Specific questions about USB/WiFi interference

Started 2 months ago | Discussions thread
Aristide Rutilant Forum Member • Posts: 84
Re: Specific questions about USB/WiFi interference

You look to be very confused on how these things works.

USB is a physical interface used to easily plug and use devices into your computer, including wifi dongles. USB is backward compatible, so if you plug an USB 2 device in an USB 3 connector, provided that the plug and connector are the same type, and that your computer has the right driver, it will work. The reverse should also be possible although it may depend on the device. USB 3 features, which include much faster transfer speeds won't be used. It can be an issue with an USB 2 dongle if the said dongle proudly pretends it's able to provide more than maximum 480 Mbits/s transfer speed offered by USB 2. In practice, it shouldn't be a problem as advertised Wifi speeds are about 10 to 20 times higher than actual, real life ones and that modern, fast Wifi dongles should be using modern, fast USB 3 interfaces.

Wifi is a standard to do networking on a particular physical support that's known as air, instead of a copper cable or a fiber. There's now about 6 major revisions, and it almost always provided a choice between two frequency ranges, the 2.4 GHz and the 5 Ghz. 2,4 GHz is the most used one, features a better range at the expense of much much less available spectrum and slower speeds. 5 GHz is the reverse, it's still rarely used, provides better speeds and has more spectrum available to it but the range is shorter. In practice, the range you'll use will depend on what's provided by your access point / router and then it'll be negociated between this and your computer in an attempt to give you the best possible stability.

I mentionned interfaces for a good reason, in computing, interfaces are also here to provide some kind of abstraction for whatever is using them. So when you use wifi, you have in effect at least two physical interfaces. One between the air and you network card, that's the antenna, and one between the network card and the rest of your computer, that can be USB. Usually, USB ports are then routed to a controller chipset that interfaces itself with PCI express before speaking to the other parts of your computer. A lot of network cards are also directly interfaced through PCIe to computers.

Unless the Wifi card is physically broken or damaged, there will be no interference between your USB ports and your wifi network.

However, there can be interferences between wifi networks, especially in the 2,4 GHz range. Not only it's the most used one, but the limited amount of spectrum make it so that there can be at most 3 wifi networks in the same space before you'll encounter interferences and those networks need to be on 'opposite' channels (that is 1, 6 and 12). Also a lot of other devices also use this range, such as bluetooth or various cordless / wireless appliances.

There can also be interferences between USB devices, sort of. If the manufacturer hasn't built the controller and ports to spec, if an USB 2 device is plugged in an USB 3 port or vice-versa, or if too many USB devices are plugged in a computer and try to draw too much power from it, then malfunction can happen too.

In your case: the NUC should already have a Wifi network card integrated. Plug whatever you want in its USB ports. If your wifi turns out to be crappy try the following by order of effectiveness:

  • Use a wired network
  • Better place your AP, it should be in a high, central position in your house
  • Try to force the use of a given frequency (but be warned that 5 GHz won't help you if the devices are 50 m appart with thick walls).
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