Wifi 40mhz

[Twyla Plack]

Is this a bug, where are bugs reported... I setup an 802.11N channel to 40MHz wide, save and apply setting. I use Acrylic Wifi Home to monitor the channel and its 20MHz wide. I'm using OpenWrt 18.06.0 r7188-b0b5c64c22 with Linksys wrt1900ACS. The original OEM firmware set to 40MHz always showes a 40MHz wide 802.11N channel from Acrylic wifi monitoring.

Not sure if that is correct then lots of router manufacture's firmware is wrong. As I type this, I'm looking at a near-by 40MHz 802.11N signal now. It's using channels 1-8! You'll never get 40MHz channels knocking down the bandwidth but the firmware says 40MHz channel is saved. I'm using Acrylic WiFi to monitor signals. Is this a spec open to interpretation I wonder?

Unless you've got a multi-thousand-dollar or a hundred-pound boat anchor of a spectrum analyzer, what consumer-grade analyzers generally show is what the AP reports as capabilities and not a measure of the true bandwidth in use. They may draw pretty pictures on the screen, but they look in the information broadcast by the AP for numbers and draw a comforting curve from those numbers.

A expensive instrument is not need to measure the bandwidth, cus yes the radios tell you the configuration. I consider this a firmware bug since it says it bandwidth is 40MHz but its still using 20MHz channel.

I just fired up Wifi Analyzer (on my Android tablet) and its show the same thing... a 20MHz channel although the firmware says the setting is 40MHz. I've never seen a wifi router that reports 40MHz setting but is actually outputting 20MHz.

The "noscan" option can be set on the radio to force 40 MHz even if another AP is detected. This is seriously not recommended. It is likely to reduce the performance of your network as well as your neighbors.

You need to set option noscan 1 to enforce the use of 40MHz channels without checking for overlapping adjacent BSSes. Until very recently that option was not exposed in the gui, it was added a few weeks ago to master but is not part of a release iirc.

(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.

This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

Ok, 802.11N is backward compatible with G, A, B etc. I always disable, via the firmware settings, the old G WiFi since I have no radios operating on that technology. So yes as u and I have said that uses spread spectrum technology.

Now the newer 802.11N uses OFMD modulation (same as cell phone technology) on a 20MHZ or 40MHZ channel. OFDM assigns the radio to a subcarrier, aka sub-channel, which is orthogonal to other sub-channel. Essentially the other sub-channels are frequency nullified with the radio operating on a sub-channel. This is how interference is eliminated whether 20MHZ or 40MHZ channel.

If ur talking about interference describe by FCC WiFi is inherently built to handle interferes on co channel or adjacent channel. No reason to not use 40MHz channel on 802.11N. WiFi is design for multiple radios the same channel or adjacent channel.

Incorrect regarding the adjacent channel statement...you assume the users of the adjacent channel are also using N...and for that matter, you assume that the technology in use on the adjacent channel is 802.11n...or even WiFi. You even make that assumption for the channel in question.

The ISM radio bands are portions of the radio spectrum reserved internationally for industrial, scientific, and medical (ISM) purposes, excluding applications in telecommunications. Examples of applications for the use of radio frequency (RF) energy in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so De...

IMHO, today WiFi is mostly used in that range. 802.11N is very popular and prices for these routers are cheap. Other technologies, Bluetooth, microwave oven (1 freq), wireless phone (if still use landline) are in the 2.4GHz band. Your WiFi is not likely to be effected by these other technologies due to the modulation scheme. Other higher power 802.11ABCN routers, if they are in your area are likely to knock you off a channel especially when your reception is weaker that the interference.

Folk, take a look at any OEM WiFi router out there. If u set the bandwidth to 40MHZ, it does it. OpenWRT WiFi routers spectrum is the only 1 not using 40MHz bandwidth, unbelievable u would throw away half your bandwidth. Your interpreting the bandwidth radio operation all wrong.

IMHO, today WiFi is mostly used in that range. 802.11N is very popular and prices for these routers are cheap. Other technologies, Bluetooth, microwave oven (1 freq), wireless phone (if still use landline) are in the 2.4GHz band. Your WiFi is not likely to be effected by these other technologies due to the modulation scheme.

Inaccurate again; and most of your statements are opinion. Last I checked, most people have WiFi, Bluetooth and microwaves, though. I've also seen 2 microwaves, one interferes, one doesn't (different frequencies and/or harmonic leakage). So, no debate here. I'll just agree with @lantis1008 -

Inaccurate again. My device uses 40MHz all the time...when the band isn't congested. I do not have to force 40MHz for this to occur. I simply switch to 40MHz, and when needed (and the band's free), it switches.

I'll be proposing that this thread be closed if we continue into illegal interferance, as the community rules don't support discussion of any other illegal thing. Causing electronic interference is illegal in most countries. We already have a lot of problems with devices because of the fear of malicious actors with 3rd party software...with a lack of knowledge of the Communications Act.

Your comments "illegal interference" is hilariously funny. Wifi 802.11 was made to operate co-channel, i.e. 2 or more radios on the same channel. There are 11 channels operational in the USA, all wifi devices share the bandwidth on multiple channels. I've explained OFDM, when its necessary to download or upload, the radio is assigned a sub-carrier channel (eliminating or null) any interferes aka radios on the same channel. It appears you guys have very little background or foundation is wireless communication.

By the way, its kind of lucky I spent 10 years in network engineering. Average punter on these forums is unlikely to figure out the reason why their Particle is randomly dropping offline and reconnecting.

Also the pricing of such hardware was "Pricing has yet to be defined on the argon at scale, but it will reflect the value created for mesh deployments as opposed to being a module optimized for wifi based deployments. "

So I use my Mac's Wireless Diagnostics WiFi scanner tool to find the best 2.4G and 5G wifi channles to use, then enter my two selected channels into the Wireless Settings page of the Netgear Orbi web console. When I apply the changes, I get the following scary message:

I have no idea what this means or what it is attempting to convey. Does anyone know? Nothing mentioned on the forums and nothing shows up when I google it. It says the same thing no matter what channels I use, as soon as I hit Apply. Does this mean setting specific (least 'chatty') channles may worsen my wifi speed?

hi , the 2.4 gig wifi world is saturated with users and so as to ensure that this doesnt continue to happen the wifi alliance set a rule that forces the 2.4 gig down to 20mhz in areas where the 2.4 gig is congested and to avoid further congestion , its also called neighbor friendly wifi

"Enable 20/40 MHz Coexistence - Disabling this option allows your 2.4GHz wireless to stay in supporting the max speed. Enabling this option may reduce the max speed of your 2.4GHz wireless to the half when there is another wireless network detected in your environment; this is to avoid inteference between wireless networks and to get along with other wireless networks in the environment."

Great. Of course I have some older devices that support only 2.4G, so I guess that means I need to leave this option enabled for them to work, but it will also cripple its max speed. Kinda sucks. That's the whole reason I'm selecting specific channels...to "avoid interference".

Would be nice if we could adjust radio power and turn off unwanted radio altogether used to be able to it got removed last Firmware. Now like a selfish neighbor blasting away radio signals in all directions at full strength and nothing I can do about it anymore more. I have zero use for 2.4GHz but can't adjust power nor turn it off...brilliant design wifi for the future!!

Thanks for the info. With that, and a bit more research, I was able to understand better why the feature exits to drop to a 20MHz wide signal from the legacy 40MHz one, whenever other broadcasters in that range exist.

However, it must be said that the popup message is quite confusingly written. And it also seems to be misplaced--it would make more sense to appeared in the other settings area which actually has the enable/disable option, NOT the channel selection page. Also, this message pops up whenever you "Apply" ANY change on that page, even if it is totally unrelated to the 20/40 frequency thing.