Every expert has their own definition of Radio Link Failure(RLF), UE can detect RLF in certain conditions like
1.The measured RSRP is too low
2. It failed to decode PDCCH due to power signal quality (e.g, low RSRP, RSRQ)
3. It failed to decode PDSCH due to power signal quality (e.g, low RSRP, RSRQ).
Timers related to this are T310, N310, N311
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