论文标题
通过强大的IRS元素激活，IRS辅助通信系统中能源效率的全球优化
Global Optimization of Energy Efficiency in IRS-Aided Communication Systems via Robust IRS-Element Activation
论文作者
论文摘要
在本文中，我们在不完美的通道状态信息（CSI）下研究了使用单恒定发射器和接收器的智能反射表面（IRS）辅助通信系统。更具体地说，我们处理IRS元素的二元二进制（开/关）状态的强大选择，以最大程度地提高最坏情况的能源效率（EE）（EE），并且给定有限的CSI不确定性，同时满足最小信噪比（SNR）。调整了IRS相移，以便仅基于估计的通道最大化理想的SNR（即没有CSI误差）。首先，我们得出了最坏情况下的SNR的封闭形式表达，然后制定了鲁棒（离散的）优化问题。此外，我们设计和分析了一种动态编程（DP）算法，从理论上讲，该算法可以通过多项式复杂性$ O（l \ log l）$来实现全局最大值，其中$ l $是IRS元素的数量。最后，数值模拟证实了理论结果。特别是，所提出的算法在详尽的搜索中显示出相同的性能，并且明显优于基线方案，即所有IRS元素的激活。
In this paper, we study an intelligent reflecting surface (IRS) assisted communication system with single-antenna transmitter and receiver, under imperfect channel state information (CSI). More specifically, we deal with the robust selection of binary (on/off) states of the IRS elements in order to maximize the worst-case energy efficiency (EE), given a bounded CSI uncertainty, while satisfying a minimum signal-to-noise ratio (SNR). The IRS phase shifts are adjusted so as to maximize the ideal SNR (i.e., without CSI error), based only on the estimated channels. First, we derive a closed-form expression of the worst-case SNR, and then formulate the robust (discrete) optimization problem. Moreover, we design and analyze a dynamic programming (DP) algorithm that is theoretically guaranteed to achieve the global maximum with polynomial complexity $O(L \log L)$, where $L$ is the number of IRS elements. Finally, numerical simulations confirm the theoretical results. In particular, the proposed algorithm shows identical performance with the exhaustive search, and significantly outperforms a baseline scheme, namely, the activation of all IRS elements.
