Passive Relaying Game For Wireless Powered Internet Of Things In Backscatter-Aided Hybrid Radio Networks

In this paper, we consider wireless powered Internet of Things (IoT) by a power beacon station (PBS). Each IoT device can be a sensor node that has continuous data transmission using a dual-mode radio, which operates in either active radio frequency (RF) communications or passive backscatter communications. The flexibility in the radio mode switching provides an additional degree of freedom to improve the overall network performance. To exploit the radio's diversity gain, we formulate the sum throughput maximization by jointly optimizing the transmission strategy of each node, the time allocation, and beamforming strategies of the PBS. Besides, capitalizing the fact that two nodes in different modes can complement each other, we propose the passive relaying scheme to exploit the user's cooperation gain that leverages the passive radios to relay for active RF communications. Though the backscatter-aided throughput maximization is nonconvex due to the coupling among different nodes, we design the passive relaying game to balance energy harvesting and relay performance. The simulation results verify that it can significantly enhance the sum throughput of a hybrid radio network, along with the optimal time allocation and beamforming strategies at the PBS.