5G NR RRC Timers

5G NR Quick Reference                            

Timers

Timer	Start	Stop	At expiry
T300	Upon transmission of RRCSetupRequest.	Upon reception of RRCSetup or RRCReject message, cell re-selection and upon abortion of connection establishment by upper layers.	Perform the actions as specified in 5.3.3.7.
T301	Upon transmission of RRCReestabilshmentRequest	Upon reception of RRCReestablishment or RRCSetupmessage as well as when the selected cell becomes unsuitable	Go to RRC_IDLE
T302	Upon reception of RRCReject while performing RRC connection establishment or resume, upon reception of RRCRelease with waitTime.	Upon entering RRC_CONNECTED or RRC_IDLE, upon cell re-selection and upon reception of RRCReject message.	Inform upper layers about barring alleviation as specified in 5.3.14.4
T304	Upon reception of RRCReconfiguration message including reconfigurationWithSync	Upon successful completion of random access on the corresponding SpCell For T304 of SCG, upon SCG release	For T304 of MCG, in case of the handover from NR or intra-NR handover, initiate the RRC re-establishment procedure; In case of handover to NR, perform the actions defined in the specifications applicable for the source RAT. For T304 of SCG, inform network about the reconfiguration with sync failure by initiating the SCG failure information procedure as specified in 5.7.3.
T310	Upon detecting physical layer problems for the SpCell i.e. upon receiving N310 consecutive out-of-sync indications from lower layers.	Upon receiving N311 consecutive in-sync indications from lower layers for the SpCell, upon receiving   RRCReconfiguration with reconfigurationWithSync for that cell group, and upon initiating the connection re-establishment procedure. Upon SCG release, if the T310 is kept in SCG.	If the T310 is kept in MCG: If AS security is not activated: go to RRC_IDLE else: initiate the connection re-establishment procedure. If the T310 is kept in SCG, Inform E-UTRAN/NR about the SCG radio link failure by initiating the SCG failure information procedure as specified in 5.7.3.
T311	Upon initiating the RRC connection re-establishment procedure	Upon selection of a suitable NR cell or a cell using another RAT.	Enter RRC_IDLE
T319	Upon transmission of RRCResumeRequestor RRCResumeRequest1.	Upon reception of RRCResume,RRCSetup, RRCRelease, RRCRelease with suspendConfig or RRCReject message, cell re-selection and upon abortion of   connection establishment by upper layers.	Perform the actions as specified in 5.3.13.5.
T320	Upon reception of t320 or upon cell (re)selection to NR from another RAT with validity time configured for dedicated priorities (in which case the remaining validity time is applied).	Upon entering RRC_CONNECTED, upon reception of RRCRelease, when PLMN selection is performed on request by NAS, when the UE enters RRC_IDLE from RRC_INACTIVE, or upon cell (re)selection to another RAT (in which case the timer is carried on to the other RAT).	Discard the cell reselection priority information provided by dedicated signalling.
T321	Upon receiving measConfig including a reportConfig with the purpose set to reportCGI	Upon acquiring the information needed to set all fields of cgi-info, upon receiving measConfig that includes removal of the reportConfig with the purpose set to reportCGI and upon detecting that a cell is not broadcasting SIB1.	Initiate the measurement reporting procedure, stop performing the related measurements.
T322	Upon receving measConfig including reportConfigNRwith the purpose set to reportSFTD and drx-SFTD-NeighMeas is set to true.	Upon acquiring the SFTD measurement results, upon receiving measConfig that includes removal of the reportConfig with the purpose   set to reportSFTD.	Initiate the measurement reporting procedure, stop performing the related measurements.
T325	Upon reception of RRCRelease message with deprioritisationTimer.		Stop deprioritisation of all frequencies or NR signalled by RRCRelease.
T342	Upon transmitting UEAssistanceInformation message with DelayBudgetReport.	Upon initiating the connection   re-establishment/resume procedures, and upon receiving delayBudgetReportingConfig set to release.	No action.
T345	Upon transmitting UEAssistanceInformationmessage with overheatingAssistance	Upon initiating the connection re-establishment procedure and upon initiating the connection resumption procedure	No action.
T380	Upon reception of t380 in RRCRelease.	Upon reception of RRCResume, RRCSetup or RRCRelease.	Perform the actions as specified in 5.3.13.
T390	When access attempt is barred at access barring check for an Access Category. The UE maintains one instance of this timer per Access Category.	Upon cell (re)selection, upon entering RRC_CONNECTED, upon reception of RRCReconfiguration including reconfigurationWithSync, upon change of PCell while in RRC_CONNECTED, upon reception of MobilityFromNRCommand, or upon reception of RRCRelease.	Perform the actions as specified in 5.3.14.4.

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5G NR RRC Timers

5G NR Quick Reference                            

Timers

Timer	Start	Stop	At expiry
T300	Upon transmission of RRCSetupRequest.	Upon reception of RRCSetup or RRCReject message, cell re-selection and upon abortion of connection establishment by upper layers.	Perform the actions as specified in 5.3.3.7.
T301	Upon transmission of RRCReestabilshmentRequest	Upon reception of RRCReestablishment or RRCSetupmessage as well as when the selected cell becomes unsuitable	Go to RRC_IDLE
T302	Upon reception of RRCReject while performing RRC connection establishment or resume, upon reception of RRCRelease with waitTime.	Upon entering RRC_CONNECTED or RRC_IDLE, upon cell re-selection and upon reception of RRCReject message.	Inform upper layers about barring alleviation as specified in 5.3.14.4
T304	Upon reception of RRCReconfiguration message including reconfigurationWithSync	Upon successful completion of random access on the corresponding SpCell For T304 of SCG, upon SCG release	For T304 of MCG, in case of the handover from NR or intra-NR handover, initiate the RRC re-establishment procedure; In case of handover to NR, perform the actions defined in the specifications applicable for the source RAT. For T304 of SCG, inform network about the reconfiguration with sync failure by initiating the SCG failure information procedure as specified in 5.7.3.
T310	Upon detecting physical layer problems for the SpCell i.e. upon receiving N310 consecutive out-of-sync indications from lower layers.	Upon receiving N311 consecutive in-sync indications from lower layers for the SpCell, upon receiving   RRCReconfiguration with reconfigurationWithSync for that cell group, and upon initiating the connection re-establishment procedure. Upon SCG release, if the T310 is kept in SCG.	If the T310 is kept in MCG: If AS security is not activated: go to RRC_IDLE else: initiate the connection re-establishment procedure. If the T310 is kept in SCG, Inform E-UTRAN/NR about the SCG radio link failure by initiating the SCG failure information procedure as specified in 5.7.3.
T311	Upon initiating the RRC connection re-establishment procedure	Upon selection of a suitable NR cell or a cell using another RAT.	Enter RRC_IDLE
T319	Upon transmission of RRCResumeRequestor RRCResumeRequest1.	Upon reception of RRCResume,RRCSetup, RRCRelease, RRCRelease with suspendConfig or RRCReject message, cell re-selection and upon abortion of   connection establishment by upper layers.	Perform the actions as specified in 5.3.13.5.
T320	Upon reception of t320 or upon cell (re)selection to NR from another RAT with validity time configured for dedicated priorities (in which case the remaining validity time is applied).	Upon entering RRC_CONNECTED, upon reception of RRCRelease, when PLMN selection is performed on request by NAS, when the UE enters RRC_IDLE from RRC_INACTIVE, or upon cell (re)selection to another RAT (in which case the timer is carried on to the other RAT).	Discard the cell reselection priority information provided by dedicated signalling.
T321	Upon receiving measConfig including a reportConfig with the purpose set to reportCGI	Upon acquiring the information needed to set all fields of cgi-info, upon receiving measConfig that includes removal of the reportConfig with the purpose set to reportCGI and upon detecting that a cell is not broadcasting SIB1.	Initiate the measurement reporting procedure, stop performing the related measurements.
T322	Upon receving measConfig including reportConfigNRwith the purpose set to reportSFTD and drx-SFTD-NeighMeas is set to true.	Upon acquiring the SFTD measurement results, upon receiving measConfig that includes removal of the reportConfig with the purpose   set to reportSFTD.	Initiate the measurement reporting procedure, stop performing the related measurements.
T325	Upon reception of RRCRelease message with deprioritisationTimer.		Stop deprioritisation of all frequencies or NR signalled by RRCRelease.
T342	Upon transmitting UEAssistanceInformation message with DelayBudgetReport.	Upon initiating the connection   re-establishment/resume procedures, and upon receiving delayBudgetReportingConfig set to release.	No action.
T345	Upon transmitting UEAssistanceInformationmessage with overheatingAssistance	Upon initiating the connection re-establishment procedure and upon initiating the connection resumption procedure	No action.
T380	Upon reception of t380 in RRCRelease.	Upon reception of RRCResume, RRCSetup or RRCRelease.	Perform the actions as specified in 5.3.13.
T390	When access attempt is barred at access barring check for an Access Category. The UE maintains one instance of this timer per Access Category.	Upon cell (re)selection, upon entering RRC_CONNECTED, upon reception of RRCReconfiguration including reconfigurationWithSync, upon change of PCell while in RRC_CONNECTED, upon reception of MobilityFromNRCommand, or upon reception of RRCRelease.	Perform the actions as specified in 5.3.14.4.

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5G NR (SIB-1 TO SIB -9) System information blocks

System information blocks

 

SIB1

SIB1 contains information relevant when evaluating if a UE is allowed to access a cell and defines the scheduling of other system information.It also contains radio resource configuration information that is common for all UEs and barring information applied to the unified access control.

Signalling radio bearer: N/A

RLC-SAP: TM

Logical channels: BCCH

Direction: Network to UE

SIB2

SIB2 contains cell re-selection information common for intra-frequency, inter-frequency and/or inter-RAT cell re-selection.

 (i.e. applicable for more than one type of cell re-selection but not necessarily all) as well as intra-frequency cell re-selection information other than neighbouring cell related.

SIB3

SIB3 contains neighbouring cell related information relevant only for intra-frequency cell re-selection. The IE includes cells with specific re-selection parameters as well as blacklisted cells.

SIB4

     

SIB4 contains information relevant only for inter-frequency cell re-selection i.e. information about other NR frequencies and inter-frequency neighbouring cells relevant for cell re-selection. The IE includes cell re-selection parameters common for a frequency as well as cell specific re-selection parameters.

 SIB5

SIB5 contains information relevant only for inter-RAT cell re-selection i.e. information about E-UTRA frequencies and E-UTRAs neighbouring cells relevant for cell re-selection. The IE includes cell re-selection parameters common for a frequency.

SIB6

SIB6 contains an ETWS primary notification.

SIB7

SIB7 contains an ETWS secondary notification.

SIB8

SIB8 contains a CMAS notification.

SIB9

SIB9 contains information related to GPS time and Coordinated Universal Time (UTC). The UE may use the parameters provided in this system information block to obtain the UTC, the GPS and the local time.

NOTE:    The UE may use the time information for numerous purposes, possibly involving upper layers e.g. to assist GPS initialisation, to synchronise the UE clock.