This glossary collects the acronyms and terms that recur across the standards portal. Definitions are short and plain-language; consult the linked topic pages or the referenced specifications for full detail.
3GPP process terms
These are the process and organisational terms used throughout this section's pages (feedback, requirements, liaison statements, work-item and CR tracking) — the vocabulary of how standards get made, as distinct from the technical A-Z below.
CR (Change Request) A formal proposal to modify a published 3GPP specification. Anyone with 3GPP membership (directly or through a member company) can submit one; it is discussed and voted on in a working group before being approved, revised, or rejected.
LS (Liaison Statement) A formal letter one standards group sends to another (or that an external organisation like 5G-MAG sends to 3GPP), used to share information, ask a question, or request that a group takes an action. See Liaison Statements for 5G-MAG's incoming and outgoing statements.
pCR (pseudo-CR) A draft Change Request discussed within a group before it is formally submitted as a CR. Used to iterate on wording before something becomes official.
Rapporteur The individual (usually from a member company) responsible for driving a specific Work Item or specification through the standards process: drafting text, resolving comments, and reporting progress to the group.
Stage 1 / Stage 2 / Stage 3 3GPP's three-step specification model for a feature: Stage 1 defines the service requirements (what it should do), Stage 2 the architecture (how it fits together), and Stage 3 the detailed protocols (the exact messages and procedures an implementation must follow).
TDoc (Temporary Document)
The generic name for any document submitted to a 3GPP meeting for discussion — a CR, a pCR, an LS, a discussion paper, or a report all arrive as TDocs, numbered per group per meeting (for example R2-2506344).
TSG (Technical Specification Group) One of 3GPP's top-level groups: TSG RAN (radio access network), TSG SA (service and system aspects), TSG CT (core network and terminals). Each TSG has several working groups underneath it (for example SA4 for media codecs, CT3/CT4 for core-network protocols, RAN1/RAN2/RAN3 for physical/link/network layers).
WG (Working Group) A sub-group of a TSG that does the detailed technical work; a WG's decisions are reported up to its parent TSG plenary for approval. This portal most often references SA1 (service requirements), SA2 (architecture), SA4 (media/codecs), RAN1-3 (radio), and CT1/CT3/CT4 (core network protocols).
WI / WID (Work Item / Work Item Description) A scoped, approved piece of standardisation work: it has an owning group, a rapporteur, defined objectives, and (usually) a target release. A Work Item is what eventually produces one or more specifications or specification updates. See 3GPP Work Items per Release for how 5G-MAG tracks these per release.
PCG (Project Co-ordination Group) 3GPP's cross-body coordination group, which oversees scheduling and coordination across all the TSGs.
Plenary The full meeting of a TSG (as opposed to its working groups), where decisions from working groups are formally approved.
Agreed / Endorsed / Postponed / Withdrawn (meeting decision status) The outcomes a TDoc can reach in a meeting: agreed means adopted into the specification; endorsed means the group supports the direction but it needs further work before formal adoption; postponed means deferred to a later meeting; withdrawn means the submitter pulled it, usually because it was superseded or needs rework.
A
AF (Application Function) A network function that interacts with the 5G Core to influence traffic handling and to request services on behalf of an application.
AMF (Access and Mobility Management Function) A 5G Core function that handles UE registration, connection and mobility management, reachability, and access authentication and authorization.
ARF (Avatar Representation Format) An MPEG format for describing and exchanging avatars so that they can be rendered consistently across systems.
AS (Application Server) A server that hosts application logic or content and communicates with clients, often sitting behind or alongside 5G media functions.
B
BSF (Binding Support Function) A 5G Core function that records which PCF is handling a given UE's policy session, so that other functions (such as an NEF or AF) can discover the right PCF to contact.
C
CAMARA An open-source project community that defines common, portable network APIs so applications can use operator capabilities across networks.
CMAF (Common Media Application Format) A container format for segmented media that lets the same media segments be delivered over different streaming protocols.
D
DASH (Dynamic Adaptive Streaming over HTTP) An adaptive streaming method that splits media into segments at multiple bitrates so a client can switch quality based on conditions.
DCAF (Data Collection Application Function) A function that collects, buffers and reports application and device data for analytics and exposure to consumers.
DTLS-SRTP The combination used by WebRTC to protect media: DTLS (Datagram Transport Layer Security) negotiates and exchanges keys, which SRTP (Secure Real-time Transport Protocol) then uses to encrypt and authenticate RTP media.
E
eMBMS (evolved Multimedia Broadcast Multicast Service) The LTE-era broadcast and multicast delivery system, predecessor to 5G multicast and broadcast services.
EPC (Evolved Packet Core) The core network architecture used with LTE (4G), providing mobility management, session management and gateway functions; the predecessor to the 5G Core.
F
FeMBMS (Further evolved MBMS) Release 14 enhancements to eMBMS supporting larger-scale, single-frequency-network terrestrial broadcast, including reception without a SIM or subscription.
FLUTE (File Delivery over Unidirectional Transport) A protocol for reliably delivering files over one-way (broadcast or multicast) transport.
G
glTF (GL Transmission Format) An open format for efficient transmission and loading of 3D scenes and models.
H
HLS (HTTP Live Streaming) An adaptive streaming method that delivers media as segments over HTTP, widely used on Apple platforms.
I
ICE (Interactive Connectivity Establishment) A protocol that finds a usable network path between two peers behind NATs or firewalls, gathering and testing candidate addresses obtained via STUN and TURN.
M
MBMS (Multimedia Broadcast Multicast Service) A 3GPP framework for delivering the same content to many devices at once over broadcast or multicast bearers.
MBS (5G Multicast Broadcast Services) The 5G system feature set for delivering content to groups of devices using multicast or broadcast, rather than one stream per device.
MB-SMF (Multicast/Broadcast Session Management Function), MB-UPF (Multicast/Broadcast User Plane Function), MBSF (Multicast/Broadcast Service Function), MBSTF (Multicast/Broadcast Service Transport Function) The 5G Core functions that support MBS delivery. The MB-SMF and MB-UPF are multicast/broadcast-aware counterparts of the SMF and UPF, managing and carrying MBS sessions in the core network. The MBSF controls MBS User Services and Service Announcements on behalf of an application provider. The MBSTF handles application-layer delivery of MBS data (for example object distribution) down to the MB-UPF. These functions are linked by 3GPP-defined reference points — including N2, N3, N4, N11, N16, N19mb, N29mb, and the Nmb1/Nmb2/Nmb5/Nmb8/Nmb9/Nmb10 interfaces (see TS 23.247) — which are not each given a separate glossary entry here.
MIV (MPEG Immersive Video) An MPEG coding approach for immersive video that supports viewing from multiple positions and directions.
N
NEF (Network Exposure Function) A 5G Core function that securely exposes network capabilities and events to authorised external applications.
NPN (Non-Public Network) A 5G network deployed for the needs of a specific organisation or site rather than for the general public.
NRF (Network Repository Function) A 5G Core function that maintains a registry of available network function instances and their profiles, and supports discovery between functions.
NTN (Non-Terrestrial Network) A network that uses satellites or other airborne or spaceborne platforms to provide connectivity.
P
PCF (Policy Control Function) A 5G Core function that provides policy rules for how traffic and sessions are treated.
PTM (Point-to-Multipoint) Delivery of the same content from one source to many receivers at the same time.
PTP (Point-to-Point) Delivery of content from one source to a single receiver, one stream per device.
Q
QoD (Quality on Demand) A network capability that lets an application request a specific quality of service for a session when needed.
QoS (Quality of Service) The set of network characteristics (such as bitrate, latency and reliability) applied to a data flow.
R
RAN (Radio Access Network) The part of the mobile network that connects devices to the core over the radio interface.
ROUTE (Real-time Object delivery over Unidirectional Transport) A protocol for delivering media objects and files over one-way transport, used in broadcast and multicast delivery.
RTC (Real-Time Communication) Low-latency, interactive media communication such as live conversational audio and video.
RTCP (RTP Control Protocol) A companion protocol to RTP that carries feedback on a media session's quality (packet loss, jitter, round-trip time) and control information such as participant identification.
S
SA1 / SA2 / SA4 3GPP working groups: SA1 handles service requirements, SA2 handles system architecture, and SA4 handles media codecs, formats and delivery.
SCEF (Service Capability Exposure Function) The EPC-era function that securely exposes network capabilities to external applications; the predecessor to the 5G Core's NEF.
SCP (Service Communication Proxy) A 5G Core function that provides indirect communication between network functions, handling message routing, discovery and load balancing on their behalf.
SCTP (Stream Control Transmission Protocol) A message-oriented transport protocol providing reliable, ordered or partially-ordered delivery; used to carry WebRTC data channels, typically over DTLS.
SMF (Session Management Function) A 5G Core function that manages PDU sessions (establishing, modifying and releasing them), allocates UE IP addresses, and selects and controls the UPF for a session.
STUN (Session Traversal Utilities for NAT) A protocol that lets a device discover its public IP address and port and the type of NAT it is behind, used to gather candidate addresses for ICE.
T
TMGI (Temporary Mobile Group Identity) An identifier used to address a particular multicast or broadcast service so devices know what to receive.
TSC (Time-Sensitive Communication) Communication with strict timing and reliability guarantees, used for applications that need deterministic delivery.
TURN (Traversal Using Relays around NAT) An extension to STUN that relays media or data through a server when a direct peer-to-peer path cannot be established.
U
UE (User Equipment) The end-user device (for example a phone, tablet or module) that connects to the mobile network.
UPF (User Plane Function) A 5G Core function that handles user-plane traffic: packet routing and forwarding, QoS enforcement, and interconnection to external data networks.
V
V3C (Visual Volumetric Video-based Coding) An MPEG family of coding tools for compressing volumetric (3D) visual content.
V-PCC (Video-based Point Cloud Compression) A method within V3C that compresses point-cloud data by mapping it onto video and coding it with video codecs.
W
WebRTC (Web Real-Time Communication) An IETF/W3C protocol stack for interactive, low-latency peer-to-peer media and data: RTP with RTCP feedback secured as DTLS-SRTP, ICE for connectivity, and data channels (SCTP over DTLS). Used by 3GPP's RTC work; see Standards: Real-Time Communications (RTC).
Numbers and reference points
5GMS (5G Media Streaming) The 5G system framework for delivering media streaming services, covering both downlink and uplink directions.
5GMSd (5G Media Streaming, downlink) The downlink part of 5G Media Streaming, delivering media from the network to devices.
5GMSu (5G Media Streaming, uplink) The uplink part of 5G Media Streaming, delivering media from devices to the network.
5GMS reference points
Reference points are the defined interfaces between 5G Media Streaming functions. The general points are M1 to M8; the d and u suffixes indicate the downlink and uplink variants.
M1 (M1d / M1u) Provisioning interface, used to configure media streaming sessions and resources.
M2 (M2d / M2u) Ingest interface between the content source and the media streaming functions.
M3 Internal interface between media streaming functions within the network.
M4 (M4d / M4u) Media delivery interface between the network media functions and the client.
M5 (M5d / M5u) Media session handling interface between the client and the network for session control.
M6 (M6d / M6u) Interface between the media client and the application on the device.
M7 (M7d / M7u) Interface between the media client and the media player or access functions on the device.
M8 (M8d / M8u) Application-level interface between the application on the device and the application provider.