I developed a wireless communication device by leveraging the support of 5/10 MHz narrow bandwidth in the past 802.11n Wi-Fi modules.
We developed a wireless communication device by converting frequencies to a frequency band other than the 2.4 GHz Wi-Fi bandwidth.
I want to upgrade this system so that it can now have a higher speed.
So I want to use 802.11ax or higher Wi-Fi modules or chipsets, but it's hard to find a case where the feature is open to use 5/10MHz bandwidth on 802.11ax. Does anyone know of any of these examples?
I have confirmed that the device from TobuFi and Vizmonet in 8Devices is stated in the specification that 5/10MHz is available, but I have not found it except in this case.
Is there any idea?
Neither IEEE 802.11ax (Wi-Fi 6/6E) nor IEEE 802.11be (Wi-Fi 7) supports channel widths of 5 MHz or 10 MHz.
These standards define OFDM/OFDMA-based PHY layers with supported channel bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz (and 80+80 MHz non-contiguous), and for 802.11be additionally 320 MHz (primarily in the 6 GHz band). The minimum operational channel width is 20 MHz.
Narrower widths like 5 MHz or 10 MHz are found in other 802.11 amendments, such as:
- 802.11ah (Wi-Fi HaLow, sub-1 GHz for IoT),
- 802.11y (3.65 GHz band in the US, allowing 5/10/20 MHz).
Of course, as a developer of "a wireless communication device" you will fully appreciate that "speed" (aka bitrate) is inversely proportional to the bandwidth used.
This means if you want to ~double the bitrate you previously achieved, then using 20MHz channels will do it for you, with many 5GHz-band non-overlapping channels available for use.
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I've only seen 5GHz and 10GHz bandwidths supported on older Atheros chipsets (e.g. ath9k).
Also potentially relevant - some jurisdictions place limits on transmit EIRP per MHz bandwidth.
For instance in the United Kingdom, part of the 5GHz band is limited to "Maximum mean e.i.r.p. of 1W. Maximum mean e.i.r.p. density of 50mW/MHz in any 1 MHz band".
In this case, 1W EIRP on a 20MHz bandwidth is also at the 50mW/MHz limit, so the overall max tx power would have to be reduced 500 mW for 10 MHz of 250 mW for 5 MHz wide bands.
This information isn't encoded in the Linux regulatory database ("wireless-regdb"), so depending on your market, you might need to take additional (arduous!) steps to ensure regulatory compliance too.
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I think you intended your reply for @thkim but yes, I am pretty sure what you are saying is correct.
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You're right.
I also developed a wireless communication device using the old Atheros chipset (ath9k driver).
At the time of its development, att9k was not difficult to implement 5/10 MHz bandwidth.
However, implementing 5/10 MHz bandwidth on the 802.11ax chipset (ath11k?) does not seem easy.
However, based on 8devices' ToBuFi or Vizmonet's device specifications, I was wondering that it would not seem completely impossible to support 5/10 MHz bandwidth and implement 5/10 MHz bandwidth.
Of course, I understand that the 802.11ax's 5/10 MHz bandwidth is not standard.
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I understand that the standard does not support 5/10 MHz.
However, I was wondering if I could implement 5/10MHz on the 802.11ax chipset like the old at9k chipset. (Of course this is not standard.)
To be clear, it is more than "not supported", it is also not permitted under any regulatory domain.
To be even more clear, regardless of whether you developed something or not, 5 and 10MHz operation on 2.4GHz bands is also not permitted anywhere as far as I can ascertain.
If you are in the US(FCC) domain then if you modified the firmware/supporting-hardware of a particular chipset to run in the 3.65–3.7 GHz band (aka 802.11y) then this would be ok providing you also obtained FCC approval for the modification.
The current, up to date standard for this type of functionality is 802.11ah (aka HaLow). This can use 1, 2, 4, 6 and 16 MHz bandwidths, but is limited to below 1GHz spectrum.
Best support for this is currently US domain and operates in the 902–928MHz band.
Canada echoes this, but other domains have many limitations and operate on other frequency bands.
You sound confused about what your requirement actually is.
Higher speed would result from using the readily available 20MHz bandwidth without having to modify anything.
I suggest you do some more in depth research on the subject.
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I already know the things you said.
However, since the device I developed that converts frequencies is regulated by TV White Space, there is no problem with 5/10 MHz bandwidth (actually allowed bandwidth is 6 MHz, 12 MHz), but rather, 20 MHz bandwidth is generally not available.
The 802.11n chipset supported 5/10 MHz bandwidth (unofficially)
I know I just need to use 20MHz bandwidth for faster speeds, but I can't do that in the TV White Space regulatory domain.
That's why I think the only solution for modulation is to upgrade from 64QAM to 1024QAM, and for that to happen, I needed to make sure that the 802.11ax module could operate at 5/10MHz bandwidth.
That's good, but it would have saved time and reduced noise on this forum if you had been up front with what you have now stated!
I do apologise for my frustration and possible sarcasm, but both 802.11ah and 802.11af are very interesting subjects, with 802.11ah being potentially very relevant to OpenWrt.
802.11af, not so much as there is no type approved hardware available for OpenWrt developers to get their hands on.
Presumably you are well aware of the above mentioned IEEE 802.11af standards?
This is the requirement for operating in "TV whitespace" in all regulatory domains as far as I can see.
Of course your already developed device will have its mandatory GPS receiver and the associated Geolocation-Database/ Cognitive-Radio integration for the areas you intend to operate, as you will have obtained your local type approval. /s
For example:
- Devices operated in the US must have mandatory certification under FCC reg. 47 CFR Part 15 Subpart H and have a respective FCC ID.
- Devices operated in the EU must have mandatory certification under ETSI EN 301 598 and have a respective CE mark.
You may well find it more productive, at least on this forum, to close this thread and open a new one, entitled something like "Using Wi Fi HaLow (802.11ah) with OpenWrt".
As for TVWS, if you hack existing chipset code you can quite possibly find yourself in a difficult situation if you do not go through the proper process.
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