# RF-EMF Exposure near 5G NR Small Cells
## 1 Introduction  
An important innovative aspect of the latest generation of cellular networks (i.e., the fifth generation, or 5G) is the widespread deployment of low-powered base stations (referred to as densification), known under the umbrella term'small cells'. Small cells are expected to be mounted lower on the infrastructure and with a higher density in order to provide a significant increase in network capacity where it is needed, such as in dense urban environments, sports venues, and shopping malls. As such, both workers (e.g., for utility companies) and members of the general public are more likely to reside in close proximity to these sources of radiofrequency (RF) electromagnetic fields (EMFs). Regarding the size and technical specifications of small cells, there is no consensus between the various standardization and legislative bodies. For example, for the 3G Partnership Project (3 GPP), a base station is a small cell when \"the antenna is sited above the median but below the maximum height of the surrounding roof tops\" [1]. However, a categorization scheme for base stations based on the equivalent isotropic radiated power (EIRP) was developed by the International Electrotechnical Commission (IEC) [2] and adopted in European Union (EU) legislation [3], found in Table 1. IEC base station classes E100, E10, and E2 fall under the general definition of a small cell. Small cells may contain a small number of antenna elements to permit up to four spatial layers (i.e., maximum 4 \(\times\) 4 multiple-input-multiple-output (MIMO)) transmitted sector-wide (i.e., with an opening angle of 120\({}^{\circ}\)), or they may comprise Advanced Antenna Systems (AAS), which contain antenna arrays of a large number of antenna elements (up to hundreds) and provide massive MIMO and beamforming capabilities. However, base stations with an Advanced Antenna System (AAS) are not considered in this E-class categorization scheme. Therefore, in [3], for outdoor AAS with massive multiple-input-multiple-output (MaMIMO) beamforming antennas, an upper limit of 30 dBm (or 1 W) transmit power was suggested instead of the guidelines of Table 1 (which are kept for traditional passive antennas). In situ measurements of RF-EMF exposure levels near small cells have been performed previously in [4; 5] (3G indoors), [6] (2G indoors), [7] (mixed 2G-4G, mixed indoors/outdoors, broadband measurements), and [8] (4G outdoors). The studied small cells featured passive antennas. In addition, maximum power densities at close distances (down to 1 m) of 5G small cells operating at 28 GHz (with AAS) were simulated in [9] for several transmission powers and antenna gains. Furthermore, in situ measurement methodologies for 5G new radio (NR) signals have been presented in, e.g., [2; 10; 11; 12; 13] for frequencies below 6 GHz (NR Frequency Range (FR) 1) and in, e.g., [14; 15; 16] for frequencies above 24 GHz (NR FR2, also called millimeter waves or mmWaves). This study delivers the first assessment of both worst-case (extrapolated and measured) as well as typical RF-EMF exposure levels near 5G NR small cells, using the measurement methodology developed previously in [10] and adopted by the IEC [2]. The results of this work can be used by, e.g., electric utilities (i.e., companies in the electric power industry) who are considering placing 5G small cells on poles or other utility infrastructures in neighborhoods. First, the measurement equipment and methods are outlined, followed by a description of the base station sites. Then, typical exposure use cases are introduced, which, along with the extreme use cases with maximum exposures, result in a range of potential exposures induced by 5G NR small cells in the population based on the measurements. Finally, the exposure levels were compared to the reference levels in the guidelines issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [17].