Development of Electromagnetic Field Exposure Model for Multi-Technology Mobile Networks using Optimal Weighted Antenna Angle

Abstract

Mobile networks are expanding quickly as a result of development in wireless technologies, especially with the recent introduction of the Fifth Generation New Radio (5G NR). The growth in mobile networks requires the installation of massive number of base stations (BSs) that bring concerns about increasing overall electromagnetic field (EMF) radiation exposure levels. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has published guidelines that have been adopted by many regulators in many countries to control the overall radiation from EMF transmitters. This research started with comprehensive review for recent works focused on BS EMF radiation assessment for BSs from different perspectives including review for standard limits. An enhanced formula is developed and proposed to accurately calculate the compliance distance (CD) considering more factors such as power reduction factor and system load. In situ measurements are conducted to validate the formula. The results show that CD has shorter distances when the power factor is considered. Also, the study investigated the compliance distance of shared sites by a group of Mobile Network Operators (MNO). The results shows that, compared with a single MNO, the CD increased by 41% in the case of two MNOs, 73% for three MNOs, and 100% for four MNOs. Additionally, sharing scale-up formula is driven and proposed to estimate the increase in CDs for N number of MNOs assuming that all MNOs use the same site configuration. Finally, a design model is developed and proposed to de-concentrate and reduce the total exposure ration (TER) from sectorized antennas of the multi-technology BS with no drawbacks on site coverage level and capacity. The model applies the concept of weighted antenna’s azimuth to spread the total exposure among the horizontal direction. A set of simulations and field measurements were done in a life network to validate the proposed solution. The pre-and-post results show the TER and CD are reduced after applying the proposed model. Overall, the system records show no significant impacts were observed on site’s coverage level and capacity.