What are the three major Bluetooth standards?

In the intelligent era of the Internet of Everything, Bluetooth technology has become a core link for connecting devices and building ecosystems. From wireless headphones to smart homes, from medical monitoring to the Industrial Internet of Things, Bluetooth, with its low power consumption, high compatibility, and flexible deployment capabilities, has permeated every aspect of human life. However, Bluetooth is not a single technology, but rather consists of three major systems: Classic Bluetooth, Bluetooth Low Energy (BLE), and Dual-Mode Bluetooth. This division is not arbitrary, but rather based on the dual dimensions of functional modes (such as data transmission requirements and power consumption characteristics) and protocol standards (such as protocol stack design and communication mechanisms) to precisely adapt the technical requirements of different scenarios.

Classic Bluetooth

Classic Bluetooth (covering Bluetooth 1.0 to 3.0+EDR) is the starting point of Bluetooth technology. Its core design goal is to achieve high-quality audio transmission and high-speed data exchange. This standard division is mainly reflected in the deep integration of functional modes and protocol standards:

Functional Mode: Real-time and High Bandwidth

Classic Bluetooth is designed for scenarios that require continuous and stable data flow, such as audio transmission (such as wireless headphones) and file sharing (such as syncing data between a phone and a computer). Its functional mode emphasizes low latency and interference immunity, enabling real-time audio transmission through synchronous connection-oriented (SCO) links and supporting non-real-time data exchange through asynchronous connectionless (ACL) links.

Protocol Standards: Complete Protocol Stack Architecture

Classic Bluetooth utilizes a complete seven-layer protocol stack, including core modules such as the Physical Layer (PHY), Link Management Layer (LMP), Logical Link Control Layer (L2CAP), and Service Discovery Layer (SDP). This architecture supports complex communication mechanisms, such as the master-slave model (1 master + 7 slaves) and the piconet structure, but also results in high hardware resource utilization and power consumption.

Division Logic: Classic Bluetooth's functional mode (real-time and high bandwidth) necessitates the support of a complete protocol stack, and the complexity of the protocol standard further reinforces its irreplaceable nature in specific scenarios.

 

Bluetooth Low Energy (BLE)

Bluetooth Low Energy (introduced in Bluetooth 4.0) is a revolutionary breakthrough in the evolution of Bluetooth technology, designed to provide an ultra-low-power, long-lasting communication solution for IoT devices. The criteria for this standard's division are also based on the coordinated optimization of functional modes and protocol standards:

Functional Mode: Low Power Consumption and Flexible Topology

BLE's functional mode focuses on "on-demand communication." Through a connectionless broadcast mode and low duty cycle technology, it reduces device idle power consumption to microwatts. For example, a smart bracelet synchronizes data with a phone in standby mode solely through broadcast mode, reducing power consumption by over 90% compared to Classic Bluetooth. Furthermore, BLE supports mesh network topologies, enabling multi-hop communication and extending coverage to kilometers, making it suitable for large-scale deployment scenarios such as smart lighting and industrial sensors.

Protocol Standard: Simplified and Modular Design

The BLE protocol stack utilizes a separate host-controller architecture (HCI), retaining only the physical layer (PHY), link layer (LL), and host layer (such as GATT and ATT protocols). Its core protocol, GATT (Generic Attribute Profile), uses an attribute-value pair model to simplify data transmission and reduce hardware resource usage. For example, BLE devices do not need to support the full Service Discovery Protocol (SDP), instead enabling fast pairing through predefined attribute UUIDs. Classification Logic: BLE's functional modes (low power consumption and flexible topology) require an extremely simplified protocol standard, while its modular design further unleashes its potential in IoT scenarios.

 

Dual-mode Bluetooth

Dual-mode Bluetooth (supported since Bluetooth 4.0) integrates the Classic Bluetooth and BLE protocol stacks, achieving "dual-use on one chip" functionality. The classification reflects the dynamic balance between functional modes and protocol standards:

Functional Mode: Compatibility and Scenario Coverage

Dual-mode Bluetooth supports both the high-bandwidth transmission of Classic Bluetooth (such as audio streaming) and the low-power communication of BLE (such as sensor data acquisition). For example, a smartphone uses the SCO link of Classic Bluetooth when playing music, but switches to the GATT service of BLE when connecting to a smartwatch. This compatibility of functional modes makes it a key node connecting traditional devices with the IoT ecosystem.

Protocol Standard: Coexistence and Dynamic Switching

Dual-mode chips share the RF module at the physical layer and support dynamic protocol switching at the link layer. The protocol stack decouples Classic Bluetooth from BLE through the Hardware Abstraction Layer (HAL), ensuring interoperability at the physical, link, and host layers. For example, dual-mode headphones can automatically adjust their power mode based on usage scenarios: using the Classic Bluetooth protocol for audio transmission and switching to BLE broadcast mode in standby mode.

The logic behind this division: Dual-mode Bluetooth's functional modes (compatibility and scenario coverage) require protocol standards to support dynamic switching. This coexistence of protocol standards has made it a market mainstream feature (currently, over 90% of Bluetooth devices use dual-mode chips).

 

From Classic Bluetooth laying the foundation for audio transmission, to Bluetooth Low Energy ushering in the IoT era, to dual-mode Bluetooth serving as the bridge connecting the two, the evolution of the Bluetooth standard has always been guided by user needs and industry trends.