1. 3GPP status presentation

2. Background – Development of intentional dedication of resources for UE access.
GPRS or EPS
The 3GPP architecture for GPRS and EPS provided data services uniformly based on subscription characteristics – both best effort service and guaranteed bit rate service. In practice, the latter is very expensive so was used principally to deliver VoIP services.
In Release 10, the Low Access Priority Indicator was introduced to steer MTC devices to specific functional elements in the network, to prevent a mix of use between MTC and ‘normal-subscriber’ access, depending on the selection criteria (e.g. load) of the radio access node.
In Release 13 and 14, Dedicated Core Network functionality further elaborated selection of resources to support UEs by the core network, based on subscription classification and other criteria. UE
EPC UE
EPC UE
EPC / Decor

3. Context – 5G conceived of as support for specialized access to provide distinctive capabilities.
In order to support communication services of a particular connection type
Compose a collection of 5G network functions and specific RAT capabilities;
Control configuration to allow flexible and rapid assignment of resources;
Provide only support necessary for the use case, avoiding all other functionality;
Allow interfaces to the system so that 3rd parties can access information and control over slices to deliver services.
Provides independent usage of the network simultaneously for different service delivery.
It is foreseen that a virtualized core network will be essential to achieve efficiency in cost, maximum use of common resources, flexibility and speed of realizing new configurations.
See: NGMN 5G White Paper, Feb 2015.

4. 5G Timeline – Phase 1 is the current target.
2016
2017
2018
2019 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Rel-14 / 5G Study
Rel-16 / 5G Phase 2
Rel-15 / 5G Phase 1
P1 Studies
P1 Normative
Requirements
P2 Studies
P2 Normative
Architecture
Protocols

5. Architecture - EPS vs. 5G System (user plane view).
In the EPS, there is a common resource pool and a 1:1 relationship between the UE and the RAN-SGW.
In the 5G System, resources in the RAN and Core Network are separated and assigned without these constraints.
Slices

6. 5G Status – Core Network representations
Each Network Function (NF) is represented by the services it comprises from and their exposed interfaces.
Instead of defining a single and unique reference point between two different Core network entities, as before, each one of the services belonging to the NF may be exposed through a number of operations that can be consumed by other authorized NFs.
CORE CONTROL PLANE NETWORK FUNCTION
SERVICE 1
SERVICE 2
SERVICE n …

7. Requirements – Specified by 3GPP, guides the specification of architecture and protocol realization.
Description: Slicing allows the operator to provide customized networks. A network slice can provide the functionality of a complete network. This comprises both the Radio and Core Network functions.
Selected requirements: The 5G System allows the network operator to create / modify / delete a network slice, define and update its capabilities, configuration, scale resources assigned to it, differentiate policies and performance of different network slices.
Selected characteristics:
The 5G System allows services and UEs to be associated with network slices.
A UE accesses services using one or more network slices.
Traffic and services in one network slice have no impact on traffic and services in other network slices in the same network.
See TS , frozen June, 2017.
A new study item “Business Role Models for Network Slicing” (SP ) was agreed recently. This will conclude in September, 2018.
Proves that 3GPP considers more how to make use of slices.
Tacitly acknowledges that for slicing to directly result in revenues and value, more is needed than will currently go into the standard.

8. Architecture - A simplified view.
User plane entities
Per-slice functions
Session Management Function (SMF)
Manages session aspects, including paging, PDU session control, based on subscription & policy info.
User Plane Function
Data handling, forwarding, queuing, charging, policy enforcement, etc.
Control-plane entities
Per-UE functions
Network Slice Selection Function
Select network slice instances to serve a UE, support roaming, support mobility…
Policy Control Function
Supplies rules for QoS control and charging, to the SMF and the UE. The AMF chooses a PCF, provides it to SMF……… AND SMF may decide to use it (would mean an UE based PCF) or use another one (likely dedicated per slice)
Unified Data Management
Supports structured & unstructured data, centralizes state to ease virtualization, reduce context transfer.
Service-based interfaces to and between each of function in the CN.
See TS , TS , to freeze Dec 2017.

9. Slice Management and Orchestration – Study Conclusions.
Supports the Network Slice Instance (NSI) lifecycle and model - including components, resources used by the components, the Network Slice Template (NST), policies and configurations.
Requirements derived from TS , and and NGMN documents, determined by means of use cases and evaluation.
See TR , concluded Sep, Normative work to complete June, 2018.

10. Management and Orchestration, continued.
Conclusions and recommendatio ns concluded, normative work proceeds.
Further conclusions (i.e. how to support the functions shown to the right) have not been achieved.

11. Charging Aspects
Charging for the 5G system is currently under study. What follows are current assumptions and these could change.
It is assumed that existing Rf offline charging interfaces will be reused (Rf, Ga).
Charging of a UE served by one or more NSI.
The Charging Trigger Function (CTF) will be per slice.
For offline-charging: The Charging Data Function (CDF) that generates Charging Data Records (CDR) and the Charging Gateway Function (CGF) may be per-slice or not, depending on deployment.
For online-charging: the OCS will be per-PLMN, not per-slice, or optionally, a per-slice OCF through a CGF can communicate with a per-PLMN Account Balance Management Function (ABMF)
Credit management and reporting remain ‘for further study.’
See TR , to conclude Dec 2017.

12. Protocol Design
Service-Based Architecture (SBA) will be used for all control signalling within a network slice instance.
SBA for Rel-15 Conclusions
HTTP/2 is adopted as the application layer protocol for service based interfaces.
TCP is adopted as the transport layer. QUIC, binary encoding and other aspects are left ‘for further study’ in future releases.
JSON is adopted as the serialization protocol.
RESTful design whenever possible and custom methods otherwise.
2 HTTP client-server pairs to support notifications.
OpenAPI as Interface Definition Language (IDL)
Signaling and interfaces defined by the architecture are currently being studied.

13. 5G status – self discoverable network
3GPP Rel 15 has defined a new network entity that will serve as repository of (O&M related) information regarding accessibility and characteristics of deployed network functions and services
The information will be used for registration and discovery of NF services to interact with (e.g. of the required network functions for the selected Network Slice instance).
Management of 5G networks will develop the relation between the O&M system and the repository.

14. 5G status - analytics
5GC has specified a Network Exposure Function, which receives information from other networks functions and stores it. The stored information can be re-exposed and used for purposes such as analytics.
In addition, 5GC contains a network analytics logical function, operator managed, intended to provide slice specific data analytics for policy decisions not related to subscribers.

15. Aspects of NFV related to mobile networks
Only management aspects of NFV are addressed in 3GPP
Specifications for mobile networks that include virtualized network functions:
TS Management concept, architecture and requirements
TS /1/2/3 – Configuration Management
TS /6/7/8 – Fault Management
TS /1/2/3 – Performance Management
TS /6/7/8 – Life Cycle Management

16. Aspects of NFV related to mobile networks - continue
The mobile network management architecture mapping relationship between 3GPP and NFV-MANO architectural framework (TS )

17. Backup slides

18. NRF (NF repository function) per TS 23.501
Supports service discovery function. Receive NF Discovery Request from NF instance, and provides the information of the discovered NF instances (be discovered) to the NF instance.
Maintains the NF profile of available NF instances and their supported services.
NF profile of NF instance maintained in an NRF includes the following information:
NF instance ID
NF type
PLMN ID
Network Slice related Identifier(s) e.g. S-NSSAI, NSI ID
FQDN or IP address of NF
NF capacity information
NF Specific Service authorization information
Names of supported services
Endpoint information of instance(s) of each supported service
Other service parameter, e.g., DNN, notification endpoint for each type of notification that the NF service is interested in receiving.
It is expected service authorization information is usually provided by OA&M system, and it can also be included in the NF profile in case that e.g. an NF instance has an exceptional service authorization information.
In the context of Network Slicing, based on network implementation, multiple NRFs can be deployed at different levels:
PLMN level (the NRF is configured with information for the whole PLMN),
shared-slice level (the NRF is configured with information belonging to a set of Network Slices),
slice-specific level (the NRF is configured with information belonging to an S-NSSAI).

19. NWDAF (Network Data Analytics Function) per TS 23.501
Represents operator managed network analytics logical function.
Provides slice specific network data analytics to the PCF.
network data analytics (i.e., load level information) to PCF on a network slice level
is not required to be aware of the current subscribers using the slice.
notifies / publishes slice specific network status analytic information to the PCF(s) that are subscribed to it.
PCF(s) can collect directly slice specific network status analytic information from NWDAF. PCF uses that data in its policy decisions.

20. NEF (Network Exposure Function) per TS 23.501
Provides a means to securely expose the services and capabilities provided by 3GPP network functions for e.g 3rd party, internal exposure/re-exposure, Application Functions, Edge Computing.
Provides a means for the Application Functions to securely provide information to 3GPP network, e.g. Mobility Pattern, communication pattern.
In that case the NEF may authenticate, authorize and throttle the Application Functions.
Translates between information exchanged with the AF and information exchanged with the internal network function.
E.g. translates between an AF-Service-Identifier and internal 5G Core information such as S- NSSAI
Receives information from other network functions (based on exposed capabilities of other network functions).
May implement a Front End (NEF FE) to store the received information
The stored information can be accessed and "re-exposed" by the NEF to other network functions and Application Functions, and used for other purposes such as analytics.

21. Network slicing discussions status
TS System Architecture for the 5G System [under development]
TS NR; Overall description; Stage-2 [under development]
TS NG-RAN; Architecture description [under development]
A Network Slice is defined within a PLMN and shall include:
the Core Network CP and UP Network Functions and
in the serving PLMN, at least one of the following:
the NG Radio Access Network described in 3GPP TS
the N3IWF functions to the non-3GPP Access Network
A single UE can simultaneously be served by one or more Network Slice instances
A PDU session belongs to one and only one specific Network Slice instance per PLMN
The selection of the Network Slice instance(s) for a UE is triggered by the first contacted AMF in a registration procedure normally by interacting with the NSSF (Network Slice Selection Function)

22. Network slicing discussions status - continue
End to End services provided by NSI(s), per TS