RRC State Reporting for 5G Handover Without X2 Interface
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Solution Overview
Problem
In 5G wireless communication systems, managing the UE context when a user equipment (UE) moves from one base station to another is challenging, particularly when there is no direct X2 interface between the base stations, which complicates the delivery of UE context from the existing anchor eNB to a new anchor eNB.
Innovation Solution
A method where a base station reports the RRC state of a UE to a mobility management entity (MME) via the S1 or NG1 control plane interface, including UE context information, to ensure seamless transition and efficient management of UE context across base stations, even in the absence of an X2 interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UE context is managed through direct X2 interface between base stations, then handover efficiency is improved, but device complexity and network infrastructure requirements increase
Solution Approach 1:
The MME serves as an intermediary entity that receives RRC state information from the base station and manages UE context delivery to target base stations. This mediator approach allows UE context management without requiring direct X2 interfaces between all base station pairs, reducing network infrastructure complexity while maintaining handover efficiency.
Solution Approach 2:
The patent extracts the UE context management function from the base station-to-base station direct interface (X2) and relocates it to the core network (MME). By taking out the context management responsibility from the access network and placing it in the core network, the system reduces the complexity of inter-base station interfaces while preserving handover capabilities.
2Loss of information
If RRC state information is reported to MME for all state transitions, then network control and visibility are improved, but signaling overhead and network traffic increase
Solution Approach 1:
The patent implements partial reporting by sending RRC state information to the MME selectively based on specific transition events (particularly CONNECTED to IDLE and CONNECTED to INACTIVE transitions). This partial action approach provides the MME with sufficient visibility to manage UE context appropriately without generating excessive signaling overhead for every possible state change.
Solution Approach 2:
The system changes the reporting parameter from continuous or frequent reporting to event-triggered reporting based on specific RRC state transitions. This parameter change in the reporting mechanism reduces the quantity of signaling messages while maintaining adequate network visibility of RRC state changes that require MME awareness.
Data Source
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AI summary
Proposed are a method for reporting an RRC state of a terminal by a base station in a wireless communication system and an apparatus for supporting the same. A method for reporting an RRC state according to an embodiment of the present invention may comprise a step of reporting an RRC state of a terminal to a mobility management (MM).