Multiple options for realistic emulation of the N1 interface, including network slicing, to validate 5G Mobility Management

The N1 interface is an essential component for mobility management in 5G networks. It’s a transparent interface that transfers UE information regarding connection, mobility and sessions to the Access and Mobility Management Function (AMF) – similar to the NAS in 4G, which conveys information from the UE to the core network.

Mobility management is one of the core functions of any GSM, UMTS or 5G network, as it enables tracking of end user devices (i.e., subscribers), and the registration, management and authorisation of connections and sessions, and the services UEs are subscribed to. Of course, this all occurs as subscribers move between base stations – the essence of mobility.

N1 interface is essential for Mobility Management

In LTE networks the Mobility Management Entity (MME) controlled mobility management, but in the 5G era this cumbersome component has been separated into the Access and Mobility Management Function (AMF), the Session Management Function (SMF) and the Unified Data Management (UDM), providing significantly greater flexibility and scalability, as well as scope for multi-vendor solutions.

The AMF is part of the 3GPP 5G Architecture and is an essential component of the 5G network. Its primary tasks include:

• Registration Management – allows a User Equipment (UE) to register and de-register with the 5G network to access services.
• Connection Management – responsible for control plane signalling between the UE and AMF across the N1 interface.
• Reachability Management – ensures that a UE is always reachable.
• Mobility Management – is used to maintain knowledge of a UE's location within the network.
• Other functions relating to security and access management and authorisation.

Essentially, the AMF coordinates network handovers between base stations, and allows users to connect to the 5G network and access the services they are subscribed to as they move around. As such, it helps manage the high number of devices (including IoT) connected to the 5G network. It does this via the N1 interface.

It means that any 5G test solution must provide support for N1 in order to generate and validate and test realistic user traffic. Because the AMF coordinates network handovers between base stations, testing requires interaction with the AMF via the N1 interface to realistically emulate subscriber mobility.

Emblasoft supports comprehensive emulation of N1 interface

5G Mobility Management (5GMM) is involved mainly in the NAS (Non-Access Stratum) registration process and is mostly associated with the N1/N2 interface. The major functionality of 5GMM includes: Registration, De-registration, Call inactivity procedure, Connected mode procedure, and Connection management procedure.

5GMM enables identification of UEs, security and serves as a message transport for other communications between 5GC and the UE. 5GMM related procedures are divided into three categories depending on the purpose of the procedure and how they are initiated:

• Common procedures – which can always be initiated when the UE is in CM-CONNECTED state.
• Specific procedures – where only one UE-initiated specific procedure can be running for each of the Access types.
• Connection management procedures – which are used to establish secure signalling between the UE and the network.

Emblasoft’s comprehensive testing solution enables the testing of multiple 5GMM Common Procedures over the N1 interface, including:

• 5G AKA-based primary authentication and key agreement
• Registration
• Deregistration
• Security mode control
• Service request
• Identification
• NAS transport
• And much more – such as network, UE and 5GSM procedures. Get in touch to learn more!

It also enables testing of Primary Authentication and Key Agreement Procedure, Security Mode Control Procedure, Identification Procedure, and NAS Transport Procedure(s).

In addition, for 5GMM Specific Procedures, it offers: Registration Procedure and De-Registration Procedure testing capabilities.

Emblasoft also supports Network-Requested 5GSM Procedures Testing and UE-Requested 5GSM Procedures, and 5GS MM Messages, such as Authentication.

Response/Result/Failure/Reject, and so on – with the same options for Registration, De-Registration and UL and DL NAS Transport.

Our testing solution also supports multiple configurable settings for N1 interface testing, from basic (such as Mobile country and network codes) right through to more advanced settings, such as network slicing test capabilities.

N1 Simulation settings include multiple options for Registration, De-Registration, NAS_Release, PDU_Session, PDU_Session_Release, DATA and PING.

Importantly, the Emblasoft solution can provide a large set of statistics for N1 testing. For each type there are three measurement points:

• How many messages are initiated, “Initiating message”
• How many messages have a successful outcome, “Successful outcome”
• How many messages that have an unsuccessful outcome, “Unsuccessful outcome”

Our solution records different kinds of NGAP statistics, 5G NAS statistics, as well as numerous 5G Simulation statistics, providing a comprehensive breakdown of a huge number of variables and combinations of test use cases.

Test N1 interface traffic with network slicing

Emblasoft enables you to validate and test the N1 interface under lab conditions in test networks, as well as in live networks, ensuring that it can perform under different loads, with different traffic scenarios and for a realistically diverse mix of subscribers – and for different slices in parallel, or dynamically, as new slices are instantiated.

Importantly, the Emblasoft solution supports node-specific testing for different nodes in isolation – such as the AMF, SMF and others – AUSF, PCF, UDM, and so on. This allows operators to test the network before and during deployment, and vendors to validate functionality for their commercial offers.

Again, our solution also enables the validation of end-to-end performance and characteristics of different network slices, with emulation of the N1 interface.

To find out more, get in touch to arrange a demonstration.