13 Timers and counters

04.603GPPGeneral Packet Radio Service (GPRS)Mobile Station (MS) - Base Station System (BSS) interfaceRadio Link Control / Medium Access Control (RLC/MAC) protocolRelease 1999TS

The tables in sub-clause 13.1 and 13.2 specifies the timers used in RLC/MAC protocol signalling. The denotation of columns is defined as follows:

timer ::= name of the timer;

started ::= under which conditions the timer is started;

stopped ::= under which conditions the timer is stopped;

action at expiry ::= which actions the GPRS entity shall perform at expiry;

value ::= the duration between setting the timer and expiry of the timer ("s" denotes
"second(s)" "xx – yy" means that any value between xx and yy is permitted).

13.1 Timers on the Mobile Station side

Table 13.1.1: Specification of timers used in GPRS on the Mobile Station 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)

T3162

On receipt of a PACKET QUEUING NOTIFICATION

On receipt of a PACKET UPLINK ASSIGNMENT

Abort Packet access procedure; indicate Packet access failure to upper layers and Return to packet idle mode listening to its paging subchannel

5 sec

T3164

On receipt of a PACKET UPLINK ASSIGNMENT

At sending of the first RLC/MAC block

See sub-clause 7.1.4.

5 sec

T3166

At sending of the first RLC/MAC block at one phase access

On receipt of a PACKET UPLINK ACK/NACK

Immediately stop transmitting on the assigned TBF; a TBF establishment failure has occurred or the contention resolution procedures has failed

5 sec

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

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

T3174

On receipt of a PACKET CELL CHANGE ORDER message

On receipt of a response to CHANNEL REQUEST or PACKET CHANNEL REQUEST in the new cell

Return to old cell and send PACKET CELL CHANGE FAILURE

15 sec

T3176

Expiry of T3174

After sending of PACKET CELL CHANGE FAILURE message

Stop cell change order failure procedure.

5 sec

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)

T3180

When transmitting an RLC/MAC block to the network

When detecting an assigned USF value on assigned PDCH

Abnormal release with access retry

5 sec

T3182

After sending the last data block (with CV = 0), or Upon detecting a transmit window stall condition

On receipt of the PACKET UPLINK ACK/NACK message

Abnormal release with access retry

5 sec

T3184

On receipt of a PACKET UPLINK ACK/NACK message

On receipt of PACKET UPLINK ACK/NACK message
(T3184 is also restarted)

Abnormal release with access retry

5 sec

T3186

When packet access procedure is started

Stopped when receiving any message from the network in response to the PACKET CHANNEL REQUEST message or after M+1 attempts to send PACKET CHANNEL REQUEST messages on the PRACH channel

Abort Packet access procedure; indicate Packet access failure to upper layers and return to Packet Idle mode.

5 sec

T3188

If a new fixed allocation has been requested, when all data has been sent on the assigned allocation

On receipt of PACKET UPLINK ASSIGNMENT, PACKET UPLINK ACK/NACK message containing a fixed allocation, or PACKET ACCESS REJECT

Abnormal release with access retry

5 sec

T3190

At reception of a downlink assignment message

Restarted on receipt of data on the resources

Abnormal release without retry

5 sec

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

T3200

On receipt of an RLC/MAC control block containing a segment of an RLC/MAC control message

On receipt of an RLC/MAC control block containing a segment of an RLC/MAC control message such that the mobile station now has the complete control message

Discard and ignore all segments of the partially received RLC/MAC control message

see sub-clause 9.1.11b

T3204

The first attempt to send a PACKET CHANNEL REQUEST during a packet access procedure. The PACKET CHANNEL REQUEST was attempted indicating ‘Single block without TBF establishment’ and the purpose of the packet access procedure is to send a PACKET PAUSE message.

Upon receipt of a PACKET UPLINK ASSIGNMENT.

The packet pause procedure (sub-clause 7.6) is aborted

1 sec

T3158: Wait for sending measurement reports for network controlled cell reselection.

This timer is used on the mobile station side to define the period for performing NC-measurements and send measurement reports in either packet idle or packet transfer mode (see 3GPP TS 05.08).

T3162: Wait for Packet Uplink Assignment after reception of Packet Queuing Notification

This timer is used on the mobile station side after received Packet Queuing Notification to define when to stop waiting for a Packet Uplink Assignment.

T3164: Wait for Uplink State Flag After Assignment

This timer is used on the mobile station side to define when to stop waiting for the USF determining the assigned portion of the uplink channel and repeat the procedure for random access. In multislot operation, it is enough that the assigned USF is noted on one of the uplink PDCHs. This timer is not used when fixed allocations are assigned.

T3166: 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.

T3168: Wait for Packet Uplink Assignment message

This timer is used on the mobile station side to define when to stop waiting for a Packet Uplink Assignment message after sending of a Packet Resource request message or a PACKET CONTROL ACKNOWLEDGEMENT message requesting new TBF.

T3170: Wait for Packet Uplink Assignment after having done (M+1) Packet Channel Requests or after reception of a PACKET ACCESS REJECT message.

This timer is used on the mobile station side when having made M + 1 attempts to send a Packet Channel Request or after reception of a PACKET ACCESS REJECT message. At expiry of timer T3170, the mobile station shall abort the packet access procedure,indicate a packet access failure to upper layer and return to packet idle mode.

The value of this timer is equal to the time taken by T+2S TDMA frames, T and S are defined in sub-clause 7.1.2.1.1.

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.

T3174: Wait for response on new cell after Packet Cell Change Order.

This timer is used on the mobile station side on receipt of a PACKET CELL CHANGE ORDER message. The timer is stopped upon successful access on the new cell. On expiry, the mobile station returns to the old cell and send PACKET CELL CHANGE FAILURE message.

T3176: Stop Cell Change failure procedure.

This timer started when T3174 expires. The timer is stopped upon transmission of the PACKET CELL CHANGE FAILURE message. On expiry, the mobile station stops attempting to send the PACKET CELL CHANGE FAILURE message.

T3178: Wait for sending extended measurement reports.

This timer is used on the mobile station side to define the period for performing extended measurements and send extended measurement reports in packet idle mode (see 3GPP TS 05.08).

T3180: Wait for Uplink State Flag After Data Block

This timer is used on the mobile station side to define when to stop waiting for the USF determining the assigned portion of the uplink channel after the pervious RLC/MAC block is sent. In multislot operation, it is enough that the assigned USF is noted on one of the uplink PDCHs. If expired, the mobile station repeats the procedure for random access. This timer does not apply to fixed allocation transfers.

T3182: Wait for Acknowledgement

This timer is used on the mobile station side to define when to stop waiting for temporary Packet Uplink Ack/Nack after the last RLC data block has been sent for the current send window or for the entire Temporary Block Flow.

T3184: No Ack/Nack Received

At fixed allocation, this timer is used on the mobile station side to decide when to stop waiting for a Packet Uplink Ack/Nack. (This timer does not apply to mobiles performing a dynamic allocation transfer).

At exclusive allocation, this timer is used to detect a radio link failure condition. If expired, the mobile station performs an abnormal release with access retry.

T3186: Supervision of the random access procedure

This timer is used on the mobile station side to define the maximum allowed time to repeat the sending of all PACKET CHANNEL REQUEST messages. At expiry of timer T3186, the Packet Uplink establishment procedure is aborted.

T3188: Allocation Exhausted

This timer is used on the mobile station side to decide when to stop waiting to receive additional resources from the network. (This timer does not apply to a mobile performing a dynamic allocation transfer).

T3190: Wait for Valid Downlink Data Received from the Network

This timer is used on the mobile station side to stop waiting for the valid data from the network side either following the initial Packet Downlink Assignment or after some previous downlink RLC/MAC block.

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.

T3200 RLC/MAC control message reassembly guard

T3200 is used by the mobile station to control when it will discard segments of a partially received RLC/MAC control message. The mobile station shall have one instance of timer T3200 for each segmented RLC/MAC control message that the mobile station is capable of receiving in parallel.

T3204: Wait for Packet Uplink Assignment after the first attempt to send a Packet Channel Request during a packet access procedure. The Packet Channel Request was attempted indicating ‘Single block without TBF establishment’ and the purpose of the packet access procedure is to send a PACKET PAUSE message.

This timer is used by a mobile station with non-GSM capabilities to stop waiting for a PACKET UPLINK ASSIGNMENT message. At expiry of timer T3204, the Packet Pause procedure (sub-clause 7.6) is aborted.

13.2 Timers on the network side

Table 13.2.1: Specification of timers used in GPRS 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

Stopped when the network establishes a new downlink TBF.

Restarted at the reception of the final PACKET DOWNLINK ACK/NACK or PACKET CONTROL ACKNOWLEDGEMENT.

The network releases TFI resource

Greater than T3192

T3195

If counter N3105 = N3105_MAX

None

The network releases TFI resources.

5 sec

T3169: Wait for Reuse of USF and TFI after the mobile station uplink assignment is invalid

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.

Its value is network dependent. The value of T3169 should be greater than T3180, T3182 and (for exclusive allocation) T3184.

T3191: Wait for reuse of TFI after sending of the last RLC Data 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.

Its value is network dependent.

T3193: 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.

Its value is network dependent.

T3195: 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.

Its value is network dependent.

13.3 Counters on the Mobile Station side

N3102 At each cell reselection the mobile station shall set the counter N3102 to the value defined by the optional broadcast parameter PAN_MAX. Whenever the mobile station receives a Packet Ack/Nack that allows the advancement of V(S), the mobile station shall increment N3102 by the broadcast value PAN_INC, however N3102 shall never exceed the value PAN_MAX. Each time T3182 expires the mobile station shall decrement N3102 by the broadcast value PAN_DEC. When N3102 ≤ 0 is reached, the mobile station shall perform an abnormal release with cell re-selection.

N3104 When the mobile station sends the first RLC/MAC block the counter N3104 shall be initialized to 1. For each new RLC/MAC block the mobile station sends it shall increment N3104 by 1 until the first correct PACKET UPLINK ACK/NACK message is received. Then N3104 shall not be further incremented. If the N3104 counter is equal to N3104_MAX and no correct PACKET UPLINK ACK/NACK message has been received, the contention resolution fails and the mobile station behaves as specified in sub-clause 7.1.2.3.

N3104_MAX shall have the value:

N3104_MAX = 3 * (BS_CV_MAX + 3) * number of uplink timeslots assigned.

13.4 Counters on the Network side

N3101: When the network after setting USF, receives a valid data block from the mobile station, it will reset counter N3101. The network will increment counter N3101 for each USF for which no data is received. N3101max shall be greater than 8.

N3103: N3103 is reset when transmitting the final PACKET UPLINK ACK/NACK message within a TBF (final ack indicator set to 1). If the network does not receive the PACKET CONTROL ACKNOWLEDGEMENT message in the scheduled block, it shall increment counter N3103 and retransmit the PACKET UPLINK ACK/NACK message. If counter N3103 exceeds its limit, the network shall start timer T3169.

N3105: When the network after sending a RRBP field in the downlink RLC data block , receives a valid RLC/MAC control message from the mobile station, it will reset counter N3105. The network will increment counter N3105 for each allocated data block for which no RLC/MAC control message is received. The value of N3105max is network dependent.

Annex A (informative):
Bibliography

1) ITU-T I.130, Method for the Characterization of Telecommunication Services Supported by an ISDN

2) ITU-T Q.65, Stage 2 of the Method for Characterization of the Services Supported by an ISDN

3) DIS 8886, OSI Data Link Service Definition

4) DIS 10022, OSI Physical Service Definition

5) ISO 10039, Medium Access Control Service Definition

6) ISO 4335, HDLC Procedures

7) ISO 7478, Multilink Procedures

8) ISO 7498, OSI Basic Reference Model and Layer Service Conventions

Annex B (informative):
RLC data block delimitation examples