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arXiv · 2302.04432

Active Simultaneously Transmitting and Reflecting (STAR)-RISs: Modelling and Analysis

Jiaqi Xu·Jiakuo Zuo·Joey Tianyi Zhou·Yuanwei Liu
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Abstract

A hardware model for active simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs) is proposed consisting of reflection-type amplifiers. The amplitude gains of the STAR element are derived for both coupled and independent phase-shift scenarios. Based on the proposed hardware model, an active STAR-RIS-aided two-user downlink communication system is investigated. Closed-form expressions are obtained for the outage probabilities of both the coupled and independent phase-shift scenarios. To obtain further insights, scaling laws and diversity orders are derived for both users. Analytical results confirm that active STAR-RIS achieves the same diversity orders as passive ones while their scaling laws are different. It is proved that average received SNRs scale with M and M^2 for active and passive STAR-RISs, respectively. Numerical results show that active STAR-RISs outperform passive STAR-RISs in terms of outage probability especially when the number of elements is small.

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Jiaqi Xu, Jiakuo Zuo, Joey Tianyi Zhou, Yuanwei Liu. 2023-02-09. Active Simultaneously Transmitting and Reflecting (STAR)-RISs: Modelling and Analysis. https://arxiv.org/abs/2302.04432

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