ETSI GR RIS 003 V1.1.1 (2023-06)

Reconfigurable Intelligent Surfaces (RIS); Communication Models, Channel Models, Channel Estimation and Evaluation Methodology

DGR/RIS-003

General Information

• Status: Not Published
• Technical Committee: RIS - Reconfigurable Intelligent Surfaces
• Current Stage: 12 - Completion
• Due Date: 10-Jul-2023
• Completion Date: 23-Jun-2023

Standards Content (Sample)

ETSI GR RIS 003 V1.1.1 (2023-06)






GROUP REPORT
Reconfigurable Intelligent Surfaces (RIS);
Communication Models, Channel Models,
Channel Estimation and Evaluation Methodology
Disclaimer
The present document has been produced and approved by the Reconfigurable Intelligent Surfaces (RIS) ETSI Industry
Specification Group (ISG) and represents the views of those members who participated in this ISG.
It does not necessarily represent the views of the entire ETSI membership.

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2 ETSI GR RIS 003 V1.1.1 (2023-06)

Reference
DGR/RIS-003
Keywords
methodology, RIS

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Contents
Intellectual Property Rights . 5
Foreword . 5
Modal verbs terminology . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definition of terms, symbols and abbreviations . 7
3.1 Terms . 7
3.2 Symbols . 7
3.3 Abbreviations . 8
4 Introduction . 9
4.1 General Description . 9
4.2 Definition of RIS . 9
4.3 Types of RIS . 9
4.4 Deployment scenarios . 10
5 Models for RIS . 11
5.1 Models for communications . 11
5.1.1 General description . 11
5.1.2 Locally periodic discrete model . 11
5.1.3 Mutually-coupled antenna model . 11
5.1.4 Inhomogeneous sheets of surface impedance . 12
5.2 Models for radio localization and sensing . 13
5.2.1 Scenarios . 13
5.2.1.1 Localization scenarios . 13
5.2.1.2 SISO localization . 13
5.2.1.3 MISO localization . 13
5.2.1.4 SIMO localization . 14
5.2.1.5 MIMO localization . 14
5.2.1.6 RIS-aided and RIS-standalone . 14
5.2.2 Near-field . 15
5.2.2.1 Near-field regimes . 15
5.2.2.2 Near-field multiple paths . 16
5.2.2.3 Near-field single-path. 17
5.2.3 Far-field . 19
5.3 Continuous and discrete models . 20
6 Channel models . 20
6.1 Objectives of channel modeling and general principles . 20
6.2 Existing channel models . 21
6.3 Path-loss models . 21
6.3.1 Description of different cases . 21
6.3.1.1 General description . 21
6.3.1.2 General case . 21
6.3.1.3 Near-field case . 22
6.3.1.4 Far-field case . 22
6.4 Empirical channel model . 23
6.5 Multipath models . 24
6.5.1 Unstructured models for rich scattering (sub-6 GHz) environments . 24
6.5.2 Structured models for rich scattering (sub-6 GHz) environments . 24
6.5.3 Structured (geometric) models for high frequency bands . 25
6.6 Multi-mode reradiation models . 25
6.7 Interference and unwanted reradiation models . 26
6.7.1 Definition of interference and unwanted reradiation . 26
6.7.1.1 General description . 26
6.7.1.2 RIS contribution to the interference propagation channel (In-Band Reradiation) . 26
ETSI

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4 ETSI GR RIS 003 V1.1.1 (2023-06)
6.7.1.3 Unwanted reradiations (Unexpected/Irregular/Discontinuously Time-Varying Out-Of-Band
Reradiation) . 27
6.7.2 Characterization of interference and unwanted reradiation . 28
6.7.2.0 General description . 28
6.7.2.1 Generated by the RIS itself . 29
6.7.2.2 Generated by other RIS . 29
6.7.2.3 Single and Multi/Inter-Operator Modeling . 29
6.7.2.4 Eavesdropping . 30
6.7.3 Destructive beamforming . 30
6.7.4 Modeling CSI mismatch due to interference and unwanted reradiation . 32
6.7.4.1 CSI mismatch due to interference (In-Band Reradiation) . 32
6.7.4.2 CSI mismatch due to Unwanted reradiations . 32
6.7.5 Spurious reradiation . 34
6.8 Polarized RIS element modeling . 35
7 Channel Estimation . 36
7.1 Reference scenarios . 36
7.1.1 General description . 36
7.1.2 RIS cannot perform on-board channel estimation . 36
7.1.3 RIS can perform on-board channel estimation . 36
7.1.4 Availability of direct link between gNB and UE . 37
7.2 Cascaded and separated channel estimation . 37
7.2.1 General description . 37
7.2.2 Methods to estimate the end-to-end cascaded channel . 37
7.2.2.0 General . 37
7.2.2.1 Element-wise RIS channel estimatio n . 38
7.2.2.1.0 General . 38
7.2.2.1.1 System model including one RIS element . 38
7.2.2.1.2 System model including all RIS elements . 39
7.2.2.1.3 Sub-surface based RIS channel estimation . 40
7.2.2.2 Configuration-wise RIS channel estimation . 40
7.2.2.3 Single RF chain enabled RIS channel estimation . 40
7.2.3 Methods to estimate the separated/individual RIS channels . 41
7.3 Estimation methods for unstructured channel models . 41
7.4 Methods for structured channel models. 42
7.5 Methods based on availability of channel state information . 42
7.6 Hybrid RIS-assisted channel estimation . 43
8 Key performance indicators and evaluation methodology . 43
8.1 Key performance indicators . 43
8.1.1 Rate/Throughput . 43
8.1.2 Spectral Efficiency . 43
8.1.3 Coverage (User Percentiles) . 44
8.1.4 Energy Efficiency . 44
8.1.5 Security . 44
8.1.6 Latency . 44
8.1.7 Reliability . 44
8.1.8 Overhead . 44
8.2 Design Parameters . 45
8.2.1 RIS size . 45
8.2.2 Electromagnetic Field Exposure . 45
8.2.3 Carrier Frequency . 45
8.2.4 Bandwidth . 45
8.3 Reference scenarios for evaluation . 45
8.4 Evaluation methodology . 49
8.4.1 Link-level evaluation . 49
8.4.2 System-level evaluation . 49
8.4.3 Link budget evaluation . 51
9 Conclusions . 58
History . 59

ETSI

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5 ETSI GR RIS 003 V1.1.1 (2023-06)
Intellectual Property Rights
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Foreword
This Group Report (GR) has been produced by ETSI Industry Specification Group (ISG) Reconfigurable Intelligent
Surfaces (RIS).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.

ETSI

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6 ETSI GR RIS 003 V1.1.1 (2023-06)
1 Scope
The present document is intended to study:
a) communication models that strike a suitable trade-off between electromagnetic accuracy and simplicity for
performance evaluation and optimization at different frequency bands;
b) channel models (deterministic and statistical) that include path-loss and multipath propagation effects, as well
as the impact of interference for application to different frequency bands;
c) channel estimation, including reference scenarios, estimation methods, and system designs; and
d) key performance indicators and the methodology for evaluating the performance of RIS for application to
wireless communications, including the coexistence between different network operators, and for fairly
comparing different transmission techniques, communication protocols, and network deployments.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] ETSI GR RIS 001 (V1.1.1): "Reconfigurable Intelligent Surfaces (RIS); Use Cases, Deployment
Scenarios and Requirements".
[i.2] ETSI TR 138 901 (V16.1.0): "5G; Study on channel model for frequencies from 0.5 to 100 GHz
(3GPP TR 38.901 version 16.1.0 Release 16)".
[i.3] Recommendation ITU-R SM.329: "Unwanted emissions in the spurious domain".
[i.4] M. Di Renzo, F. H. Danufane and S. Tretyakov: "Communication Models for Reconfigurable
Intelligent Surfaces: From Surface Electromagnetics to Wireless Networks Optimization", in
TM
Proceedings of the IEEE , 2022, doi: 10.1109/JPROC.2022.3195536.
[i.5] G. Gradoni and M. Di Renzo: "End-to-End Mutual Coupling Aware Communication Model for
Reconfigurable Intelligent Surfaces: An Electromagnetic-Compliant Approach Based on Mutual
TM
Impedances", in IEEE Wireless Communications Letters, vol. 10, no. 5, pp. 938-942, May 2021,
doi: 10.1109/LWC.2021.3050826.
[i.6] W. Tang et al.: "Wireless communications with reconfigurable intelligent surface: Path loss
TM
modeling and experimental measurement", IEEE Trans. Wireless Commun., vol. 20, no. 1,
pp. 421-439, January 2021.
[i.7] W. Tang et al.: "Path loss modeling and measurements for reconfigurable intelligent surfaces in
TM
the millimeter-wave frequency band", IEEE Transactions on Communications 70, no. 9 (2022):
6259-6276.
ETSI

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7 ETSI GR RIS 003 V1.1.1 (2023-06)
TM
[i.8] S. W. Ellingson: "Path loss in reconfigurable intelligent surface-enabled channels", 2021 IEEE
nd
32 Annual International Symposium on Personal, Indoor and Mobile Radio Communications
(PIMRC).
[i.9] F. H. Danufane et al.: "On the Path-Loss of Reconfigurable Intelligent Surfaces: An Approach
TM
Based on Green's Theorem Applied to Vector Fields," in IEEE Transactions on
Communications, vol. 69, no. 8, pp. 5573-5592, August 2021.
[i.10] Emil Björnson and Luca Sanguinetti: "Rayleigh fading modeling and channel hardening for
TM
reconfigurable intelligent surfaces", IEEE Wireless Communications Letters 10, no. 4 (2020):
830-834.
[i.11] N. S. Perović et al.: "Achievable Rate Optimization for MIMO Systems With Reconfigurable
TM
Intelligent Surfaces", in IEEE Transactions on Wireless Communications, vol. 20, no. 6,
pp. 3865-3882, June 2021.
[i.12] A. Abrardo et al.: "MIMO Interference Channels Assisted by Reconfigurable Intelligent Surfaces:
Mutual Coupling Aware Sum-Rate Optimization Based on a Mutual Impedance Channel Model",
TM
Wireless Communications Letters, vol. 10, no. 12, pp. 2624-2628, December 2021.
in IEEE
[i.13] Ibrahim Yildirim and Ertugrul Basar: "Channel Modeling in RIS‐Empowered Wireless
Communications", in Intelligent Reconfigurable Surfaces (IRS) for Prospective 6G Wireless
TM
, 2023, pp.123-148, doi: 10.1002/9781119875284.ch7.
Networks, IEEE
TM
[i.14] A. Saleh and R. Valenzuela: "A statistical model for indoor multipath propagation", in IEEE
Journal of Selected Areas in Communications, vol. 5, no. 2, pp. 128-137, February 1987.
[i.15] C. Pan et al.: "An Overview of Signal Processing Techniques for RIS/IRS-Aided Wireless
TM
Systems", in IEEE Journal of Selected Topics in Signal Processing, vol. 16, no. 5, pp. 883-917,
August 2022.
[i.16] A. Díaz-Rubio and S. A. Tretyakov: "Macroscopic Modeling of Anomalously Reflecting
TM
Metasurfaces: Angular Response and Far-Field Scattering", in IEEE Transactions on Antennas
and Propagation, vol. 69, no. 10, pp. 6560-6571, October 2021.
[i.17] V. Degli-Esposti et al.: "Reradiation and Scattering from a Reconfigurable Intelligent Surface: A
TM
General Macroscopic Model", in IEEE Transactions on Antennas and Propagation, 2022.
[i.18] B. Sihlbom, et al.: "Reconfigurable Intelligent Surfaces: Performance Assessment Through a
TM
Wireless Communications, 2022.
System-Level Simulator", in IEEE
[i.19] 3GPP TR 37.885: "Study on evaluation methodology of new Vehicle-to-Everything (V2X) use
cases for LTE and NR".
[i.20] ETSI TR 137 910: "5G; Study on self evaluation towards IMT-2
...