Enhancing Multi-Source Ambient Backscatter Communication With Transmit Power Coordination

In practical massive Internet of Things (IoT), the backscatter device (BD) in ambient backscatter communication (AmBC) systems can be illuminated by multiple ambient sources. However, multiple sources cause severe multi-source direct-link interference (M-DLI) to the BDs while providing multi-source backscattering. The signal-to-noise-plus-interference ratio (SINR) is sensitive to the transmit power of the sources. To fully benefit from multiple sources, this letter introduces transmit power coordination (TPC) strategies to suppress M-DLI and enhance backscattering by tuning the transmit power of the sources within their available ranges, which is particularly suitable for densely deployed passive BDs. To conduct the TPC strategies, the primary objective is to minimize the bit-error-rate (BER) in the multi-source AmBC system by solving a Rayleigh quotient (RQ) maximization problem. Simulation results show that the proposed TPC-assisted receive beamforming method achieves more efficient symbol detection than traditional AmBC detectors and outperforms conventional multi-antenna techniques, especially under low direct-link signal-to-noise ratio (SNR) conditions.