The channel of radio frequency identi cation (RFID) can be modeled as a cascaded channel consisting of a forward link and a backscatter link. The correlation between the forward and backscatter links strongly affects the bit-error-rate (BER) performance of RFID systems. In this paper, we analytically study how the link correlation affects the BER performance of a single-input, multiple-output (SIMO) RFID system. We derive exact forms and asymptotic forms of the BER for SIMO RFID systems with maximal ratio combining (MRC) at the reader side. The asymptotic forms provides an insight into the relationship between the link correlation and the BER performance. It is shown that the BER is an increasing function of the magnitude of link correlation in the high SNR regime and is proportional to (1 + ρ2 )L /(1 − ρ2 )L in the extremely high SNR regime for an L branch channel.
Chen He, Z. Jane Wang