论文标题
在智能反射表面辅助无线通信中使用不完美的CSI中利用振幅控制
Exploiting Amplitude Control in Intelligent Reflecting Surface Aided Wireless Communication with Imperfect CSI
论文作者
论文摘要
智能反射表面（IRS）是一种有希望的新范式，可通过通过被动反射重新配置无线信号传播来实现未来无线网络的高光谱和能源效率。为了获得IRS的潜在收益，渠道状态信息（CSI）至关重要，而由于渠道培训资源有限，渠道估计错误在实践中是不可避免的。在本文中，为了优化IRS辅助多源系统具有不完美CSI的性能，我们建议在IRS的接入点（AP）和无源反射系数上共同设计主动传输预编码，每个编码不仅由常规相移以及纽约型的振幅变化。首先，假设使用实用的IRS通道估计方法，则可以得出每个用户的可实现率，该方法表明，由于CSI错误引起的干扰与AP传输预编码器，通道训练功率和IRS反射系数在渠道训练和数据传输过程中相关。然后，对于单用户案例，通过结合惩罚方法的益处，Dinkelbach方法和块连续的上限最小化方法（BSUM）方法，提出了一种新的受惩罚性的Dinkelbach-bsum算法，以优化IRS的反射系数，以最大程度地提高可实现的数据传输速率，以最大程度地提高到CSI错误的可实现数据传输速率；对于Multiuser情况，提出了新的罚款双重分解（PDD）算法，以最大程度地提高用户的加权总和。给出了仿真结果，以验证与基准方案相比，我们提出的算法的有效性。特别是，有用的见解是为了表征IRS反射振幅控制（/不使用常规相移）对不完美CSI下系统性能的影响。
Intelligent reflecting surface (IRS) is a promising new paradigm to achieve high spectral and energy efficiency for future wireless networks by reconfiguring the wireless signal propagation via passive reflection. To reap the potential gains of IRS, channel state information (CSI) is essential, whereas channel estimation errors are inevitable in practice due to limited channel training resources. In this paper, in order to optimize the performance of IRS-aided multiuser systems with imperfect CSI, we propose to jointly design the active transmit precoding at the access point (AP) and passive reflection coefficients of IRS, each consisting of not only the conventional phase shift and also the newly exploited amplitude variation. First, the achievable rate of each user is derived assuming a practical IRS channel estimation method, which shows that the interference due to CSI errors is intricately related to the AP transmit precoders, the channel training power and the IRS reflection coefficients during both channel training and data transmission. Then, for the single-user case, by combining the benefits of the penalty method, Dinkelbach method and block successive upper-bound minimization (BSUM) method, a new penalized Dinkelbach-BSUM algorithm is proposed to optimize the IRS reflection coefficients for maximizing the achievable data transmission rate subjected to CSI errors; while for the multiuser case, a new penalty dual decomposition (PDD)-based algorithm is proposed to maximize the users' weighted sum-rate. Simulation results are presented to validate the effectiveness of our proposed algorithms as compared to benchmark schemes. In particular, useful insights are drawn to characterize the effect of IRS reflection amplitude control (with/without the conventional phase shift) on the system performance under imperfect CSI.
