Re: WIFI Direct

[Dan Williams <dcbw redhat com>]

On Wed, 2009-11-18 at 11:34 -0800, Dan Williams wrote:
> On Wed, 2009-11-18 at 10:04 +0000, Jue Yang wrote:
> > Hi,
> >  
> > I am going to develop WIFI Direct on NM 0.7.0, but still a fresh to
> > NM.
> > I wonder if someone can give me some suggestions or whether NM group
> > may put WIFI Direct on schedule?
> 
> We talked about it (well, me and many of the other people involved in
> Linux wireless) at the Wireless Summit in September.  We'll first need
> support for it in wpa_supplicant before NetworkManager can use it.
> Next, we'll need to be able to identify WiFi Direct APs (which we can do
> based on beacon IEs or IIRC the standard-format SSID of the peer) and
> show them to the user in the menu or otherwise.
> 
> Basically, NM should be able (with wpa_supplicant) to set up the
> connection to the WiFi Direct peer, and then outside NM, the service
> discovery protocols can take over and the user can do whatever they want
> (download pictures from the camera, upload them to the photo frame,
> etc).
> 
> But the majority of the work will be in wpa_supplicant and the kernel
> drivers I expect.  Note that for most of the current drivers, connecting
> to a WiFi Direct peer will probably terminate your current connection,
> because the WiFi Direct peer will likely be on a different channel than
> your access point.  This is the same situation with Bluetooth 3 and so
> we should probably handle it the same way.
> 
> Now if we want NM to be the wifi peer that say a camera can connect to,
> we'll still need support for this in the kernel drivers and
> wpa_supplicant before we can do this.  Then I'd think it would be a
> variation on the "create new wifi network" that NM already supports, but
> with some additional capabilities.
> 
> I think to start with, you should write a few paragraphs about some
> target use-cases and how the user would conenct.  Something like:
> 
> "Mary wants to send pictures to her picture frame.  Both her laptop
> (running NetworkManager) and her picture frame support WiFi Direct.
> Mary opens the applet menu and sees here picture frame in the list of
> wifi networks.  She clicks on the picture frame, waits a few seconds for
> the connection to be set up, and then her photo manager alerts her that
> a  new photo frame is available, and would she like to send her newest
> pictures to it?"

The above paragraph isn't quite accurate because it doesn't actually
reflect how WiFi Direct works, of course, but you get the idea :)  Given
that the spec isn't out yet we won't know exactly what the quirks are
for a month or two, but we should have enough information to get most of
the interaction down correctly.

It'll depend on the capabilities of the peer too; for example can the
peer hop to another channel so that we don't have to break the current
AP association just to upload pictures to the picture frame?

If your AP is on 5GHz but your picture frame is on 2.4GHz and you have
dual radios in your card (which will probably be more the case in the
future) then you may not need to break the association.

It can get complicated :)

Dan

> We want to get some detailed ideas of how the user interaction will
> proceed before we start doing most of the NetworkManager work.  That way
> we can try to anticipate some of the problems that users might encounter
> when using it.
> 
> Are there other use-cases you can think of?  We should pick 3 or 4
> use-cases, write them up, and then make sure that the solution we pick
> for NetworkManager enables all of them.
> 
> Dan
> 
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