Content for TR 23.700-29 Word version: 19.0.0

1 Scope p. 12

The scope of this Technical Report is to study the following aspects of 5GS/EPS integrating of satellite component in Release 19, including:

Regenerative payload generic architecture:
- Impact to 5GS and EPS to support gNB/eNB onboard the satellite.
Store and Forward Satellite operation for delay tolerant services:
- The control plane and user plane enhancements if applicable, including the minimum necessary set of Core Network elements to be embedded in the satellite, to support S&F Satellite operation, both for IoT NTN (EPS) and NR NTN (5GS);
- The parameters needed to characterize and support S&F Satellite operation from a delay tolerant services perspective if applicable, both for IoT NTN (EPS) and NR NTN (5GS).
NOTE:
S&F for IoT NTN will be studied first and if there is remaining time available NR NTN can then be studied.
UE-Satellite-UE communication enhancements for 5GS, supporting NR NTN NGSO constellation with and without ISL, with feeder link always available:
- Following SA1 requirements, study how IMS enablers including mission critical can be supported;
- Minimum necessary set of 5GS network functions onboard the satellite(s) to support such UE-Satellite-UE communication.

2 References p. 12

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.

[1]

TR 21.905: "Vocabulary for 3GPP Specifications".

[2]

TS 23.501: "System Architecture for the 5G System; Stage 2".

[3]

TS 23.502: "Procedures for the 5G system, Stage 2".

[4]

TS 23.503: "Policy and Charging Control Framework for the 5G System".

[5]

TS 23.401: "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access".

[6]

TS 22.261: "Service requirements for the 5G system; Stage 1".

[7]

TS 23.682: "Architecture enhancements to facilitate communications with packet data networks and applications".

[8]

TR 22.865: "Study on satellite access Phase 3".

[9]

TS 23.228: "IP Multimedia Subsystem (IMS); Stage 2".

[10]

TS 29.514: "5G System; Policy Authorization Service; Stage 3".

[11]

TS 24.229: "IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3".

[12]

TS 38.413: " NG-RAN; NG application protocol (NGAP)".

[13]

TS 36.300: "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description".

[14]

TS 36.413: "Evolved Universal Terrestrial Radio Access Network (E-UTRAN); S1 Application Protocol (S1AP)".

[15]

TS 24.501: "Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3".

[16]

RFC 7976: "Updates to Private Header (P-Header) Extension Usage in Session Initiation Protocol (SIP) Requests and Responses" (https://www.rfc-editor.org/rfc/rfc7976.txt).

[17]

TS 24.301: "Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3".

[18]

TS 23.272: "Circuit Switched (CS) fallback in Evolved Packet System (EPS); Stage 2".

[19]

TS 23.040: "Technical realization of the Short Message Service (SMS)".

[20]

TS 29.338: "Diameter based protocols to support Short Message Service (SMS) capable Mobile Management Entities (MMEs)".

[21]

TS 23.334: "IP Multimedia Subsystem (IMS) Application Level Gateway (IMS-ALG) - IMS Access Gateway (IMS-AGW) interface: Procedures descriptions".

[22]

TS 33.501: "Security architecture and procedures for 5G System".

[23]

TS 33.401: "3GPP System Architecture Evolution (SAE); Security architecture".

[24]

TS 29.561: "5G System; Interworking between 5G Network and external Data Networks; Stage 3".

[25]

TS 29.513: "5G System; Policy and Charging Control signalling flows and QoS parameter mapping; Stage 3".

3 Definitions of terms and abbreviations p. 13

3.1 Terms p. 13

For the purposes of the present document, the terms given in TR 21.905, TS 23.401 and TS 23.501 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

Serving satellite:

a satellite providing the satellite access to a UE (e.g. providing the serving cell(s)). Depending on the orbit, the serving satellite is covering a given geographic area for a limited period of time.

S&F Satellite operation:

operation mode providing communication service (in storing and forwarding information) to a UE in periods of time and/or geographical areas in which the serving satellite is not simultaneously connected to the ground network via feeder link or ISL. For the case of UL, "store" refers to on-board storage of UL information from UE and "forward" refers to forwarding of stored UL information to the ground network. For the case of DL, "store" refers to on-board storage of DL information from the ground network and "forward" refers to forwarding of stored DL information to the UE.

UE-Satellite-UE Communication:

refers to a communication between UEs under the coverage of one or more serving satellites, using satellite access without the user traffic transiting through the ground segment.

NTN Gateway:

an earth station located at the surface of the earth, providing connectivity to the NTN payload using the feeder link. An NTN Gateway is a TNL node.

3.2 Abbreviations p. 14

For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.

ISL

Inter-Satellite Link

NTN

Non-Terrestrial Network

S&F

Store and Forward

SSF

Satellite S&F

SSFC

SSF Centre

4 Architectural Assumptions and Principles p. 14

The following architecture assumptions are applied to the study:

The 5GC architecture for satellite access for NR as defined in TS 23.501 is used as a baseline.
The EPC architecture for satellite access for IoT as defined in TS 23.401 and the architecture enhancements to facilitate communications with packet data networks and applications as defined in TS 23.682 are used as a baseline.
At least eNB/gNB is assumed to be on board the satellite.
Impacts to UE, network functions and entities are minimised. To the extent possible, existing procedures and functionality is reused.
Inter-Satellite Links (ISL) and Feeder link are assumed to act only as transport layer links and are not specified in 3GPP, and the use of ISL is assumed to have no impact on the reference points between core network entities when these core network entities are onboard.
Store and Forward Satellite Operation assumes that UE-satellite-ground network connectivity can be intermittent as defined in clause 3.1.
Store and Forward Satellite Operation shall work without ISL.
NR UE-Satellite-UE communication assumes a connection to the ground is always available.
NR UE-Satellite-UE communication assumes only IMS services including MMTEL and mission critical communications are considered.
The enhancement for NR UE-Satellite-UE communication assumes a minimum set of core network entities, including at least UPF, is present onboard of the satellites.
NR UE-Satellite-UE communication assumes that the serving satellite will be of MEO or of LEO type.
NR UE-Satellite-UE communication for MMTEL service assumes communication between two UEs under the coverage of the same satellite or different satellites.