loc-201: locate your things with bluetooth direction finding

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LOC-201: Locate your Things with Bluetooth Direction FindingSami Kaislasuo | September 2021

Bluetooth Angle-of-Arrival Technology and system overview

Real-world demonstration of locating assets in an office setting

Silicon Labs offering

Introduction

Silicon Labs Confidential3

Bluetooth Direction Finding: Angle of Arrival (AoA)

An asset wants to broadcast its location

• Continuous tone extension (CTE) is added to the end of a Bluetooth advertisement or connection packet

• Asset can support other Bluetooth functions while being tracked as CTE does not use the payload

• Asset can be a single antenna Bluetooth device supporting Bluetooth 5.1 and AoA

A locator wants to find the asset

• A locator listens for CTE packets and measures IQ data from the CTE payload

• Can perform spherical azimuth and elevation calculation, or pass the IQ data forward to back-end processing

• Locator needs an antenna array, RF switches and Bluetooth 5.1 AoA capable radio

4 Silicon Labs Confidential

Transmitter (TX)

𝜃

Receiver (RX)

Bluetooth Angle-of-Arrival Improves Asset Tracking


𝜃1𝜃2

𝜑1 𝜑2

h h

Asset(x1,y1,z1)

Bluetooth AoA Locators Discover Bluetooth asset tags

Perfrom I/Q sampling for I/Q data

Computes position locally or passed the I/Q data to a central position engine

Need back-end connectivity (ETH or Wi-Fi) to position engine – unless position computed locally

Bluetooth AoA Asset Tags Transmit CTE in beacons or connection packets

Can transmit or receive data as well

Local Position Engine Collects data from all Bluetooth AoA locators

Can perform triangulation and trilateration

Exposes the data to end user applications

Cloud Position Engine Optionally the position engine

can run in the cloud

Cloud Position Engine

Locator Locator

Local Position Engine


Bluetooth Angle-of-Arrival System Components

Battery powered, mobile

Various use cases

Stationary

Mains powered

Stand-alone, or integrated (i.e. access points)

Combining tag position information as location

Asset Tracking

Tools, System Deployment

Heatmaps, Zones

System Maintenance

Locators Positioning Engine & ToolsAsset tag

System Architecture – Angle and IQ data


BT stack

EFR32

Tag app

Tag



BT stack

EFR32

Tag app

RTL libApp

NCP client

MQTT client

BT stack

EFR32

NCP client

IQ samples

BT stack

EFR32

NCP client

IQ samples

BT stack

EFR32

NCP client

IQ samples

00 0

Host

Target

Tag

RTL libApp

NCP client

MQTT client

RTL libApp

NCP client

MQTT client



BT stack

EFR32

Tag app

Aggregator Network (MQTT broker)

RTL libApp

MQTT client

Application

MQTT client

Locator positions

Angles Position Angles and IQ samples Position

RTL libApp

NCP client

MQTT client

Angle IQ samples Angle IQ samples Angle IQ samples

BT stack

EFR32

NCP client

IQ samples

BT stack

EFR32

NCP client

IQ samples

BT stack

EFR32

NCP client

IQ samples

00 0

Host

Target

Tag

RTL libApp

NCP client

MQTT client

RTL libApp

NCP client

MQTT client

Silicon Labs Real-Time Location Library - Overview


Azimuth & Elevation

Silicon Labs Real-Time Location Library - Overview


Azimuth & Elevation Calculating x,y,z-coordinates

Video – Locate your Things with Bluetooth Direction Finding

12

Short intro to Direction-Finding

Demonstrator – package tracking in an office setup with Silicon Labs reference hardware and software used

Evaluation tools, demonstrator setup and Direction-Finding deployment

Silicon Labs Confidential

Silicon Labs Offering

Performance


Tag

Battery lifetime (CR2032) ~3.5y2s interval, Silicon Labs enhanced

COGS As low as <$1.0 In volumes

RTL library

Tags Up to thousands Silicon Labs enhanced

Angle computationCortex-A class recommended, RAM 40kB

2s interval, Silicon Labs enhanced

Accuracy – Angle +-3 degrees GSDK v3.4

Accuracy - Elevation +-5 degrees GSDK v3.4

Distance between locators Area

Accuracy [m]SLWRB4185A 4 locators *

5m 25m^2 < 0.4 m

10m 100m^2 < 0.6 m

15m 225m^2 < 0.8 m

*) inside the area between locators excluding the locations within 1m distance from any locator

Availability

Software available now

• Download GSDK for access to Silicon Labs Bluetooth stack with Direction Finding support and examples and the RTL library

Tag hardware

• EFR32BG22 SoCs and Modules

• Reference designs available at silabs.com

Infrastructure hardware

• Circular-Polarized Antenna Array Reference (Order code: SLWRB4185)

▸ For availability contact Silicon Labs sales

S A M I K A I S L A S U O | S E P T E M B E R 2 0 2 1

Thank you

loc-201: locate your things with bluetooth direction finding

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