An optimized scheme for energy efficient wireless communication via intelligent reflecting surfaces

Abstract

Intelligent reflecting surfaces (IRSs) are considered as a promising candidate enabling technology for future green wireless communication. Such intelligent surfaces have real-time reconfigurable properties that beamform the signal to a desired destination. In this paper, our objective is to study the performance optimization in an IRS-assisted wireless network. An array of reflecting elements is individually configured in IRS system set up, which is installed between the source and the destination to assist the communication between both without any obstacle. IRS-assisted network achieves significant performance gain as compared to wireless networks without IRS. However, there are severe practical challenges with IRSs including hardware impairments, size of IRS, and distribution of reflecting elements in the IRS. To tackle these issues, we analyzed the performance of the network for maximum achievable rates, minimum transmit power, and maximum energy efficiency (EE). The selection of optimal number of reflecting elements in the IRS enables huge savings in energy to achieve target rate with minimal power. We show that by incorporating optimal number of reflecting elements in IRSs, high EE can be achieved, which outperforms the direct transmission method. Moreover, we show the impact of increasing the number of reflecting elements on the trade-off between EE and achievable rates.