Physical Channel Modeling for RIS-Empowered Wireless Networks in Sub-6 GHz Bands : (Invited Paper)

Kilinc, Fatih; Yildirim, Ibrahim; Başar, Ertuğrul

doi:10.1109/ieeeconf53345.2021.9723295

Cited by 20 publications

(22 citation statements)

References 10 publications

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“…In addition, fair comparisons have been made between relays and RISs based on signal-to-interference-noise ratio (SINR) maximization for different scenarios such as varying pathloss models and RIS positionings [20]. Furthermore, RIS channel models have been investigated thoroughly for different scenarios such as indoor and outdoor applications and their benefits have been emphasized [21,22].…”

Section: Introductionmentioning

confidence: 99%

Over‐the‐air equalization with reconfigurable intelligent surfaces

et al. 2022

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Reconfigurable intelligent surface (RIS)-empowered communications is on the rise and is a promising technology envisioned to aid in 6G and beyond wireless communication networks. RISs can manipulate impinging waves through their electromagnetic elements enabling some sort of control over the wireless channel. The potential of RIS technology is explored to perform a sort of virtual equalization over-the-air for frequency-selective channels, whereas equalization is generally conducted at either the transmitter or receiver in conventional communication systems. Specifically, using an RIS, the frequency-selective channel from the transmitter to the RIS is transformed to a frequency-flat channel through elimination of inter-symbol interference (ISI) components at the receiver. ISI is eliminated by adjusting the phases of impinging signals particularly to maximize the incoming signal of the strongest tap. First, a general end-to-end system model is provided and a continuous to discrete-time signal model is presented. Subsequently, a probabilistic analysis for elimination of ISI terms is conducted and reinforced with computer simulations. Furthermore, a theoretical error probability analysis is performed along with computer simulations. It is analysed and demonstrated that conventional RIS phase alignment methods can successfully eliminate ISI, and the RIS-aided communication channel can be converted from frequency-selective to frequency-flat.

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Section: Introductionmentioning

confidence: 99%

Over‐the‐air equalization with reconfigurable intelligent surfaces

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“…From this point of view, a unified narrowband channel model for RIS-assisted systems both in indoor and outdoor environments is introduced in [3], [26], [27] by including the 5G mmWave channel model with a random number of clusters/scatterers and the characteristics of the RIS. Moreover, a physical channel model for RIS-assisted systems is proposed in [28] by considering the currently used technical specifications on sub-6 GHz bands.…”

Section: A General Perspective On Ris Channel Modelingmentioning

confidence: 99%

“…7. Interested readers are referred to [28] for the details channel generation procedure and statistical background of the considered channel parameters. By considering the…”

Section: Bandsmentioning

confidence: 99%

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Channel Modeling in RIS-Empowered Wireless Communications

Yıldırım¹,

Başar²

2022

Preprint

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One of the most critical aspects of enabling next-generation wireless technologies is developing an accurate and consistent channel model to be validated effectively with the help of real-world measurements. From this point of view, remarkable research has recently been conducted to model propagation channels involving the modification of the wireless propagation environment through the inclusion of reconfigurable intelligent surfaces (RISs). This study mainly aims to present a vision on channel modeling strategies for the RIS-empowered communications systems considering the state-of-the-art channel and propagation modeling efforts in the literature. Moreover, it is also desired to draw attention to open-source and standard-compliant physical channel modeling efforts to provide comprehensive insights regarding the practical use-cases of RISs in future wireless networks.

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“…The RIS controller manipulates the reflection of incident electromagnetic waves towards the desired direction by intelligently controlling the phase shift of elements [1]. The passive beamforming nature of RISs has been shown to improve network capacity [1], [2], enhance the end-to-end performance of multi-hop communications [3], and deliver a performance comparable to traditional relaying schemes [4].…”

Section: Introductionmentioning

confidence: 99%

RIS-Assisted Grant-Free NOMA

Tasci¹,

Kılınç²,

Çelik³

et al. 2022

Preprint

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This paper introduces a reconfigurable intelligent surface (RIS)-assisted grant-free non-orthogonal multiple-access (GF-NOMA) scheme. To ensure the power reception disparity required by the power domain NOMA (PD-NOMA), we propose a joint user clustering and RIS assignment/alignment approach that maximizes the network sum rate by judiciously pairing user equipments (UEs) with distinct channel gains, assigning RISs to proper clusters, and aligning RIS phase shifts to the cluster members yielding the highest cluster sum rate. Once UEs are acknowledged with the cluster index, they are allowed to access their resource blocks (RBs) at any time requiring neither further grant acquisitions from the base station (BS) nor power control as all UEs are requested to transmit at the same power. In this way, the proposed approach performs an implicit over-the-air power control with minimal control signaling between BS and UEs, which has shown to deliver up to 20% higher network sum rate than benchmark GF-NOMA and optimal grant-based PD-NOMA schemes depending on the network parameters. The given numerical results also investigate the impact of UE density, RIS deployment, and RIS hardware specifications on the overall performance of the proposed RIS-aided GF-NOMA scheme.

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Physical Channel Modeling for RIS-Empowered Wireless Networks in Sub-6 GHz Bands : (Invited Paper)

Cited by 20 publications

References 10 publications

Over‐the‐air equalization with reconfigurable intelligent surfaces

Over‐the‐air equalization with reconfigurable intelligent surfaces

Channel Modeling in RIS-Empowered Wireless Communications

RIS-Assisted Grant-Free NOMA

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