Forward error correction in passive UHF Gen2 communications

In this paper, we present an evaluation of two forward error correction (FEC) codes, Hamming codes and Reed-Solomon codes, used in the tag communications within the ISO 18000-63 (Gen2) passive Radio Frequency Identification (RFID) tag identification protocol. Gen2 tags utilize backscatter communication, and their communication signal is often -60dBm or lower when it reaches the reader. Signals at this power level are very susceptible to noise and other interference effects, and they are at the limits of the typical reader´s receive sensitivity. The communications from the Gen2 tag to the reader are protected with a Cyclic Redundancy Check (CRC) that detects, but does not correct, potential communication errors. We present an evaluation of Hamming codes and Reed-Solomon codes used within the tag´s communication during the Gen2 identification process. We find that the Hamming codes provide minimal improvement over CRC and do not perform well under high error rates. The Reed-Solomon codes, in contrast, are able to correct nearly all common transmission errors in an environment with a bit error rate of 0.025, resulting in a message retransmission rate of less than 2% as compared to a retransmission rate of approximately 65% for messages protected with just a CRC.