultaneously with minimal interference risk, according to Stanley.

“Databases that coordinate and look up the frequencies in a given area [will be available] when you want to enable higher-power operation,” she said.

The timeline for these new features hitting the shelves is dependent on close coordination between the major vendors and the IEEE SA. Generally, equipment from a new generation of Wi-Fi gets offered for sale significantly ahead of the finalisation of the standard, but exactly how far ahead is a matter of some debate.

“For example, the 11n standard was finally published in 2009 and products hit the market in 2007,” Stanley said. “For [Wi-Fi 6], the standard was ratified and published in 2021, and the Wi-Fi Alliance started publishing it in 2019.”

While the current projected completion date for the standard is mid-2024, she noted, that type of projection is frequently a little optimistic. “I think it’ll finish sometime in 2025,” Stanley said.

Qualcomm’s Davidson is slightly more bullish, saying that pre-standard Wi-Fi 7 gear could become available within a year, driven in part by what he sees as increasing willingness from organisational users to dive into new Wi-Fi tech as soon as it rolls out.

“What we’ve seen in WI-Fi 6 is that enterprises are willing to work more quickly than they have before,” he said. “We’ll likely see the same thing with Wi-Fi 7.”