Outage Performance Analysis for Mutualistic Symbiotic Backscatter Communication Systems

In this paper, the considered mutualistic symbiotic backscatter communication system comprises a base station (BS), a receiver (R) and multiple spatially randomized tags positioned within a circular area centered around R. In each transmission, BS transmits the information to R, while one selected tag also conveys its own information to R by modulating and backscattering the BS's signals simultaneously. The communications from BS to R and tags to R are called as the cellular and backscatter communication (BackCom) transmissions, respectively. To describe the randomness of the position and number of the tags, the homogeneous Poisson point process is used. Besides, the consumed power by tags is considered and the optimal dynamic reflection coefficient is adopted. To achieve the tag access, the random selection access (RSA) scheme and selection diversity access (SDA) scheme are proposed and the corresponding outage performances are analyzed for both the cellular and BackCom transmissions. Numerical results show that the SDA scheme has a significantly superior outage performance compared to the RSA one at the cost of a higher system overhead. If neglecting the randomness of the number and position of tags, the obtained results will obviously deviate the practical performance. Moreover, the performance of the fixed RC scheme is much lower than that of the optimal dynamic RC.