School of Specs The 5G system architectureIn depth

Cheat sheet

The 5G system architecture

A guided read of 3GPP TS 23.501, in depth

Depth
In depth
Chapters
27
Reading
370 min
Questions
160
Document
TS 23.501 v20.2.0

Back to the course

The shape of it

1 Getting your bearings

  1. 1 Who writes this document, and why
  2. 2 How to read a 3GPP specification

2 The system in one piece

  1. 3 The shape of the 5G core
  2. 4 What each network function does
  3. 5 Services instead of interfaces
  4. 6 How one function finds another
  5. 7 Every name the system uses
  6. 8 What actually travels on the wire

3 What the system does

  1. 9 Registration, reachability and paging
  2. 10 Radio, Wi-Fi, cable — every way in
  3. 11 Using two accesses at once
  4. 12 The connection to a data network
  5. 13 Where the packets actually go
  6. 14 What the network promises
  7. 15 Rules, and paying for them
  8. 16 Who you are and who may listen
  9. 17 One network, many networks
  10. 18 Being served by somebody else's network

4 Reaching further

  1. 19 Living next to 4G
  2. 20 Computing close by, and opening the door
  3. 21 Emergency calls, messages, voice and location
  4. 22 Clocks, TSN and deterministic delivery

5 Special worlds

  1. 23 Very fast, very reliable, very picky
  2. 24 Networks that are not for everybody
  3. 25 Small devices, small messages
  4. 26 Relays, satellites, femtos and shared networks
  5. 27 Overload, energy, deployment and the rest

Keep these in your head

One from each chapter that has one. The course carries 32 in all — the rest are in the chapters.

  • 1.1 Who writes this document, and why

    A specification is not documentation of a product. It is a contract written before the products exist, so that products built separately still fit.

  • 2.1 How to read a 3GPP specification

    The scope clause is a boundary, not a summary. When this document stops answering, that is not a gap — it is another document's job, and the reference list tells you which one.

  • 3.1 The shape of the 5G core

    Everything else in this chapter follows from one decision: the core is a set of software functions that call each other, not a set of boxes joined by cables.

  • 4.1 What each network function does

    A network function is a named list of jobs, not a box. Five clauses in 6.2 — the AMF, the SMF, the UPF, the NWDAF and the SCP — say "some or all of the functionalities may be supported in a single instance", so one running process may be a whole function, a slice of one, or several.

  • 5.2 Services instead of interfaces

    Three levels, and people mix them up constantly: the network function, the service it offers, and the operation you actually call. Only the operation is a request.

  • 6.2 How one function finds another

    The NRF narrows the field; the requester makes the choice. Discovery answers "who could", selection answers "who now".

  • 7.1 Every name the system uses

    Every identifier in this chapter answers exactly one of three questions: who is the subscriber, what is the hardware, or which node and connection is this. Mix them up and nothing in the specification makes sense.

  • 8.2 What actually travels on the wire

    N2 is a relay as much as an interface. Some of what crosses it is for the AMF, and some is sealed traffic between the access node and the SMF that the AMF only forwards.

  • 9.1 Registration, reachability and paging

    A registration lasts days. A connection lasts seconds. The specification tracks them with two independent state machines because they change on entirely different timescales.

  • 10.1 Radio, Wi-Fi, cable — every way in

    The core never decides anything about the air. It stores things it cannot read, sends hints the radio network is free to ignore, and asks to be told when something it does care about changes.

  • 11.8 Using two accesses at once

    One session, two tunnels, two sets of rules. ATSSS rules tell the device what to do with uplink packets; N4 rules tell the UPF what to do with downlink ones. The steering mode is the shape of the split, the steering functionality is the machinery, and the PMF measurements are what either end uses to decide.

  • 12.2 The connection to a data network

    If you want a different data network, a different packet type or a different continuity promise, you do not modify the session. You build a second one.

  • 13.1 Where the packets actually go

    A UPF is not a gateway with a configuration file. It is a match-and-act engine that the SMF loads with rules, per session, over N4 (the link the SMF uses to program the UPF), while the session runs.

  • 14.2 What the network promises

    Everything else in clause §5.7 is about one question: how is a QoS Flow described, who is told, and who enforces it.

  • 15.1 Rules, and paying for them

    The test is simple. If a decision could reasonably come out differently for two subscribers on the same equipment in the same second, it is policy — not configuration.

  • 16.1 Who you are and who may listen

    Clause 5.10 answers "which box holds what, and who decides". Every "how does the maths work" question is answered in TS 33.501 [29], and looking for it here is a waste of an afternoon.

  • 17.1 One network, many networks

    A slice is not a physical thing a device connects to. It is a name the network agrees to serve a device on, and everything in §5.15 is about agreeing, checking and withdrawing that name.

  • 18.1 Being served by somebody else's network

    Roaming adds exactly one function, the border proxy. Everything else is the existing architecture cut in two along an operator boundary, with each function landing on one side or the other and a guarded gate at the cut.

  • 19.5 Living next to 4G

    N26 does not make the two systems equal. It makes the handover possible; what survives it is still decided session by session, by policy and by what the target can do.

  • 20.1 Computing close by, and opening the door

    Edge computing in 23.501 is not a new box. It is a set of existing mechanisms — user plane selection, traffic steering, session continuity, exposure — pointed at one goal: a nearby exit from the mobile network.

  • 21.11 Emergency calls, messages, voice and location

    Clause §4.4 and clause §5.16 rarely define a service. They define the exception a service needs: an indication in registration accept, a reserved ARP, a suspended restriction, a reference point. Read them as a list of exceptions and they stop looking like a grab bag.

  • 22.1 Clocks, TSN and deterministic delivery

    Every mechanism here serves one idea: the network is told the schedule in advance, so it can meet it, instead of reacting to traffic after it arrives.

  • 23.2.3 Very fast, very reliable, very picky

    The three levels differ in where the copy is made: end to end above the network (two sessions), inside the network (two tunnels), or below it (two transport paths). The higher the copy is made, the bigger the failure it survives, and the more of the work falls outside 3GPP.

  • 24.1 Networks that are not for everybody

    The two shapes differ in one thing: who owns the core. A stand-alone network has its own AMF (the function that keeps track of where a device is and whether it is reachable), its own subscriber database and its own name on the air. An integrated one is a slice and a data network name inside somebody else's network, and the device still needs that operator's subscription.

  • 25.1 Small devices, small messages

    Clause §5.31 does not add a network. It removes work: the user plane, the wake-ups, the QoS machinery, and the freedom to transmit whenever you like.

  • 26.2 Relays, satellites, femtos and shared networks

    5G MOCN shares the radio and nothing else. The new things are a list of operator identifiers on the air, and a prioritised copy of that list inside the AMF.

  • 27.3 Overload, energy, deployment and the rest

    Overload control has two layers that are easy to confuse. OVERLOAD START is sent to the radio network and stops connections being made at all. A back-off timer is sent to a phone and stops it asking again for a while.

Easy to get wrong

One from each chapter that has one. The course carries 75 in all.

  • 1.4 Who writes this document, and why

    The number is not a version and the series is not a priority. TS 23.502 is not a newer TS 23.501; it is the other half of the same job. Reading one without the other leaves you with an architecture and no procedures.

  • 2.2 How to read a 3GPP specification

    The bracket number belongs to this document alone. [3] means TS 23.502 here and something else entirely in TS 23.503. Never carry a bracket number across a document boundary, and never quote one at somebody without the TS number beside it.

  • 3.2 The shape of the 5G core

    An NF is not one machine. When the document says "the AMF" it means the role, and a real network may be running twenty AMF instances behind it. That is why the document has to say where an instance's state is kept §4.2.5 — any other instance may have to pick the work up.

  • 4.2 What each network function does

    The list of functions is not a deployment plan and not a list of servers. It also is not complete on its own: the CHF is named in §4.2.2 and never described in 6.2; the BSF is not even named there, yet both are used throughout the document.

  • 5.3 Services instead of interfaces

    A service name is not an address and not a protocol. Nsmf_PDUSession tells you nothing about where to send a packet — the endpoint address comes from discovery §6.3.1, and what actually travels on the wire is What actually travels on the wire.

  • 6.3 How one function finds another

    A group ID (UDM Group ID, PCF Group ID, AUSF Group ID) is not an address and not a set of machines. It is a bucket of subscribers. If the NRF has no local mapping from an identity to a group, it can ask the UDR for it, using a service built for exactly that lookup §6.3.1.

  • 7.3 Every name the system uses

    A GPSI is not "the public version of the SUPI". The specification states there is no implied 1-to-1 relationship between the two §5.9.8. One subscription may be reachable under several outside names, and code that assumes a lookup returns exactly one answer is wrong.

  • 8.3 What actually travels on the wire

    N1 is not a wire and has no stack of its own. It is a signalling connection between the device and the AMF, and whatever carries it belongs to the access network. On 3GPP radio the layers below NAS are specified in TS 38.300 and TS 36.300; on non-3GPP access they are the ones in §8.2.4 §8.2.2.2.

  • 9.2 Registration, reachability and paging

    "Registered" and "connected" are not two degrees of the same thing. A phone doing nothing all night is RM-REGISTERED and CM-IDLE the whole time: the network holds its context and may page it, but there is no access-network signalling connection, no N2 connection and no N3 user-plane connection anywhere §5.3.3.2.2.

  • 10.3 Radio, Wi-Fi, cable — every way in

    RRC_INACTIVE is not idle as far as the core is concerned. The device is CM-CONNECTED, the N2 connection exists, and the AMF has handed paging responsibility to the radio network. Reading "inactive" as "the core will page it" gets the whole paging chain wrong.

  • 11.2 Using two accesses at once

    This is not "two sessions with something clever on top". It is one session, one PDU Session ID, one IP address towards the data network, one QoS model, one anchor.

    Two sessions would give the application two addresses and no way to move a live flow between them. Here the two tunnels are two paths to the same place, and the choice between them is made per stream of packets, not per connection.

  • 12.1 The connection to a data network

    A PDU session is not a tunnel and not a radio bearer. Those are what carries it, and they come and go: the user plane of a session can be switched off entirely while the session lives on in the core §5.6.8. It is also not necessarily an IP connection — two of the five types carry no IP at all.

  • 13.5 Where the packets actually go

    "ARP" means two different things in this chapter. A few paragraphs back it was the address resolution protocol; here it is the Allocation and Retention Priority, and the two have nothing in common.

    Not required is not the same as never sent: this ARP decides which flows are admitted and which are pre-empted, and its value is not required to reach the UPF §5.8.2.7.

    What the UPF is given instead is a transport level marking value, which the SMF works out from the 5QI (the number that picks a row in an agreed table of delay, priority and loss), the Priority Level where that is signalled on its own, and optionally the ARP priority level.

    The SMF also hands the UPF the Session-AMBR, and for every GBR flow — a flow with a bit rate the network promises — the GFBR (the rate that is promised) and the MFBR (the most that flow may ever send) §5.8.2.7.

  • 14.4 What the network promises

    A 5QI is not an amount of bandwidth and not a channel. It is a scalar that refers to a set of characteristics agreed in advance — resource type, priority, delay budget, error rate, averaging window, burst volume. A standardised 5QI is sent as a bare number and nothing else, because both ends already have the table §5.7.2.1.

  • 15.5 Rules, and paying for them

    URSP is not enforcement and not a firewall. It is advice the phone applies to its own outgoing traffic. Enforcement happens in the UPF and the radio network, from PCC rules the phone never sees. A phone with no matching rule falls back on its local configuration §5.8.2.2.1.

  • 16.3 Who you are and who may listen

    "Authenticated" is not a permanent property of a device but a context with a scope. Two accesses mean two NAS contexts.

    Emergency service is the case where there may be none at all: where local regulation allows it, the network serves a device in limited service state regardless of whether it can be authenticated §5.16.4.1.

  • 17.2 One network, many networks

    A standardised SST value is not a promise of any particular speed or delay. Nothing in the table binds a number. It exists so two operators can recognise each other's slice kinds when a device roams — no network is required to support all of them, and the same service can be carried on a different SST.

  • 18.3 Being served by somebody else's network

    "Roaming" does not mean "your traffic is dragged back to your home country". That is home routing, and it is one of two options. Under local break-out the data path never leaves the visited network — only the signalling that proves who you are does.

  • 19.2 Living next to 4G

    These combined functions are optional, and not every device is put behind one. The network picks them from the device's mobility-management capability and its subscription. A device that will never cross can be served by a plain P-GW, or by a plain SMF and UPF §4.3.1.

  • 20.2.1 Computing close by, and opening the door

    "Edge" does not mean a second, special session. The most common arrangement is one ordinary PDU session that has grown a second anchor. The device keeps one address and one session; only the path inside the core changed.

  • 21.3 Emergency calls, messages, voice and location

    A text to an emergency centre is a normal short message, not a prioritised one. The AMF may hand the phone the local emergency numbers and their service types during registration so it can address one, and the document says plainly that this is handled without priority treatment §5.16.2.2.

  • 22.3 Clocks, TSN and deterministic delivery

    The TSCTSF does not carry time. It configures the parts that do — the PTP instances inside DS-TT and NW-TT — and it asks the PCF (the function that turns operator policy into the rules a session is run by) for a QoS Flow good enough to carry the PTP messages themselves §5.27.1.8. Its own traffic is signalling, not clock.

  • 23.3 Very fast, very reliable, very picky

    Duplication does not halve the measurements. When redundant transmission is on for the two N3 tunnels, both paths are monitored and the UPF reports their delays to the SMF independently §5.33.3.2.

  • 24.2 Networks that are not for everybody

    A PLMN ID inside an SNPN identity does not make the SNPN reachable by public subscriptions, and does not create roaming. An operator may use its own PLMN ID for an SNPN, but registration in the public network and movement between the two are still not supported with an SNPN subscription §5.30.2.1.

  • 25.3 Small devices, small messages

    There is no quality of service here. The QoS model of What the network promises does not apply to a session using this optimisation, because no user-plane resources exist to apply it to §5.31.4.1. Anything you meant to promise per flow, you cannot.

  • 26.2.1 Relays, satellites, femtos and shared networks

    Indirect sharing is not roaming with extra steps. In roaming the device's core is reached directly; here a third network sits in the path and terminates the control signalling, which is why the serving PLMN ID has two different meanings depending on who is talking to whom.

  • 27.4 Overload, energy, deployment and the rest

    A session management back-off timer does not stop your data. It stops the phone asking the core for session changes. Packets keep flowing on sessions that already exist, and the phone may still run a service request to bring the user plane back up for a congested DNN or slice §5.19.7.3.

The document's own words

One quotation per chapter that carries one, of 47.

  • 1.5 Who writes this document, and why

    The present document defines the Stage 2 system architecture for the 5G System. The 5G System provides data connectivity and services.

  • 2.2 How to read a 3GPP specification

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

  • 3.3 The shape of the 5G core

    Network functions within the 5GC Control Plane shall only use service-based interfaces for their interactions.

  • 4.3.1 What each network function does

    NOTE 1: Regardless of the number of Network functions, there is only one NAS interface instance per access network between the UE and the CN, terminated at one of the Network functions that implements at least NAS security and Mobility Management.

  • 5.1 Services instead of interfaces

    A reference point can be replaced by one or more service-based interfaces which provide equivalent functionality.

  • 6.5 How one function finds another

    Binding can be used to indicate suitable target NF producer instance(s) for NF service instance selection, reselection and routing of subsequent requests associated with a specific NF producer resource (context) and NF service.

  • 7.3 Every name the system uses

    A globally unique 5G Subscription Permanent Identifier (SUPI) shall be allocated to each subscriber in the 5G System and provisioned in the UDM/UDR. The SUPI is used only inside 3GPP system and its privacy is specified in TS 33.501 [29].

  • 8.2 What actually travels on the wire

    NGAP may support information that the AMF is just responsible to relay between the 5G-AN and the SMF. … NOTE 2: The N2 SM information is exchanged between the SMF and the 5G-AN transparently to the AMF.

  • 9.3 Registration, reachability and paging

    The UE context in AMF holds no valid location or routing information for the UE so the UE is not reachable by the AMF. However, some parts of UE context may still be stored in the UE and the AMF e.g. to avoid running an authentication procedure during every Registration procedure.

  • 10.2 Radio, Wi-Fi, cable — every way in

    However, the AMF does not know for how long the UE remains not reachable, thus the AMF shall not immediately de-register the UE. Instead, after the expiry of the Mobile Reachable timer, the AMF should clear the PPF and shall start an Implicit De-registration timer, with a relatively large value.

  • 11.1 Using two accesses at once

    The ATSSS feature enables a multi-access PDU Connectivity Service, which can exchange PDUs between the UE and a data network by simultaneously using one 3GPP access network and one non-3GPP access network and two independent N3/N9 tunnels between the PSA and RAN/AN.

  • 12.9 The connection to a data network

    When SMF adds a PDU Session Anchor (such as defined in clause 5.6.4) to a PDU Session Secondary authentication/authorization is not carried out, but SMF policies may require SMF to notify the DN when a new prefix or address has been added to or removed from a PDU Session or N6 traffic routing information has been changed for a PDU Session.

  • 13.5 Where the packets actually go

    ARP is used for admission control (i.e. retention and pre-emption of the new QoS Flow). The value of ARP is not required to be provided to the UPF.

  • 14.2 What the network promises

    The QoS Flow is the finest granularity of QoS differentiation in the PDU Session. … User Plane traffic with the same QFI within a PDU Session receives the same traffic forwarding treatment (e.g. scheduling, admission threshold).

  • 15.1 Rules, and paying for them

    The policy and charging control framework for the 5G System is defined in TS 23.503 [45].

  • 16.1 Who you are and who may listen

    Detailed security related network functions for 5G are described in TS 33.501 [29].

  • 17.9 One network, many networks

    The S-NSSAIs which map to S-NSSAIs of the HPLMN subject to an ongoing Network Slice-Specific Authentication and Authorization shall be included in the Pending NSSAI and removed from Allowed NSSAI.

  • 18.3 Being served by somebody else's network

    NOTE 1: The use of an UPF in the VPLMN e.g. enables VPLMN charging, VPLMN LI and minimizes the impact on the HPLMN of the UE mobility within the VPLMN (e.g. for scenarios where SSC mode 1 applies).

  • 19.5 Living next to 4G

    The support for N26 interface between AMF in 5GC and MME in EPC is required to enable seamless session continuity (e.g. for voice services) for inter-system change.

  • 20.3.2 Computing close by, and opening the door

    The AF specific UE Identifier shall not correspond to a MSISDN; it is represented as a GPSI in the form of an External Identifier. When used as an AF specific UE identifier, the External Identifier provided by the 5GCN shall be different for different AF.

  • 21.6 Emergency calls, messages, voice and location

    Based on local regulation, the network supporting Emergency Services for UEs in limited service state provides Emergency Services to these UE, regardless whether the UE can be authenticated, has roaming or Mobility Restrictions or a valid subscription.

  • 22.4 Clocks, TSN and deterministic delivery

    The Burst Arrival Time and Periodicity component of the TSCAI that the SMF sends to the 5G-AN are specified with respect to the 5G clock.

  • 23.2.1 Very fast, very reliable, very picky

    It is out of scope of 3GPP how to make use of the duplicate paths for redundant traffic delivery end-to-end.

  • 24.9 Networks that are not for everybody

    A PDU Session provides access to one and only one 5G VN group. The PDU Sessions accessing to a certain 5G VN group should all anchor at the same network, i.e. the common home network of 5G VN group members.

  • 25.3 Small devices, small messages

    The Control Plane CIoT 5GS Optimisation is used to exchange user data between the UE and the SMF as payload of a NAS message in both uplink and downlink directions, avoiding the establishment of a user plane connection for the PDU Session.

  • 26.3 Relays, satellites, femtos and shared networks

    … IAB uses the CU/DU architecture defined in TS 38.401 [42] and the IAB operation via F1 (between IAB-donor and IAB-node) is invisible to the 5GC; IAB performs relaying at layer-2 and therefore does not require a local UPF; …

  • 27.1 Overload, energy, deployment and the rest

    A 5GC NF is considered to be in overload when it is operating over its nominal capacity resulting in diminished performance (including impacts to handling of incoming and outgoing traffic).

The words

146 the course explains, out of 221 the document defines — all of them.

(R)AN
(Radio) Access Network
5G DDNMF
5G Direct Discovery Name Management Function
5G LAN
5G Local Area Network
5G VN
5G Virtual Network
5G-AN
5G Access Network
5G-EIR
5G-Equipment Identity Register
5G-GUTI
5G Globally Unique Temporary Identifier
5G-RG
5G Residential Gateway
5G-S-TMSI
5G S-Temporary Mobile Subscription Identifier
5GC
5G Core Network
5GS
5G System
5QI
5G QoS Identifier
ADRF
Analytics Data Repository Function
AF
Application Function
AMF
Access and Mobility Management Function
ATSSS
Access Traffic Steering, Switching, Splitting
ATSSS-LL
ATSSS Low-Layer
AUSF
Authentication Server Function
AnLF
Analytics Logical Function
BSF
Binding Support Function
CAG
Closed Access Group
CAPIF
Common API Framework for 3GPP northbound APIs
CHF
Charging Function
CN PDB
Core Network Packet Delay Budget
CP
Control Plane
DCCF
Data Collection Coordination Function
DCS
Default Credentials Server
DN
Data Network
DNAI
DN Access Identifier
DNN
Data Network Name
DRX
Discontinuous Reception
DS-TT
Device-side TSN translator
DetNet
Deterministic Networking
EBI
EPS Bearer Identity
EIF
Energy Information Function
FAR
Forwarding Action Rule
FN-RG
Fixed Network RG
FQDN
Fully Qualified Domain Name
GBRSS
Guaranteed Bit Rate Streaming Service
GEO
Geostationary Orbit
GFBR
Guaranteed Flow Bit Rate
GIN
Group ID for Network Selection
GMLC
Gateway Mobile Location Centre
GPSI
Generic Public Subscription Identifier
GUAMI
Globally Unique AMF Identifier
HMTC
High-Performance Machine-Type Communications
HR
Home Routed (roaming)
I-SMF
Intermediate SMF
IAB
Integrated access and backhaul
IPUPS
Inter PLMN UP Security
L4S
Low Latency, Low Loss and Scalable Throughput
LADN
Local Area Data Network
LBO
Local Break Out (roaming)
LEO
Low Earth Orbit
LMF
Location Management Function
MB-SMF
Multicast/Broadcast Session Management Function
MB-UPF
Multicast/Broadcast User Plane Function
MBSF
Multicast/Broadcast Service Function
MBSR
Mobile Base Station Relay
MBSTF
Multicast/Broadcast Service Transport Function
MCX
Mission Critical Service
MEO
Medium Earth Orbit
MFAF
Messaging Framework Adaptor Function
MFBR
Maximum Flow Bit Rate
MICO
Mobile Initiated Connection Only
MPQUIC
Multi-Path QUIC
MPS
Multimedia Priority Service
MPTCP
Multi-Path TCP Protocol
MWAB
Mobile gNB with wireless access backhauling
N3IWF
Non-3GPP InterWorking Function
N3QAI
Non-3GPP QoS Assistance Information
N5CW
Non-5G-Capable over WLAN
NAI
Network Access Identifier
NAT
Network Address Translation
NEF
Network Exposure Function
NF
Network Function
NGAP
Next Generation Application Protocol
NID
Network identifier
NPN
Non-Public Network
NR
New Radio
NRF
Network Repository Function
NSACF
Network Slice Admission Control Function
NSI ID
Network Slice Instance Identifier
NSSAA
Network Slice-Specific Authentication and Authorization
NSSAAF
Network Slice-specific and SNPN Authentication and Authorization Function
NSSAI
Network Slice Selection Assistance Information
NSSF
Network Slice Selection Function
NSSRG
Network Slice Simultaneous Registration Group
NSWOF
Non-Seamless WLAN offload Function
NW-TT
Network-side TSN translator
NWDAF
Network Data Analytics Function
ON-SNPN
Onboarding Standalone Non-Public Network
PCF
Policy Control Function
PDR
Packet Detection Rule
PDU
Protocol Data Unit
PEGC
PIN Element with Gateway Capability
PEI
Permanent Equipment Identifier
PEMC
PIN Element with Management Capability
PIN
Personal IoT Network
PINE
PIN Element
PNI-NPN
Public Network Integrated Non-Public Network
PPF
Paging Proceed Flag
PPI
Paging Policy Indicator
PSA
PDU Session Anchor
PSDB
PDU Set Delay Budget
PSER
PDU Set Error Rate
PSIHI
PDU Set Integrated Handling Information
PTP
Precision Time Protocol
PVS
Provisioning Server
QFI
QoS Flow Identifier
RACS
Radio Capabilities Signalling optimisation
RIM
Remote Interference Management
RQA
Reflective QoS Attribute
RSN
Redundancy Sequence Number
S-NSSAI
Single Network Slice Selection Assistance Information
SCP
Service Communication Proxy
SD
Slice Differentiator
SEAF
Security Anchor Functionality
SEPP
Security Edge Protection Proxy
SMF
Session Management Function
SMSF
Short Message Service Function
SNPN
Stand-alone Non-Public Network
SO-SNPN
Subscription Owner Standalone Non-Public Network
SSC
Session and Service Continuity
SST
Slice/Service Type
SUCI
Subscription Concealed Identifier
SUPI
Subscription Permanent Identifier
TAI
Tracking Area Identity
TNGF
Trusted Non-3GPP Gateway Function
TSC
Time Sensitive Communication
TSCAI
Traffic Assistance Information
TSCTSF
Time Sensitive Communication and Time Synchronization Function
TSN
Time Sensitive Networking
TWIF
Trusted WLAN Interworking Function
UAS NF
Uncrewed Aerial System Network Function
UCMF
UE radio Capability Management Function
UDM
Unified Data Management
UDR
Unified Data Repository
UDSF
Unstructured Data Storage Function
UL
Uplink
UPF
User Plane Function
URLLC
Ultra Reliable Low Latency Communication
URSP
UE Route Selection Policy
VLAN
Virtual Local Area Network
W-AGF
Wireline Access Gateway Function
ePDG
evolved Packet Data Gateway

Where to look it up

The 167 clauses of TS 23.501 this course is built from.

§Foreword§1§2§3§3.1§3.2§4.1§4.2.1§4.2.2§4.2.3§4.2.4§4.2.5§4.2.5a§4.2.6§4.2.7§4.2.8§4.2.9§4.2.10§4.2.11§4.2.12§4.2.13§4.2.14§4.2.15§4.2.16§4.2.17§4.2.18§4.2.19§4.3§4.3.2§4.4§5.2§5.2.2§5.2.4§5.2.7§5.3§5.3.4.1§5.3.4.1.1§5.4§5.4.4.1a§5.5§5.6§5.6.3§5.7§5.7.1.11§5.7.7§5.8§5.8.2.14§5.9§5.9.10§5.10§5.11§5.12§5.13§5.14§5.15§5.15.2.1§5.15.2.2§5.15.3§5.15.6§5.15.9§5.15.11.3§5.16§5.16.4.1§5.17§5.18§5.19§5.20§5.20a§5.20b§5.20c§5.20d§5.21§5.22§5.23§5.24§5.25§5.26§5.27§5.28§5.28a§5.29§5.30§5.30.2.3§5.31§5.32§5.33§5.34§5.34.3§5.35§5.35A§5.36§5.37§5.38§5.39§5.40§5.41§5.42§5.43§5.44§5.45§5.46§5.47§5.48§5.49§5.50§5.51§5.52§5.53§5.54§6.1§6.2§6.2.2§6.2.3§6.2.7§6.2.17§6.2.21§6.3§6.3.1§6.3.2§6.3.4§6.3.7.1§6.3.11§7.1.1§7.1.2§7.1.3§7.1.4§7.1.5§7.2.1§7.2.2§7.2.3§7.2.4§7.2.5§7.2.6§7.2.7§7.2.29§7.2.30§7.3§8§Annex A§Annex B§Annex C§Annex D§E.1§Annex F§G.1§G.2.1§G.2.2§G.3§G.4§Annex H§Annex I§Annex J§Annex K§Annex L§Annex M§Annex N§Annex O§Annex P§Annex Q§Annex R§Annex S§Annex T§Annex U§U.1§Annex V§Annex W§Annex X

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