What is WiFi 6?

Tech laity calls it WiFi 6 or High Efficiency WiFi. Tech geeks call it IEEE 802.11-ax-2021 or merely 802.11ax. WiFi 6, as one may assume, supplants the previous 802.11ac-2013 (WiFi 5) WLAN standard. WiFi 6 delivers much-improved performance and significantly faster speeds compared to its predecessor.

Source: Wi-Fi Alliance

While WiFi 5 delighted users with its increased efficacy over previous IEEE WLAN standards (think 802.11g/n, now called WiFi 3/WiFi 4), this sixth generation of WiFi is much better. Perhaps you know WiFi 5 is limited to just the so-called 5 GHz (a misnomer since actual channel wavelengths vary between 5.18 GHz to 5.7 GHz) band. WiFi 6 provides wireless device interoperability using spectrum between 1 GHz and 6 GHz (6 GHz in the U.S. means spectrum within 5.925 GHz and 7.125 GHz).

The IEEE approved the 802.11ax-2021 standard on 9 February 2021. But before introducing WiFi 6-compatible devices into your organization, you should know of crucial decisions the IEEE 802.11ax task group made regarding WiFi 6's rules of operation in the 6 GHz band. Also, learn about improved technical specifications that make WiFi 6 superior to its ascendants, particularly when connecting to IoT devices.

A sidebar: you may have seen references to WiFi 6 and WiFi 6E. What's the difference? WiFi 6E has all the features of WiFi 6 but also broadcasts over the 6 GHz band; WiFi 6 doesn't. Yes, WiFi 6E is a marketing tool of the Wi-Fi Alliance but unlike AT&T's 5GE (which is naught but rebranded 4G LTE-A), WiFi 6E is actual WiFi 6, but better than the original. In this article, WiFi 6 alludes to WiFi 6E.

Let's start by watching the following YouTube video produced by Techo Dad Life: https://www.youtube.com/watch?v=PWSAHOYjgh8

WiFi 6 Performance Benefits

WiFi 6 offers much faster data rates than WiFi 5. WiFi 6 is touted to reach speeds of up to 9.6 Gbps; WiFi 5 theoretically tops out at 3.5 Gbps. Practically speaking, your devices don't receive these speeds in "the real world." But WiFi 6's gigabit speeds are still faster than you'll probably ever need. More importantly, WiFi 6 simultaneously connects to more devices without exacerbating network interference compared to WiFi 5.

Speaking of network congestion, WiFi 6 utilizes 1,200 MHz in the 6 GHz band. By contrast, the 2.4 GHz and 5 GHz bands combined equal only 400 MHz. So WiFi 6 users exploit a bigger data pipe — 2,000 MHz in total. Also, with WiFi 6's vastly improved MU-MIMO, OFDMA, and QAM (see below) technologies, users realize much better network throughput, meaning more simultaneous connections with devices.

What about latency? According to Intel, WiFi 6 has ≤ 75% lower latency than WiFi 5. Indeed, WiFi 6 latency intervals have been measured at an astounding 2-6 ms — rates on par with 5G. While WiFi 6's super-low latency has obvious implications for mobile augmented reality/virtual reality (AR/VR), video streaming, and gaming applications, it means WiFi 6 is a viable (and cost-effective) alternative to 5G for Industrial Internet of Things (IIoT) utility.

Alas, while WiFi 6 utilizes more bandwidth (meaning it can transport more data) than WiFi 5, 802.11ax has less range and ability to penetrate impermeable materials when using the 6 GHz band.

MU-MIMO, OFDMA & QAM

At the risk of overwhelming you with acronyms and jargon, we must mention multi-user multiple input multiple output (MU-MIMO), Orthogonal Frequency Division Multiple Access (OFDMA), and Quadrature Amplitude Modulation (QAM). Advances in these technologies are why WiFi 6 is a game-changer for WLANs.

While MU-MIMO was part of the WiFi 5 standard, WiFi 6 introduces simultaneous uplink (UL) and downlink (DL) MU-MIMO for more efficient connectivity. OFDMA (an improvement over sequential OFDMultiplexing) accommodates multiple users simultaneously by dividing a WiFi channel into smaller frequency subcarriers called "resource units" (RUs). Combined, these two technologies facilitate greater data-intensive tasks for both high and low bandwidth (e.g., streaming and IoT) applications or a combination of both simultaneously in dense environments.

WiFi 6's 1024 QAM encodes 25% more data into packets compared to WiFi 5's 256 QAM. Combining 1024 QAM with OFDMA allows 75% less subcarrier spacing compared to OFDM and 256 QAM, enabling the transmission of more data and increasing throughput capacity.

WiFi 6 and IoT

Another big improvement WiFi 6 offers is much-improved battery life performance. Connecting to WiFi networks, especially when a device switches repeatedly between WiFi and cellular networks — or powers on and off — quickly drains a device's battery. As Bluetooth founding father Jim Kardach said, "You have to design things to work efficiently but more importantly, do nothing efficiently."

Previous WiFi standards called for placing end devices in "sleep" mode between AP signals. The device would activate when it had data to transmit. But in a network topology with multiple IoT endpoints (many of which are battery operated or have battery backup), these devices would queue as they waited to transmit, wasting power. WiFi 6 introduces a process called "Target Wake Time" (TWT), optimizing communications between a wireless access point (AP) and an IoT device.

TWT allows an end device to "negotiate" when and how frequently it connects with an AP. Thus the end device can remain dormant until the appointed time of connectivity. So, IoT devices no longer queue (or compete with other end devices) for connectivity with an AP, reducing device power consumption. This innovation also considerably reduces WLAN congestion.

Is WiFi 6 Backward Compatible?

Ostensibly, yes. Like all IEEE 802.11x standards, WiFi 6 is interoperable with previous legacy releases — to a point. The IEEE 802.11ax task group chose to allow only high efficiency WiFi 6 devices to use the 6 GHz (i.e., between 5.925 GHz and 7.125 GHz) band.

This decision makes sense considering the supercharged performance of WiFi 6-enabled devices. But network admins will have headaches locating/disabling/replacing legacy WiFi 3 and WiFi 4 devices clogging up their new autobahn WLAN. Otherwise, these obsolete devices will slow the performance of all network endpoints. Thus, an organization should carefully plan its migration to a WiFi 6 network topology.

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