The paper tests the market readiness of the Bluetooth 5.1 direction finding by experimentally evaluating the performance of the AoA mechanism. The authors took Software-Defined Radios(SDR) manufactured by Ettus Research and emulated Bluetooth AoA data in order to assess the potential accuracy and security.
The results show that accurate angular detection is limited to a restricted range:
“Observe that the error is below 85 cm for more than 95% of the positions. However, this is far from meeting the centimetre level accuracy expected by IoT applications, since the absolute positioning error is <10 cm only in 15% of cases. Although offering sub-meter accuracy, is far from achieving centimetre-level precision.”
It was found that a malicious device can easily alter the truthfulness of the measured AoA data by tampering with the packet structure because the Bluetooth 5.1 standard doesn’t enforce any security provisions. The researchers suggest an improvement to the standard, by changing the receiver, so that instead of using one main antenna and switching to the other only for measuring the phase-delay, it keeps the other antenna active for the next packet to be received.
The paper provides an analysis of the challenges the antenna designer faces when creating an AoA solution. Issues include orientation and polarization, matching, coupling, reflections, phase center, and physical size. Designing and creating antennas can easily lead to inconsistent results due to the affects of hardware, cables and other testing equipment in the vicinity.
The interview mentions how the Bluetooth 5.1 direction finding standard might need to evolve to provide less ‘chatty’, shorter communication in order to be suitable for all usecases, particularly those that are battery powered or need to have very large numbers of assets being tracked.
It’s also mentioned that the Bluetooth direction finding standard doesn’t cover tools needed to setup and control direction finding systems. It also doesn’t specify antenna design that’s a complex area.
As we have also experienced, there’s mention how some Ultra Wideband (UWB) vendors and ISVs are moving to Bluetooth for reduced costs, reduced power requirements and compatibility with other devices (tablets, phones and single board computers) that also use Bluetooth LE.
We sometimes get asked for location beacons or which beacons are best for determining location. All beacons can be used for locating. While there are physical aspects such as battery size/life and waterproofing that make some beacons more suitable for some scenarios, locating capability is determined more by the software used rather than the beacons themselves.
If you have been attracted to Bluetooth by recent announcements on Bluetooth direction finding, be aware that no ready-made hardware or software solutions exist yet. It will take a while, perhaps years, before silicon vendors support Bluetooth 5.1 direction finding, silicon vendors create SDKs and hardware manufacturers create hardware.
“Should smartphone vendors choose to include Bluetooth direction finding with AoA support in their products, item finding solutions could be enhanced to provide directional information.”
As with the move from Bluetooth 4 to Bluetooth 5 it’s going to be while before we see (non Quuppa) products with direction finding. This feature requires specific hardware and software. Before that, it needs SDKs from the SoC vendors. Existing smartphones, beacons and gateways won’t be able to be upgraded.