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
Bluetooth Modules for AoA Beacons
| Part Number | Buy | Data Sheet | Kit | Bluetooth 5 | Bluetooth Mesh | Bluetooth 5.1 | Dimensions (mm) | TX Power (dBm) | RX Sensitivity (dBm) | MCU Core |
|---|---|---|---|---|---|---|---|---|---|---|
| BGM13S |  |
 |
SLWRB4305A and SLWRB4305C | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | 6.5 x 6.5 x 1.4 | +18 or +8 | -94.1 | ARM® Cortex™-M4 |
| BGM13P | |
|
SLWRB4306A and SLWRB4306B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | 12.9 x 15.0 x 2.2 |
+8 | -94.8 | ARM Cortex-M4 |
Bluetooth SoCs for AoA Locators and AoD Beacons
| Part Number | Buy | Data Sheet | Kit | Bluetooth 5 | Bluetooth Mesh | Bluetooth 5.1 | Package | TX Current | RX Sensitivity (dBm) | MCU Core |
|---|---|---|---|---|---|---|---|---|---|---|
| EFR32BG13P532F512GM32 | |
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN32 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P532F512GM48 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN48 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P632F512GM32 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN32 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P632F512GM48 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN48 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P632F512IM32 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN32 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P632F512IM48 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN48 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P732F512GM32 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN32 | 8.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P732F512GM48 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN48 | 9.5 | -94.8 (1 Mbps 2 GFSK) | ARM Cortex-M4 |
| EFR32BG13P733F512GM48 |
|
|
SLWSTK6020B | 2M PHY; LE Long Range; ADV Extensions | Yes | AoA, GATT caching | QFN48 | 9.5 | -103.3-94.8 (1 Mbps 2 GFSK); -126.2 (600 bps, GFSK, 915 MHz) | ARM Cortex-M4 |
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