5G • RAN
Event A3
Measurement Event A3
Measurement event triggered when a neighbor cell becomes an offset better than the SpCell (serving cell).
Technical Explanation
Event A3 is the universal trigger for intra-frequency and inter-frequency handover: Mn + Ofn + Ocn - Hys > Mp + Ofp + Ocp + Off. When a neighboring cell outperforms the serving cell by an offset (e.g. 3 dB) for Time-to-Trigger (TTT), the UE sends a measurement report, prompting the gNodeB to issue a handover command.
Key Functions
- Primary trigger for intra-frequency and inter-frequency handovers
- Requires neighbor to exceed serving cell by offset Off for duration TTT
- Incorporates cell-specific offsets (Ocn) and hysteresis (Hys)
Specifications
3GPP TS 38.331
Interfaces
Uu
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