Wireless Standards · Topic 5 of 5
Future Standards and 802.11ax
Learn what 802.11ax (Wi-Fi 6) adds, including OFDMA, BSS colouring, target wake time and 1024 QAM, and where it appears in RouterOS v7 band names.
- 5 min
- 802.11ax is Wi-Fi 6, and it focuses on efficiency in dense networks.
- It works on 2.4 GHz and 5 GHz, with 6 GHz in some regions.
- OFDMA splits a channel into resource units so that several clients share one transmission.
What it is
802.11ax, also called Wi-Fi 6, is the standard that follows 802.11ac.
Its main aim is not only a higher peak speed. It makes busy networks more efficient, so that many clients share the air better.
The standard is also called HE, for high efficiency, and it works on 2.4 GHz and 5 GHz. Where a region allows it, an extension uses 6 GHz.
How it works
802.11ax keeps the older methods and adds new ones for crowded places.
OFDMA
In earlier standards, one device used the whole channel for each transmission, even for a tiny packet. OFDMA splits the channel into smaller parts called resource units, and different clients use different parts at the same time.
This helps most with many small frames, such as those from phones and sensors. It cuts waiting time and wasted airtime.
MU-MIMO in both directions
802.11ac used MU-MIMO only for the downlink. 802.11ax uses it for the downlink and the uplink.
The access point can now receive from several clients at once, as well as send to several clients at once.
1024 QAM
802.11ax adds 1024 QAM, which carries 10 bits per symbol. 802.11ac stopped at 256 QAM with 8 bits per symbol.
This gives about 25 percent more speed than 256 QAM, but only when the signal is very clean. It helps the clients that are close to the access point.
Other changes
| Feature | What it does |
|---|---|
| BSS colouring | Tags each cell with a colour, so a device can ignore frames from a neighbouring cell that uses the same channel |
| Target wake time | Lets a client and the access point agree when the client wakes, which saves battery |
| Longer symbols and guard intervals | Improve the link in difficult conditions, such as outdoors |
| Wider channels | Channels of 20, 40, 80 and 160 MHz are supported |
Rates
With one stream on an 80 MHz channel, 802.11ax can reach about 600 Mbps. On a 160 MHz channel, it reaches about 1200 Mbps with one stream. The specification allows a total close to 10 Gbps with the maximum number of streams and the widest channel.
Real speeds are lower, and most client devices have only one or two streams.
Where the gain is
The biggest gain is in dense places, such as offices, classrooms and stadiums. A single client near the access point gains less. The standard improves how the network shares time among many clients.
When an exam question asks what 802.11ax improves, think of efficiency and capacity in crowded places, not only peak speed.
Compatibility
802.11ax is backward compatible. Older clients can join an 802.11ax access point and use their own standard. To get the new features, both the client and the access point must support 802.11ax.
An access point that serves many older clients gets less benefit from the new features.
Support in RouterOS
The legacy wireless package covers the standards up to 802.11ac. The wifi driver of RouterOS v7 adds the ax bands.
/interface wifi channel add name=ch-ax band=5ghz-ax frequency=5180 width=20mhz
/interface wifi print5ghz-axand2ghz-axare the band names for the ax standard.- Only hardware with an ax radio can use them.
- The wifi driver is also the base for CAPsMAN v2.
This is one reason that new MikroTik designs use the wifi driver and CAPsMAN v2 together.
What comes next
The next standard after 802.11ax is 802.11be, also called Wi-Fi 7. It continues the same direction with even wider channels and higher density modulation. This guide covers it only as the name of what follows.
A fast access point does not make slow clients faster. Check what the clients support before you pay for new hardware.
What to remember for the exam
Seven facts cover this topic.
- 802.11ax is Wi-Fi 6, and it focuses on efficiency in dense networks.
- It works on 2.4 GHz and 5 GHz, with 6 GHz in some regions.
- OFDMA splits a channel into resource units so that several clients share one transmission.
- MU-MIMO works in both the uplink and the downlink.
- 1024 QAM carries 10 bits per symbol, and it needs a very clean signal.
- BSS colouring reduces interference between neighbouring cells, and target wake time saves client battery.
- On the wifi driver of RouterOS v7, the ax bands are
2ghz-axand5ghz-ax.
Common mistakes
These four errors are common.
Thinking ax is only about speed. Its main gain is efficiency with many clients.
Expecting ax gains from old clients. Both sides must support ax.
Assuming 1024 QAM works at long range. It needs a very clean signal.
Looking for ax settings in the legacy wireless menu. Use the wifi driver menus.
Check yourself
Work through these three questions.
What does OFDMA do?
It splits the channel into resource units, so several clients can send or receive in the same transmission. It reduces waiting time for small frames.
What is the purpose of BSS colouring?
It tags each cell with a colour, so a device can ignore frames from a neighbouring cell on the same channel. This reduces interference.
Which RouterOS driver supports the ax band names?
The wifi driver of RouterOS v7, with names such as
5ghz-ax. The legacy wireless package covers the standards up to 802.11ac.
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