A short range, high speed protocol, Bluetooth is found in virtually all commodity smartphones. Bluetooth Low Energy (BLE) has the ability to exchange data in one of two states: connected and advertising modes.
Localization can be through signal-strength measurement between base stations which can also provide extra data on the environment. Apple released the iBeacon protocol several years ago which implements a BLE beacon. There is an open source version called AltBeacon supported by Radius Networks.
A short range, high speed protocol, Bluetooth is found in virtually all commodity smartphones. Bluetooth Low Energy (BLE) has the ability to exchange data in one of two states: connected and advertising modes. Localization can be through signal-strength measurement between base stations which can also provide extra data on the environment. Apple released the iBeacon protocol several years ago which implements a BLE beacon. There is an open source version called AltBeacon supported by Radius Networks.
There is a Java library that should do the job.