I would like to understand about Reselection and Handover for two specific technologies

5G NR
1

Hello Experts,

I have trouble understanding Handover and Reselection (From NSA to LTE and vice-versa) when I analyse the logs. Can you please help me understand how it takes place and also how to verify in the logs.

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There’s no real “handover” between NSA and LTE — in EN-DC the UE is always anchored on LTE. “LTE → NSA” is just an SgNB Addition (NR leg added), “NSA → LTE” is an SgNB Release (NR leg removed). Your LTE connection never moves. And in idle mode NSA doesn’t exist at all — it’s plain LTE reselection; the 5G icon only means upperLayerIndication is set in SIB2.

In the logs:

  • Leg added: B1 measConfig → MeasurementReport (B1) → RRCConnectionReconfiguration with nr-SecondaryCellGroupConfig → RACH on NR.

  • Leg removed: NR A2 report + reconfiguration removing the SCG (graceful), or SCGFailureInformationNR (failure — read the cause inside it: t310-Expiry, randomAccessProblem, etc.).

Lots of SCGFailure instead of clean A2 releases = NR coverage/RACH problem, not mobility design.

Stuck on a specific capture? Send it with your chipset/tool type to fkamanzi@gmail.com and I’ll walk the flow with you.

1 Like
3

Hello,

The easiest way to differentiate them is by checking the UE state.

  • Cell Reselection happens in Idle mode and is UE-controlled. You’ll mainly see cell camping, SIB information, and reselection based on priorities/measurement criteria.

  • Handover happens in Connected mode and is network-controlled. In logs, look for Measurement Report → RRC Reconfiguration (HO Command) → Random Access → RRC Reconfiguration Complete.

For NSA ↔ LTE, you’ll often see NR SCG Addition/Release depending on NR coverage while LTE usually remains the anchor.

These two articles explain the concepts and the signaling flow quite well: