Performance of BCH Codes and Transmit Diversity for MISO UHF RFID Communication

Radio Frequency Identification (RFID) is used in environments with significant fading characteristic. In this paper the Electronic Product Code (EPC) Class-1 Gen-2 protocol is extended by spatial diversity (SD) and Forward Error Correction (FEC) in order to improve the transmission reliability. A dyadic backscatter channel is used. The respective channel model gives a good approximation for the RFID small scale fading characteristic. Based on simulations of the bit error-rate (BER) and the packet error-rate (PER) the improvement using FEC (a BCH code) and SD (with two tag antennas) are presented and the trade-off between FEC and SD is discussed. It is shown that a BCH encoded transmission can lead to 8 dB coding gain which is relatively constant for varying channel parameters. Higher gains (up to 27 dB) can be achieved by using two tag antennas, but varying the channel parameters results in a higher variance of the gain due to different correlation scenarios.