The 5G Core is designed to connect everything — smartphones, IoT devices, enterprise systems, and beyond. But not all of these connections come through traditional 3GPP-defined radio access like 5G NR. Wi-Fi, fixed broadband, and other non-3GPP access technologies are also essential parts of today’s connectivity.
This is where the Non-3GPP InterWorking Function (N3IWF) comes in. Acting as the secure gateway between non-3GPP networks and the 5G Core, N3IWF enables seamless access and mobility, allowing users and enterprises to enjoy a unified 5G experience across heterogeneous networks.
The Core Responsibilities of N3IWF
N3IWF does not generate radio access itself. Instead, it ensures that devices connected through Wi-Fi or fixed broadband can access the 5G Core with the same security, policy, and mobility management as native 5G radio connections.
1. Secure Authentication and Tunneling
N3IWF establishes secure IPsec tunnels between user devices and the 5G Core. This guarantees data confidentiality and integrity when users connect via Wi-Fi or other non-3GPP access networks.
2. Integration with 5G Core Functions
N3IWF interacts with AMF and UPF to provide seamless mobility management and session continuity. It ensures that users switching between 5G radio and Wi-Fi remain connected without interruptions.
3. Policy and QoS Enforcement
By working with PCF and SMF, N3IWF enforces operator policies and Quality of Service (QoS) rules for non-3GPP connections. This means that critical applications, such as video calls or enterprise VPNs, still receive the required performance.
Inside the N3IWF Workflow
When a device connects to a Wi-Fi hotspot or fixed broadband, it first establishes an IPsec tunnel with the N3IWF. The N3IWF authenticates the device, coordinates with the AMF for mobility management, and sets up data forwarding through the UPF.
As the user moves, N3IWF ensures that sessions remain continuous — whether the connection is over cellular or Wi-Fi. Applications and services remain uninterrupted, delivering a truly seamless experience.
Why N3IWF Matters in 5G
In real-world networks, users constantly move between cellular coverage and Wi-Fi hotspots. Without N3IWF, these transitions would cause service breaks, inconsistent security, or degraded performance.
N3IWF provides a unified framework that makes non-3GPP access a integral part in 5G networks, ensuring secure, seamless, and reliable connectivity across all access types.
N3IWF in Real-World Applications
Enterprise Campuses: Employees roam between indoor Wi-Fi and outdoor 5G without losing connectivity.
Public Hotspots: Wi-Fi access integrates with the 5G Core, providing secure authentication and QoS.
Remote Work and VPNs: N3IWF enables secure connections to enterprise networks over broadband.
IoT Deployments: Devices using non-cellular access, such as industrial Wi-Fi, can still connect to the 5G Core.
N3IWF: The Seamless Access Enabler
N3IWF is not about providing radio coverage — it is about unifying access. It ensures that Wi-Fi, fixed broadband, and other non-3GPP technologies integrate smoothly with the 5G Core, offering users and enterprises a consistent and secure experience.
As 5G continues to expand toward 6G, N3IWF will remain a key enabler of heterogeneous connectivity, powering smart campuses, digital enterprises, and always-on mobility.
