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Gary Barta

John T Armstrong

Allen L Hollister

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.

Multidimensional sieving for high density low collision RFID tag fields

A method is presented for taking an unknown field of transponders and converting them to a slotted Aloha architecture and increasing the throughput allowed by the slotted Aloha architecture by using several different techniques including shortening the time of empty and collided timeslots, implementing a unique random number generator that creates random numbers that are uniquely based on an individual tags location, and on an ability to estimate the total number of transponders and control the offered rate such that throughput is always maximum. While these techniques work well together and produce the most benefit when used together, they are independent techniques and any one may be used alone without the others. Thus a system might use the estimated total number of transponders technique and the timeslot shortening technique, but use a standard random number generator rather one based on transponder location with only a small decrease in overall performance.

Method of communicating in a radio frequency identification system using aloha networks

A method and system for reading RFID tags in a high-density environment using a directional scanning antenna system is provided. The directional scanning antenna system consists of transmit and receive antennas having highly directional antenna patterns which work together to read and locate the tags. In operation both types of antennas are stepped in a circular fashion with respect to each other wherein the transmit antenna's antenna pattern pauses during rotation while the receive antenna pattern sweeps across the radiating antenna's path produced by the transmit antenna such that the antenna patterns produced from each isolate and determine the location of the tags.

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Duarte, CA, United States of America

Gary Barta