3.4.22 RR procedures related to packet resource establishment while in dedicated mode

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

The establishment of a packet resource is supported by procedures on the main DCCH when the mobile station is in dedicated mode. The procedures are only applicable to a mobile station supporting both GPRS and DTM. The procedures are optional for the network.

These procedures constitute a complement to the corresponding procedures for temporary block flow establishment using CCCH or PCCCH while in idle mode defined in 3GPP TS 44.018 and 3GPP TS 44.060, respectively.

The packet request procedure is initiated by the MS and it is described in sub-clause 3.4.22.1. The packet notification procedure is initiated by the network and it is described in sub-clause 3.4.22.2. The packet downlink assignment is initiated by the network and it is described in sub-clause 3.4.22.3.

3.4.22.1 Packet request procedure while in dedicated mode

The packet request procedure using the main DCCH may be used to establish a packet resource to support the transfer of LLC PDUs in the direction from the mobile station to the network.

3.4.22.1.1 Entering the dual transfer mode

While in dedicated mode, the establishment of an uplink packet resource may be initiated by the RR entity of the mobile station using the packet request procedure. The procedure is triggered by a request from upper layers to transfer an LLC PDU; see 3GPP TS 24.007. The request from upper layers specifies:

– TLLI;

– radio priority;

– requested RLC mode associated with the packet transfer;

– LLC frame type;

– establishment cause;

– QoS information for the requested packet session; and

– optionally, the PFI.

Upon such a request, the RR entity of the mobile station:

– if access to the network is allowed (sub-clause 3.4.22.1.1.1), it initiates the packet request procedure as defined in sub-clause 3.4.22.1.1.2;

– otherwise, it rejects the request.

If the request from upper layers indicates any signalling procedure the acknowledged RLC mode shall be requested.

If both the mobile station and the BSS support multiple TBF procedures, or if the mobile station supports RLC non-persistent mode, the BSS may order its preferred RLC mode when establishing uplink packet resources, independently of the RLC mode requested by the mobile station. In particular, if the mobile station supports RLC non-persistent mode the network may allocate an EGPRS TBF that uses this RLC mode.

3.4.22.1.1.1 Permission to access the network

Access to the network is allowed if dual transfer mode is supported in the cell.

NOTE: belonging to an authorised access class or special class, radio priority level and LSA permission are not considered since they only apply to a mobile station in idle mode.

3.4.22.1.1.2 Initiation of establishment of the packet request procedure

The mobile station initiates the establishment of the packet resource by sending a DTM REQUEST message on the main DCCH.

The DTM REQUEST message contains:

– TLLI;

– Channel Request Description;

– Packet establishment cause which indicates, as applicable, a request to send user data, cell update, page response or a mobility management message;

– PFI, if the PFC procedures are supported by the MS and irrespective of the network support of PFC procedures;

– Multiple TBF Capability, irrespective of the network support of Multiple TBF procedures;

– RLC Non-persistent Mode Capability, irrespective of the network support of RLC Non-persistent Mode; and

– MS capabilities related to support of Reduced Latency or FANR, Uplink EGPRS2 and Downlink EGPRS2, irrespective of the network support of these features.

Having sent the DTM REQUEST message, the mobile station starts timer T3148.

3.4.22.1.1.3 Answer from the network

3.4.22.1.1.3.1 Packet assignment

On receipt of a DTM REQUEST message the network may allocate an uplink packet resource. The packet uplink resource is assigned to the mobile station in one of the DTM assignment messages:

– DTM ASSIGNMENT COMMAND; or

– PACKET ASSIGNMENT.

These messages are sent in acknowledged mode. The DTM ASSIGNMENT COMMAND message may be sent on the SDCCH and on the FACCH. The PACKET ASSIGNMENT message shall be sent only on FACCH. If frequency hopping is applied, the mobile station shall use the cell allocation defined for the cell to decode the mobile allocation.

The allocation of the uplink packet resource may imply the reallocation of the resource for the RR connection. In this case, the DTM ASSIGNMENT COMMAND message is used and the timer T3107 is started on the network side. The DTM ASSIGNMENT COMMAND message shall not be used to change to a dependent configuration. The DTM ASSIGNMENT COMMAND message may be used to change the ciphering mode by including the Ciphering Mode Setting IE when a mobile station supports the reception of this IE in the DTM ASSIGNMENT COMMAND message. If Ciphering Mode Setting IE is not present the ciphering mode and the use of Selective Ciphering of Downlink SACCH (see sub-clause 3.4.7a) are unchanged after the mobile station has switched to the assigned channels. If the Ciphering Mode Setting IE indicates "start ciphering" the mobile station supporting Selective Ciphering of Downlink SACCH shall be able to decode both ciphered and not-ciphered SACCH blocks (see sub-clause 3.4.7a). The DTM ASSIGNMENT COMMAND message shall not contain a Cipher Mode Setting IE that indicates "start ciphering" unless a CIPHERING MODE COMMAND message has been transmitted earlier in the RR connection or ciphering has been started earlier in UTRAN. If such a DTM ASSIGNMENT COMMAND message is received it shall be regarded as erroneous, a DTM ASSIGNMENT FAILURE with cause "Protocol error unspecified" message shall be returned immediately, and no further action taken.

When sending the DTM ASSIGNMENT COMMAND message on the network side, and when receiving it on the mobile station side, all transmission of signalling layer messages except for those RR messages needed for this procedure and for abnormal cases is suspended until resumption is indicated. These RR messages can be deduced from sub-clauses 3.4.22.1 and 8.8 Radio Resource management.

The PACKET ASSIGNMENT message is only used when the packet resource is a PDCH and no reallocation of the RR connection is needed.

On receipt of:

– DTM ASSIGNMENT COMMAND message; or

– PACKET ASSIGNMENT message;

the mobile station shall stop T3148.

If the received DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message includes uplink packet resources, the mobile station shall proceed with the packet access. If, in addition, the received DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message includes concurrent downlink packet resources, the mobile station shall also obey the packet downlink assignment. If the received message includes downlink packet resources and no uplink packet resources, the mobile station shall abort the packet access procedure and proceed with the procedure specified in sub-clause 3.4.22.3, and then attempt an establishment of uplink TBF, using the applicable procedure specified in 3GPP TS 44.060.

If the network supports multiple TBF procedures, it shall indicate this support in the Multiple TBF Capability field in the GPRS Cell Options IE included in the DTM Assignment Command and the Packet Assignment messages.

Upon receipt of the DTM ASSIGNMENT COMMAND message, the mobile station initiates a local end release of link layer connections, disconnects the physical channels, commands the switching to the assigned channel and initiates the establishment of lower layer connection (this includes the activation of the channel, their connection and the establishment of the main signalling link).

If the channel mode to be applied corresponds to an initial assignment of a multi-rate speech codec, the DTM ASSIGNMENT COMMAND message shall contain the MultiRate Configuration IE, which defines the set of codec modes and related information to use on the new channel.

If the assignment is related to an assignment from a multi-rate speech codec to a multi-rate speech codec, the MultiRate Configuration IE shall be included in the DTM ASSIGNMENT COMMAND message in the case of full rate to half rate change. If not included in this case, the mobile station shall behave as if the MultiRate Configuration IE was inconsistent. If not included in other cases, the MS shall use on the new channel the AMR configuration it was using on the old channel when it received the DTM ASSIGNMENT COMMAND message.

3.4.22.1.1.3.2 RR reallocation only

If the mobile station receives an ASSIGNMENT COMMAND or HANDOVER COMMAND message during the packet access procedure, the mobile station shall abort the packet access procedure, stop timer T3148 and proceed with the channel assignment procedure as specified in sub-clause 3.4.3 or the handover procedure as specified in sub-clause 3.4.4. The mobile station shall then attempt an establishment of uplink TBF, using the procedure specified in sub-clause 3.4.22.

If the mobile station receives a CHANNEL RELEASE message during the packet access procedure, the mobile station shall abort the packet access procedure, stop timer T3148 and proceed with the RR connection release procedure as specified in sub-clause 3.4.13. The mobile station shall then attempt an establishment of uplink TBF.

If the mobile station receives an INTER SYSTEM TO UTRAN HANDOVER COMMAND message during the packet access procedure, the mobile station shall abort the packet access procedure, stop timer T3148 and proceed with the handover to UTRAN procedure as specified in sub-clause 3.4.4a. If a mobile station which is not UTRAN capable receives this message, the error handling as defined in sub-clause 8.4 applies.

3.4.22.1.1.3.3 Packet request rejection

If the network cannot allocate the requested packet resource it may send the mobile station a DTM REJECT message in acknowledged mode on the main DCCH. This message contains a wait time ("wait indication" information element).

On receipt of the DTM REJECT message, the mobile station stops T3148, notifies upper layers of a packet resource establishment failure and starts timer T3142 with the indicated value.

The mobile station is not allowed to make a new attempt for packet access in the same cell until T3142 expires. The value of the wait indication (i.e. T3142) relates to the cell from which it was received.

3.4.22.1.1.4 Packet request completion

The completion of the packet request procedure depends on the actual assignment message used by the network.

– When the network sends a DTM ASSIGNMENT COMMAND message (i.e. reallocation of the CS resource is required), after the main signalling link is successfully established, the mobile station returns an ASSIGNMENT COMPLETE message, specifying cause "normal event", to the network on the main DCCH. The packet request procedure is completed for the mobile station when the ASSIGNMENT COMPLETE message is sent and for the network when it is received. The network then stops timer T3107. The sending of the ASSIGNMENT COMPLETE message on the mobile station side and its receipt on the network side allow the resumption of the transmission of signalling layer messages other than those belonging to RR management.

– When the network sends a PACKET ASSIGNMENT message, the packet request procedure is completed for the network when assignment message is sent and for the mobile station when it is received.

When the packet request procedure is completed, the mobile station has entered the dual transfer mode.

3.4.22.1.1.5 Abnormal cases

In the following cases, a resource establishment failure has occurred:

a) If a DTM ASSIGNMENT COMMAND message indicates resources in a non-supported frequency band.

b) If the information available in the mobile station after the reception of a DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message does not satisfactorily define uplink packet resources or concurrent uplink and downlink packet resources if both were included in the message.

c) If a DTM ASSIGNMENT COMMAND message includes a mobile allocation or a frequency list that indexes frequencies in more than one frequency band.

d) If a DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message assigns resources not compliant with the multislot capabilities of the mobile station.

e) If the mobile station has no current Cell Allocation (Cell Channel Description) and if it needs a Cell Allocation to analyse the DTM ASSIGNMENT COMMAND message or the PACKET ASSIGNMENT message.

f) If the DTM ASSIGNMENT COMMAND message instructs the mobile station to use a channel description or mode that it does not support.

g) If the DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message does not include any uplink or downlink packet resources.

h) At expiry of timer T3148.

i) If the DTM ASSIGNMENT COMMAND message includes a Channel Mode IE indicating multi-rate speech codec but the Multi-Rate configuration IE is missing and no old multi-rate configuration exists.

j) If the DTM ASSIGNMENT COMMAND message includes a Channel Mode IE indicating multi-rate speech codec and the possibly included Multi-Rate configuration IE is inconsistent.

The MultiRate Configuration IE shall be considered as inconsistent by the mobile station if:

– the active set does not include any codec mode or the active set includes more than four codec modes; or

– one or more codec modes of the active codec set are not supported by the assigned channel; or

– the threshold and hysteresis values are not set according to requirements given in 3GPP TS 45.009.

k) If a PACKET ASSIGNMENT message is received on SDCCH.

l) If the DTM ASSIGNMENT COMMAND message or PACKET ASSIGNMENT message includes the description of a SDCCH channel.

m) If the DTM ASSIGNMENT COMMAND message includes a mode of ciphering not supported by the mobile station.

In any of these cases, the mobile station shall remain in dedicated mode. In addition, if the mobile station has received a DTM ASSIGNMENT COMMAND, it shall return a DTM ASSIGNMENT FAILURE message on the main DCCH with one of the following corresponding cause values:

– In case of abnormal cases a), c) above, "frequency not implemented";

– In case of abnormal cases b), d), g), l), m) above, "protocol error unspecified";

– In case of abnormal case e) above, "no cell allocation available";

– In case of abnormal cases f), i), j) above, "channel mode unacceptable".

Upper layers shall also be notified (resource establishment failure).

In addition:

– If the network commands the mobile station to reallocate the RR connection and the establishment of the main DCCH fails, all the allocated packet resources described in the new configuration are released; the mobile station shall revert to the old channel in dedicated mode, trigger the establishment of the main DCCH and send a DTM ASSIGNMENT FAILURE message on the main DCCH with cause value "lower layer failure".

– If a lower layer failure happens while attempting to connect back to the old channel, the radio link failure procedure is applied (see sub-clause 3.4.13.2).

When receiving the DTM ASSIGNMENT FAILURE message, the network stops T3107.

On the network side, if timer T3107 elapses before either the ASSIGNMENT COMPLETE message has been received on the new channel or a DTM ASSIGNMENT FAILURE message is received on the old channel; the old channel and the new channel are released. On the network side, lower layer failures occurring on the old channel after the sending of the DTM ASSIGNMENT COMMAND message are ignored. Lower layer failures occurring after the receipt of the SABM frame on the new main DCCH are treated following the general rules (cf. sub-clause 3.5.2).

3.4.22.2 Packet notification procedure in dedicated mode

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

3.4.22.2.1 Packet notification initiation by the network

The network initiates the packet notification procedure by sending the mobile station a PACKET NOTIFICATION message on the main DCCH.

The network shall not send the PACKET NOTIFICATION message to a mobile station that does not support dual transfer mode operation. If a mobile station not supporting dual transfer mode receives this message, the error handling as defined in sub-clause 8.4 applies.

3.4.22.2.2 Packet notification response

Upon receipt of the PACKET NOTIFICATION message, the RR sublayer of the mobile station indicates the receipt of a packet paging request to the GMM sublayer; see 3GPP TS 24.007.

3.4.22.3 Packet downlink assignment in dedicated mode

The packet downlink assignment procedure in dedicated mode may be used to establish a packet resource to support the transfer of LLC PDUs in the direction from the network to the mobile station.

This procedure is only applicable to a mobile station in dedicated mode and with no TBF allocated. If the mobile station already has an ongoing TBF, the establishment of the downlink packet resource is performed on the PACCH; see 3GPP TS 44.060.

The establishment of a downlink packet resource is initiated by the RR entity on the network side using the packet downlink assignment procedure in dedicated mode. The procedure is triggered by a request from upper layers to transfer an LLC PDU; see 3GPP TS 24.007. The request from upper layers specifies a QoS profile, an RLC mode, DRX parameters and an MS classmark associated with the packet transfer. The BSS may order its preferred RLC mode independently of the RLC mode signalled from upper layers. If the mobile station supports RLC non-persistent mode the network may allocate an EGPRS TBF that uses this RLC mode.

3.4.22.3.1 Initiation of the packet downlink assignment procedure in dedicated mode

The network initiates the packet downlink assignment procedure in dedicated mode by sending a DTM assignment message (i.e. DTM ASSIGNMENT COMMAND or a PACKET ASSIGNMENT) in acknowledged mode. The DTM ASSIGNMENT COMMAND message may be sent on the SDCCH and on the FACCH. The PACKET ASSIGNMENT message shall be sent only on FACCH.

The allocation of the downlink packet resource may imply the reallocation of the resource for the RR connection. In this case, the DTM ASSIGNMENT COMMAND message is used and the timer T3107 is started on the network side. The DTM ASSIGNMENT COMMAND message shall not be used to change to a dependent configuration. The DTM ASSIGNMENT COMMAND message may be used to change the ciphering mode by including the Ciphering Mode Setting IE when a mobile station supports the reception of this IE in the DTM ASSIGNMENT COMMAND message. The DTM ASSIGNMENT COMMAND message shall not contain a Cipher Mode Setting IE that indicates "start ciphering" unless a CIPHERING MODE COMMAND message has been transmitted earlier in the RR connection or ciphering has been started earlier in UTRAN. If such a DTM ASSIGNMENT COMMAND message is received it shall be regarded as erroneous, a DTM ASSIGNMENT FAILURE with cause "Protocol error unspecified" message shall be returned immediately, and no further action taken.

The network shall not send any of the DTM assignment messages to a mobile station that does not support dual transfer mode operation. If a mobile station not supporting dual transfer mode receives any of these messages, the error handling as defined in sub-clause 8.4 applies.

3.4.22.3.2 Packet downlink assignment completion

The completion of the packet downlink assignment procedure while in dedicated mode depends on the actual assignment message used by the network:

– when the network sends a DTM ASSIGNMENT COMMAND message (i.e. reallocation of the RR connection is required), after the main signalling link is successfully established, the mobile station returns an ASSIGNMENT COMPLETE message, specifying cause "normal event", to the network on the main DCCH. The packet downlink assignment procedure is completed for the mobile station when the ASSIGNMENT COMPLETE message is sent and for the network when it is received. The network then stops timer T3107. The sending of the ASSIGNMENT COMPLETE message on the mobile station side and its receipt on the network side allow the resumption of the transmission of signalling layer messages other than those belonging to RR management.

– when the network sends a PACKET ASSIGNMENT message, the packet downlink assignment procedure is completed for the network when assignment message is sent and for the mobile station when it is received.

3.4.22.3.3 Abnormal cases

In the following cases, a resource establishment failure has occurred:

a) If a DTM ASSIGNMENT COMMAND message indicates packet resources in a non-supported frequency band.

b) If the information available in the mobile station after the reception of a DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message does not satisfactorily define downlink packet resources.

c) If a DTM ASSIGNMENT COMMAND message includes a mobile allocation or a frequency list that indexes frequencies in more than one frequency band.

d) If a DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message assigns resources not compliant with the multislot capabilities of the mobile station.

e) If the mobile station has no current CA and if it needs a CA to analyse the DTM ASSIGNMENT COMMAND message.

f) If the DTM ASSIGNMENT COMMAND message instructs the mobile station to use a channel description or mode that it does not support.

g) If the DTM ASSIGNMENT COMMAND or PACKET ASSIGNMENT message does not include any downlink packet resources, or if it includes uplink packet resources.

h) If the DTM ASSIGNMENT COMMAND message includes a Channel Mode IE indicating multi-rate speech codec but the Multi-Rate configuration IE is missing and no old multi-rate configuration exists.

i) If the DTM ASSIGNMENT COMMAND message includes a Channel Mode IE indicating multi-rate speech codec and the possibly included Multi-Rate configuration IE is inconsistent.

The MultiRate Configuration IE shall be considered as inconsistent by the mobile station if:

– the active set does not include any codec mode or the active set includes more than four codec modes; or

– one or more codec modes of the active codec set are not supported by the assigned channel; or

– the threshold and hysteresis values are not set according to requirements given in 3GPP TS 45.009.

j ) If a PACKET ASSIGNMENT message is received on SDCCH.

k) If the DTM ASSIGNMENT COMMAND message or PACKET ASSIGNMENT message includes the description of a SDCCH channel.

l) If the DTM ASSIGNMENT COMMAND message includes a mode of ciphering not supported by the mobile station.

In any of these cases, the mobile station shall remain in dedicated mode.

If the mobile station has received a DTM ASSIGNMENT COMMAND message, it shall return a DTM ASSIGNMENT FAILURE message on the main DCCH with one of the following corresponding cause values:

– In case of abnormal cases a), c) above, "frequency not implemented";

– In case of abnormal cases b), d), g), k), l) above, "protocol error unspecified";

– In case of abnormal case e) above, "no cell allocation available";

– In case of abnormal case f), h), i) above, "channel mode unacceptable".

In addition:

– If a lower layer failure happens while attempting to connect back to the old channel, the radio link failure procedure is applied (see sub-clause 3.4.13.2).

When receiving the DTM ASSIGNMENT FAILURE message, the network stops T3107.

On the network side, lower layer failures occurring on the old channel after the sending of the DTM ASSIGNMENT COMMAND message are ignored. Lower layer failures occurring after the receipt of the SABM frame on the new main DCCH are treated following the general rules (cf. sub-clause 3.5.2).

3.4.22.4 Modification of packet resources while in DTM

When the mobile station is in dual transfer mode, the network or mobile station may wish to modify only the allocated packet resources. When the mobile station has one or more ongoing TBFs, the procedures described in 3GPP TS 44.060 shall be used.