EPS Bearer Context Synchronization in 5G Interworking
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Solution Overview
Problem
The interworking between fifth generation (5G) and evolved packet system (EPS) networks faces limitations in geographical coverage and mobility, leading to unsynchronized EPS bearer context status between user equipment (UE) and the network during inter-system changes from S1 mode to N1 mode, which affects seamless session continuity and QoS parameter management.
Innovation Solution
A method is introduced where the UE locally deactivates EPS bearer contexts in S1 mode without notifying the network, and upon inter-system change to N1 mode, includes EPS bearer context status information in registration requests to synchronize the status with the network, supporting interworking with 5GS by associating EPS bearer contexts with 5G QoS parameters and transferring them during handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the UE locally deactivates EPS bearer context without notifying the network in S1 mode, then the device complexity and signaling overhead are reduced, but the EPS bearer context status becomes unsynchronized between UE and network
Solution Approach 1:
The UE performs local deactivation of EPS bearer context in advance during S1 mode operation without immediate network notification. This preliminary action reduces signaling overhead while maintaining the ability to restore synchronization through periodic updates or event-triggered notifications when the UE transitions to N1 mode or when specific conditions are met.
2Reliability
If the UE maintains synchronized EPS bearer context status with the network during inter-system change, then the reliability of session continuity is improved, but the signaling overhead and network complexity increase
Solution Approach 1:
The patent introduces an intermediary mechanism where the UE maintains local EPS bearer context state information and periodically synchronizes with the network or triggers synchronization upon mode transitions. This intermediary approach ensures session continuity reliability while reducing continuous signaling overhead by using event-triggered or periodic updates rather than real-time synchronization.
3Adaptability or versatility
If the UE supports interworking with 5GS for deactivated EPS bearer context, then the adaptability of the system is improved, but the difficulty of detecting and measuring the bearer context status increases
Solution Approach 1:
The patent extends the bearer context management to a new dimension by supporting interworking between EPS and 5GS systems. The UE maintains EPS bearer context information in a deactivated state and can restore or transfer these contexts when transitioning to N1 mode for 5GS interworking. This dimensional extension allows the system to handle multi-RAT scenarios while managing complexity through structured context restoration procedures.
Data Source
AI summary
A method for synchronizing evolved packet system (EPS) bearer context status between a user equipment (UE) and a network can include locally deactivating an EPS bearer context of a packet data network (PDN) connection at the UE while the UE operates in S1 mode without notifying the network serving the UE, wherein interworking to a fifth generation system (5GS) is supported for the deactivated EPS bearer context, and upon inter-system change from S1 mode to N1 mode, including an EPS bearer context status information element (IE) in a registration request message indicating which EPS bearer contexts are active in the UE before the inter-system change.