Energy-Efficient Precoding in Electromagnetic Exposure-Constrained Uplink Multiuser MIMO

User electromagnetic (EM) exposure is continuously being exacerbated by the evolution of multi-antenna portable devices. To mitigate effects EM radiation, devices must satisfy tight regulations on user level, generally measured specific absorption rate (SAR). this end, we investigate SAR-aware uplink precoder design for energy efficiency (EE) maximization in multiuser multiple-input multiple-output transmission exploiting statistical channel state information (CSI). As objective function problem computationally demanding absence closed form, present an asymptotic approximation to facilitate design. An iterative algorithm based Dinkelbach's method and sequential optimization proposed obtain optimal solution EE problem. Based transformed problem, water-filing scheme further conceived precoding with CSI. Numerical results illustrate substantial performance improvements provided our energy-efficient over traditional baseline schemes.