What is Wi-Fi Direct?

Here is the problem:  I have two devices – lets say my phone and a printer.  On my phone I’ve got an email containing e-tickets to a show I want to see.  All I have to do is print them out from the printer.

Not a problem, right?  My phone and my printer are both connected to the wireless network in my house.  So long as my phone can find my printer (and lets say it can – using UPnP or Bonjour, for instance) and knows how to talk to my printer (this is always a big ‘if’ – but lets assume for the moment it can), then my phone can drive the printer over the wireless network, and my e-tickets can be printed out.  Fine.

Now imagine I’m at a hotel.  I’ve still got my phone, but we’re now talking about the hotel’s printer.  The simple solution might be to join the hotel’s wireless network.  But that might cost money.  Or at the very least be inconvenient.  And imagine I’m not in the hotel at all, I’m in a branch of QwikPrint.  I’m not even sure I would trust their network.  I’m standing in the same room as the printer – I shouldn’t have to jump through hoops.

This is where Wi-Fi Direct comes in.

The way I use wifi-direct might be something like this:  I press a button on the printer, then I go to the wifi-direct setup on my phone.  On it I see the name of the printer (I know this, because there is a label on the printer just above the button I pressed).  I select the name, and we are connected.  Now I can print straight to that printer (with all the provisos about knowing how to drive it we had before).  I haven’t had to join a network.  I’m talking straight to the printer.

How Wi-Fi direct works is simple.  One device decides to act as if it is a wireless router.  The other device connects to it, but only if certain security considerations are met – such as the button on the printer being pressed.  In fact only one of the devices – the one pretending to be a router – needs to know anything about Wi-Fi direct.  The other just thinks it is joining a WPA2 network.  So there is a bit of backwards compatibility built in.  And for the record, this isn’t just a rehashing of the old Ad-hoc WiFi networks we knew (and generally tried to ignore), This is an infrastructure mode, 802.11n connection – just like your standard WiFi and can reach the same potential speeds – up to 250 Mbps.

There are a couple of extra twiddles – while service discovery works using Bonjour or UPnP – just like on a normal WiFi network, WiFi Direct also provides a little bit of extra service discovery majic, which means you can find services without having associated with one another or obtained an IP address.  This means that in my hypothetical print shop, I know that its a printer I’m connecting to.

So, why is this a big deal?

Well, if people support WiFi direct (and the early signs are good), it means we are getting close to the point where home automation might be possible.  Previously, had I decided to buy a washing machine or a thermostat which I wanted to control remotely, I would have a few, quite unsatisfactory choices:

1.  I could connect the device to my home wifi network.  This would be a pain, often involving configuring ip addresses, or at least ensuring the device knew the network’s name.  It would certainly require a more complex display than my thermostat or washing machine currently have
2. My washing machine or thermostat might decide to be their own WiFi router.  In which case I would have to switch network every time I talked to them
3. My washing machine or thermostat might be physically wired to my hub.  Lots more unnecessary wiring running through my house
4. They could have mobile telephony built in, and I would have to connect to them via an external website (security nightmare, not to mention expensive, and probably requires me to pay a subscription)
5. It could all be done via bluetooth.  But that has range issues.  And is slow.

With WiFi direct, the UI on the washing machine or thermostat would be a button.  The UI on the phone would be a drop down list.  And I would have a connection.  In short, the biggest problems of home automation are resolved, and everything else becomes a matter of money and software.

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