Don’t 802.11ax, channel width and OFDMA mean much to you? That is not your fault, because the Wi-Fi world likes to use very complex concepts. If you want to dig a little deeper than Wi-Fi 1 to 7, this article will give you a little more guidance.
Toon van Daele
First, let’s clear up a small but persistent misconception: Wi-Fi doesn’t stand for wireless fidelity†It’s just a fun-sounding term with a nod to that popular audio term hi-fi (high fidelity†Technically speaking, this is the 802.11 protocol (a protocol is a specific way of communicating digitally), which has been established as a standard for wireless Internet communication based on radio waves (see also the article ‘Wifi? Lifi!’) in this issue.
The first real commercial application was the 802.11b standard from 1999. In the meantime, several versions of this protocol standard have been reviewed, eagerly picking from the alphabet: essentially from b, a, g and n to ac, ax and be. It will come as little surprise that each new version came with its own additions and optimizations. Fortunately for the consumer, all versions so far appear to be backwards compatible. In other words: if you have a router that works with 802.11ac, for example, your laptop with an 802.11ax WiFi adapter will normally communicate with it without any problems (but the possibilities of that router may be more limited).
COUNTER
Admittedly, these protocol names do not sound very attractive and the Wi-Fi Alliance, the body that deals with Wi-Fi standards, also recognized that. He therefore introduced clearer terminology in 2019. We briefly introduce them here, each time with the protocol name, the year of introduction, the radio frequency(s) and the theoretically feasible throughput (Mbps stands for megabits per second, Gbps for gigabits per second):
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Wifi is taking off, from 1 to 6 (and above) (source: FS Community) • Wi-Fi 1: 802.11b, 1999, 2.4GHz, 11Mbps |
Unfortunately, the practice turns out to be a little less straightforward, because in the meantime all the standards Wi-Fi 6E (extended from 2020) and Wi-Fi 6 R2 (release 2 in 2022) a fact.
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| Wi-Fi 6E now supports the 6GHz band in addition to the 2.4 and 5GHz bands |
WI-FI 6E AND 6 R2
The most important innovation in Wi-Fi 6E is that it can also address the 6Hz frequency band and recently a part of that band was also made available in the Netherlands. Because hardly any devices already use this band, higher speeds can be achieved. This can be useful for devices that require a lot of bandwidth, such as 8K televisions and virtual reality sets. You can then use the other bands for your other network devices, such as smartphones and smart TVs on the 5GHz band and IoT devices on the 2.4GHz band. Such a setup is also somewhat safer, because the latter can then be more easily placed in a separate network. The optimizations of Wi-Fi 6 R2 are less easy to explain. Keep in mind that this again allows slightly smoother connections with shorter latency times, i.e. fewer delays. This can be useful for video conferencing, for example, and when uploading large files. Furthermore, Wi-Fi 6 R2 is also more energy efficient, which can be especially useful with devices that run on a battery.
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| Wi-Fi 6 routers have become quite affordable (here: the D-Link R15) |
PURCHASE
However, before you run to the store for, for example, a router with the latest standard, you should realize that such a device can be much more expensive than one from a previous generation. For example, Wi-Fi 6 routers are currently becoming affordable, such as the D-Link R15 Eagle Pro AI AX1500 of approximately € 70, – but you still pay considerably more for 6E routers. Moreover, it is not the case that you can automatically use all the advantages, because your other WiFi devices may not yet be able to handle them. For example, a throughput of almost 10 Gbps with Wi-Fi 6 seems attractive, but in practice you will probably hardly get 1 Gbps (assuming your internet connection and subscription allow that speed at all). Finally, no matter how easy the Wi-Fi Alliance wants to make it users with the new terminology, some technical baggage is unfortunately unavoidable if you want to properly estimate what techniques such as TWT or SMPS from Wi-Fi 6 R2 can benefit you. Read further on in any case for some background behind those often used WiFi terms.
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| The channel width is often set to automatic, but you can adjust it manually if you want |
CHANNEL WIDTH
As mentioned, a WiFi signal operates within a certain frequency band. Such a signal occupies only a small segment of that band, a so-called channel (channel) with a specific width, which is usually expressed in MHz. By default, such a channel is 20 MHz wide. For example, the 2.4 GHz band offers three non-overlapping channels (channels 1, 6 and 11), the 5 GHz band basically has 25 available and the 6 GHz band currently has about 59. Depending on the used protocol, you can bundle multiple channels in your router or access point to reach widths up to 40 MHz (2.4 GHz band), or even up to 80 and 160 MHz (5 and 6 GHz band).
Be aware that wider channels take up more space in the spectrum and can therefore more easily lead to interference, such as with neighboring networks. If you do indeed suffer from dropping signals in a busy WiFi environment, take a look at the effect of setting the channel width lower (for interference, see the article ‘Doctor Wifi’, under ‘Channel overlap’). It cannot be ruled out that some of your WiFi devices will not even connect if the channel width is too large. In this context, the term OFDMA is also important, a technique that was introduced with Wi-Fi 6. This term stands for orthogonal frequency division multiple access, but what you especially want to remember here is that this allows your router to split a channel to serve multiple users simultaneously. This is especially beneficial for applications that do not require a lot of bandwidth.
TIRE STEERING
Most modern routers and access points support multiple bands, such as 2.4 and 5 GHz (Wi-Fi 4 and 6) and even the 6 GHz band (Wi-Fi 6E). Routers that can broadcast across multiple bands at the same time are then called dual-band or tri-band routers. However, it is also possible that a tri-band router runs one signal over the 2.4 GHz band and offers two separate signals, each over a 5 GHz band. This can be useful if you want to control a large number of 5GHz devices at the same time.
Normally, wireless devices that are capable of connecting on different bands determine which Wi-Fi network they connect to. In practice, unfortunately, they do not always make the optimal choice, resulting in unreliable connections. A router, access point, or repeater that tire steering supports, then offers solace. Such a device recognizes for each network device with which WiFi network it works best. For example, the 2.4GHz network usually has a slightly longer range, because of the lower frequencies that pass through obstacles such as walls more easily, and the 5GHz network is better suited for shorter distance devices that require more bandwidth. So check whether the router you have in mind is tire steering offers.
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| DFS channels are ‘off limits’ unless your router can handle DFS |
DFS
For example, if you look closely at the image with the various channels and channel widths, you will see that the 5GHz band basically has 25 non-overlapping channels with a channel width of 20 MHz available (12 of 40 MHz; 6 of 80 MHz and 2 of 160MHz). In principle, yes, because unfortunately you cannot use all of them without further ado. For example, the highest channels are located in the so-called UNII-3 band and are not allowed in the Netherlands and Belgium. You can use the lowest channels (in the UNII-1 band). The majority of the other channels are the so-called DFS channels (Dynamic Frequency Selection) and are also used for radar, such as for satellite communications, weather stations and military purposes. Because such signals easily reach up to 100 kilometers and further, there is a real risk that your router can also pick up those radar signals. To avoid interfering with the radar signals, your router will not use those either unless it supports DFS.
This means that the device automatically switches to another channel as soon as it detects radar signals. If the 5GHz band in your area is already busy with neighboring networks, then it is a good idea to buy a router with DFS support, since it has more channels at its disposal. A possible disadvantage is that frequently switching to another free DFS channel can cause some delay. Practice will therefore show whether it is best to enable or disable the DFS function.