Intelligent Reflecting Surface-Aided Wireless Powered Hybrid Backscatter-Active Communication Networks

Wireless powered hybrid backscatter-active communications are recognized as the promising technique to provide the sustainable communication service for wireless devices. In this paper, we consider an intelligent reflecting surface-aided wireless powered hybrid backscatter-active communication network, where multiple sensors devices powered by a power beacon, transmit their information to an access point through backscatter and active communications. In particular, an intelligent reflecting surface is properly deployed to improve the communication quality between sensor devices and access point by utilizing the composite channel gain and phase beamforming gain. Furthermore, we formulate a system energy efficiency maximization problem under the minimum throughput requirements of sensor devices, to jointly optimize the phase shifts of intelligent reflecting surface, time allocation for backscatter communications and active transmissions, and transmit power of sensor devices and power beacon. To solve the formulated non-convex problem, we first unveil the optimal phase shifts of intelligent reflecting surface, and then utilize the variable substitutions and Dinkelbach-based method to develop an iterative method to solve the energy efficiency maximization problem. Simulation results reveal that the proposed method outperforms the existing several benchmark methods in terms of system energy efficiency.