by Sam Benzacar, President, Anatech Electronics
Next to cellular service, Wi-Fi is the undisputed champion of wireless services. It’s so well suited for so many applications that in crowded places like airports, convention centers, and stadiums, it can be tough to connect or maintain a connection. Depending on the source you choose to believe, the average home has 10 Wi-Fi-enabled devices, and if it includes gamers and binge-watchers along with the usual smartphones and tablets, it’s possible to max-out a legacy (i.e., 802.11b) access point that has only channels in the 2.4 GHz band at its disposal.
The ability of 802.11n and ac to use 5 GHz channels along with features like MIMO provides massive improvements, but it’s likely even this won’t be enough in the coming years. All of this hasn’t been lost on the Wi-Fi Alliance and Wi-Fi chipset and equipment manufacturers, and help is on the way in the form of 802.11ax, most likely in a few months. When developing the standard, the primary focus was on addressing the issue of congestion rather than simply increasing speed. In fact, 802.11ax is only about 37% faster than 802.11ac but it builds on the “best” of its predecessor and adds a long list of other tweaks, some for the first time in Wi-Fi.
The 802.11n standard that preceded 802.11ac uses both 2.4 GHz and 5 GHz channels, but 802.11ac uses only those at 5 GHz, so a leapfrogging of sorts has been taking place, as 802.11ax also uses both frequencies. It also offers channels up to 160 MHz wide such as 802.11ac, and significantly increases capacity by upping the modulation rate to 1024QAM, a first for W-Fi.
Differences in data rates between the two are self-explanatory, and it’s probably obvious that no one is likely to be experiencing a download rate of 9.6 Gb/s any time soon as Wi-Fi speed can only be as high as its source, typically broadband, and few people have anything close to even 1 Gb/s. That said, when 10 Gb/s becomes available, 802.11ax will be ready. The widely quoted benchmark goal for 802.11ax is to deliver a four-times improvement in throughput and quality of service versus 802.11ac. It aims to deliver this indoors and outdoors and even in dense signal environments. Range is about the same as 802.11ac.
In addition to the above, the major improvements in the new standard come from the following enhancements:
• Orthogonal Frequency Division Multiple Access (OFDMA) modulation: Standards beginning with 802.11g use Orthogonal Frequency-Division Multiplexing (OFDM) and as OFDMA lets multiple devices occupy the same channel, it increases spectral efficiency through better scheduling of devices to avoid “collisions” between them.
• Target Wake Time (TWT): This new feature, at least for Wi-Fi, reduces device power consumption using precise synchronization algorithms so that a device is only fully awake when it needs to communicate with the access point.
• Multi-User MIMO: Wi-Fi has availed itself of MIMO’s benefits for some time. MU-MIMO is a lot more sophisticated, as rather than being able to access a single device at one time, an access point can handle several while modifying the antenna pattern through beamforming to dedicate the most resources to the user devices that needed it most. 802.11ac does this in the downlink path only; 802.11ax adds the uplink path as well.
• Basic Service Set (BSS) coloring: A BSS is the term used to describe a Wi-Fi access point and all the devices that are connected to it. 802.11ax uses a technique called “BSS coloring” to reduce co-channel interference. This should be a benefit in dense signal environments as it makes the reuse of channels more efficient.
These enhancements and others collectively make 802.11ax a huge leap forward for Wi-Fi, and ought to improve overall quality of service everywhere, not just in the most challenging places it’s targeted for. Of course, getting all of the benefits from 802.11ax requires a new access point (router) and an 802.11ax-enabled user device. The first such smartphones are likely to appear when the major players, primarily Samsung and Apple, introduce their next products. TVs and streaming devices could take longer, and public hotspots are likely to be last.
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