01 ra1736en90gls00 0002 appendix sbs timers

Appendix - SBS Timers

RA1736EN90GLS00_0002 © 2007 Nokia Siemens Networks

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Contents 1 BSS timers 3 1.1 BSSMAP timers 4 1.2 LAPD timers 9 1.3 Radio resource timers 10 1.4 RLC/MAC timers 14 1.5 Other timers 18



RA1736EN90GLS00_0002© 2007 Nokia Siemens Networks

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1 BSS timers



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1.1 BSSMAP timers The BSSMAP Timers are specified by GSM 08.08-850. Table GSM 08.08-850: List of Timers in the BSSMAP Procedures Timer Title Time T1 Time to receipt of BLOCKING ACKNOWLEDGE at the BSS O&M

T2 Reset guard period at the MSC O&M

T4 Time to receipt of RESET ACKNOWLEDGE at the BSS O&M

T5 Overload timer in the MSC O&M

T6 Overload timer in the MSC O&M

T7 Handover required periodicity O&M

T8 Time to receipt of successful handover information O&M

T10 Time to return of ASSIGNMENT COMPLETE or ASSIGNMENT FAILURE from MS (note)

O&M

T11 Maximum allowed queuing time for assignment O&M

T12 Time to receipt of RESET CIRCUIT ACKNOWLEDGE at the MSC O&M

T13 Reset guard period at the BSS O&M

T16 Time to receipt of RESET ACKNOWLEDGE at the MSC O&M

T17 Overload timer in the BSS O&M

T18 Overload timer in the BSS O&M

T19 Time to receipt of RESET CIRCUIT ACKNOWLEDGE at the BSS O&M

T20 Time to receipt of CIRCUIT GROUP BLOCKING ACKNOWLEDGE at the BSS..

O&M

T21 Time to receipt of BLOCKING ACKNOWLEDGE at the MSC O&M

T22 Time to receipt of CIRCUIT GROUP BLOCKING ACKNOWLEDGE at the MSC

O&M

Tqho Maximum allowed queuing time for handover O&M

NOTE: T10 is not the same as T3107 as defined in GSM 04.08



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SBS Timers The BSC (BSSMAP) Timers can be configured with the command SET BSC PKGBSCT:NAME=BSC:bscn,BSCTX=<TX>.

• BSCT1 Time to receive a blocking acknowledge. The value must be higher than the MSC maximum reaction time and the transmission time for the blocking/unblocking and the belonging acknowledge message. The MSC choose the terrestrial resources to be used. The MSC therefore needs to be informed of any terrestrial circuits that are out of service at the BSS. This is performed by using a simple blocking/unblocking procedure. The timer T1 watches over the reception of the Blocking/Unblocking Acknowledge message from the MSC. After a first T1 expiration the BSS repeats the Blocking/Unblocking message. After a second expiration the BSS marked the belonging circuits as blocked without waiting for the acknowledge. The Default value is 6 seconds.

• BSCT3 Period of RecourceIndication message. The Default value is 25 seconds.

• BSCT4 Time to receive a Reset Acknowledge. The value of T4 must be higher than the value of the MSC timer T2 plus the transmission time of the Reset and the Reset Acknowledge messages. The timer watches over the reception of a Reset Acknowledge message from the MSC in reaction of a transmitted Reset message. The Default value is 30 seconds.



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• BSCT7 Period of „HandoverRequired“ message. Purpose: Minimum time for HANDOVER REQUIRED messages for the

same connection. Start: Sending of HANDOVER REQUIRED by BSC. Stop: HANDOVER COMMAND received reason for handover has

disappeared communication with MS is lost transaction has ended, call cleared.

Action expiry: Repetition of HANDOVER REQUIRED. If the BSS has detected that a radio reason exist for a handover to occur or the MSC has initiated a handover candidate inquiry procedure, the BSS sends a HANDOVER REQUIRED message to the MSC (see 08.08 cap. 3.1.5.1.). The updated message shall be repeated by the BSS with a periodicity of T7 until: - A handover command message is received, or; - A reset message is received, or; - The reason for the original handover required message disappears e.g. the MS transmission improves, or; - All communication is lost with the MS as defined in rec. 04.08, and the transaction is abandoned, or; - The transaction ends, e.g. call clearing. The Default value is 2 seconds.

• BSCT8 Time to receipt „HandoverSuccessful“ message. In the SBS this timer is also used for intra BSC Handover. Therefore this timer is implemented different from GSM. The counter will also be stopped for Handover Complete messages. Purpose: Keep the old channel sufficient long to be able to return to it,

and to release the channels if the MS is lost. Start: Reception of HANDOVER COMMAND at BSC. Stop: Reception of CLEAR COMMAND from MSC or HANDOVER

COMPLETE or HANDOVER FAILURE from MS at BTS. Action expiry: Release of old channels. T8 is defined as the time that BSC layer 3 will wait for a handover to complete before releasing the source channel. This is the sum of the time for all messages to be sent to the mobile plus the time to access a target and come back (if necessary). The Default value is 5 seconds.



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• BSCT10 Time to return „AssignmentComplete“ message This timer is started by the sending of an „AssignmentCommand“ message and is normally stopped when the MS has correctly seized the new channels (when receiving the „AssignmentComplete“ message from the MS). Its purpose is to keep the old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. The value must be higher than the maximum transmission time of the „AssignmentCommand“ and the „AssignmentComplete“ message plus the maximum duration of an attempt to establish a data link multiframe mode. The Default value is 5 seconds.

• BSCT11 Maximum allowed queuing time. The Default value is 8 seconds.

• BSCT13 Reset guard period at the BSC. The timer T13 is a guard timer which is started after the reception of a Reset message. It gives time for the BSS to release all affected calls and to erase all affected references. After expiration of T13 the BSS sends a Reset Acknowledge message to the MSC. The value of T13 must be higher than the time needed by the BSS to release all affected calls and to erase all affected references. To speed up the complete Reset procedure the timer T13 shall be as short as possible. The value of the „Wait for Acknowledge timer“ T16 in the MSC must be higher than the value of T13 plus the transmission time of the Reset and the Reset Acknowledge message. The Default value is 25 seconds.

• BSCT17 Overload Timer. When getting informed on an overload situation in the MSC the BSC performs the first step for originating traffic reduction, the overload level is set to 1 and the BSC starts the timers T17 and T18 with T18 > T17. During run time of T17 all overload messages with the same cause as the initializing message are ignored in order not to reduce the traffic too rapidly. If the overload situation is still present after expiry of T17, but during runtime of T18, the next step of traffic reduction is initiated, overload level is incremented and T17 and T18 are started again. This step by step reduction of traffic is maintained until the maximum reduction is obtained arriving at the last step. If no further overload message is received from the MSC, the expiry of timer T18 triggers the decrease of the load level by one step. When the overload level reaches the value 0 and the timer T18 expires, the MSC overload is cleared. The Default value is 10 seconds.



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• BSCT18 Overload timer. See description of T17. The Default value is 30 seconds.

• BSCT19 Time to receipt „ResetCircuitAcknowledge“ message at the BSS. The Default value is 6 seconds.

• BSCT20 Maximum allowed queuing time for handover. The Default value is 6 seconds.

• BSCTQHO Maximum allowed queuing time for handover. The Default value is 10 seconds.



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1.2 LAPD timers SBS Timers The following LAPD Timers can be configured with the command SET BTS PKGBTST: NAME=BTS:btsn,TX=<TX>..

• TSYNC This attribute defines the timer value which is used by the BTS to supervise time-out of TRAU frame handling .This timer is used only if a BTS-TRAU traffic connection is already established. It is started after three TRAU-frames have not been received again . If it expires a connection failure indication is reported to the BSC .The default value is 10 seconds.

• TTRAU This attribute defines the timer value which is used by the BTS to supervise time-out of TRAU datalink (traffic) at connection establishment or handover . It is set with sending the first TRAU data frame uplink and cleared when the first frame downlink arrives . If it expires a connection failure indication will be reported to the BSC .The default value is 10 seconds.

• T200A This attribute contains values for the LapDm Timer 200, to be used on the different control channels. Default values: sdcchSAPI0 220ms facchTCHF 155ms facchTCHH 205ms sacchTCHSAPI0 900ms sacchSDCCH 900ms sdcchSAPI3 450ms sacchTCHSAPI3 1350ms



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1.3 Radio resource timers The Timers for Radio Resource Management are specified by GSM 04.18-850. Table GSM 04.18-850: Timers for Radio Resource Management Network SIde T3101 This timer is started when a channel is allocated with an IMMEDIATE

ASSIGNMENT message. It is stopped when the MS has correctly seized the channels. Its value is network dependent. NOTE: It could be higher than the maximum time for a L2 establishment attempt.

T3103 This timer is started by the sending of a HANDOVER message and is normally stopped when the MS has correctly seized the new channel. Its purpose is to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the HANDOVER COMMAND, plus the value of T3124, plus the maximum duration of an attempt to establish a data link in multiframe mode.)

T3105 This timer is used for the repetition of the PHYSICAL INFORMATION message during the hand-over procedure. Its value is network dependent. NOTE: This timer may be set to such a low value that the message is in fact continuously transmitted.

T3107 This timer is started by the sending of an ASSIGNMENT COMMAND or a DTM ASSIGNMENT COMMAND message and is normally stopped when the MS has correctly seized the new RR channels. Its purpose is to keep the old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the ASSIGNMENT COMMAND message plus twice the maximum duration of an attempt to establish a data link multiframe mode.

T3109 This timer is started when a lower layer failure is detected by the network, when it is not engaged in a RF procedure. It is also used in the channel release procedure. Its purpose is to release the channels in case of loss of communication. Its value is network dependent. NOTE: Its value should be large enough to ensure that the MS detects a radio link failure.

T3111 This timer is used to delay the channel deactivation after disconnection of the main signaling link. Its purpose is to let some time for possible repetition of the disconnection. Its value is equal to the value of T3110.



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Table GSM 04.18-850: List of Timers for Radio Resource Management (cont.) T3113 This timer is started when the network has sent a PAGING REQUEST

message and is stopped when the network has received the PAGING RESPONSE message. Its value is network dependent. NOTE: The value could allow for repetitions of the Channel Request message and the requirements associated with T3101.

T3115 This timer is used for the repetition of the VGCS UPLINK GRANT message during the uplink access procedure. Its value is network dependent. NOTE: This timer may be set to such a low value that the message is in fact continuously transmitted.

T3117 This timer is started by the sending of a PDCH ASSIGNMENT COMMAND message and is normally stopped when the MS has correctly accessed the target TBF. Its purpose is to keep the old channel sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the PDCH ASSIGNMENT COMMAND message plus T3132 plus the maximum duration of an attempt to establish a data link in multiframe mode.

T3119 This timer is started by the sending of a RR-CELL CHANGE ORDER message and is normally stopped when the MS has correctly accessed the new cell. Its purpose is to keep the old channels sufficiently long for the MS to be able to return to the old channels, and to release the channels if the MS is lost. Its value is network dependent. NOTE: It could be higher than the maximum transmission time of the RR_CELL CHANGE ORDER, plus T3134, plus the maximum duration of an attempt to establish a data link in multiframe mode.

T3141 This timer is started when a temporary block flow is allocated with an IMMEDIATE ASSIGNMENT message during a packet access procedure. It is stopped when the mobile station has correctly seized the temporary block flow. Its value is network dependent.

Ny1 The maximum number of repetitions for the PHYSICAL INFORMATION message during a handover. The value is network dependent.

Ny2 The maximum number of repetitions for the VGCS UPLINK GRANT message during an uplink access procedure. The value is network dependent.



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SBS Timers The Timers for Radio Resource Management can be configured with the command SET BTS PKGBTST: NAME=BTS:btsn,TX=<TX>..

• T3101 Timer is used for channel allocation with the „Immediate Assignment“ message. After sending an „Immediate Assignment“ message to the MS, the BSS starts timer T3101 to guard the seizure of the reserved channel. The timer is stopped when the MS has correctly seized the channel. If timer T3101 elapses before the main Signaling link is established, the newly allocated channel is released and the channel request is forgotten by the BSS. The default value is 3 seconds.

• T3103 Timer is used with the „Handover Command“ message. Purpose: to keep the old channels sufficiently long for the MS to be

able to return to the old channels, and to release the channels if the MS is lost.

Start: Transmission of HANDOVER COMMAND by BTS. Stop: Receiption of HANDOVER COMPLETE or HANDOVER

FAILURE at BTS. Action expiry: All channels to this MS are released because the MS is

lost with a high probability. This Timer is not used in the SBS. Timer T8 is used.

• T3105 Timer is used for the repetition of the „Physical Information“ message. Purpose: Period for repetition of PHYSICAL INFORMATION. Start: Sending of PHYSICAL INFORMATION by BTS. Stop: Receiption of correctly decoded signaling or TCH frame

on new channel from MS t BTS. Action expiry: Repetition of PHYSICAL INFORMATION; if the maximum

number of repetitions has been reached: release of new channel.

The Timer T3105 is used for the repetition of the „Physical Information“ during the handover procedure between non synchronized cells. After receipt of „Handover Access“ bursts with a correct handover reference the BSS sends a „Physical Information“ message to the MS and starts timer T3105. If the timer expires before the BSS receives any correct frame from the MS, it repeats the „Physical Information“ and restarts T3105. After receiving a correct frame from the MS the BSS resets T3105.The maximum number of repetition will be NY1. If this number is reached, the newly allocated channels are released and the context related to the handover is stopped. The default value is 80 milliseconds.



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• T3107 Timer is used with the „Assignment Command“ message. The purpose of the timer T3107 is to keep the old channel sufficiently long for the MS to be able to return to the old channel, and to release the channel if the MS is lost. After sending an „Assignment Command“ or „Channel Mode Modify“ message to the MS the BSS starts T3107.At receipt of the „Assignment Command“ or „Channel Mode Modify Acknowledge“ message from the MS, the BSS releases the previously allocated resources and stops timer T3107. It sends an „Assignment Complete“ message to the MSC. When receiving an „Assignment Failure“ message the BSS stops T3107 and forwards the message to the MSC with the cause „radio interface failure - reversion to old channel“. If T3107 elapses before a message from the MS is received, all channels for this MS are released. The BSS sends an „Assignment Failure“ message with cause „radio interface failure“ message to the MSC. This Timer is not used in the SBS. Timer T10 is used.

• T3109 Timer is used in case of lower layer failures .The purpose of T3109 is to release the channel in case of loss of communication. The timer is used during the Channel Release Procedure which is initiated by the MSC for dedicated channel releases or by the BSS after O&M intervention or at Radio Link Failure conditions. After receipt of a „Clear Command“ message from the MSC or a detection of a lower layer failure the BSS sends a „Channel Release“ message to the MS, deactivates the SACCH and starts T3109. After confirmation by a DISC frame from the MS, the BSS resets T3109. If T3109 expires, the BSS deactivates all channels for this MS. The default value is 12 seconds.

• T3111 The timer T3111 is used to delay the channel deactivation after disconnection of the main Signaling link. Its purpose is to let some time for possible repetition of the disconnection. After receipt of a DISC frame from the MS, the BSS confirms the release of the main Signaling link towards the MS, stops timer T3109 and starts timer T3111. Upon expiry of T3111, the BSS deactivates the channels, they are then free to be allocated to another connection. The BSS sends a „Clear Complete“ message to the MSC. The default value is 0,5 seconds.

• T3122 This timer is located on the MS side and sets the MS (Mobile Station) waiting time before attempting another channel request after reception of the IMMEDIATE ASSIGNMENT REJECT message. Its value is given by the network in the IMMEDIATE ASSIGN REJECT message. The default value is 5 seconds.



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1.4 RLC/MAC timers The Timers for RLC/MAC are specified by GSM 04.60-870. Table GSM 04.60-870: Configurable timers of RLC/MAC on the MS side Timer started stopped action at expiry value T3158 Started when ordered

by a NETWORK_CONTROL_ORDER and then restarted each time a Network Controlled (NC) Measurement is performed in MM Ready state and in packet idle or packet transfer mode

See 05.08 Restart the timer, perform the measurement and send a NC Measurement report. The timer shall be restarted with either of the parameters NC_REPORTING_PERIOD_I when in packet idle mode or with the parameter NC_REPORTING_PERIOD_T when in packet transfer mode

Defined by the parameter or by a random value (see 3GPP TS 05.08)

T3168 At sending the PACKET RESOURCE REQUEST message, Channel Request Description IE in PACKET DOWNLINK ACK/NACK or the PACKET CONTROL ACKNOWLEDGEMENT message requesting new TBF.

On receipt of a PACKET UPLINK ASSIGNMENT message

Reinitiate the packet access procedure or retransmit the PACKET RESOURCE REQUEST or PACKET DOWNLINK ACK/NACK

assigned in system information

T3170 After having made M + 1 attempts to send a PACKET CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST message, or on receipt of a PACKET ACCESS REJECT message.

On receipt of a PACKET UPLINK ASSIGNMENT or PACKET QUEUING NOTIFICATION message

Abort Packet access procedure; indicate a packet access failure to upper layer and return to packet idle mode.

Defined by parameters TX_INT and S



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Timer started stopped action at expiry value T3172 On receipt of a PACKET

ACCESS REJECT message

On receipt of a PACKET UPLINK ASSIGNMENT message

Packet Access in the cell no longer prohibited

assigned in message

T3178 Started when ordered by a EXT_MEASUREMENT_ORDER and then restarted each time an extended (EXT) Measurement is performed in packet idle mode

See 05.08 Restart the timer, perform the measurement and send an EXT Measurement report. The timer shall be restarted with the parameter EXT_REPORTING_PERIOD

Defined by the parameter or by a Random value (see 3GPP TS 05.08)

T3192 At sending the PACKET DOWNLINK ACK/NACK with the Final Ack Indicator=1, or at sending the PACKET CONTROL ACK as a response to final RLC data block in unacknowledged mode.

Restarted at sending the PACKET DOWNLINK ACK/NACK with the Final Ack Indicator=1, or at sending the PACKET CONTROL ACK as a response to final RLC data block in unacknowledged mode. Stopped at the reception of a PACKET DOWNLINK ASSIGNMENT or PACKET TIMESLOT RECONFIGURE.

Release the resources, stop monitoring the PDCHs, and begin to monitor the paging channel

assigned in system information



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Table GSM 04.60-870: Timers of RLC/MAC on the Network side Timer started Stopped action at expiry typical

value T3169 If counter N3101 =

N3101_MAX, or if counter N3103 = N3103_MAX

None The network releases USF and TFI resources.

5 sec

T3191 When the last RLC data block is sent with the FBI bit set to ‘1’

When the final PACKET DOWNLINK ACK/NACK or PACKET CONTROL ACKNOWLEDGEMENT is received Restarted at the transmission of an RLC data block with the FBI bit set to ‘1’.

The network releases TFI resource.

5 sec

T3193 When the final PACKET DOWNLINK ACK/NACK or PACKET CONTROL ACKNOWLEDGEMENT is received

When the network establishes a new downlink TBF.

The network releases TFI resource

greater than T3192

T3195 If counter N3105 = N3105_MAX

None The network releases TFI resources.

5 sec

SBS Timers The SBS Timers for RLC/MAC can be configured with the command SET PTPPKF: NAME= PTPPKF: ptppkfn,TX=<TX> and SET PCU: NAME= PCU: pcun,TX=<TX> and

• T3166_68 Wait for Packet Uplink ACK/NACK after sending of first data block. This timer is used on the mobile station side to define when to stop waiting for a Packet Uplink ACK/NACK after sending of the first data block. This value plus one must be multiplied by 500 msec. to obtain the real value used in PSI messages. The default value is 3,5 seconds.

• T3141 This timer is started when a tbf is assigned with an immediate assignment during a packet access procedure; it is stopped when the MS has correctly seized the tbf. The default value is 5 seconds.



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• T3169 This timer defines the waiting time for reuse TFI and USF after the thresholds N3101 and N3103 are reached. This timer is used on the network side to define when the current uplink assignment is surely invalid on the mobile station side so that the assigned USF(s) and TFI can be reused on the uplink. During that period the corresponding USF(s) is not broadcast. The value of T3169 should be greater than T3180, T3182 and (for exclusive allocation) T3184. The default value is 1 seconds.

• T3172 Prohibit packet Access in the cell after Packet Access Reject message has been received. This timer is used on the mobile station side on receipt of a Packet Access Reject message corresponding to one of the mobile station’s 3 last Packet Channel Request messages. If T3172 expires before receiving an assignment message, the mobile station returns to packet idle mode. After T3172 expiry packet Access is no longer prohibited in the cell but no Channel Request message shall be sent as a response to a page until a Paging Request message for the mobile station is received. The default value is 5 seconds.

• T3191 This timer defines the waiting time for reuse TFI and USF after having sent the last RLC block. This timer is used on the network side to define when the current assignment is surely invalid on the mobile station side so that the TFI can be reused. The default value is 5 seconds.

• T3192 Wait for release of the TBF after reception of the final block. This timer is used on the mobile station side when the mobile station has received all of the RLC data blocks. When timer T3192 expires the mobile station shall release the resources associated with the TBF (e.g. TFI) and begin to monitor its paging channel. This parameter is used in the PSI (Packet System Information) messages. If it is set to the 3 value (corresponding to 0 ms), the timer is not started. The default value is 2 seconds.

• T3193 This time-out timer must be set greater than the timer T3192. Wait for reuse of TFI after reception of the final Packet Downlink Ack/Nack from the mobile station. This timer is used on the network side to define when timer T3192 on the mobile station side has surely expired so that the TFI can be reused. The default value is 4 seconds.

• T3195 This Timer assigns the PSI Count High Rate. Wait for reuse of TFI when there is no response from the MS (radio failure or cell change). This timer is used on the network side to define when the current assignment is surely invalid on the mobile station side so that the TFI can be reused. The default value is 1 seconds.



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1.5 Other timers SBS Timers In this section you can find other important timers.

• T3212 (Mobility Management) This timer specifies the interval for the MS periodic location updates. The value zero indicates the MS should not perform any periodic location updates. The default value is 36 minutes.

01 ra1736en90gls00 0002 appendix sbs timers

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