Bluetooth Versions

• Periodic Advertising with Responses (PAwR) - Improve syncing of devices
• Encrypted Advertising Data - Improves security between devices with data encryption
• LE GATT Security Levels Characteristic - Improves security levels between devices
• Advertising Coding Selection - Improves security between devices with improved device identification

• Minor enhancements regarding:
  • LE reliability when communicating with devices far away
  • Encryption key length negotiation
  • LE handling of periodic advertisements
  • Support for faster upgrading of connection speeds

• Bluetooth Low Energy Audio provides support for audio with reduced power consumption
• Bluetooth LE Audio also supports:
  • Isochronous Channels which allow for sharing and broadcasting audio
  • A new LC3 codec made specifically for LE
  • Hearing aids
• LE Power Control automatically adjusts transmitter power levels based on a receiver's signal level

• Bluetooth Mesh which allows for many-to-many communications
• Angle of Arrival (AoA) and Angle of Departure (AoD) allow for tracking the position of devices

• LE 2 Mb/s colocated connection
• LE Long Range
• LE Channel Selection Algorithm
• Slot Availability Mask (SAM) for avoiding nearby LTE transmission frequencies
• Higher Output Power

Starting in version 5, the naming scheme changed to not include the point number in major versions.

• Internet of Things (IoT) related features such as Internet Protocol Support Profile (IPSP) v6
• Low Energy Secure Connection
• Improved privacy with Extended Scanner Filter Policies
• Extended Data Packet Lengths for LE

• Co-existence support for LTE, for reduce interference
• Audio Architecture Updates for HD voice quality
• Fast Data Advertising Interval
• Limited Discovery Time

• An entirely new stack called Bluetooth Low Energy was built to target very low power applications powered by a watch battery.

• High speed data transfers of up to 24 Mb/s using a colocated 802.11 (Wi-Fi) link. Note that HS is an optionally supported feature.
• Enhanced Power Control improves power management and fixes some headset link loss issues
• Enhanced Retransmission Mode (ERTM) for L2CAP supports retransmission and flow control, and a low-latency Streaming Mode (SM) support neither.
• Unicast Connectionless Data for small amounts of service data without an L2CAP channel

• Improved pairing security and experience with Secure Simple Pairing (SSP).

In previous versions, encryption wasn't required and could be turned off, and usage of expired keys could be easily attacked.

Starting in 2.1:

• Encryption is required for most connection types
• Encryption keys must be refreshed

• Enhanced Data Rate (EDR) allowing for data transfer up to 2.1 Mb/s. Note that EDR is an optionally supported feature.

• Faster connection and discovery
• Adaptive frequency-hopping to avoid interference on crowded frequencies
• Retransmission of corrupt packets with Extended Synchronous Connections (eSCO)
• Faster transmissions speeds of up to 721 Kb/s
• Host Controller Interface (HCI) three-wire UART
• Flow Control and Retransmission Modes for L2CAP

• Unencrypted channels
• Recieved Signal Strength Indicator (RSSI)
• Various interoperability problems from 1.0b were fixed

• The initial release of Bluetooth