Peripherals can list preferred channels with a central device. Previously, only the central device could set channels.
BT 5.2
LE Isochronous Channels
LE Audio
LE power control (LEPC) provides adjustable power that can be requested by peer devices.
BT 5.1
Angle of Arrival (AoA), Angle of Departure (AoD) for tracking
generic attribute (GATT) profile caching makes pairing quicker by retraining requirements.
BT 5
2Mbit/s PHY for LE
Coded PHY: with ECC
More antennas provide greater tracking accuracy, and generic attribute (GATT) profile caching makes pairing quicker by retraining requirements.
BT 4.2:
Designed for the Internet of Things (IoT), BT 4.2 increased the payload size in the Bluetooth packet by 10x, dramatically lowering the overhead to yield 2.5 times more data.
The low-power wireless personal area network (WPAN) version of IPv6 (6LoWPAN) is supported, which enables billions of devices to have a unique IP address.
It also supports beacon privacy, which prevents retail shops from sensing a user's presence (see iBeacon).
BT 4.0: Introduced low-power Bluetooth Low Energy, branded as “Bluetooth Smart.”
BLE
BT 3+HS: Branded as Bluetooth 3.0 + HS (High Speed), it started the connection via Bluetooth but transmitted data over Wi-Fi
BT 2.1: Secure Simple Pairing (SSP) was added to make pairing faster and more secure. Encryption was made mandatory, security was improved, and less power was used.
BT 2.0+EDR (Enhanced Data Rate)
π/4-DQPSK (2Mbit) and 8-DPSK (3Mbit) modulations
Apple: 4 (HDR4) and 8 (HDR8) Mbit/s using π/4-DQPSK modulation on 4 MHz channels with FEC.
Interference handling was improved, and less power was used.
BT 1.2:
BT 1.2 (Basic Data Rate) was the first widely used Bluetooth technology.
Adaptive frequency hopping (AFH) helped avoid interference with Wi-Fi and other technologies in the same frequency.
Pairing speed was improved.
BT 1.1: Improvements to reliability and interoperability; mostly backward compatible but not 100%.