A system for tracking entities at a site comprises a mesh of radio frequency identification (RFID) tags. Each of the tracked entities, which may move about the site, is associated with and attached to a portable RFID tag. Each RFID tag is at least periodically caused to transmit a signal that includes an identification of the RFID tag. The signal is received by other RFID tags that are within range, which determine a location indicative parameter. Some of the RFID tags receiving the signal are fixed at predefined locations. Specific fixed RFID tags are designated as controller nodes. Data comprising an identification of the RFID tag receiving a signal, the location indicative parameter, and the identification of the portable RFID tag transmitting the signal are communicated to a location engine server, which processes the data to determine at least a relative position of the portable RFID tags on the site.