On the Exposure Dose Minimization of Multi-Antenna Multi-Carrier System Users

Abstract

From the fourth generation (4G) of cellular systems onward, wireless personal devices (WPDs) support multi-input multi-output (MIMO) communication. However, the impact of MIMO communication on the electromagnetic field (EMF) of WPD users has yet to be fully understood and analyzed at the system level. In this paper, we first provide a generic model for assessing the individual exposure dose of multi-antenna WPD users in a multi-user multi-carrier communication system. An optimization framework for minimizing this exposure dose is then developed based on our exposure model. This framework helps us to identify a new criterion, i.e., the ratio between the normalized exposure dose and the channel to noise ratio (CNR), as the main system level criterion for minimizing the individual exposure dose of multi-antenna WPD users. This criterion is further integrated in the design of two novel centralized resource allocation schemes that take advantage of the multiple antennas at the WPD to minimize the per-user exposure dose, when full or limited knowledge of each user channel is available. Our new schemes can significantly reduce the individual exposure dose of WPD users (by approximately 80%) in comparison with the most relevant existing resource allocation schemes. Our results also provide insights into the logarithmic relationship between the per-user exposure dose and the number of receive antennas (or the number of time slots), and how such a parameter can be exploited to further reduce the exposure and/or provide a higher SE while maintaining a low exposure dose.

Optimal phase shift design for fair allocation in RIS aided uplink network using statistical CSI

“…They propose an optimization strategy to select the RIS phases to minimize the EMF exposure in terms of the exposure index while maintaining a minimum target QoS for the users. The authors of [29] propose an optimization strategy to minimize the average exposure dose of users, considering both the system's QoS and transmit power constraints. Given that our resource allocation scheme maximizes the minimum user SINR, we must ensure that the resulting solution will not result in users experiencing more EMF radiation than the stipulated thresholds.…”

Rate-Splitting Multiple Access for Uplink Massive MIMO With Electromagnetic Exposure Constraints

“…In uplink transmissions, EM exposure is measured by a standard metric named specific absorption rate (SAR), which indicates the EM power absorbed by human tissue per unit mass [3]. Compared with the constraint on power, which is only related to the amplitudes of multiple antennas, SAR is also the function of phase differences between any two transmit signals [7], [8]. The SAR model is based on experimental studies, which can be characterized by the sinusoidal function of the phase difference [9].…”