nRF51822 is an ultra-low power 2.4 GHz wireless System on Chip (SoC) that supports Bluetooth® Low Energy and a range of proprietary 2.4 GHz protocols, such as Gazell.
Fully qualified Bluetooth Low Energy stacks for nRF51822 are implemented in the S100 series of nRF51 Series SoftDevices and can be installed on nRF51822 independent of your own application code.