# Electromagnetic Field-Aware Radio Resource Management for 5G and Beyond: A Survey
## 4 EMF Exposure Level and 5G Technologies
### EMF Exposure and 5G Radio Access Technologies
The authors reported that the most appropriate evaluation method for estimating EMF exposure was based on a statistical modeling approach. However, the authors provided no recommendations or guidelines for the suggested approach. In [31], the authors utilized their knowledge of a traffic beam pattern envelope to evaluate EMF exposure and to estimate the compliance boundary of an MIMO transmission by a 5G BS. The authors claimed that the far-field spherical formula (PD) could be used to estimate the EMF compliance boundaries accurately. However, this claim contradicts the finding of [32; 33], who claimed that PD estimation was not capable of representing the level of energy that was actually absorbed by the human body. Moreover, in [34], the authors stated that estimating the compliance boundary based on a comparison between the maximum acceptable PD set by [10] and the calculated PD (using a deterministic analysis approach) was not accurate due to the movement of the users and the connection time between the BS and the users. The authors proposed a statistical approach to overcome this issue, which depends on the normalized average power pattern (NAPP) of a planner array antenna. An 8 \(\times\) 8 MIMO antenna, which covered 120\({}^{\circ}\) on the azimuth plane and 30\({}^{\circ}\) on the vertical plane, was considered to study the compliance boundary for safety in an urban area associated with a 5G network. The authors investigated the effects of several parameters on the calculation of the NAPP. Based on the results and findings, the NAPP was majorly affected by the number of radiating antenna elements, the size of the scanning region, and the angular distribution around the element array. Beamforming technology is vital for meeting 5G networks' demands and requirements for a high data rate, improved fairness, and high reliability [35; 36]. Generally, beamforming is a technique that steers the signals generated from an array of antenna elements toward the direction of the intended UE [37]. Specifically, by utilizing beamforming technique, the signal is sent over each transmit antenna with a weighted scaling factor. Next, previous studies that evaluated EMF exposure due to the utilization of beamforming techniquesin 5G networks are reviewed. In the literature, only a few studies have focused on EMF exposure due to beamforming in 5G networks. In [27], the authors analyzed the main health risks frequently associated with specific 5G features, e.g., MIMO, beamforming, cell densification, the adoption of mmWave, and the connection of millions of devices. They suggested that the beamforming feature was key to mitigating and reducing the total power radiated by a 5G BS by concentrating the radiated power into a narrow beam directed toward the intended user. The authors in [2; 38] showed that EMF exposure from antenna arrays utilizing a beamforming technique applied with the limits defined by international regulations [31], highlighting that a simple model could be employed to estimate the exclusion zones from gNBs operating with MIMO and beamforming techniques. In [33; 39], the authors evaluated EMF exposure from a 28 GHz 5G gNB utilizing an 8 \(\times\) 8 planar array antenna with fixed beamforming in urban macro- and micro-cell environments. The proposed model assumes wide and fixed beams, ignoring the impact of pencil beams that are positioned toward individual users. According to the authors, the SAR measurement metric was more effective than PD in evaluating the impacts of mobile signals on human health, as the SAR reflected the level of energy that was actually absorbed by the human body. Hence, the authors used both the PD and SAR metrics to evaluate the impacts of the fixed beamforming technique with a wide beam width on the EMF exposure level. For PD evaluation, an approach similar to the one proposed in [40] was used with a fixed beam width of 65 degrees.