Multiple smartphones and raspberries pi wireless connections

I’m working on an installation project where the visitors walk across a video installation (many videoprojectors in many rooms) with a smartphone. I’m looking for a way to trigger different videoprojections, on the walls, from the phone. ie:

  • a videoprojection start when the visitor push a button on the phone
  • a videoprojection start at the end of another video playback on the phone
  • a videoprojection start according to the phone sensors (gps, accelerometers)
    And I need the smartphones to receive messages when the videoprojections are finished.

My first thought is to have one rapsberry (or similar device) plugged to each videoprojector, to run an OF app in each raspberry, another one in each smartphone, and to establish wireless connections between the smartphones and the raspberries to make the apps communicate.
Does anyone can provide me some advices or directions ?

  • The building is an old, empty block of flats
  • There is no network available in the building
  • The raspberries (and the videoprojectors) will be dispatched among many rooms and many floors (5 or 6 rooms, in 3 or 4 different flats, in 2 or 3 different floors)

I think because of the distance (and the number of devices ?), it isn’t possible for each smartphone to be connected all the time to each raspberry, peer to peer, by wifi or bluetooth.

  • Is it possible for a smartphone to automaticaly connect to a rasperry, by wifi or bluetooth, when it enter the rasperry range, without user interaction needed ?
  • And what if two smartphones are in the same rasperry range ? Can a rasperry be connected to multiples smartphones at the same time ?
  • And what if a smartphone is in the range of multiples rasperry ?
  • Do I need to create a central network, where each device can connect to a central server, so the smartphones can inform all the raspberries about their state within the visitour tour ? And so that the raspberries can inform when they stop playing a video ?
  • How can I create a central wireless network ?
    That is the list of all my questions.

Thank you for any help !