Content for  TS 23.401  Word version:  19.0.0

The UE initiates the UE Requested PDN procedure by the transmission of a PDN Connectivity Request (APN, PDN Type, Protocol Configuration Options, Request Type, Header Compression Configuration) message. If the UE was in ECM-IDLE mode, this NAS message is preceded by the Service Request procedure if any of the exiting PDN connections were using the User Plane without CIoT EPS Optimisation, or, if the user plane was used just with User Plane CIoT EPS Optimisations, a Connection Resume Procedure is executed instead. PDN type indicates the requested IP version (IPv4, IPv4v6, IPv6, Non-IP, Ethernet). The MME verifies that the APN provided by UE is allowed by subscription. If the APN provided by the UE is not allowed by subscription, based on operator policy, the MME may reject the request from the UE with an appropriate cause, or accept the request by replacing the UE requested APN with a network supported APN. The MME uses that network supported APN for the remainder of this procedure, except that the MME provides to the UE the same APN that the UE requested. If the UE did not provide an APN, the MME shall use the APN from the default PDN subscription context, and, use this APN for the remainder of this procedure. Protocol Configuration Options (PCO) are used to transfer parameters between the UE and the Network and are sent transparently through the MME and the Serving-GW. The Protocol Configuration Options may include the Address Allocation Preference, which indicates that the UE prefers to obtain an IPv4 address only after the default bearer activation by means of DHCPv4. If the UE has UTRAN or GERAN capabilities, it shall send the NRSU in the PCO to indicate the support of the network requested bearer control in UTRAN/GERAN. The UE sends the ETFTU in the PCO to indicate the support of the extended TFT filter format. The Request Type indicates "initial request" if the UE requests new additional PDN connectivity over the 3GPP access network for multiple PDN connections, the Request Type indicates "handover" when the UE is performing a handover from non-3GPP access and the UE has already established connectivity with the PDN over the non-3GPP access. The UE shall indicate Request Type "Emergency" when it requests a PDN connection for emergency services. If the message is being sent via a HeNB which has a collocated L-GW, it includes the L-GW address in the Uplink NAS transport message to the MME. If a UE indicated Control Plane CIoT EPS Optimisation supported in Preferred Network Behaviour and supports header compression, it shall include the Header Compression Configuration, unless "Non-IP" or "Ethernet" PDN type is indicated. The Header Compression Configuration includes the information necessary for the ROHC channel setup. Optionally, the Header Compression Configuration may also include additional header compression context setup parameters, if the UE already has the application traffic information, e.g. the target server IP address. The UE shall include in the PCO the 3GPP PS Data Off UE Status, which indicates whether the user has activated or deactivated 3GPP PS Data Off. In the case of satellite access for Cellular IoT, the MME may verify the UE location as described in clause 4.13.4.

If the MME receives a PDN Connectivity Request from an emergency attached or RLOS attached UE or the PDN Connectivity Request is for normal services and the mobility or access restrictions do not allow the UE to access normal services the MME shall reject this request. If the Request Type indicates "Emergency" and the MME is not configured to support PDN connections for emergency services the MME shall reject the PDN Connectivity Request with an appropriate reject cause. If the Request Type is not set to "Emergency", and the UE has indicated support for Attach without PDN Connectivity, and the network supports Attach without PDN Connectivity, and the PDN Connection Restriction is set in the subscriber data, then the MME should reject the PDN Connectivity Request with an appropriate cause value. If the Request Type indicates "Emergency", the MME derives a PDN-GW from the MME Emergency Configuration Data or the MME selects a PDN-GW as described in clause 4.3.12.4 on PDN-GW Selection Function (3GPP accesses) according to the Emergency APN in the MME Emergency Configuration Data. This selection shall provide a PDN-GW from visited PLMN only. If the Request Type indicates "Emergency" and the MME is configured to support PDN connections for emergency services, it uses the MME Emergency Configuration Data for the bearer establishment in this step and ignores any subscription data limitation. If the Request Type indicates "Handover", the MME uses the PDN-GW stored in the Subscription Data retrieved by the MME during the Update Location performed at attach. If the Request Type indicates "initial request" the MME selects a PDN-GW as described in clause 4.3.8.1 on PDN-GW Selection Function (3GPP accesses). If the UE provided APN is authorized for LIPA according to the user subscription, the MME shall use the CSG Subscription Data to authorize the connection. If the subscription context does not indicate that the APN is for a PDN connection to an SCEF the MME allocates a Bearer Id, and sends a Create Session Request (IMSI, MSISDN, MME TEID for control plane, RAT type, LTE-M RAT type reporting to PGW flag, PDN-GW address, PDN Address, Default EPS Bearer QoS, PDN Type, subscribed APN-AMBR, APN, EPS Bearer Id, Protocol Configuration Options, Handover Indication, ME Identity, User Location Information (ECGI and TAI), UE Time Zone, User CSG Information, MS Info Change Reporting support indication, Selection Mode, Charging Characteristics, Trace Reference, Trace Type, Trigger Id, OMC Identity, Maximum APN Restriction, Dual Address Bearer Flag) message to the Serving-GW. If Control Plane CIoT EPS Optimisation applies, then the MME shall also indicate S11-U tunnelling of NAS user data and send its own S11-U IP address and MME DL TEID for DL data forwarding by the SGW. If the MME determines the PDN connection shall only use the Control Plane CIoT EPS Optimisation, the MME shall include a Control Plane Only PDN Connection Indicator in Create Session Request. For PDN type "non-IP", if the APN subscription data indicate a SCEF connection needs to be used, then the MME allocates an EPS Bearer Identity for the Default Bearer associated with the UE and established connection to the SCEF address indicated in subscription data according to TS 23.682 and the steps 2,3,4,5,6 are not executed. The rest of the interactions with the UE apply as specified below. The RAT type is provided in this message for the later PCC decision. The RAT type shall enable NB-IoT, LTE-M and WB-E-UTRAN to be differentiated by the PDN-GW The MSISDN is included if the MME has it stored for that UE. Handover Indication is included if the Request Type indicates "handover". Selection Mode indicates whether a subscribed APN was selected, or a non-subscribed APN sent by the UE was selected. The P-GW may use Selection Mode when deciding whether to accept or reject the default bearer activation. For example, if an APN requires subscription, the P-GW is configured to accept only the default bearer activation that requests a subscribed APN as indicated by Selection Mode. Charging Characteristics indicates which kind of charging the bearer context is liable for. The charging characteristics for the PS subscription and individually subscribed APNs as well as the way of handling Charging Characteristics and whether to send them or not to the P-GW is defined in TS 32.251. The MME shall include Trace Reference, Trace Type, Trigger Id, and OMC Identity if S-GW and/or P-GW trace is activated. The MME shall copy Trace Reference, Trace Type, and OMC Identity from the trace information received from the HLR or OMC. The Maximum APN Restriction denotes the most stringent restriction as required by any already active bearer context. If there are no already active bearer contexts, this value is set to the least restrictive type (see clause 15.4 of TS 23.060). If the P-GW receives the Maximum APN Restriction, then the P-GW shall check if the Maximum APN Restriction value does not conflict with the APN Restriction value associated with this bearer context request. If there is no conflict the request shall be allowed, otherwise the request shall be rejected with sending an appropriate error cause to the UE. If the PDN subscription context contains a subscribed IPv4 address and/or IPv6 prefix, the MME indicates it in the PDN address. The MME may change the requested PDN type according to the subscription data for this APN as described in clause 5.3.1.1. The MME shall set the Dual Address Bearer Flag when the PDN type is set to IPv4v6 and all SGSNs which the UE may be handed over to are Release 8 or above supporting dual addressing, which is determined based on node pre-configuration by the operator. If there is an APN Rate Control Status in the MME MM Context for the UE, the MME forwards it to the SGW. Based on UE and Serving-GW capability of supporting MT-EDT, Communication Pattern parameters or local policy, the MME may indicate to Serving-GW that MT-EDT is applicable for the PDN Connection.

The Serving-GW creates a new entry in its EPS Bearer table and sends a Create Session Request (IMSI, MSISDN, Serving-GW Address for the user plane, Serving-GW TEID of the user plane, Serving-GW TEID of the control plane, RAT type, Default EPS Bearer QoS, PDN Type, PDN Address, subscribed APN-AMBR, APN, Bearer Id, Protocol Configuration Options, Handover Indication, ME Identity, User Location Information (ECGI), UE Time Zone, User CSG Information, MS Info Change Reporting support indication, PDN Charging Pause Support indication, Selection Mode, Charging Characteristics, Trace Reference, Trace Type, Trigger Id, OMC Identity, Maximum APN Restriction, Dual Address Bearer Flag, APN Rate Control Status) message to the PDN-GW indicated in the PDN-GW address received in the previous step. After this step, the Serving-GW buffers any downlink packets it may receive from the PDN-GW until receives the message in step 13 below. The MSISDN is included if received from the MME. If the Handover Indication is included, the Serving-GW includes it in the Create Session Request message. If the Serving-GW has received the Control Plane Only PDN Connection Indicator in step 2, the Serving-GW informs the PDN-GW this information in Create Session Request. The Serving-GW and PDN-GW shall indicate the use of CP only on their CDRs. P-GWs shall not perform any checks of Maximum APN Restriction if Create Default Bearer Request includes emergency APN. If the PDN-GW detects that the 3GPP PS Data Off UE Status has changed, the PDN-GW shall indicate this event to the charging system for offline and online charging.

If dynamic PCC is deployed and the Handover Indication is not present, the PDN-GW may employ an IP-CAN Session Establishment procedure as defined in TS 23.203 with the PCRF to get the default PCC rules for the UE. This may lead to the establishment of a number of dedicated bearers following the procedures defined in clause 5.4.1 in association with the establishment of the default bearer which is described in Annex F. The RAT type is provided to the PCRF by the PDN-GW if received by the previous message. If the PDN-GW/PCEF is configured to activate predefined PCC rules for the default bearer, the interaction with the PCRF is not required (e.g. operator may configure to do this) at the moment. The ETFTU is provided to the PCRF by the PDN-GW, if received in the PCO from the UE and the PDN-GW supports the extended TFT filter format. If the PCRF decides that the PDN connection may use extended TFT filters, it shall return the ETFTN indicator to the PDN-GW for inclusion in the protocol Configuration Options returned to the UE. The PCRF may modify the APN-AMBR and the QoS parameters (QCI and ARP) associated with the default bearer in the response to the PDN-GW as defined in TS 23.203. If the PCC is configured to support emergency services and dynamic PCC is deployed, the PCRF, based on the Emergency APN, sets the ARP of the PCC rules to a value that is reserved for emergency services and the authorization of dynamic PCC rules as described in TS 23.203. If dynamic PCC is not deployed, the PDN-GW is configured to set the ARP to a value that is reserved for emergency services. If dynamic PCC is deployed and the Handover Indication is present, the PDN-GW executes a PCEF-Initiated IP-CAN Session Modification procedure with the PCRF as specified in TS 23.203 to report the new IP-CAN type. Depending on the active PCC rules, the establishment of dedicated bearer for the UE may be required. The establishment of those bearers shall take place in combination with the default bearer activation as described in Annex F. This procedure can continue without waiting for a PCRF response. If changes to the active PCC rules are required, the PCRF may provide them after the handover procedure is finished. In both cases (Handover Indication is present or not), if dynamic PCC is not deployed, the PDN-GW may apply local QoS policy. This may lead to the establishment of a number of dedicated bearers for the UE following the procedures defined in clause 5.4.1 in combination with the establishment of the default bearer, which is described in Annex F. If the CSG information reporting triggers are received from the PCRF, the PDN-GW should set the CSG Information Reporting Action IE accordingly. If 3GPP PS Data Off status is received in the PCO from the UE and PDN-GW supports 3GPP PS Data Off, the PDN-GW shall provide the 3GPP PS Data Off status to the PCRF. If the PCRF supports 3GPP PS Data Off, it shall return 3GPP PS Data Off support to the PDN-GW for inclusion in the PCO returned to the UE. If the 3GPP PS Data Off UE Status indicates that 3GPP PS Data Off is activated for the UE, the PDN-GW shall enforce the PCC rules for downlink traffic to be used when 3GPP PS Data Off is activated. If received, the PDN-GW may take the APN Rate Control Status into account when encoding the APN Rate Control parameters in Protocol Configuration Options and when enforcing the APN Rate Control as described in clause 4.7.7.3.

The P-GW creates a new entry in its EPS bearer context table and generates a Charging Id for the Default Bearer. The new entry allows the P-GW to route user plane PDUs between the S-GW and the packet data network, and to start charging. The way the P-GW handles Charging Characteristics that it may have received is defined in TS 32.251. The PDN-GW returns a Create Session Response (PDN-GW Address for the user plane, PDN-GW TEID of the user plane, PDN-GW TEID of the control plane, PDN Type, PDN Address, EPS Bearer Id, EPS Bearer QoS, Protocol Configuration Options, Charging Id, Prohibit Payload Compression, APN Restriction, Cause, MS Info Change Reporting Action (Start) (if the PDN-GW decides to receive UE's location information during the session), CSG Information Reporting Action (Start) (if the PDN-GW decides to receive UE's User CSG information during the session), Presence Reporting Area Action (if the PDN-GW decides to receive notifications about a change of UE presence in Presence Reporting Area), PDN Charging Pause Enabled indication (if PDN-GW has chosen to enable the function), APN-AMBR, Delay Tolerant Connection) message to the Serving-GW. The PDN-GW takes into account the received PDN type, the Dual Address Bearer Flag and the policies of operator when the PDN-GW selects the PDN type to be used as follows. If the received PDN type is IPv4v6 and both IPv4 and IPv6 addressing are possible in the PDN but the Dual Address Bearer Flag is not set, or only single IP version addressing for this APN is possible in the PDN, the PDN-GW selects a single IP version (either IPv4 or IPv6). If the received PDN type is IPv4 or IPv6, the PDN-GW uses the PDN type if it is supported in the PDN, otherwise an appropriate error cause will be returned. The PDN-GW allocates a PDN Address according to the selected PDN Type If the PDN-GW has selected a PDN type different from the received PDN Type, the PDN-GW indicates together with the PDN type IE a reason cause to the UE why the PDN type has been modified, as described in clause 5.3.1.1. PDN Address may contain an IPv4 address for IPv4 and/or an IPv6 prefix and an Interface Identifier. If the PDN has been configured by the operator so that the PDN addresses for the requested APN shall be allocated by usage of DHCPv4 only, or if the PDN-GW allows the UE to use DHCPv4 for address allocation according to the Address Allocation Preference received from the UE, the PDN Address shall be set to 0.0.0.0, indicating that the IPv4 address shall be negotiated by the UE with after completion of the Default Bearer Activation procedure. For external PDN addressing for IPv6, the PDN-GW obtains the IPv6 prefix from the external PDN using either RADIUS or Diameter client function. In the PDN Address field of the Create Session Response, the PDN-GW includes the Interface Identifier and IPv6 prefix. The PDN-GW sends Router Advertisement to the UE after default bearer establishment with the IPv6 prefix information for all cases. If the PDN address is contained in the Create Session Request, the PDN-GW shall allocate the IPv4 address and/or IP6 prefix contained in the PDN address to the UE. If Handover Indication indicates "Handover", the PDN Address Information shall contain the same IP address the UE obtained during PDN connectivity establishment over the non-3GPP access. The PDN-GW derives the BCM based on the NRSU and operator policy. The PDN-GW derives whether the extended TFT filter format is to be used based on the ETFTU, ETFTN received from the PCRF and operator policy. Protocol Configuration Options contains the BCM, ETFTN as well as optional PDN parameters that the P-GW may transfer to the UE. These optional PDN parameters may be requested by the UE, or may be sent unsolicited by the P-GW. Protocol Configuration Options are sent transparently through the MME. If the PDN type is Non-IP or Ethernet, the PDN-GW uses the APN and IMSI to determine what local actions to perform before answering the Serving-GW. The PDN-GW includes a Delay Tolerant Connection indication if the PDN-GW supports receiving a rejection cause from the SGW indicating that the UE is temporarily not reachable due to power saving, and holding mobile terminated procedures until the PDN-GW receives a message indicating that the UE is available for end to end signalling. When the Handover Indication is present, the PDN-GW does not yet send downlink packets to the S-GW; the downlink path is to be switched at step 13a. If the PDN-GW is an L-GW, it does not forward downlink packets to the S-GW. The packets will only be forwarded to the HeNB at step 10 via the direct user plane path for Local IP Access. If the 3GPP PS Data Off UE Status was present in the Create Session Request PCO, and if the network supports 3GPP PS Data Off, the PDN-GW shall include the 3GPP PS Data Off Support Indication in the Create Session Response PCO.

The Serving-GW returns a Create Session Response (PDN Type, PDN Address, Serving-GW address for User Plane, Serving-GW TEID for User Plane, Serving-GW TEID for control plane, EPS Bearer Id, EPS Bearer QoS, PDN-GW address and TEID (GTP-based S5/S8) or GRE key (PMIP-based S5/S8) at the PDN-GW for uplink traffic, Protocol Configuration Options, Prohibit Payload Compression, APN Restriction, Cause, MS Info Change Reporting Action (Start), CSG Information Reporting Action (Start), Presence Reporting Area Action, APN-AMBR, DTC) message to the MME. The DL TFT for PMIP-based S5/S8 is obtained from interaction between the Serving-GW and the PCRF as described in clause 5.6.1 of TS 23.402, when PCC is deployed; otherwise, the DL TFT IE is wildcarded, matching any downlink traffic. If the UE indicates the Request Type as "Handover", this message also serves as an indication to the MME that the S5/S8 bearer setup and update has been successful. At this step the GTP tunnel(s) over S5/S8 are established If Control Plane CIoT EPS Optimisation applies, and if MME doesn't include Control Plane Only PDN Connection Indicator in the Create Session Request:

• If separation of S11-U from S1-U is required, the Serving-GW shall include the Serving-GW IP address and TEID for S11-U and additionally the Serving-GW IP address and TEID for S1-U in the Create Session Response.
• Otherwise if separation of S11-U from S1-U is not required, the Serving-GW includes the Serving-GW IP address and TEID for S11-U in Create Session Response.

If an APN Restriction is received, then the MME shall store this value for the Bearer Context and the MME shall check this received value with the stored value for the Maximum APN Restriction to ensure there are no conflicts between values. If the consequence of this check results in the PDN connectivity being rejected, the MME shall initiate a Bearer Deactivation and return an appropriate error cause. If the PDN Connectivity Request is accepted, the MME shall determine a (new) value for the Maximum APN Restriction. If there is no previously stored value for Maximum APN Restriction, then the Maximum APN Restriction shall be set to the value of the received APN Restriction. The P-GW shall ignore Maximum APN restriction if the request includes the Emergency APN. For emergency service MME shall not deactivate bearer(s), if present, to maintain valid APN restriction combination. If the MS Info Change Reporting Action (Start) and/or the CSG Information Reporting Action (Start) are received for this bearer context, then the MME shall store this for the bearer context and the MME shall report to that P-GW via the S-GW whenever a UE's Location Information and/or User CSG Information change occurs that meets the P-GW request, as described in clause 15.1.1a of TS 23.060. If Presence Reporting Area Action is received for this bearer context, the MME shall store this information for the bearer context and shall report to that P-GW via the S-GW whenever a change of UE presence in a Presence Reporting Area is detected, as described in clause 5.9.2.2. The MME may need to modify the UE-AMBR, which has been assigned to the eNodeB, based on the subscribed UE-AMBR and the updated set of APN-AMBRs in use. The principles to determine the UE-AMBR are described in clause 4.7.3. The MME sends PDN Connectivity Accept Session Management Request (APN, PDN Type, PDN Address, EPS Bearer Id, Protocol Configuration Options, Header Compression Configuration, Control Plane Only Indicator) message to the UE. If the PDN connection uses the user plane over the radio, this message is contained in an S1_MME control message Bearer Setup Request (EPS Bearer QoS, UE-AMBR, PDN Connectivity Accept, S1-TEID) to the eNodeB. However, if Control Plane CIoT EPS Optimisation applies to the PDN connection, an S1-AP Downlink NAS transport message is used. The S1-AP Initial Context Setup Request message includes the TEID at the Serving-GW used for user plane and the address of the Serving-GW for user plane. If the PDN type is set to "Non-IP" the MME includes it in the S1-AP Initial Context Setup Request so that the eNodeB disables header compression. If the PDN type is set to "Ethernet" the MME includes it in the S1-AP Initial Context Setup Request so that any eNodeB header compression functionality can act appropriately. In addition, if the PDN connection is established for Local IP Access, the corresponding S1 Initial Context Setup Request message includes a Correlation ID for enabling the direct user plane path between the HeNB and the L-GW. If the PDN connection is established for SIPTO at the Local Network with L-GW function collocated with the (H)eNB, the corresponding S1-AP Initial Context Setup Request includes a SIPTO Correlation ID for enabling the direct user plane path between the (H)eNB and the L-GW. LIPA and SIPTO do not apply to Control Plane CIoT EPS Optimisation. In the PDN Connectivity Accept message, the MME does not include the IPv6 prefix within the PDN Address. The MME includes the APN-AMBR and the EPS Bearer QoS parameter QCI into the Session Management Request. Furthermore, if the UE has UTRAN or GERAN capabilities and the network supports mobility to UTRAN or GERAN, the MME uses the EPS bearer QoS parameters to derive the corresponding PDP context parameters QoS Negotiated (R99 QoS profile), Radio Priority, Packet Flow Id and TI and includes them in the Session Management Request. If the UE indicated in the UE Network Capability that it does not support BSS packet flow procedures, then the MME shall not include the Packet Flow Id. MME will not send the S1 Bearer Setup Request message until any outstanding S1 Bearer Setup Response message for the same UE has been received or timed out. If the APN-AMBR has changed the MME may update the UE-AMBR if appropriate. The MME may include an indication whether the traffic of this PDN Connection is allowed to be offloaded to WLAN, as described in clause 4.3.23. If the UE has indicated PDN type "Non-IP" or "Ethernet", the MME and PDN-GW shall not change PDN type. If the MME or PDN-GW has changed the PDN Type, an appropriate reason cause shall be returned to the UE as described in clause 5.3.1.1. If Control Plane CIoT EPS Optimisation applies for an IP PDN connection, and the UE has sent in the PDN Connectivity Request the Header Compression Configuration, the MME shall include the Header Compression Configuration in the PDN Connectivity Accept message. The MME also binds the uplink and downlink ROHC channels to support header compression feedback signalling. If the UE has included ROHC context setup parameters in Header Compression Configuration in the PDN Connectivity Request, the MME may acknowledge ROHC context setup parameters. If the ROHC context is not established during the PDN connection establishment procedure, before using the compressed format for sending the data, the UE and the MME need to establish the ROHC context with ROHC IR packet based on Header Compression Configuration. If the MME based on local policy determines the PDN connection shall only use the Control Plane CIoT EPS Optimisation, the MME shall include a Control Plane Only Indicator in the Session Management Request. For PDN connections with an SCEF, the MME shall always include the Control Plane Only Indicator. If there is an existing SGi PDN connection for this UE for which the MME included a Control Plane Only Indicator, the MME shall include it also for the additional SGi PDN connection. If the MME did not include a Control Plane Only Indicator for any of the existing SGi PDN connections of this UE, the MME shall not include it for the additional SGi PDN connection. A UE receiving the Control Plane Only Indicator, for a PDN connection shall only use the Control Plane CIoT EPS Optimisation for this PDN connection.

If the eNodeB received an S1-AP Initial Context Setup Request, the eNodeB sends RRC Connection Reconfiguration to the UE including the PDN Connectivity Accept message. If the eNodeB received an S1-AP Downlink NAS Transport message containing the NAS PDN Connectivity Accept message, the eNode B sends a RRC Direct Transfer message to the UE and the steps 9 and 10 are not executed. The UE shall store the QoS Negotiated, Radio Priority, Packet Flow Id and TI, which it received in the Session Management Request IE, for use when accessing via GERAN or UTRAN. The UE may provide EPS Bearer QoS parameters to the application handling the traffic flow. The application usage of the EPS Bearer QoS is implementation dependent. The UE shall not reject the RRC Connection Reconfiguration on the basis of the EPS Bearer QoS parameters contained in the Session Management Request. If the UE receives an IPv4 address set to 0.0.0.0, it may negotiate the IPv4 address with DHCPv4 as specified in TS 29.061, If the UE receives an IPv6 interface identifier, it may wait for the Router Advertisement from the network with the IPv6 prefix information or it may send a Router Solicitation if necessary.

The UE sends the RRC Connection Reconfiguration Complete to the eNodeB.

The eNodeB send an S1-AP Bearer Setup Response to the MME. The S1-AP message includes the TEID of the eNodeB and the address of the eNodeB used for downlink traffic on the S1_U reference point. If the Correlation ID or SIPTO Correlation ID is included in the Bearer Setup Request, the eNodeB shall use the included information to establish a direct user plane path to the L-GW and forward uplink data for Local IP Access or SIPTO at the Local Network with L-GW function collocated with the (H)eNB accordingly.

The UE NAS layer builds a PDN Connectivity Complete message including EPS Bearer Identity. The UE then sends a Direct Transfer (PDN Connectivity Complete) message to the eNodeB.

The eNodeB sends an Uplink NAS Transport (PDN Connectivity Complete) message to the MME. After the PDN Connectivity Accept message and once the UE (if applicable to the PDN type) has obtained a PDN Address Information, the UE can then send uplink packets towards the eNodeB which may then be tunnelled by the MME to the Serving-GW and PDN-GW, or transferred by the MME to an SCEF (see TS 23.682), as per subscription information related to APN discussed above in step 2. If the UE requested for a dual address PDN type (IPv4v6) to a given APN and was granted a single address PDN type (IPv4 or IPv6) by the network with a reason cause indicating that only single IP version per PDN connection is allowed, the UE should request for the activation of a parallel PDN connection to the same APN with a single address PDN type (IPv4 or IPv6) other than the one already activated. If the UE receives no reason cause in step 8 in response to a IPv4v6 PDN type and it receives an IPv6 Interface Identifier apart from the IPv4 address or 0.0.0.0 in the PDN Address field, it considers that the request for a dual address PDN was successful. It can wait for the Router Advertisement from the network with the IPv6 prefix information or it may send Router Solicitation if necessary.

Upon reception of the Bearer Setup Response message in step 10 and the PDN Connectivity Complete message in step 12, the MME sends a Modify Bearer Request (EPS Bearer Identity, eNodeB address, eNodeB TEID, Handover Indication, Presence Reporting Area Information) message to the Serving-GW. If the Control Plane CIoT EPS Optimisation applies and the PDN connection is not served via a SCEF type of connectivity, steps 13 and 14 are executed only if the MME needs to report a change of UE presence in Presence Reporting Area, otherwise, if the PDN connection is served by SCEF, steps 13,14, 15, and 16 are not executed. If Request Type indicates "handover", the Handover Indication is also included. If the MME has been requested to report a change of UE presence in Presence Reporting Area, the MME includes in this message the Presence Reporting Area Information comprising the PRA identifier(s) and indication(s) on whether the UE is inside or outside the area(s). When receiving the request for reporting change of UE presence in Presence Reporting Area, and the MME decides not to activate reporting UE presence in one or more of the received Presence Reporting Area(s), the MME reports also the inactive Presence Reporting Area(s) in this message.

If the Handover Indication is included in step 13, the Serving-GW sends a Modify Bearer Request (Handover Indication) message to the PDN-GW to prompt the PDN-GW to tunnel packets from non 3GPP IP access to 3GPP access system and immediately start routing packets to the Serving-GW for the default and any dedicated EPS bearers established. If Presence Reporting Area Information is included in step 13, the Serving-GW sends a Modify Bearer Request (Presence Reporting Area Information) message to the PDN-GW.

The PDN-GW acknowledges by sending Modify Bearer Response to the Serving-GW.

The Serving-GW acknowledges by sending Modify Bearer Response (EPS Bearer Identity) to the MME. The Serving-GW can then send its buffered downlink packets.

After the MME receives Modify Bearer Response in step 14, if Request type does not indicate handover and an EPS bearer was established and if the subscription data indicates that the user is allowed to perform handover to non-3GPP accesses and if this is the first PDN connection associated with this APN and if the MME selected a PDN-GW that is different from the PDN-GW identity which was previously indicated by the HSS in the PDN subscription context, the MME shall send a Notify Request including the PDN-GW address and the APN to the HSS for mobility with non-3GPP accesses. The message shall include information that identifies the PLMN in which the PDN-GW is located. For an unauthenticated or roaming UE, if the Request Type of the UE requested connectivity procedure indicates "Emergency", the MME shall not send any Notify Request to the HSS. For a non-roaming authenticated UE, based on operator configuration (e.g. on whether Voice over WLAN is supported or not by the operator), if the Request Type indicates "Emergency", the MME may send a Notify Request to the HSS including the "PDN-GW currently in use for emergency services", which comprises the PDN-GW address and an indication that the PDN connection is for emergency services. The HSS shall store it as part of the UE context for emergency services.

In the case of non-emergency services, the HSS stores the PDN-GW identity and the associated APN. In the case of emergency services, the HSS stores the "PDN-GW currently in use for emergency services". Then the HSS sends a Notify Response to the MME.

The procedure is triggered by either step 1a or step 1b.

The UE initiates the UE requested PDN disconnection procedure by the transmission of a PDN Disconnection Request (LBI) message. The LBI indicates the default bearer associated with the PDN connection being disconnected. If the UE was in ECM-IDLE mode, this NAS message is preceded by the Service Request procedure if any of the exiting PDN connections were using the User Plane without CIoT EPS Optimisation, or, if the user plane was used just with User Plane CIoT EPS Optimisations, a Resume Procedure is executed instead.

The MME decides to release the PDN connection. This may be e.g. due to change of subscription, lack of resources, due to SIPTO if the PDN connection serves a SIPTO-allowed APN or on receiving a PDN-GW Restart Notification from the Serving-GW as specified in TS 23.007. If the UE is in ECM-IDLE state and the reason for releasing PDN connection is "reactivation requested" e.g. due to SIPTO, the MME initiates paging via Network Triggered Service Request procedure in clause 5.3.4.3 from step 3a onwards in order to inform UE of the request.

If the PLMN has configured secondary RAT usage reporting, the MME shall perform step 7 through 10 before step 2 onwards. If the PDN connection was served by a P-GW, the EPS Bearers in the Serving-GW for the particular PDN connection are deactivated by the MME by sending Delete Session Request (Cause, LBI, User Location Information (ECGI), Secondary RAT usage data) to the Serving-GW. This message indicates that all bearers belonging to that PDN connection shall be released. If the UE Time Zone has changed, the MME includes the UE Time Zone IE in this message. For PDN connection to the SCEF the MME indicates to the SCEF the connection for the UE is no longer available according to TS 23.682 and steps 2,3,4,5,6 are not executed. If the MME received Secondary RAT usage data in step 9b, the MME shall include it in this Delete Session Request message.

The Serving-GW sends Delete Session Request (Cause, LBI, User Location Information (ECGI), Secondary RAT usage data) to the PDN-GW. The S-GW also includes User Location Information IE and/or UE Time Zone IE if it is present in step 2. The Serving-GW also includes the Secondary RAT usage data in this message if it was present in step 2 and if PDN-GW secondary RAT usage data reporting is active.

The PDN-GW acknowledges with Delete Session Response (optionally, APN Rate Control Status).

The PDN-GW employs the PCEF-initiated IP-CAN Session Termination procedure as defined in TS 23.203 to indicate to the PCRF that the IP-CAN session is released if PCRF is applied in the network. If requested the PDN-GW indicates User Location Information and/or UE Time Zone Information to the PCRF as defined in TS 23.203.

The Serving-GW acknowledges with Delete Session Response (optionally, APN Rate Control Status). If received, the MME stores the APN Rate Control Status in the MM context.

If the UE is in ECM-IDLE state and the PDN disconnection is decided by the MME, the MME shall delete the corresponding contexts of the PDN connection locally, steps 7 to 10b are skipped except if the MME has decided to restore certain PDN connections as specified in TS 23.007 or for other reasons e.g. SIPTO. The MME initiates the deactivation of all Radio Bearers associated with the PDN connection to the eNodeB by sending the Deactivate Bearer Request message to the eNodeB. The MME shall re-calculate the UE-AMBR (see clause 4.7.3). This S1-AP message carries the list of EPS bearers to be released, the new UE-AMBR, and a NAS Deactivate EPS Bearer Context Request (LBI) message. The MME builds a NAS message Deactivate EPS Bearer Context Request including the EPS Bearer Identity, and includes it in the S1-AP Deactivate Bearer Request message. If the network wants to trigger GW relocation (e.g. for SIPTO), the NAS message Deactivate EPS Bearer Context Request includes the request for reactivation of the same PDN connection via the same APN by the UE. If the MME released the PDN connection due to failed bearer set up during handover, the UE and the MME deactivate the failed contexts locally without peer-to peer ESM signalling.

The eNodeB sends the RRC Connection Reconfiguration message including the corresponding bearers to be released and the NAS Deactivate EPS Bearer Context Request (LBI) message to the UE.

The UE releases all resources corresponding to the PDN connection and acknowledges this by sending the RRC Connection Reconfiguration Complete message to the eNodeB.

The eNodeB sends an acknowledgement of the deactivation to the MME. If the PLMN has configured secondary RAT usage reporting and the eNodeB has Secondary RAT usage data to report, the Secondary RAT usage data is included.

The UE NAS layer builds a Deactivate EPS Bearer Context Accept message. The UE then sends a Direct Transfer (Deactivate EPS Bearer Context Accept) message to the eNodeB. If the Deactivate EPS Bearer Context Request message from the MME indicated reactivation requested, the UE starts the UE initiated PDN connection request procedure as specified in clause 5.10.2 by using the same APN of the released PDN connection.

The eNodeB sends an Uplink NAS Transport (Deactivate EPS Bearer Context Accept) message to the MME.

The Serving-GW relocation procedure may be triggered by the MME due to events that may benefit from a Serving-GW relocation other than those described in the mobility events scenarios.

If the MME determines that the Serving-GW is to be relocated then it selects a new Serving-GW according to clause 4.3.8.2. The MME sends a Create Session Request (bearer context(s) with PDN-GW addresses and TEIDs (for GTP-based S5/S8) or GRE keys (for PMIP-based S5/S8) at the PDN-GW(s) for uplink traffic, eNodeB address(es) and TEIDs for downlink user plane for the existing EPS bearers, the Protocol Type over S5/S8, Serving Network) message per PDN connection to the new Serving-GW. The new Serving-GW allocates the S-GW addresses and TEIDs for the uplink traffic on S1_U reference point (one TEID per bearer). The Protocol Type over S5/S8 is provided to Serving-GW which protocol should be used over S5/S8 interface. If the PDN-GW requested UE's location info, the MME also includes the User Location Information IE in this message. If the PDN-GW requested UE's User CSG information (determined from the UE context), the MME includes the User CSG Information IE in this message if the User CSG Information has changed.

The new Serving-GW assigns addresses and TEIDs (one per bearer) for downlink traffic from the PDN-GW. The Serving-GW allocates DL TEIDs on S5/S8. It sends a Modify Bearer Request (Serving-GW addresses for user plane and TEID(s), Serving Network) message per PDN connection to the PDN-GW(s). The S-GW also includes User Location Information IE and/or UE Time Zone IE and/or User CSG Information IE if it is present in step 2. The PDN-GW updates its context field and returns a Modify Bearer Response (Charging Id, MSISDN, etc.) message to the Serving-GW. The MSISDN is included if the PDN-GW has it stored in its UE context. The PDN-GW starts sending downlink packets to the new GW using the newly received address and TEIDs. These downlink packets will use the new downlink path via the new Serving-GW to the eNodeB. This step is performed for all connected PDN-GWs for that specific UE.

The new Serving-GW sends a Create Session Response (Serving-GW addresses and uplink TEID(s) for user plane) message back to the MME. The MME starts a timer, to be used in step 6.

The MME sends a Bearer Modify Request (Serving-GW addresses and uplink TEID(s) for user plane, Secondary RAT usage data request) message to eNodeB. The eNodeB starts using the new Serving-GW address(es) and TEID(s) for forwarding subsequent uplink packets and sends a Bearer Modify Response message to the MME. If the PLMN has configured secondary RAT usage reporting, the MME may request the eNodeB for Secondary RAT usage data in the Bearer Modify request message. If the eNodeB has Secondary RAT usage data, it provides it in the Bearer Modify Response message.

If Secondary RAT usage data is included in the previous message and if PDN-GW Secondary RAT usage reporting is active, the MME uses the Secondary RAT usage data reporting procedure as described in clause 5.7A.3 Figure 5.7A.3-2 to provide this information to the Serving-GW and PDN-GW. The MME includes a flag that the Serving-GW shall not process this information and forward it to the PDN-GW.

When the timer has expired after step 4, the MME releases the bearer(s) in the old Serving-GW by sending a Delete Session Request message (Cause, Operation Indication, Secondary RAT usage data). The operation Indication flag is not set, that indicates to the old Serving-GW that the old Serving-GW shall not initiate a delete procedure towards the PDN-GW. The old Serving-GW acknowledges with Delete Session Response messages. The MME includes the Secondary RAT usage data if the eNodeB had provided it to the MME in step 5.