## 3 Results  
Figure 2 shows the differences in absorbed energy in various brain regions (tissue averaged) in the human head of the Multimodal Imaging-Based Detailed Anatomical (MIDA) phantom [27], the Ella phantom [28] and the homogeneous specific anthropomorphic mannequin (SAM) phantom with virtual brain regions mapped inside [29] when exposed to generic near-field sources in the frequency range 700-3600 MHz. The results illustrate the absorption characteristics in the human head as a function of frequency. In general, the higher the frequency, the lower the penetration of electromagnetic energy into the brain due to the stronger attenuation at higher frequencies. The tissue-averaged SAR in the outermost region (grey matter) is about a factor of 6 lower at 3.6 GHz than at 700 MHz. However, the local peak SAR (0.1 g average) on the outer surface of the grey matter remains approximately the same (\(\pm 3\) dB) over all frequencies, as shown in Figure 2. The differences in attenuation also lead to changes in the exposure levels of the different brain regions. Due to the frequency-dependent \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & **Uplink** & & **MB** & **User 1** & **User 2** & **User 3** & **User 1** & **User 2** & **User 3** \\ \cline{3-10}  & **Service** & **Unit** & **/Unit** & **Units** & **Units** & **Units** & **/MB** & **/MB** & **/MB** \\ \hline \multirow{3}{*}{atomic} & cloud services, & message & 0.05 & 10 & 50 & 1000 & 0.5 & 2.5 & 50 \\  & social media & file & 50 & 1 & 5 & 100 & 50 & 250 & 5000 \\  & picture & 5 & 8 & 20 & 250 & 40 & 100 & 1250 \\  & video & 100 & 0 & 2 & 20 & 0 & 200 & 2000 \\ \hline \multirow{3}{*}{stream} & augmented, & 10 min & 1 & 0 & 6 & 24 & 0 & 6 & 24 \\  & virtual & & & & & & & & \\ \cline{1-1}  & reality & & & & & & & & \\ \cline{1-1}  & voice call & 10 min & 6 & 1 & 2 & 12 & 6 & 12 & 72 \\ \cline{1-1}  & video call & 10 min & 150 & 0 & 3 & 12 & 0 & 450 & 1800 \\ \cline{1-1}  & system & 1 h & 1 & 4 & 8 & 16 & 4 & 8 & 16 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Uplink data traffic definition for user types 1–3 (from light to heavy). Atomic transmission units are transmitted at the maximum data rate. Streaming data units are transmitted at a constant data rate for the duration of use. attenuation, the difference in the tissue-averaged SAR between the grey matter and the thalamus increases from 3-6 dB at 700 MHz to \(>\)20 dB at 3.6 GHz. Figure 2: Characteristics of peak per tissue (top) and tissue-averaged (bottom) absorption for generic head-mounted sources simulating mobile phones as a function of frequency (700–3600 MHz) in three brain regions (white matter, grey matter, and thalamus) of human head phantom—the SAM phantom designated by standardization bodies for specific absorption rate (SAR) testing [29], the anatomical MIDA phantom [27], and the Ella phantom [28]—exposed to generic sources head-mounted sources, simulating mobile phone exposure in talk mode. In each plot, the SAR is normalized to the psaSAR\({}_{\text{10g}}\) of each exposure configuration. According to IEEE C95.1, the SAR in the pinna of Ella is excluded from the averaging volume. The plots show the average and variability over all source positions for SAM in blue, the variability for Ella in red, and for MIDA in yellow. Histograms, as shown in Figure 3, were generated for the following study variables: location: rural, suburban, urban; bystander (dependent on the population density of the location); indoor coverage: 0-100%; daily usage: 0-10 GByte/d; and cell size (edge signal reduction by 0 dB, 6 dB, or 12 dB). Median and 95 th percentile statistical summaries were then calculated to evaluate the differential effect of the study variables on the total dose. The 95 th percentile is particularly interesting, as precautionary and safety limits are designed to limit the highest exposures. We therefore present only the 95 th percentile values in the tables below and make reference to the median results in the text where necessary.