Angle of Arrival is a direction-finding feature introduced with Bluetooth 5.1. Instead of estimating distance from how strong a signal is, it measures the angle the signal comes from, which makes indoor positioning far more precise.
Each AoA anchor contains an array of antennas. A Bluetooth tag broadcasts a short packet, and the tiny phase differences between the antennas reveal the direction it came from. Combining the angles measured by several anchors gives the tag's X and Y position. The Angle of Arrival article explains it in detail, and AoA anchors and gateways covers installation: anchors sit in fixed positions on the ceiling and only need power and network.
Compared with signal-strength (RSSI) methods, AoA offers sub-metre accuracy, low-power tags that last for years on a coin battery, and no cameras or personal devices. In retail, sub-metre precision is what makes shelf-level metrics possible: to measure visual contact and engagement you need to know in front of which bay a trolley slowed down, not just which aisle it was in (positioning accuracy).
Shoppermotion uses AoA both for in-store analytics, with tags on trolleys and baskets, and for its AoA RTLS, which locates assets and people in factories, warehouses and venues. You can test it with the AoA API free demo.