Switching methods, communication equipment, chips, and readable storage media

Abstract

This application proposes a handover method, communication device, chip, and readable storage medium. The method includes: determining that a terminal is undergoing a handover from a first network device to a second network device, wherein the first network device and the second network device are network devices in different systems; sending a first message to the second network device, the first message carrying a first address of the terminal, which is assigned to the terminal by the first network device; and receiving a second message sent by the second network device, the second message carrying a second address of the terminal, which is different from the first address. This ensures that when a handover occurs between different systems and the terminal cannot be assigned its original address by the network, the existing connection will not be directly disconnected. Instead, a new address can be assigned while maintaining the connection, achieving a smooth handover without service interruption, ensuring service continuity, reducing service interruption latency, and effectively improving user experience.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a switching method, communication device, chip, and readable storage medium. Background Technology

[0002] With the continuous development of wireless communication technology, 5G New Radio (NR) is a crucial foundation for the next generation of cellular mobile technology. However, in practical applications, 4G networks are still widely used. With the coexistence of 4G and 5G networks, and the increasing prevalence of 5G, scenarios involving handover between 5G and existing 4G networks will become more frequent. To ensure a superior user experience, higher demands are placed on terminals and networks during inter-system handovers. Summary of the Invention

[0003] This application aims to at least partially address one of the technical problems in the related art.

[0004] Therefore, the following technical solution is proposed:

[0005] A first aspect of this application provides a handover method, the method comprising: determining that a terminal is undergoing a handover from a first network device to a second network device, wherein the first network device and the second network device are network devices of different systems; sending a first message to the second network device, the first message carrying a first address of the terminal, the first address being assigned to the terminal by the first network device; and receiving a second message sent by the second network device, the second message carrying a second address of the terminal, the second address being assigned to the terminal by the second network device, the second address being different from the first address.

[0006] Optionally, the first message is used to request registration from the second network device; the second message is used to indicate that the registration of the terminal is accepted, and the second message is also used to activate the first bearer; wherein, the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0007] Optionally, the method further includes: sending a third message to the second network device, the third message being used to indicate that the registration of the terminal is complete.

[0008] Optionally, the method further includes: releasing a local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, and the second bearer is obtained by mapping based on a third bearer, the third bearer being a bearer on the connection established between the terminal and the first network device.

[0009] Optionally, the first message is a registration request message, and the second message is a registration acceptance message.

[0010] Optionally, the method further includes: sending a fourth message to the second network device, the fourth message being used to instruct the terminal to reject the registration.

[0011] Optionally, the method further includes: deleting a local fourth bearer; wherein the fourth bearer is used by the terminal to send the first message.

[0012] Optionally, the method further includes: sending a registration request message to the second network device, wherein the registration request message is of the initial type.

[0013] Optionally, the first message is used to request the second network device to establish a packet data network (PDN) connection; the second message is used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0014] Optionally, the method further includes: sending a third message to the second network device, the third message being used to instruct the terminal to accept activation of the first bearer.

[0015] Optionally, the method further includes: updating the Internet Protocol (IP) parameters in the relevant module based on the second address.

[0016] Optionally, the method further includes: sending a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse to activate the first bearer; releasing the local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, the second bearer being obtained based on the mapping of a third bearer, the third bearer being a bearer on the connection established between the terminal and the first network device.

[0017] Optionally, the first message is used to request the second network device to establish a Packet Data Unit (PDU) session; the second message is used to indicate that the PDU session establishment request is accepted.

[0018] Optionally, the method further includes: updating the Internet Protocol (IP) parameters in the relevant module based on the second address.

[0019] Optionally, the method further includes: sending a fourth message to the second network device, the fourth message being used to instruct the terminal to end the PDU session; releasing a local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, the second bearer being obtained based on a mapping of a third bearer, the third bearer being a bearer on the connection established between the terminal and the first network device.

[0020] Optionally, the first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

[0021] Optionally, the first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

[0022] A second aspect of this application provides a handover method, the method comprising: receiving a first message sent by a terminal, the first message carrying a first address of the terminal, the first address being assigned to the terminal by a first network device; determining that the first address cannot be assigned to the terminal; sending a second message to the terminal, the second message carrying a second address of the terminal, the second address being different from the first address, the second address being assigned to the terminal by a second network device; wherein the terminal undergoes a handover from the first network device to the second network device, and the first network device and the second network device are network devices from different systems.

[0023] Optionally, the first message is used to request registration from the second network device; the second message is used to indicate that the registration of the terminal is accepted, and the second message is also used to activate the first bearer; wherein, the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0024] Optionally, the method further includes: receiving a third message sent by the terminal, the third message being used to indicate that the registration of the terminal is complete.

[0025] Optionally, the first message is a registration request message, and the second message is a registration acceptance message.

[0026] Optionally, the method further includes: receiving a fourth message sent by the terminal, the fourth message being used to instruct the terminal to reject the registration.

[0027] Optionally, the method further includes: receiving a registration request message sent by the terminal, wherein the registration request message is of the initial type.

[0028] Optionally, the first message is used to request the second network device to establish a packet data network (PDN) connection; the second message is used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0029] Optionally, the method further includes: receiving a third message sent by the terminal, the third message being used to instruct the terminal to accept activation of the first bearer.

[0030] Optionally, the second address is also used to update the Internet Protocol (IP) parameters in the terminal's related modules.

[0031] Optionally, the method further includes: receiving a fourth message sent by the terminal, the fourth message being used to instruct the terminal to refuse to activate the first bearer.

[0032] Optionally, the first message is used to request the second network device to establish a Packet Data Unit (PDU) session; the second message is used to indicate that the PDU session establishment request is accepted.

[0033] Optionally, the second address is also used to update the Internet Protocol (IP) parameters in the terminal's related modules.

[0034] Optionally, the method further includes: receiving a fourth message sent by the terminal, the fourth message being used to instruct the terminal to end the PDU session.

[0035] Optionally, the first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

[0036] Optionally, the first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

[0037] A third aspect of this application provides a terminal, comprising: a processing module, configured to determine that the terminal has switched from a first network device to a second network device, wherein the first network device and the second network device are network devices of different systems; a transceiver module, configured to send a first message to the second network device, the first message carrying a first address of the terminal, the first address being assigned to the terminal by the first network device; the transceiver module is further configured to receive a second message sent by the second network device, the second message carrying a second address of the terminal, the second address being assigned to the terminal by the second network device, the second address being different from the first address.

[0038] Optionally, the first message is used to request registration from the second network device; the second message is used to indicate that the registration of the terminal is accepted, and the second message is also used to activate the first bearer; wherein, the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0039] Optionally, the transceiver module is further configured to: send a third message to the second network device, the third message being used to indicate that the terminal's registration is complete.

[0040] Optionally, the processing module is further configured to: release the local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, and the second bearer is obtained by mapping based on a third bearer, the third bearer being a bearer on the connection established between the terminal and the first network device.

[0041] Optionally, the first message is a registration request message, and the second message is a registration acceptance message.

[0042] Optionally, the transceiver module is further configured to: send a fourth message to the second network device, the fourth message being used to instruct the terminal to reject the registration.

[0043] Optionally, the processing module is further configured to: delete the local fourth bearer; wherein the fourth bearer is used by the terminal to send the first message.

[0044] Optionally, the transceiver module is further configured to: send a registration request message to the second network device, wherein the registration request message is of the initial type.

[0045] Optionally, the first message is used to request the second network device to establish a packet data network (PDN) connection; the second message is used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0046] Optionally, the transceiver module is further configured to: send a third message to the second network device, the third message being used to instruct the terminal to accept activation of the first bearer.

[0047] Optionally, the processing module is further configured to: update the Internet Protocol (IP) parameters in the relevant module based on the second address.

[0048] Optionally, the transceiver module is further configured to: send a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse to activate the first bearer; release the local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, the second bearer being obtained based on the mapping of a third bearer, the third bearer being a bearer on the connection established between the terminal and the first network device.

[0049] Optionally, the first message is used to request the second network device to establish a Packet Data Unit (PDU) session; the second message is used to indicate that the PDU session establishment request is accepted.

[0050] Optionally, the processing module is further configured to: update the Internet Protocol (IP) parameters in the relevant module based on the second address.

[0051] Optionally, the transceiver module is further configured to: send a fourth message to the second network device, the fourth message being used to instruct the terminal to end the PDU session; release the local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, the second bearer being obtained based on the mapping of a third bearer, the third bearer being a bearer on the connection established between the terminal and the first network device.

[0052] Optionally, the first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

[0053] Optionally, the first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

[0054] A fourth aspect of this application provides a second network device, comprising: a transceiver module configured to receive a first message sent by a terminal, the first message carrying a first address of the terminal, the first address being assigned to the terminal by a first network device; the transceiver module further configured to determine that the first address cannot be assigned to the terminal, and send a second message to the terminal, the second message carrying a second address of the terminal, the second address being different from the first address, the second address being assigned to the terminal by a second network device; wherein the terminal undergoes a switch from the first network device to the second network device, and the first network device and the second network device are network devices from different systems.

[0055] Optionally, the first message is used to request registration from the second network device; the second message is used to indicate that the registration of the terminal is accepted, and the second message is also used to activate the first bearer; wherein, the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0056] Optionally, the transceiver module is further configured to: receive a third message sent by the terminal, the third message being used to indicate that the terminal's registration is complete.

[0057] Optionally, the first message is a registration request message, and the second message is a registration acceptance message.

[0058] Optionally, the transceiver module is further configured to: receive a fourth message sent by the terminal, the fourth message being used to instruct the terminal to reject the registration.

[0059] Optionally, the transceiver module is further configured to: receive a registration request message sent by the terminal, wherein the registration request message is of the initial type.

[0060] Optionally, the first message is used to request the second network device to establish a packet data network (PDN) connection; the second message is used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0061] Optionally, the transceiver module is further configured to: receive a third message sent by the terminal, the third message being used to instruct the terminal to accept activation of the first bearer.

[0062] Optionally, the second address is also used to update the Internet Protocol (IP) parameters in the terminal's related modules.

[0063] Optionally, the transceiver module is further configured to: receive a fourth message sent by the terminal, the fourth message being used to instruct the terminal to refuse to activate the first bearer.

[0064] Optionally, the first message is used to request the second network device to establish a Packet Data Unit (PDU) session; the second message is used to indicate that the PDU session establishment request is accepted.

[0065] Optionally, the second address is also used to update the Internet Protocol (IP) parameters in the terminal's related modules.

[0066] Optionally, the transceiver module is further configured to: receive a fourth message sent by the terminal, the fourth message being used to instruct the terminal to end the PDU session.

[0067] Optionally, the first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

[0068] Optionally, the first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

[0069] A fifth aspect of this application provides a communication device including one or more processors; the communication device is used to execute the switching method proposed in the first aspect of this application, or to execute the switching method proposed in the second aspect of this application.

[0070] A sixth aspect of this application provides a chip including at least one processor and a communication interface; the communication interface is used to receive signals input to the chip or signals output from the chip, the processor communicates with the communication interface and implements the switching method proposed in the first aspect of this application, or the switching method proposed in the second aspect of this application, through logic circuits or executing code instructions.

[0071] The fifth aspect of this application provides a non-transitory computer-readable storage medium, wherein when the instructions in the storage medium are executed by the processor of a communication device, the communication device is able to execute the switching method proposed in the first aspect of this application, or execute the switching method proposed in the second aspect of this application.

[0072] The technical solution of this application determines that a terminal is switching from a first network device to a second network device, and the first and second network devices are network devices from different systems; sends a first message to the second network device, the first message carrying the terminal's first address, which is assigned to the terminal by the first network device; and receives a second message sent by the second network device, the second message carrying the terminal's second address, which is assigned to the terminal by the second network device and is different from the first address. This ensures that when a switching occurs between different systems, if the terminal cannot be assigned its original address by the switched network device, the existing connection will not be directly disconnected. Instead, a new address can be assigned while maintaining the connection, achieving a smooth switch without service interruption. This guarantees service continuity, reduces service interruption latency, effectively improves user experience, reduces signaling interaction, effectively lowers the probability of anomalies, effectively reduces complexity, and improves terminal stability and system robustness.

[0073] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0074] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0075] Figure 1A This application provides a schematic diagram of the architecture of a communication system.

[0076] Figure 1B-1D This is an interactive diagram illustrating inter-system switching provided in an embodiment of this application;

[0077] Figure 2 A flowchart illustrating a switching method provided in an embodiment of this application;

[0078] Figure 3A A flowchart illustrating a switching method provided in an embodiment of this application;

[0079] Figure 3B An interactive schematic diagram of a switching method provided in an embodiment of this application;

[0080] Figure 4A A flowchart illustrating a switching method provided in an embodiment of this application;

[0081] Figure 4B An interactive schematic diagram of a switching method provided in an embodiment of this application;

[0082] Figure 5A A flowchart illustrating a switching method provided in an embodiment of this application;

[0083] Figure 5B An interactive schematic diagram of a switching method provided in an embodiment of this application;

[0084] Figure 6A A flowchart illustrating a switching method provided in an embodiment of this application;

[0085] Figure 6B An interactive schematic diagram of a switching method provided in an embodiment of this application;

[0086] Figure 7A A flowchart illustrating a switching method provided in an embodiment of this application;

[0087] Figure 7B An interactive schematic diagram of a switching method provided in an embodiment of this application;

[0088] Figure 8A A flowchart illustrating a switching method provided in an embodiment of this application;

[0089] Figure 8B An interactive schematic diagram of a switching method provided in an embodiment of this application;

[0090] Figure 9-15 A flowchart illustrating a switching method provided in an embodiment of this application;

[0091] Figure 16 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application;

[0092] Figure 17 This is a schematic diagram of the structure of a second network device provided in an embodiment of this application;

[0093] Figure 18 A structural block diagram of a communication device provided in an embodiment of this application;

[0094] Figure 19 This is a schematic diagram of a chip system provided in an embodiment of this application. Detailed Implementation

[0095] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0096] This application provides a switching method, a communication device, a chip, and a readable storage medium. In some embodiments, the terms "switching method" and "information processing method," "communication method," etc., can be used interchangeably; the terms "switching device" and "information processing device," "communication device," etc., can be used interchangeably; and the terms "switching system" and "information processing system," "communication system," etc., can be used interchangeably.

[0097] The embodiments described in this application are not exhaustive, but merely illustrative of some embodiments, and are not intended to limit the scope of protection of this application. Unless otherwise specified, each step in a particular embodiment can be implemented as an independent embodiment, and the steps can be arbitrarily combined. For example, a solution after removing some steps in a particular embodiment can also be implemented as an independent embodiment, and the order of the steps in a particular embodiment can be arbitrarily interchanged. Furthermore, the optional implementation methods in a particular embodiment can be arbitrarily combined; moreover, the embodiments can be arbitrarily combined with each other. For example, some or all steps of different embodiments can be arbitrarily combined, and a particular embodiment can be arbitrarily combined with the optional implementation methods of other embodiments.

[0098] In each embodiment of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of the embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0099] The terminology used in the embodiments of this application is for the purpose of describing specific embodiments only and is not intended to limit the scope of this application.

[0100] In the embodiments of this application, unless otherwise stated, elements expressed in the singular form, such as "a," "an," "the," "the above," "the aforementioned," "this," etc., can mean "one and only one," or "one or more," "at least one," etc. For example, when using articles such as "a," "an," "the," etc. in translation, the noun after the article can be understood as either a singular expression or a plural expression.

[0101] In the embodiments of this application, "multiple" refers to two or more.

[0102] In some embodiments, the terms “at least one of”, “one or more”, “a plurality of”, “multiple”, etc., may be used interchangeably.

[0103] In some embodiments, the notation "at least one of A and B", "A and / or B", "A in one case, B in another", "in response to one case A, in response to another case B", etc., may include the following technical solutions depending on the situation: in some embodiments, A (execute A regardless of B); in some embodiments, B (execute B regardless of A); in some embodiments, execution is selected from A and B (A and B are selectively executed); in some embodiments, both A and B are executed. The same applies when there are more branches such as A, B, C, etc.

[0104] In some embodiments, the notation "A or B" may include the following technical solutions, depending on the situation: in some embodiments, A (execution of A regardless of B); in some embodiments, B (execution of B regardless of A); in some embodiments, execution is selected from A and B (A and B are selectively executed). The same applies when there are more branches such as A, B, C, etc.

[0105] The prefixes "first," "second," etc., used in the embodiments of this application are merely for distinguishing different descriptive objects and do not impose restrictions on the position, order, priority, quantity, or content of the descriptive objects. The description of the descriptive objects is found in the claims or the context of the embodiments, and the use of prefixes should not constitute unnecessary restrictions. For example, if the descriptive object is a "field," the ordinal numbers preceding "field" in "first field" and "second field" do not restrict the position or order of the "fields." "First" and "second" do not restrict whether the "fields" they modify are in the same message, nor do they restrict the order of "first field" and "second field." Similarly, if the descriptive object is a "level," the ordinal numbers preceding "level" in "first level" and "second level" do not restrict the priority between "levels." Furthermore, the number of descriptive objects is not limited by ordinal numbers and can be one or more. For example, in "first device," the number of "devices" can be one or more. Furthermore, the objects modified by different prefixes can be the same or different. For example, if the object being described is "device", then "first device" and "second device" can be the same device or different devices, and their types can be the same or different. Similarly, if the object being described is "information", then "first information" and "second information" can be the same information or different information, and their content can be the same or different.

[0106] In some embodiments, “including A,” “containing A,” “for indicating A,” and “carrying A” can be interpreted as directly carrying A or indirectly indicating A.

[0107] In some embodiments, the terms “in response to…”, “in response to determining…”, “in the case of…”, “when…”, “if…”, “if…”, etc., can be used interchangeably.

[0108] In some embodiments, the terms “greater than,” “greater than or equal to,” “not less than,” “more than,” “more than or equal to,” “not less than,” “higher than,” “higher than or equal to,” “not lower than,” and “above” can be used interchangeably, as can the terms “less than,” “less than or equal to,” “not greater than,” “less than,” “less than or equal to,” “not more than,” “lower than,” “lower than or equal to,” “not higher than,” and “below”.

[0109] In some embodiments, the apparatus and device may be interpreted as physical or virtual, and their names are not limited to the names recorded in the embodiments. In some cases, they may also be understood as "equipment", "device", "circuit", "network element", "node", "function", "unit", "section", "system", "network", "chip", "chip system", "entity", "body", etc.

[0110] In some embodiments, "network" can be interpreted as devices included in the network, such as access network devices, core network devices, etc.

[0111] In some embodiments, "access network device (AN device)" may also be referred to as "radio access network device (RAN device)," "base station (BS)," "radio base station," or "fixed station." In some embodiments, it may also be understood as "node," "access point," "transmission point (TP)," "reception point (RP)," "transmission / reception point (TRP)," "panel," "antenna panel," "antenna array," "cell," "macro cell," "small cell," "femto cell," "pico cell," "sector," "cellgroup," "serving cell," "carrier," "component carrier," or "bandwidth part (BWP)," etc.

[0112] In some embodiments, "terminal" or "terminal device" may be referred to as "user equipment (UE)," "user terminal," "Narrowband-Internet of Things (NB-IoT) device," "mobile station (MS)," "mobile terminal (MT)," "subscriber station," "mobile unit," "subscriber unit," "wireless unit," "remote unit," "mobile device," "wireless device," "wireless communication device," "remote device," "mobile subscriber station," "access terminal," "mobile terminal," "wireless terminal," "remote terminal," "handset," "user agent," "mobile client," "client," etc.

[0113] In some embodiments, access network devices, core network devices, or network devices can be replaced by terminals. For example, various embodiments of this application can also be applied to structures that replace communication between access network devices, core network devices, or network devices and terminals with communication between multiple terminals (e.g., device-to-device (D2D), vehicle-to-everything (V2X), etc.). In this case, the structure can also be configured such that the terminal has all or part of the functions of the access network device. Furthermore, terms such as "uplink" and "downlink" can be replaced with terms corresponding to communication between terminals (e.g., "sidelink"). For example, uplink channel, downlink channel, etc., can be replaced with sidelink channel, uplink link, downlink link, etc., can be replaced with sidelink link.

[0114] In some embodiments, the terminal may be replaced by an access network device, a core network device, or a network device. In this case, the access network device, core network device, or network device may also be configured to have all or some of the functions of the terminal.

[0115] In some embodiments, the acquisition of data, information, etc., may comply with the laws and regulations of the country where the location is situated.

[0116] In some embodiments, data, information, etc., may be obtained with the user's consent.

[0117] Furthermore, each element, each row, or each column in the table of this application embodiment can be implemented as an independent embodiment, and any combination of any element, any row, or any column can also be implemented as an independent embodiment.

[0118] Figure 1A This is a schematic diagram of the architecture of a communication system according to an embodiment of this application.

[0119] like Figure 1A As shown, the communication system 100 includes a terminal 101, a first network device 102, and a second network device 103.

[0120] In some embodiments, terminal 101 includes, for example, at least one of the following: mobile phone, wearable device, Internet of Things (IoT) device, narrowband Internet of Things (NB-IoT) device, satellite communication device, car with communication function, smart car, tablet computer, computer with wireless transceiver function, virtual reality (VR) terminal device, augmented reality (AR) terminal device, wireless terminal device in industrial control, wireless terminal device in self-driving, wireless terminal device in remote medical surgery, wireless terminal device in smart grid, wireless terminal device in transportation safety, wireless terminal device in smart city, wireless terminal device in smart home, and red-capped terminal, but is not limited thereto.

[0121] In some embodiments, the first network device 102 and the second network device 103 are, for example, nodes or devices that connect terminals to a wireless network. The network devices may include, but are not limited to, nodes such as satellites or drones in resource-determining networks, evolved Node B (eNB), next-generation eNB (ng-eNB), next-generation Node B (gNB), next-generation RAN node (NG-RAN node), node B (NB), home node B (HNB), home evolved node B (HeNB), wireless backhaul device, radio network controller (RNC), base station controller (BSC), base transceiver station (BTS), base band unit (BBU), mobile switching center, base station in 6G communication systems, open RAN, cloud RAN, base station in other communication systems, and access node in Wi-Fi systems. The core network includes, for example, at least one of the Evolved Packet Core (EPC), 5G Core Network (5GCN), and Next Generation Core (NGC).

[0122] In some embodiments, the technical solutions of this application can be applied to the Open RAN architecture. In this case, the interfaces between or within access network devices involved in the embodiments of this application can be transformed into internal interfaces of Open RAN. The processes and information interactions between these internal interfaces can be implemented by software or programs.

[0123] In some embodiments, the access network device may be composed of a central unit (CU) and a distributed unit (DU). The CU may also be called a control unit. The CU-DU structure can separate the protocol layer of the access network device. Some of the protocol layer functions are centrally controlled by the CU, while the remaining part or all of the protocol layer functions are distributed in the DU and centrally controlled by the CU. However, this is not the only possibility.

[0124] It is understood that the communication system described in the embodiments of this application is for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and does not constitute a limitation on the technical solutions proposed in the embodiments of this application. As those skilled in the art will know, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions proposed in the embodiments of this application are also applicable to similar technical problems.

[0125] The following embodiments of this application can be applied to Figure 1A The communication system 100 shown, or a part thereof, but not limited to it. Figure 1A The entities shown are illustrative; a communication system may include... Figure 1A All or part of the main body, or may include Figure 1A Other entities besides the main body, the number and form of each entity are arbitrary, each entity can be physical or virtual, the connection relationship between the entities is illustrative, the entities can be unconnected or connected, and the connection can be in any way, it can be a direct connection or an indirect connection, it can be a wired connection or a wireless connection.

[0126] The embodiments of this application can be applied to Non-terrestrial Networks (NTN), Long Term Evolution (LTE), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 5G New Radio (NR), Future Radio Access (FRA), New-Radio Access Technology (RAT), New Radio (NR), New Radio Access (NX), Future Generation Radio Access (FX), Global System for Mobile Communications (GSM (registered trademark)), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX, a registered trademark), IEEE 802.20, Ultra-Wideband (UWB), Bluetooth (a registered trademark), Public Land Mobile Network (PLMN), Device-to-Device (D2D) systems, Machine-to-Machine (M2M) systems, Internet of Things (IoT) systems, Narrow Band-IoT (NB-IoT) systems, Vehicle-to-Everything (V2X) systems, systems utilizing other communication methods, and next-generation systems built upon them. Furthermore, multiple systems can be combined (e.g., a combination of LTE or LTE-A with 5G).

[0127] In some embodiments, the first network device 102 and the second network device 103 are network devices in different communication systems. For example, the first network device 102 is a network device in a 5G system and the second network device 103 is a network device in a 4G system; or, the first network device 102 is a network device in a 4G system and the second network device 103 is a network device in a 5G system, etc.

[0128] In some embodiments, terminal 101 can perform inter-system switching between first network device 102 and second network device 103.

[0129] In some embodiments, the first network device 102 and the second network device 103 do not support the N26 interface.

[0130] In some embodiments, such as Figure 1B As shown, terminal 101 completes initial registration on the 5G network (e.g., through the first network device 102) [the terminal sends a registration request, and the network sends a registration accept], and establishes a Packet Data Unit (PDU) session for user services, allocating Internet Address 1 (IP Address 1 (IP, Internet Protocol)) [the terminal sends a PDU session establishment request, and the network sends a PDU session establishment accept, which carries IP Address 1]. In some cases, terminal 101 may switch from 5G to 4G (e.g., through the second network device 103) or reselect. After completing its camping on the 4G network, it can initiate a registration (attach) process, with the registration type being handover. Furthermore, the 4G network can respond to the attach request from terminal 101. In some cases, if the previous IP Address 1 cannot be allocated, the 4G network will reject the attach request. Therefore, terminal 101 needs to re-initiate the initial registration process.

[0131] In some embodiments, such as Figure 1CAs shown, terminal 101 completes initial registration on the 5G network (e.g., via the first network device 102) [the terminal sends a registration request, and the network sends a registration accept], and establishes a Packet Data Unit (PDU) session for the user service, allocating IP Address 1 [the terminal sends a PDU session establishment request, and the network sends a PDU session establishment accept, which carries IP Address 1]. In some cases, terminal 101 may switch from 5G to 4G (e.g., via the second network device 103) or reselect. After completing its camping on the 4G network, it can initiate an attach procedure. After attaching, terminal 101 can further initiate the reconstruction of the previous bearer (by requesting the establishment of a Packet Data Network (PDN) connection), using the context parameters of the PDU session established under the 5G network. In some cases, if the previous IP Address 1 cannot be allocated, the 4G network will reject the terminal's PDN connection establishment request. Subsequently, terminal 101 will release the previous bearer and reactivate it as needed later.

[0132] In some embodiments, such as Figure 1DAs shown, terminal 101 completes initial registration on a 4G network (e.g., via first network device 102) [the terminal sends an initial type registration request (attach request), the network sends an attachment accept, and the terminal sends an attachment complete], and establishes a PDN connection for user services, allocating IP Address 1 [the terminal sends a PDN connectivity request (PDN connectivity request), the network sends an activate default EPS bearer context request (activate default EPS bearer context accept), and the terminal sends an activate default EPS bearer context accept]]. In some cases, terminal 101 may switch from 4G to 5G (e.g., via second network device 103) or reselect, and after completing its camping on the 5G network, it can initiate the 5G registration process. After 5G registration is complete, terminal 101 can further initiate the reconstruction of the previous bearer (by requesting the establishment of a PDU session), using the context parameters of the bearer corresponding to the PDN connection established under the 4G network. In some cases, if the previous IP Address 1 cannot be allocated, the 5G network will reject the terminal's PDU session establishment request. Subsequently, terminal 101 will release the previous bearer and reactivate it later as needed for services.

[0133] Therefore, if a network cannot be assigned a previous IP address after a system switch, the network will refuse terminal registration or bearer reconstruction, resulting in service interruption and poor user experience.

[0134] The switching method, communication device, chip, and readable storage medium of embodiments of this application are described in detail below with reference to the accompanying drawings.

[0135] Figure 2 This is a flowchart illustrating a switching method provided in an embodiment of this application. It should be noted that this method is applied to a terminal.

[0136] like Figure 2 As shown, the switching method may include the following steps:

[0137] Step 201: Determine that the terminal has switched from the first network device to the second network device.

[0138] In some embodiments, the first network device and the second network device are network devices from different systems.

[0139] For example, the first network device is a network device in a 4G system, and the second network device is a network device in a 5G system; or, the first network device is a network device in a 5G system, and the second network device is a network device in a 4G system, and so on.

[0140] In some embodiments, the first network device does not support the N26 interface.

[0141] In some embodiments, the second network device may or may not support the N26 interface.

[0142] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0143] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDN connection or PDU session for the user service and assigns a corresponding first address.

[0144] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0145] Step 202: Send a first message to the second network device, the first message carrying the first address of the terminal.

[0146] The first address mentioned above is the address assigned to the terminal by the first network device.

[0147] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0148] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0149] In some embodiments, the first message described above is used to request registration from the second network device.

[0150] In some embodiments, the first message is used to request the second network device to establish a packet data network (PDN) connection.

[0151] In some embodiments, the first message is used to request the second network device to establish a Packet Data Unit (PDU) session.

[0152] In some embodiments, the first message may also include other parameters, such as Access Point Name (APN), Data Network Name (DNN), etc.

[0153] In some embodiments, the parameters in the first message are obtained based on the context parameters of the PDN connection or PDU session that the terminal and the first network device have previously established.

[0154] Step 203: Receive a second message sent by the second network device, the second message carrying the second address of the terminal.

[0155] Optionally, the second address may be different from the first address.

[0156] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0157] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0158] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0159] In some embodiments, the second message is used to indicate that the terminal's registration has been accepted, and the second message is also used to activate the first bearer.

[0160] In some embodiments, the second message described above is used to activate the first bearer.

[0161] In some embodiments, the second message described above is used to indicate that the PDU session establishment request is accepted.

[0162] In some embodiments, the terms "access network device (AN device)," "radio access network device (RAN device)," "base station (BS)," "radio base station," "fixed station," "node," "access point," "transmission point (TP)," "reception point (RP)," "transmission / reception point (TRP)," "panel," "antenna panel," "antenna array," "cell," "macro cell," "small cell," "femto cell," "pico cell," "sector," "cell group," "serving cell," "carrier," "component carrier," and "bandwidth part (BWP)" can be used interchangeably.

[0163] In some embodiments, the terms "terminal", "terminal device", "user equipment (UE)", "user terminal", "mobile station (MS)", "mobile terminal (MT)", subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriberstation, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, and client can be used interchangeably.

[0164] In some embodiments, access network devices, core network devices, or network devices can be replaced by terminals. For example, various embodiments of this application can also be applied to structures that replace communication between access network devices, core network devices, or network devices and terminals with communication between multiple terminals (e.g., device-to-device (D2D), vehicle-to-everything (V2X), etc.). In this case, the structure can also be configured such that the terminal has all or part of the functions of the access network device. Furthermore, terms such as "uplink" and "downlink" can be replaced with terms corresponding to communication between terminals (e.g., "sidelink"). For example, uplink channel, downlink channel, etc., can be replaced with sidelink channel, uplink link, downlink link, etc., can be replaced with sidelink link.

[0165] In some embodiments, the terminal may be replaced by an access network device, a core network device, or a network device. In this case, the access network device, core network device, or network device may also be configured to have all or some of the functions of the terminal.

[0166] In some embodiments, the names of information, etc., are not limited to the names described in the embodiments. Terms such as "information", "message", "signal", "signaling", "report", "configuration", "indication", "instruction", "command", "channel", "parameter", "domain", "field", "symbol", "symbol", "codebook", "codeword", "codepoint", "bit", "data", "program", and "chip" can be used interchangeably.

[0167] In some embodiments, the terms "uplink", "uplink", and "physical uplink" can be used interchangeably, as can the terms "downlink", "downlink", and "physical downlink", as well as the terms "sidelink", "sidelink", "sidelink communication", "sidelink communication", "direct connection", "direct link", "direct communication", and "direct link communication".

[0168] In some embodiments, the terms “downlink control information (DCI),” “downlink (DL) assignment,” “DL DCI,” “uplink (UL) grant,” and “UL DCI” can be used interchangeably.

[0169] In some embodiments, terms such as "physical downlink shared channel (PDSCH)" and "DL data" can be used interchangeably, as can terms such as "physical uplink shared channel (PUSCH)" and "UL data".

[0170] In some embodiments, the terms “radio”, “wireless”, “radioaccess network (RAN)”, “access network (AN)”, and “RAN-based” can be used interchangeably.

[0171] This application embodiment determines that a terminal is switching from a first network device to a second network device, and the first and second network devices are network devices from different systems; sends a first message to the second network device, the first message carrying the terminal's first address, which is assigned to the terminal by the first network device; and receives a second message sent by the second network device, the second message carrying the terminal's second address, which is different from the first address. This ensures that when a switching occurs between different systems and the terminal cannot be assigned its original address by the second network device, the existing connection is not directly disconnected. Instead, a new address is assigned while maintaining the connection, achieving a smooth switch without service interruption. This guarantees service continuity, reduces service interruption latency, effectively improves user experience, reduces signaling interaction, effectively lowers the probability of anomalies, reduces complexity, and enhances terminal stability and system robustness.

[0172] Figure 3A This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a terminal.

[0173] like Figure 3A As shown, the switching method may include the following steps:

[0174] Step 301: Determine that the terminal has switched from the first network device to the second network device.

[0175] In some embodiments, the first network device and the second network device are network devices from different systems.

[0176] In this embodiment, the first network device is a network device in a 5G system, the second network device is a network device in a 4G system, and so on.

[0177] In some embodiments, the first network device does not support the N26 interface.

[0178] In some embodiments, the second network device may or may not support the N26 interface.

[0179] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0180] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDU session for the user service and assigns a corresponding first address.

[0181] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0182] Step 302: Send a first message to the second network device. The first message is used to request registration from the second network device and carries the first address of the terminal.

[0183] In some embodiments, the first message described above is used to request registration in the form of a handover.

[0184] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0185] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0186] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0187] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the Access Point Name (APN), etc.

[0188] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the PDU session established between the terminal and the first network device. For example, the Access Point Name (APN) can be obtained by mapping the context parameter Data Network Name (DNN) of the PDU session.

[0189] In some embodiments, the first message mentioned above is an attachment request.

[0190] Step 303: Receive a second message sent by the second network device. The second message indicates that the registration of the terminal has been accepted. The second message carries the second address of the terminal.

[0191] In some embodiments, the second network device sends a second message to the terminal, the second message being used in response to the first message, indicating that the terminal's registration request is accepted, and the second message carrying a second address assigned to the terminal.

[0192] Optionally, the second address may be different from the first address.

[0193] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0194] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0195] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0196] In some embodiments, the second message described above is also used to activate the first bearer.

[0197] The first bearer mentioned above is the default bearer corresponding to the connection established between the terminal and the second network device.

[0198] In some embodiments, the second message may carry an "activate default EPS bearer context request" to activate the first bearer.

[0199] In some embodiments, the above-mentioned second address is included in the above-mentioned request to activate the default EPS bearer context.

[0200] In some embodiments, the second message may also include other parameters required by the first bearer.

[0201] In some embodiments, the second message described above is an attachment accept.

[0202] Step 304: Send a third message to the second network device, which indicates that the terminal's registration is complete.

[0203] In some embodiments, the terminal can send a third message to the second network device, the third message being used to indicate that the terminal's registration is complete.

[0204] In some embodiments, the third message mentioned above is "attach complete".

[0205] Step 305: Release the local secondary bearer.

[0206] The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer corresponding to the PDU session established between the terminal and the first network device.

[0207] Furthermore, the terminal can re-initiate the establishment of a new PDN connection based on business needs.

[0208] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 3B As shown.

[0209] First, the terminal completed initial registration on the 5G network (the first network device). Figure 3B The terminal sends a registration request, and the first network device sends a registration accept. The first network device does not support N26 interface operations. The first network device establishes a PDU session for the user service, and the network allocates corresponding IP address parameters (IP Address 1). The IP address type can be IPv4 single-stack, IPv6 single-stack, or IPv4v6 dual-stack, and a DNN is allocated, etc. Figure 3B The middle terminal sends a PDU session establishment request, and the first network device sends a PDU session establishment accept, which carries IP Address 1.

[0210] Due to network or terminal issues, a 5G to 4G inter-system handover was triggered. Because the N26 interface is not supported, the 5G PDU session cannot be directly mapped to the 4G PDN bearer. Instead, a new PDN connection is initiated on 4G based on the parameters of the 5G PDN session context. After completing the inter-system handover and camping on the cell, the access layer notifies the non-access stratum (NAS) to register.

[0211] Furthermore, after the registration (attach) is triggered, the NAS will use the parameters mapped from the 5G PDU session as the attach parameters, such as the requested IP address type, APN, etc., and send them to the second network device in a handover type. Figure 3B The middle terminal sends the first message (a handover type registration request), and the second network device responds to the attachment request with an attachment accept message carrying an activation default EPS bearer context request, activating the default bearer. The network will then allocate the necessary IP address and other parameters for the bearer. Figure 3BThe second network device sends a second message (attach accept), which carries an activation request for the default EPS bearer context, including the newly assigned IP address. The terminal can then send a message in response to this attach accept, completing this handover type of attach. Figure 3B The terminal sends a third message (registration complete).

[0212] Normally, the IP address assigned to the default bearer for 4G ATTACH should be consistent with the IP address of the previous 5G PDU session, thus achieving seamless bearer handover between different systems. However, in some anomalies, the IP address assigned by the network during 4G ATTACH may not be consistent with the previous one. In this case, the network does not need to reject the terminal's attach request, but instead continues to respond to the terminal with the changed IP address. When this happens, in order to keep the terminal online and improve the user experience, the terminal will not activate the bearer and thus register (DETACH), but will remain in the registered state.

[0213] Furthermore, since there was a service PDU session in 5G, there should normally be a PDN bearer in 4G as well (the bearer mapped from the 5G PDU session). However, due to the change in IP address, the NAS will release the bearer locally and notify the higher layers. The higher layers can then re-initiate a new PDN connection according to service requirements.

[0214] The handover method of this application embodiment determines that a terminal is switching from a first network device to a second network device; sends a first message to the second network device, the first message being used to request registration from the second network device, the first message carrying a first address of the terminal; receives a second message sent by the second network device, the second message being used to indicate that the terminal's registration has been accepted, the second message carrying a second address of the terminal; sends a third message to the second network device, the third message being used to indicate that the terminal's registration is complete; and releases the local second bearer; enabling the terminal to achieve a smooth handover when switching between systems without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving the stability of the terminal and the robustness of the system.

[0215] Figure 4A This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a terminal.

[0216] like Figure 4A As shown, the switching method may include the following steps:

[0217] Step 401: Determine that the terminal has switched from the first network device to the second network device.

[0218] In some embodiments, the first network device and the second network device are network devices from different systems.

[0219] In this embodiment, the first network device is a network device in a 5G system, the second network device is a network device in a 4G system, and so on.

[0220] In some embodiments, the first network device does not support the N26 interface.

[0221] In some embodiments, the second network device may or may not support the N26 interface.

[0222] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0223] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDU session for the user service and assigns a corresponding first address.

[0224] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0225] Step 402: Send a first message to the second network device. The first message is used to request registration from the second network device and carries the first address of the terminal.

[0226] In some embodiments, the first message described above is used to request registration in the form of a handover.

[0227] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0228] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0229] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0230] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the Access Point Name (APN), etc.

[0231] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the PDU session established between the terminal and the first network device. For example, the Access Point Name (APN) can be obtained by mapping the context parameter Data Network Name (DNN) of the PDU session.

[0232] In some embodiments, the first message mentioned above is an attachment request.

[0233] Step 403: Receive a second message sent by the second network device. The second message indicates that the registration of the terminal has been accepted. The second message carries the second address of the terminal.

[0234] In some embodiments, the second network device sends a second message to the terminal, the second message being used in response to the first message, indicating that the terminal's registration request is accepted, and the second message carrying a second address assigned to the terminal.

[0235] Optionally, the second address may be different from the first address.

[0236] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0237] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0238] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0239] In some embodiments, the second message described above is also used to activate the first bearer.

[0240] The first bearer mentioned above is the default bearer corresponding to the connection established between the terminal and the second network device.

[0241] In some embodiments, the second message may carry an "activate default EPS bearer context request" to activate the first bearer.

[0242] In some embodiments, the above-mentioned second address is included in the above-mentioned request to activate the default EPS bearer context.

[0243] In some embodiments, the second message may also include other parameters required by the first bearer.

[0244] In some embodiments, the second message described above is an attachment accept.

[0245] Step 404: Send a fourth message to the second network device, which instructs the terminal to refuse the registration.

[0246] In some embodiments, the terminal can send a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse the registration.

[0247] Optionally, if the terminal rejects the registration, it can trigger the detach process.

[0248] In some embodiments, after receiving a registration acceptance message from a second network device carrying a new address, the terminal may refuse the registration. Furthermore, the terminal may delete the local bearer used to initiate the attach process.

[0249] Furthermore, the terminal can re-initiate the initial attach process later.

[0250] Specifically, the terminal can send an initial type attachment request message to the second network device to initiate the initial attachment process.

[0251] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 4B As shown.

[0252] First, the terminal completed initial registration on the 5G network (the first network device). Figure 4B The terminal sends a registration request, and the first network device sends a registration accept. The first network device does not support N26 interface operations. The first network device establishes a PDU session for the user service, and the network allocates corresponding IP address parameters (IP Address 1). The IP address type can be IPv4 single-stack, IPv6 single-stack, or IPv4v6 dual-stack, and a DNN is allocated, etc. Figure 4B The middle terminal sends a PDU session establishment request, and the first network device sends a PDU session establishment accept, which carries IP Address 1.

[0253] Due to network or terminal issues, a 5G to 4G inter-system handover was triggered. Because the N26 interface is not supported, the 5G PDU session cannot be directly mapped to the 4G PDN bearer. Instead, a new PDN connection is initiated on 4G based on the parameters of the 5G PDN session context. After completing the inter-system handover and camping on the cell, the access layer notifies the non-access stratum (NAS) to register.

[0254] Furthermore, after the registration (attach) is triggered, the NAS will use the parameters mapped from the 5G PDU session as the attach parameters, such as the requested IP address type, APN, etc., and send them to the second network device in a handover type. Figure 4B The middle terminal sends the first message (a handover type registration request), and the second network device responds to the attachment request with an attachment accept message carrying an activation default EPS bearer context request, activating the default bearer. The network will then allocate the necessary IP address and other parameters for the bearer. Figure 4B The second network device sends a second message (attach accept), which carries an activation default EPS bearer context request, including the newly assigned IP address 2.

[0255] Under normal circumstances, the IP address assigned to the default bearer of ATTACH under 4G should be consistent with the IP address of the previous 5G PDU session, so as to achieve seamless handover of bearers between different systems. However, in some abnormal situations, the IP address assigned by the network during 4G ATTACH may not be consistent with the previous one. In this case, the network does not need to reject the terminal's attach request, but will continue to respond to the terminal with the changed IP address.

[0256] In this case, the terminal can reject the handover type of attachment. Figure 4B [The terminal sends the fourth message], triggering the detach process. Furthermore, it can delete the bearer locally and then re-initiate the initial attach process.

[0257] The handover method of this application embodiment determines that a terminal is switching from a first network device to a second network device; sends a first message to the second network device, the first message being used to request registration from the second network device, the first message carrying a first address of the terminal; receives a second message sent by the second network device, the second message being used to indicate that the terminal's registration is accepted, the second message carrying a second address of the terminal; and sends a fourth message to the second network device, the fourth message being used to indicate that the terminal rejects the registration; this enables the terminal to achieve a smooth handover when switching between different systems, reduces service interruption latency, effectively improves user experience, reduces signaling interaction, effectively reduces the probability of anomalies, effectively reduces complexity, and improves the stability of the terminal and the robustness of the system.

[0258] Figure 5A This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a terminal.

[0259] like Figure 5A As shown, the switching method may include the following steps:

[0260] Step 501: Determine that the terminal has switched from the first network device to the second network device.

[0261] In some embodiments, the first network device and the second network device are network devices from different systems.

[0262] In this embodiment, the first network device is a network device in a 5G system, the second network device is a network device in a 4G system, and so on.

[0263] In some embodiments, the first network device does not support the N26 interface.

[0264] In some embodiments, the second network device may or may not support the N26 interface.

[0265] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0266] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDU session for the user service and assigns a corresponding first address.

[0267] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0268] Step 502: Send a first message to the second network device. The first message is used to request the establishment of a PDN connection from the second network device. The first message carries the first address of the terminal.

[0269] In some embodiments, the first message is used to request the establishment of a PDN connection from the second network device.

[0270] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0271] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0272] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0273] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the Access Point Name (APN), etc.

[0274] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the PDU session established between the terminal and the first network device. For example, the Access Point Name (APN) can be obtained by mapping the context parameter Data Network Name (DNN) of the PDU session.

[0275] In some embodiments, the first message mentioned above is a PDN connectivity request.

[0276] In some embodiments, the terminal completes the attachment process before sending the first message mentioned above, and the type of registration is handover.

[0277] Step 503: Receive a second message sent by the second network device. The second message is used to activate the first bearer and carries the second address of the terminal.

[0278] In some embodiments, the second network device sends a second message to the terminal. This second message is a response to the first message and requests activation of a first bearer on the PDN connection. The second message carries a second address allocated to the terminal. The first bearer is the default bearer corresponding to the connection established between the terminal and the second network device.

[0279] Optionally, the second address may be different from the first address.

[0280] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0281] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0282] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0283] In some embodiments, the second message described above may be an activation default EPS bearer context request.

[0284] In some embodiments, the above-mentioned second address is included in the above-mentioned request to activate the default EPS bearer context.

[0285] In some embodiments, the second message may also include other parameters required by the first bearer.

[0286] Step 504: Send a third message to the second network device, which instructs the terminal to accept the activation of the first bearer.

[0287] In some embodiments, the terminal can send a third message to the second network device, the third message being used to instruct the terminal to accept activation of the first bearer.

[0288] In some embodiments, the third message mentioned above is "activatedefault EPS bearer context accept".

[0289] Step 505: Based on the second address, update the IP parameters in the relevant modules.

[0290] In some embodiments, after receiving a second message from a second network device, the terminal can update the IP parameters in relevant modules based on the updated second address carried in the second message. For example, the IP parameters of modules including but not limited to wireless access point (AP) applications and network interface cards (NICs) can be updated.

[0291] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 5B As shown.

[0292] First, the terminal completed initial registration on the 5G network (the first network device). Figure 5BThe terminal sends a registration request, and the first network device sends a registration accept. The first network device does not support N26 interface operations. The first network device establishes a PDU session for the user service, and the network allocates corresponding IP address parameters (IP Address 1). The IP address type can be IPv4 single-stack, IPv6 single-stack, or IPv4v6 dual-stack, and a DNN is allocated, etc. Figure 5B The middle terminal sends a PDU session establishment request, and the first network device sends a PDU session establishment accept, which carries IP Address 1.

[0293] Due to network or terminal issues, a 5G to 4G inter-system handover was triggered. Because the N26 interface is not supported, the 5G PDU session cannot be directly mapped to the 4G PDN bearer. Instead, a new PDN connection is initiated on 4G based on the parameters of the 5G PDN session context. After completing the inter-system handover and camping on the cell, the access layer notifies the non-access stratum (NAS) to register.

[0294] After the terminal completes handover type registration under 4G, Figure 5B The middle terminal sends a handover-type registration request (attach request), the second network device sends an attachment accept, and the terminal sends an attachment complete. Further, the previous bearer needs to be rebuilt and restored. The NAS will use the parameters mapped from the 5GPDU session as the parameters for PDN reconstruction. Figure 5B The middle terminal sends the first message (PDN connectivity request), such as the requested IP address type, APN, etc. The second network device responds with an activatedefaultEPS bearer context request, activating the default bearer. The network will then allocate the necessary IP address and other parameters for the bearer. Figure 5B The second network device sends a second message (activate default EPS bearer context request), which carries the newly assigned IP Address 2.

[0295] Normally, the IP address assigned to the default bearer under 4G should be consistent with the IP address of the previous 5G PDU session to achieve seamless bearer handover between different systems. However, in some anomalies, the IP address assigned by the network in 4G may not be consistent with the previous one. When this happens, in order to keep the bearer active and not affect user services, thus improving the user experience, the network can continue to send the changed IP address to the terminal. The terminal will not activate the bearer itself, but will update the changed IP parameters to the corresponding modules, including but not limited to AP applications and network cards, to maintain the bearer's active state. In this way, the new bearer can continue to be used for the corresponding services without deactivation, maintaining service continuity and avoiding interruptions.

[0296] The handover method of this application embodiment determines that a terminal is switching from a first network device to a second network device; sends a first message to the second network device, the first message being used to request the establishment of a PDN connection, the first message carrying a first address of the terminal; receives a second message sent by the second network device, the second message being used to activate a first bearer, the second message carrying a second address of the terminal; sends a third message to the second network device, the third message being used to instruct the terminal to accept the activation of the first bearer; and updates the IP parameters in relevant modules based on the second address. This enables the terminal to achieve a smooth handover when a cross-system handover occurs, without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving the stability of the terminal and the robustness of the system.

[0297] Figure 6A This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a terminal.

[0298] like Figure 6A As shown, the switching method may include the following steps:

[0299] Step 601: Determine that the terminal has switched from the first network device to the second network device.

[0300] In some embodiments, the first network device and the second network device are network devices from different systems.

[0301] In this embodiment, the first network device is a network device in a 5G system, the second network device is a network device in a 4G system, and so on.

[0302] In some embodiments, the first network device does not support the N26 interface.

[0303] In some embodiments, the second network device may or may not support the N26 interface.

[0304] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0305] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDU session for the user service and assigns a corresponding first address.

[0306] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0307] Step 602: Send a first message to the second network device. The first message is used to request the establishment of a PDN connection from the second network device. The first message carries the first address of the terminal.

[0308] In some embodiments, the first message is used to request the establishment of a PDN connection from the second network device.

[0309] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0310] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0311] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0312] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the Access Point Name (APN), etc.

[0313] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the PDU session established between the terminal and the first network device. For example, the Access Point Name (APN) can be obtained by mapping the context parameter Data Network Name (DNN) of the PDU session.

[0314] In some embodiments, the first message mentioned above is a PDN connectivity request.

[0315] In some embodiments, the terminal completes the attachment process before sending the first message mentioned above, and the type of registration is handover.

[0316] Step 603: Receive a second message sent by the second network device. The second message is used to activate the first bearer and carries the second address of the terminal.

[0317] In some embodiments, the second network device sends a second message to the terminal. This second message is a response to the first message and requests activation of a first bearer on the PDN connection. The second message carries a second address allocated to the terminal. The first bearer is the default bearer corresponding to the connection established between the terminal and the second network device.

[0318] Optionally, the second address may be different from the first address.

[0319] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0320] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0321] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0322] In some embodiments, the second message described above may be an activation default EPS bearer context request.

[0323] In some embodiments, the above-mentioned second address is included in the above-mentioned request to activate the default EPS bearer context.

[0324] In some embodiments, the second message may also include other parameters required by the first bearer.

[0325] Step 604: Send a fourth message to the second network device, which instructs the terminal to refuse to activate the first bearer.

[0326] In some embodiments, the terminal can send a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse to activate the first bearer.

[0327] In some embodiments, after receiving a request from a second network device to activate the default bearer with a changed new address, the terminal may reject the request from the second network device and refuse to activate the default bearer.

[0328] Step 605: Release the local secondary bearer.

[0329] In some embodiments, the terminal is further able to release the local second bearer.

[0330] The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer corresponding to the PDU session established between the terminal and the first network device.

[0331] Furthermore, the terminal can notify the relevant modules to reactivate the bearer based on subsequent business needs.

[0332] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 6B As shown.

[0333] First, the terminal completed initial registration on the 5G network (the first network device). Figure 6B The terminal sends a registration request, and the first network device sends a registration accept. The first network device does not support N26 interface operations. The first network device establishes a PDU session for the user service, and the network allocates corresponding IP address parameters (IP Address 1). The IP address type can be IPv4 single-stack, IPv6 single-stack, or IPv4v6 dual-stack, and a DNN is allocated, etc. Figure 6B The middle terminal sends a PDU session establishment request, and the first network device sends a PDU session establishment accept, which carries IP Address 1.

[0334] Due to network or terminal issues, a 5G to 4G inter-system handover was triggered. Because the N26 interface is not supported, the 5G PDU session cannot be directly mapped to the 4G PDN bearer. Instead, a new PDN connection is initiated on 4G based on the parameters of the 5G PDN session context. After completing the inter-system handover and camping on the cell, the access layer notifies the non-access stratum (NAS) to register.

[0335] After the terminal completes handover type registration under 4G, Figure 6BThe middle terminal sends a handover-type registration request (attach request), the second network device sends an attachment accept, and the terminal sends an attachment complete. Further, the previous bearer needs to be rebuilt and restored. The NAS will use the parameters mapped from the 5GPDU session as the parameters for PDN reconstruction. Figure 6B The middle terminal sends the first message (PDN connectivity request), such as the requested IP address type, APN, etc. The second network device responds with an activatedefaultEPS bearer context request, activating the default bearer. The network will then allocate the necessary IP address and other parameters for the bearer. Figure 6B The second network device sends a second message (activate default EPS bearer context request), which carries the newly assigned IP Address 2.

[0336] Normally, the IP address assigned to the default bearer under 4G should be consistent with the IP address of the previous 5G PDU session to achieve seamless bearer handover between different systems. However, in some anomalies, the IP address assigned by the network in 4G may not be consistent with the previous one. When this happens, in order to keep the bearer active, not affect user services, and improve user experience, the network can continue to send the changed IP address to the terminal. In some cases, after receiving the bearer activation request with the changed IP address, the terminal can also reject the network's request. Figure 6B The terminal sends a fourth message (activate default EPS bearer contextreject) to release the bearer locally and notify the relevant modules. The bearer will be reactivated according to business needs in the future.

[0337] The handover method of this application embodiment determines that a terminal is switching from a first network device to a second network device; sends a first message to the second network device, the first message being used to request the establishment of a PDN connection, the first message carrying a first address of the terminal; receives a second message sent by the second network device, the second message being used to activate a first bearer, the second message carrying a second address of the terminal; sends a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse to activate the first bearer; and releases the local second bearer; enabling the terminal to achieve a smooth handover when switching between different systems, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving the stability of the terminal and the robustness of the system.

[0338] Figure 7A This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a terminal.

[0339] like Figure 7A As shown, the switching method may include the following steps:

[0340] Step 701: Determine that the terminal has switched from the first network device to the second network device.

[0341] In some embodiments, the first network device and the second network device are network devices from different systems.

[0342] In this embodiment, the first network device is a network device in a 4G system, the second network device is a network device in a 5G system, and so on.

[0343] In some embodiments, the first network device does not support the N26 interface.

[0344] In some embodiments, the second network device may or may not support the N26 interface.

[0345] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0346] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDN connection and corresponding bearer for the user service, and allocates a corresponding first address.

[0347] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0348] Step 702: Send a first message to the second network device. The first message is used to request the establishment of a PDU session from the second network device. The first message carries the first address of the terminal.

[0349] In some embodiments, the first message is used to request the establishment of a PDU session from the second network device.

[0350] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0351] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0352] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0353] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the data network name (DNN), etc.

[0354] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the bearer corresponding to the PDN connection established between the terminal and the first network device. For example, the data network name (DNN) can be obtained by mapping the access point name (APN) context parameter of the bearer corresponding to the PDN connection.

[0355] In some embodiments, the first message mentioned above is a PDU sessionestablishment request.

[0356] In some embodiments, the terminal completes the registration process before sending the first message mentioned above, and the registration type is handover.

[0357] Step 703: Receive a second message sent by the second network device. The second message is used to indicate that the PDU session establishment request has been accepted. The second message carries the second address of the terminal.

[0358] In some embodiments, the second network device sends a second message to the terminal, the second message being used in response to the first message, indicating that the PDU session establishment request is accepted, and the second message carrying a second address assigned to the terminal.

[0359] Optionally, the second address may be different from the first address.

[0360] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0361] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0362] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0363] In some embodiments, the second message described above may be a PDU sessionestablishment accept.

[0364] In some embodiments, the second message may also include other parameters required for the PDU session reconstruction.

[0365] Step 704: Based on the second address, update the IP parameters in the relevant modules.

[0366] In some embodiments, after receiving a second message from a second network device, the terminal can update the IP parameters in relevant modules based on the updated second address carried in the second message. For example, the IP parameters of modules including but not limited to wireless access point (AP) applications and network interface cards (NICs) can be updated.

[0367] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 7B As shown.

[0368] First, the terminal completed the initial registration on the 4G network. Figure 7B The terminal sends an initial type attach request, the first network device sends attach accept, and the terminal sends attach complete. It does not support N26 operations. Then, a PDN bearer is established for the user service, and the network allocates the corresponding IP address parameters. The IP address type can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack, and an APN is allocated, etc.

[0369] Due to network or terminal issues, a 4G to 5G inter-system handover was triggered. Because the N26 interface is not supported, the 4G PDN default bearer cannot be directly mapped to a 5G PDU session. Instead, a new PDU session is initiated on the 5G network based on the context parameters of the bearer corresponding to the 4G PDN connection. After completing the inter-system handover and camping on the cell, the access layer notifies the non-access stratum (NAS) to register.

[0370] After the terminal completes handover type registration under 5G, Figure 7B The middle terminal sends a registration request, and the first network device sends a registration accept. This requires rebuilding and restoring the previous bearer. The NAS will use the parameters mapped from the 4G PDN bearer as the parameters for PDU session reconstruction. Figure 7B The terminal sends the first message (PDU session establishment request), such as the requested IP address type, APN (DNN), etc. The network responds with PDU session establishment accept, activating the PDU session. The network will then allocate the necessary IP address and other parameters for the bearer. Figure 7B The second network device sends a second message (PDU session establishment accept), which carries the newly assigned IP Address 2.

[0371] Generally, the IP address assigned to a PDU session under 5G should be consistent with the IP address of the default PDN bearer in 4G, enabling seamless handover between different systems. However, in certain anomalies, the IP address assigned by the network in 5G may not be consistent with the previous one. When this happens, to keep the bearer active, avoid impacting user services, and improve user experience, the network can continue to send the changed IP address to the terminal. The terminal will not activate the bearer but will update the changed IP parameters to the corresponding modules, including but not limited to AP applications and network cards, maintaining the bearer's active state. In this way, the new bearer can continue to be used for the corresponding services without deactivation, maintaining service continuity and avoiding interruptions.

[0372] The handover method of this application embodiment determines that a terminal is switching from a first network device to a second network device; sends a first message to the second network device, the first message being used to request the establishment of a PDU session, the first message carrying a first address of the terminal; receives a second message sent by the second network device, the second message being used to indicate that the PDU session establishment request is accepted, the second message carrying a second address of the terminal; and updates the IP parameters in relevant modules based on the second address. This enables the terminal to achieve a smooth handover when switching between systems, without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving the stability of the terminal and the robustness of the system.

[0373] Figure 8A This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a terminal.

[0374] like Figure 8A As shown, the switching method may include the following steps:

[0375] Step 801: Determine that the terminal has switched from the first network device to the second network device.

[0376] In some embodiments, the first network device and the second network device are network devices from different systems.

[0377] In this embodiment, the first network device is a network device in a 4G system, the second network device is a network device in a 5G system, and so on.

[0378] In some embodiments, the first network device does not support the N26 interface.

[0379] In some embodiments, the second network device may or may not support the N26 interface.

[0380] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0381] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDN connection and corresponding bearer for the user service, and allocates a corresponding first address.

[0382] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0383] Step 802: Send a first message to the second network device. The first message is used to request the establishment of a PDU session from the second network device. The first message carries the first address of the terminal.

[0384] In some embodiments, the first message is used to request the establishment of a PDU session from the second network device.

[0385] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0386] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0387] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0388] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the data network name (DNN), etc.

[0389] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the bearer corresponding to the PDN connection established between the terminal and the first network device. For example, the data network name (DNN) can be obtained by mapping the access point name (APN) context parameter of the bearer corresponding to the PDN connection.

[0390] In some embodiments, the first message mentioned above is a PDU sessionestablishment request.

[0391] In some embodiments, the terminal completes the registration process before sending the first message mentioned above, and the registration type is handover.

[0392] Step 803: Receive a second message sent by the second network device. The second message indicates that the PDU session establishment request has been accepted. The second message carries the second address of the terminal.

[0393] In some embodiments, the second network device sends a second message to the terminal, the second message being used in response to the first message, indicating that the PDU session establishment request is accepted, and the second message carrying a second address assigned to the terminal.

[0394] Optionally, the second address may be different from the first address.

[0395] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0396] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0397] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0398] In some embodiments, the second message described above may be a PDU sessionestablishment accept.

[0399] In some embodiments, the second message may also include other parameters required for the PDU session reconstruction.

[0400] Step 804: Send a fourth message to the second network device, which instructs the terminal to end the PDU session.

[0401] In some embodiments, the terminal can send a fourth message to the second network device, the fourth message being used to instruct the terminal to end the PDU session.

[0402] In some embodiments, after receiving a PDU session establishment acceptance message from a second network device carrying a changed new address, the terminal may terminate the PDU session, refuse to activate the PDU session, and release the local bearer.

[0403] Step 805: Release the local secondary bearer.

[0404] In some embodiments, the terminal is further able to release the local second bearer.

[0405] The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer corresponding to the PDN connection established between the terminal and the first network device.

[0406] Furthermore, the terminal can notify the relevant modules to reactivate the PDU session according to business needs in the future.

[0407] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 8B As shown.

[0408] First, the terminal completed the initial registration on the 4G network. Figure 8BThe terminal sends an initial type attach request, the first network device sends attach accept, and the terminal sends attach complete. It does not support N26 operations. Then, a PDN bearer is established for the user service, and the network allocates the corresponding IP address parameters. The IP address type can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack, and an APN is allocated, etc.

[0409] Due to network or terminal issues, a 4G to 5G inter-system handover was triggered. Because the N26 interface is not supported, the 4G PDN default bearer cannot be directly mapped to a 5G PDU session. Instead, a new PDU session is initiated on the 5G network based on the context parameters of the bearer corresponding to the 4G PDN connection. After completing the inter-system handover and camping on the cell, the access layer notifies the non-access stratum (NAS) to register.

[0410] After the terminal completes handover type registration under 5G, Figure 8B The middle terminal sends a registration request, and the first network device sends a registration accept. This requires rebuilding and restoring the previous bearer. The NAS will use the parameters mapped from the 4G PDN bearer as the parameters for PDU session reconstruction. Figure 8B The terminal sends the first message (PDU session establishment request), such as the requested IP address type, APN (DNN), etc. The network responds with PDU session establishment accept, activating the PDU session. The network will then allocate the necessary IP address and other parameters for the bearer. Figure 8B The second network device sends a second message (PDU session establishment accept), which carries the newly assigned IP Address 2.

[0411] Generally, the IP address assigned to a 5G PDU session should be consistent with the IP address of the default PDN bearer in 4G, enabling seamless handover between different systems. However, in some anomalies, the IP address assigned by the network in 5G may not remain consistent with the previous one. When this happens, to keep the bearer active, avoid impacting user services, and improve user experience, the network can continue to send the changed IP address to the terminal. In some cases, the terminal can terminate the PDU session, release the bearer locally, and notify the relevant modules to reactivate the PDU session according to service requirements.

[0412] The handover method of this application embodiment determines that a terminal is switching from a first network device to a second network device; sends a first message to the second network device, the first message being used to request the establishment of a PDU session, the first message carrying a first address of the terminal; receives a second message sent by the second network device, the second message being used to indicate that the PDU session establishment request is accepted, the second message carrying a second address of the terminal; and updates the IP parameters in relevant modules based on the second address; enabling the terminal to achieve smooth handover when switching between systems, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving the stability of the terminal and the robustness of the system.

[0413] Figure 9 This is a flowchart illustrating a switching method provided in an embodiment of this application. It should be noted that this method is applied to a second network device.

[0414] like Figure 9 As shown, the switching method may include the following steps:

[0415] Step 901: Receive a first message sent by the terminal, which carries the terminal's first address.

[0416] In this embodiment, the terminal switches from a first network device to a second network device.

[0417] In some embodiments, the first network device and the second network device are network devices from different systems.

[0418] For example, the first network device is a network device in a 4G system, and the second network device is a network device in a 5G system; or, the first network device is a network device in a 5G system, and the second network device is a network device in a 4G system, and so on.

[0419] In some embodiments, the first network device does not support the N26 interface.

[0420] In some embodiments, the second network device may or may not support the N26 interface.

[0421] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0422] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDN connection or PDU session for the user service and assigns a corresponding first address.

[0423] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0424] The first address mentioned above is the address assigned to the terminal by the first network device.

[0425] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0426] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0427] In some embodiments, the first message described above is used to request registration from the second network device.

[0428] In some embodiments, the first message is used to request the second network device to establish a packet data network (PDN) connection.

[0429] In some embodiments, the first message is used to request the second network device to establish a Packet Data Unit (PDU) session.

[0430] In some embodiments, the first message may also include other parameters, such as Access Point Name (APN), Data Network Name (DNN), etc.

[0431] In some embodiments, the parameters in the first message are obtained based on the context parameters of the PDN connection or PDU session that the terminal and the first network device have previously established.

[0432] Step 902: Determine that the first address cannot be assigned to the terminal, and send a second message to the terminal, the second message carrying the terminal's second address.

[0433] Optionally, the second address may be different from the first address.

[0434] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0435] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0436] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0437] In some embodiments, the second message is used to indicate that the terminal's registration has been accepted, and the second message is also used to activate the first bearer.

[0438] In some embodiments, the second message described above is used to activate the first bearer.

[0439] In some embodiments, the second message described above is used to indicate that the PDU session establishment request is accepted.

[0440] This application embodiment receives a first message sent by a terminal, the first message carrying a first address; determines that the first address cannot be assigned to the terminal, and sends a second message to the terminal, the second message carrying a second address, the second address being assigned to the terminal by a second network device, and the second address being different from the first address; thus, when a system handover occurs and the terminal cannot be assigned its original address by the second network device, the existing connection will not be directly disconnected, but a new address can be assigned while maintaining the connection, achieving a smooth handover without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, and also reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving terminal stability and system robustness.

[0441] Figure 10 This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a second network device.

[0442] like Figure 10 As shown, the switching method may include the following steps:

[0443] Step 1001: Receive a first message sent by the terminal. The first message is used to request registration from the second network device. The first message carries the terminal's first address.

[0444] In some embodiments, the first message described above is used to request registration in the form of a handover.

[0445] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0446] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0447] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0448] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the Access Point Name (APN), etc.

[0449] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the PDU session established between the terminal and the first network device. For example, the Access Point Name (APN) can be obtained by mapping the context parameter Data Network Name (DNN) of the PDU session.

[0450] In some embodiments, the first message mentioned above is an attachment request.

[0451] In this embodiment, the terminal switches from a first network device to a second network device.

[0452] In some embodiments, the first network device and the second network device are network devices from different systems.

[0453] For example, the first network device is a network device in a 4G system, and the second network device is a network device in a 5G system; or, the first network device is a network device in a 5G system, and the second network device is a network device in a 4G system, and so on.

[0454] In some embodiments, the first network device does not support the N26 interface.

[0455] In some embodiments, the second network device may or may not support the N26 interface.

[0456] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0457] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDN connection or PDU session for the user service and assigns a corresponding first address.

[0458] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0459] Step 1002: Send a second message to the terminal, which indicates that the terminal’s registration has been accepted. The second message carries the terminal’s second address.

[0460] In some embodiments, the second network device sends a second message to the terminal, the second message being used in response to the first message, indicating that the terminal's registration request is accepted, and the second message carrying a second address assigned to the terminal.

[0461] Optionally, the second address may be different from the first address.

[0462] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0463] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0464] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0465] In some embodiments, the second message described above is also used to activate the first bearer.

[0466] The first bearer mentioned above is the default bearer corresponding to the connection established between the terminal and the second network device.

[0467] In some embodiments, the second message may carry an "activate default EPS bearer context request" to activate the first bearer.

[0468] In some embodiments, the above-mentioned second address is included in the above-mentioned request to activate the default EPS bearer context.

[0469] In some embodiments, the second message may also include other parameters required by the first bearer.

[0470] In some embodiments, the second message described above is an attachment accept.

[0471] Step 1003: Receive a third message sent by the terminal, which indicates that the terminal's registration is complete.

[0472] In some embodiments, the second network device can receive a third message sent by the terminal, the third message being used to indicate that the terminal's registration is complete.

[0473] In some embodiments, the third message mentioned above is "attach complete".

[0474] Optionally, the terminal can release its local second bearer after receiving the aforementioned third message.

[0475] The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer corresponding to the PDU session established between the terminal and the first network device.

[0476] Furthermore, the terminal can re-initiate the establishment of a new PDN connection based on business needs.

[0477] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 3B As shown.

[0478] It should be noted that, regarding Figure 3B The description can be found in any embodiment of this application, and will not be repeated here.

[0479] The switching method of this application embodiment involves receiving a first message sent by a terminal, which requests registration from a second network device and carries a first address of the terminal; sending a second message to the terminal, which indicates that the terminal's registration has been accepted and carries a second address of the terminal; and receiving a third message sent by the terminal, which indicates that the terminal's registration is complete. This ensures that during inter-system switching, if the terminal cannot be assigned its original address by the second network device, the existing connection will not be directly disconnected. Instead, a new address can be assigned while maintaining the connection, achieving a smooth switching without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving terminal stability and system robustness.

[0480] Figure 11 This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a second network device.

[0481] like Figure 11 As shown, the switching method may include the following steps:

[0482] Step 1101: Receive a first message sent by the terminal. The first message is used to request registration from the second network device. The first message carries the terminal's first address.

[0483] Step 1102: Send a second message to the terminal, which indicates that the terminal’s registration has been accepted. The second message carries the terminal’s second address.

[0484] It should be noted that the specific implementation of steps 1101-1102 can be referred to the various embodiments of this application, and will not be repeated here.

[0485] Step 1103: Receive a fourth message sent by the terminal, which instructs the terminal to reject the registration.

[0486] In some embodiments, the second network device can receive a fourth message sent by the terminal, which is used to instruct the terminal to refuse the registration.

[0487] Optionally, if the terminal rejects the registration, it can trigger the detach process.

[0488] In some embodiments, after receiving a registration acceptance message from a second network device carrying a new address, the terminal may refuse the registration. Furthermore, the terminal may delete the local bearer used to initiate the attach process.

[0489] Furthermore, the terminal can re-initiate the initial attach process later.

[0490] Specifically, the terminal can send an initial type attachment request message to the second network device to initiate the initial attachment process.

[0491] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 4B As shown.

[0492] It should be noted that, regarding Figure 4B The description can be found in any embodiment of this application, and will not be repeated here.

[0493] The switching method of this application embodiment involves receiving a first message sent by a terminal, which requests registration from a second network device and carries a first address of the terminal; sending a second message to the terminal, which indicates that the terminal's registration is accepted and carries a second address of the terminal; and receiving a fourth message sent by the terminal, which indicates that the terminal rejects the registration. This allows the terminal to re-establish a connection with the network in a short time when a system switch occurs and the terminal cannot be assigned its original address by the second network device, achieving a smooth switch. This reduces service interruption latency, effectively improves user experience, reduces signaling interaction, effectively lowers the probability of anomalies, reduces complexity, and enhances the stability of the terminal and the robustness of the system.

[0494] Figure 12 This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a second network device.

[0495] like Figure 12 As shown, the switching method may include the following steps:

[0496] Step 1201: Receive a first message sent by the terminal. The first message is used to request the establishment of a PDN connection from the second network device. The first message carries the first address of the terminal.

[0497] In some embodiments, the first message is used to request the establishment of a PDN connection from the second network device.

[0498] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0499] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0500] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0501] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the Access Point Name (APN), etc.

[0502] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the PDU session established between the terminal and the first network device. For example, the Access Point Name (APN) can be obtained by mapping the context parameter Data Network Name (DNN) of the PDU session.

[0503] In some embodiments, the first message mentioned above is a PDN connectivity request.

[0504] In some embodiments, the terminal completes the attachment process before sending the first message mentioned above, and the type of registration is handover.

[0505] In this embodiment, the terminal switches from a first network device to a second network device.

[0506] In some embodiments, the first network device and the second network device are network devices from different systems.

[0507] In this embodiment, the first network device is a network device in a 5G system, the second network device is a network device in a 4G system, and so on.

[0508] In some embodiments, the first network device does not support the N26 interface.

[0509] In some embodiments, the second network device may or may not support the N26 interface.

[0510] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0511] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDU session for the user service and assigns a corresponding first address.

[0512] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0513] Step 1202: Send a second message to the terminal. The second message is used to activate the first bearer and carries the second address of the terminal.

[0514] In some embodiments, the second network device sends a second message to the terminal. This second message is a response to the first message and requests activation of a first bearer on the PDN connection. The second message carries a second address allocated to the terminal. The first bearer is the default bearer corresponding to the connection established between the terminal and the second network device.

[0515] Optionally, the second address may be different from the first address.

[0516] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0517] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0518] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0519] In some embodiments, the second message described above may be an activation default EPS bearer context request.

[0520] In some embodiments, the above-mentioned second address is included in the above-mentioned request to activate the default EPS bearer context.

[0521] In some embodiments, the second message may also include other parameters required by the first bearer.

[0522] Step 1203: Receive a third message sent by the terminal, which is used to instruct the terminal to accept the activation of the first bearer.

[0523] In some embodiments, the second network device can receive a third message sent by the terminal, the third message being used to instruct the terminal to accept activation of the first bearer.

[0524] In some embodiments, the third message mentioned above is "activatedefault EPS bearer context accept".

[0525] In some embodiments, the second address is used to update the IP parameters in the relevant modules of the terminal.

[0526] In some embodiments, after receiving a second message from a second network device, the terminal can update the IP parameters in relevant modules based on the updated second address carried in the second message. For example, the IP parameters of modules including but not limited to wireless access point (AP) applications and network interface cards (NICs) can be updated.

[0527] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 5B As shown.

[0528] It should be noted that, regarding Figure 5BThe description can be found in any embodiment of this application, and will not be repeated here.

[0529] The handover method of this application embodiment involves receiving a first message sent by a terminal, which requests the establishment of a PDN connection from a second network device and carries a first address of the terminal; sending a second message to the terminal, which activates a first bearer and carries a second address of the terminal; and receiving a third message sent by the terminal, which instructs the terminal to accept the activation of the first bearer. This ensures that during inter-system handover, if the terminal cannot be assigned its original address by the second network device, the existing connection will not be directly disconnected. Instead, a new address can be assigned while maintaining the connection, achieving a smooth handover without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively lowering the probability of anomalies, effectively reducing complexity, and improving terminal stability and system robustness.

[0530] Figure 13 This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a second network device.

[0531] like Figure 13 As shown, the switching method may include the following steps:

[0532] Step 1301: Receive a first message sent by the terminal. The first message is used to request the establishment of a PDN connection from the second network device. The first message carries the first address of the terminal.

[0533] Step 1302: Send a second message to the terminal. The second message is used to activate the first bearer and carries the second address of the terminal.

[0534] It should be noted that the specific implementation of steps 1301-1302 can be referred to the various embodiments of this application, and will not be repeated here.

[0535] Step 1303: Receive a fourth message sent by the terminal, which is used to instruct the terminal to refuse to activate the first bearer.

[0536] In some embodiments, the second network device can receive a fourth message sent by the terminal, the fourth message being used to instruct the terminal to refuse to activate the first bearer.

[0537] In some embodiments, after receiving a request from a second network device to activate the default bearer with a changed new address, the terminal may reject the request from the second network device and refuse to activate the default bearer.

[0538] In some embodiments, after rejecting the request from the second network device, the terminal is further able to release the local second bearer.

[0539] The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer corresponding to the PDU session established between the terminal and the first network device.

[0540] Furthermore, the terminal can notify the relevant modules to reactivate the bearer based on subsequent business needs.

[0541] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 6B As shown.

[0542] It should be noted that, regarding Figure 6B The description can be found in any embodiment of this application, and will not be repeated here.

[0543] The handover method of this application embodiment involves receiving a first message sent by a terminal, which requests the establishment of a PDN connection from a second network device and carries a first address of the terminal; sending a second message to the terminal, which activates a first bearer and carries a second address of the terminal; and receiving a fourth message sent by the terminal, which instructs the terminal to refuse to activate the first bearer. This ensures that during inter-system handover, if the terminal cannot be assigned its original address by the second network device, the existing connection will not be directly disconnected. Instead, a new address can be assigned while maintaining the connection, achieving a smooth handover without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving terminal stability and system robustness.

[0544] Figure 14 This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a second network device.

[0545] like Figure 14 As shown, the switching method may include the following steps:

[0546] Step 1401: Receive a first message sent by the terminal. The first message is used to request the establishment of a PDU session from the second network device. The first message carries the terminal's first address.

[0547] In some embodiments, the first message is used to request the establishment of a PDU session from the second network device.

[0548] In some embodiments, the first address is an address assigned to the terminal by the first network device.

[0549] Optionally, the aforementioned first address is the corresponding IP address parameter allocated by the first network device when establishing a connection and bearing for the user services of the terminal.

[0550] Optionally, the type of the first address can be IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0551] In some embodiments, the first message may also include other parameters, such as the type of the requested address, the data network name (DNN), etc.

[0552] In some embodiments, the parameters in the first message are obtained by mapping the context parameters of the bearer corresponding to the PDN connection established between the terminal and the first network device. For example, the data network name (DNN) can be obtained by mapping the access point name (APN) context parameter of the bearer corresponding to the PDN connection.

[0553] In some embodiments, the first message mentioned above is a PDU sessionestablishment request.

[0554] In some embodiments, the terminal completes the registration process before sending the first message mentioned above, and the registration type is handover.

[0555] In this embodiment, the terminal switches from a first network device to a second network device.

[0556] In some embodiments, the first network device and the second network device are network devices from different systems.

[0557] In this embodiment, the first network device is a network device in a 4G system, the second network device is a network device in a 5G system, and so on.

[0558] In some embodiments, the first network device does not support the N26 interface.

[0559] In some embodiments, the second network device may or may not support the N26 interface.

[0560] In some embodiments, the terminal can determine that a cross-system handover has occurred from a first network device to a second network device.

[0561] In some embodiments, before the handover occurs, the terminal completes initial registration with the first network device, and the first network device establishes a PDN connection and corresponding bearer for the user service, and allocates a corresponding first address.

[0562] In the various embodiments of this application, the reasons for the above-mentioned switching are not limited. The switching can be caused by any reason, such as terminal reasons or network reasons. This application does not limit it here.

[0563] Step 1402: Send a second message to the terminal. The second message indicates that the PDU session establishment request has been accepted. The second message carries the second address of the terminal.

[0564] In some embodiments, the second network device sends a second message to the terminal, the second message being used in response to the first message, indicating that the PDU session establishment request is accepted, and the second message carrying a second address assigned to the terminal.

[0565] Optionally, the second address may be different from the first address.

[0566] In some embodiments, when a terminal switches to a second network device, the second network device may not be able to assign the terminal the previous first address, and therefore will indicate the changed second address to the terminal in a second message.

[0567] Optionally, the second address mentioned above is the corresponding IP address parameter assigned to the terminal by the second network device.

[0568] Optionally, the second address can be of type IPv4 single stack, IPv6 single stack, or IPv4v6 dual stack.

[0569] In some embodiments, the second message described above may be a PDU sessionestablishment accept.

[0570] In some embodiments, the second message may also include other parameters required for the PDU session reconstruction.

[0571] In some embodiments, the second address is used to update IP parameters in the terminal update related modules.

[0572] In some embodiments, after receiving a second message from a second network device, the terminal can update the IP parameters in relevant modules based on the updated second address carried in the second message. For example, the IP parameters of modules including but not limited to wireless access point (AP) applications and network interface cards (NICs) can be updated.

[0573] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 7B As shown.

[0574] It should be noted that, regarding Figure 7B The description can be found in any embodiment of this application, and will not be repeated here.

[0575] The handover method of this application embodiment receives a first message sent by a terminal, which is used to request the establishment of a PDU session from a second network device. The first message carries a first address of the terminal. It then sends a second message to the terminal, which is used to indicate that the PDU session establishment request has been accepted. The second message carries a second address of the terminal. This ensures that when a handover occurs between different systems and the terminal cannot be assigned its original address by the second network device, the existing connection is not directly disconnected. Instead, a new address is assigned while maintaining the connection, achieving a smooth handover without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively lowering the probability of anomalies, effectively reducing complexity, and improving terminal stability and system robustness.

[0576] Figure 15 This is a flowchart illustrating another switching method provided in an embodiment of this application. It should be noted that the above method is applied to a second network device.

[0577] like Figure 15 As shown, the switching method may include the following steps:

[0578] Step 1501: Receive a first message sent by the terminal. The first message is used to request the establishment of a PDU session from the second network device. The first message carries the first address of the terminal.

[0579] Step 1502: Send a second message to the terminal, which indicates that the PDU session establishment request has been accepted. The second message carries the terminal's second address.

[0580] It should be noted that the specific implementation of steps 1501-1502 can be referred to the various embodiments of this application, and will not be repeated here.

[0581] Step 1503: Receive a fourth message sent by the terminal, which instructs the terminal to end the PDU session.

[0582] In some embodiments, the terminal can send a fourth message to the second network device, the fourth message being used to instruct the terminal to end the PDU session.

[0583] In some embodiments, after receiving a PDU session establishment acceptance message from a second network device carrying a changed new address, the terminal may terminate the PDU session, refuse to activate the PDU session, and release the local bearer.

[0584] In some embodiments, after terminating the PDU session, the terminal is further able to release the local second bearer.

[0585] The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer corresponding to the PDN connection established between the terminal and the first network device.

[0586] Furthermore, the terminal can notify the relevant modules to reactivate the PDU session according to business needs in the future.

[0587] As an example, the interaction between the terminal and the first network device and the second network device in this application embodiment can be as follows: Figure 8B As shown.

[0588] It should be noted that, regarding Figure 8B The description can be found in any embodiment of this application, and will not be repeated here.

[0589] The handover method of this application embodiment involves receiving a first message sent by a terminal, which requests the establishment of a PDU session from a second network device and carries a first address of the terminal; sending a second message to the terminal, which indicates that the PDU session establishment request has been accepted and carries a second address of the terminal; and receiving a fourth message sent by the terminal, which instructs the terminal to terminate the PDU session. This ensures that during inter-system handover, if the terminal cannot be assigned its original address by the second network device, the existing connection will not be directly disconnected. Instead, a new address can be assigned while maintaining the connection, achieving a smooth handover without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving terminal stability and system robustness.

[0590] To implement the above embodiments, this application also proposes a terminal.

[0591] Figure 16 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application.

[0592] like Figure 16 As shown, the terminal includes a processing module 1610 and a transceiver module 1620.

[0593] The processing module 1610 is configured to determine that the terminal has switched from a first network device to a second network device, and that the first network device and the second network device are network devices from different systems; the transceiver module 1620 is configured to send a first message to the second network device, the first message carrying a first address of the terminal, the first address being assigned to the terminal by the first network device; the transceiver module 1620 is also configured to receive a second message sent by the second network device, the second message carrying a second address of the terminal, the second address being assigned to the terminal by the second network device, and the second address being different from the first address.

[0594] Optionally, the first message is used to request registration from the second network device; the second message is used to indicate that the registration of the terminal is accepted; the second message is also used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0595] Optionally, the transceiver module 1620 is further configured to: send a third message to the second network device, the third message being used to indicate that the registration of the terminal is complete.

[0596] Optionally, the processing module 1610 is further configured to: release the local second bearer; wherein the second bearer is the bearer on the connection established between the terminal and the second network device, the second bearer is obtained by mapping based on the third bearer, and the third bearer is the bearer on the connection established between the terminal and the first network device.

[0597] Optionally, the first message is a registration request message, and the second message is a registration acceptance message.

[0598] Optionally, the transceiver module 1620 is further configured to: send a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse the registration.

[0599] Optionally, the processing module 1610 is further configured to: delete the local fourth bearer; wherein the fourth bearer is used by the terminal to send the first message.

[0600] Optionally, the transceiver module 1620 is further configured to: send a registration request message to the second network device, wherein the registration request message is of the initial type.

[0601] Optionally, the first message is used to request the second network device to establish a packet data network (PDN) connection; the second message is used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0602] Optionally, the transceiver module 1620 is further configured to: send a third message to the second network device, wherein the third message is used to instruct the terminal to accept the activation of the first bearer.

[0603] Optionally, the processing module 1610 is further configured to: update the Internet Protocol (IP) parameters in the relevant modules based on the second address.

[0604] Optionally, the transceiver module 1620 is further configured to: send a fourth message to the second network device, the fourth message being used to instruct the terminal to refuse to activate the first bearer; release the local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, the second bearer is obtained based on the mapping of the third bearer, and the third bearer is a bearer on the connection established between the terminal and the first network device.

[0605] Optionally, the first message is used to request the establishment of a Packet Data Unit (PDU) session from the second network device; the second message is used to indicate that the PDU session establishment request is accepted.

[0606] Optionally, the processing module 1610 is further configured to: update the Internet Protocol (IP) parameters in the relevant modules based on the second address.

[0607] Optionally, the transceiver module 1620 is further configured to: send a fourth message to the second network device, the fourth message being used to instruct the terminal to end the PDU session; release the local second bearer; wherein the second bearer is a bearer on the connection established between the terminal and the second network device, the second bearer is obtained by mapping based on a third bearer, and the third bearer is a bearer on the connection established between the terminal and the first network device.

[0608] Optionally, the first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

[0609] Optionally, the first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

[0610] The terminal in this embodiment determines that a handover has occurred from a first network device to a second network device, and the first and second network devices are network devices from different systems. It then sends a first message to the second network device, the first message carrying a first address assigned to the terminal by the first network device. Finally, it receives a second message from the second network device, the second message carrying a second address assigned to the terminal by the second network device, and the second address being different from the first address. This ensures that when a handover occurs between different systems and the terminal cannot be assigned its original address by the new network device, the existing connection is not directly disconnected. Instead, a new address is assigned while maintaining the connection, achieving a smooth handover without service interruption. This guarantees service continuity, reduces service interruption latency, effectively improves user experience, reduces signaling interaction, effectively lowers the probability of anomalies, reduces complexity, and enhances terminal stability and system robustness.

[0611] It should be noted that the foregoing explanation of the switching method embodiment applied to the terminal also applies to the terminal of this embodiment, and will not be repeated here.

[0612] To implement the above embodiments, this application also proposes a second network device.

[0613] Figure 17 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application.

[0614] like Figure 17 As shown, the second network device includes a processing module 1710 and a transceiver module 1720.

[0615] The transceiver module 1720 is configured to receive a first message sent by a terminal, the first message carrying a first address of the terminal, which is assigned to the terminal by a first network device; the transceiver module 1720 is also configured to determine that the first address cannot be assigned to the terminal, and send a second message to the terminal, the second message carrying a second address of the terminal, the second address being different from the first address, which is assigned to the terminal by a second network device; wherein the terminal switches from the first network device to the second network device, and the first network device and the second network device are network devices from different systems.

[0616] Optionally, the first message is used to request registration from the second network device; the second message is used to indicate that the registration of the terminal is accepted; the second message is also used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0617] Optionally, the transceiver module 1720 is further configured to: receive a third message sent by the terminal, the third message being used to indicate that the registration of the terminal is complete.

[0618] Optionally, the first message is a registration request message, and the second message is a registration acceptance message.

[0619] Optionally, the transceiver module 1720 is further configured to: receive a fourth message sent by the terminal, the fourth message being used to instruct the terminal to reject the registration.

[0620] Optionally, the transceiver module 1720 is further configured to: receive a registration request message sent by the terminal, wherein the registration request message is of the initial type.

[0621] Optionally, the first message is used to request the second network device to establish a packet data network (PDN) connection; the second message is used to activate the first bearer; wherein the first bearer is the default bearer on the connection established between the terminal and the second network device.

[0622] Optionally, the transceiver module 1720 is further configured to: receive a third message sent by the terminal, wherein the third message is used to instruct the terminal to accept the activation of the first bearer.

[0623] Optionally, the second address can also be used to update the Internet Protocol (IP) parameters in the relevant modules of the terminal.

[0624] Optionally, the transceiver module 1720 is further configured to: receive a fourth message sent by the terminal, wherein the fourth message is used to instruct the terminal to refuse to activate the first bearer.

[0625] Optionally, the first message is used to request the establishment of a Packet Data Unit (PDU) session from the second network device; the second message is used to indicate that the PDU session establishment request is accepted.

[0626] Optionally, the second address can also be used to update the Internet Protocol (IP) parameters in the relevant modules of the terminal.

[0627] Optionally, the transceiver module 1720 is further configured to: receive a fourth message sent by the terminal, the fourth message being used to instruct the terminal to end the PDU session.

[0628] Optionally, the first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

[0629] Optionally, the first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

[0630] The terminal in this embodiment receives a first message sent by another terminal, the first message carrying a first address; if it is determined that the first address cannot be assigned to the terminal, a second message is sent to the terminal, the second message carrying a second address, the second address being assigned to the terminal by a second network device, and the second address being different from the first address; this ensures that when a system switch occurs and the terminal cannot be assigned its original address by the second network device, the existing connection will not be directly disconnected, but a new address can be assigned while maintaining the connection, achieving a smooth switch without service interruption, ensuring service continuity, reducing service interruption latency, effectively improving user experience, and also reducing signaling interaction, effectively reducing the probability of anomalies, effectively reducing complexity, and improving the stability of the terminal and the robustness of the system.

[0631] It should be noted that the foregoing explanation of the handover method embodiment applied to the second network device also applies to the terminal of this embodiment, and will not be repeated here.

[0632] To implement the above embodiments, this application also proposes a communication device, including one or more processors; wherein the communication device is used to perform the aforementioned... Figures 2-8B The switching method proposed in the embodiments.

[0633] To implement the above embodiments, this application also proposes a communication device, including one or more processors; wherein the communication device is used to perform the aforementioned... Figures 9-15 The switching method proposed in the embodiments.

[0634] To implement the above embodiments, this application also provides a chip, including a processor and an interface; the processor is used to read instructions to execute the aforementioned... Figures 2-8B The switching method proposed in the embodiments.

[0635] To implement the above embodiments, this application also provides a chip, including a processor and an interface; the processor is used to read instructions to execute the aforementioned... Figures 9-15 The switching method proposed in the embodiments.

[0636] To implement the above embodiments, this application also provides another chip, including at least one processor and a communication interface; the communication interface is used to receive signals input to the chip or signals output from the chip, and the processor communicates with the communication interface and implements the aforementioned through logic circuits or executed code instructions. Figures 2-8B The switching method proposed in the embodiments.

[0637] To implement the above embodiments, this application also provides another chip, including at least one processor and a communication interface; the communication interface is used to receive signals input to the chip or signals output from the chip, and the processor communicates with the communication interface and implements the aforementioned through logic circuits or executed code instructions. Figures 9-15 The switching method proposed in the embodiments.

[0638] To implement the above embodiments, this application also proposes a non-transitory computer-readable storage medium, wherein the instructions in the storage medium, when executed by the processor of a communication device, enable the communication device to perform the aforementioned actions. Figures 2-8B The switching method proposed in the embodiments.

[0639] To implement the above embodiments, this application also proposes a non-transitory computer-readable storage medium, wherein the instructions in the storage medium, when executed by the processor of a communication device, enable the communication device to perform the aforementioned actions. Figures 9-15 The switching method proposed in the embodiments.

[0640] Figure 18 This is a block diagram illustrating a communication device according to an exemplary embodiment. For example, the communication device 1800 may be a mobile phone, computer, digital broadcasting terminal, messaging device, game console, tablet device, medical device, fitness equipment, personal digital assistant, etc.

[0641] Reference Figure 18 The communication device 1800 may include one or more of the following components: processing component 1802, memory 1804, power component 1806, multimedia component 1808, audio component 1810, input / output (I / O) interface 1812, sensor component 1814, and communication component 1816.

[0642] Processing component 1802 typically controls the overall operation of communication device 1800, such as operations associated with display, telephone calls, data communication, camera operation, and recording operations. Processing component 1802 may include one or more processors 1820 to execute instructions to perform all or part of the steps of the methods described above. Furthermore, processing component 1802 may include one or more modules to facilitate interaction between processing component 1802 and other components. For example, processing component 1802 may include a multimedia module to facilitate interaction between multimedia component 1808 and processing component 1802.

[0643] Memory 1804 is configured to store various types of data to support the operation of communication device 1800. Examples of this data include instructions for any application or method operating on communication device 1800, contact data, phonebook data, messages, pictures, videos, etc. Memory 1804 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0644] Power component 1806 provides power to various components of communication device 1800. Power component 1806 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to communication device 1800.

[0645] Multimedia component 1808 includes a screen that provides an output interface between the communication device 1800 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touchscreen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, swipes, and gestures on the touch panel. The touch sensors may sense not only the boundaries of the touch or swipe action but also the duration and pressure associated with the touch or swipe operation. In some embodiments, multimedia component 1808 includes a front-facing camera and / or a rear-facing camera. When the communication device 1800 is in an operating mode, such as a shooting mode or a video mode, the front-facing camera and / or the rear-facing camera may receive external multimedia data. Each front-facing camera and rear-facing camera may be a fixed optical lens system or have focal length and optical zoom capabilities.

[0646] Audio component 1810 is configured to output and / or input audio signals. For example, audio component 1810 includes a microphone (MIC) configured to receive external audio signals when communication device 1800 is in an operating mode, such as call mode, recording mode, and voice recognition mode. The received audio signals may be further stored in memory 1804 or transmitted via communication component 1816. In some embodiments, audio component 1810 also includes a speaker for outputting audio signals.

[0647] I / O interface 1812 provides an interface between processing component 1802 and peripheral interface modules, such as keyboards, click wheels, buttons, etc. These buttons may include, but are not limited to, home buttons, volume buttons, power buttons, and lock buttons.

[0648] Sensor assembly 1814 includes one or more sensors for providing status assessments of various aspects of communication device 1800. For example, sensor assembly 1814 can detect the on / off state of communication device 1800, the relative positioning of components such as the display and keypad of communication device 1800, changes in the position of communication device 1800 or a component of communication device 1800, the presence or absence of user contact with communication device 1800, the orientation or acceleration / deceleration of communication device 1800, and temperature changes of communication device 1800. Sensor assembly 1814 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. Sensor assembly 1814 may also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, sensor assembly 1814 may also include an accelerometer, gyroscope, magnetometer, pressure sensor, or temperature sensor.

[0649] Communication component 1816 is configured to facilitate wired or wireless communication between communication device 1800 and other devices. Communication device 1800 can access wireless networks based on communication standards, such as WiFi, 4G, or 18G, or combinations thereof. In one exemplary embodiment, communication component 1816 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, communication component 1816 also includes a near-field communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on radio frequency identification (RFID) technology, Infrared Data Association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0650] In an exemplary embodiment, the communication device 1800 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the methods described above.

[0651] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory 1804 including instructions, which can be executed by a processor 1820 of a communication device 1800 to perform the above-described method. For example, the non-transitory computer-readable storage medium may be a ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage device, etc.

[0652] Some embodiments of this application also provide a chip system, such as Figure 19 As shown, the chip system includes at least one processor 1901 and at least one interface circuit 1902. The processor 1901 and the interface circuit 1902 are interconnected via lines. For example, the interface circuit 1902 can be used to receive signals from other devices (e.g., the memory of an electronic device). As another example, the interface circuit 1902 can be used to send signals to other devices (e.g., the processor 1901). Exemplarily, the interface circuit 1902 can read instructions stored in memory and send those instructions to the processor 1901. When the instructions are executed by the processor 1901, the information processing device can perform the steps in the above embodiments. Of course, the chip system may also include other discrete devices, and some embodiments of this application do not specifically limit this.

[0653] In some embodiments of this application, the interface circuit 1902 can obtain data, program instructions and / or information from the internal storage area of ​​the chip system; it can also obtain data, program instructions and / or information from outside the chip system.

[0654] Optionally, the chip system also includes a memory 1903, which is used to store necessary computer programs and data.

[0655] Those skilled in the art will also understand that the various illustrative logical blocks and steps listed in the embodiments of this application can be implemented by electronic hardware, computer software, or a combination of both. Whether such functionality is implemented through hardware or software depends on the specific application and the overall system design requirements. Those skilled in the art can implement the described functionality using various methods for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of this application.

[0656] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0657] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0658] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0659] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0660] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0661] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0662] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0663] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A switching method, characterized in that, The method includes: It is determined that the terminal has switched from the first network device to the second network device, and the first network device and the second network device are network devices from different systems; Send a first message to the second network device, the first message carrying the first address of the terminal, the first address being assigned to the terminal by the first network device; The terminal receives a second message sent by the second network device, the second message carrying a second address of the terminal, the second address being assigned to the terminal by the second network device, and the second address being different from the first address; The method further includes: Release the local secondary bearer; The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer, which is the bearer on the connection established between the terminal and the first network device.

2. The method according to claim 1, characterized in that, The first message is used to request registration from the second network device; The second message is used to indicate that the registration of the terminal has been accepted, and the second message is also used to activate the first bearer; The first bearer is the default bearer on the connection established between the terminal and the second network device.

3. The method according to claim 2, characterized in that, The method further includes: A third message is sent to the second network device, the third message indicating that the terminal's registration is complete.

4. The method according to any one of claims 2-3, characterized in that, The first message is a registration request message, and the second message is a registration acceptance message.

5. The method according to claim 2, characterized in that, The method further includes: A fourth message is sent to the second network device, the fourth message being used to instruct the terminal to reject the registration.

6. The method according to claim 5, characterized in that, The method further includes: Delete the local fourth bearer; The fourth bearer is used by the terminal to send the first message.

7. The method according to claim 6, characterized in that, The method further includes: Send a registration request message to the second network device. The registration request message is of the initial type.

8. The method according to claim 1, characterized in that, The first message is used to request the second network device to establish a packet data network (PDN) connection; The second message is used to activate the first bearer; The first bearer is the default bearer on the connection established between the terminal and the second network device.

9. The method according to claim 8, characterized in that, The method further includes: A third message is sent to the second network device, the third message being used to instruct the terminal to accept the activation of the first bearer.

10. The method according to claim 9, characterized in that, The method further includes: Based on the second address, update the Internet Protocol (IP) parameters in the relevant modules.

11. The method according to claim 8, characterized in that, The method further includes: A fourth message is sent to the second network device, the fourth message being used to instruct the terminal to refuse to activate the first bearer.

12. The method according to claim 1, characterized in that, The first message is used to request the second network device to establish a Packet Data Unit (PDU) session; The second message is used to indicate that the PDU session establishment request has been accepted.

13. The method according to claim 12, characterized in that, The method further includes: Based on the second address, update the Internet Protocol (IP) parameters in the relevant modules.

14. The method according to claim 12, characterized in that, The method further includes: A fourth message is sent to the second network device, the fourth message being used to instruct the terminal to end the PDU session.

15. The method according to any one of claims 2-11, characterized in that, The first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

16. The method according to any one of claims 12-14, characterized in that, The first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

17. A switching method, characterized in that, The method includes: The receiving terminal sends a first message, which carries a first address of the terminal, which is assigned to the terminal by a first network device; If it is determined that the first address cannot be assigned to the terminal, a second message is sent to the terminal. The second message carries a second address of the terminal, which is different from the first address. The second address is assigned to the terminal by a second network device. Wherein, the terminal switches from the first network device to the second network device, and the first network device and the second network device are network devices from different systems; The second bearer is released by the terminal. The second bearer is the bearer on the connection established between the terminal and the second network device. The second bearer is obtained by mapping based on the third bearer. The third bearer is the bearer on the connection established between the terminal and the first network device.

18. The method according to claim 17, characterized in that, The first message is used to request registration from the second network device; The second message is used to indicate that the registration of the terminal has been accepted, and the second message is also used to activate the first bearer; The first bearer is the default bearer on the connection established between the terminal and the second network device.

19. The method according to claim 18, characterized in that, The method further includes: The terminal sends a third message, which indicates that the terminal's registration is complete.

20. The method according to any one of claims 18-19, characterized in that, The first message is a registration request message, and the second message is a registration acceptance message.

21. The method according to claim 18, characterized in that, The method further includes: The terminal receives a fourth message, which instructs the terminal to reject the registration.

22. The method according to claim 21, characterized in that, The method further includes: Receive a registration request message sent by the terminal, wherein the registration request message is of the initial type.

23. The method according to claim 17, characterized in that, The first message is used to request the second network device to establish a packet data network (PDN) connection; The second message is used to activate the first bearer; The first bearer is the default bearer on the connection established between the terminal and the second network device.

24. The method according to claim 23, characterized in that, The method further includes: The terminal receives a third message, which instructs the terminal to accept activation of the first bearer.

25. The method according to claim 24, characterized in that, The second address is also used to update the Internet Protocol (IP) parameters in the relevant modules of the terminal.

26. The method according to claim 23, characterized in that, The method further includes: The terminal receives a fourth message, which instructs the terminal to refuse to activate the first bearer.

27. The method according to claim 17, characterized in that, The first message is used to request the second network device to establish a Packet Data Unit (PDU) session; The second message is used to indicate that the PDU session establishment request has been accepted.

28. The method according to claim 27, characterized in that, The second address is also used to update the Internet Protocol (IP) parameters in the relevant modules of the terminal.

29. The method according to claim 27, characterized in that, The method further includes: The terminal receives a fourth message, which instructs the terminal to end the PDU session.

30. The method according to any one of claims 18-26, characterized in that, The first network device is a network device in a fifth-generation mobile communication system, and the second network device is a network device in a fourth-generation mobile communication system.

31. The method according to any one of claims 27-29, characterized in that, The first network device is a network device in a fourth-generation mobile communication system, and the second network device is a network device in a fifth-generation mobile communication system.

32. A terminal, characterized in that, The terminal includes: The processing module is used to determine that the terminal has switched from a first network device to a second network device, and that the first network device and the second network device are network devices from different systems. The transceiver module is used to send a first message to the second network device, the first message carrying a first address of the terminal, the first address being assigned to the terminal by the first network device; The transceiver module is further configured to receive a second message sent by the second network device, the second message carrying a second address of the terminal, the second address being assigned to the terminal by the second network device, and the second address being different from the first address; The processing module is also used to release the local second bearer; wherein the second bearer is the bearer on the connection established between the terminal and the second network device, and the second bearer is obtained by mapping based on the third bearer, which is the bearer on the connection established between the terminal and the first network device.

33. A second network device, characterized in that, The second network device includes: The transceiver module is used to receive a first message sent by the terminal, the first message carrying the first address of the terminal, the first address being assigned to the terminal by a first network device; The transceiver module is further configured to determine that the first address cannot be assigned to the terminal, and send a second message to the terminal, the second message carrying a second address of the terminal, the second address being different from the first address, the second address being assigned to the terminal by a second network device; Wherein, the terminal switches from the first network device to the second network device, and the first network device and the second network device are network devices from different systems; wherein, the second bearer is released by the terminal; wherein, the second bearer is the bearer on the connection established between the terminal and the second network device, and the second bearer is obtained by mapping based on the third bearer, and the third bearer is the bearer on the connection established between the terminal and the first network device.

34. A communication device, comprising: One or more processors; The communication device is used to perform the method of any one of claims 1-16, or the method of any one of claims 17-31.

35. A chip, characterized in that, It includes at least one processor and a communication interface; the communication interface is used to receive signals input to the chip or signals output from the chip, the processor communicates with the communication interface and implements the method according to any one of claims 1-16, or the method according to any one of claims 17-31, through logic circuits or executing code instructions.

36. A non-transitory computer-readable storage medium, characterized in that, When the instructions in the storage medium are executed by the processor of the communication device, the communication device is able to perform the method as described in any one of claims 1-16, or the method as described in any one of claims 17-31.

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