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

arXiv: https://arxiv.org/abs/2302.04432 · HTML: https://mlsanity.com/paper/2302.04432/

## Key facts

- Cited by 2 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 9 Feb 2023.

## Built on by (most cited first, 2 of 2)

- [QoS Improvement in Multi User Cellular-Symbiotic Radio Network Assisted by Active-STAR-RIS](https://mlsanity.com/paper/2401.08301/) (2024)
- [Active Beyond-Diagonal RIS Empowered Heterogeneous Edge Computing: A Distributional Reinforcement Learning Approach](https://mlsanity.com/paper/2607.13160/) (2026)

## Abstract (arXiv)

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.