Patent Description:
Document "<NPL>), and further document <NPL>), both provide background information concerning signalling including Access Type.

In accordance with the present invention, a method, an apparatus and a computer program, as set forth in the independent claims, respectively, are provided. Additional embodiments of the invention are described in the dependent claims.

Communication systems that operate according to Fifth Generation (<NUM>) standards permit user equipment to maintain independent registrations to the <NUM> core network via Third Generation Partnership Project (3GPP) access according to 3GPP access protocols and via non-3GPP access according to non-3GPP access protocols. The user equipment can be either registered to the <NUM> core network via 3GPP access or registered to the <NUM> core network via non-3GPP access, or concurrently registered to the <NUM> core network via 3GPP and non-3GPP accesses. The 3GPP and non-3GPP protocols support a registration management (RM)-registered and connection management (CM)-connected state in which the user equipment has a signaling communication channel with the <NUM> core network, an RM-registered and CM-idle state in which the user equipment is registered with the <NUM> core network but does not have a signaling communication channel with the <NUM> core network, and a RM-de-registered state in which the user equipment is not registered with the <NUM> core network.

Non-access stratum (NAS) signaling between the <NUM> core network and the user equipment is conveyed to the user equipment in NAS containers formed by a network function (NF) such as a session management function (SMF) that manages the PDU sessions (for both the 3GPP and non-3GPP accesses), SMS function (SMSF) that manages the short message service (SMS) (for both the 3GPP and non-3GPP accesses), or a location management function (LMF) that manages user equipment (UE) positioning services. Over each of 3GPP and non-3GPP access, when the user equipment (UE) is in RM-registered and CM-Connected state, the user equipment is reachable from the <NUM> core network via (NAS) signaling sent over that access. However, the non-3GPP access differs from the 3GPP access because user equipment can be paged by the <NUM> core network via 3GPP access but cannot be paged via non 3GPP access. Furthermore, policy rules associated to a PDU session may require the SMF to form the NAS signaling sent to the UE. The rules are generated for the SMF by a policy control function (PCF) that performs policy and charging control (PCC).

Network Functions (NF) and NF services send NAS signaling to the UE or N2 UE related signaling to the <NUM>-AN (<NUM> Access Network) serving the UE via a common service (supported by the AMF - Access and Mobility control Function). The N2 UE related signaling corresponds to signaling sent by the <NUM> core to the <NUM>-AN (Access Network) serving a UE on a given access. The Network Functions (NF) and NF services that send NAS signaling to the UE or N2 UE related signaling to the <NUM>-AN (<NUM> Access Network) serving the UE are called consumers of the NAS and/or N2 transfer service.

Examples of consumers of the NAS and/or N2 transfer service are:.

However, different consumers of the NAS and/or N2 transfer service may have different needs with regard to which access (3GPP or Non 3GPP or any of them) may be used to transfer signaling to the UE. For example, a SMSF does not care of the access used to send a SMS to the UE; a PCF may not care of the access used to send policies to the UE; other NAS signaling, such as for location management functions, are specific to 3GPP access. Conversely, when NAS and N2 signaling is access dependent (e.g. the QoS parameters of a PDU Session depend on the access type currently serving that PDU Session) the SMF may control which access is used for NAS and N2 signaling it requests to send. Some NAS and N2 signaling related with PDU sessions is specific to an access type (e.g. non-3GPP) because the PCC rules for 3GPP access differ from the PCC rules for non-3GPP access. As opposed to that, some NAS and N2 signaling related with PDU sessions does not depend on the access type, such as signaling related to the release of a PDU Session. Furthermore, the decision of the NAS and/or N2 transfer service about which access to use should not depend on the type of consumer of the NAS and/or N2 transfer service because a service should be transparent to which entity requires it.

One solution to this the aforementioned problems is to that the AMF reject all NAS containers received from the SMF when the user equipment cannot be reached via an access type indicated by an identifier of the PDU session included in a header of the container. This approach adds additional signaling, which is unnecessary if the NAS container includes information that can be conveyed using the access type of an available PDU session such as PDU session release NAS containers or mobile terminated SMS message NAS containers. Furthermore, the SMF does not know whether the PCC rules used to form a NAS container according to one access type can be applied for NAS containers that are transmitted over other access types. Thus, if the AMF indicates that the access type is to be changed, the SMF is required to contact the PCF to update the PCC rules for the new access type. The additional signaling is unnecessary if the previously received PCC rules can be used to form NAS containers of both types.

Another problem arises when an SMS function (SMSF) or a location management function (LMF) attempts to send a non-3GPP specific NAS container to a user equipment. When the AMF receives a message that contains the NAS container and some additional parameters (e.g., as specified in TS <NUM> v15. <NUM> clause <NUM>. <NUM>) transmitted by the SMSF or LMF, the AMF is unable to determine whether the NAS container is specific to 3GPP access (in the case of LMF), is specific to non-3GPP access, or is access independent (in the case of SMSF) because none of the additional parameters transmitted with the NAS container include information indicating an access type for the message included in the NAS container.

<FIG> disclose embodiments of a communication system in which access type control information is added to network function (NF) requests to send (NAS) signaling to the user equipment and/or N2 (NGAP) signaling to the access network that serves the user equipment. The access type control information allows the AMF to determine whether the NAS container is specific to 3GPP access, is specific to non-3GPP access, or is access independent. In some embodiments, the access type control information applies to enforce that NAS/N2 responses from the NF in a <NUM> core network shall be sent by the AMF on the same access as the one on which the NAS/N2 request has been received from the user equipment or access network that serves the user equipment. The access type parameter also eliminates or reduces unnecessary signaling between an access and mobility management function (AMF) and a session management function (SMF). Values of the parameter indicate an access type associated with the NAS container. In some embodiments, the value of the parameter indicates whether the NAS container is to be sent using 3GPP access, non-3GPP access, or either access type. In some embodiments, the AMF receives a service request from the user equipment in response to paging the user equipment or transmitting an NAS notification indicating non-3GPP access. The service request includes a list of PDU sessions associated with the user equipment. The list also indicates the PDU sessions that are transferable from non-3GPP access to 3GPP access.

The AMF receives a NAS container from the SMF and accesses the access type parameter in the message that carries the NAS container. If the access type indicates that the NAS container can be sent according to either 3GPP access or non-3GPP access and the list included in the service request indicates that the associated PDU session can be transferred to 3GPP access, the AMF switches the PDU session from non-3GPP to 3GPP access and forwards the NAS container to the user equipment via 3GPP access. If the access type indicates that the NAS container is to be sent using non-3GPP access and should not be sent using 3GPP access, the AMF rejects the NAS container and sends a message to the SMF indicating that the access type can be changed from non-3GPP access to 3GPP access. In response, the SMF generates a new NAS container according to policy and charging control (PCC) rules for 3GPP access. For example, the SMF can generate a request for new PCC rules for 3GPP access from a policy control function (PCF). In some embodiments, the PCF also transmits a parameter that indicates whether the PCC rules apply to both 3GPP access and non-3GPP access or are specific to one access. Alternatively, the PCF can transmit PCC rules for both 3GPP access and non-3GPP access in response to a request from the SMF. Either approach potentially reduces signaling between the SMF and the PCF.

<FIG> is a block diagram of a communication system <NUM> that supports selectively transmitting NAS containers via 3GPP access or non-3GPP access according to some embodiments. The communication system <NUM> provides support for both mobile and fixed access. As used herein, the term "mobile access" refers to accessing a communication system (e.g., the communication system <NUM>) over an air interface. Mobile access can therefore be referred to as wireless access, mobile communication, wireless communication, or referred to with other similar terms. The term "fixed access" refers to accessing to a communication system using a device that is physically connected to the communication system, e.g., accessing a communication system such as the communication system <NUM> via wires, optical fibers, and the like. Fixed access can therefore be referred to as wireline access, wired communication, or referred to with other similar terms. The communication system <NUM> supports hybrid access that allows devices to concurrently access the communication system <NUM> using mobile access and fixed access. Some embodiments of the communication system <NUM> support 3GPP radio access and non-3GPP (wireless or fixed) access on an equal footing. User equipment will therefore be able to perform dual access by connecting to the <NUM> core network via concurrent 3GPP radio access and non-3GPP (wireless or fixed) access.

The communication system <NUM> includes a core network <NUM> that is accessible by either mobile or fixed devices using a common user plane access and a control plane that supports common authentication, authorization, and accounting (AAA) and policy control. The core network <NUM> includes an access and mobility management function (AMF) <NUM> that manages access control and mobility for devices in the communication system <NUM>. Some embodiments of the AMF <NUM> handle registration management (RM) and connection management (CM) tasks, as discussed in detail below. The core network <NUM> also includes a session management function (SMF) <NUM> to set up and manage sessions in the communication system <NUM> according to network policies. An association between user equipment and the core network <NUM> can be represented as a packet data unit (PDU) session that can be managed by the SMF <NUM>. The PDU session supports data connectivity between user equipment and a data network. The SMF <NUM> generate messages including NAS containers for transmission to the AMF <NUM>. As discussed in detail below, the messages are associated with information that indicates whether the NAS containers are to be transmitted via 3GPP access, non-3GPP access, or both types of access.

The core network <NUM> also includes one or more user plane functions (UPF) <NUM> that can be deployed in the communication system <NUM> to provide services to users of the communication system <NUM>. The core network <NUM> further includes a unified data manager (UDM) <NUM> that processes credentials, location management, subscription management, and the like. The UDM <NUM> stores data including user subscription data, such as subscription identifiers, security credentials, access and mobility related subscription data, and session related subscription data. Some embodiments of the core network <NUM> include other functionality such as a policy control function and a network function repository function, which are not shown in <FIG> in the interest of clarity. Some embodiments of the core network <NUM> are implemented using network function virtualization and software defined networking, as discussed herein. For example, different network slices can be used to instantiate different instances of the AMF <NUM>, the SMF <NUM>, the UPF <NUM>, or the UDM <NUM> for different users or devices. Each PDU session is part of one network slice.

In the illustrated embodiment, a user equipment <NUM> has a wireless connection <NUM> to an access point <NUM>. The wireless connection <NUM> is a non-3GPP access type such as a Wi-Fi connection. The access point <NUM> has a wired (non-3GPP) connection to network <NUM> that is capable of carrying Internet protocol (IP) traffic such as an Ethernet network. Some embodiments of the wired connection use line termination devices such as a digital subscriber line access multiplexer (DSLAM) or a gigabit passive optical network (GPON). The communication system <NUM> can therefore provide the user equipment <NUM> with access to the core network <NUM> via a non-3GPP access type.

The communication system <NUM> can also provide the user equipment 130with mobile access to the core network <NUM>, e.g., via a radio access network <NUM> that is connected to the AMF <NUM> over a corresponding interface such as an N2 interface. The radio access network <NUM> is also connected to the UPF <NUM> by a corresponding interface such as an N3 interface, which is not shown in <FIG> in the interest of clarity. The radio access network <NUM> provides wireless connectivity to the user equipment <NUM> via a wireless connection <NUM>. The wireless connections <NUM> provides wireless connectivity according to a 3GPP access type.

An interworking function <NUM> is disposed between the network <NUM> and the core network <NUM>. The interworking function <NUM> can also be referred to as a non-3GPP interworking function (N3IWF) because the interworking function <NUM> is used to connect the core network <NUM> to the access point that provides connectivity via non-3GPP access types. The interworking function <NUM> is configured to modify or translate messages conveyed from the fixed access user equipment to the core network <NUM> so that the fixed access user equipment appears to be accessing the core network <NUM> according to 3GPP standards or protocols from the perspective of the core network <NUM>. The interworking function <NUM> is also configured to modify or translate messages conveyed from the core network <NUM> to the fixed access user equipment so that the messages received by the fixed access user equipment conform to corresponding non-3GPP standards or protocols. The interworking function <NUM> supports interfaces with the AMF <NUM> and the UPF <NUM>.

The SMF <NUM> generates NAS containers and transmits the NAS containers to the AMF <NUM> and NAS messages. As used herein, an NAS layer is understood to be a protocol layer implemented in wireless communication protocol stacks between user equipment <NUM> and the core network <NUM>. The NAS layer is the highest stratum of the control plane between the user equipment <NUM> and a mobility management entity (MME) or the AMF <NUM> at the radio interface. The NAS layer manages the establishment of communication sessions and maintains continuous communication as the user equipment moves through the network. Examples of functions supported by the NAS protocols include mobility of the user equipment <NUM> and session management procedures that are used to establish and maintain connectivity between the user equipment and a packet data network via the mobile data network. In contrast, an access stratum (AS) layer and corresponding AS protocol are used to convey information over an air interface in the wireless portion of the network. The NAS protocol is transported using radio resource control (RRC) messages in Second Generation (<NUM>), Third Generation (<NUM>), Fourth Generation (<NUM>), and <NUM> networks that operate according to the standards defined by the Third Generation Partnership Project (3GPP).

One or more NAS links are used to convey NAS messages between the user equipment <NUM>, <NUM> and the AMF <NUM>, which are the terminating endpoints of the NAS links. The user equipment <NUM> can therefore communicate with the core network <NUM> using NAS messages that are conveyed via a first NAS link that traverses the access point <NUM>. Some embodiments of the user equipment <NUM> support multiple concurrent NAS links with the AMF <NUM>. For example, the user equipment <NUM> and the AMF <NUM> can concurrently support a mobile NAS link and a non-3GPP NAS link.

Prior to establishing an NAS link, the user equipment <NUM> transmits an NAS registration message to register with the AMF <NUM>. The NAS registration message can include information that is used to perform authorization (and, in some cases, authentication) of the user equipment. The registration message can also be used to register the user equipment with an SMS service function (SMSF) <NUM> for SMS messaging. Registration of the user equipment with the AMF <NUM> also includes generating or provisioning an encryption key and an integrity key for the user equipment and the AMF <NUM>. The encryption key and the integrity key are used to provide secure transfer over the NAS link, as discussed herein.

Once registered, the user equipment <NUM> is registration management (RM)-connected. The user equipment <NUM> can subsequently establish connectivity with the AMF <NUM> via the <NUM>-AN (Access Network) supporting an Access Type, in which case the user equipment <NUM> is connection management (CM)-connected over that Access Type. The user equipment <NUM> can also be in an RM-connected CM-idle state (in which case there is no established signaling path to carry NAS signaling over the access). However, the non-3GPP protocols differ from the 3GPP protocols because the UE cannot be paged via non-3GPP access in this state (so cannot be put CM-Connected under request of the <NUM> Core), whereas a user equipment <NUM> in the 3GPP RM-registered CM-idle state can be paged by the core network <NUM> via 3GPP access.

As discussed above, several problems arise due to the distinction between 3GPP and non-3GPP access types. At least in part to address these problems, services that are responsible for sending signaling to the user equipment <NUM> or an access network <NUM> serving the user equipment <NUM> receive requests to send the signaling to the user equipment <NUM> or the access network together with access type control information indicating whether the signaling may be sent using any access type or is to be sent using a specific access type provided in the request. In some embodiments, the service is implemented in the AMF <NUM>, The AMF <NUM> receives a request to transfer N2 and/or NAS messages from the SMF <NUM> including NAS and/or N2 containers and an access type control parameter that indicates whether the N2 and/or NAS container is to be sent using only non-3GPP access, only 3GPP access, or if it may be transmitted using either non-3GPP access or 3GPP access.

The service that is responsible for sending the signal then selectively forwards the signaling to the user equipment <NUM> or the access network <NUM> based on the access type control information. The access type control information indicates whether the signaling is transmittable via any of a plurality of access types (such as 3GPP and non-3GPP) or a specific access type, e.g., only via non-3GPP access. In some cases, and according to the invention, the service detects that it is not possible to send the signaling via the specific access type provided in the request when at least one of following conditions applies:.

If the access type control parameter indicates that the N2 and/or NAS container may be transmitted using using any of the plurality of access types (e.g. using ither non-3GPP access or 3GPP access), the service tries to send the signaling via a first one of the plurality of access types and when this is not possible it tries to send the signaling via a second one of the plurality of access types.

<FIG> is a block diagram of an NFV architecture <NUM> according to some embodiments. The NFV architecture <NUM> is used to implement some embodiments of the communication system <NUM> shown in <FIG>. The NFV architecture <NUM> includes hardware resources <NUM> including computing hardware <NUM> such as one or more processors, storage hardware <NUM> such as one or more memories, and network hardware <NUM> such as one or more transmitters, receivers, or transceivers. A virtualization layer <NUM> provides an abstract representation of the hardware resources <NUM>. The abstract representation supported by the virtualization layer <NUM> can be managed using a virtualized infrastructure manager <NUM>, which is part of the NFV management and orchestration (M&O) module <NUM>. Some embodiments of the manager <NUM> are configured to collect and forward performance measurements and events that may occur in the NFV architecture <NUM>. For example, performance measurements may be forwarded to an orchestrator (ORCH) <NUM> implemented in the NFV M&O <NUM>. The hardware resources <NUM> and the virtualization layer <NUM> may be used to implement virtual resources <NUM> including virtual computing <NUM>, virtual storage <NUM>, and virtual networking <NUM>.

Virtual networking functions (VNF1, VNF2, VNF3) run over the NFV infrastructure (e.g., the hardware resources <NUM>) and utilize the virtual resources <NUM>. For example the virtual networking functions (VNF1, VNF2, VNF3) may be implemented using virtual machines supported by the virtual computing resources <NUM>, virtual memory supported by the virtual storage resources <NUM>, or virtual networks supported by the virtual network resources <NUM>. Element management systems (EMS1, EMS2, EMS3) are responsible for managing the virtual networking functions (VNF1, VNF2, VNF3). For example, the element management systems (EMS1, EMS2, EMS3) may be responsible for fault and performance management. In some embodiments, each of the virtual networking functions (VNF1, VNF2, VNF3) is controlled by a corresponding VNF manager <NUM> that exchanges information and coordinates actions with the manager <NUM> or the orchestrator <NUM>.

The NFV architecture <NUM> may include an operation support system (OSS)/business support system (BSS) <NUM>. The OSS/BSS <NUM> deals with network management including fault management using the OSS functionality. The OSS/BSS <NUM> also deals with customer and product management using the BSS functionality. Some embodiments of the NFV architecture <NUM> use a set of descriptors <NUM> for storing descriptions of services, virtual network functions, or infrastructure supported by the NFV architecture <NUM>. Information in the descriptors <NUM> may be updated or modified by the NFV M&O <NUM>.

The NFV architecture <NUM> can be used to implement network slices that provide control plane functions, such as instances of the AMF <NUM>, the SMF <NUM>, the UPF <NUM>, or the UDM <NUM> shown in <FIG>. A network slice is a complete logical network that provides communication services and network capabilities, which can vary from slice to slice. User equipment can concurrently access multiple slices. Some embodiments of user equipment provide Network Slice Selection Assistance Information (NSSAI) parameters to the network to assist in selection of a slice instance for the user equipment. A single NSSAI may lead to the selection of several slices. The NFV architecture <NUM> can also use device capabilities, subscription information and local operator policies to do the selection. An NSSAI is a collection of smaller components, Single-NSSAIs (S-NSSAI), which each include a Slice Service Type (SST) and possibly a Slice Differentiator (SD). Slice service type refers to an expected network behavior in terms of features and services (e.g., specialized for broadband or massive loT), while the slice differentiator can help selecting among several network slice instances of the same type, e.g. to isolate traffic related to different services into different slices.

<FIG> is a flow diagram of a first portion of a method <NUM> of selectively transmitting an NAS container based on access type control information associated with an NAS message that includes the NAS container and encompasses the invention. The method <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. An AMF is used as an example of a service that is responsible for providing signaling to a user equipment or and access network serving the user equipment. However, in other cases, other entities are used to implement the service.

At block <NUM>, the AMF transfer service receives a service request to transfer signaling. The AMF transfer service also receives associated access type control information such as an access type parameter.

At decision block <NUM>, the AMF determines whether the access type control information indicates that a specific access type is to be used for transmitting the NAS container. If so, the method <NUM> flows to decision block <NUM>. If the access type control information does not indicate that a specific access type is to be used, e.g., the access type control information indicates that any of a set of access types can be used, the method <NUM> flows to node <NUM> (see <FIG>).

At decision block <NUM>, the AMF determines whether the user equipment is connected on the access type specified in the access type control information. If so, the method <NUM> flows to block <NUM> and signaling (such as the NAS message) is transmitted via the specific access type indicated by the access type control information. If the user equipment is not connected, the method <NUM> flows to decision block <NUM>.

At decision block <NUM>, the user equipment is paged (if possible). The AMF determines whether the paging attempt succeeded and the user equipment is connected via the access type used for the paging attempt. If so, the method <NUM> flows to block <NUM> and signaling (such as the NAS message) is transmitted via the access type used for the paging attempt. If not, e.g., if the user equipment cannot be paged or the page is not successful, the method <NUM> flows to block <NUM> and the service request is rejected, as per the invention.

<FIG> is a flow diagram of a second portion of the method <NUM> of selectively transmitting an NAS container based on access type control information associated with an NAS message that includes the NAS container according to some optional embodiments. The second portion of the method <NUM> begins at the node <NUM>, which corresponds to the node <NUM> shown in <FIG>. As discussed above, the method <NUM> flows to node <NUM> in response to the access type control information indicating that any of a set of access types can be used to transmit signaling such as the NAS message.

At block <NUM>, the AMF generates an ordered list of the access types indicated in the access type control information. The access types can be ordered based on any criteria including priorities associated with the different access types. At block <NUM>, the AMF selects an access type from the ordered list of access types. For example, the AMF can select the highest priority access type remaining in the ordered list of access types.

At decision block <NUM>, the AMF determines whether the user equipment is connected on the access type that was selected in block <NUM>. If so, the method <NUM> flows to the block <NUM> and signaling (such as the NAS message) is transmitted via the selected access type. If not, the method <NUM> flows to decision block <NUM>.

At decision block <NUM>, the user equipment is paged (if possible). The AMF determines whether the paging attempt succeeded and the user equipment is connected via the access type used for the paging attempt. If so, the method <NUM> flows to block <NUM> and signaling (such as the NAS message) is transmitted via the access type used for the paging attempt. If not, e.g., if the user equipment cannot be paged or the page is not successful, the method <NUM> flows to block <NUM>.

At decision block <NUM>, the AMF determines whether there are more access types in the ordered list that have not been used for a connection attempt. If so, the method <NUM> flows to block <NUM> and another access type is selected from the ordered list of access types. If not, the method <NUM> flows to block <NUM> and the service request is rejected.

<FIG> is a block diagram of an NAS message <NUM> that is associated with an access type parameter <NUM> according to some embodiments. The NAS message <NUM> includes an NAS container <NUM> and is transmitted from an SMF to an AMF, such as the SMF <NUM> and the AMF <NUM> shown in <FIG>. The AMF selectively forwards the NAS container <NUM> based on a value of the access type parameter <NUM>. For example, if the user equipment that is receiving the NAS container <NUM> is in an RM-registered, CM-idle mode for non-3GPP access, the AMF forwards the NAS container <NUM> via 3GPP access in response to the access type parameter <NUM> indicating that the NAS container <NUM> is transmittable via 3GPP access or both non-3GPP and 3GPP access. In the illustrated embodiment, a header <NUM> includes other information such as an identifier of the user equipment, an identifier of a PDU session used to transmit the message <NUM>, and the like.

<FIG> is a block diagram of a list <NUM> of PDU sessions that is transmitted from a user equipment to an AMF and the service request according to some embodiments. The list <NUM> is transmitted by some embodiments of the user equipment <NUM>, <NUM> shown in <FIG>. The list <NUM> includes identifiers of PDU sessions that are available at the user equipment. For example, the list <NUM> identifies PDU sessions <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> that are available to the user equipment for non-3GPP access. In the illustrated embodiment, the list <NUM> also includes information indicating which of the PDU sessions <NUM>-<NUM> are transferable from non-3GPP access to 3GPP access. For example, the information indicates that the PDU sessions <NUM>, <NUM>, <NUM>, <NUM> are transferable from non-3GPP access to 3GPP access.

<FIG> is a message flow <NUM> for a user equipment triggered service access procedure according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the illustrated embodiment, the message flow <NUM> represents a service request procedure that is triggered by the user equipment and used to send uplink signaling messages or as a response to a network paging request. In the interest of clarity, some of the messages used in the service request procedure are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

The user equipment initiates the service request procedure by transmitting a service request <NUM> to a radio access network (RAN). The service request <NUM> includes a list of PDU sessions to be activated, a list of allowed PDU sessions, security parameters, PDU session status, and the like. Some embodiments of the service request <NUM> also include information indicating which of the PDU sessions is transferable from non-3GPP access to 3GPP access.

The RAN then transmits a message <NUM> including (or based upon) the service request <NUM> received from the user equipment. The message <NUM> is transmitted to an AMF that is registered with the user equipment. For example, the user equipment can be RM-registered with the AMF for 3GPP access and non-3GPP access. In some cases, such as when the service request <NUM> was not sent with integrity protection or verification of the integrity protection failed, the AMF performs (at block <NUM>) an authentication and authorization process. For example, the AMF can generate a security context for the user equipment.

The AMF transmits a request <NUM> to update a context for a PDU session associated with the user equipment. The request <NUM> includes PDU session identifiers, operation types, location information for the user equipment, an access type, a radio access technology type, presents information, and the like.

The information conveyed in the request <NUM> depends on whether the paging or notification of the user equipment indicated non-3GPP access. If the procedure was triggered in response to paging or NAS Notification indicating non-3GPP access, and the PDU Session for which the user equipment was paged or notified is not in the List Of Allowed PDU Sessions provided by the user equipment, the AMF notifies the SMF that that the user equipment is not reachable. For other PDU Sessions in the List Of Allowed PDU Sessions the Service Request Procedure succeeds without re-activating the User Plane of any PDU Sessions. If the procedure was triggered in response to paging or NAS notification indicating non-3GPP access, and the PDU Session for which the UE was paged or notified is in the List Of Allowed PDU Sessions provided by the UE, the AMF proceeds as follows:.

In some embodiments, the SMF initiates a policy association modification <NUM>, which is a conditional step and is not necessarily performed in all cases. If the AMF notified the SMF that the access type of the PDU session can be changed from non-3GPP to 3GPP, and if PCC is deployed, the SMF shall perform an SMF initiated SM Policy Association Modification procedure (as defined in clause <NUM>. <NUM> of TS <NUM>) to provide information on the Policy Control Request Trigger condition(s) that have been met (e.g. change of Access Type in the case of PDU session(s) moved from 3GPP access to non-3GPP access. The PCF may provide updated PCC Rule.

For a PDU Session for which the SMF has determined that a new N1 SM container has to be sent again over the new access, the AMF shall send the N1 SM Container after the service request procedure is completed, using Downlink NAS Transport message (as part of related SM procedures, not shown in the call flow).

For a PDU Session that the SMF has determined to accept the activation of a user plane (UP) connection, N2 SM Information is sent in a subsequent message <NUM>.

At block <NUM>, the SMF performs configuration of a UPF. In some cases, configuring the UPF includes selecting a UPF, changing from one UPF to a new UPF, and the like.

The SMF responds to the request <NUM> by transmitting a response <NUM>. Some embodiments of the message are a PDU session update context response message that includes information such as PDU session identifiers, quality-of-service (QoS) profiles, network slice identifiers, and the like.

The AMF transmits a request <NUM> that includes information received from the SMF in the response <NUM>, security context, network slice information for the access type of the user equipment, and the like.

At step <NUM>, the RAN performs radio resource control (RRC) connection reconfiguration with the user equipment, which may depend on the QoS information for all the QoS flows of the PDU sessions of activated uplink connections. Uplink data transmission is performed in block <NUM>.

<FIG> is a message flow <NUM> for a network triggered service access request according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the illustrated embodiment, the message flow <NUM> represents a service request procedure that is triggered by the network when the network needs to signal to deliver mobile terminating user data. In the interest of clarity, some of the messages used in the service request procedure are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

A UPF receives downlink data <NUM> that is addressed to a user equipment. In response to receiving the downlink data <NUM>, the UPF sends a data notification <NUM> that includes a session identifier, QoS information for the downlink packets, and the like. The data notification <NUM> is sent to an SMF, which acknowledges receipt of the data notification <NUM> by transmitting a data notification acknowledgment <NUM> to the UPF. In response to receiving the data notification acknowledgment <NUM>, the UPF forwards the downlink packets to the SMF at step <NUM>.

In the illustrated embodiment, the SMF sends an NAS message <NUM> to the AMF that includes a PDU session identifier and an access type parameter that indicates allowed access types for transmitting an NAS container included in the NAS message <NUM>. For example, the access type parameter can indicate that the NAS container is only transmittable via 3GPP access, only transmittable via non-3GPP access, or transmittable via either 3GPP or non-3GPP access. As discussed herein, the SMF is an example of a network function (NF) and in some embodiments the NF sends the NAS message <NUM> to the AMF including the PDU session identifier and the access type parameter.

The AMF response to the NAS message <NUM> by transmitting a response <NUM> to the SMF. The contents of the response <NUM> depend on the state of the user equipment.

The SMF transmits a message <NUM> in response to receiving the response <NUM>. If the SMF receives an indication from the AMF that the UE is unreachable or reachable only for regulatory prioritized service, the message <NUM> transmitted by the SMF may, based on network policies, either:.

If the user equipment is in a CM-connected state and the access associated with the PDU session identifier received from the SMF, the user plane connection for this PDU session is activated at step <NUM>.

If the user equipment is in a CM-idle state in 3GPP access and the PDU session identifier received from the SMF is associated with 3GPP access, the AMF sends a notification <NUM> to RAN, which then sends a notification <NUM> to the user equipment. For example, the AMF can page the user equipment.

If the user equipment is concurrently registered over a 3GPP and non-3GPP access is in the same public land mobile network (PLMN) and the user equipment is in eight CM-connected state in 3GPP access and the PDU session identifier is associated with non-3GPP access, the AMF sends a NAS notification <NUM> containing the non-3GPP access type to the user equipment.

If the user equipment does not respond to the notification <NUM> within a predetermined time interval (e.g., as indicated by a timer that is initiated in response to sending the NAS notification <NUM>), the AMF sends a failure notification <NUM> to the SMF.

The user equipment initiates a user equipment triggered service request procedure (as discussed herein with regard to <FIG>) at block <NUM>. The UPF then transmits buffered downlink data <NUM> towards the user equipment via the RAN that perform the service request procedure.

<FIG> is a message flow <NUM> for PDU session establishment in non-roaming and roaming cases according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for PDU session establishment are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

The user equipment transmits a PDU session establishment request <NUM> to the AMF, which selects an SMF to support the session at block <NUM>.

The AMF transmits a PDU session request <NUM> that is used to instruct the SMF to create a context for the PDU session. The SMF registers the PDU session with a UDM, as indicated by the double-headed arrow <NUM>. The SMF then provides a response <NUM> to the request <NUM> indicating that the PDU session establishment request has been processed.

In some embodiments, an authorization/authentication procedure is performed at block <NUM> to authorize and authenticate the user equipment for communication in the network. A session establishment process is then performed at block <NUM>. The message exchange is performed in blocks <NUM>, <NUM> are disclosed in more detail in 3GPP TS <NUM>.

The SMF sends a message <NUM> to the AMF including a PDU session identifier and an access type parameter indicating allowed access type for the associated PDU session. In some embodiments, the SMF sends an Namf_Communication _N1N2MessageTransfer (PDU Session ID, Allowed Access Type, N2 SM information (PDU Session ID, QFI(s), QoS Profile(s), CN Tunnel Info, S-NSSAI from the Allowed NSSAI, Session-AMBR, PDU Session Type, User Plane Security Enforcement information, UE Integrity Protection Maximum Data Rate), N1 SM container (PDU Session Establishment Accept (QoS Rule(s) and QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s), selected SSC mode, S-NSSAI(s), DNN, allocated IPv4 address, interface identifier, Session-AMBR, selected PDU Session Type, Reflective QoS Timer (if available), P-CSCF address(es)))). If multiple UPFs are used for the PDU Session, the CN Tunnel Info contain tunnel information related with the UPF that terminates N3.

The Namf_Communication _N1N2MessageTransfer contains the Allowed Access Type allowing the AMF to know which access towards the UE to use.

The AMF transmits a response <NUM> to the message <NUM>. The AMF also sends a PDU session request as an NAS message <NUM> to the RAN, which performs a resource set up procedure <NUM> with the user equipment. Once the user equipment has been configured for the PDU session, the user equipment responds with a PDU session request acknowledgment <NUM>. Uplink and downlink data are then exchanged in the block <NUM>.

<FIG> is a message flow <NUM> for user equipment or network requested PDU session modification according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for PDU session establishment are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

In the illustrated embodiment, the user equipment initiates the PDU session modification procedure by transmitting an NAS message <NUM> to the AMF. However, in other embodiments, the SMF or a RAN initiate the PDU session modification procedure. The AMF sends a notification <NUM> of the request to the SMF. The PCF performs a PCF initiated policy association modification procedure to notify the SMS about the modification of policies, as indicated by the double-headed arrows <NUM>.

If the SMF requested the modification, the UDM sends a message <NUM> to update subscription information that the SMF, which updates the subscription information and sends an acknowledgment <NUM> back to the UDM. The SMF also performs a QoS update four the PDU session at block <NUM>.

The SMF may need to report some subscribed events to the PCF by performing an SMF initiated policy association modification procedure, as indicated by the double-headed arrows <NUM>. However, this step may be skipped in some cases.

The SMF responds to the AMF by sending a context message <NUM>. For an SMF requested modification, the SMF transmits a message <NUM> to the AMF to indicate, among other things, and allowed Access type. In some embodiments, the SMF invokes Namf_Communication _N1N2MessageTransfer (N2 SM information (PDU Session ID, QFI(s), QoS Profile(s), Session-AMBR), N1 SM container (PDU Session Modification Command (PDU Session ID, QoS rule(s), QoS Flow level QoS parameters if needed for the QoS Flow(s) associated with the QoS rule(s), QoS rule operation and QoS Flow level QoS parameters operation, Session-AMBR)), Allowed Access Type). In response to the message <NUM>, the AMF transmits an acknowledgment message <NUM> to the SMF.

The AMF transmits a session request message <NUM> to the RAN, which performs access network specific resource modification including sending PDU session modification commands and acknowledgments, as indicated by the double-headed arrow <NUM>. The remaining PDU session modification procedure is performed at block <NUM>.

<FIG> is a message flow <NUM> for mobile-originated short message service (SMS) signaling over NAS in CM-idle mode according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for the SMS service are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

The user equipment performs domain selection for the SMS originated at the user equipment, as indicated by the double-headed arrows <NUM>. The user equipment and generates and sends an SMS message <NUM> to the AMF. The SMS message <NUM> is encapsulated in an NAS message with an indication indicating that the NAS messages for SMS transporting.

The AMF forwards (at step <NUM>) the SMS message to an SMSF that is serving the user equipment. The SMSF responds with an acknowledgment <NUM> including information indicating the allowed Access types for the SMS message. In some embodiments, the SMSF invokes Namf_Communication_N1N2MessageTransfer service operation to forward SMS ack message to AMF. Allowed Access Type is set to "both," to indicate that the SMS message is transmittable using 3GPP access or non-3GPP access. The AMF forwards (at step <NUM>) the SMS acknowledgment message from the SMS to the user equipment using a downlink unit data message.

The SMSF performs a message exchange <NUM>, <NUM>, <NUM> to check SMS management subscription data. The SMSF forwards a submit report <NUM> to the AMF, which then forwards (at <NUM>) the submit report to the user equipment via downlink NAS transport. In response to determining that no more SMS messages are to be sent, the user equipment returns an acknowledgment <NUM>, which the AMF forwards (at step <NUM>) to the SMS.

<FIG> is a message flow <NUM> for mobile-terminated short message service (SMS) signaling over NAS in CM-idle mode via 3GPP access according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for the SMS service are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure4. <NUM>-<NUM> of 3GPP TS <NUM> v15.

A service center (SC) transfers a message <NUM> to an SMS gateway mobile services switching center (GMSC). Routing information for the message is negotiated between the SMS and the UDM, as indicated by the double-headed arrow <NUM>, and then the SMS-GMSC forwards the mobile terminated SMS message <NUM> to the SMSF.

The SMSF checks the SMS management subscription data to determine whether SMS delivery is allowed using the message exchange <NUM>, <NUM>, <NUM>.

The SMSF sends the SMS message <NUM> to the AMF, which forwards the SMS message body <NUM> to the user equipment. In some embodiments, the SMSF forwards the SMS message to be sent as defined in TS <NUM>. The SMS message consists of CP-DATA/RP-DATA/TPDU/SMS-DELIVER parts, which is sent to AMF by invoking Namf_Communication _N1N2MessageTransfer service operation. The Allowed Access Type is set to "both," to indicate that the SMS message is transmittable using either a 3GPP access or non-3GPP access. The AMF transfers the SMS message to the user equipment.

The user equipment acknowledges receipt to the AMF and the SMSF by sending the acknowledgment messages <NUM>, <NUM>. The user equipment also returns a delivery report using the messages <NUM>, <NUM>. The delivery report is encapsulated in an NAS message and sent to the AMF, which forwards the message to the SMSF.

The SMS acknowledges receipt of the delivery report to the UE using the messages <NUM>, <NUM>. In some embodiments, the SMSF acknowledges receipt of the delivery report to the UE. The SMSF uses Namf_Communication_N1N2MessageTransfer service operation to send SMS CP ack message to the AMF. The AMF encapsulates the SMS message via a NAS message to the UE. If SMSF has more than one SMS to send, the SMSF and the AMF forwards subsequent SMS /SMS ack/ delivery report the same way as described above. The Allowed Access Type is set to "both," to indicate allowable delivery via 3GPP access or non-3GPP access.

Concurrently with transmission of the messages <NUM>, <NUM>, the SMSF delivers the delivery report to the SC using the messages <NUM>, <NUM>.

In some embodiments, mobile terminated SMS in CM-CONNECTED procedure is specified by reusing the MT SMS in CM-IDLE state with the following modification:.

In some embodiments, mobile terminated SMS procedure via non-3GPP access is specified by reusing the MT SMS via 3GPP access in CM-CONNECTED state with the following modification:.

<FIG> is a message flow <NUM> for the user equipment assisted and user equipment-based positioning procedure according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for the positioning procedure are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

An LMF invokes a positioning service operation by transmitting a message <NUM> to the AMF. In some embodiments, the LMF invokes the Namf Communication _N1N2MessageTransfer service operation towards the AMF to request the transfer of a Downlink (DL) Positioning message to the user equipment. The service operation includes the DL Positioning message. The Session ID parameter of the Namf_Communication _N1N2MessageTransfer service operation is set to the LCS Correlation identifier. The Downlink Positioning message may request location information from the UE, provide assistance data to the UE or query for the UE capabilities. The Allowed Access Type is set to "3GPP," to indicate that the positioning services only provided via 3GPP access and is not provided via non-3GPP access.

If the user equipment is in a CM-idle state, the AMF initiates a network triggered service request procedure <NUM>. The AMF forwards a downlink positioning message <NUM> to the user equipment. The user equipment stores (at block <NUM>) any assistance data provided in the downlink positioning message. The user equipment also performs any positioning measurements and location computations requested in the downlink positioning message <NUM>. If the user equipment entered the CM-idle state in block <NUM>, the user equipment instigates a user equipment triggered service request at block <NUM>.

The user equipment returns location information obtained at block <NUM> by transmitting a message <NUM> to the AMF. The AMF then invokes a notification service operation <NUM> towards the LMF.

<FIG> is a message flow <NUM> for a network assisted positioning procedure according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for the network assisted positioning procedure are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

The LMF transmits a network positioning message <NUM> to the AMF. In some embodiments, the LMF invokes the Namf_Communication _N1N2MessageTransfer service operation towards the AMF to request the transfer of a Network Positioning message to the serving NG-RAN node (gNB or ng-eNB) for the UE. The service operation includes the Network Positioning message and the LCS Correlation identifier. The Network Positioning message may request location information for the UE from the NG-RAN. The Allowed Access Type is set to "3GPP," to indicate that the positioning services only provided via 3GPP access and is not provided via non-3GPP access.

If the user equipment is in a CM-idle state, the AMF initiates a network triggered service request procedure <NUM>. The AMF forwards a network positioning message <NUM> to a serving RAN node, which obtains location information, e.g., by performing measurements, at the block <NUM>. In the obtains location information is transmitted from the RAN to the AMF in a transport message <NUM>. The AMF then forwards the location information to the LMF using a service notification <NUM>.

<FIG> is a message flow <NUM> for obtaining network assistance data according to some embodiments. The message flow <NUM> is implemented in some embodiments of the communication system <NUM> shown in <FIG>. In the interest of clarity, some of the messages used for the network assistance procedure are not illustrated in <FIG>. A more detailed description including the omitted messages is found in specified in §<NUM>. <NUM> and Figure <NUM>. <NUM>-<NUM> of 3GPP TS <NUM> v15.

The LMF initiates a transfer service operation by sending a network positioning message <NUM> to the AMF. In some embodiments, the LMF invokes the Namf_Communication_N1N2MessageTransfer service operation towards the AMF to request the transfer of a Network Positioning message to a NG-RAN node (gNB or ng-eNB) in the NG-RAN. The service operation includes the Network Positioning message and the target NG-RAN node identity. The Network Positioning message may request position related information from the NG-RAN. The Allowed Access Type is set to "3GPP," to indicate that network positioning is performed only via 3GPP access and is not performed using non-3GPP access.

The AMF forwards (at step <NUM>) the network positioning message to a target RAN node indicated in the message <NUM> received from the LMF. The target RAN mode obtains any requested position related information, e.g., by performing measurements at block <NUM>. The target ran node returns any position related information to the AMF in a network positioning message included in a transport message <NUM>. The AMF forwards information from the message <NUM> to the LMF in a notification <NUM>.

In some embodiments, a message transfer service operation is defined according to the following parameters:.

If the UE is in CM-IDLE state, the AMF initiates the network triggered service request procedure as specified in clause <NUM>. <NUM> of TS <NUM> and responds to the consumer NF with a result indication, "attempting to reach UE". Otherwise, the AMF responds to the consumer NF, with a Namf_Communication _N1N2MessageTransfer response, providing a result indication of whether the AMF was able to successfully transfer the N1 and/or the N2 message towards the UE and/or the AN. A result indication of "N1/N2 transfer success" does not mean that N1 message is successfully received by the UE. It only means that the AMF is able to successfully send the N1 or N2 message towards the AN.

The "Allowed Access Type" indicates which access type can be used to send the N1 or N2 message towards the AN. If the Allowed Access Type is set to either 3GPP or non-3GPP, the indicated access type shall be used. If the Allowed Access Type is set to "both", the AN shall send the N1 or N2 message via 3GPP if the UE is registered to 3GPP access first and non-3GPP access as fallback or, if the UE is not registered to 3GPP access, the AN shall send the N1 or N2 message via non-3GPP (if in CM-CONNECTED state).

The "Area of validity for the N2 SM information", if included is used by the AMF to determine whether the N2 SM information provided by the consumer NF can be used towards the AN based on the current location of the UE. If the location of the UE is outside the "Area of validity for the N2 SM information" indicated, the AMF shall not send the N2 SM information to the AN.

In case the consumer NF knows that a specific downlink N1 message is the last message to be transferred in this transaction, the consumer NF shall include the last message indication in the Namf_Communication_N1N2MessageTransfer service operation so that the AMF knows that the no more downlink N1 message need to be transferred for this transaction.

The CN NF is implicitly subscribed to be notified of N1N2TransferFailure by providing the N1N2TransferFailure Notification Target Address. When AMF detects that the UE fails to response to paging, the AMF invokes the Namf_Communication_N1N2TransferFailureNotification to provide the failure notification to the location addressed by N1N2TransferFailure Notification Target Address.

If the result of the service operation fails, the AMF shall set the corresponding cause value in the result indication which can be used by the NF consumer for further action. In case the related UE is not served by AMF and the AMF knows which AMF is serving the UE, the AMF provides redirection information which can be used by the consumer NF to resend UE related message to the AMF that serves the UE.

As discussed herein, when the user equipment is involved in a handover between non-3GPP and 3GPP accesses, the user equipment initiates PDU session establishment. In this case, the SMF requests PCF to update the PDU session related policies all along the path. This is described in step <NUM> of figure <NUM>. <NUM>-<NUM> of TS <NUM>, which states: "the SMF may perform an SMF initiated SM Policy Association Modification procedure to provide information on the Policy Control Request Trigger condition(s) that have been met. " However, in the case of a Service Request initiated by a user equipment (due to paging), in which the list of "PDU sessions allowed to be moved to 3GPP access" is included, the Core Network may decide to move one or several PDU sessions from non-3GPP to 3GPP access. In that case, the SMF should ask PCF about whether new PDU session related policies should apply. But this is not described in the specifications.

If the AMF has received a N1 SM Container and N2 SM Information from the SMF and the PDU Session ID is associated to an access over which the user equipment cannot be reached, the AMF shall notify/page the UE via the "other access". The user equipment replies with Service Request and, if the PDU session is in the returned list of allowed PDU sessions, the AMF should indicate that the access type has changed in the notification to SMF and discard the N1 SM Container and the N2 SM Information. The SMF is then able to request PCF about the PCC rules in the other access and build a new N1 SM Container, adapted to the new access. This solution works but it increases the signaling between SMF and AMF: if the SMF is aware that the N1 SM Container and the N2 SM Information are valid in any access, then it could tell it to the AMF. This could be done by the SMF indicating the access allowed to be used for sending the signaling (3GPP, non-3GPP, both).

Moreover, the SMSF and the LMF use the same service operation as the SMF i.e. Namf_Communication_N1N2MessageTransfer. It should be possible for the SMSF or the LMF to specify whether the N1 message should be sent via 3GPP access, non-3GPP access or any of them. Indeed, there is a need to have different behaviors depending on the use case. For example, the SMS could be sent over any access (attempting over 3GPP access and if no answer attempting over non-3GPP access). However, a Downlink Positioning message from LMF (see clause <NUM>. <NUM> of TS23. <NUM>) should be dedicated to the 3GPP access only. How could the AMF know whether to send the N1 SM message over 3GPP access, non-3GPP access or both?.

The AMF should not decide different behaviors depending on the source (SMF, SMSF, LMF, etc). If a new NF wants to use the.

Namf_Communication _N1N2MessageTransfer service operation, the AMF should know whether the service applies for a particular access or not.

Some embodiments of the techniques disclosed herein are applied to the case in which a PDU session is moved from non-3GPP access to 3GPP access using a user equipment triggered Service request. The Namf_Communication_N1N2MessageTransfer service operation is enhanced with a new input "Allowed Access Type" stating whether the service applies for 3GPP access, non-3GPP access or both (always trying 3GPP access first). It is clarified that the N1 SM Container shall be sent using the Dowlink NAS Transport (and not the Service Accept), as described in 3GPP TS <NUM>, (see clauses <NUM>. <NUM> and <NUM>. <NUM>) and in TS <NUM> clause <NUM>. <NUM> for SMS, clause <NUM>. <NUM> for Location Services.

Such storage media can include, but is not limited to, optical media (e.g., compact disc (CD), digital versatile disc (DVD), Blu-Ray disc), magnetic media (e.g., floppy disc , magnetic tape, or magnetic hard drive), volatile memory (e.g., random access memory (RAM) or cache), non-volatile memory (e.g., read-only memory (ROM) or Flash memory), or microelectromechanical systems (MEMS)-based storage media.

Claim 1:
A method comprising:
receiving (<NUM>), at a service responsible for sending signaling to a user equipment or an access network serving the user equipment, a request to send the signaling to the user equipment or to the access network together with access type control information indicating whether the signaling is transmittable using any of a plurality of access types or a specific access type provided in the request; and
selectively forwarding from the service the signaling to the user equipment or the access network based on the access type control information,
wherein the selectively forwarding is characterised by: rejecting (<NUM>) by the service the request when it is not possible to send the signaling via the specific access type provided in the request;
wherein the service detects (<NUM>) that it is not possible to send the signaling via the specific access type provided in the request when the service detects at least one of following:
the user equipment is not in a connected state via the specific access type and either the user equipment cannot be paged via the specific access type or the user equipment does not answer to paging over the specific access type, or
the user equipment is in the connected state via the specific access type and the access network indicates a failure of access network paging.