3.3 RR connection establishment

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

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

3.3.1 RR connection establishment initiated by the mobile station

The purpose of the immediate assignment procedure is to establish an RR connection between the mobile station and the network.

A MS that has enabled PEO or EC operation may optionally support mobile originated RR connection establishment for GSM services (see 3GPP TS 23.060 [74]). If it establishes a RR connection for GSM services then it shall disable GPRS services (see 3GPP TS 23.060 [74]) until the RR connection is released.

3.3.1.1 Entering the dedicated mode : immediate assignment procedure

The immediate assignment procedure can only be initiated by the RR entity of the mobile station. Initiation is triggered by request from the MM sublayer or LLC layer to enter the dedicated mode or by the RR entity in response to a PAGING REQUEST message, to initiate a notification response procedure or to initiate a priority uplink request procedure. Upon such a request:

– if access to the network is allowed (as defined in sub-clause 3.3.1.1.1), the RR entity of the mobile station initiates the immediate assignment procedure as defined in sub-clause 3.3.1.1.2;

– otherwise, it rejects the request.

The request from the MM sublayer to establish an RR connection specifies an establishment cause. Similarly, the request from the RR entity to establish a RR connection in response to a PAGING REQUEST 1, 2 or 3 message specifies one of the establishment causes "answer to paging"; the request from the RR entity to establish an RR connection in order to initiate a notification response procedure or a priority uplink request procedure specifies one of the establishment causes " procedures that can be completed with a SDCCH".

3.3.1.1.1 Permission to access the network

All mobile stations with an inserted SIM are members of one out of 10 access classes numbered 0 to 9. The access class number is stored in the SIM. In addition, mobile stations may be members of one or more out of 5 special access classes (access classes 11 to 15) (see 3GPP TS 22.011), this is also held on the SIM card.

The system information messages on the BCCH broadcast the list of authorized access classes and authorized special access classes, and whether emergency calls are allowed in the cell to all mobile stations or only to the members of authorized special access classes. When network sharing is in use in the cell (see sub-clause 3.8), this information may be broadcast individually for each of the PLMN sharing the cell, and may include different domain-specific access control information for the CS and PS domains.

A mobile station supporting network sharing shall determine whether or not access to the network is allowed using the applicable access control information corresponding to the selected PLMN. In addition, if domain-specific access control is used, a mobile station supporting domain-specific access control shall determine whether or not access to the network is allowed for the domain originating the access attempt, using the access control information corresponding to this domain.

A mobile station configured for EAB and has enabled EAB (i.e. it has received EAB Authorization Mask and EAB Subcategory information for its selected PLMN from SYSTEM INFORMATION TYPE 21) shall, prior to proceeding with a mobile originated access attempt, re-read SI21 if more than 30 seconds have expired since the last time it read SI21.

For a mobile originated access attempt, a mobile station configured for EAB and that has enabled EAB shall perform a preliminary access barring check (see sub-clause 3.3.1.4). If the preliminary access barring check indicates network access is barred then access to the network is not allowed. Otherwise, the mobile station shall proceed according to the remainder of this sub-clause.

If the establishment cause for the request of the MM sublayer is not "emergency call", access to the network is allowed if and only if the mobile station is a member of at least one authorized:

– access class; or

– special access class.

If the establishment cause for the request of the MM sublayer is "emergency call", access to the network is allowed if and only if:

– emergency calls are allowed to all mobile stations in the cell; or

– the mobile station is a member of at least one authorized special access class.

3.3.1.1.1a Implicit reject indication from the network

The network may at any time include an implicit reject indication for the PS domain or the CS domain within an IMMEDIATE ASSIGNMENT message using the IA Rest Octets IE (see sub-clause 10.5.2.16) or within an IMMEDIATE ASSIGNMENT REJECT or an IMMEDIATE ASSIGNMENT EXTENDED or an IMMEDIATE PACKET ASSIGNMENT message using the Feature Indicator IE (see sub-clause 10.5.2.76) or within a PAGING REQUEST TYPE 1 message using the P1 Rest Octets IE (see sub-clause 10.5.2.23) or within a PAGING REQUEST TYPE 2 message using the P2 Rest Octets IE (see sub-clause 10.5.2.24) or within a PAGING REQUEST TYPE 3 message using the P3 Rest Octets IE (see sub-clause 10.5.2.25).

In addition, the network may at any time include an implicit reject indication for the PS domain or the CS domain within an EC IMMEDIATE ASSIGNMENT TYPE 1 message using the Feature Indicator IE (see sub-clause 10.5.2.76).

3.3.1.1.2 Initiation of the immediate assignment procedure

The RR entity of a mobile station, when attempting to establish a CS connection other than for an emergency call or for sending a paging response, and accessing the network when the low priority indicator is set to "MS is configured to NAS signalling low priority" (see 3GPP TS 24.008) shall, while ignoring MS identities included within PAGING REQUEST messages, start listening to the downlink CCCH until successfully decoding one of the RR messages listed in sub-clause 3.3.1.1.1a. If the RR message indicates an implicit reject for the CS domain (see sub-clause 3.3.1.1.1a) the mobile station shall abort the immediate assignment procedure and initiate the Implicit Reject procedure (see sub-clause 3.3.1.1.3.2a).

The RR entity of a mobile station initiates the immediate assignment procedure by scheduling the sending of CHANNEL REQUEST (or EGPRS PACKET CHANNEL REQUEST or EC PACKET CHANNEL REQUEST) messages on the RACH and leaving idle mode (in particular, the mobile station shall ignore PAGING REQUEST messages).

The mobile station then sends maximally M + 1 CHANNEL REQUEST (or EGPRS PACKET CHANNEL REQUEST or EC PACKET CHANNEL REQUEST) messages on the RACH in a way such that:

– when requesting resources for a PS connection other than in the case of sending a paging response, the mobile station shall send the first CHANNEL REQUEST (or EGPRS PACKET CHANNEL REQUEST or EC PACKET CHANNEL REQUEST) message in the first available TDMA frame belonging to the mobile station’s RACH.

– in all other cases, the number of slots belonging to the mobile station’s RACH between initiation of the immediate assignment procedure and the first CHANNEL REQUEST (or EGPRS PACKET CHANNEL REQUEST or EC PACKET CHANNEL REQUEST message) (excluding the slot containing the message itself) is a random value drawn randomly for each new initial assignment initiation with uniform probability distribution in the set {0, 1, …, max (T,8) ‑ 1};

– the number of slots belonging to the mobile station’s RACH between two successive CHANNEL REQUEST (or EGPRS PACKET CHANNEL REQUEST or EC PACKET CHANNEL REQUEST) messages (excluding the slots containing the messages themselves) is a random value drawn randomly for each new transmission with uniform probability distribution in the set
{S, S + 1, …, S + T ‑ 1};

Here, T is the value of the parameter "Tx-integer" broadcast on the BCCH;

M is the value of the parameter "max retrans" broadcast on the BCCH;

S is a parameter depending on the CCCH configuration and on the value of Tx-integer as defined in table 3.3.1.1.2.1.

The CHANNEL REQUEST messages are sent on the RACH (cf. sub-clause 1.5) and contain as parameters:

– an establishment cause which corresponds to the establishment cause given by the MM sublayer and the broadcast NECI value, or which corresponds to one of the establishment causes "answer to paging" given by the RR entity in response to a PAGING REQUEST message including the Channel Needed information, or which corresponds to one of the establishment causes " procedures that can be completed with a SDCCH" given by the RR entity in order to initiate a notification response procedure or a priority uplink request procedure;

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

After sending the first 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.

A mobile station that has initiated the immediate assignment procedure other than for an emergency call or for sending a paging response, and that is accessing the network when the low priority indicator is set to "MS is configured to NAS signalling low priority" (see 3GPP TS 24.008), and has sent one or more CHANNEL REQUEST messages shall proceed as follows:

– If the mobile station receives an IMMEDIATE ASSIGNMENT, an IMMEDIATE ASSIGNMENT EXTENDED or an IMMEDIATE ASSIGNMENT REJECT message corresponding to one of its last 3 transmitted CHANNEL REQUEST messages it shall act on that message as described in sub-clause 3.3.1.1.3.

– If the mobile station succesfully decodes an RR message, which is not a response corresponding to one of its last 3 transmitted CHANNEL REQUEST, that indicates an implicit reject for the CS domain (see sub-clause 3.3.1.1.1a) it shall start timer T3126 (if not already running) and initiate the implicit reject procedure as described in sub-clause 3.3.1.1.3.2a.

Having sent M + 1 CHANNEL REQUEST messages, the RR entity of the mobile station starts timer T3126. At expiry of timer T3126, the immediate assignment procedure is aborted; if the immediate assignment procedure was triggered by a request from the MM sublayer, a random access failure is indicated to the MM sublayer.

Table 3.3.1.1.2.1: Values of parameter S

TX-integer	non combined CCCH	combined CCH/SDCCH
3,8,14,50	55	41
4,9,16	76	52
5,10,20	109	58
6,11,25	163	86
7,12,32	217	115

3.3.1.1.3 Answer from the network

3.3.1.1.3.1 On receipt of a CHANNEL REQUEST message

The network may allocate a dedicated channel to the mobile station by sending an IMMEDIATE ASSIGNMENT message or IMMEDIATE ASSIGNMENT EXTENDED message in unacknowledged mode on the same CCCH timeslot on which it has received the CHANNEL REQUEST. There is no further restriction on what part of the downlink CCCH an IMMEDIATE ASSIGNMENT message or IMMEDIATE ASSIGNMENT EXTENDED message can be sent. The type of channel allocated (SDCCH or TCH; the channel mode shall be set to signalling only) is a network operator decision. Timer T3101 is then started on the network side.

NOTE: There are two types of immediate assignment messages:

– IMMEDIATE ASSIGNMENT message, containing assignment information for one mobile station only;

– IMMEDIATE ASSIGNMENT EXTENDED message, containing assignment information for two mobile stations at the same time.

The IMMEDIATE ASSIGNMENT or IMMEDIATE ASSIGNMENT EXTENDED message contains:

– the description of the assigned channel;

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

– the initial timing advance (cf. 3GPP TS 44.004);

– optionally, a starting time indication.

If frequency hopping is applied, the mobile station uses the last CA received on the BCCH to decode the Mobile Allocation.

On receipt of an IMMEDIATE ASSIGNMENT or IMMEDIATE ASSIGNMENT EXTENDED message corresponding to one of its 3 last CHANNEL REQUEST messages, the mobile station stops T3126 (if running), stops sending CHANNEL REQUEST messages, switches to the assigned channels, sets the channel mode to signalling only and activates the assigned channels. It then establishes the main signalling link with an SABM containing an information field (see sub-clause 3.1.5).

An IMMEDIATE ASSIGNMENT or IMMEDIATE ASSIGNMENT EXTENDED message may indicate a frequency change in progress, with a starting time and possibly alternative channel descriptions.

In the case of the reception of an IMMEDIATE ASSIGNMENT EXTENDED message, or of an IMMEDIATE ASSIGNMENT message which contains only the description of a channel to be used after the starting time, the mobile station shall wait up to the starting time before accessing the channel. If the starting time has already elapsed, the mobile shall access the channel as an immediate reaction to the reception of the message (see 3GPP TS 45.010 for the timing constraints).

If the message contains both the description of a channel to be used after the indicated time and of a channel to be used before, the mobile station accesses a channel as an immediate reaction to the reception of the message. If the moment the mobile station is ready to access is before the indicated time, the mobile station accesses the channels described for before the starting time. The mobile station then changes to the channel described for after the starting time at the indicated time. New parameters can be the mobile allocation and MAIO. Other parameters describing the channel to be used before the starting time are taken from the description of the channel defined for use after the starting time. If the moment the mobile station is ready to access is after the starting time, the mobile station accesses the channel described for after the starting time.

If frequency hopping is applied, the mobile station uses the last CA received on the BCCH.

3.3.1.1.3.2 Assignment rejection

If no channel is available for assignment, 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 T3122 with the indicated value, ("wait indication" information element), starts T3126 if it has not already been started, and listens to the downlink CCCH until T3126 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 3.3.1.1.3.1. If no such immediate assignment is received, the mobile station returns to CCCH idle mode (listening to its paging channel).

As an option the mobile station may return to CCCH idle mode as soon as it has received responses from the network on all, or in case more than 3 were sent the last 3, of its CHANNEL REQUEST messages.

The mobile station is not allowed to make a new attempt to establish a non emergency RR connection in the same cell until T3122 expires. Provided that an IMMEDIATE ASSIGNMENT REJECT message has not been received for an emergency RR connection attempt, the mobile station may attempt to enter the dedicated mode for an emergency call in the same cell before T3122 has expired.

The Wait Indication IE (i.e. T3122) relates to the cell from which it was received.

The mobile station in packet idle mode (only applicable to mobile station supporting GPRS) may initiate packet access in the same cell before T3122 has expired, see 3GPP TS 44.060 and sub-clause 3.5.2.1.3.4.

After T3122 expiry, no CHANNEL REQUEST message shall be sent as a response to a page until a PAGING REQUEST message for the mobile station is received.

3.3.1.1.3.2a Implicit Reject procedure

A mobile station for which timer T3126 or T3146 is running shall proceed as follows:

– While T3126 or T3146 is running, the mobile station listens to the downlink CCCH for a response from the network and is not allowed to make a new access attempt.

– If a response corresponding to any of the last 3 transmitted CHANNEL REQUEST or EGPRS PACKET CHANNEL REQUEST or EC PACKET CHANNEL REQUEST messages is received the mobile station shall stop T3126 or T3146 and act on that message as described in sub-clause 3.3.1.1.3 (if attempting a CS domain access) or as decribed in sub-clause 3.5.2.1.3 (if attempting a PS domain access).

– If T3126 or T3146 expires the mobile station proceeds according to the remainder of this sub-clause.

If the mobile station initiates this procedure due to implicit reject indication received for the CS domain (respectively PS domain) it starts timer T3234 (respectively timer T3236), returns to idle mode and monitors the CCCH. An exception case is where EC operation is enabled in which case the mobile station shall proceed as described in sub-clause 3.5.2a.2 when T3146 expires. The mobile station is not allowed to make a mobile originated access attempt when the low priority indicator is set to "MS is configured to NAS signalling low priority" (see 3GPP TS 24.008) for the CS domain (respectively PS domain) in the same cell until T3234 (respectively T3236) expires or is stopped.

If the mobile station receives a PAGING REQUEST message while T3234/T3236 is running it shall stop T3234/T3236 and respond to the PAGING REQUEST message.

3.3.1.1.4 Assignment completion

The immediate assignment procedure is terminated on the network side when the main signalling link is established. Timer T3101 is stopped and the MM sublayer on the network side is informed that the RR entity has entered the dedicated mode.

On the mobile station side, the procedure is terminated when the establishment of the main signalling link is confirmed. The MM sublayer is informed that the RR entity has entered the dedicated mode.

A DTM capable mobile station in GMM READY state shall perform a Cell Update procedure when it enters dedicated mode from packet idle mode in a cell that supports dual transfer mode. This can be done as early as possible after access but shall be done after sending a CLASSMARK CHANGE message.

3.3.1.1.4.1 Early classmark sending

Early classmark sending consists in the mobile station sending as early as possible after access a CLASSMARK CHANGE message to provide the network with additional classmark information. In addition an MS supporting UTRAN shall send a UTRAN CLASSMARK CHANGE message; an MS supporting CDMA2000 shall send a CDMA2000 CLASSMARK CHANGE message and an MS supporting GERAN Iu mode shall send a GERAN IU MODE CLASSMARK CHANGE message. When a CLASSMARK CHANGE message and one or more additional UTRAN CLASSMARK CHANGE or CDMA2000 CLASSMARK CHANGE or GERAN IU MODE CLASSMARK CHANGE messages are to be sent, the CLASSMARK CHANGE message shall be sent first.

A mobile station which implements the "Controlled Early Classmark Sending" option shall perform the early classmark sending if and only if it is accepted by the network, as indicated in the last reception in the accessed cell of the SYSTEM INFORMATION TYPE 3 message or the PACKET SYSTEM INFORMATION TYPE 2 message (3GPP TS 44.060). If the PACKET SYSTEM INFORMATION TYPE 2 messages have been received, but the Early Classmark Sending Control flag is not included, the mobile station may either read the SYSTEM INFORMATION TYPE 3 message or it shall assume that the early classmark sending is allowed in the cell.

A mobile station which implements support for multiple band shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the support of one or more 3G Radio Access Technology shall also implement the "Controlled Early Classmark Sending" option; in this case neither UTRAN CLASSMARK CHANGE, CDMA2000 CLASSMARK CHANGE nor GERAN IU MODE CLASSMARK CHANGE message shall be sent by the mobile if prohibited by the 3G Early Classmark Sending Restriction parameter in the last reception in the accessed cell of the SYSTEM INFORMATION TYPE 3 message or the PACKET SYSTEM INFORMATION TYPE 2 message (see 3GPP TS 44.060). If the PACKET SYSTEM INFORMATION TYPE 2 messages have been received, but the 3G Early Classmark Sending Restriction flag is not included, the mobile station shall assume neither UTRAN, CDMA2000 nor GERAN IU MODE CLASSMARK CHANGE message shall be sent with the Early Classmark Sending.

A mobile station which implements the "multislot capability" option shall also implement the "Controlled Early Classmark Sending" option.

A mobile station that implements some form of treatment of UCS2 alphabet (see 3GPP TS 23.038) encoded character string (e.g., in short message, or in USSD string) may indicate so in the classmark. (An example is a Mobile Equipment able to display UCS2 encoded character string.) In such a case, it should also implement the "Controlled Early Classmark Sending" option. It is the mobile station responsibility to provide the UCS2 support information in due time. If the network needs this information and the mobile station did not provide it, the network may assume that the Mobile Equipment does not support UCS2.

A mobile station which implements the R-GSM band (see 3GPP TS 45.005) shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the extended measurement function shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the "GPRS" option shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the "SoLSA" option shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the "EDGE" option shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the "LCS" option shall also implement the "Controlled Early Classmark Sending" option.

A mobile station that implements the GERAN Feature Package 2 (see 3GPP TS 24.008) shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the "VAMOS" option shall also implement the "Controlled Early Classmark Sending" option.

A mobile station that implements "Extended TSC sets" option (see 3GPP TS 24.008) shall also implement the "Controlled Early Classmark Sending" option.

A mobile station which implements the "Controlled Early Classmark Sending" option shall indicate it in the classmark (ES IND bit).

3.3.1.1.4.2 Service information sending

Service information sending consists in a mobile station in class A mode of operation sending a SERVICE INFORMATION message and in a mobile station in class B mode of operation sending a GPRS SUSPENSION REQUEST message, providing additional service information to the network.

A mobile station in class A mode of operation which supports the MBMS feature and requires notification of commencing MBMS sessions during dedicated mode operation, shall perform the service information sending procedure:

– at the earliest opportunity after the early Classmark sending procedure and any DTM related signalling, if and only if the dedicated mode MBMS notification feature is supported in the cell as indicated in the GPRS Cell Options (see 3GPP TS 44.060) or DTM INFORMATION message or System Information Type 6 message; or

– if the P-TMSI of the MS is reallocated during the CS connection and the dedicated mode MBMS notification feature is supported in the cell as indicated in the GPRS Cell Options (see 3GPP TS 44.060) or DTM INFORMATION message or System Information Type 6 message; or

– on the main DCCH of a target cell after successfully completing the handover procedure, if indicated to do so in the HANDOVER COMMAND message (see sub-clause 3.4.4.1) and the dedicated mode MBMS notification feature is supported in the target cell as indicated in the GPRS Cell Options (see 3GPP TS 44.060) or DTM INFORMATION message or System Information Type 6 message.

3.3.1.1.5 Abnormal cases

If a lower layer failure occurs on the mobile station side on the new channel before the successful establishment of the main signalling link, the allocated channels are released; the subsequent behaviour of the mobile station depends on the type of failure and previous actions.

– If the failure is due to information field mismatch in the contention resolution procedure, see sub-clause 3.1.5, and no repetition as described in this paragraph has been performed, the immediate assignment procedure shall be repeated.

– If the failure is due to any other reason or if a repetition triggered by a contention resolution failure has been performed. The mobile station returns to idle mode (RR connection establishment failure), transactions in progress are aborted and cell reselection then may take place.

If the information available in the mobile station, after the reception of an IMMEDIATE ASSIGNMENT message does not satisfactorily define a channel, an RR connection establishment failure has occurred.

If the Mobile Allocation IE indexes frequencies in more than one frequency band then a RR connection establishment failure has occurred.

If an IMMEDIATE ASSIGNMENT message indicates (a) channel(s) in a different frequency band to which the CHANNEL REQUEST message was sent then, if the frequency band is supported by the mobile station, the mobile station shall access the indicated channel(s) with the same power control level as used for the CHANNEL REQUEST message.

If an IMMEDIATE ASSIGNMENT message indicates a channel in non-supported frequency band then a RR connection establishment failure has occurred.

On the network side, if timer T3101 elapses before the main signalling link is established, the newly allocated channels are released and the request is forgotten. Note that the network has no means to distinguish repeated attempts from initial attempts from a mobile station.

3.3.1.2 Entering the group transmit mode: uplink access procedure

Only applicable for mobile stations supporting "VGCS transmit".

The purpose of the uplink control procedure is to establish an RR connection on a VGCS channel between a mobile station which is in group receive mode on that channel and the network.

The mobile station enters the group transmit mode when a successful establishment of the RR connection is indicated. The channel mode assumed by the mobile station is the one derived from the channel description.

When the network supports talker priority or sending application-specific data, it shall provide on the NCH in combination with the UPLINK_BUSY message on the group call channel downlink, the method that the MS shall use to issue priority talker requests.

NOTE: The only indication of support of talker priority by the network is the presence of the Talker Priority and Emergency Indication IE in the UPLINK BUSY message (see sub-clause 9.1.46.1).

3.3.1.2.1 Mobile station side

3.3.1.2.1.1 Uplink investigation procedure – talker priority not supported by the network

The mobile station in group receive mode shall consider the uplink as free if the last message indicating the uplink as being free was received less than 480 ms ago and if no UPLINK BUSY message has been received since the last message indicating the uplink as free.

On receipt of a request from the upper layer to access the uplink and if the uplink is not free, the mobile station starts the timer T3128.

If the uplink is free or becomes free before expiry of timer T3128, then the uplink investigation procedure is terminated, the mobile station shall stop T3128, and start the uplink access procedure.

NOTE: The start of the uplink access procedure is not subject to the access class of the mobile station.

If the uplink is not indicated free before the timer expires, the mobile station shall remain in the group receive mode and indicate a reject of the uplink request to the upper layer.

3.3.1.2.1.1a Uplink investigation procedure – talker priority supported by the network

On receipt of a privilege, emergency priority or emergency reset request from the upper layer to access the uplink, the mobile station shall verify that the requested priority is permitted according to the SIM/USIM. If the mobile station is not permitted to use the requested talker priority then it shall indicate a rejection of the uplink request to the upper layers.

On receipt of a request from the upper layer to access the uplink and if the uplink is busy with a priority equal or higher than the requested priority, the mobile station starts the timer T3128.

If the uplink is free, becomes free before expiry of timer T3128 or the current talker priority is less than the priority of the request from the upper layer, then the uplink investigation procedure is terminated, the mobile station shall stop T3128 if running, and start the uplink access. If the uplink is busy, the MS shall determine whether to start the uplink access or priority uplink request procedure based on the priority uplink access parameter broadcast on the NCH and the uplink access indication in the latest UPLINK BUSY message received in the cell.

If the priority uplink access parameter broadcast on the NCH indicates "RACH access" but the latest UPLINK BUSY message received in the cell indicates that the voice group call channel is available for uplink access requests, the MS shall start an uplink access procedure; otherwise the MS starts the priority uplink request procedure.

If the priority uplink access parameter broadcast on the NCH indicates "Group Channel" then the MS always shall start an uplink access procedure.

NOTE: The start of the uplink access procedure is not subject to the access class of the mobile station.

If the mobile station is unable to start the uplink access or priority uplink request procedure before timer T3128 expires, the mobile station shall remain in the group receive mode and indicate a reject of the uplink request to the upper layer.

3.3.1.2.1.2 Uplink access procedure with talker priority not supported by the network

The mobile station shall send UPLINK ACCESS messages on the voice group call channel with the appropriate establishment cause. These messages shall be sent unciphered. The first UPLINK ACCESS message shall be transmitted by the mobile station with a random delay between 0 and 20 ms.

Having sent the first UPLINK ACCESS message, the mobile station starts timer T3130. The mobile station shall send the UPLINK ACCESS message repeatedly with an interval of 100ms plus a random delay between 0 and 20 ms up to five times. At expiry of timer T3130, the mobile station shall repeat the same procedure if the uplink is free. Timer T3130 may 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 UPLINK ACCESS messages contain a random reference which is drawn randomly from a uniform probability distribution. The UPLINK ACCESS messages repetitions shall contain the same random reference as the one contained in the first message.

If an uplink identity code (UIC) of the current cell has been provided by the network in the UPLINK FREE message, the mobile station shall use this UIC IE for the coding of the UPLINK ACCESS messages (see 3GPP TS 45.003). If no UIC is provided, the mobile station shall use the BSIC received from the current cell, for instance from the initial synchronization.

If no VGCS UPLINK GRANT or UPLINK BUSY message is received by the mobile station 480 ms after having sent the first UPLINK ACCESS message, the mobile station shall stop sending UPLINK ACCESS messages and wait in order to receive a VGCS UPLINK GRANT or UPLINK BUSY message.

On receipt of a VGCS UPLINK GRANT message corresponding to one of its UPLINK ACCESS messages, the mobile station stops T3130, stops sending UPLINK ACCESS messages, and establishes the main signalling link with an SABM containing the TALKER INDICATION message in the information field. The ciphering key sequence number shall be included in the TALKER INDICATION message if the group call is ciphered. Early classmark sending shall be performed if applicable. If a UA is received containing the message sent, the mobile station enters the group transmit mode and indicates the successful seizure of the uplink to the upper layer. If a UA is received with a message different from the message sent, the mobile station shall remain in the group receive mode and indicate the rejection of the uplink request to the upper layers.

On receipt of a VGCS_UPLINK_GRANT message aimed to another mobile station (i.e. not corresponding to one of its UPLINK ACCESS messages sent for this uplink request), the mobile station shall stop timer T3130 and shall not send UPLINK ACCESS message and shall start timer T3224. If the mobile station receive an UPLINK BUSY message before timer T3224 expires, it shall stop timer T3224 and remain in the group receive mode and shall indicate a rejection of the uplink request to the upper layers. Otherwise it shall follow the same procedures as for expiry of timer T3130.

When receiving an UPLINK BUSY message, the mobile station stops T3130 and stops sending UPLINK ACCESS messages. The mobile shall remain in the group receive mode and shall indicate a rejection of the uplink request to the upper layers.

3.3.1.2.1.2a Uplink access procedure – with talker priority supported by the network using uplink access procedure

3.3.1.2.1.2a.1 Talker priority normal, privileged or emergency

Having sent the first UPLINK ACCESS message, the mobile station starts timer T3130. The mobile station shall send the UPLINK ACCESS message repeatedly up to five times. The interval between two sequential messages shall be 100ms plus a random delay between 0 and 20ms if the priority of the current uplink access is normal, or 80ms plus a random delay between 0 and 20ms if the priority of the current uplink access is privileged or emergency. At expiry of timer T3130, the mobile station shall repeat the same procedure if the uplink is free or the current talker priority is less than that of this uplink request. Timer T3130 may 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.

If no VGCS UPLINK GRANT or UPLINK BUSY message is received by the mobile station 480 ms after having sent the first UPLINK ACCESS message for this uplink request, the mobile station shall stop sending UPLINK ACCESS messages and wait in order to receive a VGCS UPLINK GRANT or UPLINK BUSY message.

On receipt of a VGCS_UPLINK_GRANT message aimed to another mobile station (i.e. not corresponding to one of its UPLINK ACCESS messages sent for this uplink request), the mobile station shall stop timer T3130 and shall not send UPLINK ACCESS message and shall start timer T3224. If an UPLINK BUSY message is received before timer T3224 expires, the mobile station shall stop the timer. If the UPLINK BUSY message indicates a priority lower than the priority of the current uplink access, the mobile station shall resend the UPLINK_ACCESS message, otherwise, it shall remain in the group receive mode and shall indicate a rejection of the uplink request to the upper layers. If timer T3224 expires, the mobile station shall follow the same procedures as for expiry of timer T3130.

When receiving an UPLINK BUSY message indicating a priority that is equal or higher than the priority of the current uplink access, the mobile station stops T3130 and stops sending UPLINK ACCESS messages for this uplink request. The mobile shall remain in the group receive mode and shall indicate a rejection of the uplink request to the upper layers.

When receiving an UPLINK BUSY message indicating that the voice group call channel is not available for uplink access requests the mobile station stops T3130, stops sending UPLINK ACCESS messages and initiates the priority uplink request procedure.

When receiving an UPLINK RELEASE message during RR connection establishment on the group channel, the mobile station shall remain in the group receive mode and shall indicate a rejection of the uplink request to the upper layers.

3.3.1.2.1.2a.2 Emergency mode reset request

When receiving an UPLINK BUSY message indicating that the voice group call channel is not available for uplink access requests the mobile station stops T3130, stops sending UPLINK ACCESS messages for this uplink request and initiates the priority uplink request procedure.

On receipt of an VGCS UPLINK GRANT message corresponding to one of its UPLINK ACCESS messages for the current uplink access, the mobile station stops T3130, stops sending additional UPLINK ACCESS messages for this UPLINK REQUEST, and establishes the main signalling link with an SABM/UA exchange containing the TALKER INDICATION message in the information field, as described in 3.3.1.2.1.2.2.

When receiving an UPLINK BUSY or UPLINK FREE message indicating that the emergency mode is not set or a VGCS UPLINK GRANT message aimed to another mobile station (i.e. not corresponding to one of its UPLINK ACCESS messages sent for this uplink request), the mobile station stops T3130 and stops sending additional UPLINK ACCESS messages for this uplink request. The mobile shall remain in the group receive mode and shall indicate a rejection of the uplink request to the upper layers if the emergency mode is still set.

3.3.1.2.1.2b Priority uplink request procedure

3.3.1.2.1.2b.1 Talker priority privileged or emergency

The mobile station shall temporarily leave group receive mode and initiate the immediate assignment procedure, as specified in 3.3.1.1. The mobile station shall store for comparison purposes the frame number of the frame in which the CHANNEL REQUEST message was sent to initiate the Priority Uplink access. The establishment of a signalling link is then initiated by use of a SABM, with information field containing the PRIORITY UPLINK REQUEST message (see subclause 3.1.5). The mobile identity, reduced group call reference, random reference and the type of request shall be included in the PRIORITY UPLINK REQUEST message. Once a UA is received from the network, containing the message sent, the mobile station waits for the signalling link to be released. On receipt of a CHANNEL RELEASE message (with the group channel description) the mobile station sends a DISCONNECT message to the network, returns to group receive mode, and starts T3130.

On receipt of a VGCS UPLINK GRANT message with request reference corresponding to the random reference and frame number stored in the MS, the mobile station stops T3130, and establishes the main signalling link with a SABM/ UA exchange containing the TALKER INDICATION message in the information field. The ciphering key sequence number shall be included in the TALKER INDICATION message. Early classmark sending shall be performed if applicable. If a UA is received containing the message sent, the mobile station enters the group transmit mode and indicates the successful seizure of the uplink to the upper layer. If a UA is received with a message different from the message sent, the mobile station shall remain in the group receive mode and indicate the rejection of the uplink request to the upper layers.

On receipt of a VGCS_UPLINK_GRANT message aimed to another mobile station (i.e. not corresponding to the random reference and frame number stored in the MS), the mobile station shall stop timer T3130 and start timer T3224. If an UPLINK BUSY message is received before timer T3224 expires, the mobile station shall stop the timer. If the UPLINK BUSY message indicates a priority lower than the priority of the current priority uplink request, the mobile station shall resend the PRIORITY UPLINK REQUEST message, otherwise, it shall remain in the group receive mode and shall indicate a rejection of the priority uplink request to the upper layers. If timer T3224 expires, the mobile station shall follow the same procedures as for expiry of timer T3130.

When receiving an UPLINK BUSY message indicating a priority that is equal or higher than the priority of the current priority uplink request, the mobile station stops T3130. The mobile shall remain in the group receive mode and shall indicate a rejection of the priority uplink request to the upper layers.

At expiry of timer T3130, the mobile station shall repeat the same procedure if the current talker priority is less than that of the requested priority, use the uplink access procedure if the uplink is free or use the uplink access procedure if the latest UPLINK BUSY message received in the cell indicates that the voice group call channel is available for uplink access requests. A maximum of three attempts is allowed and after that a rejection of the priority uplink request is indicated to the upper layers.

3.3.1.2.1.2b.2 Emergency mode reset request

The mobile station shall temporarily leave the group receive mode and initiate the immediate assignment procedure, as specified in 3.3.1.1. The establishment of a signalling link is then initiated by use of a SABM, with information field containing the PRIORITY UPLINK REQUEST message with cause Reset Emergency Talker Indication (see subclause 3.1.5). The mobile identity, reduced group call reference, and random reference shall be included in the PRIORITY UPLINK message. Once a UA is received from the network, containing the message sent, the mobile station waits for the signalling link to be released. On receipt of a CHANNEL RELEASE message (with the group channel description) the mobile station sends a DISCONNECT to the network and returns to group receive mode.

3.3.1.2.1.2b.3 Validation of priority uplink requests for ciphered voice group calls

When validation of priority uplink requests is required by the operator, the MS shall store the token received from the network in UPLINK BUSY and periodic UPLINK BUSY messages on the main signalling link. When a listener sends a PRIORITY UPLINK REQUEST message, the MS shall include the token as a parameter and follow the procedures specified in 3.3.1.2.1.2b.1 and 3.3.1.2.1.2b.2.

The MS shall always use the latest available token.

If an UPLINK BUSY message is received with a new token and a priority that is less than that of a MSs outstanding priority uplink request, the mobile station shall stop T3130, temporarily leave the group receive mode in order to resend the PRIORITY UPLINK REQUEST with the new token and return to the group receive mode to wait for the VGCS UPLINK GRANT message.

If at expiry of T3130 the uplink is still busy and the mobile station repeats the priority uplink request procedure, the MS shall use a different token, if available.

3.3.1.2.1.2c Uplink access procedure for sending application-specific data

3.3.1.2.1.2c.1 General

The transmission of application-specific data by the mobile station in group receive mode to the network is carried out by the mobile temporarily leaving group receive mode, establishing a L2 connection and sending a L3 message containing the application-specific data in the SABM frame used to establish the main signalling link on a dedicated channel. The dedicated channel may be either the group call channel or another channel assigned by the network.

3.3.1.2.1.2c.2 Using the Voice Group Call Channel

If an UPLINK FREE message has been received and no subsequent UPLINK BUSY message has been received, or the last UPLINK BUSY message received in the cell indicates that the group channel shall be used to send application-specific data, the mobile station shall send UPLINK ACCESS messages on the voice group call channel with the establishment cause "UL request for sending application-specific data" to request a L2 connection. The mobile station shall then wait for a VGCS UPLINK GRANT message. When the VGCS UPLINK GRANT message is received by the mobile station, it establishes the main signalling link by sending a SABM command containing a DATA INDICATION message in the information field (see sub-clause 3.1.5).

Once contention resolution is complete, no further data shall be transmitted by the mobile station on the dedicated channel.. On receipt of an UPLINK RELEASE message, the MS returns to group receive mode.

3.3.1.2.1.2c.3 Using the RACH

If the most recent UPLINK BUSY message received in the cell indicates that RACH Access shall be used (and no UPLINK FREE message has been received more recently), the mobile station shall temporarily leave group receive mode and send a CHANNEL REQUEST message on the RACH with the appropriate establishment cause (see sub-clause 9.1.8). On receipt of an IMMEDIATE ASSIGNMENT, the main signalling link is then established as specified in 3.1.5 by use of a SABM with information field containing the DATA INDICATION 2 message.

Once contention resolution is complete, no further data shall be transmitted by the mobile station on the dedicated channel. On receipt of an CHANNEL RELEASE message, the mobile station returns to group receive mode.

3.3.1.2.2 Network side – talker priority not supported by the network

On receipt of an UPLINK ACCESS message the network shall perform, if necessary, contention resolution and grant the uplink to one mobile station by sending a VGCS UPLINK GRANT message to the mobile station in unacknowledged mode on the main signalling link. Furthermore, the network shall provide UPLINK BUSY messages on the main signalling link in all cells of the group call area. After having sent the first message, the network starts T3115. If the timer expires before the reception of a correctly decoded frame from the MS, the network repeats the VGCS UPLINK GRANT message to the mobile station, reset and restarts timer T3115. If the VGCS UPLINK GRANT message has been repeated Ny2 times without a correctly decoded frame being received from the MS, the network shall stop sending VGCS UPLINK GRANT messages and provide an UPLINK FREE message on the main signalling channel and wait for a new UPLINK ACCESS message. The correct decoding of a frame means that the decoding algorithm and the error detection tests, if any, indicate no error.

After the data link layer is established, the RR entity of the network shall analyse the TALKER INDICATION message received from the mobile station, adapt the RR procedures to the new classmark if necessary and provide the mobile subscriber identity and ciphering key sequence number to the upper layer.

3.3.1.2.2a Network side – network supports talker priority using uplink access procedure

3.3.1.2.2a.1 Uplink FREE

3.3.1.2.2a.1.1 Uplink Access cause – Normal, Privileged, or Emergency priority request

As per sub-clause 3.3.1.2.2, with the following exceptions:

– The UPLINK BUSY message shall contain the priority of the uplink request;

– The UPLINK BUSY message shall be transmitted every T3151 seconds;

– In the case of an uplink request with priority set to emergency that is accepted by the network (see 3GPP TS 48.008), the emergency indication shall be set in all UPLINK BUSY messages.

– The UPLINK BUSY message shall contain the Uplink Access Indication IE to inform the mobile station of the channel to be used in the cell for priority uplink access. If "RACH Access" is indicated on the NCH and the group call channel uplink in the cell is not used, the network shall indicate "Group Channel" in the UPLINK BUSY message; otherwise, the network shall indicate "RACH Access" in the UPLINK BUSY message.

3.3.1.2.2a.1.2 Uplink Access cause – Emergency mode reset request

On receipt of an UPLINK ACCESS message with cause Emergency mode reset request when the emergency mode is set, the network shall perform, if necessary, contention resolution and grant the uplink to one mobile station by sending a VGCS UPLINK GRANT message to the mobile station in unacknowledged mode on the main signalling link. After having sent the first message, the network starts T3115. If the timer expires before the reception of a correctly decoded frame from the MS, the network repeats the VGCS UPLINK GRANT message to the mobile station, reset and restarts timer T3115. If the VGCS UPLINK GRANT message has been repeated Ny2 times without a correctly decoded frame being received from the MS, the network shall stop sending VGCS UPLINK GRANT messages and wait for a new UPLINK ACCESS message. The correct decoding of a frame means that the decoding algorithm and the error detection tests, if any, indicate no error.

After the data link layer is established, the RR entity of the network shall analyse the TALKER INDICATION message received from the mobile station. The mobile subscriber identity is provided to the upper layer. The network shall then send an UPLINK RELEASE message to the mobile station.

If emergency mode is not set within the network then the network discards the Emergency mode reset request.

3.3.1.2.2a.2 Uplink BUSY

3.3.1.2.2a.2.1 Uplink Access with cause priority less than or equal to current talker priority

The Uplink Access request shall be discarded.

3.3.1.2.2a.2.2 Uplink Access with cause priority higher than current talker priority

On receipt of an UPLINK ACCESS message the network shall perform, if necessary, contention resolution and grant the uplink of the voice group channel to one mobile station by sending a VGCS UPLINK GRANT message to the mobile station in unacknowledged mode on the main signalling link.

After having sent the first message, the network starts T3115. If the timer expires before the reception of a correctly decoded frame from the MS, the network repeats the VGCS UPLINK GRANT message to the mobile station, reset and restarts timer T3115. If the VGCS UPLINK GRANT message has been repeated Ny2 times without a correctly decoded frame being received from the MS, the network shall stop sending VGCS UPLINK GRANT messages. The correct decoding of a frame means that the decoding algorithm and the error detection tests, if any, indicate no error.

The network shall provide UPLINK BUSY messages on the main signalling link in all cells of the group call area, containing the latest validated priority. The UPLINK BUSY message shall be transmitted every T3151 seconds.

3.3.1.2.2a.2.3 Uplink Access with cause Emergency mode reset request

As per sub-clause 3.3.1.2.2a.1.2, with the following exception:

– If the emergency mode reset request is accepted by the network (see 3GPP TS 48.008), the network shall provide UPLINK BUSY messages, with the emergency mode not set and the priority set to normal, on the main signalling link in all of the cells of the group call area. These UPLINK BUSY messages shall be transmitted every T3151 seconds.

3.3.1.2.2b Network side – network supports talker priority using priority uplink procedure

3.3.1.2.2b.1 Uplink FREE

3.3.1.2.2b.1.1 Uplink Access cause – Normal, Privileged, or Emergency priority request

As per sub-clause 3.3.1.2.2, with the exception that the UPLINK BUSY messages are transmitted every T3151 seconds.

3.3.1.2.2b.1.2 Uplink Access cause – Emergency mode reset request

As per subclause 3.3.1.2.2a.1.2.

3.3.1.2.2b.2 Uplink BUSY

3.3.1.2.2b.2.1 Priority Uplink Request with cause priority less than or equal to current talker priority

The Priority Uplink Request shall be discarded.

3.3.1.2.2b.2.2 Priority Uplink Request with cause priority higher than current talker priority

On receipt of a priority uplink request message the network stops timer T3101 and releases the dedicated signalling link established by the MS. The RR entity of the network shall analyse the message and provide the message parameters to the upper layer. The network shall perform contention resolution, if necessary. The network shall release the current talker and grant the uplink to one mobile station by sending a VGCS UPLINK GRANT message to the mobile station in unacknowledged mode on the main signalling link. The VGCS UPLINK GRANT shall contain the request reference parameter with the random reference set to the value received in the PRIORITY UPLINK REQUEST and the frame number of the frame in which the CHANNEL REQUEST message was sent to establish the dedicated signalling link.

3.3.1.2.2b.2.3 Priority Uplink Request with cause Emergency mode reset request

On receipt of a PRIORITY UPLINK REQUEST message with cause Reset Emergency Talker Indication the network stops timer T3101 and releases the dedicated signalling link established by the MS. The RR entity of the network shall analyse the message and provide the message parameters to the upper layer. The network shall perform contention resolution, if necessary, and reset the Emergency Indication of the group call. The current talker is not released.

3.3.1.2.2b.2.4 Validation of Priority Uplink Requests for ciphered voice group calls

When validation of priority uplink requests is required by the operator, the network shall broadcast a randomly generated 32bit token in an UPLINK BUSY message each time the uplink becomes busy after being free. The 32bit token is randomly generated on a per BSS basis. A new token shall subsequently be broadcast each time a periodic UPLINK BUSY message is sent (i.e. every T3151 seconds). If, on T3151 expiry, the old token has not been used it remains valid for a further T3157 seconds along with the new token. Once T3157 expires only the new token is valid.

On receipt of a priority uplink request message the network stops timer T3101 and releases the dedicated signalling link established by the MS. The RR entity of the network shall analyse the message and if a token is received in the message and it matches that stored in the network, the network shall provide the message parameters to the upper layer and continue handling the request as defined in 3.3.1.2.2b.2.2 and 3.3.1.2.2b.2.3. In addition, a new token and the priority of the accepted request is broadcast in an UPLINK BUSY message on the main signalling link after T3155 seconds and T3151 is reset and restarted. If a token is not received in the message, or the token received does not match that stored in the network, the network shall ignore the request.

The dedicated signalling link established by the MS is always acknowledged and released by sending UA (Priority Uplink Request) followed by Channel Release, whether or not the network accepts or ignores the request.

3.3.1.2.2c Network side – network supports sending application-specific data by mobile station

3.3.1.2.2c.1 General

The network shall send UPLINK BUSY messages every T3151 seconds in all cells in the group call area while the uplink for this group call is busy in any cell.

The mobile station behaviour is described in sub-clause 3.3.1.2.1.2c.

3.3.1.2.2c.2 Using the Voice Group Call Channel

On receipt of an UPLINK ACCESS message on the voice group call channel indicating a cause "UL request for sending application-specific data" the network shall grant the uplink of the voice group channel by sending a VGCS UPLINK GRANT message to the mobile station in unacknowledged mode on the main signalling link. After the data link layer is established (see sub-clauses 3.3.1.2.1.2c.2 and 3.1.5) the BSS releases the uplink channel by sending an UPLINK RELEASE message.

3.3.1.2.2c.3 Using the RACH

On receipt of a CHANNEL REQUEST message with the appropriate establishment cause for sending application-specific data (see sub-clause 9.1.8), the BSS shall allocate a channel to the mobile station by sending an IMMEDIATE ASSIGNMENT message. As soon as contention resolution is completed (see sub-clause 3.1.5 and 3.3.1.2.1.2c.3) and the data link layer is established, the BSS sends an CHANNEL RELEASE message to the mobile.

3.3.1.2.3 Abnormal cases

If a lower link failure has occurred or an indication of the release of the data link layer was provided by the lower layer and no RR release request was previously received from the upper layer, the network shall provide an UPLINK FREE message on the main signalling channel and wait for a new UPLINK ACCESS message.

The network shall discard an UPLINK ACCESS message or PRIORITY UPLINK REQUEST message that contains an unknown cause field.

3.3.1.3 Dedicated mode and GPRS

A mobile station whose Channel Request message contained a packet access establishment cause may receive an Immediate Assignment message to a Channel which is to be used in dedicated mode. A mobile station supporting the "GPRS" option shall not obey this command.

3.3.1.4 Preliminary Access Barring Check

The preliminary access barring check shall indicate network access is barred if all of the following conditions are satisfied:

– the establishment cause for the request received from the MM sublayer is not "emergency call".

– the SYSTEM INFORMATION TYPE 21 message is broadcast in the cell and includes EAB information;

– the mobile station is a member of a subcategory of mobile stations targeted by the EAB information;

– the EAB Authorization Mask sent in the EAB information indicates the mobile station’s access class is not authorized;

– the mobile station is not a member of any of the authorized special access classes (i.e. an Access Class in the range 11-15) permitted by the network;

Otherwise, the preliminary access barring check shall indicate network access is not barred.

When network sharing is in use in the cell, a mobile station supporting network sharing shall check the above conditions using the broadcast information corresponding to the selected PLMN.

3.3.2 Paging procedure for RR connection establishment

The network can initiate the establishment of an RR connection by the paging procedure for RR connection establishment. Such a procedure can only be initiated by the network.

3.3.2.1 Paging initiation by the network

The network initiates the paging procedure to trigger RR connection establishment by broadcasting a paging request message on the appropriate paging subchannel on CCCH or PCCCH, and starts timer T3113. The paging subchannels on CCCH and PCCCH are specified in 3GPP TS 45.002 and 3GPP TS 43.013.

The network may also send paging related information on PACCH to a mobile station in packet transfer mode, see sub-clause 3.3.2.1.3.

The network may also broadcast paging related information on any voice broadcast or voice group call channel downlink. The network shall indicate in the Notification/FACCH message sent on the voice broadcast or voice group call channel whether the paging is for a mobile terminating call, USSD or short message, if such information was provided to the BSS by the MSC in the Paging Information IE (see 3GPP TS 48.008).

3.3.2.1.1 Paging initiation using paging subchannel on CCCH

Paging initiation using the paging subchannel on CCCH is used when sending paging information to a mobile station in idle mode. It is also used when sending paging information to a mobile station in packet idle mode, if PCCCH is not present in the cell.

NOTE 1: There are 3 types of paging messages which may be used on CCCH:

– PAGING REQUEST TYPE 1;

– PAGING REQUEST TYPE 2; and

– PAGING REQUEST TYPE 3.

In a PAGING REQUEST message on CCCH to trigger RR connection establishment, the mobile station shall be identified by the TMSI (non-GPRS TMSI) or its IMSI. If the mobile station is identified by the TMSI, it shall proceed as specified in sub-clause 3.3.2.2.

If the mobile station in packet idle mode is 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 on CCCH includes for each mobile station that is paged to trigger RR connection establishment an indication which defines how mobiles of different capabilities shall code the establishment cause field in the CHANNEL REQUEST message. The information received in the CHANNEL REQUEST can be used by the network to assign a suitable channel.

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

A PAGING REQUEST TYPE 1 message on CCCH may have additionally a notification message coded in the P1 rest octets information element. The notification for one group call may be segmented over two PCH blocks. When the notification is segmented over two PCH blocks the second segment shall be sent at the next but one PCH block after the PCH block containing the first segment. The mobile station may receive the second segment before the first segment.

A PAGING REQUEST message on CCCH may also include priority levels related to the mobile station identifications. A mobile station in group receive mode supporting eMLPP shall take into account this information to decide whether to respond to this PAGING REQUEST and, if the call is answered, the mobile station shall store the priority level for the duration of the call. A mobile station not supporting eMLPP shall ignore this information element when received in a PAGING REQUEST message.

NOTE 2: A mobile station not supporting VGCS or VBS may ignore this information element when received in a PAGING REQUEST message, since the priority level is also provided in the SETUP message.

If VGCS or VBS is supported by the network, messages sent on the PCH may also include an indication of the change of the information sent on the NCH (see sub-clause 3.3.3.2).

The choice of the message type depends on the number of mobile stations to be paged and of the types of identities that are used. The maximum number of paged mobile stations per message is 4 when using only TMSIs for identification of the mobile stations.

The mobile station in idle mode is required to receive and analyse the paging messages and immediate assignment messages sent on the paging subchannel corresponding to its paging subgroup, as specified in 3GPP TS 45.002.

NOTE 3: The possible immediate assignment messages are: the IMMEDIATE ASSIGNMENT, the IMMEDIATE ASSIGNMENT EXTENDED and the IMMEDIATE ASSIGNMENT REJECT messages.

The paging and immediate assignment type messages contain a page mode information element. This information element controls possible additional requirements on mobile stations belonging to the paging subgroup corresponding to the paging subchannel the message was sent on. This implies that a given mobile station shall take into account the page mode information element of any message sent on its own paging subchannel whatever the nature of this message (paging messages or immediate assignment messages). This further implies that the mobile station does not take into account page mode information element of messages sent on paging subchannels other than its own paging subchannel. The requirements yielded by the page mode information element are as follows:

a) normal paging: no additional requirements;

b) extended paging: the mobile station is required in addition to receive and analyse the next but one message on the PCH;

c) paging reorganization: The mobile station shall receive all messages on the CCCH regardless of the BS-AG-BLKS-RES setting. It is required to receive all BCCH messages. When the mobile station receives the next message to its (possibly new) paging subgroup the subsequent action is defined in the page mode information element in that message;

d) same as before: No change of page mode from the previous page mode.

Note that a mobile station takes into account the page mode information only in messages of its own paging subchannel whatever the currently applied requirements (a, b, c or d).

When the mobile station selects a new PCH, the initial page mode in the mobile station shall be set to paging reorganization. If a message in the paging subchannel is not received correctly, the message is ignored and the previous page mode is assumed.

3.3.2.1.2 Paging initiation using paging subchannel on PCCCH

Paging initiation using a paging subchannel on PCCCH, see 3GPP TS 44.060, applies when sending paging information to a mobile station in packet idle mode and PCCCH is provided in the cell.

The paging initiation procedure and the paging request message used on PCCCH are specified in 3GPP TS 44.060.

3.3.2.1.3 Paging initiation using PACCH

Paging initiation using PACCH, see 3GPP TS 44.060, applies to a mobile station in packet transfer mode or in broadcast/multicast receive mode if so ordered by the network.

The paging initiation procedure and the message used to carry paging related information on PACCH are specified in 3GPP TS 44.060.

3.3.2.2 Paging response

Upon receipt of a paging request message, or other message containing information to trigger the establishment of a RR connection, and if access to the network is allowed, the addressed mobile station shall, when camped on a cell as specified in 3GPP TS 23.022, initiate the immediate assignment procedure as specified in sub-clause 3.3.1. The establishment of the main signalling link is then initiated by use of an SABM with information field containing the PAGING RESPONSE message (see sub-clause 3.1.5). The MM sublayer in the mobile station is informed that the RR entity has entered the dedicated mode.

If the PAGING RESPONSE message is being sent as part of a CS FallBack procedure, then the mobile station shall set the CSMT flag in the Additional Update Parameters IE.

Upon receipt of the PAGING RESPONSE message the network stops timer T3113. The MM sublayer in the network is informed that an RR connection exists.

3.3.2.3 Abnormal cases

Lower layer failure occurring during the immediate assignment procedure is treated as specified for that procedure.

If timer T3113 expires and a PAGING RESPONSE message has not been received, the network may repeat the paging request message and start timer T3113 again. The number of successive paging attempts is a network dependent choice.

Figure 3.3.2.3.1: Paging sequence

3.3.3 Notification procedure

The support of notification procedure is mandatory for mobile stations supporting "VGCS receive" and/or "VBS receive".

The network informs the mobile station of starting or on-going voice broadcast calls and voice group calls with the notification procedure.

In cases where the mobile station has initiated a VGCS call, if the channel mode modify procedure is applied to turn the dedicated channel into a VGCS channel and ciphering may be applied for that call, in this case the network should suspend transmission of notification messages until ciphering with the group cipher key has started on the group channel.

3.3.3.1 Notification of a call

The mobile station may receive a notification that a voice broadcast call or a voice group call is established. Notifications may be sent on the NCH, on the PCH, or on the FACCH when in dedicated mode or group receive mode. The presence of an NCH is indicated on the PCH in the Pi Rest Octets IE. A notification contains the group call reference and possibly other related information. This notification may be contained:

– in a NOTIFICATION/NCH message sent on the NCH to notify mobile stations of VBS or VGCS calls in the current cell, possibly together with a description of the related VBS or VGCS channel, and if the call is ciphered the value of the related VSTK_RAND and CELL_GLOBAL_COUNT. If talker priority is supported by the network then the notification shall contain the status of the emergency mode if the emergency mode is set and the priority uplink access method. When the notification is segmented over two Notification/NCH messages, the status of the emergency mode shall only be present in the block that contains the group channel description; If the group call is using AMR in the cell then this shall be indicated in the description of the VGCS/VBS channel together with an indication of whether the channel is FR or HR. The notification may indicate whether or not SMS data confidentiality and SMS guaranteed privacy are required.

– in a NOTIFICATION/FACCH message sent in unacknowledged mode on the main DCCH to notify mobile stations in dedicated mode or on the main DCCH of a VGCS or VBS channel, of another VBS or VGCS call in the current cell, possibly together with a description of the related VBS or VGCS channel, and if the call is ciphered the value of the related VSTK_RAND, CELL_GLOBAL_COUNT and bit 22 of COUNT (related to TDMA frame number as defined in 3GPP TS 43.020). If talker priority is supported by the network then the notification shall contain the status of the emergency mode and the priority uplink access method; The notification shall also contain the AMR codec configuration if the notifications contains a channel description that indicates that AMR is being used. The notification may indicate whether or not SMS data confidentiality and SMS guaranteed privacy are required.

– in the rest octets part of a PAGING REQUEST TYPE 1 message. The notification may contain a description of the related VBS or VGCS channel and if the call is ciphered the value of the related VSTK_RAND and the CELL_GLOBAL_COUNT. The notification shall also contain the AMR codec configuration if the notifications contains a channel description that indicates that AMR is being used.

If the contents of the notification cannot be contained within one message, then the notification can be segmented as described in 3.3.3.2.2.

When the network supports ciphered group calls the CELL_GLOBAL_COUNT shall be provided on the NCH. When the MS camps on a cell it should read the NCH and determine if CELL_GLOBAL_COUNT is provided.

When the MS obtains its CELL_GLOBAL_COUNT via a message on the main DCCH that contains the VGCS Ciphering Parameters information element, it must check if the CELL_GLOBAL_COUNT provided in the message is up to date by comparing bit 22 of COUNT in the message with the actual value of COUNT. If the value of bit 22 of COUNT in the message is ‘1’ but the actual value is ‘0’, then the value of CELL_GLOBAL_COUNT obtained from any of the above messages on the main DCCH shall be incremented by one (modulo 4).

The CELL_GLOBAL_COUNT is optionally transmitted in the Paging Request Type 1 message on the PCH and in the Notification/FACCH message when these messages contain a notification for a ciphered group call. If the group call is ciphered but the CELL_GLOBAL_COUNT is not provided in notification on the PCH, then the mobile station may obtain the CELL_GLOBAL_COUNT from the NCH, if not already obtained.

The notifications for ciphered group calls that contain a group channel description shall also contain the VSTK_RAND.

Once the MS has obtained the CELL_GLOBAL_COUNT for the serving cell it shall maintain its own copy of the parameter, incrementing the CELL_GLOBAL_COUNT by one (modulo 4) each time bit 22 of COUNT changes from ‘1’ to ‘0’.

Only one AMR codec configuration is allowed per cell for all VGCS/VBS calls using FR AMR and one for all VGCS/VBS calls using HR AMR.

A mobile station supporting neither VGCS listening nor VBS listening may ignore the notifications sent on the NCH or PCH. It may also ignore the notifications sent on the main DCCH except that a RR-STATUS message shall be sent to the network with cause #97, "message not existent or not implemented".

Upon receipt of every notification message a mobile station supporting VGCS listening or VBS listening shall give an indication containing the notified group call reference(s) to upper layers in the mobile station.

3.3.3.2 Joining a VGCS or VBS call

3.3.3.2.1 General

In order to join a VGCS or a VBS call the following procedures apply.

In this sub-clause, the term notification refers to the notification which has triggered the decision to join a VGCS or VBS call. The notification for one VGCS/VBS call may by segmented across two messages, as described in sub-clause 3.3.3.2.2.

If the notification on the main DCCH concerns a VBS or VGCS in the current cell and does not contain a description of the VGCS or VBS channel, the mobile station shall read the corresponding notification on the NCH. If the notification is for a VGCS/VBS call that is ciphered and contains a description of the VGCS or VBS channel but the ciphering mechanism parameters (VSTK_RAND or CELL_GLOBAL_COUNT) or the corresponding group key on the USIM are not available, then the notification shall be discarded.

If the description of the VGCS or VBS channel was included in the notification for the current cell, RR connection establishment shall not be initiated, instead, the mobile station shall enter the group receive mode, unless the group call is ciphered and the ciphering mechanism parameters (ie VSTK_RAND or CELL_GLOBAL_COUNT) or the corresponding group key on the USIM are not available. In this case the notification shall be discarded.

If no description for the VGCS or VBS channel is included in the notification, the mobile station shall establish a RR connection in dedicated mode in order to initiate the notification response procedure.

When the group call is ciphered then the MS shall calculate the ciphering keys for use on the group channel using the group key with the following parameters, as described in 3GPP TS 43.020:

– VSTK_RAND (provided in the notification);

– CELL_GLOBAL_COUNT (provided in the notification);

– Cell Global Identifier (CGI) (provided in system information type 3 and 4);

– Group Cipher Key Number (provided in the group call reference that is contained within the notification).

The group cipher keys need to be recalculated whenever CELL_GLOBAL_COUNT changes. The MS obtains the identity of its ciphering algorithm from its USIM, as described in 3GPP TS 43.020.

When the VGCS mobile station is allocated a dedicated channel that is ciphered, the channel shall be ciphered with the individual ciphering keys of this mobile station.

In the case that AMR is used on the VGCS/VBS group channel, the mobile station shall obtain the AMR codec configuration for the channel. This configuration may be obtained the notification/NCH, notification/FACCH, Notification/PCH, the Channel Release message or from the system information type 6 message. The network shall provide the configuration in the system information type 6 message if AMR is being used on the VGCS/VBS channel. Additionally, the mobile station shall set the codec configuration parameters Noise Suppression Control Bit (NSCB) and the Initial Codec Mode Indicator (ICMI) to 0 (see subclause 10.5.2.21aa, MultiRate configuration).

3.3.3.2.2 Segmentation of notifications

3.3.3.2.2.1 General

Segmented notifications are only applicable to ciphered group calls. The second segment is used to contain additional parameters related to the VGCS ciphering mechanism (VSTK_RAND, CELL_GLOBAL_COUNT).

Notifications can be segmented on the NCH, FACCH and PCH as described in the following sub-clauses. All segments of a segmented notification shall be transmitted and reassembled on the same logical channel (ie NCH, FACCH or PCH).

3.3.3.2.2.2 Segmentation of notifications on NCH

The first segment of a segmented notification on the NCH contains the following fields;

– Group call Reference with group channel description;

– Indication that the group call is a ciphered group call, as indicated by Group Cipher Key within the group call reference;

– Optionally CELL_GLOBAL_COUNT;

– Segment Id is set to 0;

– Status of the Emergency mode if talker priority is supported by the network and emergency mode is set;

– Priority uplink access method, if talker priority or sending of application data is supported by the network;

– Indication of whether AMR is being used (either FR or HR);

– Indication of whether or not SMS data confidentiality is required;

– Indication of whether or not SMS guaranteed privacy is required.

The second segment of a segmented notification on the NCH contains the following fields:

– Same Group call reference as first segment or a Reduced Group Call reference that contains the same group or broadcast call reference and service flag as contained in the Group Call Reference in the first segment.

– No group channel description;

– VSTK_RAND and optionally CELL_GLOBAL_COUNT;

– Segment Id is set to 1.

When the MS receives a segment of a segmented notification for a group call that it is a member of and for which no previous segment has been received, it shall store the received segment and start timer T3206 for the given group call. The MS shall stop timer T3206 in any of the following cases

– The MS joins another group call;

– The MS reselects to another cell;

– The value of NLN changes;

– The MS receives the missing segment.

If timer T3206 expires, or if the MS has to stop T3206 for any other reason than receiving the missing segment, the MS shall discard the associated stored segment. 3.3.3.2.2.3 Segmentation of notifications on FACCH

The first segment of a segmented notification on the FACCH contains the following fields;

– Group call reference with group channel description;

– Indication that the group call is a ciphered group call, as indicated by Group Cipher Key Number within the group call reference;

– Optionally CELL_GLOBAL_COUNT;

– Status of the Emergency mode if talker priority supported by the network ;

– Priority uplink access method for talker priority-related uplink access requests, if talker priority is supported by the network;

– AMR codec configuration, if the group channel description indicates that AMR is being used (either FR or HR);

– Indication of whether or not SMS data confidentiality is required;

– Indication of whether or not SMS guaranteed privacy is required.

The second segment of a segmented notification on the FACCH contains the following fields:

– Same group call reference as first segment, with no group channel description;

– VSTK_RAND and optionally CELL_GLOBAL_COUNT.

When the MS receives the first segment of a segmented notification for a group call that it is a member of, it shall store the received segment and start timer T3208 for the given group call. The MS shall stop timer T3208 in any of the following cases

– The MS joins another call;

– The MS performs handover to another cell;

– The MS receives the associated second segment;

– The MS receives a VGCS Reconfigure message.

If timer T3208 expires, or if the MS has to stop T3208 for any other reason than receiving the second segment, the MS shall discard the associated stored segment. If the MS wants to join this group call at expiry of T3208,it shall read the NCH to obtain the full description of the group call.

When the MS receives the second segment of a notification of a group call that it is member of before receiving the associated first segment then the MS shall discard the second segment. If the MS wants to join this group call it shall read the NCH to obtain the full description of the group call.

3.3.3.2.2.3 Segmentation of notifications on PCH

The first segment of a segmented notification on the PCH contains the following fields;

– Group call reference and group channel description;

– Indication that the group call is a ciphered group call, as indicated by Group Cipher Key within the group call reference;

– Optionally CELL_GLOBAL_COUNT;

– AMR codec configuration, if the group channel description indicates that AMR is being used (either FR or HR).

The MS determines that the message contains the first segment of a segmented notification if the message contains both an indication that the group call is ciphered and the group channel description, but does not contain the VSTK_RAND.

The second segment of a segmented notification on the PCH contains the following fields:

– Same group call reference as first segment, or reduced group call reference;

– VSTK_RAND and optionally CELL_GLOBAL_COUNT.

The MS determines that the message contains the second segment of a segmented notification if the message contains both an indication that the group call is ciphered and the VSTK_RAND, but does not contain the group channel description.

The MS shall only combine the first segment of the notification with the second segment if they have the same group call reference.

When the MS receives the first segment of a notification of a group call that it is member of but the second segment is not correctly received at the next but one PCH block after receiving the first segment, and the MS wants to join this group call, then the MS may either read further PCH blocks in an attempt to find the missing segment or read the NCH to obtain the full description of the group call. When the MS reads further blocks on the PCH to find the missing segment, the MS shall start timer T3210. If timer T3210 expires, the associated segment shall be discarded and the MS shall stop reading the PCH for the missing segment.

When the MS receives the second segment of a notification of a group call that it is member of before receiving the associated first segment, and the MS wants to join this group call, then the MS may either read further PCH blocks in an attempt to find the missing segment or read the NCH to obtain the full description of the group call. When the MS reads further blocks on the PCH to find the missing segment, the MS shall start timer T3210. If timer T3210 expires, the associated segment shall be discarded and the MS shall stop reading the PCH for the missing segment.

The MS shall stop timer T3210 if:

– The missing segment is correctly received;

– The MS leaves Idle mode (the MS discards the associated segment);

– The MS determines that notifications for another group call are being sent on the PCH (the MS discards the associated segment).

3.3.3.3 Reduced NCH monitoring mechanism

This sub-clause applies to mobile stations which read the NCH in idle mode in order to receive the notification messages for the voice broadcast call and the voice group call, which read the PCH or PPCH to receive pagings and which aim at reducing the reception load.

A reduced NCH monitoring mechanism shall be used on the NCH. When the mobile station in idle mode enters a cell and deduces from the BCCH that an NCH is present, it shall read the NCH until it has received at least two messages on the NCH indicating NLN, with the two last received NLN being identical. Then it may stop reading the NCH until it receives on the PCH an NLN(PCH) different from the last previously received NLN or on the SACCH an NLN(SACCH) different from the last previously received NLN or on the PPCH an NLN(PPCH) different from the last previously received NLN.

For this, parameters are provided:

NLN: Notification List Number. The NLN is a modulo 4 counter. A change of NLN indicates that new notifications are provided on the NCH. The network shall ensure that a mobile station receives the NLN as often as necessary for a good functioning of the reduced monitoring.

NLN status: The NLN status is a single bit field which indicates the status of the content of the NOTIFICATION/NCH messages for a particular NLN value. A change of the NLN status field indicates a change of information on the NCH which is not related to new calls (e.g. There may have been a release of a previous notified call, a change in status of the emergency mode etc…).

The network has to provide both NLN and NLN status parameters.

These parameters are defined on the NCH, PCH, SACCH and PPCH:

NLN(NCH): Notification List Number (contained in certain NOTIFICATION messages on the NCH as required by the reduced NCH monitoring function).

NLN(PCH): Notification List Number (contained in all PAGING REQUEST TYPE 2 messages, PAGING REQUEST TYPE 3 messages and those PAGING REQUEST TYPE 1 messages with P1 rest octets value part of length >=1 on the PCH).

NLN(SACCH): Notification List Number (contained in all SYSTEM INFORMATION TYPE 6 messages on the SACCH when there are NCH blocks allocated ).

NLN(PPCH): Notification List Number (contained in all PACKET PAGING REQUEST messages containing at least one page request for an RR connection establishment and optionally contained in other PACKET PAGING REQUEST messages).

NLN status(PCH): NLN status (contained in all PAGING REQUEST TYPE 2 messages, PAGING REQUEST TYPE 3 messages and those PAGING REQUEST TYPE 1 messages with P1 rest octets value part of length >=1 on the PCH).

NLN status(SACCH): NLN status (contained in all SYSTEM INFORMATION TYPE 6 messages on the SACCH when there are NCH blocks allocated).

NLN status(PPCH): NLN status (contained in all PACKET PAGING REQUEST messages containing at least one page request for an RR connection establishment and optionally contained in other PACKET PAGING REQUEST messages).

When there are no VGCS or VBS calls active in the cell, the network shall transmit notification messages with an empty notification list (not necessarily in every NCH block) but with NLN(NCH).

A mobile station supporting neither VGCS listening nor VBS listening shall ignore the NLN(NCH),NLN(PCH), NLN(SACCH), NLN(PPCH) and NLN status fields.

If a mobile station (supporting VGCS listening and/or VBS listening) receives a NLN parameters on the NLN(PCH) or NLN(SACCH) or NLN(PPCH) field different from the last received NLN value it shall read the NCH until it has received at least two messages on the NCH indicating NLN with the two last received NLN being identical.

If a message in the paging subchannel on CCCH is not received correctly, or if a paging message on CCCH does not contain the information on the notification status, the mobile station shall read the NCH until it has received at least two messages on the NCH indicating NLN, with the two last received NLN being identical.

If a message in the paging subchannel on PCCCH is not received correctly and the mobile station has previously received notification status on PCCCH in that cell, the mobile station shall read the NCH until it has received at least two messages on the NCH indicating NLN, with the two last received NLN being identical.

If a packet paging message on PCCCH contains at least one page request for an RR connection establishment and does not contain the information on the notification status, the mobile station shall assume that information on the notification status on PCCCH is not provided in this cell. In this case the mobile shall perform reduced NCH mechanism by reading NLN(PCH) and NLN status(PCH) on PCH until the MS received information on the notification status on PCCCH.

3.3.3.4 Notification response procedure

In order to initiate the notification response procedure, if access to the network is allowed, the mobile station shall, when camped on a cell as specified in 3GPP TS 43.022, initiate the immediate assignment procedure as specified in 3.3.1. The establishment of the main signalling link is then initiated by use of an SABM with information field containing the NOTIFICATION RESPONSE message (see sub-clause 3.1.5). The Group or Broadcast Call Reference and the Service Flag in the Descriptive Group or Broadcast Call Reference Information Element shall be identical as received in the corresponding IE in the notification or paging messages. The MM sublayer in the mobile station is informed that the RR entity has entered the dedicated mode.

Upon receipt of the NOTIFICATION RESPONSE message the network stops timer T3101. The MM sublayer in the network may be informed that an RR connection exists; in this case, the MM sublayer may initiate MM common procedures.

The network may use the dedicated connection to order the mobile station to enter the group receive mode.