]> Static Context Header Compression Over 5G IMT Atlantique
CS 17607, 2 rue de la Chataigneraie Cesson-Sevigne Cedex 35576 France amina.mokdad@imt-atlantique.fr
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie Cesson-Sevigne Cedex 35576 France laurent.toutain@imt-atlantique.fr
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie Cesson-Sevigne Cedex 35576 France xavier.lagrange@imt-atlantique.fr
IMT Atlantique
CS 17607, 2 rue de la Chataigneraie Cesson-Sevigne Cedex 35576 France alexander.pelov@imt-atlantique.fr
Internet SCHC Working Group Internet-Draft This document describes a possible integration of Static Context Header Compression into 5G networks.
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)
5G Architecture
The 5G network architecture is illustrated in . Below is a brief explanation of the main components The 5G system consists of the following main components 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.
SCHC over 5G
SCHC Placement in 5G
The proposed solution is depicted in . 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.
+-----------+-----------+ <------> +-----------+ UE gNB UPF Radio Link N3 ]]>
SCHC Capability Signaling This subsection describes how endpoints can signal SCHC support during setup. During Registration procedure
| | | | | | Selects AMF | | | | | | Registration Request | | | (5GMM Capability [SCHC]) | | |==========================>| | | | | | | | Registration Accept | | (5GS network feature support [SCHC]) | |<========================================================| | | | | Registration Complete | |========================================================>| | | | ]]>
During PDU Session establishment procedure
| | | | | | | | | | 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 -------------------------> ]]>
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 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.
SCHC Packet Handling This subsection presents how the S-UPF handle SCHC-compressed packets.
| 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 | | | | | +-------------+ | | | +--------------------+ | +---------------------------------------------------------------------+ ]]>
 SCHC: Generic Framework for Static Context Header Compression and Fragmentation This document defines the Static Context Header Compression and fragmentation (SCHC) framework, which provides both a header compression mechanism and an optional fragmentation mechanism. SCHC has been designed with Low-Power Wide Area Networks (LPWANs) in mind. SCHC compression is based on a common static context stored both in the LPWAN device and in the network infrastructure side. This document defines a generic header compression mechanism and its application to compress IPv6/UDP headers. This document also specifies an optional fragmentation and reassembly mechanism. It can be used to support the IPv6 MTU requirement over the LPWAN technologies. Fragmentation is needed for IPv6 datagrams that, after SCHC compression or when such compression was not possible, still exceed the Layer 2 maximum payload size. The SCHC header compression and fragmentation mechanisms are independent of the specific LPWAN technology over which they are used. This document defines generic functionalities and offers flexibility with regard to parameter settings and mechanism choices. This document standardizes the exchange over the LPWAN between two SCHC entities. Settings and choices specific to a technology or a product are expected to be grouped into profiles, which are specified in other documents. Data models for the context and profiles are out of scope.