Bluetooth Direction Finding: Angle of Arrival (AoA) and Angle of Departure (AoD)
The Bluetooth 5.1 specification enhances location services with a direction finding feature that makes it possible to detect the direction of a Bluetooth signal. With Bluetooth direction finding, developers can bring products to market that understand device direction and achieve sub-meter location accuracy.
Applications for Bluetooth Direction Finding
Point-of-Interest
Proximity marketing
Item Finding
Personal property tags
Real-Time Locating (RTLS)
Asset tracking
Indoor Positioning
Wayfinding
Angle of Arrival (AoA)
- 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)
- Beacons transmit AoD information such as coordinates using multiple antennas
- Mobile devices, including smartphones receive the beacons and calculates position
Bluetooth Angle Estimation for Real-Time Locationing Whitepaper
Bluetooth Angle Estimation for Real- Time Locationing
AoA Design Considerations
- Assets only need a single antenna, can be low power, and simultaneously support additional Bluetooth LE functionality
- Locators require 3 x 3 or 4 x 4 antenna arrays and switches
- Edge gateways process angle readings and communicate to an asset management system in the cloud to determine device location
AoD Design Considerations
- Beacons require 3 x 3 or 4 x 4 antenna arrays and switches
- Mobile devices like smartphones need to support AoD algorithms
- Beacon coordinates must be known by the location services system
Silicon Labs Direction Finding Solution
- Bluetooth 5.1 stack with Direction Finding
- Wireless Gecko EFR32BG13 Bluetooth SoC and BGM13 modules
- Antenna reference designs and radio boards