Implementation of error-correcting encoded SAW RFID tags

Surface acoustic wave (SAW) based radio frequency identification (RFID) tags are truly passive, and the decoding reliability of SAW RFID system is difficult to be guaranteed. A powerful method to enhance the reliability of RFID systems is the data checksum, i.e. a few calculated bits of code added to an ID data block to verify its complete transmission. Apart from the GOST SAW tags using cyclic redundancy checks (CRCs), rare SAW RFID system adopting the error control technique has been reported till now, mainly because the portion of encoding space for data integrity calibration greatly shrinks the code capacity. In addition, CRC is an error control technique whereby either all or none of information can be obtained, but the position of error cannot be determined. The only way to get the original responses of tags is to repeat the interrogation from the reader. SAW RFID system employing Reed-Solomon (RS) codes is presented. The coding methods and error correction algorithms of Reed-Solomon codes for SAW RFID are described. Random errors are generated using Monte Carlo methods to verify all the correction processing. The decoder will not misdecode and recover an incorrect code word without any indication if the number of simulated errors numbers is within the designed number.