Multidimensional sieving for high density low collision rfid tag fields

Abstract

A system comprising an RFID Reader and an array of RFID Tags, where the tags have the ability to measure physical signal properties such as FM deviation and Received Signal Strength as examples and use these measurements to create a means to refrain from responding to the Reader, unless the measured values fall inside a range determined by a built in algorithm or decision tree or by the Reader and transmitted to the array of Tags in an outbound message. The system may also use non-physical parameters, including tokens sent by the Interrogator/Reader to the Tag field. Moreover, physical parameters may be divided into maskable and unmaskable parameters. Signal frequency is not maskable by the environment, for example, but signal amplitude and phase are maskable by the environment during propagation. Additionally, the number, the nature and the range of each Multidimensional Variable are set by the Interrogator at the start of a session. In this way, foreknowledge or good estimates of the tag population will lead to higher efficiency operation.