Bluetooth Location Services: Angle of Arrival (AoA) and Angle of Departure (AoD)

The Bluetooth specification enhances location services with a direction-finding feature that makes it possible to detect the direction of a Bluetooth signal. With Bluetooth Location Services, developers can bring products to market that understand device direction and achieve sub-meter location accuracy.

Applications for Bluetooth Location Services

Bluetooth Beaconing - Silicon Labs

Smart Retail

Smart Healthcare

Bluetooth Real-Time Locationing - Silicon Labs

Smart Warehouses

Bluetooth Indoor Positioning - Silicon Labs

Smart Buildings

Silicon Labs Bluetooth Direction Finding Solution


Bluetooth Direction Finding Demo

Featuring our Antenna Array Board and BG22 Asset Tags

BG22 Bluetooth Dual Polarized Antenna Array Radio Board

The kit provides a 4x4 Antenna Array board for evaluation and development of Angle of Arrival (AoA) and Angle of Departure (AoD) support provided in the Bluetooth 5.1 specification.

  • Bluetooth stack with Direction Finding
  • EFR32BG24 SoCs
  • EFR32BG22 SoCs and SiP Module
  • Antenna reference designs and radio boards

Understanding Angle of Arrival and Angle of Departure

Angle of Arrival (AoA)

Angle of Arrival - Silicon Labs
  • Assets broadcast (TX) their location to an AoA locator such as a wireless access point (AP), connected light or smart luminaire
  • Locators measure the signal's arrival angle

Angle of Departure (AoD)

Angle of Departure - Silicon Labs
  • Beacons transmit AoD information such as coordinates using multiple antennas
  • Mobile devices receive the beacons and calculates position

Angle of Arrival Design Considerations

Angle of Arrival Design Considerations - Silicon Labs
  • Assets only need a single antenna, can be low power, and simultaneously support additional Bluetooth LE functionality
  • Locators require antenna arrays
  • Edge gateways process angle readings and communicate to an asset management system in the cloud to determine device location

Angle of Departure Design Considerations

Angle of Departure Design Considerations - Silicon Labs
  • Beacons require 4 x 4 antenna arrays
  • Mobile devices need to support AoD algorithms
  • Beacon coordinates must be known by the location services system
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