Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> F. Reduction of Human EMF Exposure <s> The increasing demand for data and multimedia services, as well as the ubiquitous nature of the current generation of mobile devices have resulted in continuous network upgrades to support an ever-increasing number of users. However, given that wireless communication systems operate on radiofrequency waves, the health effects of electromagnetic (EM) emission from these systems are increasingly becoming a concern. In order to address these concerns, we propose in this paper, an EM emission reduction scheme for the uplink of OFDM wireless systems with base station coordination. We formulate the EM reduction scheme as a convex optimization problem and solve it by iteratively allocating bits to users on their respective subcarriers in each sector. This is based on the assumption that the scheduler can predict the channel state information of all the users for a given transmission window. Simulation results show that, with coordination, our proposed scheme reduces EM emission by over 85% and 99% when compared with a no frequency reuse scheme and an energy efficiency based scheme, respectively. <s> BIB001 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> F. Reduction of Human EMF Exposure <s> The rapid growth of wireless technology worldwide has prompted interest in the underutilized millimeter-wave band from 30 to 100 GHz. Regulation agencies set limits on the amount of electromagnetic radiation absorbed by users, measuring dosimetric quantities such as specific absorption rate (SAR) to assess compliance. The increased rate of energy deposition in human tissue at high frequencies remains a growing concern as wireless cellular networks begin to incorporate millimeter wave technologies. In this paper, we present a baseband model for SAR-aware wireless communication and a strategy for optimal hybrid precoding in millimeter wave systems with SAR constraints. <s> BIB002 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> F. Reduction of Human EMF Exposure <s> Massive multiple-input multiple-output (MIMO) is a fundamental enabler to provide high data throughput in next generation cellular networks. By equipping the base stations (BSs) with tens or hundreds of antenna elements, narrow and high gain beams can be used to spatially multiplex several user equipment (UE) devices. While increasing the achievable performance, focusing the transmit power into specific UE directions also poses new issues when performing the radio frequency (RF) exposure assessment. In fact, the spatial distribution of the actual BS transmit power strongly depends on the deployment scenario and on the position of the UEs. Traditional methods for assessing the RF exposure compliance boundaries around BS sites are generally based on maximum transmit power and static beams. In massive MIMO systems, these approaches tend to be very conservative, in particular when time averaging is properly considered. In this work, we propose to leverage the three dimensional spatial channel model standardized by the Third Generation Partnership Project in order to assess reasonably foreseeable compliance boundaries of massive MIMO BSs. The analysis is performed by considering BSs fully loaded and different configurations of active UEs per cell. Numerical results show that the statistical approach developed in this paper allows reducing to nearly half the compliance distance when compared to the traditional method. <s> BIB003 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> F. Reduction of Human EMF Exposure <s> The application of wireless body area network (WBAN) in health sector is crucial. It prolongs the life expectancy and improves the quality of life by enabling remote health monitoring. Despite many advantages, it may result and exacerbates various extant health issues especially in the context of mobile multimedia. Due to high data rate of mobile multimedia applications, heat generated from sensor devices is considerably high and results in thermal dissipation. The thermal impact of sensors on human body has largely been a neglected topic. The paper rigorously analyzes the specific absorption rate (SAR) impact on human body. Moreover, the paper largely contributes by comprehensively evaluating SAR impact under various circumstances and dependency factors. The analysis and evaluation show promising results that can significantly help the successful design and deployment of WBAN strategies. The paper also provides great guidance to numerous practitioners of this domain. <s> BIB004
Albeit not many, schemes for EMF emission reduction in a wireless system have been proposed in recent literature. Examples include channel precoding BIB002 and transmit power control BIB001 . Note that the human exposure can be reduced if a base station (BS) adopts a power control or adaptive beamforming technique BIB003 . Also, the exposure level can be reduced when multiple spectrum bands are combined for coordinated use. The reason is that with a higher carrier frequency, a wireless system should reduce the cell size, which leads to more severe threats to human health. Another latest study discovered that the position of the sink is also an important parameter for SAR BIB004 .