Interworking Functions for 4G-to-5G PDU Session Continuity
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Solution Overview
Problem
The existing 4G network upgrade to 5G network architecture requires costly and time-consuming adaptations, disrupting legacy 4G services and hindering the introduction of new services like network slicing.
Innovation Solution
Implementing interworking functions (IWFs) that facilitate protocol conversion and communication between 4G and 5G network components, allowing legacy MMEs to establish PDU sessions in 5G Core networks, enabling efficient integration of 5G capabilities without significant upgrades to existing 4G infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If legacy 4G network components are upgraded to 5G architecture, then 5G capabilities and new services like network slicing are enabled, but the upgrade process is costly and time-consuming, disrupting legacy 4G services
Solution Approach 1:
An interworking function (IWF) is introduced as an intermediary component that enables communication and protocol conversion between legacy 4G network components (MME, SGW, PGW) and new 5G core network functions (AMF, SMF, UPF). This mediator allows the network to support both 4G and 5G protocols simultaneously, enabling 5G capabilities without forcing a complete architecture replacement, thereby reducing upgrade complexity and cost while maintaining legacy service compatibility
2Adaptability or versatility
If complete architecture replacement from 4G to 5G is implemented, then new services are introduced, but legacy 4G services are disrupted
Solution Approach 1:
The network architecture is segmented into distinct 4G and 5G domains that operate independently but are connected through interworking functions. Legacy 4G services continue to operate through traditional MME/SGW/PGW components while new 5G services are introduced through separate AMF/SMF/UPF functions. This segmentation allows both legacy and new services to coexist without mutual disruption, maintaining reliability of existing services while enabling service evolution
3Adaptability or versatility
If significant upgrades to existing 4G infrastructure are performed, then 5G features are enabled, but costs and time requirements increase
Solution Approach 1:
Interworking functions are deployed in advance within the existing 4G infrastructure to prepare the network for 5G integration. These IWF components are pre-configured with both 4G and 5G protocol stacks, allowing the network to rapidly activate 5G features when needed without requiring extensive last-minute modifications. This preliminary preparation significantly reduces deployment time and costs by avoiding disruptive architecture changes
Data Source
AI summary
In one aspect, a control plane Interworking Function (IWF-C) is used to establish a Packet Data Unit (PDU) session in a data communications network. A create session request is received, for example from a Mobile Management Entity (MME). A create session management context request is generated by the IWF-C and transmitted to a Session Management Function (SMF). A create session management context request response is received from the SMF. A create session request response is generated by the IWF-C and sent, for example to the MME. In other aspects, control plane policy interworking and user plane interworking is provided between components of 4G and 5G networks.