WiFi acces to EPC architecture and associated VoWiFi/WiFi Calling service

Course outline : The objective of this course is to present the interworking between WLAN (non-3GPP access) and the Evolved Packet Core (ePC). One of the applications foreseen is to offload data traffic from 4G to Wi-Fi. This scenario is called Trusted WiFi or Carrier WiFi. Offload enables to transfer part of the mobile data traffic from mobile users to a fixed broadband network via WiFi cells connected to ePC. This solution enables strong mobile network authentication when accessing the ePC via WiFi, as well as data session mobility between WiFi and LTE and vice versa. Furthermore, the user may access to all his mobile data services. With Carrier WiFi, the user may activate all his APNs (e.g., Internet , MMS, IMS, etc.) as is he were with mobile radio. Another important scenario is considered called non-Trusted WiFi where the user makes use of ePC only for his IMS related APNs for a service called VoWiFi or WiFi Calling. The client uses WiFi to directly access to his Internet services without going through ePC and WiFi calling via ePC to access to his telephony services including, voice, videotelephony, and SMS. The user is connected to ePC via WiFi for WiFi calling and accesses to the IMS architecture. Furthermore handover between VoLTE and VoWiFi is ensured to provide voice call continuity. WiFi calling enables the user access to his telephony services via WiFi when the mobile radio coverage is absent or does not offer a high signal strength.
In this seminar, we discuss IP connectivity using non-3GPP access (i.e., WLAN to the ePC). We examine architectures for Trusted & Non-Trusted WLAN access, mobility management, session management, QoS management, and underlying charging issues. The VoWiFi/WiFi Calling service is described in terms of IMS registration, IMS session control and its differences with VoLTE as well as all the associated handover procedures between VoLTE and VoWiFi and between VoWiFi .

1. Introduction
1.1. Why WLAN Interworking (I-WLAN) ?
1.2. 3GPP path for Evolution of I-WLAN
1.3. Offload Scenarios
1.3.1. ANDSF Function (Access Network Discovery and Selection Function) for the discovery of offload methods to apply to IP flows
1.3.2. MAPCON Method : Multiple Access PDN Connectivity
1.3.3. IFOM Method : IP Flow Mobility
1.3.4. NSWO Method : Non-seamless WLAN offload)
1.3.5. WiFi Calling scenario
1.3.6. Carrier WiFi scenario
1.4. Mobility Management, Session Management and Security Handling in EPS with non 3GPP access as WLAN/WiFi
1.5. Non-Trusted WLAN access scenario
1.6. Trusted WLAN access scenario

2. WLAN Access to ePC
2.1. Access Network Selection
2.2. IP Address Allocation and Mobility handling
2.3. Charging and QoS handling
2.4. Non-Trusted WLAN Access:
2.4.1. Architecture and Interfaces
2.4.2. ePDG (SWm, S2b)
2.4.3. PDN GW (S2b, S2c, S6b)
2.4.4. AAA Server (SWm, SWx, S6b, SWa, SWd)
2.4.5. Roaming scenario and related architecture
2.5. Trusted WLAN Access:
2.5.1. Architecture and Interfaces
2.5.2. TWAN (STa and S2a)
2.5.3. PDN GW (S2a, S2c, S6b)
2.5.4. 3GPP AAA Server (STa, SWx, S6b, SWd)
2.5.5. Roaming scenario and related architecture

3. Authentication, Authorization and Security
3.1. Security in WLAN vs 3GPP Networks
3.2. HSS vs 3GPP AAA-Server (SWx)
3.3. Identities used for security, NAI, USIM info, etc
3.4. 3GPP EAP-AKA
3.5. IKEv2
3.6. Authentication And Authorization procedures

4. SWx interface between 3GPP AAA Server and HSS
4.1. Authentication Procedure
4.1.1. Multimedia-Authentication-Request/Answer (MAR/MAA)
4.2. Location Update Procedure
4.2.1. Server-Assignment-Request/Answer (SAR/SAA)
4.2.2. Registration-Termination-Request/Answer (RTR/RTA)
4.3. Data subscription handling Procedure
4.3.1. Push-Profile-Request/Answer (PPR/PPA)
4.4. Fault management Procedure
4.4.1. Use of PPR/PPA et SAR/SAA

5. SWm interface between ePDG and 3GPP AAA Server
5.1. Authentication/Authorization Procedure
5.1.1. Diameter EAP Request.Answer (DER/DEA)
5.1.2. Authenicate Authorize Request/Answer (AAR/AAA)
5.1.3. Re-Authorize Request/Answer (RAR/RAA)
5.2. Session Termination Procedure
5.2.1. Session Termination Request/Answer (STR/STA)
5.2.2. Abort Session Request/Answer (ASR/ASA)

6. STa interface between non-3GPP access network NAS and 3GPP AAA server
6.1. Authentication/Authorization Procedure
6.1.1. Diameter EAP Request.Answer (DER/DEA)
6.1.2. Authenicate Authorize Request/Answer (AAR/AAA)
6.1.3. Re-Authorize Request/Answer (RAR/RAA)
6.2. Session Termination Procedure
6.2.1. Session Termination Request/Answer (STR/STA)
6.2.2. Abort Session Request/Answer (ASR/ASA)

7. S6b interface between PDN GW and 3GPP AAA server
7.1. Authentication/Authorization Procedure
7.1.1. Diameter EAP Request.Answer (DER/DEA)
7.1.2. Authenicate Authorize Request/Answer (AAR/AAA)
7.1.3. Re-Authorize Request/Answer (RAR/RAA)
7.2. Session Termination Procedure
7.2.1. Session Termination Request/Answer (STR/STA)
7.2.2. Abort Session Request/Answer (ASR/ASA)

8. S2a and S2b
8.1. GTP variant
8.1.1. GTPv2-C for the control plane
8.1.2. GTPv1-U for the user plane
8.2. PMIP/GRE variant
8.3. Differences between the two variants and the impacts on the architecture of non 3GPP access to ePC

9. VoWiFi/WiFi Calling
9.1. WiFi Calling Architecture : GSMA IR 51
9.2. Similarities and differences between VoLTE and WiFi Calling
9.3. WiFi Calling registration and differences with VoLTE
9.4. WiFi Calling session establishment and differences with VoLTE
9.5. WiFi Calling service invocation
9.6. Policy control during WiFi Calling session establishment/modification/release and differences with VoLTE
9.7. WiFi Calling roaming and differences with VoLTE
9.8. WiFi Calling emergency session and UE location
9.9. VoLTE session mobility between VoLTE and VoWiFi and vice versa