AoX Bluetooth direction finding technology has a bright future
The direction measurement positioning of Bluetooth AoX is different from the previous positioning based on Bluetooth beacons or RSSI. The positioning accuracy based on Bluetooth beacons or RSSI is not very high (although it is also meter-level positioning, but the accuracy is generally 2-5 meters). The Bluetooth 51 specification stipulates that AoA must be based on connection or periodic broadcast, both of which require the locator to allocate a certain amount of memory for each test target, which will be a big limitation for devices with limited RAM.
When it comes to positioning and indoor positioning, whether it is GPS positioning, WIFI positioning, network positioning or UWB ultra-high frequency positioning, continuous improvement of accuracy is definitely the direction of these indoor positioning. With the release of the Bluetooth 5.1 standard, Bluetooth direction finding technology has also attracted widespread attention and has become a low-cost, low-power indoor positioning technology.
Why is Bluetooth AoX positioning technology suitable for indoor positioning services?
First of all, no matter what kind of positioning technology, we first focus on its positioning accuracy. Bluetooth direction measurement can reach an accuracy of less than 1m. It should be pointed out that the direction measurement positioning of Bluetooth AoX is different from the previous positioning based on Bluetooth beacons or RSSI. The positioning accuracy based on Bluetooth beacons or RSSI is not very high (although it is also meter-level positioning, but the accuracy is generally 2-5 meters. ).In addition, the direction finding positioning power consumption of Bluetooth AoX is lower than the previous Bluetooth positioning technology. According to the current Bluetooth direction finding technology, it can maintain a working life of 5 to 10 years when powered by a coin cell battery. Another more sensitive consideration is BOM cost. According to the current market price of ADM823SYKSZ-R7 chip components, the cost of designing this Bluetooth tag is no more than 1 USD, of course, the premise is that the quantity is large.
The Bluetooth AoX direction finding function can be easily embedded into other Bluetooth products, such as current wearables, medical devices, and does not require other hardware changes. This very convenient technical feature improvement saves a lot of difficulty and worry. A unified standard for Bluetooth global standards is also more conducive to cooperation.
The main application scenarios of the current Bluetooth AoX positioning technology
Asset management is a very large application scenario of Bluetooth AoX positioning technology, and the potential market demand is also very large. These scenarios mainly use location technology to track important assets. According to market estimates given by Gartner, more than 60% of enterprises require indoor asset tracking.
Another familiar application scenario is indoor navigation. This application is different from the indoor navigation target of mobile robots. The precise positioning of the Bluetooth AoX positioning technology is rice-level navigation, similar to finding the target positioning through a mobile application, and then performing indoor navigation. Although there are also technologies for positioning through mobile base stations, according to personal experience, base station positioning is sometimes not so accurate and cannot optimize indoor paths.
Bluetooth Direction Finding: Angle of Arrival (AoA) and Angle of Departure (AoD)
The structure of Bluetooth direction finding angle of arrival is not complicated, with one transmitter and one receiver. The transmitter transmits a radio broadcast, and the receiver knows the direction of the transmitter by measuring the angle at which the radio arrives. The basic principle is not complicated, and the position can be pinpointed with multiple measurements.
For an asset, if the asset wants accurate positioning, it just needs to add a CTE after the Bluetooth broadcast or connection packet. The CTE doesn't take up the entire bluetooth packet, it guarantees the existing bluetooth functionality. A single Bluetooth antenna can measure, no additional hardware is required, only software upgrades are required.
For locator, IQdata needs to be obtained from CTE, and azimuth and altitude can be calculated based on IQdata. Of course, IQdata can also be transmitted to the backend for processing. Therefore, the locator requires an antenna array, which is one of the few hardware requirements not complicated.
The Bluetooth 5.1 specification stipulates that AoA must be based on connection or periodic broadcast, both of which require the locator to allocate a certain amount of memory for each test target, which will be very restrictive for devices with limited RAM. On the AoD side, the challenges are synchronous. Synchronization requires RX to take a long time, and inevitably the software required to test the target will be more complex. To address the limitation of AoA, the CTE can be placed after the extended broadcast of Bluetooth 5.0, rather than after the periodic broadcast or connection packet. This can greatly reduce memory requirements. We only touch on the principle of extended broadcasting, which also relieves a considerable software burden at the test target and is a leading method for improving the scalability of AoA.
This seemingly basic capability significantly improves the capabilities of Bluetooth location services. Although there is still a certain distance from large-scale commercial use, the prospect of Bluetooth measuring indoor positioning is huge, and many BLE manufacturers are beginning to lay out in this direction.