What is Wi-Fi 7?

Wi-Fi 7 is the latest generation of Wi-Fi. As with most technologies, a bigger number = better. Wi-Fi 7 isn’t that simple though.

The underlying standard is known as 802.11be, and work on Wi-Fi 7 officially started back in May 2019. The main goal of Wi-Fi 7 is to increase throughput, reduce latency, and leverage all of the available spectrum, ranging from 1 GHz up to 7.25 GHz.

The initial draft of the Wi-Fi 7 standard landed in March 2021, and the Wi-Fi Alliance launched the Wi-Fi 7 certification program on January 8th, 2023. Manufacturers started producing their first products years ago, based on early draft versions of the standard, just like they did with Wi-Fi 6 and past major revisions. Qualcomm, Broadcom, and TP-Link have been aggressive with rolling out early hardware, and now Ubiquiti and the rest of the industry have joined them.

Key Wi-Fi 7 features

• 320 MHz bandwidth and more efficient utilization of non-contiguous spectrum
• Increases maximum modulation to 4096-QAM (4K-QAM)
• Multi-band/multi-channel aggregation and operation, including contiguous and non-contiguous 320/160+160 MHz and 240/160+80 MHz bandwidth
• 16 spatial streams and Multiple Input Multiple Output (MIMO) protocol enhancements
• Multi-Access Point (AP) Coordination (e.g. coordinated and joint transmission)
• Enhanced link adaptation and retransmission protocol (e.g. Hybrid Automatic Repeat Request (HARQ))
• Frame formats with improved forward compatibility
• Enhanced resource allocation in OFDMA
• Reduces airtime consumption with optimized and implicit channel sounding, and a more flexible preamble puncturing scheme
• Supports direct links, managed by an access point.
• Integrates Time-Sensitive Networking (TSN) IEEE 802.1Q extensions for low-latency real-time traffic

The Goals of Wi-Fi 7

One of the big themes of Wi-Fi 7 is the same as most new generations of Wi-Fi: how can we make it faster and more reliable?

Until now, Wi-Fi has increased speed and capacity by:

• More complicated modulation to send more data at once
• Wider channels to use more spectrum
• MIMO to use multiple antennas at once

Unfortunately, we are reaching to point of diminishing returns with increases in modulation, channel width, and MIMO. Despite this, Wi-Fi 7 still pushes those forward, increasing maximum modulation to 4096-QAM, channel width to 320 MHz, and MIMO up to 16 spatial streams. The numbers are bigger than ever, but that’s not enough.

4096-QAM offers at most a 20% increase over 1024-QAM, but both of them only work over short distances, in ideal conditions. They require such a high signal-to-noise (SNR) that they are only attainable within a few feet of an AP. Higher data rates deliver more data but are less reliable, so clients need to balance between speed and reliability.

Wide channels have been a big topic since the introduction of Wi-Fi 6E and the addition of 1200 MHz of spectrum in the 6 GHz band. Wi-Fi 7 increases the maximum channel size to 320 MHz, compared to 160 MHz in Wi-Fi 5, 6, and 6E. Double the spectrum equals double the data rates and double the potential throughput. It also doubles the noise and chance for interference, making them challenging to use in real-world networks, particularly those with a lot of clients or density. 320 MHz channels aren’t supported in many countries yet either, but availability will continue to expand.

Wi-Fi 7 will permit up to 16 spatial streams, but those will require large antenna arrays, more expensive internals, and a ton of power. If history is anything to go by, MIMO beyond 4 spatial streams is unlikely to be found in anything beyond high-end access points, and most clients are likely to stay with 2 spatial streams.

With these increases costing more and delivering less, new techniques are needed to see big gains in performance. Wi-Fi 7 does this in several ways, but one of the biggest is with Multi-Link Operation.

The Promise of Multi-Link

Multi-Link Operation (MLO) allows for the aggregation of multiple bands or channels. With MLO, Multi-Link Devices (MLDs) can simultaneously use the 2.4GHz, 5GHz, and 6GHz bands. This can be in the form of load balancing, or aggregation. This allows for higher overall speeds, and reduced latency and congestion for all connected clients.

In previous Wi-Fi standards, clients connect to one band at a time and can switch between them. This introduces overhead when changing frequencies, leading to delays and precious milliseconds being wasted. When load balancing, a client can choose the fastest or least busy channel. With aggregation, latency can be as low as 1 ms when switching bands. This should improve performance overall, especially in real-time audio, video, or gaming applications.

There are several different types of MLO, including:

• Multi-link single radio (MLSR) which can transmit and receive over one radio at a time
• Enhanced MLSR (eMLSR) which enhances MLSR with a reduced function radio to choose the best link
• Nonsimultaneous TX and RX multi-link multi-radio (Non-STR MLMR), which can transmit and receive over 2 or more radios, but with time and frequency separation constraints
• STR MLMR, which can simultaneously transmit and receive over 2 or more radios

A Splash of Cold Water

There are many other details about MLO that I didn't cover here, and many other features of Wi-FI 7 that address issues and increase performance. The new features in Wi-Fi 7 are exciting, but for now, they are mostly a technical curiosity. I am excited to watch the continued development and rollout of Wi-Fi 7, and get my hands on a U7-Pro to do some testing.

While Wi-Fi 7 is in its early adopter phase, we are going to see a lot of hype and marketing designed to make us think we need it, and we need it right now. I’ll never agree with that mindset, especially when it comes to Wi-Fi standard revisions.

For the vast majority of users, Wi-Fi 5 and Wi-Fi 6 offer more than enough speed and reliability. For the applications most of us use, on the devices most of us have, we’re not going to see a massive jump in experience. What excites me the most is projecting into the future, when multi-link and Wi-Fi 7 become common.

Progress is good, but with all things Wi-Fi, patience is rewarded. Don’t rush out and get the first Wi-Fi 7 equipment you see, let the standard come down to you. That being said, it’s always fun to look out to the edge of the wireless frontier. Welcome to Wi-Fi 7.

References and Further Reading

• IEEE Explore: Multi-Link Channel Access in IEEE 802.11be Networks
• Intel: Wi-Fi 7 and Beyond PDF
• MediaTek Wi-Fi 7 whitepaper detailing key advantages of Wi-Fi 7
• MediaTek: Discover why MLO is a key driver of Wi-Fi 7 performance