TWI748461B - Methods for avoiding network fallbacks of a user equipment - Google Patents

Abstract

A method executed by a UE communicatively connected to a first 3rd Generation Partnership Project (3GPP) network utilizing a first Radio Access Technology (RAT) is provided. The methods includes the following steps: receiving a message from the first 3GPP network, which indicates that the first 3GPP network supports IP Multimedia Subsystem (IMS) voice over Packet Switched (PS) sessions; and providing an indication that fallback of the UE to a second 3GPP network utilizing a second RAT is disabled to the first 3GPP network in response to the receiving of the message.

Description

Method for preventing user equipment from executing network fallback

The present application generally relates to wireless communication, and more specifically, relates to a method for preventing a user equipment (User Equipment, UE) from performing a network fallback.

In a typical mobile communication environment, user equipment (UE) (also known as mobile station (Mobile Station, MS)), such as a mobile phone (also known as a cellular phone or cell phone) or a tablet personal computer (PC) with wireless communication capabilities ) Can communicate voice and/or data signals with one or more service networks. The wireless communication between the UE and the service network can be performed using various radio access technologies (Radio Access Technology, RAT), such as Global System for Mobile Communications (GSM) technology, General Packet Radio Service (GPRS) technology, and global data rate enhancement Evolution technology (Enhanced Data rates for Global Evolution, EDGE), 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, microwave Access WiMAX technology, long-term evolution (LTE) technology, advanced LTE (LTE-A) 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.

These RAT technologies have been used in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at municipal, national, regional, and even global levels. An example of an emerging telecommunications standard is 5G New Radio (NR). 5G NR is a set of enhancements to the LTE mobile standard promulgated by the Third Generation Partnership Project (3GPP). It aims to better support mobile broadband Internet access by improving spectrum efficiency, reducing costs and improving services.

According to 3GPP specifications and/or requirements that comply with 5G NR technology, if the 5G network supports IP Multimedia Subsystem (IMS) voice over PS session based on Packet Switched (PS) sessions, but due to For some reasons, the IMS call service cannot be provided natively, and the UE camping on the 5G network can be triggered by the 5G network and fall back to the 4G network to receive the mobile terminal called (Mobile Terminated, MT) voice call. However, in some cases, the UE may be performing a critical operation that requires the UE to maintain a connection with the 5G network during the operation. As a result, the UE falling back to the 4G network may cause disconnection from the 5G network and affect the critical operation.

In order to solve the above problems, this application proposes a specific way to configure the UE and/or the serving network (for example, 5G network) to avoid the UE from performing network fallback (for example, not performing the fallback from the UE to the traditional network (for example 4G)).

In one aspect of the present application, a method performed by a UE communicatively connected to a first third generation partnership project (3GPP) network using a first radio access technology (RAT) is provided. The method includes the following steps: receiving a message from the first 3GPP network, the message indicating that the first 3GPP network supports IP Multimedia Subsystem (IMS) voice based on a packet switching (PS) session; in response to receiving the instruction The first 3GPP network supports the message of the PS session-based IMS voice, and provides the first 3GPP network with the UE that the fallback of the UE to the second 3GPP network using the second RAT is disabled (disabled) instruct.

In another aspect of the present application, there is provided a method performed by a first 3GPP network that uses a first RAT and is communicatively connected to a UE. The method includes the following steps: sending a message to the UE, the message indicating that the first 3GPP network supports PS session-based IMS voice; in response to the first 3GPP network supporting the PS session-based IMS voice, allowing users from IMS registration of the UE; and in response to initiating an incoming call to the UE, an indication that the incoming call will be established in a second 3GPP network using a second RAT is provided.

By reading the following descriptions of specific implementations of the method for preventing the UE from falling back to the traditional network, other aspects and features of the present application will become obvious to those with ordinary knowledge in the technical field.

The following description is for the purpose of explaining the general principle of the present application, and should not be understood in a limiting sense. It should be understood that the embodiments can be implemented in software, hardware, firmware or any combination thereof. When used herein, the terms "including", "containing", "comprising" and/or "having" designate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude the presence or addition of one Or a plurality of other features, integers, steps, operations, elements, components and/or combinations thereof.

Figure 1 is a block diagram of a wireless communication environment according to an embodiment of the present application.

As shown in Figure 1, the wireless communication environment 100 includes a user equipment (UE) 110 and two 3GPP networks 120 and 130.

The UE 110 may be a feature phone, a smart phone, a tablet personal computer (PC), a laptop computer, or any wireless communication device that supports the RAT used by the 3GPP networks 120 and 130. The UE 110 may wirelessly communicate with one or both of the 3GPP networks 120 and 130.

Specifically, the RAT used by the 3GPP network 120 is more advanced than the RAT used by the 3GPP network 130. That is, the 3GPP network 120 is a more advanced network than the 3GPP network 130 (for example, the 3GPP network 120 may be referred to as an advanced network, and the 3GPP network 130 may be referred to as a traditional network).

For example, the 3GPP network 120 may be a 5G network (for example, NR network), and the 3GPP network 130 may be a 4G network (for example, LTE/LTE-A/TD-LTE network) or a 3G network (for example, WCDMA/CDMA-2000/TD-LTE network). SCDMA network) or 2G network (for example, GSM/GPRS/EDGE network).

Specifically, the 3GPP network 120 includes an access network 121 and a core network 122, and the 3GPP network 130 includes an access network 131 and a core network 132. Access networks 121 and 131 are responsible for processing radio signals, terminating wireless protocols, and connecting UE 110 with core networks 122 and 132, respectively. The core networks 122 and 132 are responsible for performing mobility management, network-side authentication, and interacting with public/external networks (for example, the Internet).

The access networks 121 and 131 and the core networks 122 and 132 may each include one or more network nodes for performing the functions. For example, if the 3GPP network 120 is an NR network, the access network 121 may be a next-generation radio access network (NG-RAN) including at least a gNB or a transmission reception point (Transmission Reception Point, TRP), and the core network 122 may be The next-generation core network (NG-CN) including various network functions, including access and mobility functions (AMF), session management functions (Session Management Function, SMF), and policy control functions ( Policy Control Function (PCF), Application Function (AF), Authentication Server Function (AUSF), User Plane Function (UPF) and User Data Management (UDM) , Each of the network functions can be implemented as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtual instance instantiated on an appropriate platform (such as cloud infrastructure)化 function.

AMF provides UE-based authentication, authorization, mobility management, etc. SMF is responsible for session management and assigns Internet Protocol (IP) addresses to UEs. SMF also selects and controls the UPF used for data transmission. If the UE has multiple sessions, different SMFs can be allocated to each session to manage them separately, and it is possible to provide different functions for each session.

AF provides information on the packet flow to the PCF responsible for policy control to support Quality of Service (QoS). The PCF determines the mobility and session management-related strategies based on the information, so that AMF and SMF can operate normally. AUSF stores the data for UE authentication, while UDM stores the UE's subscription data.

For example, if the 3GPP network 130 is an LTE/LTE-A/TD-LTE network, the access network 131 may be an evolved UTRAN including at least an evolved NB (eNB) (for example, a macro eNB, a femto eNB, or a pico eNB) (E-UTRAN), and the core network 132 may be an evolved packet core (Evolved Packet Core, EPC), the EPC includes a home subscriber server (Home Subscriber Server, HSS), a mobility management entity (Mobility Management Entity, MME), Serving Gateway (Serving Gateway, S-GW) and Packet Data Network Gateway (PDN-GW or P-GW).

Alternatively, if the 3GPP network 130 is a WCDMA network, the access network 121 may be a universal terrestrial radio access network (UTRAN), and the core network 122 may be a GPRS core, and the GPRS core includes a home location register (Home Location Register). , HLR), at least one serving GPRS support node (Serving GPRS Support Node, SGSN) and at least one gateway GPRS support node (Gateway GPRS Support Node, GGSN).

More specifically, the 3GPP networks 120 and 130 both support IP Multimedia Subsystem (IMS) voice based on Packet Switching (PS) sessions, and the 3GPP network 120 supports a fallback procedure that is performed to enable the UE 110 to switch from 3GPP The network 120 falls back to the 3GPP network 130 for IP Multimedia Subsystem (IMS) call service. For example, if the 3GPP network 120 is an NR network and the 3GPP network 130 is an LTE network, the fallback process is called Evolved Packet System (EPS) fallback. Although not shown, each of the 3GPP networks 120 and 130 may include an IMS server that may be connected to or provided in the core network 122/132.

However, due to some reasons, the 3GPP network 120 may not be able to natively provide IMS call services to the UE 110. Therefore, the method of this application is introduced to prevent the UE 110 from falling back from the 3GPP network 120 when the UE 110 is performing critical operations. To the 3GPP network 130.

It should be understood that the description of the wireless communication environment 100 is for illustrative purposes only and is not intended to limit the scope of the present application. For example, if the 6G technology supports the fallback of the UE 110 from the 6G network to the 5G network, the 3GPP network 120 may be a 6G network, and the 3GPP network 130 may be a 5G network.

Figure 2 is a block diagram showing UE 110 according to an embodiment of the present application.

The UE 110 may include a wireless transceiver 10, a controller 20, a storage device 30, a display device 40, and an input/output (I/O) device 50.

The wireless transceiver 10 is configured to perform wireless transmission and reception with the access network 121 and/or the access network 131.

Specifically, the wireless transceiver 10 may include a baseband processing device 11, a radio frequency (RF) device 12, and an antenna 13, where the antenna 13 may include one or more antennas for beamforming. The baseband processing device 11 is configured to perform baseband signal processing and control communication between a user identification card (not shown) and the RF device 12. The baseband processing device 11 may include a plurality of hardware components to perform baseband signal processing, including analog-to-digital conversion (ADC)/digital-to-analog conversion (DAC), gain adjustment, modulation/demodulation, encoding/decoding, etc. The RF device 12 may receive RF wireless signals via the antenna 13, convert the received RF wireless signals into baseband signals processed by the baseband processing device 11, or receive baseband signals from the baseband processing device 11 and convert the received baseband signals into RF wireless signals. The signal is then sent through the antenna 13. The RF device 12 may also include a plurality of 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 wave oscillating in the radio frequency of the supported cellular technology, where the radio frequency may be 900MHz, 1900MHz, or 1900MHz used in a 3G (for example, WCDMA) system. 2100MHz, or can be 900MHz, 2100MHz, or 2.6GHz used in 4G (for example, LTE/LTE-A/TD-LTE) systems, or any radio frequency used in 5G (for example, NR) systems (for example, with It depends on the RAT used.

In another embodiment, the wireless transceiver 10 may include a complex group of baseband processing equipment, RF equipment, and antennas, where each group of baseband processing equipment, RF equipment, and antenna is configured to perform wireless transmission and reception using a corresponding RAT.

The controller 20 may 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 calculation functions, controls the wireless transceiver 10 to communicate with the access network 121 and/or the access network 131 wirelessly, enables the storage device 30, and stores data and slaves in the storage device 30 The storage device 30 retrieves data, sends a series of frame data (for example, representing text messages, graphics, images, etc.) to the display device 40, and receives signals from/outputs signals to the I/O device 50.

In particular, the controller 20 coordinates the aforementioned operations of the wireless transceiver 10, the storage device 30, the display device 40, and the I/O device 50 to perform a method for preventing the UE 110 from falling back to the traditional network.

In another embodiment, the controller 20 may be integrated into the baseband processing device 11 to serve as a baseband processor.

As those with ordinary knowledge in the art will understand, the circuit of the controller 20 will generally include a transistor configured to control the operation of the circuit in accordance with the functions and operations described herein. As will be further understood, the specific structure or interconnection of the transistor will usually be determined by a compiler such as a register transfer language (RTL) compiler. The RTL compiler can be operated by the processor on a script that is very similar to assembly language code to compile the script into a form for final circuit layout or manufacturing. Indeed, RTL is well-known for its role and use in facilitating the design of electronic and digital systems.

The storage device 30 is a non-transitory machine-readable storage medium, including a memory such as FLASH memory or non-volatile random access memory (NVRAM), or a magnetic storage device such as a hard disk or tape, an optical disk or Any combination of them is used to store instructions and/or program codes of the operating system, application program, communication protocol and/or the method of the present application (or the method of the present application can be implemented as a part of the communication protocol).

The display device 40 may be a liquid crystal display (LCD), a light emitting diode (LED) display, or an electronic paper display (EPD), etc., for providing a display function. Alternatively, the display device 40 may further include one or a plurality of touch sensors arranged on or below it for sensing the touch, contact or approximate operation of an object such as a finger or a pen.

The I/O device 50 may include one or more buttons, a keyboard, a mouse, a touchpad, a camera, a microphone, and/or a speaker, etc., to be used as a man-machine interface (MMI) to interact with the user, for example, to receive user input and send it to the user Output prompt.

It should be understood that the components described in the embodiment in Figure 2 are for illustrative purposes only and are not intended to limit the scope of the present application. For example, the UE 110 may include more components, such as a power supply or a global positioning system (GPS) device, where the power supply may be a mobile/replaceable battery that supplies power to all other components of the UE 110. The GPS device can provide location information of the UE 110 for use in certain location-based services or applications. Alternatively, UE 110 may include fewer components. For example, the UE 110 may not include the display device 40 and/or the I/O device 50.

Figure 3 is a flowchart showing a method for preventing a UE from falling back to a traditional network according to an embodiment of the present application.

In this embodiment, the method for preventing the UE from falling back to the traditional network is applied to the UE (for example, the UE 110) and executed by the UE. Specifically, the UE is communicatively connected to a first 3GPP network (for example, 3GPP network 120) that uses an advanced RAT (for example, 5G NR).

First, the UE registers with the first 3GPP network by sending a request message to the first 3GPP network (step S310). In one embodiment, the request message may be a registration request (REGISTRATION REQUEST) message.

After step S310, the UE receives a response message from the first 3GPP network, the response message indicating that the first 3GPP network supports IMS voice based on the PS session (step S320). In an embodiment, the response message may be a registration acceptance (REGISTRATION ACCEPT) message.

After step S320, in response to receiving a response message indicating that the first 3GPP network supports PS session-based IMS voice, the UE provides the first 3GPP network that the fallback of the UE to the second 3GPP network using the traditional RAT is disabled (Step S330), the method ends.

In one embodiment, in response to detecting that the IMS voice session is started, the first 3GPP network is provided with an indication that the fallback of the UE to the second 3GPP network using the traditional RAT is disabled. The details of this embodiment will be given in Figure 4 later.

In another embodiment, the first 3GPP network may be provided with an indication that the fallback of the UE to the second 3GPP network using the traditional RAT is disabled when the IMS registration is performed on the first 3GPP network. The details of this embodiment will be given in Figure 5 later.

Fig. 4 is a message sequence diagram showing the method for preventing the UE from falling back to the traditional network according to the embodiment of Fig. 3.

In step S401, the UE 110 sends a registration request message to the core network 122 to register with the 3GPP network 120.

In step S402, the UE 110 receives a registration acceptance message from the core network 122, where the registration acceptance message indicates that the 3GPP network 120 supports IMS voice based on the PS session.

In step S403, the UE 110 and the 3GPP network 120 establish one or more radio bearers to perform key operations.

Specifically, the key operation may be associated with a Low-Latency Communication (LLC) application such as a game application.

In step S404, in response to the UE 110 being configured to be "voice-centric" and the 3GPP network 120 supports PS session-based IMS voice, the UE 110 sends a Session Initiation Protocol (SIP) registration message to the 3GPP network 120 IMS server to register IMS call service.

In step S405, the UE 110 receives a SIP agree (SIP OK) message from the IMS server of the 3GPP network 120 to complete the IMS registration.

In step S406, the UE 110 receives a SIP invite (INVITE) message from the IMS server of the 3GPP network 120, where the SIP invite message indicates an incoming call to the UE 110.

In step S407, the UE sends a SIP 183 message to the IMS server of the 3GPP network 120, where the SIP 183 message includes a Feature-Caps header field, and there is a specific tag in the Feature-Caps header field. To provide an indication that the fallback of the UE 110 to the legacy 3GPP network (for example, the 3GPP network 130) is disabled.

For example, the specific tag may be a "g.3gpp.epsfb-forbid" tag, a "g.3gpp.epsfb-disallow" tag, a "g.3gpp.noepsfb" tag, or a "g.3gpp.ps-fallback-forbid" tag.

In step S408, in response to the 3GPP network 120 being unable to support the PS session-based IMS voice as usual and receiving the SIP 183 message including the indication that the fallback from the UE 110 to the traditional 3GPP network (for example, the 3GPP network 130) is disabled, the 3GPP network The IMS server of 120 rejects the incoming call. For some reasons, the 3GPP network 120 may not be able to support PS session-based IMS voice as usual (ie, EPS fallback is the only option). For example, the IMS server of the 3GPP network 120 is under maintenance when an incoming call to the UE 110 is initiated, or the operator of the 3GPP network 120 may want to use the traditional 3GPP network (for example, the 3GPP network 130) more frequently. IMS service.

In another embodiment, if the 3GPP network 120 locally supports IMS voice based on the PS session when the incoming call to the UE 110 is initiated, the 3GPP network 120 may continue the call establishment process.

FIG. 5 is another message sequence diagram illustrating the method for preventing the UE from falling back to the traditional network according to the embodiment of FIG. 3.

In step S501, the UE 110 sends a registration request message to the core network 122 to register with the 3GPP network 120.

In step S502, the UE 110 receives a registration acceptance message from the core network 122, where the registration acceptance message indicates that the 3GPP network 120 supports IMS voice based on the PS session.

In step S503, the UE 110 and the 3GPP network 120 establish one or more radio bearers to perform key operations.

Specifically, the key operations may be associated with LLC applications (such as game applications).

In step S504, in response to the UE 110 being configured to be "voice-centric" and the 3GPP network 120 supports PS session-based IMS voice, the UE 110 sends a SIP REGISTER message (SIP REGISTER) to the IMS server of the 3GPP network 120 to register the IMS Call service.

Specifically, the SIP registration message includes a contact header field, where there is no or a specific tag in the contact header field to provide the UE 110 with a fallback to the traditional 3GPP network (for example, the 3GPP network 130) Disabled indication.

In one embodiment, the specific tag may be a "g.3gpp.epsfb" tag or a "g.3gpp.ps-fallback" tag, and when such a tag is missing in the contact header field, it instructs the UE 110 to switch to traditional The fallback of the 3GPP network is disabled.

In another embodiment, the specific tag may be a "g.3gpp.epsfb-forbid" tag, a "g.3gpp.epsfb-disallow" tag, a "g.3gpp.noepsfb" tag or a "g.3gpp.ps" tag. -fallback-forbid" tag, and when such a tag exists in the contact header field, it indicates that the fallback of the UE 110 to the traditional 3GPP network is disabled. Please note that if an embodiment including a positive indication in the SIP REGISTER message is applied, the UE 110 may need to re-register for the IMS call service to allow EPS rollback at the end of the key operation.

In step S505, the UE 110 receives a SIP consent (SIP OK) message from the IMS server of the 3GPP network 120 to complete the IMS registration.

In step S506, in response to the 3GPP network 120 being unable to support PS session-based IMS voice as usual and receiving a SIP registration message including an indication that the UE 110 to the traditional 3GPP network (for example, the 3GPP network 130) is disabled, the 3GPP The IMS server of the network 120 rejects the incoming call. For some reasons, the 3GPP network 120 may not be able to support PS session-based IMS voice as usual (ie, EPS fallback is the only option). For example, when the IMS server of the 3GPP network 120 is under maintenance when an incoming call to the UE 110 is initiated, or the operator of the 3GPP network 120 may want to use the IMS service of the traditional 3GPP network (for example, the 3GPP network 130) more frequently .

In another embodiment, if the 3GPP network 120 locally supports IMS voice based on the PS session when the incoming call to the UE 110 is initiated, the 3GPP network 120 may continue the call establishment process.

In view of the foregoing embodiments in Figs. 3 to 5, it will be recognized that the present invention avoids the UE’s fallback from the advanced 3GPP network to the traditional 3GPP by allowing the UE to provide an indication that the fallback of the UE to the traditional 3GPP network is disabled. The internet. Advantageously, the UE can maintain the connection with the advanced 3GPP network to keep key operations in progress without being interrupted by the IMS call that may trigger a fallback to the traditional 3GPP network.

Fig. 6 is a flowchart showing a method for preventing a UE from falling back to a traditional network according to another embodiment of the present application.

In this embodiment, the method for preventing the UE from falling back to the traditional network is applied to and executed by the first 3GPP network (for example, the 3GPP network 120). Specifically, the first 3GPP network is communicatively connected to the UE (for example, UE 110).

First, the first 3GPP network receives a request message from the UE (step S610). In an embodiment, the request message may be a registration request message.

After step S610, the first 3GPP network replies to the UE with a response message indicating that the first 3GPP network supports IMS voice based on the PS session (step S620). In one embodiment, the response message may be a registration acceptance message.

After step S620, in response to the first 3GPP network supporting IMS voice based on the PS session, the first 3GPP network allows IMS registration from the UE (step S630).

After step S630, in response to initiating the incoming call to the UE, the first 3GPP network provides an indication that the incoming call will be established in the second 3GPP network using the traditional RAT (step S640), and then the method ends.

In one embodiment, if the first 3GPP network cannot provide the IMS call service locally for some reasons, the first 3GPP network may provide an indication that the incoming call to the UE will be established in the second 3GPP network. For example, the IMS server of the first 3GPP network is under maintenance when the incoming call to the UE is initiated, or the operator of the first 3GPP network may want to use the IMS service of the second 3GPP network more frequently.

In one embodiment, the UE may be provided with an indication in the SIP message that an incoming call to the UE is to be established in the second 3GPP network. The details of this embodiment will be given in Figure 7 later.

Fig. 7 is a message sequence diagram showing the method for preventing the UE from falling back to the traditional network according to the embodiment of Fig. 6.

In step S701, the core network 122 receives a registration request message from the UE 110.

In step S702, the core network 122 replies to the UE 110 with a registration acceptance message to instruct the 3GPP network 120 to support IMS voice based on the PS session.

In step S703, the UE 110 and the 3GPP network 120 establish one or more radio bearers to perform key operations.

Specifically, the key operations may be associated with LLC applications (such as game applications).

In step S704, in response to the UE 110 being configured to be "voice-centric" and the 3GPP network 120 supports PS session-based IMS voice, the UE 110 sends a SIP registration message to the IMS server of the 3GPP network 120 to register for the IMS call service.

In step S705, the UE 110 receives a SIP consent message from the IMS server of the 3GPP network 120 to complete the IMS registration.

In step S706, the IMS server of the 3GPP network 120 sends a SIP invite message to the UE 110, where the SIP invite message indicates that an incoming call to the UE 110 will be established in the traditional 3GPP network 130.

In step S707, the IMS server of the 3GPP network 120 receives a SIP 403 message from the UE 110, where the SIP 403 message indicates that the UE 110 has rejected the incoming call.

In step S708, in response to receiving the SIP 403 message indicating that the incoming call is rejected, the IMS server of the 3GPP network 120 rejects the incoming call.

In view of the foregoing embodiments of Figures 6 to 7, it will be recognized that this application prevents the UE from changing from the advanced 3GPP network by allowing the advanced 3GPP network to provide an indication that the incoming call to the UE will be established in the traditional 3GPP network. The network falls back to the traditional 3GPP network. Advantageously, the UE can choose to reject the incoming call and maintain the connection with the advanced 3GPP network, so as to keep the ongoing key operations from being interrupted by the IMS incoming call that may trigger a fallback to the traditional 3GPP network.

Although the present application has been described by way of example and according to preferred embodiments, it should be understood that the present application is not limited thereto. Without departing from the scope and spirit of this application, those with ordinary knowledge in the technical field can still make various changes and modifications (for example, this application can also be applied to prevent UEs from falling back from traditional 3GPP networks to advanced 3GPP networks). For example, in the embodiment shown in Figure 3, the first 3GPP network may be a 2G, 3G or 4G network, the second 3GPP network may be a 5G network, and in step S330 In response to receiving an indication that the first 3GPP supports PS session-based IMS voice, an indication indicating that the fallback of the UE to the second 3GPP network using an advanced RAT (for example, 5G NR) is disabled is provided. For example, in the embodiment shown in Figure 6, the first 3GPP network may be a 2G, 3G or 4G network, the second 3GPP network may be a 5G network, and in step S640, the response When an incoming call to the UE is initiated, an indication indicating that the incoming call will be established in a second 3GPP network using an advanced RAT (for example, 5G NR) is provided). Therefore, the scope of this application should be defined and protected by the scope of the attached patent application and its equivalents.

The use of ordinal terms such as "first" and "second" in the scope of the patent application to modify the elements of the patent application does not mean that one element of the patent application has any priority, priority or priority over another element of the patent application. The sequence or the time sequence of actions to perform a method, and is only used as a mark to distinguish an element of a patent application with a specific name from another element with the same name (but using an ordinal number) to distinguish plural elements of the patent application .

100: wireless communication environment 110: user equipment 120, 130: 3GPP network 121, 131: access network 122, 132: core network 10: wireless transceiver 11: Baseband processing equipment 12: RF equipment 13: Antenna 30: storage equipment 20: Controller 40: display device 50: input/output device S310, S320, S330, S401, S402, S403, S404, S405, S406, S407, S408, S501, S502, S503, S504, S505, S506, S610, S620, S630, S640, S701, S702, S703, S704, S705, S706, S707, S708: steps

By reading the following detailed description and examples with reference to the accompanying drawings, you can have a more comprehensive understanding of this application, in which: Figure 1 is a block diagram of a wireless communication environment according to an embodiment of the present application; Figure 2 is a block diagram showing a UE 110 according to an embodiment of the present application; Figure 3 is a flowchart showing a method for preventing UE from falling back to a traditional network according to an embodiment of the present application; FIG. 4 is a message sequence diagram showing the method for preventing the UE from falling back to the traditional network according to the embodiment of FIG. 3; FIG. 5 is another message sequence diagram showing the method for preventing the UE from falling back to the traditional network according to the embodiment of FIG. 3; FIG. 6 is a flowchart showing a method for preventing UE from falling back to a traditional network according to another embodiment of the present application; and Fig. 7 is a message sequence diagram showing a method for preventing the UE from falling back to the traditional network according to the embodiment of Fig. 6.

S310, S320, S330: steps

Claims (20)

A method for preventing a user equipment from performing network fallback is performed by a user equipment communicatively connected to a first 3GPP network using a first radio access technology, the method comprising: receiving a message from the first 3GPP network, the A message indicating that the first 3GPP network supports IP Multimedia Subsystem voice based on a packet exchange session; and in response to receiving the message indicating that the first 3GPP network supports the IP Multimedia Subsystem voice based on a packet exchange session, When the user equipment supports the fallback to the second 3GPP network using the second radio access technology, the first 3GPP network is provided with the user equipment's return to the second 3GPP network using the second radio access technology. Retire indication that it is disabled. The method according to item 1 of the scope of patent application, wherein in response to detecting that an IP multimedia subsystem voice session is being started, an indication that the fallback of the user equipment to the second 3GPP network is disabled is provided. The method according to item 1 of the scope of patent application, wherein when the IP multimedia subsystem registration is performed on the first 3GPP network, an indication that the fallback of the user equipment to the second 3GPP network is disabled is provided. The method according to item 1 of the scope of patent application, wherein an indication that the fallback of the user equipment to the second 3GPP network is disabled is provided in a session initiation protocol message. The method according to item 4 of the scope of patent application, wherein the session initiation protocol message is a SIP 183 message. The method according to item 5 of the scope of patent application, wherein the SIP 183 message includes a characteristic header field, and the characteristic header field includes a backoff of the user equipment to the second 3GPP network that is disabled instruct. The method according to item 6 of the scope of patent application, wherein the indication that the fallback of the user equipment to the second 3GPP network is disabled refers to "g.3gpp.epsfb-forbid" or "g.3gpp.epsfb-forbid" The "g.3gpp.epsfb-disallow" or "g.3gpp.noepsfb" or "g.3gpp.ps-fallback-forbid" tag exists in the header field of the SIP 183 message. The method according to item 4 of the scope of patent application, wherein the session initiation protocol message is a session initiation protocol registration message. The method according to item 8 of the scope of patent application, wherein the session initiation protocol registration message includes a contact header field, and the contact header field includes the fallback of the user equipment to the second 3GPP network. Disabled indication. According to the method described in item 9 of the scope of patent application, the indication that the fallback of the user equipment to the second 3GPP network is disabled means that there is no "in the contact header field of the session initiation protocol registration message" g.3gpp.epsfb" or "g.3gpp.ps-fallback" label, or refers to the presence of "g.3gpp.epsfb-forbid" or "g.3gpp" in the contact header field of the session initiation protocol registration message .epsfb-disallow" or "g.3gpp.noepsfb" or "g.3gpp.psfb-fallback-forbid" label. The method according to item 1 of the scope of patent application, wherein in response to the use setting of the user equipment is "voice-centric" and a predetermined operation is performed between the user equipment and the first 3GPP network, all An indication that the fallback of the user equipment to the second 3GPP network is disabled. The method according to claim 11, wherein the predetermined operation is associated with a low-latency communication application. The method according to item 1 of the scope of patent application, wherein the message is a registration acceptance message. The method according to item 1 of the scope of patent application, wherein the first radio access technology is a radio access technology that is more advanced than the second radio access technology. A method to prevent user equipment from performing network fallback, executed by the first 3GPP network OK, the first 3GPP network uses a first radio access technology and is communicatively connected to the user equipment, and the method includes: sending a message to the user equipment, the message indicating that the first 3GPP network supports packet-based switching IP Multimedia Subsystem voice of the session; in response to the first 3GPP network supporting the IP Multimedia Subsystem voice based on the packet-switched session, allowing the IP Multimedia Subsystem to register from the user equipment; and in response to the activation of the user equipment Incoming call to provide an indication that the incoming call will be established in the second 3GPP network using the second radio access technology. The method according to item 15 of the scope of patent application, wherein the message is a registration acceptance message. The method according to item 15 of the scope of patent application, wherein an indication that the incoming call is to be established in the second 3GPP network is provided in a session initiation protocol message. The method according to item 17 of the scope of patent application, wherein the session initiation protocol message is a session initiation protocol invitation message. The method according to claim 18, further comprising: receiving a session initiation protocol response message corresponding to the session initiation protocol invitation message from the user equipment, wherein the session initiation protocol response message indicates the incoming call got rejected. The method according to item 19 of the scope of patent application, wherein the session initiation protocol response message is a SIP 403 message.

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