论文标题
分析和优化具有干扰的智能反射表面辅助系统
Analysis and Optimization of an Intelligent Reflecting Surface-assisted System with Interference
论文作者
论文摘要
在本文中，我们研究了一个智能反射表面（IRS）辅助系统，其中多元素IRS在多元素IRS的帮助下为单个Antenna的使用者提供了单个Antenna用户，在有多个Antenna BS生成的干扰下，为其自身的单人体使用者提供了干扰。通过IRS的信号和干扰链接以里奇亚语褪色进行建模。为了降低相调整成本，我们采用了准静态相移设计，在该设计中，相位移位不会随瞬时通道状态信息（CSI）而变化。我们在BSS上研究了两例CSI病例，即瞬时CSI病例和统计CSI案例，并基于完整的CSI和CSI以及分别施加最大比率传输（MRT）和视线（LOS）组件的CSI。在两个CSI案例中，频道估计和波束形成调整的成本不同。首先，我们在瞬时CSI病例中获得了平均速率的可拖动表达，并且在统计CSI病例中的千古率表达可拖动。我们还为瞬时CSI病例中的平均速率提供了足够的条件，以超过统计CSI案例中任何相位移位的厄法德率。然后，我们在相移方面最大化平均速率和千古率，导致两个非凸优化问题。对于每个问题，我们在某些系统参数下获得了全球最佳解决方案，并根据平行坐标下降（PCD）提出了一种迭代算法，以在任意系统参数下获得固定点。接下来，在每种CSI情况下，我们提供了足够的条件，与没有IRS的系统相比，最佳的准静态相移设计是有益的。最后，我们从数字上验证了分析结果，并证明了对现有解决方案的明显收益。
In this paper, we study an intelligent reflecting surface (IRS)-assisted system where a multi-antenna base station (BS) serves a single-antenna user with the help of a multi-element IRS in the presence of interference generated by a multi-antenna BS serving its own single-antenna user. The signal and interference links via the IRS are modeled with Rician fading. To reduce phase adjustment cost, we adopt quasi-static phase shift design where the phase shifts do not change with the instantaneous channel state information (CSI). We investigate two cases of CSI at the BSs, namely, the instantaneous CSI case and the statistical CSI case, and apply Maximum Ratio Transmission (MRT) based on the complete CSI and the CSI of the Line-of-sight (LoS) components, respectively. Different costs on channel estimation and beamforming adjustment are incurred in the two CSI cases. First, we obtain a tractable expression of the average rate in the instantaneous CSI case and a tractable expression of the ergodic rate in the statistical CSI case. We also provide sufficient conditions for the average rate in the instantaneous CSI case to surpass the ergodic rate in the statistical CSI case, at any phase shifts. Then, we maximize the average rate and ergodic rate, both with respect to the phase shifts, leading to two non-convex optimization problems. For each problem, we obtain a globally optimal solution under certain system parameters, and propose an iterative algorithm based on parallel coordinate descent (PCD) to obtain a stationary point under arbitrary system parameters. Next, in each CSI case, we provide sufficient conditions under which the optimal quasi-static phase shift design is beneficial, compared to the system without IRS. Finally, we numerically verify the analytical results and demonstrate notable gains of the proposal solutions over existing ones.
