Techniques for detecting the presence of a tag are described. According to one aspect of the present invention, a plurality of devices are deployed around an establishment, each of the devices is executing a client module to communicate with a server and receive a broadcast from a tag attached to an object (e.g., a human being or an item). As the object approaches to a device, the broadcast from the tag is received by a device that reports to the server. As a result, the server executing a server module can determine a movement trajectory of the object from those devices that have received the broadcast from the tag. One embodiment of the present invention can be used to track an asset or facilitate a location-based service to a user wearing the tag.