LTE to 5G Handover Bearer Context Correlation
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Solution Overview
Problem
The challenge in wireless communication systems is to ensure seamless service continuity during handovers between evolved packet systems (EPS) and 5G systems, particularly in intersystem mobility scenarios.
Innovation Solution
A communication device and method that enable handover from a long-term evolution (LTE) network to a new radio (NR) network by keeping the EPS bearer ID and PDU Session ID when switching between networks, allowing for the application of configurations received from the original network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the UE locally deletes EPS bearers that cannot correlate with the HO command during handover from LTE to 5G, then the handover process can be completed, but service continuity and data communication may be interrupted due to loss of bearer context information
Solution Approach 1:
The UE performs preliminary correlation between EPS bearers and QoS flows before deleting any bearer contexts. By proactively matching bearers with corresponding QoS flows using the provided mapping information, the UE ensures that only bearers with valid correspondences are deleted, preventing unnecessary service interruptions while still completing the handover process efficiently
Solution Approach 2:
The UE uses feedback from the HO command containing QoS flow ID and Session ID information to make informed decisions about bearer deletion. This feedback mechanism allows the UE to verify bearer-QoS flow correspondences before deletion, ensuring that service continuity is maintained for all bearers that have valid mappings while still enabling cleanups of orphaned bearers
2Reliability
If the UE maintains all EPS bearer contexts during handover from LTE to 5G, then service continuity is preserved, but device complexity and memory usage increase due to retaining unnecessary bearer information
Solution Approach 1:
The UE extracts and utilizes the QoS flow ID and Session ID mapping information from the HO command to identify which EPS bearers have valid correspondences in the 5G network. By separating bearers with valid mappings from those without, the UE can selectively delete only the unnecessary bearer contexts, reducing device complexity while maintaining service continuity for active bearers
Solution Approach 2:
The UE discards (deletes) EPS bearer contexts that cannot be correlated with any QoS flow in the 5G network, as these bearers are no longer needed. This selective discarding reduces the burden on device memory and complexity management, while the UE recovers (maintains) bearers that have valid correspondences, ensuring service continuity is preserved
3Device complexity
If mapping information between EPS bearers and QoS flows is not provided during handover, then the handover command can be simplified, but the UE cannot properly correlate bearers with flows leading to potential service interruption
Solution Approach 1:
The network performs preliminary preparation by including QoS flow ID and Session ID mapping information in the HO command before the handover executes. This preliminary provision of mapping information enables the UE to perform accurate bearer-QoS flow correlation without adding complexity to the handover execution phase, preventing information loss while maintaining command efficiency
Solution Approach 2:
The QoS flow ID and Session ID information act as an intermediary that bridges the EPS bearer context in the LTE network and the corresponding QoS flows in the 5G network. This intermediary mapping information is embedded in the HO command, allowing the UE to correlate bearers with flows without direct exposure to complex network internal structures, thus preserving information while maintaining command simplicity
Data Source
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AI summary
A communication device configured for handover from a long-term evolution (LTE) network to a new radio (NR) network comprises at least one storage device and at least one processing circuit, coupled to the at least one storage device, wherein the at least one storage device stores, and the at least one processing circuit is configured to execute, instructions of transmitting a first protocol data unit (PDU) Session identity (ID) to the LTE network; receiving a first EPS bearer ID identifying a first EPS bearer, from the LTE network, wherein the first EPS bearer ID is associated with the first PDU Session ID; configuring a first data radio bearer, DRB, associated to the first EPS bearer ID, with the LTE network; communicating data via the first DRB with the LTE network; receiving a first handover command from the LTE network, wherein the first handover command indicates the communication device to hand over to the NR network; keeping the first EPS bearer ID and the first PDU Session ID, when the first handover command comprises a first DRB configuration associated to the first PDU Session ID; and releasing the first EPS bearer ID, when the first handover command does not comprise the first DRB configuration.