ITU-R recommendation IMT-2020-SAT.SPECS from ITU-R WP 4B to be based on 3GPP 5G NR-NTN and IoT-NTN (from Release 17 & 18)
Backgrounder:
Non-terrestrial networks (NTN) are networks or segments of networks that use either Uncrewed Aircraft Systems (UAS) operating typically between 8 and 50km altitudes, including High Altitude Platforms (HAPs) or satellites in different constellations to carry a transmission equipment relay node or a base station:
- LEO (Low Earth Orbit): Circular orbit in altitudes of typ. 500-2.000km (lower delay and better link budget but larger number of satellites needed for coverage)
- MEO (Medium Earth Orbit): Circular orbit in altitudes of typ. 8.000-20.000km
- GEO (Geostationary Earth Orbit): Circular orbit 35.786 km above the Earth’s equator (Note: Due to gravitational forces a GEO satellite is still moving within a range of a few km around its nominal orbital position).
- HEO (Highly Elliptical Orbiting): Elliptical orbit around the earth.
Figure 1: Illustration of the classes of orbits of satellites [source: TR 22.822]
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Future ITU-R NTN standard – Recommendation ITU-R M.[IMT-2020-SAT.SPECS]:
ITU-R SG04 Circular 134 invited proposal submissions for candidate radio interface technologies for the satellite component of the radio interface(s) for IMT-2020 (ITU-R M.2150 recommendation) and invitation to participate in their subsequent evaluation. Acting on behalf of 3GPP (which it is a member of), ATIS recently submitted three 3GPP documents to ITU-R WP’s 5B and 5D for consideration. The submitted material consists of 3GPP Releases 17 and 18 and it is provided in the following documents:
1. 3GPP 5G-NTN: RIT
o NR-NTN
2. 3GPP 5G-NTN: SRIT
o Component RIT: NR-NTN
o Component RIT: IoT-NTN
Legend:
NTN=Non Terrestrial Network
RIT: Radio Interface Technology
SRIT: Set of Radio Interface Technologies
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3GPP looks forward to the continuous collaboration with ITU-R WP 4B for the finalization of Recommendation ITU-R M.[IMT-2020-SAT.SPECS], which will be the official standard for 5G satellite to ground communications.
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Release 17:
- Foundation for 5G NTN: Established the foundation for integrating 5G with non-terrestrial networks (NTNs), enabling satellite connectivity for 5G services.
- Focus on Transparent Architecture: Rel-17 NTN was based on a transparent (bent-pipe) architecture, where the satellite acts as a radio repeater, limiting payload complexity and enabling early deployment.
- Initial Standardization: 3GPP pursued a range of solutions for 5G non-terrestrial networking (NTN) based on options for the type of non-terrestrial platform and the use cases supported.
- IoT-NTN: Introduced IoT-NTN, enabling satellite connectivity for Internet of Things devices.
- Frequency Bands: Focused on L-band and S-band in FR1 for NTN.
- Foundation for 5G NTN: Established the foundation for integrating 5G with non-terrestrial networks (NTNs), enabling satellite connectivity for 5G services.
- NTN-IoT Enhancements: Further optimized NTN for IoT, including enhancements for Machine-Type Communication (MTC).
- New Service and Traffic Models: Introduced new service and traffic models to better support NTN applications.
- New Frequency Bands: Expanded frequency support to include Frequency Range 2 (FR2), spanning 17,300 MHz to 30,000 MHz.
- Focus on Ka-band: Prioritized the use of Ka-band for NR NTN deployment.
- Uplink Coverage and Mobility Enhancements: Improved uplink coverage and mobility/service continuity between NTN and terrestrial networks (NTN-TN) and between NTN networks (NTN-NTN).
- Network Verified UE Location: Enabled the network to verify UE location as per regulatory requirements.
- RedCap Enhancements: RedCap solutions were further optimized to reduce device cost and power consumption.
- Support for Store & Forward (S&F) operation based on regenerative payload: Release 18 and beyond will support Store & Forward operation based on regenerative payload, including the support of feeder link switchover.
Update:
The applicable satellite Recommendation is now ITU-R M.2177-0 (February 2026), Detailed specifications of the satellite radio interfaces of IMT-2020. It identifies the “3GPP 5G-NTN: RIT” and “3GPP 5G-NTN: SRIT” as the IMT-2020 satellite radio interfaces. The Recommendation explicitly covers NR-NTN and IoT-NTN and points to 3GPP global core specifications rather than reproducing the full 3GPP technical corpus.
References:
2 ATIS contributions to ITU-R WP 5D and 5B (only available to ITU TIES account members)
https://www.3gpp.org/technologies/ntn-overview
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4 thoughts on “ITU-R recommendation IMT-2020-SAT.SPECS from ITU-R WP 4B to be based on 3GPP 5G NR-NTN and IoT-NTN (from Release 17 & 18)”
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ITU-R has commenced the process of developing ITU-R Recommendations for the satellite component of the IMT-2020 radio interface(s).
This work is guided by Resolution ITU-R 65. This web page has been established to facilitate the development of proposals for the satellite component of the radio interface(s) for IMT-2020 and their subsequent evaluation.
Background on the satellite component of IMT-2020 (Doc. IMT-2020-SAT/1)
Requirements, evaluation criteria and submission templates for the development of IMT-2020-Satellite
Vision, requirements and evaluation guidelines for satellite radio interface(s) of IMT-2020
Report ITU-R M.2514
Evaluation Groups
ATIS Evaluation Group
European Telecommunications Standards Institute (ETSI)
5G India Forum (5GIF)
SatComForum
Interim Evaluation Reports
Document 4B/15 (SatComForum)
Document 4B/22 (ETSI)
Document 4B/23 (ATIS)
Document 4B/26 (5GIF)
https://www.itu.int/en/ITU-R/study-groups/rsg4/Pages/imt-2020-sat-submission-eval.aspx
It’s fascinating to learn about Non-terrestrial networks (NTN) and the different orbit types like LEO, MEO, GEO, and HEO. The idea of utilizing satellites in various constellations for communication relay nodes is intriguing. Have
ITU-R Working Party 4B (WP4B) will be standardizing 5G Non-Terrestrial Networks (NTN) by evaluating 3GPP technologies for inclusion in the IMT-2020 (5G) standards. The technical specifications are largely driven by 3GPP Releases 17 and 18, with ITU-R providing the regulatory recognition and finalizing the inclusion of satellite radio interfaces for 5G.
WP4B studies performance, air interfaces, and satellite radio interface technologies for the satellite component of IMT-2020, collaborating closely with 3GPP. WP4B has already acknowledged the “completeness” of 3GPP 5G NTN technology submissions, confirming their adherence to ITU-R evaluation methodologies
ITU-R WP 4B treatment of 3GPP NTN specs:
WP 4B does not edit, amend, or “correct” 3GPP technical specifications. It evaluates a submitted 3GPP NTN Radio Interface Technology (RIT) or Set of RITs (SRIT) against ITU-R satellite-IMT requirements, then develops an ITU-R Recommendation that identifies and references the applicable 3GPP specifications.
Separation of responsibilities
Body Role
3GPP Creates, maintains, and changes the normative NR-NTN, IoT-NTN, 5G Core, RAN, protocol, RF, and conformance specifications.
ITU-R WP 4B Establishes satellite-IMT requirements and evaluation methodology; evaluates candidate RIT/SRIT submissions; determines whether the proposed technology meets the requirements; and drafts the ITU-R satellite-IMT Recommendation.
ITU-R SG 4 Approves the WP 4B draft through the ITU-R Recommendation approval process.
Thus, WP 4B may determine that a submitted 3GPP technology does not yet demonstrate compliance with a required characteristic, lacks needed documentation, or must be evaluated further. It can communicate observations, requests for clarification, or technical concerns to 3GPP through formal liaison mechanisms. But it cannot make a change to a 3GPP TS or TR; only 3GPP’s relevant Technical Specification Groups and Working Groups can approve that change.
What WP 4B can change
WP 4B can change the ITU-R layer, including:
The ITU-R satellite-IMT vision, performance requirements, and evaluation criteria.
The scope, conditions, and presentation of a candidate RIT/SRIT in an ITU-R Recommendation.
Which 3GPP Global Core Specification versions, features, bands, or profiles are referenced as the basis of the recognized satellite radio interface.
Supplementary ITU-R material on system characteristics, satellite service performance, availability, spectrum compatibility, and earth-station matters.
For example, Recommendation ITU-R M.2177 recognizes the 3GPP 5G-NTN RIT and SRIT, but it does so by referencing externally maintained 3GPP specifications. The normative details remain under 3GPP version control.
Practical consequence for Release 19
If WP 4B concludes that a Release 19 NTN capability—say, regenerative payload operation or an IoT-NTN enhancement—does not meet a satellite-IMT requirement as submitted, it may withhold its recognition of that capability or request additional evaluation evidence. It may also recommend that 3GPP address a gap.
But the result would be one of these outcomes, not a WP 4B rewrite of the specification:
3GPP revises the relevant Release 19 or later specification through its ordinary change-request process, then resubmits or provides an updated reference.
WP 4B recognizes a narrower profile of the 3GPP submission that has demonstrated compliance.
WP 4B defers inclusion of the feature until supporting specification and evaluation material are mature.
WP 4B updates M.2177 to reference an approved later 3GPP specification version after the feature has been accepted.
“Rubber stamp” is therefore too strong, because there is an independent ITU-R evaluation and consensus step. But “specification modification” is also inaccurate: WP 4B evaluates and references 3GPP work; it does not exercise change control over it.
Source: Perplexity.ai