Bluetooth Low Energy (BLE), or Bluetooth Smart as it is also called, was originally developed by Nokia under the name Wibree and was originally released in 2006. It was integrated into the Bluetooth 4.0 specification and released in 2010.
Bluetooth is a wireless connection technology that operates in the 2,400-2,483.5 MHz range of the 2.4 GHz frequency band. There are 79 data channels it can choose for transmitting packets. BLE limits the data channels to 40.
BLE is targeted at mobile and embedded devices that require lower power consumption. Unlike Bluetooth, BLE is designed for devices that exchange small amounts of data periodically, as opposed to regular Bluetooth that was designed for continuous data streams. Most importantly, BLE has a sleep mode that it uses to conserve power.
Qt has support for BLE in the Qt Connectivity module alongside...
