5G NR RRC Timers
Comprehensive reference for LTE and 5G NR Radio Resource Control (RRC) timers
Technology & Filters
RRC Timer Reference Table
LTE SPECIFICATIONS| TIMER | CATEGORY | PURPOSE | TYPICAL (MS) | RANGE |
|---|---|---|---|---|
| T300 | Connection Establishment | RRC Connection Request timeout | 1000 | 100-2000 |
| T301 | Connection Re-establishment | RRC Connection Re-establishment Request timeout | 1000 | 100-2000 |
| T304 | Handover | Handover execution timer | 2000 | 50-10000 |
| T310 | Radio Link Failure | Radio Link Failure detection timer | 1000 | 0-6000 |
| T311 | Radio Link Failure | RRC Re-establishment opportunity timer | 3000 | 1000-30000 |
Protocol Counters & Constants
N-SERIES CONSTANTS| COUNTER | DESCRIPTION | TYPICAL | RANGE | RELATED TIMER |
|---|---|---|---|---|
| N300 | Maximum number of RRCConnectionRequest transmissions Standard protocol constant | 2 | 1-8 | T300 |
| N301 | Maximum number of RRCConnectionReestablishmentRequest transmissions Standard protocol constant | 2 | 1-8 | T301 |
| N310 | Number of consecutive out-of-sync indications from L1 to start T310 Lower values (1-2) = faster RLF detection, Higher values (10-20) = more tolerance to temporary issues | 1 | 1-20 | T310 |
| N311 | Number of consecutive in-sync indications from L1 to stop T310 Lower values (1-2) = faster recovery, Higher values = more stable recovery confirmation | 1 | 1-20 | T310 |
Technical Implementation
RRC timers operate at Layer 3 (Control Plane) of the radio interface. They are supervised by the RRC entity in the UE and the eNodeB to ensure protocol state consistency.
Principal RRC Specification Reference
Protocol layer where timers reside
Primary configuration delivery methods
Tuning & Optimization
Operators often set timers like T310 higher in rural areas to allow for slow fading recovery, while in urban high-load scenarios, shorter timers trigger faster handovers or re-establishment to maintain throughput.
Critical Delta Focus
Setup Success
HO Continuity
Drop Rate/RLF
Beam Stability