Battery assisted rfid system rf power control and interference mitigation methods

Abstract

The present invention discloses battery assisted RFID system RF 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. These methods enhance system reliability when employing battery assisted RFID tags that operate with sensitive transistor based square law tag receivers and highly sensitive RFID readers intended to take advantage of outstanding tag sensitivity. Further enhancement is achieved via design of system command sets and tag state machine behavior that optimally support the power level operations, power level operations that span across tag hibernation and normal modes, and that otherwise control system interference. Embodiments of the present invention are also enhanced with receiver training and synchronizing methods suited to the high tag sensitivity and need for dynamic range state switching. These enhancements may employ pseudo-random sequence based receiver training, activation signaling, and frame synchronizing.