Handover (A3 Event) Margin Calculator
Will the UE report a better neighbour, or is the margin too tight?
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Handover (A3 Event) Margin Calculator by TheCalcTools
How the Handover (A3 Event) Margin Calculator works
Enter the serving and neighbour RSRP and the A3 parameters.
The A3 entering condition is: Mn + Ocn − Hys > Ms + Ocs + Off.
The result shows the required neighbour advantage, the actual one and the margin.
The formula
Worked example
Using the default values shown in the calculator:
| Serving cell RSRP (dBm) | -98 dBm |
|---|---|
| Neighbour cell RSRP (dBm) | -93 dBm |
| A3 offset (dB) | 3 |
| Hysteresis (dB) | 1 |
| Cell individual offset, neighbour (dB) | 0 |
| Cell individual offset, serving (dB) | 0 |
| Time to trigger (ms) | 320 |
- Required advantage = 3 + 1 + 0 − 0 = 4.0 dB.
- Neighbour is 5.0 dB stronger, so the margin is 1.0 dB. Event: Met: after 320 ms the UE sends a measurement report.
Result:
| Neighbour must exceed serving by (dB) | 4.0 |
|---|---|
| Actual neighbour − serving (dB) | 5.0 |
| Margin (positive = event entered) | 1.0 |
| A3 entering condition | Met: after 320 ms the UE sends a measurement report |
Frequently asked questions
What happens when the offset is too small?
Ping-pong handovers: the UE hops back and forth between cells. Increase the offset, hysteresis or time-to-trigger.
What if it is too large?
Late handovers cause call drops or interruption because the UE stays on a weak serving cell too long.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.