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 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


Bluetooth Angle Estimation for Real-Time Locationing

Learn the basics of angle of arrival and angle of departure and the theory for estimating direction of arrival in this whitepaper.

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