Outage Performance Analysis for Mutualistic Symbiotic Backscatter Communication Systems with Channel Estimation Errors

In the mutualistic symbiotic backscatter communications (MSBCs), backscatter devices (also called as tags), can accomplish the backscatter communication (BackCom) by reflecting the radio frequency signals from the base station (BS). Meanwhile, the backscattered signals can enhance the performance of the cellular transmission due to the reason that the signals from the backscatter link can be regarded as the useful multipath signals when decoding the cellular information. In this paper, the considered MSBC system consists of one BS, one receiver and multiple tags. To avoid the information collisions among tags, the selection diversity access (SDA) scheme is used, i.e., in each transmission, the tag that can maximize the signal-to-interference-plus-noise ratio (SINR) of the cellular transmission is selected to transmit information. The channel estimation error (CEE) is considered and the corresponding outage probabilities for both the cellular and BackCom transmissions are derived. The numerical results validate the theoretical analysis and show that the CEE has a significant impact on the system performance, which makes the diversity orders be equal to zero. Moreover, the research shows that the existence of the CEE will not affect the symbiotic relationship between the cellular and BackCom transmission.