Challenges in Design of Power-amplifying Active Metasurfaces

Lončar, Josip; Šipuš, Zvonimir

doi:10.1109/elmar49956.2020.9219017

Cited by 12 publications

(5 citation statements)

References 30 publications

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“…Active RIS can further amplify the reflected signals, in contrast to passive RIS which merely reflect incident signals. Active RIS, in contrast to passive RIS, has a different hardware architecture [38]. Phase shift circuits and reflection-type amplifiers are used to boost the signal strength in an active RIS.…”

Section: B Active Rismentioning

confidence: 99%

A Survey on STAR-RIS: Use Cases, Recent Advances, and Future Research Challenges

Ahmed

Wahid

Laique

et al. 2023

IEEE Internet Things J.

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The recent development of metasurfaces, which may enable several use cases by modifying the propagation environment, is anticipated to have a substantial effect on the performance of 6G wireless communications. Metasurface elements can produce essentially passive sub-wavelength scattering to enable a smart radio environment. STAR-RIS, which refers to reconfigurable intelligent surfaces (RIS) that can transmit and reflect concurrently (STAR), is gaining popularity. In contrast to the widely studied RIS, which can only reflect the wireless signal and serve users on the same side as the transmitter, the STAR-RIS can both reflect and refract (transmit), enabling 360-degree wireless coverage, thus serving users on both sides of the transmitter. This paper presents a comprehensive review of the STAR-RIS, with a focus on the most recent schemes for diverse use cases in 6G networks, resource allocation, and performance evaluation. We begin by laying the foundation for RIS (passive, active, STAR-RIS), and then discuss the STAR-RIS protocols, advantages, and applications. In addition, we categorize the approaches within the domain of use scenarios, which includes increasing coverage, enhancing physical layer security (PLS), maximizing sum rate, improving energy efficiency (EE), and reducing interference. Next, we will discuss the various strategies for resource allocation and measures for performance evaluation. We aimed to elaborate, compare, and evaluate the literature in terms of setup, channel characteristics, methodology, and objectives. In conclusion, we examine the open research problems and potential future prospects in this field.

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Section: B Active Rismentioning

confidence: 99%

A Survey on STAR-RIS: Use Cases, Recent Advances, and Future Research Challenges

Ahmed

Wahid

Laique

et al. 2023

IEEE Internet Things J.

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“…Such a matrix takes into account the coupling through the slots, the travelling through transmission lines, the amplification in the active circuits, and so forth. A similar approach was used in [38] to perform an analysis on the challenges related to power-amplifying metasurfaces, including stability issues. Other types of metasurfaces exist, including transmissive ones, and plenty of methods exist for the modelling thereof.…”

Section: Candidate Metasurfaces For Passive Blinking Jammingmentioning

confidence: 99%

Metasurfaces and Blinking Jamming: Convergent Study, Comparative Analysis, and Challenges

Mello

2023

Micromachines

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Blinking jamming is an active self-screening technique performed by at least two aircraft to tackle monopulse radars and all complexity related thereto. Nowadays, the technique can be performed with digital radiofrequency memories (DRFMs), which are cumbersome, complex, expensive, need a dedicated compartment and antenna, and introduce spurs in the signals. In this paper, we propose an alternative to the implementation of blinking jamming with DRFMs, namely with reconfigurable metasurfaces. By covering the aircraft parts that most contribute to the radar cross-section (RCS), reconfigurable metasurfaces can interchangeably absorb or amplify impinging waves, making the aircraft ‘blink’ from the radar perspective. To validate the feasibility, simulations accounting for realistic phenomena are conducted. It is seen that, if the aircraft RCS can be varied in a ratio of 10:1, either with absorptive or power-amplifying metasurfaces, a performance similar to that of the DRFM is achieved. Furthermore, a ratio of 2:1 is sufficient to make the radar antenna system movements exceed the angular range of the formation. We also anticipate our work to be a starting point for completely new ways of countering radars, e.g., with countless small drones performing passive or active stand-off blinking jamming.

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“…Moreover, to ensure that the active IRS operates at the signalamplification mode, we should properly deploy the IRS such that it satisfies η ≥ 1 [11].…”

Section: A Active Irsmentioning

confidence: 99%

“…IRS comprises a number of active reflecting elements, which are equipped with negative resistance components such as tunnel diode and negative impedance converter, thus enabled to reflect the incident signal with power amplification [11]. Note that different from the conventional amplify-and-forward (AF) relay that requires power-hungry radio frequency (RF) chains and orthogonal time/frequency resources to receive and transmit signals with power amplification, the active IRS directly reflects signals in an FD manner with low-power reflection-type amplifiers.…”

Section: Introductionmentioning

confidence: 99%

Wireless Communication Aided by Intelligent Reflecting Surface: Active or Passive?

You¹,

Zhang²

2021

Preprint

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In this letter, we consider an intelligent reflecting surface (IRS)-aided wireless communication system, where an active or passive IRS is employed to assist the communication between an access point and a user. First, we consider the downlink/uplink communication separately and optimize the IRS placement for rate maximization with an active or passive IRS. We show that the active IRS should be deployed closer to the receiver with the IRS's decreasing amplification power; while in contrast, the passive IRS should be deployed near either the transmitter or receiver. Moreover, with optimized IRS placement, the passive IRS is shown to outperform its active counterpart when the number of reflecting elements is sufficiently large and/or the active-IRS amplification power is too small. Next, we optimize the IRS placement for both active and passive IRSs to maximize the weighted sum-rate of uplink and downlink communications. We show that in this case, the passive IRS is more likely to achieve superior rate performance. This is because the optimal active-IRS placement needs to balance the rate performance in the uplink and downlink, while deploying the passive IRS near the transmitter or receiver is optimal regardless of the uplink or downlink.

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Challenges in Design of Power-amplifying Active Metasurfaces

Cited by 12 publications

References 30 publications

A Survey on STAR-RIS: Use Cases, Recent Advances, and Future Research Challenges

A Survey on STAR-RIS: Use Cases, Recent Advances, and Future Research Challenges

Metasurfaces and Blinking Jamming: Convergent Study, Comparative Analysis, and Challenges

Wireless Communication Aided by Intelligent Reflecting Surface: Active or Passive?

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