5G Timers | T300,T301,T302,T304,T310,T311,T312 timer at UE

This page on 5G timers mentions UE timers such as T300, T301, T302, T304, T310, T311 and T312 timer used in 5G wireless system for various functions.

5G Timers Function at Start Stop at Expiry
T300 The Timer T300 starts at the transmission of RRC Connection Request It stops at receptionof RRC Connection Setup or RRC Connection Reject message, cell selection • If timer expires, The UE shall reset MAC, release MAC configuration and re-establish RLC for all RBs which are established,
• It informs upper layers about the failure to establish RRC connection, upon which the procedure ends.
T301 The Timer T301 starts at transmission of RRC Connection Re-establishment request. It stops at reception of RRC Connection Re-establishment or RRC Connection Re-establishment Reject message as well as when the selected cell becomes unsuitable due to some reasons. The timer T301 goes to RRC_IDLE state upon expiry.
T302 The Timer T302 starts at reception of RRC Connection Reject while performing RRC Connection Establishment. It stops upon entering RRC_CONNECTED and upon cell selection. At expiry, it (UE) informs upper layers about barring alleviation for mobile originating data or mobile originating access.
T304 The timer T304 starts at reception of RRC Connection Re-configuration message including the Mobility Control Info. message. It stops as per criterion for successful completion of handover within 5GRA, handover to 5GRA. At expiry, in case of intra 5GRA handover, it initiates RRC connection re-establishment procedure.
T310 The timer T310 starts upon detecting physical layer problems for PCell i.e. upon receiving N310 consecutive out-of-sync indications from lower layers. It stops upon receiving N311 consecutive in-sync indications from lower layers for PCell, upon triggering the handover procedure and upon initiating the connection re-establishment procedure. At expiry, IF security is not activated "it does to RRC_IDLE state"
ELSE "it initiates connection establishment procedure"
T311 The timer T311 starts upon initiating the RRC Connection re-establishment procedure. It stops upon selection of a suitable 5GRA cell. At expiry the timer enters in RRC_IDLE state.
T312 The timer T312 starts upon triggering a measurement report for measurement identity for which T312 has been configured while T310 timer is running. • It stops upon receiving N311 consecutive in-sync indications from lower layers
• upon triggering the handover procedure
• upon initiating connection re-establishment procedure and
• upon the expiry of T310 timer.
At expiry, IF security is not activated "the timer goes to RRC_IDLE state"
ELSE "it initiates the connection re-establishment procedure"

GSM Timers | WCDMA Timers | LTE Timers

Following links are on useful GSM timers, WCDMA timers and LTE timers other than 5G timers mentioned on this page.
•  GSM Timers
•  WCDMA Timers
•  GSM MS Timers
•  GSM BTS Timers
•  LTE Timers

5G NR Numerology | 5G NR Terminology

5G NR Control channels | 5G NR Traffic Channels | 5G NR Reference Signals and sequences


This 5G tutorial also covers following sub topics on the 5G technology:
5G basic tutorial
5G Frequency Bands
5G millimeter wave tutorial
5G mm wave frame
5G millimeter wave channel sounding
Difference between 4G and 5G
5G testing and test equipments
5G network architecture
5G NR Physical layer
5G NR MAC layer
5G NR RLC layer
5G NR PDCP layer

RF and Wireless Terminologies