## System

- Use beacons mounted on stationary objects within a room to allow user
  supplied devices to triangulate their rough position inside the room
- The users may share their location via various means.
  - XMPP
    - complex
    - relies on external infrastructure eventually
    - robust against network topology traversals (NAT/Firewall)
  - Multicast
    - simple
    - not robust when traversing NATs
- Useful for a conference hall or the like, where an area is large
  enough to prevent finding ones way or friends easily.

testing guest captcha

## Hardware

### SOCs

- [Nordic](http://www.mouser.com/ProductDetail/Nordic-Semiconductor/nRF51822-QFAB-R7/?qs=sGAEpiMZZMvQqVCO1QUke9rOCiF3q8UDR59ukwBL9d8%3d)
- [TI](http://www.mouser.com/ProductDetail/Texas-Instruments/CC2540F128RHAR/?qs=sGAEpiMZZMuReUCzg6bfTFMX9eNsg5flb%2fyNLpDtSPE%3d)

### Front End/BT modules

- just as expensive as SOCs

## Software

### Phone App

#### Android

#### iThing

### Firmware

- bit-bang BTLE library
  [code](https://dmitry.gr/index.php?r=05.Projects&proj=11.%20Bluetooth%20LE%20fakery)
  for reference

#### Beacon

- Similar use cases
  - Beacon tagging - tags beacon to allow device to find the tagged item
    - [iBeacon](http://en.wikipedia.org/wiki/IBeacon) - proprietary
      implementation
- Use [Proximity
  Sensing](http://en.wikipedia.org/wiki/Bluetooth_low_energy#Proximity_sensing)
  Profile (PXP/FMP) to let user devices know where and roughly how far
  they are from the beacons.