RF-EMF Radiation Exposure and Radio Resources Management in 5G Wireless Network

Ajibare, Adedotun Temitope

RF-EMF Radiation Exposure and Radio Resources Management in 5G Wireless Network

Master Thesis

2022

Abstract

The fifth generation (5G) mobile network is expected to solve the challenge of heavy network traffic demand associated with mobile communication networks. Mobile communication network is characteristically heterogeneous with several base stations and numerous users with diverse demands. With the limited radio resources, there will be an infeasibility challenge in the network as the system capacity is unable to support the users' target quality of service (QoS) requirements. To bring solution to the limited resources, heavy traffic demands and congestion problems; an efficient management of resources such as; the transmit power, time, physical resource blocks (PRBs), frequency (sub-channels) is required. Deciding on how to efficiently allocate, manage, and control the resources dynamically among several slices and users in an isolated multi-tenancy scenario without compromise on the QoS/quality of experience (QoE) of user is very important. Also important is the consideration of the network challenges such as; interference (on user equipment (UE)) and radiofrequency electromagnetic field (RFEMF) radiation exposure (a health challenge on user) emitted in both the uplink and downlink of wireless networks, especially the 5G mobile network. Therefore, this research aims to assess the impacts of these challenges, develop and evaluate efficient radio resources management schemes and algorithms. Schemes that will effectively guarantee the users' QoS in terms of the data rate and reduced the interference and radiation exposure of the users in the network. Thus, this dissertation proposes four major solutions in 5G mobile networks. Firstly, a 5G network resource allocation scheme is proposed. A QoE resource allocation problem is formulated as an optimisation problem, the proposed scheme solves the problem using Mixed Integer Non-Linear Program (MINLP). It jointly incorporates admission control and a heuristic mechanism that takes the QoS constraints, the slice's and user's priorities into consideration to enhance resource utilisation efficiency, improve the throughput of users, and consequently, the QoE of users. In addition, this research also proposed a novel slicing carrier assignment scheme (SCAS), a joint power and sub-channel allocation scheme in a 5G network to reduce the co-users interference in the network. In SCAS, an optimisation problem is formulated to minimise the downlink transmit power while guaranteeing a minimum data rate requirement for the slice and user subject to QoS constraints, interference thresholds, gNB power budget and the sub-channel orthogonality constraints. The scheme assigns sub-channels to users considering the transmit power level of the neighbouring sub-channel before allocating the sub-channel to users by comparing the transmit power threshold of the slice to which the user belongs. Thirdly, this work investigates the impact of radiofrequency (RF) electromagnetic fields (EMF) radiation exposure induced by wireless networks, most importantly 5G cellular networks for both the uplink and downlink radio emissions using exposure-index open-loop power control algorithm (EOPCA), a novel simulation method that quantifies the realistic electromagnetic exposure of the human user. The exposure index (EI) is used to characterize the EMF exposure taking into account the power density, specific absorption rate (SAR), the electric field strength as well as considering other factors such as the environment, the conductivity and the mass density of the tissue. The radiations emitted from APs and UEs were simulated, analyzed and compared with the threshold set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) for the understanding of radiation impact. Lastly, this work investigates the effect of minimising the EI and SAR induced in the 5G mobile networks and its impact on the QoS of the users in the network. It proposed a power control algorithm that solves an optimisation problem formulated to minimise the EI while guaranteeing the QoS requirement of users. Given that the radiated SAR and EI are characterized by power density in the wireless network, the proposed algorithm controls the transmit and the received powers subject to interference, power and QoS constraints. The performance of the proposed schemes were evaluated and compared with standards and other algorithms in the literature. The results show that the enhanced network efficiency, improved users' QoS, reduced users' interference and reduced radiation exposure (SARs and EIs) on the users in 5G network while satisfying the required QoS in terms of the data rate. Furthermore, the results reveal that both SAR and EI are tolerable and fall within the thresholds set by the ICNIRP and other regulators.

Keywords

Electrical Engineering

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