Memory-Efficient Anti-Collision Algorithm in RFID system

Radio Frequency Identification (RFID) systems have come out as an attractive solution for object identification by using radio frequency transmission.An anti-collision algorithm provides a method for an RFID reader to identify multiple tags at the same time. The query tree (QT) anti-collision algorithm based on the ISO 15693 standard is considered in this book. This al-gorithm requires the reader to repeatedly send a request command containing a mask. Only tags whose unique identification numbers (UIDs) match this mask respond to the reader. The mask length varies from 1 bit at the top of the query tree to the maximum of 64 bits, which is the length of a UID. ISO 15693 specifies the reader to store all masks in a memory stack as the QT algorithm proceeds. This implementation is inefficient since it requires a considerably large amount of memory for the reader implementation. An algorithm compatible with the memory constraint of the microcontroller is developed to store only the current mask with the capability to trace back all the masks previously stored in the memory stack. It can be used in a practical reader implementation especially when the memory size is limited.