How accurate is Bluetooth AOA?

At a time when indoor positioning technology is booming, Bluetooth AOA (angle of arrival) technology has gradually become the focus of attention in many fields due to its unique positioning principle and significant advantages. Whether in shopping mall navigation, industrial tracking, smart home, security monitoring, etc., Bluetooth AOA technology has shown strong application potential. So, how accurate is Bluetooth AOA technology? Let's take a look from the following aspects.

Theoretical positioning accuracy

Bluetooth AOA technology detects the phase difference of the signal from a single transmitting source through the antenna array at the receiving end, and then calculates the angle of arrival of the signal through an algorithm, and then combines triangulation and other methods to determine the location of the target device. Under ideal conditions, that is, in an open and interference-free environment, Bluetooth AOA technology can achieve centimeter-level positioning accuracy. For example, in some professional test scenarios, its positioning error can be controlled within 30 cm. This high-precision positioning capability provides strong support for many applications that require strict location information.

 

Influencing factors and accuracy performance in actual environments

Multipath effect

In actual application environments, signals are often affected by multipath effects. When the signal encounters obstacles such as buildings and metal objects during propagation, reflection, refraction and scattering will occur, causing the receiver to receive signals from multiple different paths. These signals interfere with each other, causing deviations in the measurement of phase difference, thereby reducing positioning accuracy. However, Bluetooth AOA technology can reduce the impact of multipath effect to a certain extent by using technologies such as beamforming to strengthen and amplify signals from different directions, and then determine the arrival angle according to the information strength in different directions. However, even so, in an environment with severe multipath effect, the positioning accuracy may still decrease, and the error may increase to less than 1 meter.

Interfering materials such as metal

Metal objects have strong reflection and absorption effects on Bluetooth signals. When there are a large number of metal objects around the Bluetooth AOA positioning system, the signal will be reflected and interfered, causing the signal strength and phase received by the receiver to change, affecting the accuracy of positioning. For example, in an environment with dense metal equipment such as a chemical plant, the positioning accuracy of Bluetooth AOA technology may be affected to a certain extent, but through reasonable base station layout and algorithm optimization, it can still maintain a high accuracy of less than 1 meter.

Base station deployment height and density

The deployment height and density of Bluetooth AOA base stations will also affect positioning accuracy. Generally speaking, the deployment height of the base station is closely related to the coverage range, and the positioning coverage range is about 1.5 times the deployment height. For example, if the base station is deployed at a height of 5 meters, its coverage radius is 6 meters to 7.5 meters. At the same time, the greater the density of base stations, the richer the received signal information and the higher the positioning accuracy. In practical applications, the positioning accuracy can be effectively improved by rationally planning the deployment height and density of base stations.

 

Comparison with other positioning technologies

Comparison with Bluetooth RSSI positioning

Bluetooth RSSI (received signal strength indication) positioning is based on signal strength to infer the distance, thereby determining the location of the target device. However, signal strength is easily affected by environmental factors such as obstacles and signal interference, resulting in unstable positioning accuracy, which can only be up to about 2 meters. In contrast, Bluetooth AOA technology determines the position by measuring the angle of signal arrival, is not affected by signal strength fluctuations, has higher positioning accuracy, can achieve centimeter-level positioning, and has obvious advantages in positioning accuracy.

Compared with UWB positioning

UWB (ultra-wideband) positioning technology is also a high-precision indoor positioning technology with an accuracy range of 0.1-1 meters. Bluetooth AOA technology is similar to UWB positioning technology in terms of accuracy, but has advantages in terms of cost and complexity of base station deployment. One Bluetooth AOA base station can achieve centimeter-level positioning, while UWB base stations must be grouped in four to achieve centimeter-level positioning. In environments with more rooms, such as nursing homes, prisons, and detention centers, Bluetooth AOA positioning uses fewer base stations, and the price of positioning terminals using Bluetooth chips is much cheaper than UWB positioning terminals.

 

Accuracy performance in different application scenarios

Mall navigation

In the mall, consumers can receive accurate navigation instructions through their mobile phones and quickly find the target store or product. Bluetooth AOA technology can provide consumers with positioning accuracy within 0.5 meters, significantly improving the shopping experience. For example, Suzhou Xindao Intelligent's solution has been successfully applied to mall traffic optimization and precision marketing. Through high-precision positioning, it helps malls better understand consumers' behavior trajectories and optimize store layout and product display.

Industrial Tracking

In factories, personnel, equipment and materials can be tracked in real time through Bluetooth AOA tags to optimize production processes. With centimeter-level positioning accuracy, factories can accurately grasp the location information of personnel and equipment, achieve reasonable scheduling and management, and improve production efficiency. For example, centimeter-level real-time tracking of pallets and transportation equipment can reduce manual inventory costs.

Hospital Management

Hospitals use patient bracelets with Bluetooth AOA tags to track patient locations, combine electronic fence functions to prevent high-risk patients from getting lost, and optimize the efficiency of nursing staff scheduling. Its positioning accuracy can meet the hospital's needs for personnel location management, ensure patient safety and the smooth progress of medical work.

 

Bluetooth AOA technology can achieve centimeter-level high-precision positioning under theoretical conditions. Although it will be affected by factors such as multipath effects and metal interference in actual applications, it can still maintain a high positioning accuracy through reasonable technical means and base station deployment. Compared with other positioning technologies, Bluetooth AOA technology has unique advantages in accuracy, cost and base station deployment complexity, and can show good positioning effects in different application scenarios such as shopping mall navigation, industrial tracking, and hospital management.