5G Brings New Twists on Core Network Validation

2019-07-31 | 5 min read

Validating the core network in the 5G era is much different than in the past. Some of the most important changes are the adoption of a service-based architecture (SBA) and the control and user plane separation (CUPS) of the evolved packet core (EPC) nodes to increase deployment flexibility.

In addition, mobile network operators (MNOs) are no longer building the core network in incremental steps, with months between adding nodes and interfaces. Since the 3^rd Generation Partnership Project’s (3GPP) release 15 (rel-15) in December 2017, they must implement the entire core network at once.

Validating the 5G core (5GC) thus requires a holistic approach. By isolating nodes, engineers can test individual interfaces, nodes, or groups of nodes and entire functionalities across the 5GC in an end-to-end approach.

Simulating user equipment (UE) across multiple nodes is critical to validate functionalities and services. Key areas of focus include testing the user plane function (UPF), access and mobility management function (AMF), and service-based architecture (SBA) nodes in different node-level scenarios as well as for performance.

Testing UPF in Isolation

When testing the UPF with a node isolation approach, the nodes run on both the control and user planes. The test tool simulates the 5G base station (gNB), the session management function (SMF), and the data network. Assessing UPF performance in a variety of scenarios is critical. Engineers need to validate key performance indicators (KPIs) per node and for multiple ones. Quality of service (QoS) validation is particularly important for the UPF.

Figure 1 shows the UPF isolation use case.

Testing AMF in Isolation

For the AMF, the UEs send connection and session information over N1 and N2 interfaces. The AMF is responsible for handling connection and mobility management tasks. All messages related to session management are forwarded over the N11 reference interface through the SMF. When testing the AMF, the focus is on control plane functional and capacity testing. Testing the AMF in isolation requires testing coordination of the N1/N2 interfaces from the gNB and simulation of the SBA nodes. The AMF should be tested in different node-level scenarios and for performance.

Figure 2 shows the AMF isolation use case.

Testing SBA Nodes in Isolation

Similar to UPF and AMF testing, various node-level and performance test scenarios must be deployed for testing the SBA nodes. At the node level, it is important to test for registration to network repository function (NRF), node failover, and elastic scaling. From a performance perspective, it is important to validate the rate of various procedures for UE authentication and context management, as well as subscriber data management. SBA nodes have a dual role as producer and consumer. Validating both roles is essential for a holistic approach.

Figure 3 shows an isolation use case example for the SBA nodes.

Conclusion

MNOs need a new test approach to validate the 5GC network. SBA and CUPS translate into significant challenges for engineers. For more information on 5G core challenges and solutions, click here:

Two recent KEE webcasts also discuss this topic: