As a recently proposed idea for future wireless systems, intelligent
reflecting surface (IRS) can assist communications between entities which do
not have high-quality direct channels in between. Specifically, an IRS
comprises many low-cost passive elements, each of which reflects the incident
signal by incurring a phase change so that the reflected signals add coherently
at the receiver. In this paper, for an IRS-aided wireless network, we study the
problem of power control at the base station (BS) for physical-layer
broadcasting under quality of service (QoS) constraints at mobile users, by
jointly designing the transmit beamforming at the BS and the phase shifts of
the IRS units. Furthermore, we derive a lower bound of the minimum transmit
power at the BS to present the performance bound for optimization methods.
Simulation results show that, the transmit power at the BS approaches the lower
bound with the increase of the number of IRS units, and is much lower than that
of the communication system without IRS.

本文提出了一种基于智能反射面的无线网络，研究了在 QoS 约束下，通过联合设计基站的发射波束和 IRS 元件的相位调节进行物理层广播的功率控制问题，并导出了用于优化方法的性能下界。仿真结果表明，随着 IRS 单元数量的增加，基站的发射功率接近下限，并且比没有使用 IRS 的通信系统的发射功率低得多。