Performance Analysis of FAS-Aided Backscatter Communications

In this letter, we study the performance of backscatter communications (BC) over the position-flexible fluid antenna system (FAS) technology. We consider a situation where a single fixed-antenna source sends information to a FAS reader through the wireless forward (i.e., source-to-tag) and backscatter (i.e., tag-to-reader) channels. We first derive the cumulative distribution function (CDF) of the equivalent channel at the FAS receiver, and obtain closed-form expressions for the outage probability (OP) and the delay outage rate (DOR) assuming a correlated Rayleigh distribution. To gain more insights into the system performance, we present analytical expressions of the diversity order, OP and DOR in the high signal-to-noise ratio (SNR) regime. Numerical results reveal that FAS at the reader can significantly improve the performance of BC compared with a fixed-antenna reader.