With the release of Bluetooth specification 5.1, Bluetooth direction finding capabilities have become a cost-effective, low-power solution for location services. In this Tech Talks session, Silicon Labs field applications engineer, Claudio Filho, explains the advantages of using Bluetooth AoX direction finding over other Wi-Fi or received signal strength indicator (RSSI)-based solutions. You can watch the entire Bluetooth AoX session here and register now for future Tech Talks. Some highlights from Claudio’s presentation are below.   

Use Cases for AoX Location Services

Asset management and indoor navigation have increasingly become an enterprise requirement. The following are use cases where Bluetooth AoX (angle of arrival or angle of departure) solutions provide optimal proximity and location services:

• Asset management in hospitals
• Indoor navigation where GPS isn’t reliable (inside malls, airports, in grocery stores)
• Point of interest (PoI) marketing and information services
  • Museums – send information to visitor smartphones
  • Retail – directly market to nearby customers with coupons
• Access control – restrict access in certain areas and enable auto-entry for authorized personnel. Also, keyless entry to buildings and cars.

Why Bluetooth Direction Finding?

Bluetooth direction finding offers the following key advantages:

• Ubiquitous – Most smartphones and electronic products already integrate Bluetooth Low Energy (LE )
• Lowest power technology for wireless tags – operates 5 to 10 years on a coin cell battery
• Lowest bill of materials (BOM) cost for tags – less than $1 in high volume

Other technologies for direction finding are available, such as Ultra-Wide Band (UWB), but they are power-hungry and increase BOM cost for components such as an extra radio, passives and antennas.

How Does Angle of Arrival (AoA) and Angle of Departure (AoD) Enable Direction Finding?

Bluetooth direction finding relies on two methods for calculating location: Angle of Arrival (AoA) and Angle of Departure (AoD). With AoA, a mobile transmitter, which is a simple tag with a single antenna, transmits a signal to a receiver comprised of multiple antennas, called “locators”, positioned at fixed locations. As the signal passes to each antenna, a difference in phase shift occurs, which can be used to calculate the Azimuth and elevation of the transmitter. By collecting these angles, a position engine associated with the locators calculates the absolute position of the tag.  

With AoD, the direction finding process is reversed. In this case, the antennas are the transmitters and wireless tags act as receivers. Each receiver computes its own positioning based on calculated data from the transmitter. Because the computing power required for an AoD receiver is much higher than in AoA, this technology is not widely used today.

Our Direction Finding Solutions

We offer several hardware and software direction finding solutions for asset tags, locators and beacons.  

EFR32BG21 is a simple, RSSI solution for generic gateways and is optimized for best performance. EFR32BG22 SoC (BG22) is our most cost-competitive Bluetooth AoX device. It features ultra-low transmit and receive power and achieves 1.4 uA with full RAM retention in Sleep Mode. BG22 also comes with advanced security features such as secure boot with root of trust, a one-time programmable key, and secure debug lock and unlock. A forthcoming BG22 reference design will include schematics, PCB and BOM, and a 4x4 antenna array that provides AoA performance down to 1 degree of accuracy.

Software for tags and beacons includes our standard stack, along with an added CTE implementation and real-time location library used to collect IQ samples and make calculations.

Silicon Labs and Quuppa

According to Claudio, many customers are interested in AoA technology but lack the infrastructure and resources to deploy it. For this reason, we have partnered with Quuppa, a technology company with more than 15 years of location services experience offering a ready-to-install, AoA infrastructure including locators and position engines. Quuppa locators and position engines can track any EFR32BG22 device, helping customers get to market much faster than having to develop all the infrastructure on their own.    

The session ended with Claudio answering questions from the audience. Click here for the Q&A transcript. For more information about AoA technologies, contact your Silicon Sales representative.