Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> B. Concern on EMF Exposure <s> As wearable devices become more ingrained in our daily lives, traditional communication networks primarily designed for human-being-oriented applications are facing tremendous challenges. The forthcoming fifth-generation (5G) wireless systems look to support unprecedented high capacity, low latency, and massive connectivity. In this article, we examine key challenges facing wearable communication devices. A cloud/edge communication architecture that integrates the cloud radio access network (CRAN), software-defined network (SDN), device-to-device (D2D) communications, and cloud/edge technologies is presented. Computation offloading enabled by this multilayer communications architecture can offload computation-excessive and latency-stringent applications to nearby devices through D2D communications or to nearby edge nodes through cellular or other wireless technologies. Critical issues faced by wearable communications, e.g., short battery life, limited computing capability, and stringent latency, can be greatly alleviated by this cloud/edge architecture. Together with the presented architecture, current transmission and networking technologies [including nonorthogonal multiple access (NOMA), mobile edge computing (MCE), and energy harvesting] can greatly enhance the performance of wearable communications in terms of spectral efficiency, energy efficiency, latency, and connectivity. <s> BIB001 </s> Human Electromagnetic Field Exposure in Wearable Communications: A Review <s> B. Concern on EMF Exposure <s> Numerous antenna design approaches for wearable applications have been investigated in the literature. As on-body wearable communications become more ingrained in our daily activities, the necessity to investigate the impacts of these networks burgeons as a major requirement. In this study, we investigate the human electromagnetic field (EMF) exposure effect from on-body wearable devices at 2.4 GHz and 60 GHz, and compare the results to illustrate how the technology evolution to higher frequencies from wearable communications can impact our health. Our results suggest the average specific absorption rate (SAR) at 60 GHz can exceed the regulatory guidelines within a certain separation distance between a wearable device and the human skin surface. To the best of authors' knowledge, this is the first work that explicitly compares the human EMF exposure at different operating frequencies for on-body wearable communications, which provides a direct roadmap in design of wearable devices to be deployed in the Internet of Battlefield Things (IoBT). <s> BIB002
While mostly focusing on techniques and applications only, the literature of wearable communications is scarce in regards to human EMF exposure. Mainly due to the nature of its operation on physical contact on a human body, the wearable communications pose particular attention in the literature. As such, recent research has shown interest in the impact of SAR on the human body. More than 240 scientists who have published research on electromagnetic radiation safety believe that current national and international guidelines for exposure to radio frequency radiation are inadequate to protect human health [29] . For instance, a latest study compared the EMF exposure amounts in different spectrum bands BIB002 . The 2.4 GHz band was studied as a key spectrum band in which current wearable devices operate. Also, the study compares the SAR to that measured at 60 GHz, acknowledging that "higher-rate" Wi-Fi standards (i.e., IEEE 802.11ad and ay) operating in this band are enablers of the next-version wearable communications BIB001 . It was found that the SAR at 60 GHz can exceed the regulatory guidelines within a certain separation distance between a wearable device and the human skin surface-i.e., 12 to 15 mm BIB002 .