Impact of the correlation between forward and backscatter channels on RFID system performance

The channel of radio frequency identification (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 de rive 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 perfor mance. 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.