A presentation/video looking at how true fixed-mobile convergence will be achieved in 5G. The main motivation for this tutorial is the fact that 5G is designed to enable access-neutral service availability. What this means is that 5G services in future will be available seamlessly not just over 5G NR but also over Wi-Fi and Wireless access networks. The tutorial discusses: • Untrusted non-3GPP access networks; • Trusted non-3GPP access networks (TNAN); • Wireline access networks; • Non-5G-Capable over WLAN (N5CW); • Access Traffic Steering, Switching and Splitting (ATSSS) All our #3G4G5G slides and videos are available at: Videos: https://www.youtube.com/3G4G5G Slides: https://www.slideshare.net/3G4GLtd 5G Page: https://www.3g4g.co.uk/5G/ Free Training Videos: https://www.3g4g.co.uk/Training/

1. True Fixed-Mobile
Convergence (FMC) with 5G
@3g4gUK

2. Background Material
©3G4G

3. Support of non-3GPP access
©3G4G
• 3GPP TS 23.501:4.2.8 - Support of non-3GPP
access
• The 5G Core Network supports connectivity of
UEs via non-3GPP access networks, e.g. WLAN
access networks
• The following types of non-3GPP access networks
are defined:
1. Untrusted non-3GPP access networks;
2. Trusted non-3GPP access networks (TNAN);
3. Wireline access networks.

4. Control plane
function group
5GS Service Based Architecture (SBA)
©3G4G
Data Network
(DN)gNodeB
(NG-RAN)
5G UE
User plane
function
UPF
AMF SMF
NSSF NEF NRF AUSFFE PCFFEUDM AF
UDR
FE
UDC
N1
N2
N3 N6
N4
Nnssf Nnef Nnrf Nudm Nausf Npcf Naf
AF Application Function
AMF Access and Mobility management Function
AUSF Authentication Server Function
DN Data Network
FE Front End
N3IWF Non-3GPP InterWorking Function
NEF Network Exposure Function
NRF NF Repository Function
NSSF Network Slice Selection Function
PCF Policy Control Function
(R)AN (Radio) Access Network
SEPP Security Edge Protection Proxy
SMF Session Management Function
UDM Unified Data Management
UDR Unified Data Repository
UDSF Unstructured Data Storage Function
UE User Equipment
UPF User Plane Function

5. Simplified 5GS SBA
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
N2
N3
N1(Air Interface)
HPLMN
HPLMN Home PLMN

6. Support of non-3GPP access
©3G4G
Non-3GPP
Access
Untrusted
Trusted
Wireline
5G Core
(5GC)
3GPP
Access
(NG-RAN)

7. Trusted and Untrusted Non-3GPP Access: General Concepts #1
©3G4G
• The 5G Core Network supports both untrusted non-3GPP access
networks and trusted non-3GPP access networks (TNANs).
• An untrusted non-3GPP access network shall be connected to the 5G
Core Network via a Non-3GPP InterWorking Function (N3IWF).
• A trusted non-3GPP access network shall be connected to the 5G Core
Network via a Trusted Non-3GPP Gateway Function (TNGF).
• Both the N3IWF and the TNGF interface with the 5G Core Network CP
and UP functions via the N2 and N3 interfaces, respectively.

8. Trusted and Untrusted Non-3GPP Access: General Concepts #2
©3G4G
• A non-3GPP access network may advertise the PLMNs for which it
supports trusted connectivity and the type of supported trusted
connectivity (e.g. "5G connectivity").
• Therefore, the UEs can discover the non-3GPP access networks that can
provide trusted connectivity to one or more PLMNs.
• The UE decides to use trusted or untrusted non-3GPP access for
connecting to a 5G PLMN by using procedures not defined by 3GPP.

9. Trusted and Untrusted Non-3GPP Access: General Concepts #3
©3G4G
• When the UE decides to use untrusted non-3GPP access to connect to
a 5G Core Network in a PLMN:
• the UE first selects and connects with a non-3GPP access network; and then
• the UE selects a PLMN and an N3IWF in this PLMN. The PLMN/N3IWF selection
and the non-3GPP access network selection are independent.
• When the UE decides to use trusted non-3GPP access to connect to a
5G Core Network in a PLMN:
• the UE first selects a PLMN; and then
• the UE selects a non-3GPP access network (a TNAN) that supports trusted
connectivity to the selected PLMN. In this case, the non-3GPP access network
selection is affected by the PLMN selection.

10. Untrusted Non-3GPP Access Architecture
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
N3IWF
Untrusted
Non-3GPP
Access
N2
N2
N3
N3
N1(Air Interface)
Y2
Y1
N1
NWu
HPLMN
Non-3GPP
Networks
Based on 3GPP TS 23.501 Figure 4.2.8.2.1-1: Non-roaming architecture for 5G Core Network with untrusted non-3GPP
access

11. 5GS SBA with Untrusted Non-3GPP Access
©3G4G
Data
Network
(DN)gNodeB
(NG-RAN)
5G UE
User
plane
function
UPF
AMF SMF
NSSF NEF NRF AUSFFE PCFFEUDM AF
UDR
FE
UDC
N1
N2
N3 N6
N4
Nnssf Nnef Nnrf Nudm Nausf Npcf Naf
N3IWF
N2
N1
Y2
N3
Y1
NWu
Data
Network
(DN)
User plane
function
UPF
N6

12. Trusted Non-3GPP Access Network (TNAN)
Trusted Non-3GPP Access Architecture
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
Trusted
Non-3GPP
Access
Point
(TNAP)
N2
N3
N1
(Air Interface)
HPLMN
Based on 3GPP TS 23.501 Figure 4.2.8.2.1-2: Non-roaming architecture for 5G Core Network with trusted non-3GPP
access
Trusted
Non-3GPP
Gateway
Function
(TNGF)
N3
N2
Tn
Yt
N1
NWt
Ta

13. 5GS SBA with Trusted Non-3GPP Access
©3G4G
Data
Network
(DN)gNodeB
(NG-RAN)
5G UE
User
plane
function
UPF
AMF SMF
NSSF NEF NRF AUSFFE PCFFEUDM AF
UDR
FE
UDC
N1
N2
N3 N6
N4
Nnssf Nnef Nnrf Nudm Nausf Npcf Naf
TNAN
N2
N1
Y2
N3
Yt
NWt
Data
Network
(DN)
User plane
function
UPF
N6

14. Introducing the Wireline Access Terminology #1
©3G4G
• RG: The Residential Gateway (RG) is a device providing, for example
voice, data, broadcast video, video on demand, to other devices in
customer premises.
• 5G-RG: A 5G-RG is a RG capable of connecting to 5GC playing the role
of a UE with regard to the 5G core. It supports secure element and
exchanges N1 signalling with 5GC. The 5G-RG can be either a 5G-BRG
or 5G-CRG.
• 5G-BRG: The 5G-BRG is a 5G-RG defined in BBF.
• 5G-CRG: The 5G-CRG is a 5G-RG specified in DOCSIS MULPI.

15. Introducing the Wireline Access Terminology #2
©3G4G
• W-AGF: The Wireline Access Gateway Function (W-AGF) is a Network
function in W-5GAN that provides connectivity to the 5G Core to 5G-
RG and FN-RG.
• FN-RG: A Fixed Network Residential Gateway (FN-RG) is a RG that it
does not support N1 signalling and it is not 5GC capable.
• W-5GAN: The Wireline 5G Access Network (W-5GAN) is a wireline AN
that connects to a 5GC via N2 and N3 reference points. The W-5GAN
can be either a W-5GBAN or W-5GCAN.
• W-5GBAN: Wireline 5G BBF Access Network defined in BBF.
• W-5GCAN: Wireline 5G Cable Access Network defined in CableLabs.

16. W-5GAN
Wireline Non-3GPP Access Architecture with 5G-RG
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
N2
N3
N1
Based on 3GPP TS 23.501 Figure 4.2.8.4-1: Non- roaming architecture for 5G Core Network for 5G-RG with Wireline
5G Access network and NG RAN
W-AGF
N3
N2
N1
Y4
5G-RG

17. W-5GAN
Wireline Non-3GPP Access Architecture with FN-RG
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
N2
N3
Based on 3GPP TS 23.501 Figure 4.2.8.4-2: Non- roaming architecture for 5G Core Network for FN-RG with Wireline
5G Access network and NG RAN
W-AGF
N3
N2
N1
Y5
FN-RG

18. 5GS SBA with Wireline Access
©3G4G
Data
Network
(DN)gNodeB
(NG-RAN)
User
plane
function
UPF
AMF SMF
NSSF NEF NRF AUSFFE PCFFEUDM AF
UDR
FE
UDC
N1
N2
N3 N6
N4
Nnssf Nnef Nnrf Nudm Nausf Npcf Naf
W-5GAN
N2
N1
N3
Y4
Data
Network
(DN)
User plane
function
UPF
N6
5G-RGFN-RG
Y5
N1

19. N5CW: Non-5G-Capable over WLAN #1
©3G4G
• The devices that do not support 5GC NAS signalling over WLAN access
are referred to as "Non-5G-Capable over WLAN" UEs, or N5CW UEs for
short.
• A N5CW UE is not capable to operate as a 5G UE that supports 5GC
NAS signalling over a WLAN access network, however, it may be
capable to operate as a 5G UE over NG-RAN.
• Release-16 specifies 5GC architectural enhancements that enable
N5CW UEs to access 5GC via trusted WLAN access networks.

20. N5CW: Non-5G-Capable over WLAN #2
©3G4G
• Not all trusted WLAN access networks support 5GC access from N5CW
UEs.
• To support 5GC access from N5CW UEs, a trusted WLAN access
network must support a TWIF function.
• When a N5CW UE performs an EAP-based access authentication
procedure to connect to a trusted WLAN access network, the N5CW UE
may simultaneously be registered to a 5GC of a PLMN. The 5GC
registration is performed by the TWIF function in the trusted WLAN
access network, on behalf of the N5CW UE.

21. Trusted WLAN Access Network
5GC access from N5CW UEs Architecture
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
N2
N3
Based on 3GPP TS 23.501 Figure 4.2.8.5.2-1: Non-roaming and LBO Roaming Architecture for supporting 5GC access
from N5CW UEs
Trusted
WLAN
Interworking
Function
(TWIF)
N3
N2
N1
YtN5CW
UE
Trusted
WLAN
Access
Point
(TWAP)
Yw

22. ATSSS: Access Traffic Steering, Switching and Splitting
©3G4G
• New Access Traffic Steering, Switching and Splitting (ATSSS)
functionality has been designed in Release 16, which allows traffic
steering across multiple accesses at a finer granularities than a PDU
session.
• The ATSSS feature is an optional feature in Release 16 both on the UE
and the 5GC network
• ATSSS introduces the notion of Multi Access PDU session, a PDU
session for which the data traffic can be served over one or more
concurrent accesses (3GPP access, trusted non-3GPP access and
untrusted non-3GPP access).

23. Non-3GPP
Access
Architecture Reference Model for ATSSS Support
©3G4G
AMF SMF
UPF DN
N11
N4
N6
3GPP
Access
N2
N3
N1
Based on 3GPP TS 4.2.10-1: Non-roaming and Roaming with Local Breakout architecture for ATSSS support
N3
N2
N1
PCF
N7
UE
MPTCP
functionality
ATSSS-LL
functionality
MPTCP
Proxy
functionality
PMF

24. References
©3G4G
• 3GPP TS 23.501 v16.1.0: System Architecture for the 5G System; Stage
2 – Section 4.2 contains details regarding this topic
• WBA and NGMN Alliance: RAN Convergence Paper, August 2019
• Broadband Forum – MR-427: 5G Fixed-Mobile Convergence, July 2018
• Wireless Broadband Alliance (WBA) Whitepaper – WBA 5G Workgroup:
Unlicensed Integration with 5G Networks, October 2018
• Metaswitch – The 5G Access Gateway Function (AGF): An Evolutionary
Tale, June 2019

25. Thank You
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