GPS technology has become a mainstream solution for outdoor positioning and asset tracking, however, there is yet to be an equally widespread technology for indoor location services. Ultra-Wide Band (UWB), Wi-Fi and RSSI-based solutions have been considered as possible solutions for the challenge of accurate indoor positioning and asset tracking but were found to have limitations. A key benefit of RSSI is that it requires only one antenna per device, eliminating the complexity, cost, and size of antenna arrays. However it lacks precision, with the technique offering an accuracy of 3 to 5 meters. Another direction-finding technique is known as Time of Arrival, which is the travel time of a radio signal from a single transmitter to a remote single receiver. This method also requires only one antenna per device and offers higher accuracy close to 1 metre, but the downside is the requirement for a highly accurate synchronized clock on each device. In this context, Bluetooth has the benefit of being a very low power and low cost technology that is easily accessible and mainstream. Bluetooth Low Energy is also widely adopted in smartphones and tablets, enabling these devices to be easily used in IoT applications.
To respond to the growing demands and expectations of location-based service providers and their customers for indoor solutions, Bluetooth SIG has announced Bluetooth Low Energy 5.1, a new speci̇fi̇cati̇on ai̇mi̇ng to i̇mprove sub-meter accuracy in positioning and direction finding, which can be especially beneficial for indoor location services. It is ideal for applications such as indoor navigation, tracking and real-time locating of assets, finding personal items with property tags and point of interest engagement with contextual proximity marketing. These capabilities can be extremely useful in many contexts, such as in airports, malls and other large venues with frequent foot traffic.
BLE 5.1 relies on two methods called the angle of arrival (AoA) and angle of departure (AoD). One of the two devices must have multiple antennas, and the data received from those antennas can be used to identify the direction the Bluetooth signal is coming from. With AoA method, the transmitter broadcasts its location to an AoA locator, which measures the signal’s arrival angle. With AoD method, a transmitter with multiple antennas sends the signal using an array of antennas, and the receiver receives all signals through a single antenna, but is also able to analyze the difference between the signals to estimate the direction from which they originated. With angle and direction information, the system is able to accurately position the device. This will allow indoor location services and proximity solutions to have a higher level of accuracy. The configuration also comes with faster connection capabilities, allowing Bluetooth devices to connect faster, spending less energy. BLE 5.1 comes with many new opportunities but also limitations. Studies have shown that while sub 1 meter accuracy is achieved, positioning within a few centimeters still remains difficult.
The Direction Finding feature of Bluetooth 5.1 will significantly increase the accuracy for indoor location-based services while keeping the costs low, which means that as far as we can see, the future of indoor positioning systems is BLE 5.1. As more and more developers work on this technology, the possible applications and usage cases will also increase, making the demand for this technology to increase as well. In fact Bluetooth SIG estimates that more than 400 million tracking devices will be delivered worldwide by 2022, making the new specification an important development for LBS providers for the foreseeable future.