  Wireless sensing and wireless energy are enablers to pave the way for smart
transportation and a greener future. In this paper, an intelligent reflecting
surface (IRS) assisted integrated sensing and wireless power transfer (ISWPT)
system is investigated, where the transmitter in transportation infrastructure
networks sends signals to sense multiple targets and simultaneously to multiple
energy harvesting devices (EHDs) to power them. In light of the performance
tradeoff between energy harvesting and sensing, we propose to jointly optimize
the system performance via optimizing the beamforming and IRS phase shift.
However, the coupling of optimization variables makes the formulated problem
non-convex. Thus, an alternative optimization approach is introduced and based
on which two algorithms are proposed to solve the problem. Specifically, the
first one involves a semi-definite program technique, while the second one
features a low-complexity optimization algorithm based on successive convex
approximation and majorization minimization. Our simulation results validate
the proposed algorithms and demonstrate the advantages of using IRS to assist
wireless power transfer in ISWPT systems.
