STAR-RIS Assisted Wireless Communication using WOA

Abstract

We study emerging wireless technologies like RIS and STAR-RIS and the advan tages of STAR-RIS over RIS. We propose a Spatially STAR-RIS-assisted communica tion system and compare the spectral efficiency with different operating modes under various SNR conditions. The proposed system employs two different modes of opera tion, namely Energy Splitting (ES), and Mode Switching (MS). MS is a particular case of ES where each element of MS can either transmit or reflect while in ES each element of the STAR-RIS can simultaneously transmit and reflect. Whale optimization algo rithm(WOA) is a swarm optimization technique applied for optimizing the amplitude and phase coefficients of the transmission and reflection coefficient matrix of STAR RIS. The simulation results conclude that ES mode performs better than MS mode. Acheivable sum rate increases with number of RIS elements. The ergodic sum rate accurately matches with the closed form sum rate which proves the our mathematical model is correct. WOA converges for less than 10 iterations for N=32.