5G • RAN
Event B2
Measurement Event B2
Inter-RAT event triggered when serving 5G cell drops below Th1 and inter-RAT neighbor (LTE) exceeds Th2.
Technical Explanation
Event B2 triggers inter-RAT handover to 4G LTE when 5G coverage expires. The 5G PCell must be worse than threshold Th1 and the target LTE neighbor must be better than threshold Th2. Upon receipt, the gNodeB commands handover to E-UTRA, preventing dropped connections at 5G coverage boundaries.
Key Functions
- Primary trigger for inter-RAT handover from 5G to 4G LTE
- Requires 5G cell to degrade below Th1 while LTE cell exceeds Th2
- Guarantees continuous connectivity when moving outside 5G coverage footprint
Specifications
3GPP TS 38.331
Interfaces
Uu
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