How AoA & AoD Changed
the Direction of Bluetooth
Location Services

Direction Finding Using Angle of Arrival

In the angle of arrival (AoA) method, the device to which direction is being determined, such as a tag in an RTLS solution, transmits a special direction finding signal using a single antenna. The receiving device, such as a locator in that same RTLS solution, has multiple antennae arranged in an array. As the transmitted signal crosses the array, the receiving device sees a signal phase difference due to the difference in distance from each of the antenna in its array to the transmitting antenna. The receiving device takes IQ samples of the signal while switching between the active antenna in the array. Based on the IQ sample data, the receiving device can calculate the relative signal direction. The AoA method of direction finding is intended for use with RTLS as well as proximity solutions, such as item finding and point of interest (PoI) information services.

Direction Finding Using Angle of Departure

In the angle of departure (AoD) method, the device to which direction is being determined, such as a locator beacon in an IPS solution, transmits a special signal using multiple antennae arranged in an array. The receiving device, such as a mobile phone in that same IPS solution, has a single antenna.

As the multiple signals from the transmitting device cross the antenna in the receiving device, the receiving device takes IQ samples. Based on the IQ sample data, the receiving device can calculate the relative signal direction. The AoD method of direction finding is intended for use in IPS solutions, such as those used for wayfinding.

A New Direction for Blue

Key proximity and positioning use cases stand to reap the benefits of the new Bluetooth direction finding feature.

Item Finding Solutions

Item finding solutions stand to experience a big bump in user experience. Once smartphone vendors integrate Bluetooth Direction Finding with AoA support into their phones, item finding solutions will be able to leverage directional information. Which means they’ll not only be able to identify how close a misplaced item is, they’ll also determine its direction, eliminating the need for guesswork when finding lost items.

PoI Information Solutions

PoI information solutions could also benefit from direction finding with AoA being added to smartphones. Imagine a room in a museum with multiple exhibits that has associated beacons. Currently, a PoI information application on a smartphone can inform a user of all the exhibits in the room and allow them to select one to receive additional information. With direction finding support, users will be able to simply point their smartphone at a specific exhibit to get more information on that item.

RTLS Solutions

By implementing direction finding, RTLS solutions could improve location accuracy down to centimeter level in the right deployment environment. RTLS with direction finding will enable a factory to track the location and flow of materials with greater precision while also alerting workers before they go into unsafe work areas.

IPS Solutions

IPS solutions also stand to benefit from direction finding support. Imagine a positioning system that can navigate a fan visiting a large stadium venue not just to their section but to their seat. Or a shopper in a store not just to the area or aisle a product is on but to the shelf. In addition, IPS solutions with direction finding may require fewer locator beacons to achieve greater accuracy, bringing further efficiency to deployments. And the accuracy gained will also provide incremental data and knowledge on the interaction between products and consumers.

The Bluetooth^® community is continually enhancing the technology to address new market opportunities while meeting the ever-expanding needs of traditional markets and use cases. The addition of direction finding is the latest in a series of recent advancements, and it brings established, time-tested methods for determining signal direction to a proven, trusted radio.

Download this paper, Enhancing Bluetooth Location Services with Direction Finding, to learn more about how the Bluetooth community is enhancing Bluetooth Location Services solutions.