EP4732631A1

EP4732631A1 - Methods for switching an application access directly between epdg and n3iwf n0n-3gpp access functions

Info

Publication number: EP4732631A1
Application number: EP24758604.3A
Authority: EP
Inventors: Po-Chun Lee; Chien-Chun Huang-Fu; Ai-Chieh LIN
Original assignee: Google LLC
Current assignee: Google LLC
Priority date: 2023-07-28
Filing date: 2024-07-26
Publication date: 2026-04-29
Also published as: KR20260042231A; CN121753472A; WO2025029639A1

Abstract

Methods (600) and a wireless communication devices enable direct switching of an application running on a non-3GPP network between non-3GPP gateways to different 3GPP networks. The direct switching is performed when monitoring (610) the application identifies (620) a low-activity state. The direct switching includes releasing (630) a first connection to a first 3GPP network via a first non-3GPP gateway and establishing (640) a second connection of the application to a second 3GPP network via a second non-3GPP gateway.

Description

METHODS FOR SWITCHING AN APPLICATION ACCESS DIRECTLY BETWEEN EPDG AND N3IWF NON-3GPP ACCESS FUNCTIONS

FIELD OF THE DISCLOSURE

[0001] This document generally describes methods and devices operating in wireless communication systems such as (but not limited to) the ones described in standard documents, known as 3GPP systems.

BACKGROUND

[0002] Mobile networks are increasingly complex and diverse, with the integration of various 3GPP and non-3GPP technologies, such as 5G and wireless local-area networks such as Wi-Fi. Network operators have developed various gateways such as the Evolved Packet Data Gateway (ePDG) and the Non-3GPP Interworking Function (N3IWF) to provide untrusted non-3GPP access to the 3GPP core network. ePDG acts as a termination node of Internet Protocol Security (IPSec) tunnels to enable secure data exchange between a UE running an application connected through an untrusted non-3GPP access network (e.g., Wi-Fi) and a Long Term Evolution (LTE) network system (known as Evolved Packet System, EPS). Similarly, N3IWF, which also supports IPSec connectivity towards the UEs, is responsible for interworking between a UE running an application connected through an untrusted non-3GPP network and the 5G system (5GS). Conventionally, after an application running on a non-3GPP network connects to a 3GPP network via a non-3GPP access, it does not contemplate switching to another 3GPP system when such an alternative system becomes available, and even though switching 3GPP system would be advantageous for the user’s experience.

[0003] Currently, 3GPP documents do not provide techniques usable for switching directly (i.e., without intra-3GPP and inter-3GPP handovers) from a first non- 3GPP access (e.g., ePDG) of a first 3GPP system to a second non-3GPP access (e.g., N3IWF) of a second 3GPP system. Figure 1 is a graphic illustration of the abovedescribed current situation. [0004] An intra-3GPP switching between EPS core 110 (known as EPC) and 5GS core 120 (known as 5GC) may employ 101 an N26 interface that provides a seamless session continuity for single registration mode UE (as described, for example, in 3GPP TS 23.502 section 4.11.1 ).

[0005] Alternatively, intra-3GPP switching between EPS core 110 and 5GS core 120 may be a handover 102 without using the N26 interface (as described, for example, in 3GPP TS 23.502 section 4.11 .2).

[0006] Standardized intra-network handover procedures 103 and 104 have been established for handing over a UE from a first non-3GPP network gateway 130 (e.g., a gateway between non-3GPP system and the EPS) to EPC 110 and from a second non- 3GPP network access 140 (i.e., a gateway between non-3GPP system and the 5GS) to 5GC 120. Further, 3GPP TS 23.502 section 4.11 .3 outlines handover procedures between EPS and 5GC-N3IWF, with subsection 4.11.3.1 describing handover procedures 105 and 108 and subsection 4.11.3.2 describing handover procedures 106 and 107. In this document “access,” “access point”, and “gateway” are used referring to untrusted non-3GPP to 3GPP interface functionality, a physical device implementing the functionality, and effect of the functionality as appropriate.

[0007] Switching of a non-3GPP access between different technologies can cause problems for the user devices (such as UE 150 in Figure 1). The UE may be unable to access the second non-3GPP access (e.g., N3IWF) for various reasons. For example, network congestion may prevent a mobile device from connecting to N3IWF when 5G is the preferred network.

SUMMARY

[0008] Methods and network devices enable switching an application directly between different untrusted non-3GPP gateways while the application is in a low-activity state (e.g., application-related traffic via a currently used non-3GPP access is below a predetermined threshold, and, preferably, no critical service related to the application is running). Although these methods are non-seamless and lose an existing context, the switching disruption is minimized so that the user’s application continues with an insignificant and brief degradation of the quality of service. The security context for the application may be re-established after the non-3GPP gateway switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments.

[0010] Figure 1 is a graphical illustration of the currently available techniques for switching between different non-3GPP gateways.

[0011] Figure 2 is a flow diagram illustrating actions performed by a user equipment (UE) for switching an application between non-3GPP access functions to different 3GPP networks, according to an embodiment.

[0012] Figure 3 illustrates a first scenario for switching an application between non- 3GPP access functions to different 3GPP networks, according to an embodiment.

[0013] Figure 4 illustrates a second scenario for switching an application between non-3GPP access functions, according to another embodiment.

[0014] Figure 5 illustrates a third scenario for switching non-3GPP access functions (using an intra-3GPP intermediate handover).

[0015] Figure 6 is a flowchart of a method for switching non-3GPP access in a direct manner, according to an embodiment.

[0016] Figure 7 is a structural representation of a user equipment, UE, and a non- 3GPP access configured to enable switching non-3GPP gateways according to an embodiment.

DETAILED DESCRIPTION

[0017] Methods and devices described in this section embody techniques related to switching directly between different untrusted non-3GPP access gateways (such as 130 and 140) of two different 3GPP networks (e.g., LTE and 5G). These methods and devices also apply to trusted non-3GPP gateways such as Trusted Non- 3GPP Access Point (TNAP) and Trusted WLAN AAA Proxy (TWAP). In order to minimize disruption, the following embodiments detect that an application, which uses a non-3GPP access (such as ePDG or N3IWF) to one 3GPP network (e.g., LTE or 5G), is in a low-activity state and switch the application to another non-3GPP gateway (e.g., N3IWF or ePDG) of another 3GPP network (e.g., 5G or LTE) without interrupting the ongoing application. The switching is not performed in a seamless manner; that is, a brief data flow interruption may occur. Direct switching of the non-3GPP access does not employ intra-3GPP handover (such as 102 and 103 in Figure 1 ) inter-core 3GPP switching (such as 101) or inter-core-to-gateway handovers (such as 104 to 107). Direct switching includes releasing the application’s existing connection to a 3GPP network and establishing a new connection to another 3GPP network. Note that indirect switching using the intra-3GPP handover and inter-3GPP handover may be seamless (i.e. , without interrupting the data flow).

[0018] Figure 2 is a flow diagram illustrating actions performed by a UE for direct switching of its application running on a non-3GPP radio access network between 3GPP networks according to an embodiment. Initially, the UE connects 201 the application exchanging data using the first non-3GPP gateway to a first 3GPP network (e.g., an LTE network or a 5G network). In other words, the application runs on the UE, which routes application-related data traffic via a non-3GPP gateway (ePDG, N3IWF, TNAP, or TWAP) to a 3GPP core network (EPC or 5GC).

[0019] The UE then evaluates 202 whether to switch to a second 3GPP network via a second non-3GPP access. For example, switching from ePDG 130 to N3IWF 140 allows UE 150 to take advantage of 5GS features (such as access traffic steering, switching and splitting, ATSSS, network slicing, or reflective quality of service, QoS) having a positive impact on the software application. How advantageous it is for the application to use a certain 3GPP network may be quantified as a priority value. For some applications, a 5G network may have a higher priority (e.g., due to the additional features mentioned above) than an LTE network. However, an LTE network with lower traffic may be more advantageous (and therefore have a higher associated priority) than a 5G network when the application requires a more reliable but lower volume data flow at a high mobility. If the application has priority values associated with types of 3GPP networks, the UE’s 202 decision is based on a comparison of the priority values corresponding to the available 3GPP network. In some examples, the UE selects to pursue connection with the 3GPP network associated with the highest priority value among the available 3GPP networks, if that highest priority is higher than the priority value of the serving 3GPP network.

[0020] Further (the YES branch of 202), the UE detects 203 whether the application is in a low-activity state by monitoring or examining various application-related aspects such as access stratum (AS) connection state, user plane state, the most recent packet transmission across the non-3GPP gateway and service state. Application’s low-activity state may be based on low application-related traffic volume (e.g., traffic below a predetermined threshold during the most recent 3 seconds) and/or absence of application- related active critical services (e.g., services that cannot be interrupted).

[0021] Monitoring the application, which is connected to a first 3GPP core network via a first non-3GPP access, enables identifying when the application is in a low-activity state. For example, monitoring the application-related network traffic and usage patterns enables detecting or predicting when no data flow is present or expected for an upcoming time interval (e.g., transmitted over an IPSec tunnel). In another example, monitoring the application enables detecting when application-related user plane resources are released or when an AS connection state is an idle state. In yet another example, monitoring the application enables detecting when there is no active application-related user-awareness session (e.g., no active voice call over IP Multimedia Subsystem, IMS, data connection). [0022] Upon detecting that the application is in a low-activity state (the YES branch of block 203), the UE switches 204 the application to the second non-3GPP gateway as further discussed below. When UE determines not to switc (the NO branch of 202) or that the application is not in a low-activity state (the NO branch of 203), the UE maintains the application connected to the first 3GPP core network via the first non-3GPP access (skipping 204). The UE may repeat performing steps 202 and potentially also 203 periodically or when a predetermined event (such as a different second 3GPP network becoming available) occurs.

[0023] Switching the application, while in a low-activity state, from connecting to a first 3GPP core network via a first non-3GPP access to connecting to a second 3GPP core network via a second non-3GPP gateway (i.e., step 204) may be implemented according to at least the three scenarios: (1) a “break-before-make” scenario, (2) a “make-and- release” scenario and (3) an intra-3GPP intermediate handover scenario. The former two scenarios are non-seamless and use direct non-3GPP gateway type switching, while the latter is seamless and uses indirect non-3GPP gateway type switching.

[0024] Figures 3, 4, and 5 illustrate scenarios for switching an application between non-3GPP IP gateways to different 3GPP networks. In these figures, time flows from the top of the page to bottom, that is, a first action (such as a signal transmission) occurs before a second action represented underneath the first action. These scenarios illustrate various embodiments of step 204, when the UEs, which run an application employing a non-3GPP network such as a Wi-Fi network (trusted or untrusted), have already determined to switch non-3GPP access gateways (the YES branch of step 202), and that the application is in a low-activity state (the YES branch of step 203).

[0025] Figure 3 illustrates the first scenario for switching non-3GPP IP gateways to different core networks (“break-before-make”) according to an embodiment. UE 310 sends 312 a data network release request to first non-3GPP access 320 currently used to connect the application to the first 3GPP core network. First non-3GPP gateway 320 then acknowledges the data network release request by transmitting 314 a data network release response. After performing a local release 315 of communication resources UE used for communicating through first non-3GPP access 320, UE 310 exchanges 316 messages with second non-3GPP access 330 for connecting the application to the second 3GPP core network. UE 310 does not employ 3GPP core networks 340 in this first scenario because the core networks are connected via their respective gateways.

[0026] Figure 4 illustrates a second scenario for switching non-3GPP gateways (“make-and-release”) according to another embodiment. In this scenario, the UE first exchanges messages 416 with second non-3GPP access 430 for connecting the application to the second 3GPP core network. The first non-3GPP gateway 420 then sends 413 a data network release request to the UE. UE 410 acknowledges the data network release request by transmitting 417 a data network release response. Note that in this case the first 3GPP network (not the UE as in the first scenario) initiates releasing the connection with the UE running the application. UE 410 then performs a local release 415 of communication resources that the UE used for communicating with the first non- 3GPP access. UE 410 does not employ 3GPP networks 440 in this second scenario because the core networks are connected via their respective gateways.

[0027] Figure 5 illustrates a third scenario for switching non-3GPP gateways (using an intra-3GPP intermediate handover). Unlike in the above-described first and second scenario, in this third scenario UE 510 employs the 3GPP core networks 540 for non-3GPP access switching. UE 510 initially exchanges 542 messages (e.g., starting with a handover request) with the 3GPP core networks for establishing a connection with a first 3GPP core network via first non-3GPP access 520. Upon determining that using a second 3GPP core network would be advantageous, UE 510 exchanges messages 522 with first non-3GPP access 520 for releasing the first data network connection. Then, UE 520 exchanges messages 532 with second non-3GPP access 530 for establishing the second data network connection. UE 530 also exchanges messages 544 with 3GPP core network 540 for releasing the second data network connection.

[0028] Figure 6 is a flowchart of a method 600 for switching non-3GPP access in a direct manner, according to an embodiment. Method 600 is performed by a wireless communication device (e.g., UE 310 or UE 410) running an application and communicating through a non-3GPP wireless access network (e.g., a trusted or untrusted Wi-Fi network). Method 600 includes monitoring 610 the application, which has a first connection to a first 3GPP core network via a first non-3GPP access (e.g., 320 or 420), to identify a low-activity state of the application. All above-described techniques of identifying the low-activity state may apply individually or in combination.

[0029] Method 600 further includes, upon identifying the low-activity state of the application (i.e., YES branch of 620), releasing 630 the first connection (that is communication resources reserved for communication with the first access), and establishing 640 a second connection of the application to a second 3GPP network via a second non-3GPP access. Establishing the second connection may occur before the releasing of the first connection as shown in FIG. 4 or after as shown in FIG. 3.

[0030] Figure 7 is a structural representation of wireless communication system 700 including a wireless communication device 710 (which may operate as UE 310 or UE 410) and a wireless device 720 hosting a non-3GPP gateway (320, 330, 420, 430) configured to enable direct switching between non-3GPP gateways according to an embodiment.

[0031] Wireless communication device 710 includes antennas connected to a radio frequency (RF) front end 761 , and at least one RF transceiver (such as, an LTE transceiver 762, a 5G NR transceiver 763, or another transceiver 764) for communicating with wireless communication device 720. The antennas and the RF front end 761 can be tuned to one or more frequency bands (e.g., subcarriers), for example, as defined by 3GPP LTE, 5G NR, and 6G communication standards and implemented by respective transceivers. Wireless communication device 710 also includes one or more precoders 765, one or more processor(s) 766, and computer- readable storage media (CRM) 767. Processor(s) 766 may be single or multiple-core processors, and CRM 767 includes any suitable memory/storage other than propagating signals. For example, memory/storage can include random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), and/or flash memory useable to store a direct gateway switching manager 768 and application 769 for implementing various techniques described in this document. CRM 767 stores instructions executable by processor(s) 766 to facilitate user-plane communication, control-plane signaling and user interaction. Direct gateway switching manager 768, which may be implemented not only as software but also as hardware logic and/or circuitry, causes various steps and actions associated with switching application 769, which runs on a non-3GPP network between non-3GPP gateways to different 3GPP networks.

[0032] Wireless device 720 as illustrated in Figure 7 provides functionality of a non-3GPP gateway. Wireless device 720 includes antennas, an RF front end 771 and RF transceiver(s) 772 (there may be more transceivers for different technologies, as illustrated for wireless communication device 710) for communicating with wireless communication device 710 and 3GPP network devices. Wireless device 720’s antennas and RF front end 771 can be tuned to one or more frequency bands (e.g., subcarriers), for example as defined by 3GPP LTE, 5G NR, and 6G communication standards and implemented by RF transceiver(s) 772.

[0033] Wireless device 720 includes processor(s) 773 and computer-readable storage media (CRM) 774. Processor(s) 773 can include single or multiple-core processors, and CRM 774 includes any suitable memory/storage except propagating signals. For example, memory/storage can include random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), and/or flash memory. CRM 774 stores device data 775, which includes network scheduling data, radio resource management data, applications, and/or an operating system, which are executable by processor(s) 773 to enable wireless communication with wireless communication device 710 as well as with 3GPP network devices.

[0034] CRM 774 also stores traffic monitor 776 and switching manager 777, which cause wireless device 720 to perform various steps and actions associated with direct switching of non-3GPP access (such as non-3GPP access 778) of application 769. Wireless device 720 also includes core-network interface 779, which may include a standardized interface, such as an Xn and/or X2 interface, for exchanging userplane and control-plane data within the 3GPP network.

[0035] A wireless system such as the one schematically illustrated in Figure 7 may implement various techniques related to direct non-3GPP gateway switching for an application running on a non-3GPP network.

[0036] The embodiment descriptions in this section refer to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The detailed descriptions do preclude other embodiments within the scope of the appended claims. The embodiments are not limited to the described configurations but may be extended to other arrangements.

[0037] Reference throughout this section to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification are not necessarily all referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0038] Numerical adjectives “first”, “second”, and “third” do not imply any order (are not ordinals) but are markers to distinguish separate instances of similar elements.

References to the singular (e.g., “a” or “an”, “the”) should include the plural unless clearly indicated otherwise.

[0039] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. The methods or flowcharts may be implemented in a computer program, software or firmware tangibly embodied in a computer-readable storage medium for execution by a specifically programmed computer or processor.

Claims

WHAT IS CLAIMED IS:

1 . A method (600) performed by wireless communication device running an application and communication on a non-3GPP radio access network, the method comprising: monitoring (610) the application, which exchanges data using a first connection to a first 3GPP core network via a first non-3GPP gateway, to identify a low-activity state; and upon identifying (620) the low-activity state, releasing (630) the first connection, and establishing (640) a second connection to a second 3GPP core network via a second non-3GPP gateway.

2. The method of claim 1 , wherein one of the first 3GPP core network and the second 3GPP core network is a Long Term Evolution, LTE, core network as defined in 3GPP standard documents and a corresponding one of the first non-3GPP gateway and the second non-3GPP gateway, respectively, is an evolved Packet Data Gateway, ePDG, and another one of the first 3GPP core network and the second 3GPP core network is a 5^th generation, 5G, mobile network as defined in the 3GPP standard documents and another one of the first non-3GPP gateway and the second non-3GPP gateway is a Non-3GPP Interworking Function, N3IWF.

3. The method of claims 1 or 2, wherein the monitoring of the application includes tracking a data traffic related to the application via the first non-3GPP gateway, and the identifying of the low-activity state includes determining that the data traffic is below a predetermined threshold.

4. The method of any of claims 1 to 3, wherein the identifying includes determining that no critical service related to the application is running.

5. The method of any of claims 1 to 4, wherein the second non-3GPP gateway has a higher priority than a priority of the first non-3GPP gateway.

6. The method of any of claims 1 to 5, wherein the releasing of the first connection starts prior to the establishing of the second connection.

7. The method of any of claims 1 to 5, wherein the releasing of the first connection starts after the establishing of the second connection.

8. The method of any of claims 1 to 7, wherein a time interval between the releasing of the first connection and the establishing of the second connection is less than 1 second.

9. The method of any of claims 1 to 8, wherein the releasing of the first connection and the establishing of the second connection do not interrupt the application.

10. The method of any of claims 1 to 9, wherein the identifying of the low- activity state includes detecting a release of user plane resources.

11 . The method of any of claims 1 to 10, wherein the identifying of the low- activity state includes determining an absence of any active user-awareness session related to the application.

12. The method of any of claims 1 to 11 , further comprising: re-establishing a security context for the application after the establishing of the second connection.

13. The method of any of claims 1 to 12, wherein at least one of the first connection and the second connection includes an Internet Protocol security, IPsec, tunnel.

14. The method of any of claims 1 to 12, wherein the non-3GPP radio access network is a wireless local-area network, WLAN, network.

15. The method of any of claims 1 to 1 , wherein the monitoring of the application is triggered by a predetermined event.

16. A wireless communication device (310, 410, 710) comprising a transceiver (762, 763, 764), a processor (766), and computer-readable storage media (767) storing executable instructions (768) for the processor to perform any one of the methods recited in claims 1 -17, using the transceiver.