Abstract
An intelligent reflecting surface (IRS) is invoked for enhancing the energy harvesting performance of a simultaneous wireless information and power transfer (SWIPT) aided system. Specifically, an IRS-assisted SWIPT system is considered, where a multi-antenna aided base station (BS) communicates with several multi-antenna assisted information receivers (IRs), while guaranteeing the energy harvesting requirement of the energy receivers (ERs). To maximize the weighted sum rate (WSR) of IRs, the transmit precoding (TPC) matrices of the BS and passive phase shift matrix of the IRS should be jointly optimized. To tackle this challenging optimization problem, we first adopt the classic block coordinate descent (BCD) algorithm for decoupling the original optimization problem into several subproblems and alternately optimize the TPC matrices and the phase shift matrix. For each subproblem, we provide a low-complexity iterative algorithm, which is guaranteed to converge to the Karush-Kuhn-Tucker (KKT) point of each subproblem. The BCD algorithm is rigorously proved to converge to the KKT point of the original problem. We also conceive a feasibility checking method to study its feasibility. Our extensive simulation results confirm that employing IRSs in SWIPT beneficially enhances the system performance and the proposed BCD algorithm converges rapidly, which is appealing for practical applications.
Highlights
R ECENTLY, intelligent reflecting surface (IRS)-assisted wireless communication has received considerable research attention, since it is capable of supporting costeffective and energy-efficient high data rate communication for next-generation communication systems [1]–[3]
We considered an IRS-assisted multicell multiple-input multiple-output (MIMO) communications scenario [24], where we demonstrated that deploying an IRS at the cell edge is capable of mitigating the adjacentcell interference
The path loss exponents of the base station (BS)-IRS, IRS-energy receivers (ERs), IRS-information receivers (IRs), BS-IR and BS-ER links are respectively set as αBSIRS = 2.2, αIRSER = 2.2, αIRSIR = 2.4, αBSIR = 3.6 and αBSER = 3.6
Summary
R ECENTLY, intelligent reflecting surface (IRS)-assisted wireless communication has received considerable research attention, since it is capable of supporting costeffective and energy-efficient high data rate communication for next-generation communication systems [1]–[3]. An IRS is composed of a vast number of low-cost and passive reflective components, each of which is capable of imposing a phase change on the signals incident upon them. In contrast to conventional physical layer techniques that are designed for accommodating the hostile time-varying wireless channels [5], [6], IRSs constitute a new paradigm capable of ‘reprogramming’ the wireless propagation environment into a more favorable transmission medium. Since the reflective components are passive, they impose a much lower power consumption than conventional relay-aided communication systems relying on active transmission devices. No thermal noise is imposed by the IRS, since it directly reflects the incident signals without decoding or amplifying them, which is in contrast to conventional relays. The optimization variables are coupled and the joint design leads to a complex optimization problem that is difficult to solve
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