We assume the mobile device 808 and the beacon device 813 have been previously paired during system setup. A native application running on beacon device 813 keeps scanning for wireless-enabled devices periodically, until an identifier for a mobile device 808 shows up. Then, beacon device 813 periodically sends a wireless message to wake up data collection module 810 on mobile device 808 to gather sensor data.

FIG. 8C illustrates a variation of the system in FIG. 8B, wherein beacon device 813 is replaced with an adaptive beacon device 814. During operation, a native application running on adaptive beacon device 814 keeps scanning for known wireless-enabled devices, until a known device is discovered. Then, adaptive beacon device 814 triggers sensor data collection by sending messages to mobile device 808 at variable intervals, based on feedback previously received from learner 805, which analyzes sensor data from remote database 812. It requests more data when necessary (for example, when we have less information about the user and want to know more) and less when data is not needed (for example, when the user is asleep and is not generating useful data).