Timers in GSMTimers in GSM

22-07-200722-07-2007

T3212T3212

This is call periodic This is call periodic location update location update timer.timer.

This parameter is This parameter is sent to MS via sent to MS via system information system information 3.3.

This timer should This timer should be less than the be less than the value set in MSC.value set in MSC.

Default Value is Default Value is 10. That is one 10. That is one hour.hour.

T3212T3212 Time in minutesTime in minutes

0No need for periodic location

update.

1 6

2 12

.. …

255 1530

T3122T3122

When the network receives the When the network receives the channel request sent from MS, if channel request sent from MS, if there is no proper channel to be there is no proper channel to be assigned to MS, the network sends assigned to MS, the network sends the instant assignment rejection the instant assignment rejection message to MS. To avoid the further message to MS. To avoid the further congestion of radio channels congestion of radio channels caused by constant channel caused by constant channel requests from MS, the timer requests from MS, the timer parameter T3122 is included in the parameter T3122 is included in the instant assignment rejection instant assignment rejection message, i.e., the so called wait-for message, i.e., the so called wait-for indication message unit. After MS indication message unit. After MS receives the instant assignment receives the instant assignment rejection message, the new call can rejection message, the new call can be made only after the time be made only after the time indicated by T3122.indicated by T3122.

Note that this parameter is not Note that this parameter is not broad cast in system information.broad cast in system information.

Default Value is 10. That is ten Default Value is 10. That is ten seconds.seconds.

T3212T3212 Time in secondsTime in seconds

0 0

1 1

2 2

.. …

255 255

T3101T3101

Conditions of starting a Conditions of starting a timer: timer:

When BSC sends an When BSC sends an IMMEDIATE ASSIGNMENT IMMEDIATE ASSIGNMENT COMMAND message, Timer COMMAND message, Timer (T3101) is initiated.(T3101) is initiated.

Conditions of ceasing a Conditions of ceasing a timertimer

When the ESTABLISH When the ESTABLISH INDICATION message from INDICATION message from MS is received, Timer T3101 MS is received, Timer T3101 ceases.ceases.

Time-out actionTime-out action When T3101 times out, BSC When T3101 times out, BSC

sends a CHANNEL sends a CHANNEL RELEASE message to BTS.RELEASE message to BTS.

Default Value is 30. That is Default Value is 30. That is three seconds.three seconds.

T3101T3101 Time in secondsTime in seconds

10 1

11 1.1

12 1.2

.. …

50 5

T3103T3103

Timer T3103 supervises the handover Timer T3103 supervises the handover process inside BSC.process inside BSC.

Conditions of starting a timerConditions of starting a timer When BSC sends the HANDOVER When BSC sends the HANDOVER

COMMAND message to MS, the timer COMMAND message to MS, the timer (T3103) is initiated.(T3103) is initiated.

Conditions of ceasing a timerConditions of ceasing a timerWhen BSC receives the HANDOVER When BSC receives the HANDOVER COMPLETE message from MS on the COMPLETE message from MS on the new channel or the HANDOVER new channel or the HANDOVER FAILURE message from MS on the old FAILURE message from MS on the old channel, the timer T3103 ceases.channel, the timer T3103 ceases.

Time-out actionTime-out actionWhen T3103 times out, a CLEAR When T3103 times out, a CLEAR REQUEST message is sent to MSC. REQUEST message is sent to MSC. The new channel is released. The new channel is released.

When configuring this timer, T3103 < When configuring this timer, T3103 < T10 has to be taken into account T10 has to be taken into account

Default value -60 ( Means 6 sec)Default value -60 ( Means 6 sec)

T3103T3103Time in Time in

secondsseconds

35 3.5

36 3.6

37 3.7

.. …

100 10

T3107T3107

T3107 serves to supervise the T3107 serves to supervise the assignment process and the intra-cell assignment process and the intra-cell handover process (< T10).handover process (< T10).

Conditions of starting a timerConditions of starting a timer W hen BSC sends theRIL3_RR W hen BSC sends theRIL3_RR ASSIGNMENT COMMAND message to ASSIGNMENT COMMAND message to MS, the timer (T3107) is initiated.MS, the timer (T3107) is initiated.

Conditions of ceasing a timerConditions of ceasing a timer When BSC receives the RIL3_RR When BSC receives the RIL3_RR ASSIGNMENT COMPLETE message or ASSIGNMENT COMPLETE message or the RIL3_RR ASSIGNMENT FAILURE the RIL3_RR ASSIGNMENT FAILURE message, T3107 ceases.message, T3107 ceases.

Time-out actionTime-out action When T3107 times out, if it belongs to When T3107 times out, if it belongs to assignment process, new/old channels assignment process, new/old channels are released, connections to MS are are released, connections to MS are cleared, a BSSAP ASSIGNMENT cleared, a BSSAP ASSIGNMENT FAILURE message is sent to MSC, it FAILURE message is sent to MSC, it belongs to intra-cell handover process, a belongs to intra-cell handover process, a CLEAR REQUEST message is sent to CLEAR REQUEST message is sent to MSC.MSC.

Default value -60 ( Means 6 sec)Default value -60 ( Means 6 sec)

When configuring this timer, T3107 < When configuring this timer, T3107 < T10 has to be taken into account.T10 has to be taken into account.

T3107T3107Time inTime in

secondsseconds

35 3.5

36 3.6

37 3.7

.. …

100 10

T3109T3109

T3109 supervises channel T3109 supervises channel release process.release process.

Conditions of starting a timerConditions of starting a timerW hen BSC sends the RIL3_RR W hen BSC sends the RIL3_RR CHANNEL RELEASE message CHANNEL RELEASE message to MS, the timer (T3109) is to MS, the timer (T3109) is initiated.initiated.

Conditions of ceasing a timerConditions of ceasing a timerW hen BSC receives the W hen BSC receives the RELEASE INDICATION from RELEASE INDICATION from BTC (when BTS receives the BTC (when BTS receives the DISC frame from MS), T3109 DISC frame from MS), T3109 ceases.ceases.

Time-out actionTime-out actionWhen T3109 times out, BSC When T3109 times out, BSC sends the CHANNEL RELEASE sends the CHANNEL RELEASE message to BTS.message to BTS.

Default value -120 ( Means 12 Default value -120 ( Means 12 sec)sec)

T3109T3109Time inTime in

secondsseconds

80 8.0

81 8.1

82 8.2

.. …

150 15

T10T10

Conditions of starting a timerConditions of starting a timerWhen a ASSIGNMENT COMMAND When a ASSIGNMENT COMMAND message is sent to MS, T10 is initiated.message is sent to MS, T10 is initiated.

Conditions of ceasing a timerConditions of ceasing a timerWhen MS receives the ASSIGNMENT When MS receives the ASSIGNMENT COMPLETE and ASSIGNMENT COMPLETE and ASSIGNMENT FAILURE messages, T10 ceases.FAILURE messages, T10 ceases.

Time-out actionTime-out actionWhen T10 times out, BSC sends the When T10 times out, BSC sends the BSSAP ASSIGNMENT FAILURE BSSAP ASSIGNMENT FAILURE message to MSC.message to MSC.

Default value -80 ( Means 8sec)Default value -80 ( Means 8sec)

T10T10Time inTime in

secondsseconds

40 4.0

41 4.1

42 4.2

.. …

140 14

T7T7 T7 monitors the frequency of the BSSAP T7 monitors the frequency of the BSSAP

HANDOVER REQUIRED message, the time HANDOVER REQUIRED message, the time of the COMMAND message. The long time to of the COMMAND message. The long time to await from when BSC sends out "BSSAP await from when BSC sends out "BSSAP HANDOVER REQIURED" to when MSC HANDOVER REQIURED" to when MSC sends back "BSSAP HANDOVER sends back "BSSAP HANDOVER COMMAND" In failure case, if MSC sends COMMAND" In failure case, if MSC sends BSC the BSSAP HANDOVER REQUIRED BSC the BSSAP HANDOVER REQUIRED REJECT message, it will also enable BSC to REJECT message, it will also enable BSC to stop the T7 timer stop the T7 timer

Conditions of ceasing a timerConditions of ceasing a timerWhen BSC sends the BSSAP HANDOVER When BSC sends the BSSAP HANDOVER REQIURED message to MSC, T7 is initiated. REQIURED message to MSC, T7 is initiated.

Conditions of ceasing a timerConditions of ceasing a timerReceive the BSSAP HANDOVER COMMAND Receive the BSSAP HANDOVER COMMAND or BSSAP HANDOVER REQUIRED REJECT or BSSAP HANDOVER REQUIRED REJECT messages from MSC. When receiving the messages from MSC. When receiving the BSSAP HANDOVER REQUIRED REJECT BSSAP HANDOVER REQUIRED REJECT message, BSC can send other BSSAP message, BSC can send other BSSAP HANDOVER REQIURED messages to MSC. HANDOVER REQIURED messages to MSC.

Time-out actionTime-out actionIf T7 times out and external handover If T7 times out and external handover conditions are still satisfied, BSC will instantly conditions are still satisfied, BSC will instantly repeat the HANDOVER REQUIRED process. repeat the HANDOVER REQUIRED process.

Default value -200 ( Means 20sec)Default value -200 ( Means 20sec)

T7T7Time inTime in

secondsseconds

50 5.0

51 5.1

52 5.2

.. …

300 30

T9101T9101

Conditions of starting a timer: W hen BSC Conditions of starting a timer: W hen BSC sends the BSSAP CLEAR COMPLETE sends the BSSAP CLEAR COMPLETE message to MSC, the timer T9101 is message to MSC, the timer T9101 is initiated.initiated.

Conditions of ceasing a timer: When Conditions of ceasing a timer: When receiving the RLSD message from MSC, receiving the RLSD message from MSC, the timer T9101 ceases.the timer T9101 ceases.

Time-out action: When the timer T9101 Time-out action: When the timer T9101 times out, BSC releases the SCCP times out, BSC releases the SCCP connection by sending the RLSD message.connection by sending the RLSD message.

T9103T9103

Conditions of starting a timer: When BSC Conditions of starting a timer: When BSC sends the CHANNEL ACTIVATION sends the CHANNEL ACTIVATION message to BTS, Timer (rmsT9103) is message to BTS, Timer (rmsT9103) is initiated.initiated.

Conditions of ceasing a timer: W hen BSC Conditions of ceasing a timer: W hen BSC receives the CHANNEL ACTIVATION ACK receives the CHANNEL ACTIVATION ACK or CAHNNEL ACTIVATION NACK or CAHNNEL ACTIVATION NACK messages from BSC, rmsT9103 is initiated.messages from BSC, rmsT9103 is initiated.

Time-out action: When rmsT9103 times Time-out action: When rmsT9103 times out, BSC sends the RF CHANNEL out, BSC sends the RF CHANNEL RELEASE message to BTS.RELEASE message to BTS.

T9104T9104

Conditions of starting a timer: When Conditions of starting a timer: When BSC sends the CLEAR REQUEST BSC sends the CLEAR REQUEST message to MSC, the timer (T9104) message to MSC, the timer (T9104) is initiated.is initiated.

Conditions of ceasing a timer: When Conditions of ceasing a timer: When receiving the CLEAR COMMAND receiving the CLEAR COMMAND message from MSC, the timer T9104 message from MSC, the timer T9104 ceases.ceases.

Time-out action: When T9104 times Time-out action: When T9104 times out, the CLEAR REQUEST message out, the CLEAR REQUEST message is retransmitted (maximally four is retransmitted (maximally four times).times).

T9105 T9105

Conditions of starting a timer: W hen BSC Conditions of starting a timer: W hen BSC sends the SCCP_CONNECTION_REQ sends the SCCP_CONNECTION_REQ message to MSC, the timer (T9105) is message to MSC, the timer (T9105) is initiated.initiated.

Conditions of ceasing a timer: When BSC Conditions of ceasing a timer: When BSC receives the receives the SCCP_CONNECTION_CONFIRM or SCCP_CONNECTION_CONFIRM or SCCP_CONNECTION_REFUSED SCCP_CONNECTION_REFUSED messages from MSC, T9105 ceases.messages from MSC, T9105 ceases.

Time-out action: When T9105 times out, Time-out action: When T9105 times out, BSC sends the CHANNEL RELEASE BSC sends the CHANNEL RELEASE message to MS.message to MS.

T9108T9108

Conditions of starting a timer: When Conditions of starting a timer: When BSC sends the PHYSICAL BSC sends the PHYSICAL CONTEXT REQUEST message to CONTEXT REQUEST message to MS, the timer (T9108) is initiated.MS, the timer (T9108) is initiated.

Conditions of ceasing a timer: When Conditions of ceasing a timer: When BSC receives the PHYSICAL BSC receives the PHYSICAL CONTEXT CONFIRM message from CONTEXT CONFIRM message from BTS, T9108 ceases.BTS, T9108 ceases.

Time-out action: When timer (T9108) Time-out action: When timer (T9108) times out, BSC sends the times out, BSC sends the ASSIGNMENT FAILURE message ASSIGNMENT FAILURE message to MSC.to MSC.

T9113T9113

Conditions of starting a timer: W hen BSC Conditions of starting a timer: W hen BSC sends the HANDOVER REQUEST ACK sends the HANDOVER REQUEST ACK message to MSC, the timer (T9113) is message to MSC, the timer (T9113) is initiated.initiated.

Conditions of ceasing a timer: When BSC Conditions of ceasing a timer: When BSC receives the HANDOVER COMPLETE receives the HANDOVER COMPLETE message from MS or the CLEAR message from MS or the CLEAR COMMAND message from MSC, T9113 COMMAND message from MSC, T9113 ceases.ceases.

Time-out action: When T9113 times out, Time-out action: When T9113 times out, BSC sends the CLEAR REQUEST BSC sends the CLEAR REQUEST message to MSC.message to MSC.

T3111T3111

After releasing the service channel, the delay to the After releasing the service channel, the delay to the deactivation of RF channel intends to spare a period of deactivation of RF channel intends to spare a period of time to repeat the possible channel disconnection.time to repeat the possible channel disconnection.

(Time the network waits after disconnecting the signaling (Time the network waits after disconnecting the signaling link before deactivating the channel)link before deactivating the channel)

Conditions of starting a timer: Conditions of starting a timer: If it is unnecessary to release the A interface connection, If it is unnecessary to release the A interface connection,

when BSC receives the RELEASE INDICATION when BSC receives the RELEASE INDICATION message, the timer T3111 is initiated. If it is unnecessary message, the timer T3111 is initiated. If it is unnecessary to release the A interface connection, when BSC receives to release the A interface connection, when BSC receives the BSSAP CLEAR COMMAND message from MS, the the BSSAP CLEAR COMMAND message from MS, the timer T3111 is initiated.timer T3111 is initiated.

Conditions of ceasing a timerConditions of ceasing a timer T3111 often times out.T3111 often times out. Time-out actionTime-out action When T3111 times out, the RF CHANNEL RELEASE When T3111 times out, the RF CHANNEL RELEASE

message is sent to BTS.message is sent to BTS.