5G NR中RRC的计时器（定时器）、计数器和常量

5G NR网络无线资源控制(RRC)中引入了下列计时器、计数器和常量，以便UE在RRC setuprequest, RRC reestablishment, RRC resume, RRC suspend等进程的可靠运行。

一、   RRC计时器

指示计时器持续时间及在事件中何时开始和停止；如果计时器超时，UE将采取的行动。这些计时器由字母“T”表示，后跟3位数字，例如 T300。每个计时器起始值为零；UE应用的计时器值倒计数为零时，则计为超时；除非明确说明另有规定。

1.1        Timer: T300

Ø Start Point:（起始点）

Upon transmission of RRC Setup Request

Ø Stop Point:（结束点）

Upon reception of RRC Setup or RRC Reject message

Upon Cell re-selection

Upon abortion of connection establishment by    upper layers

Ø Action upon Timer Expiry:（超时后续动作）

1.2        Timer: T301

Ø Start Point:（起始点）

Upon transmission of RRC Reestabilshment Request

Ø Stop Point:（结束点）

Upon reception of RRC Reestablishment or RRC Setup message

when the selected cell becomes unsuitable

Ø Action upon Timer Expiry:（超时后续动作）

Go to RRC-IDLE

1.3        Timer: T302

Ø Start Point:（起始点）

Upon reception of RRC Reject while    performing RRC connection establishment or resume

Upon reception of RRC Release with    wait Time

Ø Stop Point:（结束点）

Upon entering RRC-CONNECTED or RRC-IDLE

Upon cell re-selection

Upon reception of RRC Reject message

Ø Action upon Timer Expiry:（超时后续动作）

Inform upper layers about barring    alleviation

1.4        Timer: T304

Ø Start Point:（起始点）

Upon detecting physical layer problems for    the SpCell i.e. upon receiving N310 consecutive    out-of sync indications from lower layers

Ø Stop Point:（结束点）

Upon receiving N311 consecutive in-sync indications    from lower layers for the SpCell,

Upon receiving RRC Reconfiguration with    reconfiguration With Sync for that cell group, and upon initiating the    connection re-establishment procedure.

Upon SCG release, if the T310 is    kept in SCG

Ø Action upon Timer Expiry:（超时后续动作）

If the T310 is kept in MCG: If    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 of specification 38.331

1.5        Timer: T311

Ø Start Point:（起始点）

Upon initiating the RRC connection reestablishment procedure

Ø Stop Point:（结束点）

Upon selection of a suitable NR cell    or a cell using another RAT

Ø Action upon Timer Expiry:（超时后续动作）

Enter RRC_IDLE

1.6        Timer: T319

Ø Start Point:（起始点）

Upon transmission of RRC Resume Request

Ø Stop Point:（结束点）

Upon reception of RRC Resume, RRCSetup,    RRC Release, RRC Release with suspend Config or RRC Reject message, cell    re-selection

Upon abortion of connection establishment by    upper layers

Ø Action upon Timer Expiry:（超时后续动作）

Perform the actions as specified in 5.3.13.5 of    3GPP specification 38.331

1.7        Timer: T320

Ø Start Point:（起始点）

Upon reception of t320

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)

Ø Stop Point:（结束点）

Upon entering RRC-CONNECTED,

Upon reception of RRC Release,    when PLMN selection is performed on request by NAS

Upon cell (re)selection to another RAT (in    which case the timer is carried on to the other RAT)

Ø Action upon Timer Expiry:（超时后续动作）

Discard the cell re-selection priority    information provided by dedicated signalling

1.8        Timer: T321

Ø Start Point:（起始点）

Upon receiving measConfig including    a reportConfig with the purpose set to report CGI

Ø Stop Point:（结束点）

Upon acquiring the information needed to set    all fields of cgiinfo

Upon receiving measConfig that    includes removal of the reportConfig with the purpose    set to reportCGI

upon detecting that a cell is not    broadcasting SIB1

Ø Action upon Timer Expiry:（超时后续动作）

Initiate the measurement reporting procedure,    stop performing the related measurements and remove the corresponding measId

1.9        Timer: T325

Ø Start Point:（起始点）

Upon reception of RRCRelease message    with deprioritisationTimer

Ø Action upon Timer Expiry:（超时后续动作）

Stop deprioritisation of all  frequencies or NR signalled by RRC Release

1.10    Timer: T380

Ø Start Point:（起始点）

Upon reception of RRC Release including suspendConfig

Ø Stop Point:（结束点）

Upon reception of RRCResume,    RRCSetup or RRC Release

Ø Action upon Timer Expiry:（超时后续动作）

Perform the actions as specified in 5.3.13 of    3GPP 38.331

1.11    Timer: T390

Ø Start Point:（起始点）

When access attempt is barred at    access barring check for an Access Category

The UE shall maintain one instance of this    timer per Access Category

Ø Stop Point:（结束点）

As specified in 5.3.14.3 of 3GPP 38.331

Ø Action upon Timer Expiry:（超时后续动作）

Perform the actions as specified in    5.3.14.4 of 3GPP 38.331

1.12    Timer: T3xx

Ø Start Point:（起始点）

Upon transmitting UEAssistanceInformation message    with DelayBudgetReport

Ø Stop Point:（结束点）

Upon initiating the connection re-establishment    procedures

Ø Action upon Timer Expiry:（超时后续动作）

No action.

二、   RRC常量和计数器：

计数与否或针对特定事件尝试。计数器用字母“n”表示，后面跟着3个数字。例如 n310。

2  2.1  N310: 

Ø Maximum number of consecutive “out-of-sync” indications  for the PCell received from lower layers

Ø  Reset

Ø Upon reception of “insync” indication   from lower layers

Ø  Upon receiving RRCReconfiguration with reconfigurationWithSync for   that cell group

Ø Upon initiating the connection reestablishment   procedure

Ø Incremented

Ø Upon reception of “out-of-sync” from  lower layer while the timer T310 is stopped

Ø When reaching max value

Ø Start timer T310

2.2  N311: 

Ø Maximum number of consecutive “in-sync” indications  for the PCell received from lower layers

Ø Reset

Ø Upon reception of “outof-sync” indication   from lower layers

Ø Upon receiving RRCReconfiguration with reconfigurationWithSync for  that cell group

Ø Upon initiating the connection reestablishment   procedure

Ø Incremented

Ø Upon reception of the “in-sync”from  lower layer while the timer T310 is running

Ø When reaching max value

Ø Stop the timer T310