PROJECT TITLE :

Spectrum and Energy-Efficiency Maximization in RIS-Aided IoT Networks

ABSTRACT:

It is anticipated that new device capabilities will drive the evolution of fifth-generation (5G) and beyond networks. These capabilities will support spectrum deployments and energy-efficient internet of things (IoT) deployments. Every IoT pair causes interference for one another because they compete for the same resources and operate on the same frequency spectrum. This study employs reconfigurable intelligent surfaces, or RISs, to reduce the amount of inter-node interference in an Internet of Things network using directional beamforming. This is accomplished by adjusting the phase shifts of the passive elements that make up the RIS. We take into consideration a RIS-assisted Internet of Things network that is made up of multiple pairs of IoT devices and makes use of both direct paths and reflected paths that only require one hop. The problems of spectrum-efficiency maximization (SEM) and energy-efficiency maximization (EEM) are both investigated as potential solutions to resource allocation issues. Because the nature of the formulated optimization problems is such that they are not convex, we must divide them into two sub-problems and solve them in alternating fashion. We extend the conjugate gradient technique to Riemannian manifolds in order to obtain the optimal phase shifts of the elements of the RIS for both SEM and EEM. This will allow us to obtain the optimal phase shifts. On the other hand, in order to obtain the optimal transmit power, we resolve the transmit power allocation sub-problem as a difference of concave functions for the SEM, and we use a pricing-based technique for the EEM. This allows us to obtain the optimal transmit power. The deployment of RISs to support IoT networks has been shown to be effective, according to numerical results; however, these results are qualified by the location of the RIS, the number of elements it contains, and the number of IoT node pairs. When compared to traditional, state-of-the-art networks, especially those that serve as a baseline, significant gains in energy efficiency and spectrum utilization are realized.