6.4 Network initiated ESM procedures

24.3013GPPNon-Access-Stratum (NAS) protocol for Evolved Packet System (EPS)Release 18Stage 3TS

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

6.4.1 Default EPS bearer context activation procedure

6.4.1.1 General

The purpose of the default bearer context activation procedure is to establish a default EPS bearer context between the UE and the EPC. The default EPS bearer context activation procedure is initiated by the network as a response to the PDN CONNECTIVITY REQUEST message from the UE. The default bearer context activation procedure can be part of the attach procedure, and if the attach procedure fails, the UE shall consider that the default bearer activation has implicitly failed. The default EPS bearer context does not have any TFT assigned during the activation procedure. This corresponds to using a match-all packet filter. The network may at anytime after the establishment of this bearer assign a TFT to the default EPS bearer and may subsequently modify the TFT or the packet filters of this default bearer.

6.4.1.2 Default EPS bearer context activation initiated by the network

The MME shall initiate the default bearer context activation procedure by sending an ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message and enter the state BEARER CONTEXT ACTIVE PENDING (see example in figure 6.4.1.2.1). When the default bearer is activated as part of the attach procedure, the MME shall send the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message together with ATTACH ACCEPT and shall not start the timer T3485. When the default bearer is activated as the response to a stand-alone PDN CONNECTIVITY REQUEST message apart from the attach procedure, the MME shall send the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message alone, and start the timer T3485.

The MME shall assign and include an EPS bearer identity in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message selecting a value as specified by clause 9.3.2. The MME shall retrieve the PTI from the PDN CONNECTIVITY REQUEST message and include it in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message. Both the network identifier part and the operator identifier part shall be included in the Access Point Name IE.

Figure 6.4.1.2.1: Default EPS bearer context activation procedure

6.4.1.3 Default EPS bearer context activation accepted by the UE

Upon receipt of the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, if the UE provided an APN for the establishment of the PDN connection, the UE shall stop timer T3396 if it is running for the APN provided by the UE. If the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall stop the timer T3396 associated with no APN if it is running. If the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message was received in response to a request for an emergency PDN connection, the UE shall not stop the timer T3396 associated with no APN if it is running. For any case, the UE shall then send an ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT message and enter the state BEARER CONTEXT ACTIVE. When the default bearer is activated as part of the attach procedure, the UE shall send the ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT message together with ATTACH COMPLETE message. When the default bearer is activated as the response to the stand-alone PDN CONNECTIVITY REQUEST message, the UE shall send the ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT message alone.

If a WLAN offload indication information element is included in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall store the WLAN offload acceptability values for this PDN connection and use the E-UTRAN offload acceptability value to determine whether this PDN connection is offloadable to WLAN or not.

The UE checks the PTI in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message to identify the UE requested PDN connectivity procedure to which the default bearer context activation is related (see clause 6.5.1).

If the UE receives a serving PLMN rate control IE in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall store the serving PLMN rate control IE value and use the stored serving PLMN rate control value as the maximum allowed limit of uplink User data container IEs included in ESM DATA TRANSPORT messages for the corresponding PDN connection in accordance with 3GPP TS 23.401 [10].

If the UE receives an APN rate control parameters container in the protocol configuration options IE or extended protocol configuration options IE in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall store the APN rate control parameters value and use the stored APN rate control parameters value as the maximum allowed limit of uplink user data related to the APN indicated in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message in accordance with 3GPP TS 23.401 [10]. If the UE has a previously stored APN rate control parameters value for this APN, the UE shall replace the stored APN rate control parameters value for this APN with the received APN rate control parameters value.

If the UE receives an additional APN rate control parameters for exception data container in the protocol configuration options IE or extended protocol configuration options IE in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall store the additional APN rate control parameters for exception data value and use the stored additional APN rate control parameters for exception data value as the maximum allowed limit of uplink exception data related to the APN indicated in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message in accordance with 3GPP TS 23.401 [10]. If the UE has a previously stored additional APN rate control parameters for exception data value for this APN, the UE shall replace the stored additional APN rate control parameters for exception data value for this APN with the received additional APN rate control parameters for exception data value.

If the UE receives a small data rate control parameters container in the protocol configuration options IE or the extended protocol configuration options IE in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall store the small data rate control parameters value and use the stored small data rate control parameters value as the maximum allowed limit of uplink user data for the corresponding PDU session that becomes transferred after inter-system change from S1 mode to N1 mode in accordance with 3GPP TS 23.501 [58].

If the UE receives non-IP Link MTU parameter, Ethernet Frame Payload MTU parameter, IPv4 Link MTU parameter, or Unstructured Link MTU parameter of the protocol configuration options IE or of the extended protocol configuration options IE in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall pass the received Non-IP Link MTU size, Ethernet Frame Payload MTU size, or IPv4 Link MTU size, or Unstructured Link MTU size to the upper layer.

NOTE 1: The Non-IP Link MTU and the IPv4 Link MTU size correspond to the maximum length of user data that can be sent either in the user data container in the ESM DATA TRANSPORT message or via S1-U interface.

NOTE 2: The Ethernet frame payload MTU size corresponds to the maximum length of a payload of an Ethernet frame that can be sent either in the user data container in the ESM DATA TRANSPORT message or via S1-U interface.

NOTE 3: A PDN connection of non-IP PDN type can be transferred to a PDU session of "Unstructured" PDU session type, thus the UE can request the unstructured link MTU parameter in the default EPS bearer context activation procedure. The unstructured link MTU size correspond to the maximum length of user data packet that can be sent either via the control plane or via N3 interface for a PDU session of the "Unstructured" PDU session type as specified in 3GPP TS 24.501 [54].

If the UE receives the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message containing the Uplink data not allowed parameter in the extended protocol configuration options IE, then the UE shall not send any uplink user data over EPS bearer context(s) of the corresponding PDN connection.

Editor’s note (CR#3853, TEI18_SDNAEPC): It is FFS whether the Extended protocol configuration options IE in the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message and the ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT message can be used for exchanging the SDNAEPC EAP message.

Upon receiving the DNS server security information, the UE shall pass it to the upper layer. The UE shall use this information to send the DNS over (D)TLS (See 3GPP TS 33.501 [24]).

NOTE 4: Support of DNS over (D)TLS is based on the informative requirements as specified in 3GPP TS 33.501 [24].

If the UE supports provisioning of ECS configuration information to the EEC in the UE, then upon receiving:

– at least one of ECS IPv4 address(es), ECS IPv6 address(es), ECS FQDN(s);

– at least one associated ECSP identifier; and

– optionally spatial validity conditions associated with the ECS address

in the Extended protocol configuration options IE of the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message, the UE shall pass them to the upper layers.

NOTE 5: The IP address(es) and/or FQDN(s) are associated with the ECSP identifier and replace previously provided ECS configuration information associated with the same ECSP identifier, if any.Upon receipt of the ACTIVATE DEFAULT EPS BEARER CONTEXT ACCEPT message, the MME shall enter the state BEARER CONTEXT ACTIVE and stop the timer T3485, if the timer is running. If the PDN CONNECTIVITY REQUEST message included a low priority indicator set to "MS is configured for NAS signalling low priority", the MME shall store the NAS signalling low priority indication within the default EPS bearer context.

6.4.1.4 Default EPS bearer context activation not accepted by the UE

If the default EPS bearer context activation is part of the attach procedure, the ESM sublayer shall notify the EMM sublayer of an ESM failure. If EMM-REGISTERED without PDN connection is supported by the UE and the MME, the ESM sublayer shall additionally provide an ACTIVATE DEFAULT EPS BEARER CONTEXT REJECT message to the EMM sublayer.

If the default EPS bearer context activation is not part of the attach procedure, the UE shall send an ACTIVATE DEFAULT EPS BEARER CONTEXT REJECT message and enter the state BEARER CONTEXT INACTIVE.

The ACTIVATE DEFAULT EPS BEARER CONTEXT REJECT message contains an ESM cause that typically indicates one of the following cause values:

#26: insufficient resources;

#31: request rejected, unspecified; or

#95 – 111: protocol errors.

Upon receipt of the ACTIVATE DEFAULT EPS BEARER CONTEXT REJECT message, the MME shall enter the state BEARER CONTEXT INACTIVE and stop the timer T3485, if the timer is running.

6.4.1.5 Abnormal cases in the UE

The following abnormal cases can be identified:

a) Default EPS bearer context activation request for an already activated default EPS bearer context:

If the UE receives an ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message with an EPS bearer identity identical to the EPS bearer identity of an already activated default EPS bearer context, the UE shall locally deactivate the existing default EPS bearer context and all the associated dedicated EPS bearer contexts, if any, and proceed with the requested default EPS bearer context activation.

b) Default EPS bearer context activation request for an already activated dedicated EPS bearer context:

If the UE receives an ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST message with an EPS bearer identity identical to the EPS bearer identity of an already activated dedicated EPS bearer context, the UE shall locally deactivate the existing dedicated EPS bearer context and proceed with the requested default EPS bearer context activation.

6.4.1.6 Abnormal cases on the network side

The following abnormal cases can be identified:

a) Expiry of timer T3485:

On the first expiry of the timer T3485, the MME shall resend the ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST and shall reset and restart timer T3485. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3485, the MME shall release possibly allocated resources for this activation and shall abort the procedure.

b) Lower layer indicates that the HeNB rejected the establishment of the default bearer (see 3GPP TS 36.413 [23]) for a LIPA PDN connection or SIPTO at the local network PDN connection due to a triggered handover:

The MME shall enter the state BEARER CONTEXT INACTIVE, stop timer T3485 and reject the PDN connectivity request procedure including the ESM cause value #34 "service option temporarily out of order" in the PDN CONNECTIVITY REJECT message. The MME shall release possibly allocated resources for this activation.

6.4.2 Dedicated EPS bearer context activation procedure

6.4.2.1 General

The purpose of the dedicated EPS bearer context activation procedure is to establish an EPS bearer context with specific QoS and TFT between the UE and the EPC.

In WB-S1 mode, the dedicated EPS bearer context activation procedure is initiated by the network, but may be requested by the UE by means of the UE requested bearer resource allocation procedure (see clause 6.5.3) or the UE requested bearer resource modification procedure (see clause 6.5.4). The dedicated bearer context activation procedure can be part of the attach procedure or be initiated together with the default EPS bearer context activation procedure when the UE initiated stand-alone PDN connectivity procedure. If the attach procedure or the default EPS bearer context activation procedure fails, the UE shall consider that the dedicated bearer activation has implicitly failed. The network may initiate the dedicated EPS bearer context activation procedure together with the completion of the service request procedure.

In NB-S1 mode, the dedicated EPS bearer contexts activation procedure is not used.

Upon an inter-system mobility from WB-S1 mode to NB-S1 mode in EMM-IDLE mode, if the UE has at least one dedicated EPS bearer context in ESM state BEARER CONTEXT ACTIVE, the UE shall locally deactivate any such dedicated EPS bearer context and shall include the EPS bearer context status IE in TRACKING AREA UPDATE REQUEST message.

Upon an inter-system change from WB-N1 mode to NB-S1 mode in EMM-IDLE mode for the UE operating in single-registration mode, the UE shall set each mapped dedicated EPS bearer context, if any, to ESM state BEARER CONTEXT INACTIVE and shall then include the EPS bearer context status IE in the TRACKING AREA UPDATE REQUEST message.

NOTE: 3GPP TS 23.060 [74] clause 9.3 specifies that a packet filter applicable for the downlink direction is not mandatory in a TFT.

6.4.2.2 Dedicated EPS bearer context activation initiated by the network

In WB-S1 mode, the MME shall initiate the dedicated bearer context activation procedure by sending an ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, start the timer T3485, and enter the state BEARER CONTEXT ACTIVE PENDING (see example in figure 6.4.2.2.1).

The MME allocates the EPS bearer identity selecting a value as specified by clause 9.3.2, and includes it in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message. The MME shall include the EPS bearer identity of the associated default bearer as the linked EPS bearer identity in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message. If this procedure was initiated by a UE requested bearer resource allocation procedure or a UE requested bearer resource modification procedure, the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST shall contain the procedure transaction identity (PTI) value received by the MME in the BEARER RESOURCE ALLOCATION REQUEST or BEARER RESOURCE MODIFICATION REQUEST respectively.

Figure 6.4.2.2.1: Dedicated EPS bearer context activation procedure

6.4.2.3 Dedicated EPS bearer context activation accepted by the UE

Upon receipt of the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, if the UE provided an APN for the establishment of the PDN connection, the UE shall stop timer T3396, if it is running for the APN provided by the UE. If the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall stop the timer T3396 associated with no APN if it is running. If the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message was received for an emergency PDN connection, the UE shall not stop the timer T3396 associated with no APN if it is running. For any case, the UE shall then check the received TFT before taking it into use, send an ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT message and enter the state BEARER CONTEXT ACTIVE. The ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT message shall include the EPS bearer identity.

The linked EPS bearer identity included in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message indicates to the UE to which default bearer, IP address and PDN the dedicated bearer is linked.

If the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message contains a PTI value other than "no procedure transaction identity assigned" and "reserved" (see 3GPP TS 24.007 [12]), the UE uses the PTI to identify the UE requested bearer resource allocation procedure or the UE requested bearer resource modification procedure to which the dedicated bearer context activation is related.

If the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message contains a PTI value other than "no procedure transaction identity assigned" and "reserved" (see 3GPP TS 24.007 [12]) and the PTI is associated to a UE requested bearer resource allocation procedure or a UE requested bearer resource modification procedure, the UE shall release the traffic flow aggregate description associated to the PTI value provided.

The UE shall use the received TFT to apply mapping of uplink traffic flows to the radio bearer.

The UE shall treat any packet filter without explicit direction as being bi-directional.

If the UE receives an APN rate control parameters container in the protocol configuration options IE or extended protocol configuration options IE in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE shall store the APN rate control parameters value and use the stored APN rate control parameters value as the maximum allowed limit of uplink user data related to the corresponding APN in accordance with 3GPP TS 23.401 [10]. If the UE has a previously stored APN rate control parameters value for this APN, the UE shall replace the stored APN rate control parameters value for this APN with the received APN rate control parameters value.

If the UE receives an additional APN rate control parameters for exception data container in the protocol configuration options IE or extended protocol configuration options IE in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE shall store the additional APN rate control parameters for exception data value and use the stored additional APN rate control parameters for exception data value as the maximum allowed limit of uplink exception data related to the corresponding APN in accordance with 3GPP TS 23.401 [10]. If the UE has a previously stored additional APN rate control parameters for exception data value for this APN, the UE shall replace the stored additional APN rate control parameters for exception data value for this APN with the received additional APN rate control parameters for exception data value.

If the UE receives a small data rate control parameters container in the protocol configuration options IE or the extended protocol configuration options IE in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE shall store the small data rate control parameters value and use the stored small data rate control parameters value as the maximum allowed limit of uplink user data for the corresponding PDU session that becomes transferred after inter-system change from S1 mode to N1 mode in accordance with 3GPP TS 23.501 [58]. If the UE has a previously stored small data rate control parameters value for this PDU session, the UE shall replace the stored small data rate control parameters value for this PDU Session with the received small data rate control parameters value.

If the UE receives an additional small data rate control parameters for exception data container in the protocol configuration options IE or the extended protocol configuration options IE in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE shall store the additional small data rate control parameters for exception data value and use the stored additional small data rate control parameters for exception data value as the maximum allowed limit of uplink exception data for the corresponding PDU session that becomes transferred after inter-system change from S1 mode to N1 mode in accordance with 3GPP TS 23.501 [58]. If the UE has a previously stored additional small data rate control parameters for exception data value for this PDU session, the UE shall replace the stored additional small data rate control parameters for exception data value for this PDU session with the received additional small data rate control parameters for exception data value.

If the UE receives QoS rule(s) of the 5GS QoS flow(s), which corresponds to the dedicated EPS bearer being activated, in the protocol configuration options IE or the extended protocol configuration options IE of the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE stores the QoS rule(s) for use during inter-system change from S1 mode to N1 mode.

Upon receipt of the ACTIVATE DEDICATED EPS BEARER CONTEXT ACCEPT message, the MME shall stop the timerT3485 and enter the state BEARER CONTEXT ACTIVE.

6.4.2.4 Dedicated EPS bearer context activation not accepted by the UE

Upon receipt of the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE may reject the request from the MME by sending an ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT message. The message shall include the EPS bearer identity and an ESM cause value indicating the reason for rejecting the dedicated EPS bearer context activation request.

The ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT message contains an ESM cause that typically indicates one of the following ESM cause values:

#26: insufficient resources;

#31: request rejected, unspecified;

#41: semantic error in the TFT operation;

#42: syntactical error in the TFT operation;

#43: invalid EPS bearer identity;

#44: semantic error(s) in packet filter(s);

#45: syntactical error(s) in packet filter(s); or

#95 – 111: protocol errors.

The UE shall check the TFT in the request message for different types of TFT IE errors as follows:

a) Semantic errors in TFT operations:

1) When the TFT operation is an operation other than "Create a new TFT"

The UE shall reject the activation request with ESM cause #41 "semantic error in the TFT operation".

b) Syntactical errors in TFT operations:

1) When the TFT operation = "Create a new TFT" and the packet filter list in the TFT IE is empty.

2) When there are other types of syntactical errors in the coding of the TFT IE, such as a mismatch between the number of packet filters subfield, and the number of packet filters in the packet filter list.

The UE shall reject the activation request with ESM cause #42 "syntactical error in the TFT operation".

c) Semantic errors in packet filters:

1) When a packet filter consists of conflicting packet filter components which would render the packet filter ineffective, i.e. no IP packet will ever fit this packet filter. How the UE determines a semantic error in a packet filter is outside the scope of the present document.

2) When the resulting TFT does not contain any packet filter which applicable for the uplink direction.

The UE shall reject the activation request with ESM cause #44 "semantic errors in packet filter(s)".

d) Syntactical errors in packet filters:

1) When the TFT operation = "Create a new TFT" and two or more packet filters in the resultant TFT would have identical packet filter identifiers.

2) When the TFT operation = "Create a new TFT" and two or more packet filters in all TFTs associated with this PDN connection would have identical packet filter precedence values.

3) When there are other types of syntactical errors in the coding of packet filters, such as the use of a reserved value for a packet filter component identifier.

In case 2, if the old packet filters do not belong to the default EPS bearer context, the UE shall not diagnose an error, shall further process the new activation request and, if it was processed successfully, shall delete the old packet filters which have identical filter precedence values. Furthermore, by means of explicit peer-to-peer signalling between the network and the UE, the UE shall perform a UE requested bearer resource modification procedure to delete the packet filters in the network corresponding to the packet filters it has deleted on the UE side.

In case 2, if one or more old packet filters belong to the default EPS bearer context, the UE shall release the relevant PDN connection. If the relevant PDN connection is the last one that the UE has and EMM-REGISTERED without PDN connection is not supported by the UE or the MME, the UE shall detach and re-attach to the network.

In cases 1 and 3 the UE shall reject the activation request with ESM cause #45 "syntactical errors in packet filter(s)".

Upon receipt of the ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT message in state BEARER CONTEXT ACTIVE PENDING, the MME shall stop the timer T3485, enter the state BEARER CONTEXT INACTIVE and abort the dedicated EPS bearer context activation procedure. The MME also requests the lower layer to release the radio resources that were established during the dedicated EPS bearer context activation procedure.

6.4.2.5 Abnormal cases in the UE

The following abnormal cases can be identified:

a) Dedicated EPS bearer context activation request for an already activated default EPS bearer context:

If the UE receives an ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message with an EPS bearer identity identical to the EPS bearer identity of an already activated default EPS bearer context, the UE shall locally deactivate the existing default EPS bearer context and all the associated dedicated EPS bearer contexts, if any, and proceed with the requested dedicated EPS bearer context activation.

b) Dedicated EPS bearer context activation request for an already activated dedicated EPS bearer context

If the UE receives an ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message with an EPS bearer identity identical to the EPS bearer identity of an already activated dedicated EPS bearer context, the UE shall locally deactivate the existing dedicated EPS bearer context and proceed with the requested dedicated EPS bearer context activation.

c) No default EPS bearer context with linked EPS bearer identity activated

If the linked EPS bearer identity included in the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message does not match the EPS bearer identity of any activated default EPS bearer context, the UE shall reply with an ACTIVATE DEDICATED EPS BEARER CONTEXT REJECT message with ESM cause #43 "invalid EPS bearer identity".

d) Dedicated EPS bearer context activation request when the PLMN’s maximum number of EPS bearer contexts in S1 mode is reached at the UE:

If the PLMN’s maximum number of EPS bearer contexts in S1 mode is reached at the UE and the UE receives an ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST message, the UE shall clear the determination representing the PLMN’s maximum number of EPS bearer contexts in S1 mode and proceed with the dedicated EPS bearer context activation procedure.

6.4.2.6 Abnormal cases on the network side

The following abnormal cases can be identified:

a) Expiry of timer T3485:

On the first expiry of the timer T3485, the MME shall resend the ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST and shall reset and restart timer T3485. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3485, the MME shall abort the procedure, release any resources allocated for this activation and enter the state BEARER CONTEXT INACTIVE.

b) Collision of UE requested PDN disconnect procedure and dedicated EPS bearer context activation procedure:

When the MME receives a PDN DISCONNECT REQUEST message during the dedicated EPS bearer context activation procedure, and the EPS bearer to be activated belongs to the PDN connection the UE wants to disconnect, the MME shall terminate the dedicated bearer context activation procedure locally, release any resources related to this procedure and proceed with the PDN disconnect procedure.

6.4.3 EPS bearer context modification procedure

6.4.3.1 General

The purpose of the EPS bearer context modification procedure is to modify an EPS bearer context with a specific QoS and TFT, or re-negotiate header compression configuration associated to an EPS bearer context. The EPS bearer context modification procedure is initiated by the network, but it may also be initiated as part of the UE requested bearer resource allocation procedure or the UE requested bearer resource modification procedure.

The network may also initiate the EPS bearer context modification procedure to update the Measurement Assistance Information. See clause 4.4 of 3GPP TS 24.193 [61].

The network may also initiate the EPS bearer context modification procedure to update the APN-AMBR of the UE, for instance after an inter-system handover. See 3GPP TS 23.401 [10] annex E.

The MME may also initiate the EPS bearer context modification procedure to update the WLAN offload indication to the UE, for instance after the MME received an updated WLAN offload indication of a PDN Connection from HSS. See 3GPP TS 23.401 [10] clause 4.3.23.

The MME may also initiate the EPS bearer context modification procedure to update information required for inter-system change from S1 mode to N1 mode (e.g. session-AMBR, QoS rule(s)). See 3GPP TS 24.501 [54].

The network may initiate the EPS bearer context modification procedure together with the completion of the service request procedure.

The network may initiate the EPS bearer context modification procedure to initiate the procedure for the UUAA-SM for the UAS services.

6.4.3.2 EPS bearer context modification initiated by the network

The MME shall initiate the EPS bearer context modification procedure by sending a MODIFY EPS BEARER CONTEXT REQUEST message to the UE, starting the timer T3486, and entering the state BEARER CONTEXT MODIFY PENDING (see example in figure 6.4.3.2.1).

The MME shall include an EPS bearer identity that identifies the EPS bearer context to be modified in the MODIFY EPS BEARER CONTEXT REQUEST message.

If this procedure was initiated by a UE requested bearer resource allocation procedure or a UE requested bearer resource modification procedure, the MODIFY EPS BEARER CONTEXT REQUEST shall contain the procedure transaction identity (PTI) value received by the MME in the BEARER RESOURCE ALLOCATION REQUEST or BEARER RESOURCE MODIFICATION REQUEST respectively.

If the UE indicated "Control plane CIoT EPS optimization supported" and "Header compression for control plane CIoT EPS optimization supported" in the UE network capability IE in the latest ATTACH REQUEST message or the TRACKING AREA UPDATE REQUEST message, and the MME supports Control plane CIoT EPS optimization and Header compression for control plane CIoT EPS optimization, the MME may include the Header compression configuration IE in the MODIFY EPS BEARER CONTEXT REQUEST message to re-negotiate header compression configuration associated to an EPS bearer context.

Figure 6.4.3.2.1: EPS bearer context modification procedure

6.4.3.3 EPS bearer context modification accepted by the UE

Upon receipt of the MODIFY EPS BEARER CONTEXT REQUEST message, if the UE provided an APN for the establishment of the PDN connection, the UE shall stop timer T3396, if it is running for the APN provided by the UE. If the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall stop the timer T3396 associated with no APN if it is running. If the MODIFY EPS BEARER CONTEXT REQUEST message was received for an emergency PDN connection, the UE shall not stop the timer T3396 associated with no APN if it is running. For any case, the UE shall then check the received TFT before taking it into use and send a MODIFY EPS BEARER CONTEXT ACCEPT message to the MME.

If the MODIFY EPS BEARER CONTEXT REQUEST message contains a PTI value other than "no procedure transaction identity assigned" and "reserved" (see 3GPP TS 24.007 [12]), the UE uses the PTI to identify the UE requested bearer resource allocation procedure or the UE requested bearer resource modification procedure to which the EPS bearer context modification is related (see clause 6.5.3 and clause 6.5.4).

If the MODIFY EPS BEARER CONTEXT REQUEST message contains a PTI value other than "no procedure transaction identity assigned" and "reserved" (see 3GPP TS 24.007 [12]) and the PTI is associated to a UE requested bearer resource allocation procedure or a UE requested bearer resource modification procedure, the UE shall release the traffic flow aggregate description associated to the PTI value provided.

If the EPS bearer context that is modified is a GBR bearer and the MODIFY EPS BEARER CONTEXT REQUEST message does not contain the Guaranteed Bit Rate (GBR) and the Maximum Bit Rate (MBR) values for uplink and downlink, the UE shall continue to use the previously received values for the Guaranteed Bit Rate (GBR) and the Maximum Bit Rate (MBR) for the corresponding bearer.

The UE shall use the received TFT to apply mapping of uplink traffic flows to the radio bearer if the TFT contains packet filters for the uplink direction.

If a WLAN offload indication information element is included in the MODIFY EPS BEARER CONTEXT REQUEST message, the UE shall store the WLAN offload acceptability values for this PDN connection and use the E-UTRAN offload acceptability value to determine whether this PDN connection is offloadable to WLAN or not.

If the UE receives an APN rate control parameters container in the protocol configuration options IE or extended protocol configuration options IE in the MODIFY EPS BEARER CONTEXT REQUEST message, the UE shall store the APN rate control parameters value and use the stored APN rate control parameters value as the maximum allowed limit of uplink user data related to the corresponding APN in accordance with 3GPP TS 23.401 [10]. If the UE has a previously stored APN rate control parameters value for this APN, the UE shall replace the stored APN rate control parameters value for this APN with the received APN rate control parameters value.

If the UE receives an additional APN rate control parameters for exception data container in the protocol configuration options IE or extended protocol configuration options IE in the MODIFY EPS BEARER CONTEXT REQUEST message, the UE shall store the additional APN rate control parameters for exception data value and use the stored additional APN rate control parameters for exception data value as the maximum allowed limit of uplink exception data related to the corresponding APN in accordance with 3GPP TS 23.401 [10]. If the UE has a previously stored additional APN rate control parameters for exception data value for this APN, the UE shall replace the stored additional APN rate control parameters for exception data value for this APN with the received additional APN rate control parameters for exception data value.

If the UE receives a small data rate control parameters container in the protocol configuration options IE or the extended protocol configuration options IE in the MODIFY EPS BEARER CONTEXT REQUEST message, the UE shall store the small data rate control parameters value and use the stored small data rate control parameters value as the maximum allowed limit of uplink user data for the corresponding PDU session that becomes transferred after inter-system change from S1 mode to N1 mode in accordance with 3GPP TS 23.501 [58]. If the UE has a previously stored small data rate control parameters value for this PDU session, the UE shall replace the stored small data rate control parameters value for this PDU Session with the received small data rate control parameters value.

If the UE receives an additional small data rate control parameters for exception data container in the protocol configuration options IE or the extended protocol configuration options IE in the MODIFY EPS BEARER CONTEXT REQUEST message, the UE shall store the additional small data rate control parameters for exception data value and use the stored additional small data rate control parameters for exception data value as the maximum allowed limit of uplink exception data for the corresponding PDU session that becomes transferred after inter-system change from S1 mode to N1 mode in accordance with 3GPP TS 23.501 [58]. If the UE has a previously stored additional small data rate control parameters for exception data value for this PDU session, the UE shall replace the stored additional small data rate control parameters for exception data value for this PDU session with the received additional small data rate control parameters for exception data value.

Upon receipt of the MODIFY EPS BEARER CONTEXT REQUEST message with a session-AMBR and QoS rule(s) in the protocol configuration options IE or the extended protocol configuration options IE, the UE stores the session-AMBR and QoS rule(s) for use during inter-system change from S1 mode to N1 mode.

If the UE receives the MODIFY EPS BEARER CONTEXT REQUEST message containing the Uplink data allowed parameter in the extended protocol configuration options IE, then the UE may start transmitting uplink user data over EPS bearer context(s) of the corresponding PDN connection. The MODIFY EPS BEARER CONTEXT REQUEST message as a part of authorization procedure for the C2 communication, can include an extended protocol configuration options IE containing the service-level-AA container with the length of two octets. The service-level-AA container with the length of two octets:

a) contains the service-level-AA response with the C2AR field set to the C2 authorization result informed by the UAS NF;

b) can contain the service-level-AA payload parameter set to the C2 authorization payload and the service-level-AA payload type parameter set to "C2 authorization payload"; and

c) can contain the service-level device ID with the value set to a new CAA-level UAV ID.

NOTE 1: The C2 authorization payload in the service-level-AA payload can include the C2 pairing information and the C2 session security information.

If the EPS bearer context being modified is associated with a PDN connection for UAS services and the MODIFY EPS BEARER CONTEXT REQUEST message includes the service-level-AA container with the length of two octets in the Extended protocol configuration options IE, the UE supporting UAS services shall forward the contents of the service-level-AA container with the length of two octets to the upper layers.

If the EPS bearer context being modified is associated with a PDN connection for UAS services, the MODIFY EPS BEARER CONTEXT REQUEST message includes the extended protocol configuration options IE containing the service-level-AA container with the length of two octets containing the service-level-AA response parameter with the SLAR field set to "Service level authentication and authorization was successful", the UE supporting UAS services:

a) shall consider the UUAA procedure as successfully completed and provide the service-level-AA response to the upper layers;

b) if the service-level-AA container with the length of two octets contains the service-level device ID parameter carrying a CAA-level UAV ID, shall provide the CAA-level UAV ID to the upper layers; and

c) if the service-level-AA container with the length of two octets contains the service-level-AA payload type parameter with the value "UUAA payload" and the service-level-AA payload parameter carrying the UUAA payload, shall provide the UUAA payload to the upper layers.

Upon reception of a service-level-AA payload from the upper layers, the UE supporting UAS services shall include the extended protocol configuration options IE in the MODIFY EPS BEARER CONTEXT ACCEPT message. In the extended protocol configuration options IE, the UE shall include the service-level-AA container with the length of two octets. In the service-level-AA container with the length of two octets, the UE shall:

a) include the service-level-AA payload parameter set to the service-level-AA payload received from the upper layers; and

b) set the service-level-AA payload type parameter to the type of the service-level-AA payload.

Upon receipt of the MODIFY EPS BEARER CONTEXT REQUEST message, if the SDNAEPC EAP message with the length of two octets is included in the Extended protocol configuration options IE, the UE supporting secondary DN authentication and authorization over EPC shall forward the SDNAEPC EAP message with the length of two octets to the upper layers.

Upon reception of an SDNAEPC EAP message with the length of two octets from the upper layers and if the UE has received an SDNAEPC EAP message with the length of two octets included in the Extended protocol configuration options IE of the MODIFY EPS BEARER CONTEXT REQUEST message from the network, the UE supporting secondary DN authentication and authorization over EPC shall include the Extended protocol configuration options IE in the MODIFY EPS BEARER CONTEXT ACCEPT message and include the SDNAEPC EAP message with the length of two octets in the Extended protocol configuration options IE.

The MODIFY EPS BEARER CONTEXT REQUEST message may include an extended protocol configuration options IE containing the ATSSS response with the length of two octets PCO parameter. If the UE receives an ATSSS response with the length of two octets PCO parameter in the extended protocol configuration options IE of the MODIFY EPS BEARER CONTEXT REQUEST message, the PDN connection associated with the EPS bearer context is established as a user-plane resource of an MA PDU session and the Measurement assistance information indicator is set to "Measurement assistance information length field and the measurement assistance information field included", the UE shall replace the stored Measurement assistance information with the received Measurement assistance information.

If the UE supports provisioning of ECS configuration information to the EEC in the UE, then upon receiving:

– at least one of ECS IPv4 address(es), ECS IPv6 address(es), ECS FQDN(s);

– at least one associated ECSP identifier; and

– optionally spatial validity conditions associated with the ECS address

in the Extended protocol configuration options IE of the MODIFY EPS BEARER CONTEXT REQUEST message, the UE shall pass them to the upper layers.

NOTE 2: The IP address(es) and/or FQDN(s) are associated with the ECSP identifier and replace previously provided ECS configuration information associated with the same ECSP identifier, if any.

Upon receipt of the MODIFY EPS BEARER CONTEXT ACCEPT message, the MME shall stop the timer T3486 and enter the state BEARER CONTEXT ACTIVE.

6.4.3.4 EPS bearer context modification not accepted by the UE

Upon receipt of the MODIFY EPS BEARER CONTEXT REQUEST message, the UE may reject the request from the MME by sending a MODIFY EPS BEARER CONTEXT REJECT message to the MME. The message shall include the EPS bearer identity and an ESM cause value indicating the reason for rejecting the EPS bearer context modification request.

The MODIFY EPS BEARER CONTEXT REJECT message contains an ESM cause that typically indicates one of the following ESM cause values:

#26: insufficient resources;

#41: semantic error in the TFT operation;

#42: syntactical error in the TFT operation;

#43: invalid EPS bearer identity;

#44: semantic error(s) in packet filter(s);

#45: syntactical error(s) in packet filter(s); or

#95 – 111: protocol errors.

The UE shall check the TFT in the request message for different types of TFT IE errors as follows:

a) Semantic errors in TFT operations:

1) TFT operation = "Create a new TFT" when there is already an existing TFT for the EPS bearer context.

2) When the TFT operation is an operation other than "Create a new TFT", the EPS bearer context being modified is the default EPS bearer content and there is no TFT for the default EPS bearer context.

3) TFT operation = "Delete packet filters from existing TFT" when it would render the TFT empty.

4) TFT operation = "Delete existing TFT" for a dedicated EPS bearer context.

In case 4 the UE shall reject the modification request with ESM cause #41 "semantic error in the TFT operation".

In the other cases the UE shall not diagnose an error and perform the following actions to resolve the inconsistency:

In case 1 the UE shall further process the new activation request to create a new TFT and, if it was processed successfully, delete the old TFT.

In case 2 the UE shall:

– process the new request and if the TFT operation is "Delete existing TFT" or "Delete packet filters from existing TFT", and if no error according to items b, c, and d was detected, consider the TFT as successfully deleted;

– process the new request as an activation request, if the TFT operation is "Add packet filters in existing TFT" or "Replace packet filters in existing TFT".

In case 3, if the packet filters belong to a dedicated EPS bearer context, the UE shall process the new deletion request and, if no error according to items b, c, and d was detected, the UE shall reject the modification request with ESM cause #41 "semantic error in the TFT operation".

In case 3, if the packet filters belong to the default EPS bearer context, the UE shall process the new deletion request and if no error according to items b, c, and d was detected then delete the existing TFT, this corresponds to using match-all packet filter for the default EPS bearer context.

b) Syntactical errors in TFT operations:

1) When the TFT operation = "Create a new TFT", "Add packet filters in existing TFT", "Replace packet filters in existing TFT" or "Delete packet filters from existing TFT" and the packet filter list in the TFT IE is empty.

2) TFT operation = "Delete existing TFT" or "No TFT operation" with a non-empty packet filter list in the TFT IE.

3) TFT operation = "Replace packet filters in existing TFT" when the packet filter to be replaced does not exist in the original TFT.

4) TFT operation = "Delete packet filters from existing TFT" when the packet filter to be deleted does not exist in the original TFT.

5) Void.

6) When there are other types of syntactical errors in the coding of the TFT IE, such as a mismatch between the number of packet filters subfield, and the number of packet filters in the packet filter list.

In case 3 the UE shall not diagnose an error, further process the replace request and, if no error according to items c and d was detected, include the packet filters received to the existing TFT.

In case 4 the UE shall not diagnose an error, further process the deletion request and, if no error according to items c and d was detected, consider the respective packet filter as successfully deleted.

Otherwise the UE shall reject the modification request with ESM cause #42 "syntactical error in the TFT operation".

c) Semantic errors in packet filters:

2) When the resulting TFT, which is assigned to a dedicated EPS bearer context, does not contain any packet filter applicable for the uplink direction among the packet filters created on request from the network.

The UE shall reject the modification request with ESM cause #44 "semantic errors in packet filter(s)".

d) Syntactical errors in packet filters:

1) When the TFT operation = "Create a new TFT", "Add packet filters to existing TFT", or "Replace packet filters in existing TFT" and two or more packet filters in the resultant TFT would have identical packet filter identifiers.

2) When the TFT operation = "Create a new TFT", "Add packet filters to existing TFT" or "Replace packet filters in existing TFT", and two or more packet filters among all TFTs associated with this PDN connection would have identical packet filter precedence values.

3) When there are other types of syntactical errors in the coding of packet filters, such as the use of a reserved value for a packet filter component identifier.

In case 1, if two or more packet filters with identical packet filter identifiers are contained in the new request, the UE shall reject the modification request with ESM cause #45 "syntactical errors in packet filter(s)". Otherwise, the UE shall not diagnose an error, further process the new request and, if it was processed successfully, delete the old packet filters which have the identical packet filter identifiers.

In case 2, if the old packet filters do not belong to the default EPS bearer context, the UE shall not diagnose an error, shall further process the new request and, if it was processed successfully, shall delete the old packet filters which have identical filter precedence values. Furthermore, the UE shall perform a UE requested bearer resource modification procedure to delete the packet filters in the network corresponding to the packet filters it has deleted on the UE side.

Otherwise the UE shall reject the modification request with ESM cause #45 "syntactical errors in packet filter(s)".

Upon receipt of the MODIFY EPS BEARER CONTEXT REJECT message with ESM cause value other than #43 "invalid EPS bearer identity" in state BEARER CONTEXT MODIFY PENDING, the MME shall stop the timer T3486, enter the state BEARER CONTEXT ACTIVE and abort the EPS bearer context modification procedure. If the network receives the MODIFY EPS BEARER CONTEXT REJECT message with ESM cause #43 "invalid EPS bearer identity", the MME locally deactivates the EPS bearer context(s) without peer-to-peer ESM signalling. When the MME detects that after the failed EPS bearer context modification there is a misalignment between the EPS bearer configuration and the EPS bearer context configuration or between the QoS on NAS and AS level, the MME should initiate the necessary procedures to achieve a re-alignment.

6.4.3.5 Abnormal cases in the UE

Apart from the case described in clause 6.3.3, the following abnormal cases can be identified:

a) Collision of UE requested bearer resource modification procedure and EPS bearer context modification procedure:

If the UE receives a MODIFY EPS BEARER CONTEXT REQUEST message during the UE requested bearer resource modification procedure, the Procedure transaction identity IE of the MODIFY EPS BEARER CONTEXT REQUEST message is set to "No procedure transaction identity assigned" and the EPS bearer indicated in the MODIFY EPS BEARER CONTEXT REQUEST message is the EPS bearer that the UE had requested to modify, the UE shall abort internally the UE requested bearer resource modification procedure, enter the state BEARER CONTEXT ACTIVE and proceed with the EPS bearer context modification procedure.

6.4.3.6 Abnormal cases on the network side

The following abnormal cases can be identified:

a) Expiry of timer T3486:

On the first expiry of the timer T3486, the MME shall resend the MODIFY EPS BEARER CONTEXT REQUEST and shall reset and restart timer T3486. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3486, the MME shall abort the procedure and enter the state BEARER CONTEXT ACTIVE.

The MME may continue to use the previous configuration of the EPS bearer context or initiate an EPS bearer context deactivation procedure.

b) Collision of UE requested PDN disconnect procedure and EPS bearer context modification:

When the MME receives a PDN DISCONNECT REQUEST message during an EPS bearer context modification procedure, and the EPS bearer to be modified belongs to the PDN connection the UE wants to disconnect, the MME shall terminate the EPS bearer context modification procedure locally, release any resources related to this procedure and proceed with the PDN disconnect procedure.

c) Collision of UE requested bearer resource modification procedure and EPS bearer context modification procedure:

If the MME receives a BEARER RESOURCE MODIFICATION REQUEST message during the EPS bearer context modification procedure and the EPS bearer indicated in the BEARER RESOURCE MODIFICATION REQUEST message is the EPS bearer that the network had requested to modify, the network shall ignore the BEARER RESOURCE MODIFICATION REQUEST message received in the state BEATER CONTEXT MODIFY PENDING. The network shall proceed with the EPS bearer modification procedure as if no BEARER RESOURCE MODIFICATION REQUEST message was received from the UE.

6.4.4 EPS bearer context deactivation procedure

6.4.4.1 General

The purpose of the EPS bearer context deactivation procedure is to deactivate an EPS bearer context or disconnect from a PDN by deactivating all EPS bearer contexts to the PDN. The EPS bearer context deactivation procedure is initiated by the network, and it may be triggered by the UE by means of the UE requested bearer resource modification procedure or UE requested PDN disconnect procedure.

In the case of EPS bearer context deactivation with reactivation requested for a PDN connection, if no NAS signalling connection exists, the MME follows the procedures for re-establishing the NAS signalling connection and deactivating the EPS bearer contexts to the PDN with reactivation requested, as specified in 3GPP TS 23.401 [10] clauses 5.4.4.1 and 5.10.3 and 3GPP TS 23.380 [33] clause 5.4.2.1.

If a UE is receiving emergency bearer services from a CSG cell, and the CSG subscription expires or is removed, the MME shall deactivate all non-emergency EPS bearers if any. The MME shall not deactivate the emergency EPS bearers.

If a detach is requested by the HSS for a UE that has bearers for emergency services, the MME shall send a DEACTIVATE EPS BEARER CONTEXT REQUEST message to the UE for all bearers that are not allocated for emergency services.

6.4.4.2 EPS bearer context deactivation initiated by the network

If a NAS signalling connection exists when the MME initiates the EPS bearer context deactivation procedure, the MME shall initiate the EPS bearer context deactivation procedure by sending a DEACTIVATE EPS BEARER CONTEXT REQUEST message to the UE, start the timer T3495, and enter the state BEARER CONTEXT INACTIVE PENDING (see example in figure 6.4.4.2.1). The DEACTIVATE EPS BEARER CONTEXT REQUEST message contains an ESM cause typically indicating one of the following:

#8: operator determined barring;

#26: insufficient resources;

#29: user authentication or authorization failed;

#36: regular deactivation;

#38: network failure;

#39: reactivation requested;

#112: APN restriction value incompatible with active EPS bearer context; or

#113: Multiple accesses to a PDN connection not allowed.

If the deactivation is triggered by a UE initiated bearer resource modification procedure or UE requested PDN disconnect procedure, the DEACTIVATE EPS BEARER CONTEXT REQUEST message shall contain the procedure transaction identity (PTI) value received by the MME in the BEARER RESOURCE MODIFICATION REQUEST or PDN DISCONNECT REQUEST respectively.

When the MME wants to deactivate all EPS bearer contexts of a PDN connection and thus disconnect the UE from the PDN, the MME shall include the EPS bearer identity of the default bearer associated to the PDN in the DEACTIVATE EPS BEARER CONTEXT REQUEST message. In this case, the MME shall not include the WLAN offload indication in the DEACTIVATE EPS BEARER CONTEXT REQUEST message, and if the UE receives the WLAN offload indication, the UE shall ignore the indication.

NOTE 1: If the DEACTIVATE EPS BEARER CONTEXT REQUEST message contains the UAS services not allowed indication in the extended protocol configuration options IE, then the ESM cause value #29 "user authentication or authorization failed" is included in the DEACTIVATE EPS BEARER CONTEXT REQUEST message.

If no NAS signalling connection exists when the MME initiates the EPS bearer context deactivation, the ESM entity in the MME shall locally deactivate the EPS bearer context towards the UE without any peer-to-peer ESM signalling between the MME and the UE.

NOTE 2: The EPS bearer context state(s) can be synchronized between the UE and the MME at the next EMM-IDLE to EMM-CONNECTED transition, e.g. during a service request or tracking area updating procedure.

Figure 6.4.4.2.1: EPS bearer context deactivation procedure

6.4.4.3 EPS bearer context deactivation accepted by the UE

Upon receipt of the DEACTIVATE EPS BEARER CONTEXT REQUEST message, the UE shall delete the EPS bearer context identified by the EPS bearer identity. After deactivating the identified EPS bearer context, the UE shall respond to the MME with the DEACTIVATE EPS BEARER CONTEXT ACCEPT.

If the EPS bearer identity indicated in the DEACTIVATE EPS BEARER CONTEXT REQUEST is that of the default bearer to a PDN, the UE shall delete all EPS bearer contexts associated to the PDN. After deactivating all EPS bearer contexts, the UE shall respond to the MME with the DEACTIVATE EPS BEARER CONTEXT ACCEPT.

Upon sending the DEACTIVATE EPS BEARER CONTEXT ACCEPT message, the UE shall enter the state BEARER CONTEXT INACTIVE. If due to the EPS bearer context deactivation only the PDN connection for emergency bearer services remains established, the UE shall consider itself attached for emergency bearer services only.

If the DEACTIVATE EPS BEARER CONTEXT REQUEST includes ESM cause #39 "reactivation requested" and the EPS bearer context is a default EPS bearer context, and the UE provided an APN for the establishment of the PDN connection, the UE shall stop timer T3396 if it is running for the APN provided by the UE. The UE should then re-initiate the UE requested PDN connectivity procedure for the same APN as the deactivated default EPS bearer context to reactivate the EPS bearer context. If the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall stop the timer T3396 associated with no APN if it is running, and should re-initiate the UE requested PDN connectivity procedure without including an APN. Additionally, the UE should re-initiate the request(s) for dedicated bearer resources that have been activated on request of the UE and released as a result of this EPS bearer context deactivation procedure. If the DEACTIVATE EPS BEARER CONTEXT REQUEST message was received for an emergency PDN connection, the UE shall not stop the timer T3396 associated with no APN if it is running. The UE should then re-initiate the UE requested PDN connectivity procedure for the emergency PDN connection.

NOTE 1: User interaction is necessary in some cases when the UE cannot re-activate the EPS bearer context(s) automatically.

NOTE 2: The UE behaviour is not specified for the case where the DEACTIVATE EPS BEARER CONTEXT REQUEST includes ESM cause #39 "reactivation requested" and the deactivated EPS bearer context was a dedicated EPS bearer context.

If the DEACTIVATE EPS BEARER CONTEXT REQUEST message contains a PTI value other than "no procedure transaction identity assigned" and "reserved" (see 3GPP TS 24.007 [12]), the UE uses the PTI to identify the UE requested bearer resource modification procedure or UE requested PDN disconnect procedure to which the EPS bearer context deactivation is related (see clause 6.5.4).

If the DEACTIVATE EPS BEARER CONTEXT REQUEST message contains a PTI value other than "no procedure transaction identity assigned" and "reserved" (see 3GPP TS 24.007 [12]), the UE shall release the traffic flow aggregate description associated to the PTI value provided.

If the ESM cause value is #26 "insufficient resources", the network may include a value for timer T3396 in the DEACTIVATE EPS BEARER CONTEXT REQUEST message. The UE shall take different actions depending on the timer value received for timer T3396 (if the UE is configured for dual priority, exceptions are specified in clause 6.5.5; if the UE is a UE configured to use AC11 – 15 in selected PLMN, exceptions are specified in clause 6.3.5):

i) if the timer value indicates neither zero nor deactivated, the UE shall stop timer T3396 associated with the corresponding APN, if it is running. The UE shall start timer T3396 with received value and not send another PDN CONNECTIVITY REQUEST, BEARER RESOURCE MODIFICATION REQUEST with exception of those identified in clause 6.5.4.1, or BEARER RESOURCE ALLOCATION REQUEST message for the same APN until timer T3396 expires or the timer T3396 is stopped. If the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall stop timer T3396 associated with no APN, if it is running. The UE shall start timer T3396 with the received value and not send another PDN CONNECTIVITY REQUEST message without an APN and with request type different from "emergency" and from "handover of emergency bearer services", or another BEARER RESOURCE MODIFICATION REQUEST with exception of those identified in clause 6.5.4.1, or BEARER RESOURCE ALLOCATION REQUEST message for a non-emergency PDN connection established without an APN provided by the UE, until timer T3396 expires or timer T3396 is stopped. The UE shall not stop timer T3396 upon a PLMN change or inter-system change;

ii) if the timer value indicates that this timer is deactivated, the UE shall not send another PDN CONNECTIVITY REQUEST, BEARER RESOURCE MODIFICATION REQUEST with exception of those identified in clause 6.5.4.1, or BEARER RESOURCE ALLOCATION REQUEST message for the same APN until the UE is switched off or the USIM is removed, or the UE receives an ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST, ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or MODIFY EPS BEARER CONTEXT REQUEST message for the same APN from the network or a DEACTIVATE EPS BEARER CONTEXT REQUEST message including ESM cause #39 "reactivation requested" for a default EPS bearer context for the same APN from the network. If the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall not send another PDN CONNECTIVITY REQUEST message without an APN and with request type different from "emergency" and from "handover of emergency bearer services", or another BEARER RESOURCE MODIFICATION REQUEST with exception of those identified in clause 6.5.4.1, or BEARER RESOURCE ALLOCATION REQUEST message for a non-emergency PDN connection established without APN provided by the UE , until the UE is switched off or the USIM is removed, or the UE receives an ACTIVATE DEFAULT EPS BEARER CONTEXT REQUEST, ACTIVATE DEDICATED EPS BEARER CONTEXT REQUEST or MODIFY EPS BEARER CONTEXT REQUEST message for a non-emergency PDN connection established without an APN provided by the UE, or a DEACTIVATE EPS BEARER CONTEXT REQUEST message including ESM cause #39 "reactivation requested" for a default EPS bearer context of a non-emergency PDN connection established without an APN provided by the UE. The timer T3396 remains deactivated upon a PLMN change or inter-system change; and

iii) if the timer value indicates zero, the UE:

– shall stop timer T3396 associated with the corresponding APN, if running, and may send another PDN CONNECTIVITY REQUEST, BEARER RESOURCE MODIFICATION REQUEST or BEARER RESOURCE ALLOCATION REQUEST message for the same APN; and

– if the UE did not provide an APN for the establishment of the PDN connection and the request type was different from "emergency" and from "handover of emergency bearer services", the UE shall stop timer T3396 associated with no APN, if running, and may send another PDN CONNECTIVITY REQUEST message without an APN, or another BEARER RESOURCE MODIFICATION REQUEST or BEARER RESOURCE ALLOCATION REQUEST message for a non-emergency PDN connection established without an APN provided by the UE.

If the timer T3396 is running when the UE enters state EMM-DEREGISTERED, the UE remains switched on, and the USIM in the UE remains the same, then timer T3396 is kept running until it expires or it is stopped.

If the UE is switched off when the timer T3396 is running, the UE shall behave as follows when the UE is switched on and the USIM in the UE remains the same:

– let t1 be the time remaining for T3396 timeout at switch off and let t be the time elapsed between switch off and switch on. If t1 is greater than t, then the timer shall be restarted with the value t1 – t. If t1 is equal to or less than t, then the timer need not be restarted. If the UE is not capable of determining t, then the UE shall restart the timer with the value t1;

– if prior to switch off, timer T3396 was running for a specific APN, because a PDN CONNECTIVITY REQUEST, BEARER RESOURCE MODIFICATION REQUEST or BEARER RESOURCE ALLOCATION REQUEST message containing the low priority indicator set to "MS is configured for NAS signalling low priority" was rejected with timer T3396, and if timer T3396 is restarted at switch on, then the UE configured for dual priority shall handle session management requests as indicated in clause 6.5.5; and

– if prior to switch off timer T3396 was running because a PDN CONNECTIVITY REQUEST without APN sent together with an ATTACH REQUEST message containing the low priority indicator set to "MS is configured for NAS signalling low priority" was rejected with timer T3396, and if timer T3396 is restarted at switch on, then the UE configured for dual priority shall handle session management requests as indicated in clause 6.5.5.

If the T3396 IE is not included, the UE shall proceed with deactivation procedure and then send DEACTIVATE EPS BEARER CONTEXT ACCEPT message.

Upon receipt of the DEACTIVATE EPS BEARER CONTEXT ACCEPT message, the MME shall enter the state BEARER CONTEXT INACTIVE and stop the timer T3495.

6.4.4.4 Abnormal cases in the UE

The following abnormal case can be identified:

a) UE is requested to deactivate a default EPS bearer context of the last PDN connection:

If EMM-REGISTERED without PDN connection is not supported by the UE or the MME, and the UE determines that the EPS bearer indicated in the DEACTIVATE EPS BEARER CONTEXT REQUEST message is the default EPS bearer of the last PDN connection that the UE has, then the UE shall respond by performing a detach procedure. Additionally, the UE should perform an attach procedure.

If EMM-REGISTERED without PDN connection is supported by the UE and the MME, the UE shall proceed with the deactivation procedure as specified in clause 6.4.4.3.

NOTE: User interaction is necessary in some cases when the UE cannot re-activate the EPS bearer(s), if any, automatically.

6.4.4.5 Abnormal cases on the network side

The following abnormal cases can be identified:

a) Expiry of timer T3495:

On the first expiry of the timer T3495, the MME shall resend the DEACTIVATE EPS BEARER CONTEXT REQUEST and shall reset and restart timer T3495. This retransmission is repeated four times, i.e. on the fifth expiry of timer T3495, the MME shall abort the procedure and deactivate the EPS bearer context locally without any peer-to-peer ESM signalling between the MME and the UE.

b) Collision of UE requested PDN disconnect procedure and EPS bearer context deactivation:

When the MME receives a PDN DISCONNECT REQUEST message during the EPS bearer context deactivation procedure, and the EPS bearer indicated in the DEACTIVATE EPS BEARER CONTEXT REQUEST message is a dedicated EPS bearer belonging to the PDN connection the UE wants to disconnect, the MME shall proceed with both procedures. If the EPS bearer indicated in the DEACTIVATE EPS BEARER CONTEXT REQUEST message is the default EPS bearer, the MME shall proceed with the EPS bearer context deactivation procedure.

6.4.4.6 Local EPS bearer context deactivation without NAS signalling

The UE and the MME deactivate EPS bearer contexts locally without peer-to-peer ESM signalling in the following cases:

1) during the service request procedure, if the E-UTRAN establishes the user plane radio bearers for one or more EPS bearer contexts but not for all the EPS bearer contexts, e.g. due to radio access control (see clause 5.6.1.4 for details);

1a) during the resume of NAS signalling connection procedure as specified in clause 5.3.1.3, if one or more but not all the suspended user plane radio bearers are resumed;

2) during the tracking area updating procedure but the network established the user plane radio bearers due to downlink pending data, if the E-UTRAN establishes the user plane radio bearers for one or more EPS bearer contexts but not for all the EPS bearer contexts indicated active by both UE and network;

NOTE 1: The synchronisation of the EPS bearers, for which the user plane radio bearers need to be established, indicated in EPS bearer context status information element in TRACKING AREA UPDATE ACCEPT message is not applicable in item 2.

3) during handover, if the target E-UTRAN does not establish all the user plane radio bearers for the UE;

4) if the E-UTRAN releases one or more user plane radio bearers but not all the user plane radio bearers of the UE due to E-UTRAN specific reasons; or

5) if triggered by an NBIFOM procedure (see 3GPP TS 24.161 [36]), for an NBIFOM multi-access PDN connection.

For cases 1) to 4), based on the indication from the lower layers, the UE and the MME shall locally deactivate the EPS bearer contexts for which no user plane radio bearers are set up.

NOTE 2: The above cases 1) to 4) do not apply for the UE when an RRC connection release occurs. The lower layers in the UE provide the user plane radio bearer context status to the ESM sublayer when a change in the user plane radio bearers is detected by the lower layers including establishment and release of user plane radio bearers for the UE in connected mode.

NOTE 3: The above cases 1) to 4) do not apply for the MME when the S1 release procedure occurs as specified in 3GPP TS 23.401 [10]).

If due to any of the cases described above the UE locally deactivates a default EPS bearer context, the UE shall locally deactivate all EPS bearer contexts associated to the PDN connection with the default EPS bearer context.

If the UE locally deactivates the EPS bearer context(s) of the last remaining PDN connection, and EMM-REGISTERED without PDN connection is not supported by the UE or the MME, the UE shall perform a local detach and enter state EMM-DEREGISTERED. If this occurs during a service request procedure for CS fallback, the UE shall reselect to GERAN or UTRAN and continue with the CS service, otherwise the UE shall initiate an attach procedure.

If the UE locally deactivates the EPS bearer context(s) of the last remaining PDN connection, and EMM-REGISTERED without PDN connection is supported by the UE and the MME, the UE shall enter state EMM-REGISTERED.

If the UE locally deactivates the EPS bearer context(s) of the last remaining PDN connection for non-emergency bearer services and only the PDN connection for emergency bearer services remains established, the UE shall consider itself attached for emergency bearer services only.

The MME shall deactivate the GBR EPS bearer contexts locally without peer-to-peer ESM signalling, when the MME performs locally the release of the S1AP signalling connection due to the S1AP signalling connection is lost. All non-GBR EPS bearers established are preserved in the MME and in the PDN GW.

If the E‑UTRAN requests the MME to release the S1AP signalling connection, the MME shall deactivate or preserve the GBR EPS bearer contexts according to 3GPP TS 23.401 [10], clause 5.3.5. All non-GBR EPS bearer contexts established are preserved in the MME and in the PDN GW.

NOTE 4: The UE and the MME will synchronize the EPS bearer contexts subsequently during the next service request procedure, tracking area updating procedure or routing area updating procedure.

If due to any of the cases described above the MME locally deactivates a default EPS bearer context, the MME shall locally deactivate all EPS bearer contexts associated to the PDN connection with the default EPS bearer context without peer-to-peer ESM signalling to the UE.

If the MME locally deactivates the EPS bearer context(s) of the last remaining PDN connection, and EMM-REGISTERED without PDN connection is not supported by the UE or the MME, the MME shall perform a local detach and enter state EMM-DEREGISTERED.

If the MME locally deactivates the EPS bearer context(s) of the last remaining PDN connection, and EMM-REGISTERED without PDN connection is supported by the UE and the MME, the MME shall enter state EMM-REGISTERED.

For EPS bearer context deactivation procedure initiated by the network, if no NAS signalling connection exists, the MME locally deactivates the EPS bearer context(s) without peer-to-peer ESM signalling In the case of reactivation requested, the MME can perform this local deactivation only when the EMM-entity in the network was unable to re-establish the NAS signalling connection. The EPS bearer context deactivation procedure is not initiated by the network when the MME disconnects the UE from the last remaining PDN to which it is connected and EMM-REGISTERED without PDN connection is not supported by the UE or the MME. In this case, the MME initiates a network initiated detach procedure.

If the MME locally deactivates the EPS bearer context(s) of the last remaining PDN connection for non-emergency bearer services and only the PDN connection for emergency bearer services remains established for the UE, the MME shall consider the UE to be attached for emergency bearer services only.