Static Context Header Compression Over 5G
draft-mokdad-schc-into-5g-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Amina MOKDAD , Laurent Toutain , Xavier Lagrange , Alexander Pelov | ||
| Last updated | 2025-07-07 | ||
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draft-mokdad-schc-into-5g-00
SCHC Working Group A. Mokdad
Internet-Draft L. Toutain
Intended status: Standards Track X. Lagrange
Expires: 8 January 2026 A. Pelov
IMT Atlantique
7 July 2025
Static Context Header Compression Over 5G
draft-mokdad-schc-into-5g-00
Abstract
This document describes a possible integration of Static Context
Header Compression [RFC8724] into 5G networks.
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This Internet-Draft will expire on 8 January 2026.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. 5G Architecture . . . . . . . . . . . . . . . . . . . . . . . 2
3. SCHC over 5G . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. SCHC Placement in 5G . . . . . . . . . . . . . . . . . . 3
3.2. SCHC Capability Signaling . . . . . . . . . . . . . . . . 4
3.3. SCHC Context Identification . . . . . . . . . . . . . . . 6
3.4. SCHC Packet Handling . . . . . . . . . . . . . . . . . . 7
4. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
This document defines a solution for how Static Context Header
Compression and fragmentation (SCHC) can be used in 5G. It proposes
a new architecture that integrates SCHC within the 5G core network.
This architecture can handle both full-IP flows and SCHC flows while
ensuring compatibility with full-IP application servers, based on
3GPP specifications. The document also describes the SCHC parameters
needed to support SCHC over the 5G architecture. (to be done)
2. 5G Architecture
+--------+ +--------+
| AUSF |-------------------| UDM |
+--------+ +--------+
\ / |
\ / |
\ / |
+-------------+ +-------------+
| AMF |-------| SMF |
+-------------+ +-------------+
/ | |
/ | |
/ | |
+-----+ +-----+ +-------+ +----------------+
| UE |-------| gNB |------------| UPF |-----------| Data Network |
+-----+ +-----+ +-------+ +----------------+
Figure 1: 3GPP 5G Core Architecture simplified
The 5G network architecture is illustrated in Figure 1 . Below is a
brief explanation of the main components
The 5G system consists of the following main components
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* User Equipment (UE) It includes all devices that can connect to 5G
networks, such as smartphones, IoT devices, etc.
* Radio Access Network (RAN) It consists of new radio technologies
responsible for wireless communication between the UE and the 5G
core network. One of its main components is:
gNodeB (gNB) It represents the 5G node base station.
* 5G Core Network (5GC) It is a service-based architecture that
comprises various network functions (NFs). These include:
- AMF — Manages registration, authentication, and mobility.
- SMF — Handles PDU session establishment and IP address
assignment.
- UPF — Routes and forwards user packets between UE and DN.
- UDM — Manages user identity and authorization.
- AUSF — Authenticates UE and manages key materials.
3. SCHC over 5G
3.1. SCHC Placement in 5G
+--------+ +--------+ +--------+
| NSSF | | AUSF |-----| UDM |
+--------+ +--------+ +--------+
\ | / |
\ | / |
\ | / |
+-------------+ +-------------+
| AMF |-------| SMF |
+-------------+ +-------------+
/ | |
/ | |
/ | |
+----------+ +-----+ +-------+ +----------------+
| UE |----| gNB |------------| UPF |-----------| Data Network |
| SCHC C/D | +-----+ +-------+ +----------------+
+----------+ |
+----------+
| SCHC C/D |
+----------+
Figure 2: 5G Architecture with SCHC Integration Points
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The proposed solution is depicted in Figure 2. A modified User Plane
Function (UPF), designated as SCHC-UPF and referred to as S-UPF, is
introduced. The UPF is a key component of the 5G core network,
responsible for routing and forwarding user data packets between the
User Equipment (UE) and the Data Network (DN). The S-UPF handls SCHC
compression and decompression processes. It is capable of
redirecting packets from devices that support SCHC to the SCHC
compression/decompression (C/D) unit.
+-----------+ +-----------+
| IP/Non-IP | | IP/Non-IP |
| (SCHC) | | (SCHC) |
+-----------+ +-----------+-----------+ +-----------+
| SDAP | | SDAP | GTP-U | | GTP-U |
+-----------+ +-----------+-----------+ +-----------+
| PDCP | | PDCP | UDP | | UDP |
+-----------+ +-----------+-----------+ +-----------+
| RLC | | RLC | IP | | IP |
+-----------+ +-----------+-----------+ +-----------+
| MAC | | MAC | L2 | | L2 |
+-----------+ +-----------+-----------+ +-----------+
| L1 | | PHY | L1 | | L1 |
+-----------+ <------> +-----------+-----------+ <------> +-----------+
UE gNB UPF
Radio Link N3
Figure 3: SCHC Integration in 5G User Plane Stack
3.2. SCHC Capability Signaling
This subsection describes how endpoints can signal SCHC support
during setup.
* During Registration procedure
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+-----+ +-----+ +-----+
| UE | | gNB | | AMF |
+--+--+ +--+--+ +--+--+
| | |
| Registration Request | |
| (5GMM Capability [SCHC]) | |
|============================>| |
| | |
| Selects AMF |
| | |
| | Registration Request |
| | (5GMM Capability [SCHC]) |
| |==========================>|
| | |
| | |
| Registration Accept |
| (5GS network feature support [SCHC]) |
|<========================================================|
| | |
| Registration Complete |
|========================================================>|
| | |
Figure 4: SCHC Capability Signaling During 5G Registration
* During PDU Session establishment procedure
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+-----+ +-----+ +-----+ +-----+ +------+
| UE | | gNB | | AMF | | SMF | | S-UPF|
+--+--+ +--+--+ +--+--+ +--+--+ +--+---+
| | | | |
| PDU Session Establishment Request | |
| (5GSM Core Network Capability [SCHC]) | |
|==================================================>| |
| | | | |
| | | Selects S-UPF and |
| | | IP address |
| | | | |
| | | |N4 Session Establishment|
| | | | Request |
| | | |----------------------->|
| | | |N4 Session Establishment|
| | | | Response (TEID_UPF) |
| | | |<-----------------------|
| | | | |
| PDU Session Establishment Accept | |
| (5GSM Network feature support [SCHC]) | |
|<==================================================| |
| | | | |
| | N2 PDU Session | | |
| | Resourse setup | | |
| | response | | |
| |------------------->| | |
| | |Nsmf_PDUSession_ | |
| | | UpdateSMContext | |
| | | Request | |
| | |---------------->| |
| | | | N4 Session Modification|
| | | | Request |
| | | |----------------------->|
| | | | |
| | | | |
| | | | |
<-----------><------------------ Packet data flow ------------------------->
Figure 5: SCHC Capability During PDU Session Establishment
3.3. SCHC Context Identification
The SCHC C/D unit stores the contexts of many devices connected to
the network. When a packet arrives, it must be recognized by the
SCHC C/D in order to retrieve the appropriate device context.
Therefore, the use of a unique identifier is essential. Among 5G
identifiers, there is the Permanent Equipment Identifier (PEI), which
identifies UEs capable of accessing a 3GPP network. What makes the
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PEI suitable for this use is that it is known by both the 5G operator
and the device owner, and it is transmitted to the UPF during the
PFCP association procedure.
3.4. SCHC Packet Handling
This subsection presents how the S-UPF handle SCHC-compressed
packets.
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+-----+ +----- +--------+ +----+
| UE |---->| gNB | ---------> | S-UPF | -----------------> | DN |
+-----+ +-----+ +--------+ \ +----+
\ / /\ \---------------------------------\
\ / / \ \
+--------------------+/ +----------------------------------------\----------------------------+
| IP | | +---------------------+ \ |
| src: gNB addr | | | PFCP Session Look | \ |
| dest: UPF addr | | | Retrieve UE ID | \ |
+--------------------+ | +---------------------+ \ |
| UDP | | +---------------------------+ \ |
| Port number | | | Retrieve the UE identifier| +--------------------+ |
+--------------------+ | +---------------------------+ | IP | |
| GTP | | | +--------------------+ |
| TEID 2 | | +---------------------------+ | UDP | |
+--------------------+ | | SCHC D | +--------------------+ |
| SCHC Packet | | | Decompress using UE ID | | Payload | |
| +-------------+ | | | and find context |----> +--------------------+ |
| | Rule ID | | | +---------------------------+ |
| |-------------| | | \ / |
| | Residue | | | \ / |
| +-------------+ | | +--------------------+ |
+--------------------+ | | IP | |
| | src: gNB addr | |
| | dest: UPF addr | |
| +--------------------+ |
| | UDP | |
| | Port number | |
| +--------------------+ |
| | GTP | |
| | TEID 2 | |
| +--------------------+ |
| | +-------------+ | |
| | | IP | | |
| | +-------------+ | |
| | | UDP | | |
| | +-------------+ | |
| | | Payload | | |
| | +-------------+ | |
| +--------------------+ |
+---------------------------------------------------------------------+
Figure 6: Uplink Data Decompression at S-UPF
4. Normative References
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[RFC8724] Minaburo, A., Toutain, L., Gomez, C., Barthel, D., and JC.
Zuniga, "SCHC: Generic Framework for Static Context Header
Compression and Fragmentation", RFC 8724,
DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/rfc/rfc8724>.
Authors' Addresses
Amina Mokdad
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie
35576 Cesson-Sevigne Cedex
France
Email: amina.mokdad@imt-atlantique.fr
Laurent Toutain
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie
35576 Cesson-Sevigne Cedex
France
Email: laurent.toutain@imt-atlantique.fr
Xavier Lagrange
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie
35576 Cesson-Sevigne Cedex
France
Email: xavier.lagrange@imt-atlantique.fr
Alexander Pelov
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie
35576 Cesson-Sevigne Cedex
France
Email: alexander.pelov@imt-atlantique.fr
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