Bluetooth Low Energy (BLE)

BLE is the default way for a battery-powered device to talk to a smartphone, for setup, configuration, data sync and control. It is maintained by the Bluetooth Special Interest Group (SIG) and is distinct from Classic Bluetooth, which has traditionally carried audio. Because the radio can stay off most of the time, small-battery devices can run for long periods.

Real-world range and throughput depend heavily on antenna design, enclosure, transmit power and the phone on the other end. BLE is often used only for commissioning, to hand the device credentials for Wi-Fi or Thread.

Where it bites: phone operating systems differ in how they handle background connections and permissions, so app behavior varies; and a product that uses Bluetooth technology and branding must complete Bluetooth SIG qualification and listing, in addition to regulatory radio approval.