Battery assisted rfid tag receiver training and synchronization methods

Abstract

Embodiments of the present invention provide for enhanced RFID tag receiver training and synchronizing methods suited to the high tag sensitivity that results from use of transistor detector based square law tag receivers and tag hibernation to maximize battery life. These enhancements may employ pseudo-random sequence based receiver training, activation signaling, and frame synchronizing. Embodiments of the present invention also provide RFID systems having battery-assisted, Semi-Passive RFID tags that operate with sensitive tag receivers utilizing a plurality of tag receiver dynamic range states. Further enhancement is achieved via design of system command sets and tag state machine behavior that control system interference and allow maximum usage of high sensitivity. Command set design also allows for convenient expansion to active transmitters and receivers in tags operating within the same system. Additional system performance support is attained via power leveling methods that optimize the amount of transmitted power and interference from a reader in relation to the sensitivity of the RFID tags, their ranges from the reader, and the unique physics of the backscatter RFID radio link.