On the reduction in specific absorption rate using uplink power adaptation in heterogeneous small-cell networks

Recent growth in wireless devices such as smart phones, tablet computers, ipads and other electronic devices made the use of radio frequency spectrum omnipresent. The widespread of wireless devices has raised health concerns due to the possible malign effects of electromagnetic radiations on the human body, and especially on the brain due to its proximity with the hand-held radio devices. These radiations are absorbed in the head while making phone calls and increase the health risks. The rate at which these radiations are absorbed in the head is referred to as specific absorption rate (SAR) and is dependent on the strength of the transmitted signals. This paper investigates a new design for future generations of wireless networks where low-power, low-cost and small-cell base stations are deployed to support the infrastructure of macrocell base stations. The resulting network is referred to as heterogeneous network (HetNet). HetNets are considered as a promising solution for situations when the mobile users have to adapt very fast their uplink transmit power over the fading channels. HetNet reduces the distance between the mobile users and the corresponding small-cell base stations. Therefore, the mobile users are no longer in need to transmit with maximum power to maintain the desired signal to interference noise ratio (SINR) and thereby the transmit power is reduced considerably especially when the mobile users are located far away form the desired base station, i.e., around the edge of the cell. Several simulations are provided to illustrate the reduction in the signal absorption rate (SAR) due to the uplink power adaptation. It is also shown that the other traditional gains such as spectral and energy efficiency of the system under consideration are significantly outperformed in comparison with the existing macrocell network.