Sign in Subscribe

bluetooth low energy architecture in iot

Last updated on 

Bluetooth Low Energy (BLE), also known as Bluetooth Smart, is a wireless communication technology designed for short-range communication and is especially popular in IoT (Internet of Things) applications due to its energy efficiency. Let's dive into the technical architecture of Bluetooth Low Energy in IoT:

1. Physical Layer (PHY):

The BLE physical layer is responsible for transmitting and receiving radio signals. It operates in the 2.4 GHz ISM (Industrial, Scientific, and Medical) band. This band is divided into 40 channels, each with a bandwidth of 2 MHz.

  • Frequency Hopping: BLE uses frequency hopping spread spectrum (FHSS) to avoid interference and fading. This means that the signal hops between different channels rapidly, providing resilience against interference.

The Link Layer handles the connection establishment, data transfer, and error checking between devices.

  • Advertising and Scanning: BLE devices can operate in two modes: advertising and scanning. Advertising devices broadcast packets at regular intervals, while scanning devices listen for these packets. This is how devices discover and connect to each other.
  • Connection Establishment: After a scanning device detects an advertising device, a connection can be established. The Link Layer manages the connection parameters like connection interval, slave latency, and supervision timeout.

3. Host Controller Interface (HCI):

HCI provides a standardized interface between the Bluetooth controller (hardware) and the host (software). This allows for easier integration of BLE into various platforms and operating systems.

4. Generic Attribute Profile (GATT):

GATT defines how BLE devices exchange data using concepts of services, characteristics, and descriptors.

  • Services: Services are collections of characteristics that define the functionality of a BLE device. Examples include the Generic Access Profile (GAP) service for device identification and the Generic Attribute Profile (GATT) service for data exchange.
  • Characteristics: Characteristics contain data values and can be read, written, or notified/indicated to the connected device. Each characteristic has a unique UUID (Universal Unique Identifier).
  • Descriptors: Descriptors provide additional information about a characteristic's value, such as user descriptions or configuration settings.

5. Security and Privacy:

BLE provides various security features to ensure data confidentiality, integrity, and authenticity.

  • Pairing and Bonding: Devices can establish a secure connection through pairing, where they exchange security keys. Bonding allows devices to remember each other for future connections without re-pairing.
  • Encryption: Once paired, data exchanged between devices can be encrypted to prevent eavesdropping and tampering.

6. Profiles and Services:

BLE defines profiles that specify how devices communicate for specific applications. Examples include:

  • Heart Rate Profile: Defines how heart rate monitors communicate heart rate data.
  • Battery Service: Provides information about the battery level of a device.
  • Environmental Sensing Profile: Allows environmental sensors (e.g., temperature, humidity) to communicate data.

7. Application Layer:

At the application layer, developers can create custom applications using the BLE stack. This layer interacts with the GATT layer to read/write characteristics, handle notifications, and implement specific IoT functionalities.

Conclusion:

Bluetooth Low Energy (BLE) in IoT applications offers a robust architecture optimized for low-power, short-range communication. By understanding its physical, link, and application layers, along with profiles and security features, developers can design efficient and secure IoT solutions using BLE technology.