In the fifth-generation and beyond era, reconfigurable intelligent surface (RIS) and dynamic metasurface antennas (DMAs) are emerging metamaterials keeping up with the demand for high-quality wireless communication services, which promote the diversification of portable wireless terminals. However, along with the rapid expansion of wireless devices, the electromagnetic (EM) radiation increases unceasingly and inevitably affects public health, which requires a limited exposure level in the transmission design. To reduce the EM radiation and preserve the quality of communication service, we investigate the spectral efficiency (SE) maximization with EM constraints for uplink transmission in hybrid RIS and DMA assisted multiuser multiple-input multiple-output systems. Specifically, alternating optimization is adopted to optimize the transmit covariance, RIS phase shift, and DMA weight matrices. We first figure out the water-filling solutions of transmit covariance matrices with given RIS and DMA parameters. Then, the RIS phase shift matrix is optimized via the weighted minimum mean square error, block coordinate descent and minorization-maximization methods. Furthermore, we solve the unconstrainted DMA weight matrix optimization problem in closed form and then design the DMA weight matrix to approach this performance under DMA constraints. Numerical results confirm the effectiveness of the EM aware SE maximization transmission scheme over the conventional baselines.
翻译:在第五代和以后的时代,可重新整合的智能表面和动态表面天线(DMAs)正在出现符合高质量无线通信服务需求的元材料,这种服务能够促进便携式无线终端的多样化,然而,随着无线装置的迅速扩展,电磁辐射会不断加剧,不可避免地影响公共健康,这要求在传输设计中的接触量有限。为了减少EM辐射并保持通信服务的质量,我们调查了光谱效率的最大化,同时对混合的IRIS和DMA协助的多用户多输出多输出传输系统传输的电联传输限制。具体而言,采用了交替优化,以优化传输可变性、TRIS阶段转移和DMA重量矩阵矩阵的快速扩展。我们首先用给TRIS和DMA参数来找出传输常态矩阵的充水解决方案。然后,通过加权最低正方差差、块协调下位和微化的离子化转换方法优化了频谱效率。此外,我们还在SIMA的不控制下,在SIMA模型设计下,在SIMA的封闭式标准下,对DIMA级测试模型测试模型测试模型的不连续性测试结果。