Since its conceptualization by Ericsson in 1994, Bluetooth technology has evolved from the initial Version 1.0 to the latest Version 5.3, with each generation advancing in transmission speed, power efficiency, and application scenarios. Currently governed by the Bluetooth Special Interest Group , Bluetooth is divided into two main branches: Bluetooth Classic and Bluetooth Low Energy (BLE). The former focuses on high-speed data transmission , while the latter supports IoT devices with ultra-low power consumption. In iterative updates, BLE has gradually become mainstream and deeply integrated with Classic Bluetooth.

Comparison of Bluetooth Versions

Technical Features of Key Versions

(1) Classic Bluetooth Era (1.0–3.0)

• 1.1–1.2: Basic voice transmission with weak anti-interference; 1.2 introduced Adaptive Frequency Hopping (AFH) to reduce Wi-Fi interference .

• 2.0/2.1+EDR: Transmission speed increased to 3 Mbps, supporting stereo music (A2DP protocol). Version 2.1 introduced SSP (Secure Simple Pairing) to simplify pairing (no PIN input required) and reduced standby power consumption by 50%.

(2) Transition Period: Bluetooth 3.0+HS

• Achieved 24 Mbps high-speed transmission by invoking 802.11 Wi-Fi modules (requires devices with the "+HS" logo), but high power consumption limited its popularity.

(3) Revolutionary Turning Point: Bluetooth 4.0 (BLE Low Power)

• Dual-mode design: Supported both Classic Bluetooth (BR/EDR) and BLE low-power mode, reducing power consumption to 1/10th of traditional versions.

• IoT boom: Enabled button-cell-powered devices (e.g., bracelets, blood glucose meters) to operate for months or even years.

(4) Leaps in 5.x Series

• 5.0: Extended transmission distance to 300 meters (outdoors), increased broadcast data volume by 8×, and supported indoor positioning.

• 5.2: Introduced core LE Audio features: multi-device audio synchronization (e.g., TWS earbud left-right synchronization) and lossless audio support (24bit/192kHz).

• 5.3: Further optimized power efficiency and anti-interference, reducing 2.4GHz band interference (e.g., from Wi-Fi, microwaves).

Protocol Stack and Functional Layer Characteristics

Bluetooth technology achieves diverse functions through a layered protocol stack:

• Low-level control: HCI (Host Controller Interface) connects hardware and software.

• Data transmission:

• RFCOMM: Emulates serial ports for file transfer (e.g., old mobile phone Bluetooth image sharing).

• L2CAP: Manages data multiplexing and logical channels.

• Application-layer protocols:

• A2DP: Classic Bluetooth audio transmission, supporting only single-device connections.

• LE Audio (5.2+): Supports multi-device synchronized broadcasting (e.g., sharing audio with multiple headsets).

For version selection and compatibility, higher-version Bluetooth devices or chips are recommended. Higher-version devices can connect to lower-version devices but with limited functionality. For example, a Bluetooth 5.0 phone can connect to a Bluetooth 2.1 headset but only supports basic audio.

Through continuous iteration, Bluetooth has evolved from early short-range audio transmission to a core connectivity technology supporting IoT, high-precision positioning, and high-definition audio. When selecting devices, match the version to specific needs (e.g., power consumption, range, audio quality) and consider compatibility and certification marks. In the future, Bluetooth will continue to integrate with Wi-Fi, UWB, and other technologies, driving "Internet of Everything" toward greater intelligence and security.