Sum-Rate Maximization of Symbiotic Multi-V2X MISO and Multi-RIS BackCom with Imperfections

In this paper, we develop an optimization framework for the symbiotic operation of a primary multi-vehicle-to-everything (MV2X) communication network employing downlink communication and a secondary backscatter (BC) communication (BackCom) network of wireless-powered sensor equipped reflecting configurable surfaces (RISs), sharing the same spectrum. The secondary semi-passive RISs provide the multiple primary receivers with a spatial diversity gain and enable transmitting their own data to a designated IoT central system equipped with a BC reader. We develop an alternating optimization algorithm for resource allocation to maximize the sum-rate for mutually beneficial symbiotic radio operation. The presented simulation results demonstrate the superiority of the proposed optimization algorithm over conventional beamforming designs and fixed RIS reflection coefficient benchmarks.