Sven Kuehn

The constant increase in the required user capacity and the evolution of wireless network technologies impact the exposure that users experience from wireless networks. This paper presents an evaluation of various 5G network topologies regarding human exposure, mobile communication quality, and sustainability. We evaluate human exposure, based on a novel Exposure Ratio (ER) metric, in 5G networks that include Massive Multiple-Input Multiple-Output (MaMIMO) and compare them with existing 4G deployments in three environments in Switzerland. Quality and sustainability of mobile communication is evaluated by extrapolating data rates from mobile operators to the year 2030. For designing the 5G network topologies, a multi-objective optimisation algorithm is implemented, maximising the user coverage while minimising the downlink (DL) and uplink (UL) exposure. An extensive set of simulations investigated three municipalities, three operators plus one unified network, three use cases (UL/DL data rates), three scenarios (indoor and outdoor coverage), and two optimisation methods. The study results confirm that the human exposure in a 5G network is dominated by the UL being ten times larger than the DL exposure. Furthermore, comparing a 5G deployment with 10 times the traffic capacity of a real 4G network, DL exposure increases by 36% on average and UL exposure decreases by up to 75% depending on the scenario. Regarding indoor coverage versus outdoor only, our results show that DL exposure can be reduced by a factor of 10 if only outdoor coverage is targeted. Finally, the study concludes that the ideal network, from the human exposure perspective, should use 5G MaMIMO and be optimised for both UL and DL exposure.

Fifth generation networks (5G) will be associated with a partial shift to higher carrier frequencies, including wavelengths comparable in size to insects. This may lead to higher absorption of radio frequency (RF) electromagnetic fields (EMF) by insects and could cause dielectric heating. The yellow fever mosquito (Aedes aegypti), a vector for diseases such as yellow and dengue fever, favors warm climates. Being exposed to higher frequency RF EMFs causing possible dielectric heating, could have an influence on behavior, physiology and morphology, and could be a possible factor for introduction of the species in regions where the yellow fever mosquito normally does not appear. In this study, the influence of far field RF exposure on A. aegypti was examined between 2 and 240 GHz. Using Finite Difference Time Domain (FDTD) simulations, the distribution of the electric field in and around the insect and the absorbed RF power were found for six different mosquito models (three male, three female). The 3D models were created from micro-CT scans of real mosquitoes. The dielectric properties used in the simulation were measured from a mixture of homogenized A. aegypti. For a given incident RF power, the absorption increases with increasing frequency between 2 and 90 GHz with a maximum between 90 and 240 GHz. The absorption was maximal in the region where the wavelength matches the size of the mosquito. For a same incident field strength, the power absorption by the mosquito is 16 times higher at 60 GHz than at 6 GHz. The higher absorption of RF power by future technologies can result in dielectric heating and potentially influence the biology of this mosquito.

In this study, the total electromagnetic dose, i.e., the combined dose from fixed antennas and mobile devices, was estimated for a number of hypothetical network topologies for implementation in Switzerland to support the deployment of fifth generation (5G) mobile communication systems while maintaining exposure guidelines for public safety. In this study, we consider frequency range 1 (FR1) and various user scenarios. The estimated dose in hypothetical 5G networks was extrapolated from measurements in one of the Swiss 4G networks and by means of Monte Carlo analysis. The results show that the peak dose is always dominated by an individual’s mobile phone and, in the case of non-users, by the bystanders’ mobile phones. The reduction in cell size and the separation of indoor and outdoor coverage can substantially reduce the total dose by >10 dB. The introduction of higher frequencies in 5G mobile networks, e.g., 3.6 GHz, reduces the specific absorption rate (SAR) in the entire brain by an average of −8 dB, while the SAR in the superficial tissues of the brain remains locally constant, i.e., within ±3 dB. Data from real networks with multiple-input multiple-output (MIMO) were not available; the effect of adaptive beam-forming antennas on the dose will need to be quantitatively revisited when 5G networks are fully established.

The electromagnetic exposure of cell phone users depends on several parameters. One of the most dominant of these is the distance between the cell phone and the head tissue. The pinna can be regarded as a spacer between the top of the phone and the head tissue. The size of this spacer has not yet been systematically studied. The objective of this article is to investigate the variations of distance as a function of age of the exposed person, and the mechanical force on the pinna and how it affects the peak spatial specific absorption rate (psSAR). The distances were measured for adults and children (6–8 years of age) while applying a well‐defined force on the pinna using a custom‐developed measurement device. The average distances of the pinnae to the heads and their standard deviations showed no major differences between the two age groups: 10.5 ± 2.0 mm for children (6–8 years) and 9.5 ± 2.0 mm for adults. The pinnae of our anatomical high‐resolution head models of one adult and two children were transformed according to the measurement results. The numerical exposure analysis showed that the reduced distance due to the pinna compression can increase the maximum 10 g psSAR by approximately 2 dB for adults and children, if the exposure maximum is associated with the upper part of the phone. Bioelectromagnetics 31:406–412, 2010.

Short-range wireless radio-frequency devices are rapidly pervading home and office environments. Nevertheless, their contribution to the electromagnetic field exposure of humans has not yet been systematically assessed, nor have the procedures for testing compliance been developed. In this paper, we have assessed the range of exposure in terms of the dosimetric and incident field quantities for devices of the most common technologies, i.e., digital enhanced cordless telecommunications, wireless local area networks and Bluetooth, as well as wireless communication devices based on proprietary standards in the frequency range from 30 MHz to 6 GHz. Well-defined procedures to obtain the worst case operational modes are presented. Since operation in the near-field of these devices cannot be excluded, dosimetric evaluation is the most straightforward technique for testing compliance when low-power exclusions are not applicable. The suitability of the suggested methods is demonstrated through the examination of five classes of short-range transmitters.