Abstract: A computerized method of generating and transmitting a message to a plurality of recipient devices has the steps of obtaining a plurality of recipient multicast identifications (IDs) for the plurality of recipient devices, losslessly encoding the recipient multicast IDs into one or more codewords such that the total length of the one or more codewords is shorter than that of the recipient multicast IDs, generating the message by encapsulating at least the one or more codewords into a payload of the message, and transmitting the generated message to a network. When receiving such as message, a listener device decodes the one or more codewords to determine if it is a recipient.

Abstract: A method and system for tracking mobile objects in a site are disclosed. The system comprises a computer cloud communicating with one or more imaging devices and one or more tag devices. Each tag device is attached to a mobile object, and has one or more sensors for sensing the motion of the mobile object. The computer cloud visually tracks mobile objects in the site using image streams captured by the imaging devices, and uses measurements obtained from tag devices to resolve ambiguity occurred in mobile object tracking. The computer cloud uses an optimization method to reduce power consumption of tag devices.