Joint Beamforming for RIS-Assisted Integrated Communication, Sensing and Power Transfer Systems
Yue Yang, Hui Gao, Xiaoyu Yang, Ruohan Cao, Yongjian Fan
Abstract
This letter studies a reconfigurable intelligent surface (RIS)-aided integrated communication, sensing and power transfer systems. We aim to maximize the received energy from the energy harvester by jointly optimizing the (active) transmit beamforming at the BS and (passive) reflect beamforming by the phase shift of the RIS, subject to the Cramér-Rao bound for the target, the received signal-to-noise ratio (SNR) at the information decoding receiver and the transmit power constraint at the BS. To solve this non-convex problem with coupled variables, we decouple it into two subproblems and introduce an alternating optimization framework. The transmit beamforming sub-problem is recast into a convex form using the Schur complement and semidefinite relaxation techniques. Subsequently, auxiliary variables are introduced to transform the phase shift sub-problem into a convex problem. Simulation results show that the proposed algorithm can significantly improve the received energy while ensuring communication and sensing performance.