A Survey on EMF-Aware Mobile Network Planning

Considering electromagnetic field (EMF) exposure from the radio frequency (RF) domain has always been critical in deploying new cellular network technologies. European countries implement strict limits to ensure that a radiating element such as a cellular antenna cannot exceed a certain threshold in the vicinity of urban or densely populated areas. Before 5G, these limits could easily be managed with calculation methods during the network planning phase, i.e., before the physical installation of antennas. These previous-generation transmitters act statically, and it is usually simple to respect EMF limit values while ensuring adequate quality performance for end-users. Current active antenna systems benefit from Massive MIMO (Multiple Input, Multiple Output) technologies with Time Division Duplex (TDD) and precise beamforming. These technologies employed by 5G enable antennas to behave dynamically in time and space, depending on the distribution of users and the applications targeted. This new dynamic behaviour, together with larger antenna arrays, makes the estimation of RF-EMF exposure more complex, usually leading to overestimations. The only solution to lower this exposure and to make an installation compliant is to lower the output power, which potentially limits the performance of current 5G networks. In the future, as new frequencies and multiple deployment points emerge, this exposure overestimation, associated to strict regulations, could drastically restrict or even prevent the deployment of communication technologies (5G Advanced, 6G). This survey provides an overview of this broad area, looking at the global and European regulatory frameworks and then taking the case of Luxembourg, which has lower limits than most EU countries. It then references the main EMF exposure estimation methods available in the literature applied for 4G and prior generations before focusing on potential and not yet standardised approaches for 5G. The perspective is then changed to discuss the issues related to network planning and the interest in using optimisation approaches. Finally, the survey concludes by summarising the gaps and opportunities related to EMF-aware network planning solutions.