论文标题
RIS辅助毫米波DM通信系统的奇异率可实现的速度最大化
Ergodic Achievable Rate Maximization of RIS-assisted Millimeter-Wave MIMO-OFDM Communication Systems
论文作者
论文摘要
近年来，可重新配置的智能表面（RIS）引起了广泛的关注。但是，大多数研究都集中在窄带和/或瞬时通道状态信息（CSI）的情况下，而使用毫米波（包括子terahertz）频谱的宽带宽度是下一代无线通信的主要趋势，并且在现有系统中可以获得统计CSI的实用性。因此，我们{考虑} RIS辅助MMWAVE多输入多输出正交频施加多路复用通信系统的可实现的可实现速率。采用广泛使用的Saleh-Valenzuela频道模型来表征MMWave通道，并且只有统计CSI可用。我们首先通过多数化理论和詹森的不平等得出了千古的可实现率的近似值。然后，提出了一种基于优化的算法，以通过共同设计基站的传输协方差矩阵和RIS的反射系数来最大化可实现的可实现速率。具体而言，发射协方差矩阵的设计被转化为功率分配问题，并通过空间频率填充水解决。 Riemannian共轭梯度算法优化了反射系数。仿真结果证实了所提出的算法的有效性。
Reconfigurable intelligent surface (RIS) has attracted extensive attention in recent years. However, most research focuses on the scenario of the narrowband and/or instantaneous channel state information (CSI), while wide bandwidth with the use of millimeter-wave (mmWave) (including sub-Terahertz) spectrum is a major trend in next-generation wireless communications, and statistical CSI is more practical to obtain in realistic systems. Thus, we {consider} the ergodic achievable rate of RIS-assisted mmWave multiple-input multiple-output orthogonal frequency division multiplexing communication systems. The widely used Saleh-Valenzuela channel model is adopted to characterize the mmWave channels and only the statistical CSI is available. We first derive the approximations of the ergodic achievable rate by means of the majorization theory and Jensen's inequality. Then, an alternating optimization based algorithm is proposed to maximize the ergodic achievable rate by jointly designing the transmit covariance matrix at the base station and the reflection coefficients at the RIS. Specifically, the design of the transmit covariance matrix is transformed into a power allocation problem and solved by spatial-frequency water-filling. The reflection coefficients are optimized by the Riemannian conjugate gradient algorithm. Simulation results corroborate the effectiveness of the proposed algorithms.
