3.5 RR procedures on CCCH related to temporary block flow establishment

04.183GPPMobile radio interface Layer 3 specificationRadio Resource Control (RRC) protocolRelease 1999TS

The establishment of a temporary block flow (TBF) on a packet data physical channel is supported by procedures on CCCH when PCCCH is not provided in the cell. The procedures for temporary block flow establishment using CCCH are only applicable to a mobile station supporting GPRS. The procedures are optional for the network.

These procedures constitute a complement to the corresponding procedures for temporary block flow establishment using PCCCH, defined in 3GPP TS 04.60, and include the procedures using CCCH for packet paging (sub-clause 3.5.1), packet access (sub-clause 3.5.2) and packet downlink assignment (sub-clause 3.5.3).

3.5.1 Packet paging procedure using CCCH

The network can initiate the packet paging procedure in order to cause upper layers in the mobile station to respond, see clause 4. The packet paging procedure can only be initiated by the network.

3.5.1.1 Packet paging initiation by the network

The packet paging procedure is initiated by the RR entity of the network side. It is triggered by a page request from the MM sublayer, see 3GPP TS 24.007.

The network initiates the paging procedure by sending a paging request message on an appropriate paging subchannel on CCCH or PCCCH. Paging initiation using a paging subchannel on CCCH is used when sending paging information to a mobile station and PCCCH is not present in the cell.

NOTE 1: There are three types of paging request messages that are applicable:

– PAGING REQUEST TYPE 1;

– PAGING REQUEST TYPE 2; and

– PAGING REQUEST TYPE 3.

In a PAGING REQUEST message used for the packet paging procedure, the mobile station shall be identified by the P-TMSI (GPRS TMSI) or its IMSI. If the mobile station is identified by the P-TMSI, it shall proceed as specified in sub-clause 3.5.1.2.

If the mobile station identified by its IMSI, it shall parse the message for a corresponding Packet Page Indication field:

– if the Packet Page Indication field indicates a paging procedure for RR connection establishment, or the field is not present in the message, the mobile station shall proceed as specified in sub-clause 3.3.2.2;

– if the Packet Page Indication field indicates a packet paging procedure, the mobile station shall proceed as specified in sub-clause 3.5.1.2.

A PAGING REQUEST message may include more than one mobile station identification.

The mobile station in packet idle mode is required to receive and analyse the paging messages and immediate assignment messages sent on the paging subchannels on CCCH corresponding to the paging groups determined for it in packet idle mode, as specified in 3GPP TS 05.02. These messages contain a page mode information element.

NOTE 2: The possible immediate assignment messages are: the IMMEDIATE ASSIGNMENT, the IMMEDIATE ASSIGNMENT EXTENDED and the IMMEDIATE ASSIGNMENT REJECT messages.

The treatment of page mode information, including the procedure when the mobile station selects a new PCH, and the procedure if a message in a paging subchannel is not received correctly are defined in sub-clause 3.3.2.1.1.

3.5.1.2 On receipt of a packet paging request

On the receipt of a paging request message, the RR sublayer of addressed mobile station indicates the receipt of a paging request to the MM sublayer, see 3GPP TS 24.007.

3.5.2 Packet access procedure using CCCH

The packet access procedure using CCCH may be used to establish a temporary block flow to support the transfer of LLC PDUs in the direction from the mobile station to the network. Establishment using one phase and two phase packet access, see 3GPP TS 04.60, are supported. The two phase packet access is supported by means of the single block or multiple block packet access option in this procedure, allowing the transfer of a PACKET RESOURCE REQUEST and possibly an ADDITIONAL MS RADIO ACCESS CAPABILITIES message to the network.

The single block packet access option in this procedure may also be used by a mobile station in packet idle mode to transfer an RLC/MAC control message other than the PACKET RESOURCE REQUEST message to the network, see sub-clause 3.5.2.2.

3.5.2.1 Entering the packet transfer mode: packet access procedure

The establishment of an uplink temporary block flow may be initiated by the RR entity of the mobile station using the packet access procedure. The procedure is triggered by a request from upper layers to transfer a LLC PDU, see 3GPP TS 24.007. The request from upper layers specifies radio priority and an RLC mode associated with the packet transfer or it indicates that the packet to be transferred contains signalling.

Upon such a request:

– if access to the network is allowed (sub-clause 3.5.2.1.1), the RR entity of the mobile station initiates the packet access procedure as defined in sub-clause 3.5.2.1.2;

– otherwise, it rejects the request.

If the request from upper layers indicates signalling, the highest radio priority level shall be used at determination if access to the network is allowed, and the acknowledged RLC mode shall be used.

3.5.2.1.1 Permission to access the network

Access to the network is allowed:

– if the mobile station is a member of at least one authorized access class or special access class as defined in sub-clause 3.3.1.1.1; and

– if packet access is allowed in the cell for the radio priority level associated with the packet transfer, as indicated by the PRIORITY_ACCESS_THR parameter broadcast in SI 13 message;

– if the cell belongs to one of the allowed LSAs for the mobile station, as indicated on the SIM, in the case where the mobile station is a LSA only access subscriber.

3.5.2.1.2 Initiation of the packet access procedure: channel request

The mobile station initiates the packet access procedure by scheduling the sending of CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST messages on RACH.

The cause to be used in the CHANNEL REQUEST message for a non-EGPRS TBF mode capable MS or an EGPRS TBF mode capable MS in a non-EGPRS capable cell depends on the purpose of the packet access procedure as follows:

– If the purpose of the packet access procedure is to send user data and the requested RLC mode is unacknowledged mode, the mobile station shall request a single block packet access and attempt a two phase packet access.

– If the purpose of the packet access procedure is to send user data and the requested RLC mode is acknowledged mode, the mobile station shall request either a one phase packet access or a single block packet access.

– If the purpose of the packet access procedure is to send a Page Response, a Cell update (the mobile station was in GMM READY state before the cell reselection) or for any other GPRS Mobility Management or GPRS Session Management procedure, the mobile station shall request a one phase packet access.

– If the purpose of the packet access procedure is to send a Measurement Report, the mobile station shall request a single block packet access.

– If the purpose of the packet access procedure is to send a PACKET PAUSE message, the mobile station shall request a single block packet access. Upon sending the first CHANNEL REQUESTmessage the mobile station shall start timer T3204. If timer T3204 expires before an IMMEDIATE ASSIGNMENT message granting a single block period on an assigned packet uplink resource is received, the packet access procedure is aborted. If the mobile station receives an IMMEDIATE ASSIGNMENT message during the packet access procedure indicating a packet downlink assignment procedure, the mobile station shall ignore the message.

EGPRS TBF mode capable MSs shall monitor the GPRS Cell Options IE on the BCCH (SI13) for the cell’s EGPRS capability. In the GPRS Cell Options IE it is also indicated if the EGPRS PACKET CHANNEL REQUEST is supported in the cell. The following table specifies which message and which establishment cause shall be used by an EGPRS mobile station when accessing an EGPRS capable cell depending on the purpose of the packet access procedure; this table covers the case where PBCCH is not present in the cell (see 3GPP TS 04.60 for the case where PBCCH is present in the cell).

Purpose of the packet access procedure

EGPRS PACKET CHANNEL REQUEST supported in the cell

EGPRS PACKET CHANNEL REQUEST not supported in the cell

User data transfer – requested RLC mode = unacknowledged

EGPRS PACKET CHANNEL REQUEST with access type = ‘Two-phase access’

CHANNEL REQUEST with establishment cause = ‘Single block packet access’ for initiation of a two-phase access

User data transfer – requested RLC mode = acknowledged and number of RLC data blocks ≤ 8 (note 1)

EGPRS PACKET CHANNEL REQUEST with access type = ‘Short Access’ or ‘One-phase access’ or ‘Two-phase access’

CHANNEL REQUEST with establishment cause = ‘Single block packet access’ for initiation of a two-phase access

User data transfer – requested RLC mode = acknowledged and number of RLC data blocks > 8 (note 1)

EGPRS PACKET CHANNEL REQUEST with access type = ‘One-phase access’ or ‘Two-phase access’

CHANNEL REQUEST with establishment cause = ‘Single block packet access’ for initiation of a two-phase access

Upper layer signalling transfer (e.g. page response, cell update, MM signalling, etc)

EGPRS PACKET CHANNEL REQUEST with access type = ‘signalling’ or CHANNEL REQUEST with establishment cause ‘one-phase access’

CHANNEL REQUEST with establishment cause = ‘Single block packet access’ for initiation of a two-phase access or CHANNEL REQUEST with establishment cause value ‘one-phase access’

Sending of a measurement report or of a PACKET CELL CHANGE FAILURE

CHANNEL REQUEST with establishment cause = ‘Single block packet access’

Sending of a PACKET PAUSE message

CHANNEL REQUEST with establishment cause = ‘Single block packet access’ (note 2)

NOTE 1: The number of blocks shall be calculated assuming channel coding scheme MCS-1.

NOTE 2: Upon sending the first CHANNEL REQUESTmessage the mobile station shall start timer T3204. If timer T3204 expires before an IMMEDIATE ASSIGNMENT message granting a single block period on an assigned packet uplink resource is received, the packet access procedure is aborted. If the mobile station receives an IMMEDIATE ASSIGNMENT message during the packet access procedure indicating a packet downlink assignment procedure, the mobile station shall ignore the message.

The mobile station then leaves the packet idle mode. In particular, the mobile station station shall ignore PAGING REQUEST messages indicating a packet paging procedure.

A mobile station belonging to GPRS MS class A or B shall continue to monitor its paging subchannel on CCCH for PAGING REQUEST messages indicating an establishment of RR connection. A mobile station belonging to GPRS MS class B may abort the packet access procedure at the receipt of a PAGING REQUEST messages indicating an establishment of RR connection.

The mobile station schedules CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST messages on RACH as defined in sub-clause 3.3.1.1.2.

The CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST messages are sent on RACH and contain the parameters:

– an establishment cause which indicates packet access, and as applicable, a request for one phase packet access or single block packet access for a CHANNEL REQUEST (sub-clause 9.1.8), or a request for one phase access or two phase access or short access or sending of signalling data for an EGPRS PACKET CHANNEL REQUEST (see 3GPP TS 04.60);

– a random reference which is drawn randomly from an uniform probability distribution for every new transmission.

After sending the first CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST message, the mobile station shall start listening to the BCCH; it shall also listen to the full downlink CCCH timeslot corresponding to its CCCH group. The mobile station shall perform signal strength measurements as they are defined for packet idle mode, see 3GPP TS 05.08.

Having sent the maximum number of CHANNEL REQUEST messages, the mobile station starts timer T3146. At expiry of timer T3146, the packet access procedure is aborted and a packet access failure is indicated to upper layers.

If the mobile station receives an IMMEDIATE ASSIGNMENT message during the packet access procedure indicating a packet downlink assignment procedure, the mobile station shall abort the packet access procedure and respond to the IMMEDIATE ASSIGNMENT message as specified in sub-clause 3.5.3.1.2. The mobile station shall then attempt an establishment of uplink TBF, using the procedure specified in 3GPP TS 04.60 which is applicable in packet transfer mode.

3.5.2.1.3 Packet immediate assignment

3.5.2.1.3.1 On receipt of a CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST message

On receipt of a CHANNEL REQUEST message indicating a packet access, the network may allocate a temporary flow identity and assign a packet uplink resource comprising one PDCH for an uplink temporary block flow in GPRS TBF mode. On receipt of a EGPRS PACKET CHANNEL REQUEST message, the network may allocate a temporary flow identity and assign a packet uplink resource comprising one PDCH for an uplink temporary block flow in EGPRS TBF mode or GPRS TBF mode.

If the establishment cause in the CHANNEL REQUEST message indicates a request for a single block packet access, the network shall grant only the single block period on the assigned packet uplink resource if the network allocates resource for the mobile station. If the establishment cause in the EGPRS PACKET CHANNEL REQUEST message indicates a request for a two phase access, the network shall grant one or two radio blocks for the mobile station (within a Multi Block allocation) to send a PACKET RESOURCE REQUEST and possibly an ADDITIONAL MS RADIO ACCESS CAPABILITIES messages on the assigned packet uplink resource if the network allocates resource for the mobile station.

If the establishment cause in the CHANNEL REQUEST message indicates a request for one phase packet access, the network may grant either a one phase packet access or a single block packet access for the mobile station. If a single block packet access is granted, it forces the mobile station to perform a two phase packet access. If the establishment cause in the EGPRS PACKET CHANNEL REQUEST message indicates a request for one phase packet access, the network may grant either a one phase packet access or a two phase access (within a Multi Block allocation). If a multiple block packet access is granted, it forces the mobile station to perform a two phase packet access.

The packet uplink resource is assigned to the mobile station in an IMMEDIATE ASSIGNMENT message sent in unacknowledged mode on the same CCCH timeslot on which the network has received the CHANNEL REQUEST or the EGPRS PACKET CHANNEL REQUEST message. There is no further restriction on what part of the downlink CCCH timeslot the IMMEDIATE ASSIGNMENT message can be sent. Timer T3141 is started on the network side.

The IMMEDIATE ASSIGNMENT message contains:

– the information field of the CHANNEL REQUEST or the EGPRS PACKET CHANNEL REQUEST message and the frame number of the frame in which the CHANNEL REQUEST or the EGPRS PACKET CHANNEL REQUEST message was received;

– the packet channel description;

– the initial timing advance;

– the packet uplink assignment or EGPRS packet uplink assignment construction.

If frequency hopping is applied, the network may use the indirect encoding or the direct encoding of the frequency configuration in the Packet Channel Description information element. If the indirect encoding is used, the mobile station uses information received in system information or stored from a previous assignment to determine the frequency parameters, see 3GPP TS 04.60. If the direct encoding is used, the mobile station uses the cell allocation defined for the cell to decode the mobile allocation.

If the indirect encoding is used, the IMMEDIATE ASSIGNMENT message may contain a CHANGE_MARK_1 field. If that is present, the mobile station shall verify the validity of the SI13_CHANGE_MARK associated with the GPRS mobile allocation to which the message refers, see 3GPP TS 04.60. If the CHANGE_MARK_1 field and the SI13_CHANGE_MARK do not match, the message does not satisfactorily define a PDCH.

If the mobile station receives an IMMEDIATE ASSIGNMENT message and the Dedicated mode or TBF information element indicates that this is the first message in a two-message assignment, the mobile station shall continue to listen to the full CCCH. The network may send a second IMMEDIATE ASSIGNMENT message to the mobile station within two multiframe periods following the first IMMEDIATE ASSIGNMENT message, specifying the packet channel description and, if required, a mobile allocation for the assignment. The two IMMEDIATE ASSIGNMENT messages in a two-message assignment shall have the same contents of the Request Reference information elements.

If the mobile station does not receive the second IMMEDIATE ASSIGNMENT messages in a two-message assignment within two multiframe periods following the first message, the mobile station shall discard the first IMMEDIATE ASSIGNMENT message received.

On receipt of an IMMEDIATE ASSIGNMENT message or, in case of a two-message assignment, a matching pair of IMMEDIATE ASSIGNMENT messages corresponding to one of its 3 last CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST messages, the mobile station stops T3146 (if running), stops sending CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST messages, and switches to the assigned PDCH.

The content of the packet uplink assignment construction (respectively EGPRS packet uplink assignment construction indicates which type of packet access is granted: one phase packet access or single (respectively multiple) block packet access

3.5.2.1.3.2 One phase packet access

In the case the one phase packet access is granted, the packet uplink assignment construction contains:

– the temporary flow identity;

– the USF value, if the medium access method is dynamic allocation; or
the fixed allocation bitmap, if the medium access method is fixed allocation;

– the channel coding scheme for RLC data blocks;

– the power control parameters;

– the polling bit;

– optionally, the timing advance index (see 3GPP TS 05.10);

– optionally, the TBF starting time (note: TBF starting time is mandatory if medium access method is fixed allocation).

In addition, the EGPRS packet uplink assignment construction also contains :

– the EGPRS modulation and coding scheme;

– information whether retransmitted uplink data blocks shall be resegmented or not;

– the EGPRS window size to be used within the transmission;

– optionally a request for the mobile station to send its radio access capability information.

The medium access method is dynamic allocation or fixed allocation and the RLC mode is acknowledged mode, see 3GPP TS 04.60.

If the medium access method is fixed allocation, and the number of blocks allocated in the ALLOCATION_BITMAP is not sufficient to transfer all the RLC/MAC blocks that the MS has to transmit at the time the packet uplink assignment construction is received, the MS shall request additional resources by sending a PACKET RESOURCE REQUEST on one of the allocated blocks.

If the timing advance index (TAI) is included in the packet uplink assignment construction, the mobile station shall use the continuous update timing advance mechanism, see 3GPP TS 05.10, using PTCCH in the same timeslot as the assigned PDCH. If a timing advance index (TAI) field is not included, the continuous update timing advance mechanism shall not be used.

In case the packet uplink assignment or EGPRS packet uplink assignment construction contains a TBF starting time and the mobile station receives the message before the TBF starting time has expired, it shall wait until the frame number indicated by the TBF starting time before accessing the channel. If the mobile station receives the message after the TBF starting time has expired, it shall ignore the TBF starting time and may immediately access the channel. If the medium access method is dynamic allocation, the mobile station shall start timer T3164. Regardless of which allocation mode is used, the mobile station shall proceed with the contention resolution at one phase access defined in 3GPP TS 04.60.

If the Polling bit is set to 1, MS shall send a PACKET CONTROL ACKNOWLEDGEMENT message (see 3GPP TS 04.60) on the assigned PDCH, in the uplink block specified by the TBF Starting Time. In this case the TBF Starting Time is used both to indicate when the assigned PDCH becomes valid and to specify the uplink block. If the TBF Starting Time is not present or has expired, the MS shall ignore the polling request.

When the mobile station switches to the assigned PDCH, it shall take the power control parameters received in the IMMEDIATE ASSIGNMENT message into account, perform signal strength measurements and apply output power control procedures as they are defined for packet transfer mode, see 3GPP TS 05.08.

When assigning an EGPRS TBF, the network may request information about radio access capabilities of the mobile station on one or several frequency bands within the IMMEDIATE ASSIGNMENT message ; the list of frequency bands is ordered by the network starting with the most important and ending with the least important one. The mobile station shall provide the network with its radio access capabilities for the frequency bands it supports, in the same priority order as the one specified by the network, by sending a PACKET RESOURCE REQUEST message, and an ADDITIONAL MS RADIO ACCESS CAPABILITIES if all the requested informations do not fit in the PACKET RESOURCE REQUEST. If the mobile station does not support any frequency band requested by the network, it shall report its radio access capabilities for the BCCH frequency band. The mobile station shall indicate in the PACKET RESOURCE REQUEST if it will send more information about its radio access capabilities in the ADDITIONAL MS RADIO ACCESS CAPABILITIES message. The PACKET RESOURCE REQUEST and the ADDITIONAL MS RADIO ACCESS CAPABILITIES shall be sent within the one or two first radio blocks allocated for the mobile station on the assigned PDCH.

The network may request a retransmission of the PACKET RESOURCE REQUEST and the ADDITIONAL MS RADIO ACCESS CAPABILITIES messages. A request for retransmission of one or both of these messages shall be indicated in the PACKET UPLINK ACK/NACK message. The mobile station has to indicate within the PACKET RESOURCE REQUEST if the message is a retransmitted one.

3.5.2.1.3.3 Single block packet access

In the case the single block packet access is granted, the packet uplink resource description contains:

– the power control parameter setting;

– the TBF starting time.

If the mobile station receives the IMMEDIATE ASSIGNMENT message before the TBF starting time has expired, it shall wait until the block period indicated by the TBF starting time. The network shall use the TBF starting time to indicate the first frame number belonging to the single block period granted for packet access. The mobile station may either use the assigned block period to send a PACKET RESOURCE REQUEST message to initiate the two phase packet access procedure defined in 3GPP TS 04.60, or to send an RLC/MAC control message other than the PACKET RESOURCE REQUEST message to the network, see sub-clause 3.5.2.2.

If the mobile station receives the IMMEDIATE ASSIGNMENT message after the TBF starting time has expired, a failure has occurred.

If a failure occurs and the packet access attempt was due to a request from upper layers to transfer a LLC PDU, a TBF establishment failure has occurred and the mobile station proceeds as specified in sub-clause 3.5.2.1.5. If a failure occurs and the packet access attempt was due to the sending of an RLC/MAC control message, the packet access is aborted, the mobile station returns to packet idle mode.

3.5.2.1.3.3a Multiblock packet access

In the case the multiblock packet access is granted, the EGPRS packet uplink assignment description contains:

– timeslot number of the allocation and the number of blocks allocated;

– the power control parameter setting;

– the TBF starting time.

When assigning a multiblock packet access, the network may request information about radio access capabilities of the mobile station on one or several frequency bands within the IMMEDIATE ASSIGNMENT message and allocate one or two radio blocks for uplink control messages accordingly ; the list of frequency bands is ordered by the network starting with the most important and ending with the least important one . The mobile station shall then provide the network with its radio access capabilities for the frequency bands it supports, in the same priority order as the one specified by the network, by sending a PACKET RESOURCE REQUEST message in the first radio block on the assigned PDCH, and an ADDITIONAL MS RADIO ACCESS CAPABILITIES immediately after the PACKET RESOURCE REQUEST message on the assigned PDCH if all the requested informations do not fit in the PACKET RESOURCE REQUEST and two radio blocks have been allocated by the network. If the mobile station does not support any frequency band requested by the network, it shall report its radio access capabilities for the BCCH frequency band in the PACKET RESOURCE REQUEST message. The mobile station shall indicate in the PACKET RESOURCE REQUEST if it will send more information about its radio access capabilities in the ADDITIONAL MS RADIO ACCESS CAPABILITIES message. If the mobile station has been allocated two radio blocks and all the requested informations fit in the PACKET RESOURCE REQUEST message, no ADDITIONAL MS RADIO ACCESS CAPABILITIES message shall be sent (see 3GPP TS 04.60). Instead, some uplink control block (e.g. packet measurement report, packet uplink dummy control block) may be sent by the mobile station.

The network may indicate in the next PACKET UPLINK ASSIGNMENT message a request for retransmission of the ADDITIONAL MS RADIO ACCESS CAPABILITIES message (see 3GPP TS 04.60).

If the mobile station receives the IMMEDIATE ASSIGNMENT message before the TBF starting time has expired, it shall wait until the block period indicated by the TBF starting time. The network shall use the TBF starting time to indicate the first frame number belonging to the multi block period granted for packet access. If the mobile station receives the IMMEDIATE ASSIGNMENT message after the TBF starting time has expired, a failure has occurred.

If a failure occurs and the packet access attempt was due to a request from upper layers to transfer a LLC PDU, a TBF establishment failure has occurred and the mobile station proceeds as specified in sub-clause 3.5.2.1.5. If a failure occurs and the packet access attempt was due to the sending of an RLC/MAC control message, the packet access is aborted, the mobile station returns to packet idle mode.

3.5.2.1.3.4 Packet access rejection

The network may send to the mobile station an IMMEDIATE ASSIGNMENT REJECT message in unacknowledged mode on the same CCCH timeslot on which the channel request message was received. There is no further restriction on what part of the downlink CCCH timeslot an IMMEDIATE ASSIGNMENT REJECT message can be sent. This message contains the request reference and a wait indication.

On receipt of an IMMEDIATE ASSIGNMENT REJECT message corresponding to one of its 3 last CHANNEL REQUEST messages, the mobile station stops sending CHANNEL REQUEST messages, starts timer T3142 with the indicated value, ("wait indication" information element), starts T3146 if it has not already been started, and listens to the downlink CCCH until T3146 expires. During this time, additional IMMEDIATE ASSIGNMENT REJECT messages are ignored, but any immediate assignment corresponding to any other of its 3 last CHANNEL REQUEST messages make the mobile station follow the procedure in sub-clause 3.5.2.1.3.1. If no such immediate assignment is received, the mobile station returns to packet idle mode and notify higher layers (TBF establishment failure) and notify higher layers (TBF establishment failure).

If the purpose of the packet access procedure is to send a PACKET PAUSE message and an IMMEDIATE ASSIGNMENT REJECT message is received, the packet access procedure is aborted.

If the mobile station has received responses from the network on all, or in case more than 3 were sent the last 3, of its CHANNEL REQUEST messages, it shall immediately return to packet idle mode and notify higher layers.

The mobile station is not allowed to make a new attempt for packet access in the same cell until T3142 expires, but may attempt packet access in an other cell after successful cell reselection for radio conditions reasons (see 3GPP TS 05.08). The value of the wait indication (i.e. T3142) relates to the cell from which it was received.

The mobile station may initiate RR connection establishment in the same cell before T3142 has expired, see sub-clause 3.3.1.1.3.2.

3.5.2.1.4 Packet access completion

The one phase packet access procedure is completed at a successful contention resolution. The mobile station has entered the packet transfer mode. Timer T3141 is stopped on the network side. Timer T3164 is stopped on the mobile station side.

3.5.2.1.5 Abnormal cases

If a failure occurs on the mobile station side before a successful contention resolution procedure is completed, the allocated temporary block flow is released; the mobile station returns to packet idle mode, upper layers are notified (TBF establishment failure), transactions in progress are aborted:

– If a TLLI mismatch has occurred during the contention resolution procedure, and the repetition of the packet access has been repeated the maximum number of times as defined in 3GPP TS 04.60, a TBF establishment failure has occurred.

– If the information available in the mobile station, after the reception of an IMMEDIATE ASSIGNMENT message or the second IMMEDIATE ASSIGNMENT message of a two-message assignment, does not satisfactorily define a PDCH, a TBF establishment failure has occurred.

– If the mobile allocation indexes frequencies in more than one frequency band then a TBF establishment failure has occurred.

– If an IMMEDIATE ASSIGNMENT message indicates a PDCH in a non-supported frequency band then a TBF establishment failure has occurred.

On the network side, if timer T3141 elapses before a successful contention resolution procedure is completed, the newly allocated temporary block flow is released as specified in 3GPP TS 04.60 and the packet access is forgotten.

3.5.2.2 Sending an RLC/MAC control message: single block packet access procedure

The sending of an RLC/MAC control message other than the PACKET RESOURCE REQUEST message from a mobile station in packet idle mode to the network may be initiated by the RR entity on the mobile station side using the packet access procedure. If access to the network is allowed (sub-clause 3.5.2.1.1), the packet access is done according to the procedures defined in sub-clauses 3.5.2.1.2 and 3.5.2.1.3, using the single block packet access option defined in sub-clause 3.5.2.1.3.3.

Further action depends on the RLC/MAC control message sent by the mobile station, see 3GPP TS 04.60. Unless otherwise indicated by the RLC/MAC control message, the mobile station remains in packet idle mode.

3.5.3 Packet downlink assignment procedure using CCCH

3.5.3.0 General

The packet downlink assignment procedure using CCCH may be used to establish a temporary block flow to support the transfer of LLC PDUs in the direction from the network to the mobile station.

This procedure may also be used to assign a single downlink block on a PDCH to support the transfer of an RLC/MAC control message from the network to a mobile station in packet idle mode, see sub-clause 3.5.3.2.

3.5.3.1 Entering the packet transfer mode: packet downlink assignment procedure

The establishment of a downlink temporary block flow may be initiated by the RR entity on the network side using the packet downlink assignment procedure. The procedure is triggered by a request from upper layers to transfer a LLC PDU, see 3GPP TS 24.007. The request from upper layers specifies an optional Priority level, a QoS profile including the requested RLC mode, optional DRX parameters, and optional IMSI and an optional MS Radio Access Capability associated with the packet transfer.

Upon such a request, the network shall determine whether the mobile station is in packet idle mode or packet transfer mode. The packet downlink assignment procedure using CCCH is applicable when the mobile station is in packet idle mode and when there is no PCCCH present in the cell.

The network may allocate a temporary flow identity and assign a packet downlink resource comprising one PDCH for a downlink temporary block flow.

3.5.3.1.1 (void)
3.5.3.1.2 Initiation of the packet downlink assignment procedure

The network initiates the packet downlink assignment procedure by sending an IMMEDIATE ASSIGNMENT message in unacknowledged mode on the CCCH timeslot corresponding to CCCH group the mobile station belongs to. appropriate CCCH group is calculated from the IMSI, see 3GPP TS 05.02. The behaviour of the network when the RR entity does not receive the IMSI from the upper layers is implementation dependent for the calculation of the CCCH group where the IMMEDIATE ASSIGNMENT message has to be sent. If the mobile station is in non-DRX mode or if the RR entity does not receive the IMSI or the DRX parameters from the upper layers, there is no further restriction on what part of the downlink CCCH timeslot the IMMEDIATE ASSIGNMENT message, or the first part of the IMMEDIATE ASSIGNMENT message (in the case of a two-message assignment), can be sent. If the mobile station applies DRX, the IMMEDIATE ASSIGNMENT message, or the first part of the IMMEDIATE ASSIGNMENT message (in the case of a two-message assignment), shall be sent in a CCCH block corresponding to a paging group determined for the mobile station in packet idle mode, see 3GPP TS 05.02.

The IMMEDIATE ASSIGNMENT message contains:

– the packet channel description;

– the initial timing advance;

– the packet downlink assignment construction.

The contents of the packet downlink assignment construction determines the further action. At the establishment of a downlink temporary block flow, the packet downlink assignment construction shall contain:

– the TLLI;

– the temporary flow identity;

– the RLC mode;

– the power control parameters;

– the polling bit;

– the initial timing advance validity flag;

– optionally, EGPRS Window Size (see 3GPP TS 04.60) and Link Quality Measurement Mode (see 3GPP TS 04.60);

– optionally, the timing advance index (see 3GPP TS 05.10);

– optionally, the TBF starting time.

If frequency hopping is applied, the network may use the indirect encoding or the direct encoding of the frequency configuration in the Packet Channel Description information element. If the indirect encoding is used, the mobile station uses information received in system information or stored from a previous assignment to determine the frequency parameters, see 3GPP TS 04.60. If the direct encoding is used, the mobile station uses the cell allocation defined for the cell to decode the mobile allocation.

If the indirect encoding is used, the IMMEDIATE ASSIGNMENT message may contain a CHANGE_MARK_1 field. If that is present, the mobile station shall verify the validity of the SI change mark associated with the GPRS mobile allocation to which the message refers, see 3GPP TS 04.60. If the CHANGE_MARK_1 field and the SI change mark do not match, the message does not satisfactorily define a PDCH.

If the mobile station receives an IMMEDIATE ASSIGNMENT message and the Dedicated mode or TBF information element indicates that this is the first message in a two-message assignment, the mobile station shall start listen to the full CCCH. The network may send a second IMMEDIATE ASSIGNMENT message to the mobile station within two multiframe periods following the first IMMEDIATE ASSIGNMENT message, specifying the packet channel description and, if required, a mobile allocation for the assignment. The two IMMEDIATE ASSIGNMENT messages in a two-message assignment shall have the same contents of the Request Reference information elements.

If the mobile station was operating in DRX mode when it received the first message of a two-message assignment, the network shall not send the second IMMEDIATE ASSIGNMENT message within the two block periods immediately following the first message.

If the mobile station does not receive the second IMMEDIATE ASSIGNMENT messages in a two-message assignment within two multiframe periods following the first message, the mobile station shall discard the first IMMEDIATE ASSIGNMENT message received. After the two multiframe periods following the first message, the mobile station may resume to DRX mode.

On receipt of an IMMEDIATE ASSIGNMENT message or, in case of a two-message assignment, a matching pair of IMMEDIATE ASSIGNMENT messages, the mobile station stops monitoring downlink CCCH and switches to the assigned PDCH and starts listening for downlink RLC/MAC blocks identified by the assigned TFI; it starts timer T3190.

The IMMEDIATE ASSIGNMENT message may indicate a TBF starting time. If the mobile station receives the message before the TBF starting time has expired, it shall wait until the frame number indicated by the TBF starting time, start timer T3190 and switch to the assigned PDCH. If the mobile station receives the message after the TBF starting time has expired, it shall ignore the indicated TBF starting time, immediately start timer T3190 and switch to the assigned PDCH.

When the mobile station switches to the assigned PDCH, it shall take the power control parameters received in the IMMEDIATE ASSIGNMENT message into account, perform signal strength measurements and apply output power control procedures as they are defined for packet transfer mode, see 3GPP TS 05.08.

If the Polling bit is set to 1, MS shall send a PACKET CONTROL ACKNOWLEDGEMENT message (see 3GPP TS 04.60) on the assigned PDCH, in the uplink block specified by the TBF Starting Time. In this case the TBF Starting Time is used both to indicate when the assigned PDCH becomes valid and to specify the uplink block. If the TBF Starting Time is not present or has expired, the MS shall ignore the polling request.

An IMMEDIATE ASSIGNMENT message may indicate a timing advance index (TAI) in the packet timing advance IE. The mobile station shall then use the continuous update timing advance mechanism, see 3GPP TS 05.10, using PTCCH in the same timeslot as the assigned PDCH. If there is no indication of a timing advance index, the continuous update timing advance mechanism shall not be used.

The TA_VALID flag indicates if the value of the Timing Advance IE is valid or not.

If the network does not have a valid timing advance value for the mobile station to include in the IMMEDIATE ASSIGNMENT message, the network shall use the procedures defined in 3GPP TS 04.60 on the assigned TBF, or the polling mechanism defined in the above paragraph if the PACKET CONTROL ACKNOWLEDGEMENT format is set to four access bursts, to obtain a timing advance value and to update the initially assigned timing advance value before the mobile station is required to transmit other than access burst on the newly assigned channel.

The packet downlink construction may optionally contain the EGPRS Window Size (see 3GPP TS 04.60) and Link Quality Measurement Mode (see 3GPP TS 04.60). The presence of these fields indicates EGPRS TBF mode (see 3GPP TS 04.60). If these fields are not present, this indicates GPRS TBF mode.

3.5.3.1.3 Packet downlink assignment completion

After having sent the packet downlink assignment, the network starts sending downlink RLC/MAC blocks on the assigned packet downlink resource and the packet downlink assignment procedure is completed at the network side.

On the mobile station side, the procedure is completed when the mobile station receives an RLC/MAC block identified by the assigned temporary flow identity. The mobile station stops timer T3190. The mobile station has entered packet transfer mode.

3.5.3.1.4 Abnormal cases

If a failure occurs on the mobile station side before the packet downlink assignment procedure is completed (TBF establishment failure), the temporary block flow is released; the mobile station returns to packet idle mode:

– If the mobile station does not receive a RLC/MAC block on the assigned PDCHs before timer T3190 expires, then a TBF establishment failure has occurred.

– If the information available in the mobile station, after the reception of an IMMEDIATE ASSIGNMENT message or the second IMMEDIATE ASSIGNMENT message of a two-message assignment, does not satisfactorily define a PDCH, then a TBF establishment failure has occurred.

– If the mobile allocation in the frequency parameters indexes frequencies in more than one frequency band, then a TBF establishment failure has occurred.

If an IMMEDIATE ASSIGNMENT message indicates a PDCH in a non-supported frequency band, then a TBF establishment failure has occurred.

3.5.3.2 Sending an RLC/MAC control message: single block packet downlink assignment procedure

The sending of an RLC/MAC control message to a mobile station in packet idle mode may be initiated by the RR entity on network side using the packet downlink assignment procedure. The procedure is used to assign a single downlink block on a PDCH for the transfer of the RLC/MAC control message. Using this procedure, the network shall not apply segmentation of the RLC/MAC control message.

The single downlink block assignment is done according to the procedure defined in sub-clause 3.5.3.1.2, with the following exceptions:

The packet downlink assignment construction in the IMMEDIATE ASSIGNMENT message shall contain only:

– the TLLI; and

– the TBF starting time.

If the mobile station receives the IMMEDIATE ASSIGNMENT message before the TBF starting time has expired, it shall wait until the frame number indicated by the TBF starting time. The network shall use the TBF starting time to indicate the first frame number belonging to the single block period assigned to the mobile station. The mobile station shall switch to the assigned PDCH and attempt to decode an RLC/MAC control message in the assigned downlink block. Further action depends on the RLC/MAC control message sent by the network, see 3GPP TS 04.60. Unless otherwise indicated by the RLC/MAC control message, the mobile station remains in packet idle mode. If the mobile station remains in packet idle mode, it shall continue to monitor downlink CCCH once the block period indicated by the TBF starting time has passed.

If the mobile station fails to decode or does not receive an RLC/MAC control message in the assigned downlink block, it shall remain in packet idle mode and continue to monitor downlink CCCH once the block period indicated by the TBF starting time has passed.

If the mobile station receives the IMMEDIATE ASSIGNMENT message after the TBF starting time has expired, it shall ignore the assignment.

If a failure occurs on the mobile station side due to any other reason, the mobile station shall ignore the assignment.