ACCESS CONTROL FOR USER EQUIPMENT IN A CONNECTED MODE

Abstract

A user device operating in connected mode includes a first layer, a second layer, and a third layer. The first layer generates a request to send a non-initial No Access Layer (NAS) message across a first connection operating according to a first Radio Access Technology (RAT). The second layer determines whether access to the first connection is blocked for the non-initial NAS message. The first layer selects a connection to deliver the non-initial NAS message between the first connection and a second connection operating according to a second RAT in response to the blocked access to the first connection. In some cases, the non-initial NAS message is a Short Message Service (SMS) message from a mobile source or an uplink NAS transport message. In some cases, the first layer is a NAS layer and the second layer is a Radio Resource Control layer.

Description

Wireless communication systems include a network of base stations (also known as radio access networks, gNodeB, eNodeB, or access points) that provide wireless connectivity to one or more user devices within their respective geographic areas or cells. To conserve battery power, a user device can operate in an idle mode that consumes less power but prevents it from transmitting uplink data to a core network. The user device must transmit an access attempt to the base station to acquire a radio connection and enter connected mode, which then allows it to transmit uplink data. The base station and / or the core network can become overloaded if too many user devices use or attempt to use network resources.Therefore, some access attempts by idle user equipment are blocked (i.e., prevented or prohibited) to reduce or limit resource consumption by the user equipment. For example, a network operating according to Fourth Generation (4G) standards defined by the Third Generation Partnership Project (3GPP), such as Long-Term Evolution (LTE) standards, imposes access restrictions on idle user equipment to prevent it from registering with or establishing a Radio Resource Control (RRC) connection to the network. Access blocking is typically achieved by transmitting a blocking configuration to the user equipment so that the user equipment can determine when an access attempt is blocked. BRIEF DESCRIPTION OF THE FIGURES The present description, and its numerous features and advantages, can be better understood by those skilled in the art with reference to the accompanying figures. The use of the same reference symbols in different figures indicates similar or identical elements. FIG. 1 is a block diagram of a communication system that supports access control and selective use of 3GPP and non-3GPP connections for access attempts according to some modalities. FIG. 2 is a block diagram of a network functions virtualization (NFV) architecture according to some modalities. FIG. 3 is a message flow for making an access request for an initial non-access stratum (NAS) message according to some modalities. FIG. 4 is a message flow for selectively performing an access request for a non-initial NAS message using a 3GPP or non-3GPP connection depending on some modalities. ηαίηηη / ίζηζ / Ε / γι FIG. 5 is a block diagram of a user equipment that supports network access through 3GPP and non-3GPP connections according to some modes. Figure 6 is a block diagram of a communication system according to several modes. DETAILED DESCRIPTION The fifth-generation (5G) standards defined by 3GPP are designed to alleviate the global bandwidth shortage by supporting wireless communication at frequencies above 6 gigahertz (GHz), such as in the millimeter-wave frequency range between 30 and 300 GHz. 5G standards enforce access restrictions on user equipment in idle, connected-active, and connected-idle modes.Therefore, access blocking applies not only to initial non-access stratum (NAS) messages, such as registration requests, deregistration requests, and service requests transmitted by user equipment in idle mode, but also to non-initial NAS messages, such as requests to transmit Short Message Service (SMS) messages over NAS, uplink NAS transport messages to establish Packet Unit (PDU) sessions, and uplink NAS transport messages to request modification of a PDU session transmitted by user equipment in connected mode. However, current 5G standards do not define how to handle the case when an access attempt triggered by a non-initial NAS message is blocked. Some user equipment modes support simultaneous 3GPP and non-3GPP connections.Therefore, 5G standards allow a mobile-source SMS message over NAS to be delivered from the user equipment via either 3GPP or non-3GPP access, such as a Wi-Fi hotspot connection. However, if a lower 3GPP access layer on the user equipment (e.g., an access stratum, AS, a layer below the NAS layer) blocks an access attempt, such as a request to transmit a mobile-source SMS message over a 3GPP connection, the connected user equipment cannot use the non-3GPP connection. A user device is prohibited from sending a non-initial non-access stratum (NAS) message (for example, an uplink NAS transport message) using a 3GPP connection if the user device's Radio Resource Control (RRC) layer indicates that the access attempt is blocked. The non-initial NAS message is subsequently sent over the 3GPP connection, if still required, when the RRC layer indicates that the block has been eased for the access category with which the access attempt was associated. However, if the user device supports both a 3GPP and a non-3GPP connection, the user device may selectively request the transmission of a mobile-source message over either the 3GPP or non-3GPP connection while the user device is in connected mode.The selection of a 3GPP or non-3GPP connection for transmitting a mobile-source message depends on whether the request is blocked at the user equipment's RRC layer. For example, a NAS layer on the user equipment might transmit a query specifying a category or identity for an access request to the RRC layer, which returns a result indicating whether the access category or identity is blocked. The user equipment transmits the request over the non-3GPP connection, if available, if the request is blocked at the RRC layer, and over the 3GPP connection if the request is not blocked. In some modes, selective requests for transmission of the mobile source message are made for one or more predefined access categories or identities. For example, the user equipment might selectively request transmission of a Short Message Service (SMS) message via a Non-Access Layer (NAS) message, an uplink NAS transport message to establish a Data Packet Unit (PD1) session, or an uplink NAS transport message to request modification of a PDU session, depending on whether messages in these access categories are blocked. Access attempts associated with an access category that is blocked on the user equipment must cease until the RRC layer indicates that the access block has been lifted for the corresponding access category.Once the access block has been relieved, the user equipment initiates a transport procedure over the 3GPP connection, if still necessary. Figure 1 is a block diagram of a communication system that supports access control and the selective use of 3GPP and non-3GPP connections for access attempts under certain modalities. As used herein, a 3GPP connection refers to a connection that operates in accordance with standards established by 3GPP, such as 5G or LTE standards. Therefore, a 3GPP connection is a connection that operates under a first Radio Access Technology (RAT). As used herein, a non-3GPP connection refers to a connection that operates under standards other than 3GPP, such as Wi-Fi standards for wireless access in an unlicensed frequency band. Therefore, a non-3GPP connection is a connection that operates under a second RAT that differs from the first RAT.Some modes of the 100 communication system implement a different first and second RAT, although the techniques described herein are described in the context of 3GPP and non-3GPP connections for the sake of clarity. ηαίηηη / ίζηζ / Ε / γι The 100 communication system provides support for both mobile and fixed access. As used herein, the term mobile access refers to accessing a communication system (e.g., the 100 communication system) via an air interface. Therefore, mobile access may be referred to as wireless access, mobile communication, wireless communication, or other similar terms. The term fixed access refers to accessing a communication system using a device that is physically connected to the communication system, for example, accessing a communication system such as the 100 communication system via cables, fiber optics, and the like. Therefore, fixed access may be referred to as wired access, wired communication, or other similar terms. In some configurations, the final segment of a fixed access connection may be provided by a wireless access point, such as a Wi-Fi access point.The 100 communication system supports hybrid access, which allows devices to simultaneously access the 100 communication system using mobile access and fixed access. The communication system 100 includes a core network 105 that is accessible by 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. As used herein, the term user plane refers to a part of a routing architecture that performs routing of packets arriving at an input interface. For example, the user plane can be implemented using routing tables to determine a path from the input interface through a forwarding structure to the appropriate output interface. The user plane may also be referred to as the data plane or forwarding plane. As used herein, the term control plane refers to a part of the routing architecture that defines a network topology.For example, the control plane can be used to configure the routing tables used to forward packets in the user plane. Control plane logic can also be used to set packet priority or quality of service, or to identify packets that should be dropped. The core network 105 includes an Access and Mobility Management (AMF) function 110 that manages access control and mobility for devices in the communication system 100. The core network 105 also includes a Session Management Function (SMF) 115 to configure and manage sessions in the communication system 100 according to network policies. An association between the user equipment and the core network 105 can be represented as a Protocol Data Unit (PDU) session that can be managed by the SMF 115. The PDU session supports data connectivity between the user equipment and a data network. The core network 105 also includes a Policy Control Function (PCF) 120 that stores policies for the user equipment that is connected to the core network 105.Therefore, the information stored in PCF 120 is used to apply policies to actions associated with the user equipment, such as mobility restrictions within the communication system 100. The core network 105 also includes a unified data manager (UDM) 125 that processes credentials, location management, subscription management, and the like. The UDM 125 stores data that includes user subscription data, such as subscription identifiers, security credentials, access and mobility-related subscription data, and session-related subscription data. The core network 105 further includes one or more user plane functions (UPFs) 130 that can be deployed in the communication system 100 to provide services to users of the communication system 100. The user plane function 130 can operate as an endpoint for service flows used for packet broadcast, multicast, or unicast, as described herein.Therefore, user plane function 130 can store endpoint identifiers for service flows. User plane function 130 is connected to a data network 135. The entities within the 105 core network are connected by various interfaces implemented according to standards such as the 5G network architecture. Some modalities of the 105 core network include additional functionality, such as an authentication function and a network function repository, which are not shown in Figure 1 for clarity. Some modalities of the 105 core network are implemented using network function virtualization and software-defined networking, as described herein. For example, different network segments can be used to instantiate different instances of AMF 110, SMF 115, UPF 130, or UDM 125 for different users or devices. Each protocol data unit (PDU) session is part of a network segment. The core network 105 provides network access to user equipment 140 via mobile access. For example, user equipment 140 can access the core network 105 through a base station 145 (or radio access network) that is connected to AMF 110 via a corresponding interface such as an N2 interface. Base station 145 is also connected to UPF 120 via a corresponding interface such as an N3 interface, which is not shown in FIG. 1 for clarity. Some configurations of base station 145 are implemented as a 5G gigabit NodeB (gNB) in accordance with the 5G standards defined by 3GPP. 105 also provides network access to user equipment 140 via a fixed access connection. For example, user equipment 140 can establish a connection to a residential gateway 150, which has a wired connection to an Ethernet network 155. In the illustrated mode, a final segment of the fixed access connection between user equipment 140 and the core network 105 is implemented using wireless access technology. For example, a Wi-Fi access point 160 can be used to provide the final segment of the fixed access connection. However, in other cases, user equipment 140 connects to the residential gateway 150 using a wired connection. Some wired connection modes utilize line termination devices such as a digital subscriber line access multiplexer (DSLAM) or a gigabit passive optical network (GPON). Interworking Function 165 is provided between Ethernet Network 155 and Core Network 105. Interworking Function 165 may also be referred to as Non-3GPP Interconnection Function (N3IWF). Interworking Function 165 is configured to modify or translate messages transmitted from the fixed-access user equipment to Core Network 105 so that the fixed-access user equipment appears to be accessing Core Network 105 in accordance with mobile access standards or protocols from the perspective of Core Network 105. Interworking Function 165 is also configured to modify or translate messages carried from Core Network 105 to the fixed-access user equipment so that the messages received by the fixed-access user equipment conform to the corresponding fixed-access standards or protocols. Interworking Function 165 supports interfaces with AMF 110 and UPF 130. User Equipment 140 operates in either idle mode or one of two connected modes: idle connected mode and active connected mode. In idle mode, User Equipment 140 can select a public land mobile network (PLMN), receive broadcast system information, perform cell reselection mobility, and receive paging messages to inform User Equipment 140 of mobile-terminated data availability. Idle User Equipment 140 does not transmit uplink data to the core network 105. Idle User Equipment 140 must switch to one of the connected modes to receive downlink data or transmit uplink data.In connected-inactive mode, user equipment 140 receives information from the broadcast system, performs cell reselection mobility, receives paging messages initiated by a radio access network, maintains user plane and control plane connections with the core network 105, and has a context stored in the radio access network and user equipment 140. In connected-active mode, user equipment 140 maintains user plane and control plane connections with the core network 105 and has a corresponding context stored in the radio access network and user equipment 140. The radio access network knows the identity of a cell that includes user equipment 140. Unicast data can be transferred to and from user equipment 140 in connected-active mode.The network can also monitor the mobility of user equipment 140, for example, based on measurements made by user equipment 140. Some configurations of user equipment 140 implement multiple transmitters, receivers, or transceivers that operate according to different RATs. For example, user equipment 140 uses a primary transceiver that operates according to the 5G standards defined by 3GPP and a secondary transceiver that operates according to non-3GPP standards, such as Wi-Fi, for communications in an unlicensed frequency band. Therefore, user equipment 140 can maintain separate, and in some cases simultaneous, connections operating according to different RATs, such as a 5G connection to base station 145 and a Wi-Fi connection to access point 160. If user equipment 140 is in idle mode, it can transmit an access request to initiate a communication session with the core network 105. For example, the access request can be transmitted as a non-access stratum (NAS) initial message. If the access request is accepted, a connection is established between user equipment 140 and the core network 105, at which point user equipment 140 enters a connected mode. Idle user equipment 140 also transmits other initial NAS messages, such as deregistration requests and service requests. User equipment 140 transmits non-initial access requests when it is operating in one of the connected modes.Non-initial NAS requests include requests to transmit Short Message Service (SMS) messages over NAS, uplink NAS transport messages to establish Packet Data Unit (PDU) sessions, and uplink NAS transport messages to request modification of a PDU session that are transmitted by the user equipment in connected mode. As discussed in detail herein, user equipment 140 may determine that non-initial NAS requests are blocked, so user equipment 140 does not transmit the non-initial NAS request over connection 170 to base station 145. In some cases, user equipment 140 transmits a request to send the non-initial NAS message over connection 175 to access point 160 in response to the determination that the attempt to transmit the request to base station 145 is blocked. For example, user equipment 140 ceases the request over connection 170 in response to the blocking of access requests. User equipment 140 remains in the current cell and applies a cell reselection process in response to the blocked access to the first connection.User 140 can then transmit the request using connection 175 in response to accessing connection 170, which is blocked. Alternatively, user 140 transmits the request after ceasing to do so in response to the blocking being eased, if the request is still needed. Figure 2 is a block diagram of an NFV 200 architecture according to some modalities. The NFV 200 architecture is used to implement some modalities of the communication system 100 shown in Figure 1. For example, instances of AMF 110, SMF 115, PCF 120, and UDM 125 can be instantiated as virtual functions in the NFV 200 architecture. The NFV 200 architecture includes hardware resources 201, which include compute hardware 202, storage hardware 203, and network hardware 204. Compute hardware 202 is implemented using one or more processors, storage hardware 203 is implemented using one or more memories, and network hardware 204 is implemented using one or more transceivers, transmitters, receivers, interfaces, and the like. A virtualization layer (205) provides an abstract representation of hardware resources (201). The abstract representation supported by the virtualization layer (205) can be managed using a virtualized infrastructure manager (210), which is part of the management and orchestration (M&O) module of NFV (215). Some modes of the manager (210) are configured to collect and send performance measurements and events that may occur in the NFV architecture (200). For example, performance measurements can be sent to an orchestrator (ORCH) (217) deployed in the NFV M&O (215). Hardware resources (201) and the virtualization layer (205) can be used to implement virtual resources (220), including compute virtual resources (221), storage virtual resources (222), and networking virtual resources (223). Virtual network functions (VNF1, VNF2, VNF3) run on top of the NFV infrastructure (e.g., hardware resources 201) and utilize virtual resources 220. For example, virtual network functions (VNF1, VNF2, VNF3) can be implemented using virtual machines supported by virtual compute resources 221, virtual memory supported by virtual storage resources 222, or virtual networks supported by virtual networking resources 223. Element management systems (EMS1, EMS2, EMS3) are responsible for managing virtual network functions (VNF1, VNF2, VNF3). For example, element management systems (EMS1, EMS2, EMS3) can be responsible for fault and performance management.In some modalities, each of the virtual network functions (VNF1, VNF2, VNF3) is controlled by a corresponding VNF manager 225 who exchanges information and coordinates actions with the manager 210 or the orchestrator 217. The NFV 200 architecture may include an Operational Support System (OSS) / Business Support System (BSS) 230. The OSS / BSS 230 handles network management, including fault management through OSS functionality. The OSS / BSS 230 also handles customer and product management using BSS functionality. Some NFV 200 architecture models use a set of descriptors 235 to store descriptions of services, virtual network functions, or infrastructure compatible with the NFV 200 architecture. The information in the descriptors 235 can be updated or modified by the NFV 215 M&O. The NFV 200 architecture implements network segments that provide control plane or user plane functions, such as AMF 110, SMF 115, AUSF 120, and UDM 125 instances, as shown in Figure 1. A network segment is a complete logical network that provides communication services and network capabilities, which can vary from segment to segment. User equipment can simultaneously access multiple segments that support multiple service flows between a core network and the user equipment. Some user equipment models provide Network Segment Selection Assistance Information (NSSAI) parameters to the network to assist in selecting a segment instance for the user equipment. A single NSSAI can result in the selection of multiple segments.The NFV 200 architecture can also use device capabilities, subscription information, and local carrier policies for selection. An NSSAI is a collection of smaller components, individual NSSAIs (S-NSSAIs), each of which includes a Segment Service Type (SST) and possibly a Segment Differentiator (SD). The Segment Service Type refers to expected network behavior in terms of features and services (e.g., specialized for broadband or massive IoT), while the Segment Differentiator can help select among various network segment instances of the same type, for example, to isolate traffic related to different services on different segments. Figure 3 shows a 300 message flow for making an access request for an initial NAS message under certain modes. The 300 message flow is implemented in some modes of the 140 user equipment shown in Figure 1. The user equipment includes a session management layer (5GSM), a mobility management layer (5GMM), and a radio resource control (RRC) layer. The session management layer is referred to as the upper layer, and the RRC layer is referred to as the lower layer. The session management layer transmits a 305 request to send an initial uplink NAS transport message to establish or modify a PDU session. In response to receiving the 305 request, the mobility management layer sends a 310 message indicating an access category or access identity (or identities) for the 305 request. The 310 message, which includes the request and the access category or identity, is transmitted to the lower RRC layer, which determines whether the access request is blocked. The RRC layer returns a 315 message indicating the blocking result, for example, blocked or unblocked. Examples of techniques are described for determining whether an access request in an access category or having an access identity (or identities) is blocked in NETWORK SLICES-SPECIFIC ACCESS BARRING FOR WIRELESS NETWORKS (NETWORK SLICES-SPECIFIC ACCESS BARRING FOR WIRELESS NETWORKS), n.Serial No. 62 / 544 519, submitted on August 11, 2017, which is incorporated herein by reference in its entirety. Examples of unified access control techniques are described in 3GPP Technical Specification 24.501, which is incorporated herein by reference in its entirety. The user computer determines (in 320) whether to initiate the mobile-start NAS transport procedure based on the information returned in message 315. If message 315 indicates that the access request is blocked, the user computer does not initiate the mobile-start NAS transport procedure. The user computer remains in its current service cell and applies a normal cell reselection process. In some cases, the RRC layer subsequently returns another message (not shown in FIG. 3) indicating that the block has been relieved and the access request is no longer blocked. For example, the RRC layer might return a message to the mobility management layer indicating that the block has been relieved for an access category or access identifier associated with the previously blocked access attempt.If still necessary, the mobile-start NAS transport procedure is initiated in response to receiving the message indicating that the lock has been removed. Figure 4 shows a 400 message flow for selectively performing an access request for a non-initial NAS message using a 3GPP or non-3GPP connection, depending on the configuration. The 400 message flow is implemented in some configurations of the 140 user equipment shown in Figure 1. The user equipment includes an SMS layer (SMS), a mobility management layer (5GMM), and a radio resource control (RRC) layer. The session management layer is referred to as the upper layer, and the RRC layer as the lower layer. The user equipment is operating in connected mode. Some configurations of the user equipment operate in connected-inactive mode or connected-active mode.The user equipment implements several sets of transmitters, receivers, or transceivers to support communication over a 3GPP connection, for example, in accordance with 5G standards, and over a non-3GPP connection, such as a Wi-Fi connection in an unlicensed frequency band. In the illustrated mode, the user equipment is registered to access a data network over both the 3GPP and non-3GPP connections. The SMS layer of the connected user equipment transmits a 405 request to send a non-initial uplink NAS transport message using the 3GPP connection. In the illustrated mode, the SMS layer transmits the 405 request to send an SMS message originating from the mobile device over NAS. Some SMS layer modes are also configured to transmit requests for other non-initial uplink NAS transport messages, including an uplink NAS transport message to establish a PDU session, an uplink NAS transport message to request a modification of a PDU session, and so on. In response to receiving a 405 request, the mobility management layer sends a 410 message indicating an access category or access identity (or identities) for the 405 request. The 410 message is transmitted to the lower RRC layer, which determines whether the access request for the 3GPP connection is blocked. The RRC layer returns a 415 message indicating the blocking result, for example, blocked or unblocked. The mobility management layer then selects a connection to deliver the non-initial uplink NAS transport message. Some mobility management layer modes select between the 3GPP connection and the non-3GPP connection in response to the blocked access to the first connection. The user equipment determines (in block 420) whether to transmit the request to send the SMS message over NAS (or another non-initial uplink NAS transport message) using the 3GPP connection based on the information returned in message 415. If message 415 indicates that the access request is blocked, the mobility management layer on the user equipment does not select the 3GPP connection. The user equipment does not initiate the mobile-start NAS transport procedure to begin an access attempt for the 3GPP connection. The user equipment remains in its current service cell and applies a normal cell reselection process. Since the user device is registered to communicate with the data network over a non-3GPP connection, such as Wi-Fi, the user device determines whether the non-3GPP nQLnnn / Lznz / E / Yii connection is available. If so, the mobility management layer determines (in block 425) that the user device can transmit the SMS message over NAS (or another non-initial uplink NAS transport message) over the non-3GPP connection. Therefore, the mobility management layer on the user device selects the non-3GPP connection and transmits a 430 request to a non-3GPP access layer (Wi-Fi) implemented on the user device. Request 430 is to send the SMS message via NAS (or other non-initial uplink NAS transport message) using the non-3GPP connection available to the user equipment. The non-3GPP connection is not always available to the user equipment, and therefore the user equipment cannot always send the SMS message via NAS (or another non-initial uplink NAS transport message) over the non-3GPP connection. In that case, the user equipment continues to refrain from making an access attempt due to the block. If the RRC layer subsequently returns another message (not shown in FIG. 4) indicating that the block has been relieved and the access request is no longer blocked for the access category or access identifier associated with the previously blocked access attempt, the mobile-initial NAS transport procedure is initiated (at block 435) in response to receiving the message indicating that the block has been relieved. Figure 5 is a block diagram of a User Equipment 500 that supports network access via 3GPP and non-3GPP connections, depending on the mode. User Equipment 500 is used to implement some modes of User Equipment 140, shown in Figure 1. It is configured to implement some modes of Message Flow 300, shown in Figure 3, and Message Flow 400, shown in Figure 4. User Equipment 500 includes an SMS Layer 505 that generates requests to send SMS messages via NAS. Some modes of SMS Layer 505 also generate requests for other non-initial uplink NAS messages, including an uplink NAS transport message to establish a PDU session, an uplink NAS transport message to request a PDU session modification, and similar messages.The 500 user device can also implement other layers (not shown in FIG. 5) such as a session management layer that generates initial uplink NAS messages. The 500 user device includes a 510 session management layer that is configured to send an initial uplink NAS transport message in order to establish or modify a PDU session. A mobility management layer 515 on the user equipment 500 is configured to determine an access blocking status in response to receiving requests from the SMS layer 505 or the session management layer 510. Some modes of the mobility management layer 515, also called the NAS layer, generate messages indicating an access category or access identity (or identities) for the request. The mobility management layer 515 forwards the request to an RRC layer 520, which determines whether the access request is blocked for the 3GPP connection. The RRC layer 520 returns messages to the mobility management layer 515 indicating the blocking results, for example, blocked or not blocked. The User Equipment 500 also includes a non-3GPP access layer 525 to support communication over a non-3GPP connection, such as Wi-Fi. In response to the RRC layer 520 returning a message indicating that the access request is blocked for the 3GPP connection, the Mobility Management Layer 515 forwards requests to the non-3GPP access layer 525 to send non-initial uplink NAS messages over the non-3GPP connection. Therefore, the User Equipment 500 can selectively transmit non-initial uplink NAS messages over either 3GPP or non-3GPP connections, depending on whether access over the 3GPP connection is blocked. Figure 6 is a block diagram of a 600 communication system in several configurations. The 600 communication system includes a core network 605 accessible via a radio access network comprising a 5G-compliant base station 610 and a Wi-Fi-compliant access point 615. Some configurations of the 600 communication system are accessible via other devices operating according to the RATs, either in place of the base station 610 and access point 615 or in combination with them. The 600 communication system includes a 620 user equipment that is used to implement some modes of the 140 user equipment shown in FIG. 1 and the 500 user equipment shown in FIG. 5. User Equipment 620 includes a transceiver 625 for transmitting and receiving signals via antenna 630. Some versions of transceiver 625 include multiple radios for communicating using different radio access technologies, such as a radio 635 for communication via a 3GPP connection 640 to base station 610 and a radio 645 for communication in unlicensed Wi-Fi frequency bands via a non-3GPP connection 650. User Equipment 620 also includes a processor 655 and memory 660. The processor 655 executes instructions stored in memory 660 and stores information in memory 660, such as the results of executed instructions.Some modes of the 625 transceiver, the 655 processor, and the 660 memory are configured to carry out parts of the 300 message flow shown in FIG. 3 and the 400 message flow shown in FIG. 4. Therefore, the user team 620 can identify and manage the following anomalous case. Anomalous case: Lower layers indicate that the access attempt is blocked. The UE (user equipment) will not initiate the NAS transport procedure initiated by the UE. The UE remains in the current service cell and can apply the normal cell reselection process. If the event that triggered the access attempt was a request from the upper layers to send a mobile-origin SMS via the NAS (for example, the access attempt is classified in access category 6 (which is for mobile-origin SMS) due to a request from the upper layers to send a mobile-origin SMS via NAS) and the UE is registered on the network via 3GPP access and non-3GPP access, the UE can transmit the UL NAS TRANSPORT message via a non-3GPP access, if available. Otherwise, the UE-initiated NAS transport procedure is initiated, if still necessary, when the lower layers indicate that the block has been eased for the access category with which the access attempt was associated. In some embodiments, certain aspects of the techniques described above can be implemented by one or more processors of a processing system running software. The software comprises one or more sets of executable instructions stored or otherwise tangibly embodied in a non-transient, computer-readable storage medium. The software may include instructions and certain data that, when executed by one or more processors, manipulate the processor(s) to perform one or more aspects of the techniques described above. The non-transient, computer-readable storage medium may include, for example, a magnetic or optical disk storage device, solid-state storage devices such as flash memory, a cache, random-access memory (RAM), or other non-volatile memory devices, and the like.Executable instructions stored on non-transient, computer-readable storage medium may be in source code, assembly language code, object code, or other instruction format that can be interpreted or otherwise executed by one or more processors. A computer-readable storage medium can include any storage medium, or a combination of storage media, that can be accessed by a computer system during use to provide instructions and / or data to the computer system. Such storage media may include, but are not limited to, optical media (e.g., compact disc (CD), digital versatile disc (DVD), Blu-ray disc), magnetic media (e.g., floppy disk, magnetic tape, or magnetic hard disk), volatile memory (e.g., random access memory (RAM) or cache), non-volatile memory (e.g., read-only memory (ROM) or flash memory), or storage media based on microelectromechanical systems (MEMS).The computer-readable storage medium can be integrated into the computer system (e.g., system RAM or ROM), permanently connected to the computer system (e.g., a magnetic hard disk), removablely connected to the computer system (e.g., an optical disk or USB-based flash memory), or connected to the computer system via a wired or wireless network (e.g., network-accessible storage (NAS)). Note that not all activities or elements described above in the general description are required, that part of a specific activity or device may not be necessary, and that one or more additional activities or elements may be performed in addition to those described. Furthermore, the order in which the activities are listed is not necessarily the order in which they are performed. Additionally, the concepts have been described with reference to specific modalities. However, a person skilled in the art will understand that various modifications and changes can be made without departing from the scope of this description, as set forth in the claims below. Accordingly, the description and figures should be considered illustrative rather than restrictive, and it is intended that all such modifications fall within the scope of this description.Benefits, other advantages, and solutions to problems have been described above with respect to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature or features that may generate or make any benefit, advantage, or solution more pronounced should not be construed as a fundamental, required, or essential feature of any or all of the claims. Furthermore, the particular embodiments described above are merely illustrative, as the subject matter may be modified and implemented in different, though equivalent, ways, which will be evident to those skilled in the art who have the benefit of the indications herein. The details of construction and design shown herein are not intended to be limited beyond what is described in the following claims.Therefore, it is evident that the specific modalities described above may be altered or modified, and that such variations are considered to fall within the scope of the subject matter described. Consequently, the protection sought herein is that set forth in the claims below.

Claims

1. A method comprising: generating, in a first layer of a user equipment operating in a connected mode, a request to send a non-initial no-access stratum (NAS) message through a first connection operating in accordance with a first radio access technology (RAT); determining, in a second layer of the user equipment, whether access to the first connection is blocked for the non-initial NAS message; and selecting, from the first layer of the user equipment, between the first connection and a second connection operating in accordance with a second RAT to deliver the non-initial NAS message in response to the blocking of access to the first connection.

2. The method of claim 1, wherein selecting the connection to deliver the non-initial NAS message comprises ceasing the request in response to blocking access to the first connection.

3. The method of claim 2, wherein the user equipment remains in a current cell and applies a cell reselection process in response to the blocking of access to the first connection.

4. The method of claim 2, wherein selecting the connection to deliver the non-initial NAS message comprises requesting to send the non-initial NAS message to the second layer after ceasing the request in response to the blocking being relieved.

5. The method of claim 4, wherein requesting to send the non-initial ÑAS message to the second layer after ceasing the request comprises requesting to send the non-initial ÑAS message to the second layer after ceasing the request in response to the relief of the lock for an access category associated with the non-initial ÑAS message.

6. The method of claim 2, wherein selecting the connection to deliver the non-initial NAS message comprises requesting to send the non-initial NAS message to a third layer of the user equipment associated with the second connection in response to the blocking of access to the first connection.

7. The method of claim 6, further comprising: transmitting, from the third layer, the non-initial NAS message through the second connection in response to the request to send the non-initial NAS message.

8. The method of claim 1, wherein the non-initial ÑAS message is an uplink ÑAS transport message to carry a mobile source Short Message Service (SMS) message, an uplink ÑAS transport message to establish a Packet Data Unit (PDU) session, or an uplink ÑAS transport message to modify the PDU session.

9. The method of claim 8, wherein the first layer is a NAS layer and wherein the second layer is a radio resource control layer.

10. A user equipment comprising: a processor configured to implement a first layer and a second layer, wherein the first layer is configured to generate a request to send a non-initial no-access stratum (NAS) message through a first connection operating in accordance with a first radio access technology (RAT) while the user equipment is operating in a connected mode, and wherein the second layer is configured to determine whether access to the first connection is blocked for the non-initial NAS message; and a transmitter operating in accordance with the first RAT and a second RAT, wherein the first layer is configured to select between the first connection and a second connection operating in accordance with the second RAT to deliver the non-initial NAS message in response to the blocking of access to the first connection.

11. The user equipment of claim 10, wherein the first layer is configured to cease requesting in response to blocking access to the first connection.

12. The user equipment of claim 11, wherein the user equipment remains in a current cell and applies a cell reselection process in response to the blocking of access to the first connection.

13. The user equipment of claim 11, wherein the first layer is configured to request sending the non-initial NAS message to the second layer after ceasing the request in response to the lock being relieved.

14. The user equipment of claim 13, wherein the first layer is configured to request to send the non-initial ÑAS message to the second layer after ceasing the request in response to the relief of the lock for an access category associated with the non-initial ÑAS message.

15. The user equipment of claim 11, wherein the first layer is configured to request sending the non-initial NAS message to a third layer of the user equipment associated with the second connection in response to the blocking of access to the first connection.

16. The user equipment of claim 15, wherein the third layer is configured to transmit the non-initial NAS message through the second connection in response to the request to send the non-initial NAS message.

17. The user equipment of claim 10, wherein the non-initial NAS message is at least one of an uplink NAS transport message to carry a mobile source Short Message Service (SMS) message, an uplink NAS transport message to establish a Packet Data Unit (PDU) session, or an uplink NAS transport message to modify the PDU session.

18. The user equipment of claim 17, wherein the first layer is a NAS layer and wherein the second layer is a radio resource control layer.

19. An apparatus comprising at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least: generate, in a first layer of the apparatus operating in a connected mode, a request to send a non-initial no-access stratum (NAS) message through a first connection operating in accordance with a first radio access technology (RAT); determine, in a second layer of the apparatus, whether access to the first connection is blocked for the non-initial NAS message; and select, from the first layer of the apparatus, between the first connection and a second connection operating in accordance with a second RAT to deliver the non-initial NAS message in response to the blocking of access to the first connection.

20. The apparatus of claim 19, wherein the non-initial NAS message is at least one of an uplink NAS transport message for transmitting a mobile-source Short Message Service (SMS) message, an uplink NAS transport message for establishing a Packet Data Unit (PDU) session, or an uplink NAS transport message for modifying the PDU session, and wherein the first layer is a NAS layer and the second layer is a radio resource control layer.

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