# RF-EMF Exposure near 5G NR Small Cells
## 4 Discussion and Conclusions  
This paper describes radiofrequency (RF) electromagnetic field (EMF) measurements in the vicinity of two 5G new radio (NR) base stations, both transmitting in the 5G NR n78 band (3.4-3.8 GHz), scaling the results to small-cell base station powers and the extrapolation of the obtained field levels to different exposure cases. The measurements themselves consisted of evaluating the worst-case field levels as well as measuring the time-averaged field level without any induced downlink traffic load and when maximizing the downlink traffic load (from the base station to the user device), at positions at various distances from the base stations, following IEC 62232 [2]. Then, in order to evaluate the exposures potentially induced by 5G NR small-cell base stations, the results were scaled to base station radio transmit powers maximally used by small cells [2,3]. Furthermore, these measurements were used to calculate the exposure levels for a typical user (making a video call) and a non-user in a mature network. Scaled to small-cell powers, the measured exposure levels in this study were below the MPE limits for both occupational (at distances between 0.5 m and 1 m from the base station) and general public exposure (>1 m) issued by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [17]: the maximum exposure ratios were 0.15 (occupational) and 0.68 (general public). These theoretical worst-case exposures were higher than the actual maxima measured in situ by maximizing the downlink traffic load, and both types of worst-case exposures were much higher (3-12 times) than the exposures of a typical user, which in turn were much higher (4-9 times) than the exposures without any users. Finally, the exposure of a non-user within a mature 5G NR network depends on the distribution of users, their usage, and the AAS capabilities of the base station radio. Although adverse health effects at non-thermal exposure levels cannot be ruled out [20], the ICNIRP reference levels are still relevant to calculate exposure ratios against. The measurement values obtained in this study and reported in this paper can be directly compared to other reference or limit levels (e.g., from legislation or scientific literature), depending on the scope of the study. For a 5G NR AAS base station, the actual exposure of a given user will generally be less than the theoretical maximum exposure \(E_{max}\) for several reasons. First, other users (the number may vary) may be in beams other than the one the given user is using. Hence, the RF energy directed toward these users will not add (much) to the exposure of the given user. Second, the usage by the given user will generally be less than the maximum assumed for which \(E_{max}\) was defined. Third, there may be dynamic power control to reduce base station power to the minimum needed for communication. This was not taken into account in this study. Finally, the base station beam may be narrower or wider than that used to measure \(E_{max}\). Hence, the problem of determining actual RF exposure becomes a statistical one that depends on several different variables. However, the exposure will almost always be less than \(E_{max}\). Similarly, for the non-user, the difference lies in whether they are in a beam or not. Generally, the RF exposure from the base station for the non-user will be smaller than that for a user (here by at least a factor of 5 for an AAS), unless there are many users around and the MaMIMO capabilities of the base station are limited (Table 4) [19]. The fact that the measurement results of the FSV and SRM setups are similar (Figure 3) is an important result, as it indicates that the less cumbersome SRM measurement setup performed adequately, if used in a correct way as described here, and can thus be used in future 5G NR measurement campaigns for \(E_{RE}\) (and \(E_{max}\) extrapolation, as described in [10]) and \(E_{avg}\) measurements.