Terminology » GSM » GSM Timers on Mobile Side

GSM Timers on Mobile Side

gsm mobile communication timer protocol network

This page details the timers used in GSM on the mobile side, including T3110, T3112, T3114, T3122, T3128, T3130, T3142, T3148, T3164, T3204, T3206, T3208, T3210, T3220, T3222, T3224, and T3232.

GSM Timers and their Functions

TimerFunction/Value
T3110This timer delays the channel de-activation after receiving a channel release message. It allows time for complete disconnection of the signaling link. The timer value is set so that two DISC frames can be transmitted when the mobile doesn’t receive an answer from the network.
T3112Used by a VGCS mobile when receiving segmented RP-Data messages on the SACCH. Started when receiving the first segment of a segmented RP-Data message for a group call the MS is a member of, for which no previous segment has been received. It is stopped in these situations:
  • The MS receives the complete RP-Data message
  • The MS discards the message as a result of timer T3114 expiring for some other message
  • The MS deletes the segment(s) (with SMS reference number n) because it has received a segment with an SMS reference number which is more than 4 higher (modulo 16) than that of the message corresponding to this timer
  • The MS changes its channel
  • The voice group call is cleared.
The value of the timer is 20 seconds.
T3114Used by a VGCS mobile when receiving a complete RP-Data message on the SACCH that isn’t the next in sequence message that should be sent to the upper layer. It is stopped in these situations:
  • The MS delivers the RP-Data message to the upper layer
  • The MS changes its channel
  • The voice group call is cleared.
The value of the timer is 10 seconds.
T3122Used during random access or dedicated channel assignment while in packet transfer mode, after receiving an immediate assignment reject. The value is given by the network and conveyed in the message.
T3128Started when the mobile station starts the uplink (UL) investigation procedure when the UL is busy. It stops upon receiving the first UL free message. When it expires, the UL investigation procedure is aborted. This timer value is about 1 second.
T3130Started after sending the first UPLINK ACCESS message during a VGCS uplink access procedure, or sending the first PRIORITY UPLINK REQUEST message during a VGCS priority uplink request procedure. It is stopped upon receiving a VGCS UPLINK GRANT message. It can be started a maximum of 3 times. On expiry of timer T3130 for the third time a rejection of the uplink request is indicated to the upper layers. The value of this timer is set to 5 seconds.
T3142Used during packet access on the CCCH and during packet access while in dedicated mode. It is started after receiving an IMMEDIATE ASSIGNMENT REJECT or a DTM REJECT message. The timer value is provided by the network, either in the immediate assignment reject or using the DTM reject message.
T3148Used during DTM establishment in dedicated mode. It is started after sending a DTM REQUEST message during a packet access procedure while in dedicated mode. It is stopped upon receiving one of the following messages:
  • DTM ASSIGNMENT COMMAND
  • PACKET ASSIGNMENT
  • DTM REJECT
  • ASSIGNMENT COMMAND
  • HANDOVER COMMAND
The packet access procedure is aborted when it expires. The timer value is 4 seconds.
T3164Used for packet access procedure using CCCH. It starts when the mobile receives an immediate assignment message. It stops when an RLC/MAC block is transmitted on the assigned TBF. When it expires, the mobile station returns to IDLE mode. The timer value is 5 seconds.
T3204Used by a mobile station with non-GSM capabilities. The timer is started after sending the first CHANNEL REQUEST during a packet access procedure. The CHANNEL REQUEST was sent requesting a single block packet access and the purpose of the packet access procedure is to send a PACKET PAUSE message. It is stopped upon receiving an IMMEDIATE ASSIGNMENT message granting a single block period on an assigned packet uplink resource. The packet access procedure is aborted when the timer expires. Value: 1 second.
T3206Used by a VGCS mobile when receiving segmented notifications on the NCH. The timer is started when receiving a segment of a segmented notification for a group call that the MS is a member of for which no previous segment has been received. It is stopped in these situations:
  • The MS receives the second segment
  • The MS joins another call
  • The value of NLN changes
  • The MS reselects to another cell.
The value of the timer is 5 seconds.
T3208Used by a VGCS mobile when receiving segmented notifications on the FACCH. The timer is started when receiving the first segment of a segmented notification for a group call that the MS is a member of for which no previous segment has been received. It is stopped in these situations:
  • The MS receives the complete message
  • The MS joins another call
  • The MS performs Handover to another cell.
The value of the timer is 1 second.
T3210Used by a VGCS mobile when receiving segmented notifications on the PCH. The timer is started when receiving the first segment of a segmented notification for a group call that the MS is a member of for which no previous segment has been received. It is stopped in these situations:
  • The MS receives the complete message
  • The MS leaves Idle mode
  • Notifications for another group call are received on the PCH
The value of the timer is 5 seconds.
T3220Used by an MBMS capable mobile station when receiving pre-notification of an MBMS session. The timer is started when receiving a PAGING REQUEST message containing an MBMS pre-notification that the mobile station shall receive. It is stopped upon receiving a PAGING REQUEST message containing a notification of the same session as when starting this timer, or if any other RR procedure on CCCH not related to MBMS is triggered or a notification is received for a higher priority session while the timer is running. At expiry, the mobile station returns to DRX mode unless it is engaged in any other MBMS session and then stays in broadcast/multicast receive mode. The value of the timer is 46 seconds.
T3222An instance of the timer may be used by an MBMS capable mobile station in dedicated mode during the notification of MBMS. An instance of this timer may be started upon receiving an MBMS ANNOUNCEMENT message when in dedicated mode. The instance of this timer is stopped when the mobile enters packet idle mode. At expiry of an instance of this timer, the mobile station discards the MBMS related information stored upon receipt of the corresponding MBMS ANNOUNCEMENT message.
T3224The timer starts on receipt of a VGCS_UPLINK_GRANT message aimed at another mobile station. It is stopped when the mobile station receives an UPLINK BUSY message. At expiry, the mobile station shall follow the same procedures as for expiry of timer T3130. The value of the timer is 1 second.
T3232The timer is used to control the length of the non-DRX mode period in which the mobile station is acquiring an ETWS Primary Notification message. It is started upon receiving a first PAGING REQUEST TYPE 1 message containing a valid segment of an ETWS Primary Notification message. It is stopped in these situations:
  • The mobile station receives the complete ETWS Primary Notification message
  • Upon initiating cell reselection or connection establishment procedures
The timer is restarted if the mobile station receives an indication of a new ETWS Primary Notification message prior to acquiring a complete ETWS Primary Notification message. At expiry the mobile station shall discard all segments of the partially received ETWS Primary Notification message and re-enter DRX mode. Timer value: 5 seconds.