US Patent 9619989 Asset tracking systems and methods

An asset tracking system has a plurality of anchors. A tag communicates with the anchors as it is moved by a user being tracked by the system, and data based on communication between the tag and at least one of the anchors is transmitted to a server. The server determines a location of the tag based on the data and detects an occurrence of an event based on the location. The server also transmits to each of the anchors a tag alert message having a tag identifier identifying the tag and an event indicator associated with the occurrence of the event. At least one of the anchors transmits the tag identifier and the event indicator to the tag, which issues a warning to the user in response to tag alert message.