5G SA:
The 5G Standalone (SA) call flow involves several stages and messaging between various network elements. Here’s a basic overview of the call flow, along with examples of Information Elements (IEs) that can be checked in Qualcomm eXtensible Diagnostic Monitor (QXDM) and a flow chart
UE Registration and Attach
-
UE powers on and sends a Registration Request message to the 5G Core Network (5GC).
-
5GC authenticates and authorizes the UE and sends a Registration Accept message.
-
UE attaches to the 5G network and sends an Initial UE Message to the 5GC.
Example IEs in QXDM: Registration Request, Registration Accept, Initial UE Message, Authentication Request/Response, Authorization Request/Response.
Radio Resource Control (RRC) Connection Setup
-
5GC selects the appropriate 5G New Radio (NR) node and sends a RRC Connection
Request message. -
UE receives the RRC Connection Request and sends a RRC Connection Setup message
to the 5G-NR node. -
5G-NR node sends a RRC Connection Setup Complete message to the UE.
Example IEs in QXDM: RRC Connection Request, RRC Connection Setup, RRC Connection Setup Complete
Establishment of Data Radio Bearer (DRB)
- UE sends a Service Request message to the 5GC with the desired QoS parameters.
- 5GC selects the appropriate RAN node and sends a Session Management Request message.
- RAN node establishes the DRB with the UE.
- UE receives the Session Management Accept message.
Example IEs in QXDM: Service Request, Session Management Request, DRB Setup Request, Session Management Accept.
Data Transfer
- UE sends data packets to the RAN node over the established DRB.
- RAN node forwards the packets to the 5GC.
- 5GC routes the packets to the appropriate destination.
Example IEs in QXDM: Data Packets, QoS Parameters, User Plane Data.
Release of DRB and UE De-Registration
- UE sends a Session Release Request message to the 5GC.
- 5GC releases the DRB resources and sends a Session Release Response message.
- UE sends a Deregistration Request message to the 5GC.
- 5GC releases the UE’s resources and sends a Deregistration Accept message.
Example IEs in QXDM: Session Release Request, Session Release Response, Deregistration Request, Deregistration Accept.
Here’s an overview flow chart of the 5G SA call flow:
- UE → 5GC: Registration Request
- 5GC → UE: Registration Accept
- UE → 5GC: Initial UE Message
- 5GC → 5G-NR Network: RRC Connection Request
- 5G-NR Network → UE: RRC Connection Setup
- UE → 5G-NR Network: RRC Connection Setup Complete
- UE → 5G-NR Network: Service Request (QoS Parameters)
- 5G-NR Network → 5GC: Session Management Request
- 5GC → RAN: DRB Setup Request
- RAN → UE: Session Management Accept
- UE → 5G-NR Network: Session Management Accept
- UE → RAN: Data Packets
- RAN → 5GC: User Plane Data
- UE → 5GC: Session Release Request
- 5GC → UE: Session Release Response
- UE → 5GC: Deregistration Request
- 5GC → UE: Deregistration Accept
5G NSA:
The 5G Non-Standalone (NSA) call flow involves several stages and messaging between various network elements. Here’s a simplified overview of the call flow, along with examples of Information Elements (IEs) that can be checked in Qualcomm eXtensible Diagnostic Monitor (QXDM) and a flow chart:
LTE Attach and EPS Bearer Establishment
- UE attaches to the LTE network and establishes EPS bearers.
- LTE network assigns the LTE RAN node and the 5G Core Network (5GC) to the UE.
- 5GC selects the appropriate 5G-NR (New Radio) node and sends a RRC Connection Request message.
Example IEs in QXDM: LTE Attach Request, LTE Attach Accept, EPS Bearer Context Activation Request, RRC Connection Request.
5G-NR Cell Selection and Registration
- UE sends a RRC Connection Setup message to the 5G-NR node.
- 5G-NR node selects the appropriate 5GC and sends a Registration Request message.
- 5GC verifies the UE’s identity and allocates resources for the UE.
- UE receives the Registration Accept message.
Example IEs in QXDM: RRC Connection Setup, Registration Request, Registration Accept, 5G Network Identity.
Establishment of Data Radio Bearer (DRB)
- UE sends a Service Request message to the 5GC with the desired QoS parameters.
- 5GC selects the appropriate RAN node and sends a Session Management Request message.
- RAN node establishes the DRB with the UE.
- UE receives the Session Management Accept message.
Example IEs in QXDM: Service Request, Session Management Request, DRB Setup Request, Session Management Accept.
Data Transfer
- UE sends data packets to the RAN node over the established DRB.
- RAN node forwards the packets to the 5GC.
- 5GC routes the packets to the appropriate destination.
Example IEs in QXDM: Data Packets, QoS Parameters, User Plane Data.
Release of DRB and UE De-Registration
- UE sends a Session Release Request message to the 5GC.
- 5GC releases the DRB resources and sends a Session Release Response message.
- UE sends a Detach Request message to the LTE network.
- LTE network releases the EPS bearer resources and sends a Detach Accept message.
Example IEs in QXDM: Session Release Request, Session Release Response, Detach Request, Detach Accept.
Here’s a simplified flow chart of the 5G NSA call flow:
- UE → LTE Network: LTE Attach Request
- LTE Network → UE: LTE Attach Accept
- UE ↔ EPS Network: EPS Bearer Context Activation Request/Response
- EPS Network → UE: RRC Connection Request
- UE → 5G-NR Network: RRC Connection Setup
- 5G-NR Network → UE: Registration Request
- UE → 5G-NR Network: Registration Accept
- UE → 5G-NR Network: Service Request (QoS Parameters)
- 5G-NR Network → UE: Session Management Request
- UE → RAN: DRB Setup Request
- RAN → UE: Session Management Accept
- UE → 5G-NR Network: Session Management Accept
- UE → RAN: Data Packets
- RAN → 5G-NR Network: User Plane Data
- 5G-NR Network → UE: Session Release Response
- UE → LTE Network: Detach Request
- LTE Network → UE: Detach Accept
Credits: 