The rotatable reconfigurable intelligent surface (RIS) can enhance mobile edge computing (MEC) performance by optimizing its orientation to improve the gain of received and transmitted signals. This correspondence investigates a rotatable RIS-assisted MEC system, aimed at minimizing energy consumption for multiple moving user equipment (UEs) through the joint design of RIS orientation, discrete phase shift, computation resource allocation, transmitting power and task offloading strategies. Considering the mobility of UEs, this problem is formulated as a sequential decision-making across multiple time slots. To address this challenge, a soft actor-critic (SAC)-based algorithm is proposed to optimize RIS orientation, phase shift and task offloading strategies, while computation resource allocation and transmitting power are determined based on the actions. Numerical results demonstrate that the proposed scheme exhibits superior convergence and performance compared to benchmarks. Additionally, the rotatable RIS scheme reduces total energy consumption by up to 47.3% compared to the fixed RIS, enhancing MEC system performance.

翻译：可旋转可重构智能反射面（RIS）能够通过优化其方向来改善接收与发射信号的增益，从而提升移动边缘计算（MEC）性能。本文研究了一种可旋转RIS辅助的MEC系统，旨在通过联合设计RIS方向、离散相移、计算资源分配、发射功率及任务卸载策略，为多个移动用户设备（UE）最小化能耗。考虑到UE的移动性，该问题被建模为跨多个时隙的序贯决策问题。为应对这一挑战，本文提出了一种基于软演员-评论家（SAC）的算法，用于优化RIS方向、相移及任务卸载策略，而计算资源分配与发射功率则根据所选动作确定。数值结果表明，与基准方案相比，所提方案展现出更优的收敛性与性能。此外，相较于固定式RIS，可旋转RIS方案可将总能耗降低高达47.3%，从而显著提升MEC系统性能。