Powerline Ethernet adapters & UPS?

Levi Pearson levipearson at gmail.com
Fri Mar 15 15:31:51 MDT 2013


On Fri, Mar 15, 2013 at 12:52 AM, Dan Egli <ddavidegli at gmail.com> wrote:
> *That would be an interesting project, I'll admit. Probably be more
> expensive than a regular AP though. I admit I haven't looked at prices of
> USB WiFi dongles lately, but last I looked (a few years ago) the dongle was
> around $90-100 or so. Add that to around $100-120 for the other components
> (Pi board, SD card, powered USB hub, 4-port gigabit hub) and you're around
> $190-220 where as a good WiFi AP would only be around $160-180 at a guess.
> Considering I'll be stringing this whole thing together on a portion of a
> Shoestring budget, $30 is something I could use elsewhere. Still, a fun
> concept, I'll admit. *

Well, you don't have to use a Pi, you could use any Linux-capable
computer you happen to have.  The WiFi dongles vary greatly in price;
some are really cheap, others are really expensive.

>
> * *
>
> *Question though. Last I tried, you could only connect WiFi adapters to
> other adapters on a 1:1 basis. You couldn't have one computer with one WiFi
> adapter (dongle or PCI card, and yes it's been that long since I looked at
> WiFi. PCIe hadn't been released yet) serving multiple computers wirelessly.
> To serve three wireless clients, you needed three wireless adapters or an
> Access Point. Now if this has changed then I'm all ears. In theory, at
> least in my mind, what I could end up doing in that case is having the
> single AP I turn into a bridge and have it served by a USB dongle on the
> machine that serves the PXE clients, and could even have my TV get access
> to Netflix and what not using WiFi. I like this, if it's going to be very
> easy. If you know of a particular USB dongle that could serve this purpose
> I'm all ears!*

You have always been able to connect multiple adapters directly
together via Ad-Hoc/Infrastructure mode.  But you don't have a bridge
to a wired network in that case unless one of the devices is connected
to both and can do bridging, at which point it might as well be
configured as an access point instead.

See http://linuxwireless.org/en/users/Drivers for a list of which WiFi
chipsets have Linux drivers that support modes other than Station.
Some recent chipsets can do Station, Ad-Hoc/Infrastucture, Master/AP,
Monitor, or Mesh modes.  Some can even be configured to multiple modes
at once, though you lose bandwidth when you run multiple interfaces
over the same antenna.

I have some Pandaboards configured to act as Stations and APs
simultaneously.  They're a bit more expensive than Raspberry Pis, but
definitely more powerful and with a lot more functionality built-in.
Not quite as much community support, though.

       --Levi


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