Method and apparatus for enhancing user equipment (UE) processing in a restricted service state on non-3GPP access

Abstract

A method for enhancing user equipment (UE) processing in a restricted service state on a non-3rd Generation Partnership Project (non‑3GPP) access is provided. The UE sends a registration request message or a service request message to a public land mobile network (PLMN) via a non-3GPP access. The UE receives a registration reject message or a service reject message from the PLMN via the non-3GPP access. In particular, the registration reject message or the service reject message indicates that the serving network is not authorized. In response to receiving the registration reject message or the service reject message indicating that the serving network is not authorized, the UE enters a restricted service state and performs non-3GPP access network selection.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 63 / 187,444, filed on May 12, 2021, entitled “LIMITED-SERVICE state and network selection for non-3GPP access,” the subject matter of which is incorporated herein by reference. Technical Field

[0003] The present application relates generally to mobile communications, and more particularly to enhancements to User Equipment (UE) handling in a restricted service state on non-Third Generation Partnership Project (non-3GPP) accesses. Background Art

[0004] In a typical mobile communication environment, a UE (also called a mobile station (MS)), such as a mobile phone (also called a cellular or cell phone) or a tablet personal computer (PC), has wireless communication capabilities and can communicate voice and / or data signals with one or more service networks. Wireless communication between the UE and the service network can be performed using various radio access technologies (RATs), including RATs specified by the Third Generation Partnership Project (3GPP) (referred to herein as 3GPP RATs) and RATs not specified by 3GPP (referred to herein as non-3GPP RATs).

[0005] For example, non-3GPP RAT may include Wireless-Fidelity (Wi-Fi) technology, Bluetooth (BT) technology, Zigbee technology, wired technology, etc. 3GPP RAT may include Global System for Mobile communications (GSM) technology, General Packet Radio Service (GPRS) technology, Enhanced Data rates for Global Evolution (EDGE) technology, Wideband Code Division Multiple Access (WCDMA) technology, Code Division Multiple Access 2000 (CDMA-2000) technology, Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) technology, Long Term Evolution (LTE) technology, TD-LTE technology, Advanced LTE (LTE-Advanced, LTE-A) technology, New Radio (NR) technology, etc. In particular, GSM / GPRS / EDGE technology is also called 2G technology; WCDMA / CDMA-2000 / TD-SCDMA technology is also called 3G technology; LTE / LTE-A / TD-LTE technology is also called 4G technology; and NR technology is also called 5G technology.

[0006] To an increasing extent, most UEs can support multiple RATs to always provide users with more flexible mobile communications. For example, a UE can support one or more 3GPP RATs and non-3GPP RATs, where the non-3GPP RATs can provide better service quality than the 3GPP RATs in indoor environments, and the 3GPP RATs can provide better service quality than the non-3GPP RATs in outdoor environments.

[0007] According to the 3GPP specifications and / or requirements in accordance with 5G NR technology, a UE registered / registered to a roaming public land mobile network (PLMN) through non-3GPP access shall enter the PLMN search (PLMN-SEARCH) substate and perform the 3GPP access PLMN selection process when the non-3GPP access cannot obtain normal services from the PLMN. However, the PLMN-SEARCH substate is not applicable to non-3GPP access scenarios, and the 3GPP access PLMN selection process is not applicable to non-3GPP access scenarios. Therefore, in the case where the UE cannot obtain normal services from the PLMN through non-3GPP access, incorrect UE behavior may occur. Summary of the invention

[0008] In one aspect of the present application, a method performed by a UE is provided. The method includes the following steps: sending a registration request message or a service request message to a PLMN through a non-3GPP access; receiving a registration rejection message or a service rejection message from the PLMN through the non-3GPP access, wherein the registration rejection message or the service rejection message indicates that the service network is not authorized; in response to receiving a registration rejection (REGISTRATION REJECT) message or a service rejection (SERVICE REJECT) message indicating that the service network is not authorized, entering a restricted service state and performing non-3GPP access network selection.

[0009] In another aspect of the present application, a UE including a wireless transceiver and a controller is provided. The wireless transceiver is configured to perform wireless transmission and reception to and from a PLMN via non-3GPP access. The controller is coupled to the wireless transceiver and configured to use the wireless transceiver to perform the following operations: send a registration request message or a service request message to the PLMN via non-3GPP access; receive a registration rejection message or a service rejection message from the PLMN via non-3GPP access, wherein the registration rejection message or the service rejection message indicates that the service network is not authorized; in response to the registration rejection message or the service rejection message indicating that the service network is not authorized, enter a restricted service state and perform non-3GPP access network selection.

[0010] In one example, the registration rejection message or the service rejection message includes a 5G Mobility Management (5GMM) cause value indicating that the serving network is not authorized. The 5GMM cause value may be 73.

[0011] In one example, the limited service state is a 5GMM-DEREGISTERED.LIMITED-SERVICE state in which the UE is able to perform non-3GPP access network selection.

[0012] In one example, the non-3GPP access network selection is a PLMN selection procedure using a trusted non-3GPP access, or a PLMN selection procedure using a wired access, or a non-3GPP access network (Non-3GPP Access Network, N3AN) node selection procedure.

[0013] In one example, the UE further updates the prohibited PLMN list by storing the PLMN identifier of the PLMN in the prohibited PLMN list, where the prohibited PLMN list is a prohibited PLMN list for non-3GPP access to a 5G core network (CN). The updated prohibited PLMN list is then used to perform non-3GPP access network selection.

[0014] In one example, the PLMN is a roaming PLMN.

[0015] In one example, the registration request includes a 5G System (5GS) registration type indicating an initial registration, a mobility registration update, or a periodic registration update.

[0016] According to the method and user equipment for processing user equipment in an enhanced restricted service state on non-3GPP provided in the present application, when the user equipment cannot obtain normal service from the PLMN through non-3GPP access, it can enter the restricted service state and perform non-3GPP access network selection.

[0017] Other aspects and features of the present application will become apparent to those skilled in the art upon reading the following description of specific embodiments of methods and apparatus for enhancing UE processing in a limited service state on non-3GPP access. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present application may be more fully understood by reading the following detailed description and examples with reference to the accompanying drawings, in which:

[0019] Figure 1 is a block diagram of a mobile communication environment according to an embodiment of the present application;

[0020] Figure 2 is a block diagram of a UE according to an embodiment of the present application;

[0021] Figure 3 is an exemplary message sequence chart showing UE processing in a restricted service state on non-3GPP access according to an embodiment of the present application;

[0022] Figure 4 is an exemplary message sequence chart showing UE processing in a restricted service state on non-3GPP access according to another embodiment of the present application;

[0023] Figure 5 is an exemplary message sequence chart showing UE processing in a restricted service state on non-3GPP access according to another embodiment of the present application; and

[0024] Figure 6 It is a flowchart of a method for enhancing UE processing in a restricted service state on non-3GPP access according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] The following description is made to illustrate the general principles of the present application and should not be construed as limiting. It should be understood that the embodiments may be implemented by software, hardware, firmware, or any combination thereof. The terms "comprise," "comprsing," "include," and / or "including," when used in the present invention, specify the presence of the features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0026] Figure 1 It is a block diagram of a mobile communication environment according to an embodiment of the present application.

[0027] The mobile communication environment 100 includes a UE 110 , a 3GPP access 120 , a non-3GPP access 130 , and a 3GPP core network, such as a 5G Core Network (5GCN) 140 .

[0028] UE 110 may be a feature phone, a smartphone, a tablet personal computer (PC), a laptop, a machine type communication (MTC) device, or any mobile communication device that supports the RAT used by 3GPP access 120, non-3GPP access 130, and 5GCN 140.

[0029] UE 110 may be wirelessly connected to 5GCN 140 via 3GPP access 120 and / or non-3GPP access 130. For example, UE 110 may communicate with 5GCN 140 via 3GPP access 120 and / or via non-3GPP access 130 to obtain mobile services (e.g., voice and / or data services).

[0030] 3GPP access 120 may refer to an access network that uses one of the RATs specified by 3GPP. For example, 3GPP access 120 may include GSM EDGE Radio Access Network (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved UTRAN (E-UTRAN), or Next Generation Radio Access Network (NG-RAN).

[0031] In one embodiment, if the RAT used is GSM / EDGE / GPRS technology, the 3GPP access 120 may include GERAN, and the GERAN may include at least a Base Transceiver Station (BTS) and a Base Station Controller (BSC).

[0032] In one embodiment, if the used RAT is WCDMA technology, the 3GPP access 120 may include UTRAN, and the UTRAN may include at least one NodeB (NB).

[0033] In one embodiment, if the RAT used is LTE / LTE-A / TD-LTE technology, the 3GPP access 120 may include E-UTRAN, and the E-UTRAN may include at least one evolved NodeB (eNB) (e.g., macro eNB, femto eNB, or pico eNB).

[0034] In one embodiment, if the RAT used is 5G NR technology, the 3GPP access 120 may include NG-RAN, and the NG-RAN may include one or more gNBs. Each gNB may also include one or more transmission reception points (TRPs), and each gNB or TRP may be referred to as a 5G cell site. Some gNB functions may be distributed across different TRPs, while others may be centralized, allowing flexibility and scope for specific deployments to meet the requirements of specific situations.

[0035] Non-3GPP access 130 may refer to an access network using a RAT not specified by 3GPP. For example, non-3GPP access 130 may include a Wi-Fi network, a WiMAX network, a CDMA network, or a fixed network (eg, a Digital Subscriber Line (DSL) network).

[0036] Each of the 3GPP access 120 and the non-3GPP access 130 can provide functions for processing radio signals, terminating radio protocols, and connecting the UE 110 with the 5GCN 140, while the 5GCN 140 is responsible for performing mobility management, network-side authentication, and interfaces with public / external data networks (e.g., the Internet). In one example, the 5GCN 140 may belong to a roaming PLMN.

[0037] 5GCN 140 may also be referred to as Next Generation Core Network (NG-CN) in 5G NR technology, which may support various network functions, including Access and Mobility Management Function (AMF), Session Management Function (SMF), User Plane Function (UPF), Policy Control Function (PCF), Application Function (AF), Authentication Server Function (AUSF), and Non-3GPP Inter-Working Function (N3IWF), where each network function may be implemented as a network unit on dedicated hardware, or as a software instance running on dedicated hardware, or as a virtualized function instantiated on an appropriate platform (e.g., cloud infrastructure).

[0038] AMF provides UE-based authentication, authorization, mobility management, etc. SMF is responsible for session management and assigns Internet Protocol (IP) addresses to UEs. It also selects and controls UPF for data transmission. If a UE has multiple sessions, different SMFs can be assigned to each session to manage them individually and possibly provide different functions for each session. AF provides information about packet flows to the PCF responsible for policy control to support Quality of Service (QoS). Based on this information, the PCF determines policies on mobility and session management to enable the normal operation of the AMF and SMF. AUSF stores the UE's authentication data, while UDM stores the UE's subscription data. N3IWF enables the UE 110 to attach to the 5GCN 140 via a trusted non-3GPP access or via an untrusted non-3GPP access.

[0039] According to one novel aspect, the UE 110 is allowed to enter a restricted service state (e.g., 5GMM-DEREGISTERED.LIMITED-SERVICE state) and perform non-3GPP access network selection as defined in 3GPP TS 24.502 when it is unable to obtain normal service from the 5GCN 140 via the non-3GPP access 130 due to receiving a 5GMM cause value indicating that the UE subscription in use is not allowed to operate in the PLMN, or the UE subscription includes roaming service but the UE is not in the appropriate tracking area, or the serving network fails to obtain authorization for the UE's home network. Advantageously, the UE 110 is able to enter the correct state that allows the non-3GPP access network selection to be performed to obtain normal service from the PLMN via the non-3GPP access.

[0040] It should be understood that Figure 1 The 5GCN 140 depicted in the figure is for illustration purposes only and is not intended to limit the scope of the present application. For example, the UE 110 can be wirelessly connected to other 3GPP core networks (e.g., future evolutions of 5GCN, such as 6GCN and 7GCN, etc.) via non-3GPP access 130 and apply the method of the present application.

[0041] Figure 2 It is a block diagram of a UE according to an embodiment of the present application.

[0042] like Figure 2 As shown, the UE may include two wireless transceivers 10 and 20 , a controller 30 , a storage device 40 , a display device 50 , and an input / output (I / O) device 60 .

[0043] The wireless transceiver 10 is configured to perform wireless transmission and reception with the 3GPP access 120 .

[0044] Specifically, the wireless transceiver 10 may include a baseband processing device 11, a radio frequency (RF) device 12, and an antenna 13, wherein the antenna 13 may include an antenna array for beamforming.

[0045] The baseband processing device 11 is configured to perform baseband signal processing and control communication between a universal integrated circuit card (UICC) (not shown) and the RF device 12. In one embodiment, the UICC may be a subscriber identity module (SIM) card or a universal SIM (USIM) card and may be inserted into a slot of the UE. In another embodiment, the UICC may be a virtual SIM / USIM or a soft SIM / USIM and may be embedded inside the UE (e.g., may be written into the storage device 40). The baseband processing device 11 may include a plurality of hardware components, such as a baseband processor, to perform baseband signal processing, such as analog-to-digital conversion (ADC) / digital-to-analog conversion (DAC), gain adjustment, modulation / demodulation, encoding / decoding, etc.

[0046] The RF device 12 can receive an RF wireless signal through an antenna 13, convert the received RF wireless signal into a baseband signal, and process it by the baseband processing device 11, or receive a baseband signal from the baseband processing device 11 and convert the received RF wireless signal into a baseband signal. The RF device 12 may also include multiple hardware devices to perform radio frequency conversion. For example, the RF device 12 may include a mixer to multiply the baseband signal with a carrier oscillating in the radio frequency of the supported RAT, where the radio frequency may be 900 MHz, 1800 MHz, or 1900 MHz used in a GSM / EDGE / GPRS system, or may be 900 MHz, 1900 MHz, or 2100 MHz used in a WCDMA system, or may be 900 MHz, 2100 MHz, or 2.6 GHz used in an LTE / LTE-A / TD-LTE system, or any radio frequency used in a 5G (e.g., NR) system (e.g., below 6 GHz, 24.25 GHz to 52.6 GHz for millimeter waves), or other radio frequencies, depending on the RAT used.

[0047] The wireless transceiver 20 is configured to perform wireless transmission and reception with the non-3GPP access 130. In one embodiment, if the RAT used by the non-3GPP access 130 is Wi-Fi technology, the wireless transceiver 20 may be implemented as a Wi-Fi chip.

[0048] Specifically, the wireless transceiver 20 may include a baseband processing device 21, an RF device 22, and an antenna 23. In one example, if the supported Wi-Fi version is 802.11ac or any advanced version supporting beamforming technology, the antenna 23 may also include an antenna array for beamforming.

[0049] The baseband processing device 21 is configured to perform baseband signal processing. The baseband processing device 21 may include multiple hardware components, such as a baseband processor, to perform baseband signal processing, such as ADC / DAC, gain adjustment, modulation / demodulation, encoding / decoding, etc.

[0050] The RF device 22 may receive an RF wireless signal through an antenna 23, convert the received RF wireless signal into a baseband signal, which is processed by the baseband processing device 21, or receive a baseband signal from the baseband processing device 21, and convert the received baseband signal into an RF wireless signal, which is then transmitted via the antenna 23. The RF device 22 may also include a plurality of hardware devices to perform radio frequency conversion. For example, the RF device 22 may include a mixer to multiply a baseband signal with a carrier oscillating in a radio frequency of a supported RAT, where the radio frequency may be 2.4 GHz or 5 GHz used in a Wi-Fi system, or may be 2.402 to 2.480 GHz used in a BT system, or other radio frequencies, depending on the RAT used.

[0051] In another embodiment, the wireless transceivers 10 and 20 may be combined into a single wireless transceiver. That is, the single wireless transceiver may include a combined RF device to support wireless transceivers with the 3GPP access 120 and the non-3GPP access 130, and a combined baseband processor (also referred to as a baseband modem) to handle signaling tasks in accordance with the RAT standards used by the 3GPP access 120 and the non-3GPP access 130.

[0052] The controller 30 can be a general-purpose processor, a micro control unit (MCU), an application processor, a digital signal processor (DSP), a graphics processing unit (GPU), a holographic processing unit (HPU), a neural processing unit (NPU), etc. It includes various circuits for providing data processing and computing functions, controlling the wireless transceiver 10 to wirelessly communicate with the 3GPP access 120, controlling the wireless transceiver 20 to wirelessly communicate with the non-3GPP access 130, storing and retrieving data (for example, program code and / or a prohibited PLMN list (for non-3GPP access 5GCN)) to the storage device 40, sending a series of frame data (for example, representing text messages, graphics, images, etc.) to the display device 50, and receiving user input or output signals through the I / O device 60.

[0053] In particular, the controller 30 coordinates the above operations of the wireless transceivers 10 and 20 , the storage device 40 , the display device 50 , and the I / O device 60 to perform the method of the present application.

[0054] In another embodiment, the controller 30 may be incorporated into the baseband processing device 11 or the baseband processing device 21 to function as a baseband processor.

[0055] As will be appreciated by those skilled in the art, the circuitry of the controller 30 may include transistors configured to control the operation of the circuitry in accordance with the functions and operations described herein. As will be further appreciated, the specific structure or interconnection of the transistors may be determined by a compiler, such as a Register Transfer Language (RTL) compiler. The RTL compiler may be operated by a processor based on a script that is very similar to assembly language code to compile the script into a form for layout or manufacture of the final circuit. In fact, RTL is well known for its role and use in facilitating the design of electronic and digital systems.

[0056] The storage device 40 may be a non-temporary machine-readable storage medium, including a memory, such as a flash memory or a non-volatile random access memory (NVRAM), or a magnetic storage device, such as a hard disk or a tape, or an optical disk, or any combination thereof, for storing applications, communication protocols (e.g., Wi-Fi protocols, and / or 5G protocols, etc.), and / or data of the method of the present application (e.g., a prohibited PLMN list (for non-3GPP access to 5GCN)), instructions and / or program codes. In one example, the method of the present application may be implemented as part of a 5G protocol. The 5G protocol stack generally includes a non-access stratum (NAS) layer that communicates with the AMF / SMF / MME entities in the 3GPP core network, and an access stratum (AS) layer composed of multiple sublayers, such as the control (RRC) sublayer for high-level configuration and control, the packet data convergence protocol / radio link control (PDCP / RLC) sublayer, the media access control (MAC) sublayer and the physical (PHY) sublayer.

[0057] The display device 50 may be a liquid crystal display (LCD), a light-emitting diode (LED) display, an organic LED (OLED) display, or an electronic paper display (EPD), etc., for providing a display function. Alternatively, the display device 50 may further include one or more touch sensors for sensing the touch, contact, or proximity of an object such as a finger or a stylus.

[0058] The I / O device 60 may include one or more buttons, keyboards, mice, touch pads, cameras, microphones and / or speakers, etc., to serve as a man-machine interface (MMI) for interacting with a user.

[0059] It should be understood that Figure 2The components described in the embodiments are for illustrative purposes only and are not intended to limit the scope of the present application. For example, the UE may include more components, such as a power supply (e.g., a removable / replaceable battery) for powering other components of the UE, and / or a global positioning system (GPS) device for use with some location-based services or applications. Optionally, the UE may include fewer components. For example, the UE may not include a display device 50 and / or an I / O device 60.

[0060] Figure 3 It is an exemplary message sequence chart showing UE processing in a restricted service state on non-3GPP access according to an embodiment of the present application.

[0061] In this embodiment, the UE processes related initial registration which is not accepted by the network.

[0062] In step S310, the UE sends a registration request (REGISTRATION REQUEST) message to the PLMN via non-3GPP access. The registration request may include a 5GS registration type indicating an initial registration. In one example, the PLMN is a roaming PLMN.

[0063] In step S320, the UE receives a REGISTRATION REJECT message from the PLMN via non-3GPP access. Specifically, the REGISTRATION REJECT message may include a 5GMM cause value #73 "Serving network not authorized".

[0064] If the UE initiates registration with the serving network and the serving network fails to be authorized by the UE's home network, a 5GMM cause value #73 is sent to the UE.

[0065] In step S330, the UE stores the PLMN identifier of the PLMN in a prohibited PLMN list for non-3GPP access to 5GCN (i.e., a prohibited PLMN list for non-3GPP access to 5GCN).

[0066] In step S340, the UE enters the limited service state and performs the network selection defined in 3GPP TS 24.502 (i.e., non-3GPP access network selection). Specifically, the limited service state is a state in which the UE can perform non-3GPP access network selection (e.g., 5GMM-DEREGISTERED.LIMITED-SERVICE), and performs non-3GPP access network selection using the updated forbidden PLMN list.

[0067] The non-3GPP access network selection may be a PLMN selection process using a trusted non-3GPP access, or a PLMN selection process using a wired access, or a non-3GPP access network (Non-3GPP Access Network, N3AN) node selection process.

[0068] Figure 4 is an exemplary message sequence chart showing UE processing in a restricted service state on non-3GPP access according to another embodiment of the present application.

[0069] In this embodiment, the UE processes a mobility registration update or a periodic registration update which is not accepted by the network.

[0070] In step S410, the UE sends a registration request message to the PLMN via non-3GPP access. The registration request may include a 5GS registration type indicating a mobility registration update or a periodic registration update. In one example, the PLMN is a roaming PLMN.

[0071] In step S420, the UE receives a registration rejection message from the PLMN via non-3GPP access. Specifically, the registration rejection message may include a 5GMM cause value #73 "Service network not authorized".

[0072] If the UE initiates registration with the serving network and the serving network fails to be authorized by the UE's home network, a 5GMM cause value #73 is sent to the UE.

[0073] In step S430, the UE stores the PLMN identifier of the PLMN in the prohibited PLMN list for non-3GPP access to 5GCN (i.e., the PLMN prohibited list for non-3GPP access to 5GCN).

[0074] In step S440, the UE enters the limited service state and performs network selection defined in 3GPP TS 24.502 (i.e., non-3GPP access network selection). Specifically, the limited service state is a state in which the UE can perform non-3GPP access network selection (e.g., 5GMM-DEREGISTERED.LIMITED-SERVICE), and performs non-3GPP access network selection using the updated forbidden PLMN list.

[0075] The non-3GPP access network selection may be a PLMN selection procedure using a trusted non-3GPP access, or a PLMN selection procedure using a wired access, or a N3AN node selection procedure.

[0076] Figure 5 is an exemplary message sequence chart showing UE processing in a restricted service state on non-3GPP access according to another embodiment of the present application.

[0077] In this embodiment, the UE processes a service request procedure that is not accepted by the network.

[0078] In step S510, the UE sends a service request message to the PLMN through non-3GPP access. The registration request may include a service type for specifying the purpose of the service request process. For example, the service type may indicate "signaling", "data", "mobile terminated service", "emergency service", "emergency service fallback", "high priority access" or "promoted signaling". In one example, the PLMN is a roaming PLMN.

[0079] In step S520, the UE receives a service rejection message from the PLMN via non-3GPP access. Specifically, the service rejection message may include a 5GMM cause value #73 "Service network not authorized".

[0080] If the UE initiates registration with the serving network and the serving network fails to be authorized by the UE's home network, a 5GMM cause value #73 is sent to the UE.

[0081] In step S530, the UE stores the PLMN identifier of the PLMN in the prohibited PLMN list for non-3GPP access to 5GCN (i.e., the PLMN prohibited list for non-3GPP access to 5GCN).

[0082] In step S540, the UE enters the limited service state and performs network selection defined in 3GPP TS 24.502 (i.e., non-3GPP access network selection). Specifically, the limited service state is a state in which the UE can perform non-3GPP access network selection (e.g., 5GMM-DEREGISTERED.LIMITED-SERVICE), and performs non-3GPP access network selection using the updated forbidden PLMN list.

[0083] The non-3GPP access network selection may be a PLMN selection procedure using a trusted non-3GPP access, or a PLMN selection procedure using a wired access, or a N3AN node selection procedure.

[0084] Figure 6 is a flow chart showing a method for enhancing UE processing in a limited service state on non-3GPP access according to an embodiment of the present application.

[0085] The method for enhancing UE processing in a limited service state on non-3GPP access may be applied to and performed by a UE (eg, UE 110) supporting access to a PLMN through a non-3GPP access.

[0086] In step S610, the UE sends a registration request message or a service request message to the PLMN via non-3GPP access. In one example, the PLMN is a roaming PLMN. In one example, the registration request includes a 5GS registration type indicating an initial registration, a mobility registration update, or a periodic registration update.

[0087] In step S620, the UE receives a registration rejection message or a service rejection message from the PLMN through non-3GPP access, wherein the registration rejection message or the service rejection message indicates that the serving network is not authorized. In one example, the registration rejection message or the service rejection message includes a 5GMM cause value (e.g., 73) indicating that the serving network is not authorized. In another embodiment, the UE may not send a message in step S610 and the UE receives a deregistration request including a 5GMM cause value (e.g., 73) indicating that the serving network is not authorized in step S620.

[0088] In step S630, the UE enters a limited service state and performs non-3GPP access network selection in response to receiving a registration rejection message or a service rejection message indicating that the serving network is not authorized. In one example, the limited service state is a 5GMM-DEREGISTERED.LIMITED-SERVICE state in which the UE is able to perform non-3GPP access network selection. Non-3GPP access network selection is a PLMN selection process using a trusted non-3GPP access, or a PLMN selection process using a wired access, or a N3AN node selection process.

[0089] In another embodiment, in response to receiving a registration rejection message or a service rejection message indicating that the service network is not authorized, the UE can update the prohibited PLMN list by storing the PLMN identifier of the PLMN in a prohibited PLMN list which is a list of prohibited PLMNs for non-3GPP access to 5GCN, and the updated prohibited PLMN list can be used to perform non-3GPP access network selection.

[0090] Although the present application has been described by way of examples and preferred embodiments, it should be understood that the present application is not limited thereto. Without departing from the scope and spirit of the present application, those skilled in the art can still make various changes and modifications. Therefore, the scope of the present application should be defined and protected by the appended claims and their equivalents.

Claims

1. A method for processing a user equipment in a restricted service state on a non-3GPP network, comprising: Sending a registration request message or a service request message to a public land mobile network (PLMN) via a non-3rd Generation Partnership Project (3GPP) access; receiving a registration reject message or a service reject message from the PLMN through non-3GPP access, wherein the registration reject message or the service reject message indicates that the serving network is not authorized, and the registration reject message or the service reject message includes a 5G mobility management cause value indicating that the serving network is not authorized, and the 5G mobility management cause value is 73; as well as In response to receiving the registration rejection message or the service rejection message indicating that the service network is not authorized, entering a limited service state and performing non-3GPP access network selection.

2. The method according to claim 1, characterized in that The restricted service state is a 5G mobility management deregistered restricted service state, wherein the user equipment is capable of performing the non-3GPP access network selection.

3. The method according to claim 1, characterized in that The non-3GPP access network selection is a PLMN selection process using a trusted non-3GPP access, or a PLMN selection process using a wired access, or a non-3GPP access network node selection process.

4. The method according to claim 1, further comprising: The prohibited PLMN list is updated by storing the PLMN identifier of the PLMN in the prohibited PLMN list, wherein the prohibited PLMN list is a prohibited PLMN list for non-3GPP access to the 5G core network.

5. The method according to claim 4, characterized in that The non-3GPP access network selection is performed using the updated forbidden PLMN list.

6. The method according to claim 1, characterized in that The PLMN is a roaming PLMN.

7. The method according to claim 1, characterized in that The registration request includes a 5G system registration type indicating an initial registration, a mobility registration update, or a periodic registration update.

8. A user equipment for user equipment processing in a restricted service state on a non-3GPP network, comprising: a wireless transceiver configured to perform wireless transmission and reception with a public land mobile network (PLMN) via a non-3rd Generation Partnership Project (3GPP) access; as well as A controller is coupled to the wireless transceiver and configured to use the wireless transceiver to perform the following operations: Sending a registration request message or a service request message to the PLMN via non-3GPP access; receiving a registration reject message or a service reject message from the PLMN through non-3GPP access, wherein the registration reject message or the service reject message indicates that the serving network is not authorized, and the registration reject message or the service reject message includes a 5G mobility management cause value indicating that the serving network is not authorized, and the 5G mobility management cause value is 73; as well as In response to receiving the registration rejection message or the service rejection message indicating that the service network is not authorized, entering a limited service state and performing non-3GPP access network selection.

9. The user equipment according to claim 8, characterized in that The restricted service state is a 5G mobility management deregistered restricted service state, wherein the user equipment is capable of performing the non-3GPP access network selection.

10. The user equipment according to claim 8, characterized in that The non-3GPP access network selection is a PLMN selection process using a trusted non-3GPP access, or a PLMN selection process using a wired access, or a non-3GPP access network node selection process.

11. The user equipment according to claim 8, characterized in that The controller is also configured to update a forbidden PLMN list by storing a PLMN identifier of the PLMN in a forbidden PLMN list, wherein the forbidden PLMN list is a forbidden PLMN list for non-3GPP access to a 5G core network.

12. The user equipment according to claim 11, characterized in that The non-3GPP access network selection is performed using the updated forbidden PLMN list.

13. The user equipment according to claim 8, characterized in that The PLMN is a roaming PLMN.

14. The user equipment according to claim 8, characterized in that The registration request includes a 5G system registration type indicating an initial registration, a mobility registration update, or a periodic registration update.

15. A non-transitory machine-readable storage medium storing program codes and instructions, which, when used for execution by a processor of a user equipment for enhancing user equipment processing in a restricted service state on a non-3GPP network, enable the user equipment to execute the method as described in any one of claims 1 to 7 above.

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