论文标题
可主动配置智能表面的联合波束形成设计：一个亚连接的阵列结构
Joint Beamforming Designs for Active Reconfigurable Intelligent Surface: A Sub-Connected Array Architecture
论文作者
论文摘要
可重新配置的智能表面（RIS）被视为一种有前途的技术，具有促进无线网络的巨大潜力。但是，当用户与RIS不够近时，受“双重褪色”效果的影响，传统的被动RI无法带来可观的性能。最近，引入了主动RI，以通过综合反射型放大器的帮助来积极扩增事件信号来对抗双重褪色效果。为了降低由于传统完全连接的活动RI的大量活动组件而引起的硬件成本和能源消耗，最近提出了一种新颖的硬件和能量有效的亚连接的活性RIS架构，其中仅由一个机化器驱动多个可重新配置的电磁元件。在本文中，我们首先为亚连接的主动RIS体系结构开发了改进而准确的信号模型。然后，我们研究了Multiuser多输入单输出（MU-MISO）通信系统中的关节传输预编码和RIS反射波束形成（即反射相移和扩增系数）。通过利用分数编程（FP），块坐标下降（BCD），二阶锥形编程（SOCP），交替的乘数（ADMM）和多数化指导方法（Marminization-Minimization（MM-MM）方法，可以解决总和最大化和最小化问题。广泛的仿真结果验证了与常规的完全连接结构相比，提议的亚连接的主动RIS可以显着降低硬件成本和功耗，并在RIS的功率预算有限时实现良好的性能提高。
Reconfigurable intelligent surface (RIS) is regarded as a promising technology with great potential to boost wireless networks. Affected by the "double fading" effect, however, conventional passive RIS cannot bring considerable performance improvement when users are not close enough to RIS. Recently, active RIS is introduced to combat the double fading effect by actively amplifying incident signals with the aid of integrated reflection-type amplifiers. In order to reduce the hardware cost and energy consumption due to massive active components in the conventional fully-connected active RIS, a novel hardware-and-energy efficient sub-connected active RIS architecture has been proposed recently, in which multiple reconfigurable electromagnetic elements are driven by only one amplifier. In this paper, we first develop an improved and accurate signal model for the sub-connected active RIS architecture. Then, we investigate the joint transmit precoding and RIS reflection beamforming (i.e., the reflection phase-shift and amplification coefficients) designs in multiuser multiple-input single-output (MU-MISO) communication systems. Both sum-rate maximization and power minimization problems are solved by leveraging fractional programming (FP), block coordinate descent (BCD), second-order cone programming (SOCP), alternating direction method of multipliers (ADMM), and majorization-minimization (MM) methods. Extensive simulation results verify that compared with the conventional fully-connected structure, the proposed sub-connected active RIS can significantly reduce the hardware cost and power consumption, and achieve great performance improvement when power budget at RIS is limited.
