Performance Analysis of RIS-aided MISO Systems with EMI and Channel Aging
Taoyu Song, Enyu Shi, Yu Lu, Yiyang Zhu, Jiayi Zhang, Bo Ai
TL;DR
This work analyzes a RIS-aided MISO system under electromagnetic interference (EMI) and channel aging, with a Rician BS–RIS link and Rayleigh UE–BS/UE–RIS links. It derives a closed-form downlink spectral efficiency $R_k$ under maximum ratio transmission (MRT) using MMSE channel estimation and a use-and-forget capacity bound, and validates the results via Monte Carlo simulations. Key findings show that increasing the LoS weight in the Rician BS–RIS channel boosts SE, EMI has a detrimental impact, large RIS size $M$ can be counterproductive under EMI, and RIS can offset channel aging to some extent; enlarging RIS area yields substantial gains. The study provides insights into RIS deployment under EMI and aging, and suggests EMI-aware precoding as a future direction to further mitigate interference.
Abstract
In this paper, we investigate a reconfigurable intelligent surface (RIS)-aided multiple-input single-output (MISO) system in the presence of electromagnetic interference (EMI) and channel aging with a Rician fading channel model between the base station (BS) and user equipment (UE). Specifically, we derive the closed-form expression for downlink spectral efficiency (SE) with maximum ratio transmission (MRT) precoding. The Monte-Carlo simulation supports the theoretical results, demonstrating that amplifying the weight of the line-of-sight (LoS) component in Rician fading channels can boost SE, while EMI has a detrimental impact. Furthermore, continuously increasing the number of RIS elements is not an optimal choice when EMI exists. Nonetheless, RIS can be deployed to compensate for SE degradation caused by channel aging effects. Finally, enlarging the RIS elements size can significantly improve system performance.