5G • RAN
Timer T311
RRC Connection Re-establishment Timer
Timer bounding cell selection following Radio Link Failure; if no suitable cell is found before expiry, UE enters IDLE.
Technical Explanation
Upon declaring RLF, the UE starts timer T311 (values 1000ms to 30000ms). The UE executes cell search to find a suitable cell. If a cell is found, the UE transmits an RRCReestablishmentRequest; if T311 expires before finding a cell, the UE tears down all contexts and drops to RRC_IDLE.
Key Functions
- Bounds the duration allowed for cell search after Radio Link Failure
- Prevents indefinite battery drain while out of cellular coverage
- Forces transition to RRC_IDLE if no suitable cell is found before expiry
Specifications
3GPP TS 38.331
Interfaces
Uu
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