WO2025039800A1 - Communication method and apparatus - Google Patents

Abstract

A communication method and apparatus, which are used to ensure the continuity of services when a terminal device moves between coverage areas of different network systems, i.e., a home operator network and a visited operator network. The method comprises: a first mobility management network element receiving a first handover request message from a first access network device, determining to allow a terminal device to switch from a first-standard network in a first operator network to a second-standard network in a second operator network, and sending a second switching request message to a second mobility management network element; and the second mobility management network element sending a third switching request message to a third mobility management network element according to the second switching request message, to request switching of the terminal device from the first-standard network in the first operator network to the second-standard network in the second operator network, wherein the first mobility management network element belongs to the first-standard network in the first operator network, the second mobility management network element belongs to a first-standard network in the second operator network, and the third mobility management network element belongs to the second-standard network in the second operator network.

Description

A communication method and device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on August 22, 2023, with application number 202311062353.X and application name “A Communication Method and Device”, the entire contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of communication technology, and in particular to a communication method and device.

Background Art

The current roaming scenario only supports the continuity of services when the terminal device moves between coverage areas of different network standards (4G coverage area and 5G coverage area) in the visited operator network, but does not support the continuity of services when the terminal device moves between coverage areas of different network standards of the home operator network and the visited operator network. For example, when a terminal device accesses the visited operator network and moves from the 5G coverage area of the visited operator network to the 4G coverage area of the home operator network, the terminal device will disconnect from the visited operator network and re-initiate a registration request to the home operator network during the movement, which will cause service interruption of the terminal device.

Therefore, how to ensure that the terminal device maintains service continuity when moving between the coverage areas of the home operator network and the visited operator network with different network standards is an urgent problem to be solved.

Summary of the invention

The present application provides a communication method and apparatus for ensuring that service continuity is maintained when a terminal device moves between coverage areas of different network standards of a home operator network and a visited operator network.

In a first aspect, the present application provides a communication method, which can be applied to a first mobility management network element, a processor, a chip, a chip system or a functional module of the first mobility management network element. Taking the application to the first mobility management network element as an example, the method may include: the first mobility management network element receives a first switching request message from a first access network device, and according to the first switching request message, determines to allow a terminal device to switch from a first standard network in a first operator network to a second standard network in a second operator network; the first mobility management network element sends a second switching request message to the second mobility management network element. Wherein, the first switching request message is used to request that the terminal device be switched from a first standard network in a first operator network to a second standard network in a second operator network; the first access network device is a shared access network device, and the terminal device accesses the first standard network in the first operator network through the first access network device; the second switching request message is used to request that the terminal device be switched from the first standard network in the first operator network to the second standard network in the second operator network; the first mobility management network element belongs to the first standard network in the first operator network, and the second mobility management network element belongs to the first standard network in the second operator network.

Through the above method, the switching request between different standards initiated by the terminal device in the visited operator network can be converted into two steps: switching between the same standard between the home operator network and the visited operator network and switching between different standards of the home operator network. Subsequently, it can be ensured that the terminal device maintains service continuity when moving between the coverage areas of different network standards of the home operator network and the visited operator network.

In one possible design, the first handover request message may include an identifier of a first public land mobile network (PLMN) currently used by the terminal device, and the first mobile management network element determines, based on the first handover request message, that the terminal device is allowed to switch from the first standard network in the first operator network to the second standard network in the second operator network. The method may be: the first mobile management network element determines that the identifier of the first PLMN is a shared PLMN identifier of the second operator network, and the shared PLMN identifier is used for users of the second operator network to access a shared access network device of the first operator network. In this way, the first mobile management network element can accurately determine that the terminal device is allowed to switch from the first standard network in the first operator network to the second standard network in the second operator network.

In a possible design, the first switching request message may also include an identifier of a target access network device of the terminal device; further, the first mobility management network element may determine an identifier of a second PLMN to which the target access network device belongs based on the identifier of the target access network device, and the second PLMN corresponds to the second operator network .... The first mobile management network element determines that the identifier of the first PLMN is the shared PLMN identifier of the second operator network. The method may be: the first mobile management network element determines that the first PLMN and the second PLMN are equivalent PLMNs according to the identifier of the first PLMN and the identifier of the second PLMN. In this way, the first mobile management network element can determine that the identifier of the first PLMN is the shared PLMN identifier of the second operator network, and further accurately determine that the terminal device is allowed to switch from the first standard network in the first operator network to the second standard network in the second operator network.

In one possible design, the first mobility management network element determines that the first PLMN and the second PLMN are equivalent PLMNs according to the identifier of the first PLMN and the identifier of the second PLMN. The method may be: the first mobility management network element determines that there is an equivalent mapping relationship between the identifier of the first PLMN and the identifier of the second PLMN. In this way, the first mobility management network element accurately determines that the first PLMN and the second PLMN are equivalent PLMNs.

In one possible design, before the first mobility management network element sends the second switching request message to the second mobility management network element, it can generate the second switching request message based on the first switching request message, so that the first mobility management network element sends an accurate second switching request message to the second mobility management network element.

In one possible design, the first mobility management network element generates the second handover request message according to the first handover request message, and the method may be: the first mobility management network element generates the second handover request message, and the second handover request message includes the identifier of the second PLMN and the information in the first handover request message except the identifier of the first PLMN. In this way, the first mobility management network element can accurately determine the second handover request message.

In one possible design, when the first switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from the first standard network to the second standard network, the first mobility management network element sends the second switching request message to the second mobility management network element. In this way, the first mobility management network element can forward the second switching request message to the second mobility management network element in the second operator network.

In one possible design, the second switching request message includes the first switching reason value.

In one possible design, the second handover request message includes first indication information, and the first indication information is used to instruct the second mobility management network element to forward the received handover completion notification message to the first mobility management network element. In this way, the second mobility management network element can subsequently forward the received handover completion notification message to the first mobility management network element.

In a second aspect, the present application provides a communication method, which can be applied to a second mobile management network element, a processor, a chip, a chip system or a functional module of the second mobile management network element. Taking the application to the second mobile management network element as an example, the method may include: the second mobile management network element receives a second switching request message from the first mobile management network element, and sends a third switching request message to the third mobile management network element according to the second switching request message. The second switching request message is used to request that the terminal device be switched from the first standard network in the first operator network to the second standard network in the second operator network; the third switching request message is used to request that the terminal device be switched from the first standard network in the first operator network to the second standard network in the second operator network; the first mobile management network element belongs to the first standard network in the first operator network, the second mobile management network element belongs to the first standard network in the second operator network, and the third mobile management network element belongs to the second standard network in the second operator network.

Through the above method, the switching request between different standards initiated by the terminal device in the visited operator network can be converted into two steps: switching between the same standard between the home operator network and the visited operator network and switching between different standards of the home operator network. Subsequently, it can be ensured that the terminal device maintains service continuity when moving between the coverage areas of different network standards of the home operator network and the visited operator network.

In a possible design, the second mobility management network element sends the third handover request message to the third mobility management network element according to the second handover request message, and the method may be: when the second handover request message includes a first handover reason value, and the first handover reason value is used to indicate that the terminal device switches from the first standard network to the second standard network, the second mobility management network element may send the third handover request message to the third mobility management network element. In this way, the second mobility management network element may select a suitable third mobility management network element according to the first handover reason value, and send the third handover request message to the third mobility management network element.

In a possible design, the second handover request message may include first indication information, and the first indication information is used to instruct the second mobility management network element to send the received handover completion notification message to the first mobility management network element; further, the second mobility management network element receives a handover completion notification message from the third mobility management network element, and the handover completion notification message is used to notify the terminal device that the terminal device has been switched to the second standard network in the second operator network; the second mobility management network element sends the handover completion notification message to the first mobility management network element according to the first indication information. In this way, the first mobility management network element can determine that the terminal device has been switched to the second standard network in the second operator network.

In one possible design, the second switching request message includes an identifier of a second PLMN, and the identifier of the second PLMN is used to identify the PLMN to which the target access network device of the terminal device belongs.

In a third aspect, the present application provides a communication method, which can be applied to a second mobility management network element, a processor, a chip, a chip system or a functional module of the second mobility management network element. Taking the application to the second mobility management network element as an example, the method may include: the second mobility management network element receives a first switching request message from a third mobility management network element, and according to the first switching request message, determines that the target access network device of the terminal device is a shared access network device, and the target access network device is used for the terminal device to access the first operator network; the second mobility management network element sends a second switching request message to the first mobility management network element according to the first switching request message. The first switching request message is used to request that the terminal device be switched from the second standard network in the second operator network to the first standard network in the first operator network; the second switching request message is used to request that the terminal device be switched from the second standard network in the second operator network to the first standard network in the first operator network; the first mobility management network element belongs to the first standard network in the first operator network, the second mobility management network element belongs to the first standard network in the second operator network, and the third mobility management network element belongs to the second standard network in the second operator network.

Through the above method, the switching request between different standards of the terminal device between the home operator network and the visited operator network can be converted into two steps: switching between different standards within the home operator network and switching between the same standard between the home operator network and the visited operator network. This can ensure that the terminal device maintains service continuity when moving between the coverage areas of different network standards of the home operator network and the visited operator network.

In a possible design, the first handover request message may include an identifier of the target access network device; the second mobility management network element determines that the target access network device of the terminal device is a shared access network device according to the first handover request message, and the method may be: the second mobility management network element determines the identifier of the first PLMN to which the target access network device belongs according to the identifier of the target access network device, and the first PLMN corresponds to the first operator network; if the identifier of the first PLMN corresponds to the shared PLMN identifier, the second mobility management network element determines that the target access network device of the terminal device is the shared access network device; wherein the shared PLMN identifier is used for users of the second operator network to access the shared access network device of the first operator network. In this way, the second mobility management network element can accurately determine that the target access network device of the terminal device is a shared access network device.

In one possible design, when the first handover request message includes a second handover reason value, and the second handover reason value is used to indicate that the terminal device switches from the second standard network to the first standard network, the second mobility management network element may send the second handover request message to the first mobility management network element. In this way, the second mobility management network element may forward the second handover request message to the first mobility management network element in the first operator network.

In one possible design, before the second mobility management network element sends the second handover request message to the first mobility management network element, the second handover request message may be generated according to the first handover request message, and the second handover request message includes the shared PLMN identifier and the information included in the first handover request message. In this way, the second mobility management network element can send an accurate second handover request message to the first mobility management network element.

In one possible design, the second handover request message may include second indication information, and the second indication information is used to instruct the first mobility management network element to forward the received handover completion notification message to the second mobility management network element. In this way, the first mobility management network element can subsequently forward the received handover completion notification message to the second mobility management network element.

In a fourth aspect, the present application provides a communication method, which can be applied to a first mobile management network element, a processor, a chip, a chip system or a functional module of the first mobile management network element. Taking the application to the first mobile management network element as an example, the method may include: the first mobile management network element receives a second switching request message from the second mobile management network element, and according to the second switching request message, determines to allow the terminal device to switch from the second standard network in the second operator network to the first standard network in the first operator network; thereafter, the first mobile management network element sends a session establishment request message to the first session management network element according to the second switching request message. The second switching request message is used to request to switch the terminal device from the second standard network in the second operator network to the first standard network in the first operator network; the first mobile management network element belongs to the first standard network in the first operator network, the second mobile management network element belongs to the first standard network in the second operator network, and the first session management network element belongs to the first standard network in the first operator network.

Through the above method, the switching request between different standards of the terminal device between the home operator network and the visited operator network is converted into two steps: switching between different standards within the home operator network and switching between the same standard between the home operator network and the visited operator network. This can ensure that the terminal device maintains service continuity when moving between the coverage areas of different network standards of the home operator network and the visited operator network.

In one possible design, the second handover request message may include a shared PLMN identifier. The first mobile management network element determines, based on the second switching request message, that the terminal device is allowed to switch from the second standard network in the second operator network to the first standard network in the first operator network. The method may be: when the identifier of the second PLMN currently used by the terminal device has an equivalent mapping relationship with the shared PLMN identifier, the first mobile management network element determines that the terminal device is allowed to switch from the second standard network in the second operator network to the first standard network in the first operator network. In this way, the first mobile management network element can accurately determine that the terminal device is allowed to switch from the second standard network in the second operator network to the first standard network in the first operator network.

In a possible design, the second handover request message may include second indication information, and the second indication information is used to instruct the first mobility management network element to forward the received handover completion notification message to the second mobility management network element; further, after receiving the handover completion notification message, the first mobility management network element sends the handover completion notification message to the second mobility management network element according to the second indication information. The handover completion notification message is used to notify the terminal device that it has switched to the first standard network in the first operator network. In this way, the second mobility management network element can determine that the terminal device has switched to the first standard network in the first operator network.

In a fifth aspect, the present application further provides a communication device, which may be a first mobile management network element, and the communication device has the function of implementing the method in the first aspect or each possible design example of the first aspect, or the fourth aspect or each possible design example of the fourth aspect. The function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

In one possible design, the structure of the communication device may include a transceiver unit and a processing unit, which can execute the methods described in the above-mentioned first aspect or various possible design examples of the first aspect, or the above-mentioned fourth aspect or various possible design examples of the fourth aspect, which are not repeated here.

In one possible design, the structure of the communication device includes a memory and a processor. The optional communication device also includes a transceiver, which is used to send and receive data, messages or information, and is used to communicate and interact with other devices in the communication system. The processor is configured to support the communication device to perform the corresponding functions in the first aspect or each possible design example of the first aspect, or in the fourth aspect or each possible design example of the fourth aspect. The memory is coupled to the processor, which stores the computer instructions and data necessary for the communication device.

In a sixth aspect, the present application further provides a communication device, which may be a second mobility management network element, and the communication device has the function of implementing the method in the second aspect or each possible design example of the second aspect, or the third aspect or each possible design example of the third aspect. The function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

In one possible design, the structure of the communication device may include a transceiver unit and a processing unit, which can execute the methods described in the above-mentioned second aspect or various possible design examples of the second aspect, or the above-mentioned third aspect or various possible design examples of the third aspect, which are not repeated here.

In one possible design, the structure of the communication device includes a memory and a processor. The optional communication device also includes a transceiver, which is used to send and receive data, messages or information, and is used to communicate and interact with other devices in the communication system. The processor is configured to support the communication device to perform the corresponding functions in the above-mentioned second aspect or each possible design example of the second aspect, or in the above-mentioned third aspect or each possible design example of the third aspect. The memory is coupled to the processor, which stores the computer instructions and data necessary for the communication device.

In the seventh aspect, an embodiment of the present application provides a communication system, which may include a first mobile management network element and a second mobile management network element, wherein the first mobile management network element may execute the method in the above-mentioned first aspect and any possible design thereof, or the above-mentioned fourth aspect and any possible design thereof; the second mobile management network element is used to execute the method in the above-mentioned second aspect and any possible design thereof, or the above-mentioned third aspect and any possible design thereof.

In an eighth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores instructions. When the instructions are executed on a computer, the computer executes the method described in the first aspect of the embodiment of the present application and any possible design thereof, or the second aspect and any possible design thereof, or the third aspect and any possible design thereof, or the fourth aspect and any possible design thereof. Exemplarily, the computer-readable storage medium can be any available medium that can be accessed by a computer. Taking this as an example but not limited to: a computer-readable medium may include a non-transitory computer-readable medium, a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a CD-ROM or other optical disk storage, a magnetic disk storage medium or other magnetic storage device, or a medium that can be used to carry or store instructions or Any other medium that can store desired program code in the form of data structures and that can be accessed by a computer.

In a ninth aspect, an embodiment of the present application provides a computer program product, comprising instructions, which, when executed on a computer, causes the method described in the first aspect or any possible design of the first aspect, or the second aspect or any possible design of the second aspect, or the third aspect or any possible design of the third aspect, or the fourth aspect or any possible design of the fourth aspect to be executed.

In the tenth aspect, the present application also provides a chip, including a processor, which is coupled to a memory and is used to read and execute instructions stored in the memory, so that the chip implements the method described in the above-mentioned first aspect or any possible design of the first aspect, or the above-mentioned second aspect or any possible design of the second aspect, or the above-mentioned third aspect or any possible design of the third aspect, or the above-mentioned fourth aspect or any possible design of the fourth aspect.

For each of the above-mentioned fifth to tenth aspects and the technical effects that may be achieved by each of the aspects, please refer to the above-mentioned description of the technical effects that can be achieved by the first aspect or the various possible schemes in the first aspect, or the above-mentioned second aspect or the various possible schemes in the second aspect, or the third aspect and the various possible schemes in the third aspect, or the fourth aspect and the various possible schemes in the fourth aspect, and no repetition will be given here.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an application scenario;

FIG2 is a schematic diagram of another application scenario;

FIG3 is a flow chart of a communication method provided by the present application;

FIG4 is a flow chart of another communication method provided by the present application;

FIG5 is a flow chart of another communication method provided by the present application;

FIG6 is a flow chart of another communication method provided by the present application;

FIG7 is a flow chart of another communication method provided by the present application;

FIG8 is a flow chart of another communication method provided by the present application;

FIG9 is a flow chart of another communication method provided by the present application;

FIG10 is a flow chart of another communication method provided by the present application;

FIG11 is a schematic diagram of the structure of a communication device provided by the present application;

FIG12 is a structural diagram of a communication device provided in the present application.

DETAILED DESCRIPTION

The present application will be described in further detail below in conjunction with the accompanying drawings.

The embodiment of the present application provides a communication method and device to ensure that the terminal device maintains service continuity when moving between the coverage areas of the home operator network and the visited operator network with different network standards. The method and device described in the present application are based on the same technical concept. Since the principles of solving the problem by the method and the device are similar, the implementation of the device and the method can refer to each other, and the repeated parts will not be repeated.

Below, some terms involved in the embodiments of the present application are explained to facilitate understanding by those skilled in the art.

1) Access network equipment, equipment used to provide access for terminal equipment. Access network equipment may include radio access network (RAN) equipment, such as base stations. Access network equipment may be a base station, an evolved Node B in a long term evolution (LTE) system or an advanced long term evolution (LTE-A), which may be referred to as eNB or e-NodeB for short), a transmission reception point (TRP), a next generation base station (next generation NodeB, gNB) in a fifth generation (5G) mobile communication system, a next generation base station in a sixth generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a wireless local area network (WiFi) system, etc. It may also be an access network device in an open access network (open RAN, ORAN) system, etc. Optionally, the access network device may also be a module or unit that completes part of the functions of the base station. For example, the access network device may be a centralized unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), etc. The CU here completes the functions of the radio resource control protocol and the packet data convergence protocol (PDCP) of the base station, and can also complete the function of the service data adaptation protocol (SDAP); the DU completes the functions of the radio link control layer and the medium access control (MAC) layer of the base station, and can also complete part of the physical layer or all of the physical layer. Among them, in different systems, the CU (or CU-CP The CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU, DU may also be called open (open, O)-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CUP-UP, and RU may also be called O-RU.

Exemplarily, the access network device may be a macro base station, a micro base station (also called a small station) or an indoor station, or a relay node or a donor node, etc. The access network device may also be a radio network controller (RNC), a node B (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., home evolved NodeB, or home Node B, HNB), a baseband unit (BBU) or a remote radio unit (RRU), or a wireless fidelity (Wifi) access point (AP), or a baseband pool (BBU pool) and RRU in a cloud radio access network (CRAN), etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the access network device.

In the present application, the access network device may also be a functional module, a chip or a chip system. Optionally, the functional module, the chip or the chip system may be arranged in the access network device.

In this application, the shared access network device is an access network device that can be shared between different operators, and the shared access network device can be a 5G access network device.

2) Terminal equipment, also known as user equipment (UE), mobile station (MS), mobile terminal (MT), etc., is a device that provides voice and/or data connectivity to users. For example, terminal equipment may include handheld devices with wireless connection functions, vehicle-mounted devices, etc. At present, terminal devices can be: mobile phones, tablet computers, laptops, PDAs, mobile internet devices (MID), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, XR devices, MR devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, or wireless terminals in smart homes, etc.

The terminal device may also be a device-to-device (D2D) communication terminal device, a vehicle to everything (V2X) communication terminal device, an intelligent vehicle, a telematics box (TBOX), a machine-to-machine/machine-type communications (M2M/MTC) terminal device, or an Internet of Things (IoT) terminal device. For example, the terminal device may be a vehicle, ship, or aircraft, or a terminal-type roadside unit, or a communication module or chip built into a vehicle or roadside unit. For example, the terminal device may be a vehicle-mounted module. The terminal device may also be a roadside unit (RSU).

In the present application, the terminal device may also be a functional module, a chip or a chip system. Optionally, the functional module, the chip or the chip system may be arranged in the terminal device.

3) Public land mobile network (PLMN)

PLMN can be a network established and operated by the government or operators to provide land mobile communication services to the public. The network can be interconnected with the public switched telephone network (PSTN) to form a communication network on a regional or national scale. PLMN is used to distinguish different mobile communication operators in a country or region. A service area can be composed of one or several PLMNs. PLMN consists of a 3-digit mobile country code (MCC) and a 2-digit mobile network code (MNC).

PLMN is an important part of the international mobile subscriber identity (IMSI). IMSI is no more than 15 digits, the first 5 digits are PLMN, and the remaining digits are allocated by the network operator according to needs. IMSI is stored in the user's subscriber identity module (SIM) card or universal subscriber identity module (USIM). The PLMN in the IMSI is called the home public land mobile network (HPLMN). The HPLMN is the PLMN where the user opens an account. User information and the services available to the user are stored in the HPLMN. When a user leaves the coverage of the HPLMN and registers with another PLMN, the user enters the roaming state. The corresponding PLMN of the user when roaming is called the VPLMN.

A cell corresponds to one or more PLMNs, and the system information broadcast by the cell may include the identity information of the PLMN corresponding to the cell. The PLMNs corresponding to different cells may be the same or different.

When a terminal device accesses a network, it first searches for a PLMN, and after determining the PLMN, it performs a cell selection process on the PLMN and selects a suitable cell on the PLMN to reside in.

4) In the description of this application, the words "first", "second" and so on are only used for the purpose of distinguishing descriptions and should not be understood as indicating or implying The items are not intended to indicate relative importance, nor should they be understood as indicating or implying an order.

In the description of this application, "at least one" means one or more, and more means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, a and b, a and c, b and c, or a, b and c, where a, b, c can be single or plural.

In the description of this application, "and/or" describes the association relationship of the associated objects, indicating that there may be three relationships. For example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. "/" means "or", for example, a/b means a or b.

In order to more clearly describe the technical solution of the embodiments of the present application, the communication method and device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

FIG1 shows a schematic diagram of an application scenario. The application scenario shown in FIG1 can also be regarded as a schematic diagram of a roaming architecture, for example, a schematic diagram of a roaming architecture based on home routing (home routed, HR). The application scenario includes a visited public land mobile network (VPLMN/vPLMN) of a terminal device and a home public land mobile network (HPLMN/hPLMN) of the terminal device. The visited public land mobile network can also be referred to as a visited (or visited) public land mobile network or a visited network, and the home public land mobile network can also be referred to as a home public land mobile network or a home network.

vPLMN and hPLMN can communicate through their respective security edge protection proxies (SEPP). The SEPP in the vPLMN can be called a visited SEPP (vSEPP or VSEPP), and the SEPP in the hPLMN can be called a home SEPP (hSEPP or HSEPP). As shown in Figure 1, the vPLMN and hPLMN can communicate through the vSEPP and hSEPP.

Exemplarily, the vPLMN may also include a network slice selection function (NSSF) network element, a network exposure function (NEF) network element, a network repository function (NRF) network element, a policy control function (PCF) network element, a network slice admission control function (NSACF) network element, an access and mobility management function (AMF) network element, a session management function (SMF) network element and a user plane function (UPF) network element, etc.

In vPLMN, UE accesses the network through (R)AN, and UE can communicate with AMF through N1 interface (N1 for short); (R)AN communicates with AMF through N2 interface (N2 for short); (R)AN communicates with UPF in vPLMN through N3 interface (N3 for short); SMF in vPLMN communicates with UPF in vPLMN through N4 interface (N4 for short); UPFs in vPLMN can communicate with each other through N9 interface (N9 for short).

In addition, the NSSF, NEF, NRF, PCF, NSACF, AMF and SMF of the vPLMN can interact with each other using service-oriented interfaces. For example, the service-oriented interface provided by NSSF is Nnssf; the service-oriented interface provided by NEF is Nnef; the service-oriented interface provided by NRF is Nnrf; the service-oriented interface provided by PCF is Npcf; the service-oriented interface provided by NSACF is Nnsacf; the service-oriented interface provided by AMF is Namf; and the service-oriented interface provided by SMF is Nsmf.

Exemplarily, hPLMN may also include unified data management function (UDM) network element, NRF, NEF, NSSF, NSACF, SMF, AMF, authentication service function (AUSF) network element, PCF, application function (AF) network element and network slice-specific authentication and authorization function (NSSAAF) network element, etc.

In hPLMN, the SMF in hPLMN communicates with the UPF in hPLMN through N4; UPFs in hPLMN can communicate with each other through N9; UPF in hPLMN can also communicate with UPF in vPLMN through N9; UPF in hPLMN can also access the data network (DN) through N6 interface (N6 for short).

In addition, the UDM, NRF, NEF, NSSF, NSACF, SMF, AMF, AUSF, PCF, AF and NSSAAF of hPLMN can interact with each other using service-oriented interfaces. For example, the service-oriented interface provided by UDM is Nudm; the service-oriented interface provided by NRF is Nnrf; the service-oriented interface provided by NEF is Nnef; the service-oriented interface provided by NSSF is Nnssf; the service-oriented interface provided by NSACF is Nnsacf; the service-oriented interface provided by SMF is Nsmf; the service-oriented interface provided by SMF is Nsmf; the service-oriented interface provided by AMF is Namf; the service-oriented interface provided by AUSF is Nausf; the service-oriented interface provided by PCF is Npcf; the service-oriented interface provided by AF is Naf; and the service-oriented interface provided by NSSAAF is Nnssaaf.

The functions of some network elements involved in Figure 1 are described below:

AMF is responsible for access and mobility management functions, including user registration, reachability, mobility management, N1/N2 interface signaling transmission, access authentication and authorization, etc. For example, the AMF in the vPLMN can be responsible for the access and mobility management functions in the vPLMN, and the AMF in the hPLMN can be responsible for the access and mobility management functions in the vPLMN. The AMF in the hPLMN is responsible for access and mobility management functions in the hPLMN.

SMF is used to implement session management, including providing session management for UE sessions (such as session establishment, modification, and release), execution of control policies issued by PCF, selection and control of UPF, and allocation of Internet protocol (IP) addresses for UE. For example, the SMF in vPLMN is responsible for session management in vPLMN, and the SMF in hPLMN is responsible for session management in hPLMN.

UPF is responsible for the user plane functions of the core network, including forwarding and processing of user messages, connection with DN, session anchor, quality of service (QoS) policy execution, etc. For example, UPF in vPLMN is responsible for the user plane functions of the core network in vPLMN, and SMF in hPLMN is responsible for the user plane functions of the core network in hPLMN.

NRF is responsible for the registration, storage and management of network functions. For example, NRF in vPLMN is responsible for the registration, storage and management of network functions in vPLMN, and NRF in hPLMN is responsible for the registration, storage and management of network functions in hPLMN.

SEPP is responsible for the centralized and secure forwarding of signaling between the network and other networks, such as providing filtering and policies for control plane interface signaling when interacting across PLMNs, and hiding of network element topology within the PLMN. For example, vSEPP is responsible for the centralized and secure forwarding of signaling between vPLMN and other networks (such as hPLMN), and hSEPP is responsible for the centralized and secure forwarding of signaling between hPLMN and other networks (such as vPLMN).

The NSSF is responsible for determining the network slice used to provide services for the UE. For example, the NSSF in the vPLMN determines the network slice used to provide services for the UE accessing the vPLMN, and the NSSF in the hPLMN determines the network slice used to provide services for the UE accessing the hPLMN.

NEF is responsible for providing the function of opening network data to the outside world. For example, NEF in vPLMN provides the function of developing network data for VPLMN, and NEF in hPLMN provides the function of developing network data for hPLMN.

The PCF is responsible for policy control functions, including charging for sessions and service flows, QoS bandwidth guarantee, mobility policy management, terminal device access policy, etc. For example, the PCF in the hPLMN is responsible for policy control functions in the hPLMN.

NSACF is responsible for controlling the number of terminal devices registered for each network slice and the number of sessions corresponding to each network slice. For example, NSACF in vPLMN can be used to control the number of terminal devices registered for network switching in vPLMN and the number of sessions corresponding to each network slice.

UDM is responsible for unified data management functions, including user contract management, access authorization, authentication information generation, etc. For example, UDM in hPLMN is responsible for unified data management functions in hPLMN.

AUSF is responsible for the authentication service function. For example, AUSF in hPLMN is responsible for the authentication service function in hPLMN.

The AF is responsible for providing application layer services. For example, the AF in the hPLMN is responsible for providing application layer services in the hPLMN.

NSSAAF is responsible for the authentication and authorization of network slices. For example, NSSAAF in hPLMN is responsible for the authentication and authorization of network slices in hPLMN.

FIG2 shows a schematic diagram of another application scenario. The application scenario shown in FIG2 can also be regarded as a roaming structural schematic diagram, for example, a HR roaming architecture schematic diagram of the interoperability scenario between the 5G system (5G system, 5GS) and the 4G evolved packet core (evolved packet core, EPC) or the evolved universal mobile telecommunications system (universal mobile telecommunications system, UMTS) terrestrial radio access network (evolved UMTS terrestrial radio access network, E-UTRAN). The application scenario includes the vPLMN of the terminal device and the hPLMN of the terminal device.

Exemplarily, the vPLMN may include a 4G EPC and a 5G system. Among them, the 4G EPC may include E-UTRAN, a mobility management entity (MME), a service gateway (SGW), etc. The UE may access the 4G EPC through the 4G access network E-UTRAN, such as accessing the MME so that the MME can manage the UE. The 5G system may include the next generation RAN (NG-RAN), AMF, UPF, v-SMF, v-PCF, etc. The UE may access the 5G core network through the NG-RAN, for example, the UE may access the 5G core network element AMF, so that the AMF can manage the UE.

In the 4G EPC of vPLMN, E-UTRAN can communicate with MME through the S1-MME interface; E-UTRAN can communicate with SGW through the S1-U interface; MME can communicate with SGW through the S11 interface. In the 5G system of vPLMN, UE can communicate with AMF through the N1 interface; NG-RAN can communicate with AMF through the N2 interface; NG-RAN can communicate with UPF through the N3 interface; UPF can communicate with v-SMF through the N4 interface; AMF can communicate with v-SMF through the N11 interface; AMF can communicate with v-PCF through the N15 interface. The 4G EPC of vPLMN and the 5G system can communicate through the N26 interface between MME and AMF.

Exemplarily, the hPLMN may include a network element integrating UPF and public data network (PDN) gateway (PDNateway, PGW) user plane (PGW-U) functions (as shown in UPF+PGW-U in FIG. 2, where "+" indicates that UPF and PGW-U can be co-located), a network element integrating SMF and PGW control plane (PGW-C) functions (as shown in SMF+PGW-C in FIG. 2, where "+" indicates that SMF and PGW-C can be co-located), h-PCF, and a network element integrating home subscriber server (home subscriber server, HSS) and UDM functions (as shown in HSS+UDM in FIG. 2, where "+" indicates that HSS and UDM can be co-located). Assume) etc.

In hPLMN, UPF+PGW-U can communicate with SMF+PGW-C through the N4 interface; SMF+PGW-C can communicate with h-PCF through the N7 interface; SMF+PGW-C can communicate with HSS+UDM through the N10 interface.

In addition, the UPF+PGW-U in the hPLMN can communicate with the SGW in the 4G EPC of the vPLMN through the S8-U interface. The SMF+PGW-C in the hPLMN can communicate with the SGW in the 4G EPC of the vPLMN through the S8-C interface. The HSS+UDM in the hPLMN can communicate with the MME in the 4G EPC of the vPLMN through the S6a interface. The UPF+PGW-U in the hPLMN can communicate with the UPF in the 5G system of the vPLMN through the N9 interface. The SMF+PGW-C in the hPLMN can communicate with the v-SMF in the 5G system of the vPLMN through the N16 interface. The h-PCF in the hPLMN can communicate with the v-PCF in the 5G system of the vPLMN through the N24 interface. The HSS+UDM in the hPLMN can communicate with the AMF in the 5G system of the vPLMN through the N8 interface.

The functions of some network elements involved in Figure 2 are described below:

MME is responsible for the mobility management of users in the evolved packet system (EPS).

The SGW is responsible for the forwarding and routing of mobile anchor points and service packets in the EPS system.

PGW is responsible for packet detection, transmission message marking and IP address allocation, QOS strategy and charging strategy in the EPS system.

SMF+PGW-C is mainly used to establish sessions in the interoperation between 4G and 5G networks.

UPF+PGW-U is mainly used for forwarding user plane messages in the interoperability between 4G and 5G networks.

It should be understood that the application scenarios shown in FIG. 1 and FIG. 2 are not limited to including only the network elements shown in the figures, but may also include other devices not shown in the figures, which are not listed one by one here.

In addition, the distribution forms shown in FIG. 1 and FIG. 2 are merely exemplary and not limiting.

For the convenience of explanation, this application will refer to XX network element as XX, for example, SMF network element as SMF. It should be understood that the names of all network elements in this application are only examples, and they may be called other names in future communications, or the network elements involved in this application may be replaced by other entities or devices with the same functions in future communications, and this application does not limit this. A unified explanation is given here, and no further description will be given later.

The current roaming scenario only supports the terminal device to maintain service continuity when moving between coverage areas of different network standards in the visited operator network (4G coverage area and 5G coverage area), and does not support the terminal device to maintain service continuity when moving between coverage areas of different network standards of the home operator network and the visited operator network. For example, when the terminal device accesses the visited operator network, when the terminal device moves from the 5G coverage area of the visited operator network to the 4G coverage area of the home operator network, the terminal device will disconnect from the visited operator network during the movement and re-initiate a registration request to the home operator network, which will cause service interruption of the terminal device. Based on this, an embodiment of the present application provides a communication method and device to ensure that the terminal device maintains service continuity when moving between coverage areas of different network standards of the home operator network and the visited operator network. In addition, the communication method and device provided in the present application can be applied to the application scenarios shown in Figure 1 or Figure 2 above without limitation.

The present application provides a communication method. Referring to FIG. 3 , the process of the method may include the following steps:

Step 301: A first mobility management network element receives a first switching request message from a first access network device, where the first switching request message is used to request switching of a terminal device from a first-standard network in a first operator network to a second-standard network in a second operator network.

The first operator network may be a visited operator network of the terminal device, and the second operator network may be a home operator network of the terminal device.

The first standard network may be a 5G network, and the second standard network may be a 4G network. It should be understood that in future communications, the first standard network may also be a 6G network, and the second standard network may also be a 5G network, and this application does not limit this. In the description of this application, only the first standard network is a 5G network, and the second standard network is a 4G network as an example for illustration, which is not a limitation of this application.

The first mobility management network element belongs to a first-standard network in a first operator network. For example, the first mobility management network element may be a vAMF.

It should be pointed out that network sharing is a way for operators to share mobile network resources. Network sharing enables operators to maximize network deployment and improve overall network quality. The 3rd Generation Partnership Project (3GPP) system can support different types of network sharing since the standard Rel-5. For example, different operators can connect to a shared wireless access network, which is also called access network sharing. Currently, the shared access network is usually a 5G access network.

The first access network device is a shared access network device, and the terminal device can access the first standard network in the first operator network through the first access network device. In other words, the first access network device is an access network device in the shared access network of the first operator network and the second operator network.

Step 302: The first mobility management network element determines, based on the first switching request message, that the terminal device is allowed to switch from a first-standard network in the first operator's network to a second-standard network in the second operator's network.

In an optional implementation, the first switching request message may include an identifier of the first PLMN currently used by the terminal device. Accordingly, the first mobile management network element determines, based on the first switching request message, that the terminal device is allowed to switch from the first standard network in the first operator network to the second standard network in the second operator network. The method may be: the first mobile management network element determines that the identifier of the first PLMN is a shared PLMN identifier of the second operator network, and the shared PLMN identifier is used for users of the second operator network to access the shared access network device of the first operator network.

The identifier of the first PLMN currently used by the terminal device can also be understood as the identifier of the PLMN currently selected by the terminal device for access, or can also be understood as the identifier of the PLMN used by the terminal device to access the shared access network device. The identifier of the first PLMN can be described as the identifier of the selected PLMN (selected PLMN ID).

In a possible manner, the first PLMN (ie, the shared PLMN) may be different from the PLMN (eg, recorded as a third PLMN) used by subscribers of the first operator network to access the first operator network.

In another possible manner, the first PLMN may also be the same as the PLMN (for example, recorded as a third PLMN) used by subscribers of the first operator network to access the first operator network.

Exemplarily, the first switching request message may also include an identifier of a target access network device of the terminal device (e.g., target eNB ID). Further, the first mobility management network element may determine an identifier of a second PLMN to which the target access network device belongs based on the identifier of the target access network device, and the second PLMN corresponds to the second operator network.

Optionally, the identifier of the target access network device may include a mobile country code (MCC), a mobile network code (MNC), and a base station identifier (e.g., eNB ID). Since the PLMN ID may be composed of an MCC and an MNC, the first mobile management network element may determine the identifier of the second PLMN based on the MCC and MNC in the identifier of the target access network device.

Furthermore, the first mobile management network element can determine that the identifier of the first PLMN is the shared PLMN identifier of the second operator network by the following method: the first mobile management network element determines that the first PLMN and the second PLMN are equivalent PLMNs (equal PLMN) based on the identifier of the first PLMN and the identifier of the second PLMN.

The first mobility management network element determines that there is an equivalent mapping relationship between the identifier of the first PLMN and the identifier of the second PLMN, and then the first mobility management network element determines that the first PLMN and the second PLMN are equivalent PLMNs. Exemplarily, the first mobility management network element locally stores the equivalent mapping relationship between the identifier of the first PLMN and the identifier of the second PLMN.

Step 303: The first mobility management network element sends a second handover request message to the second mobility management network element, where the second handover request message is used to request handover of the terminal device from the first standard network in the first operator network to the second standard network in the second operator network. Correspondingly, the second mobility management network element receives the second handover request message from the first mobility management network element.

The second mobility management network element belongs to the first-standard network in the second operator network.

The second mobility management network element may be hAMF.

In some embodiments, when the first switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from a first-standard network to a second-standard network, the first mobility management network element sends a second switching request message to the second mobility management network element.

For example, the first switching reason value may be an inter-system handover indication (inter system handover indication), and the inter-system handover indication is used to instruct the terminal device to switch from a 5G network to a 4G network.

In an optional implementation manner, the first mobility management network element may select the second mobility management function network element by the following method, and then send the second handover request message to the second mobility management network element:

Method a1: The first mobility management network element determines the second mobility management network element according to the corresponding relationship between the first PLMN currently used by the terminal device configured locally and the second mobility management network element.

For example, the first mobile management network element is locally configured with a correspondence between the first PLMN and one or more mobile management network elements belonging to the second operator network. The first mobile management network element can determine the second mobile management network element from the one or more mobile management network elements belonging to the second operator network based on the first PLMN.

Method a2: The first mobility management network element obtains the identifier of the second mobility management network element from the network storage network element according to the identifier of the first PLMN, wherein the network storage network element stores the correspondence between the first PLMN and the second mobility management network element. For example, the network storage network element stores the correspondence between the identifier of the first PLMN and the identifier of the second mobility management network element.

Before the first mobility management network element sends the second handover request message to the second mobility management network element, the first mobility management network element may generate the second handover request message according to the first handover request message.

The second switching request message may include the identifier of the second PLMN and the information in the first switching request message except the identifier of the first PLMN.

For example, the first mobility management function network element replaces the identifier of the first PLMN in the first switching request message with the identifier of the second PLMN to obtain the second switching request message.

In an example, the second switching request message may include an identifier of the second PLMN, an identifier of the target access network device, and a first switching reason value.

In an optional implementation, the second handover request message may further include first indication information, where the first indication information is used to instruct the second mobility management network element to forward the received handover completion notification message to the first mobility management network element.

Optionally, the first indication information is used by the second mobile management network element to determine that before receiving the second switching request message, the terminal device sends a message through the shared access network device to request to switch the terminal device from the first-standard network in the first operator network to the second-standard network in the second operator network.

Step 304: The second mobility management network element sends a third handover request message to the third mobility management network element according to the second handover request message.

The third switching request message may be used to request switching of the terminal device from a first-standard network in the first operator network to a second-standard network in the second operator network.

The third mobility management network element belongs to the second-standard network in the second operator's network.

For example, the third mobility management network element may be hMME.

Exemplarily, when the second switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from a first-standard network to a second-standard network, the second mobility management network element sends a third switching request message to the third mobility management network element.

Furthermore, after receiving the third switching request message sent by the second mobile management network element, the third mobile management network element can interact with other network elements in the second operator network (such as SGW, SMF+PGW-C, UPF+PGW-U, hPCF and other network elements) to complete the establishment of the public data network (public data network, PDN) connection of the second operator network.

Further optionally, the third mobility management network element sends a first handover response message to the second mobility management network element, and the first handover response message can be used to respond to the third handover request message.

Exemplarily, the first switching response message may include one or more of the following information: cause, target to source transparent container, EPS bearer setup list, addresses and tunnel endpoint identifiers (TEIDs).

The reason may be a reason received by the third mobility management network element from the access network device side (i.e., the target access network device) of the second operator's network, and the reason may be used to indicate access success or access failure. For example, the reason may indicate that the access network device has completed wireless resource preparation, or agrees to switch the terminal device from the source side to the target side, or the reason may indicate that wireless resource preparation is not completed, or the switching of the terminal device is not agreed.

The target-side to-source-side transparent container may include some characteristics supported by the target-side access network device, such as a characteristic used by the source side to retrieve the corresponding characteristic on the target side.

The EPS bearer setup list refers to the EPS bearer list established by the second operator network side according to the protocol data unit (PDU) session information. The PDU session information may specifically be the information carried in the aforementioned handover request message.

The addresses and TEIDs may include SGW addresses used to establish an indirect data forwarding path and TEIDs of the user plane data tunnel established on the second-standard network side of the second operator for data forwarding.

Further optionally, the second mobility management network element sends a second handover response message to the first mobility management network element, and the second handover response message may be used to respond to the second handover request message. The second handover response message may include the information in the aforementioned first handover response message.

Further optionally, the second mobility management network element establishes a connection data forwarding tunnel according to information in the second switching response message, and sends a third switching response message to the first access network device, where the third switching response message is used to respond to the first switching request message.

Furthermore, the first access network device sends a switching command to the terminal device to trigger the terminal device to initiate a switch to the target access network device, so that the terminal device is reconfigured to the target access network device.

Optionally, when the third switching response message includes information about the indirect data forwarding path, the first access network device forwards the received data to the target access network device through the indirect forwarding path.

After the terminal device switches to the target access network device, the terminal device may send a switching completion notification message to the third mobility management network element, where the switching completion notification message is used to notify the terminal device that it has switched to the second-standard network in the second operator's network.

The third mobility management network element sends the switching completion notification message to the second mobility management network element. Further, the second mobility management network element sends the switching completion notification message to the first mobility management network element according to the first indication information included in the second switching request message.

Optionally, the handover completion notification message may carry a relocation complete notification indication, which may be used to indicate that the terminal device has successfully switched to the second standard network in the second operator network. The indication notifies the session management network element to release the PDU session in the first operator network.

In one example, the first mobility management network element may send a request to release the PDU session to the session management network element. After receiving the message of the completion of the PDU session release from the session management network element, the first mobility management network element may send a switching completion confirmation message to the second mobility management network element, and the switching completion confirmation message indicates that the session of the terminal device in the first operator network has been released.

The switching completion confirmation message may carry a relocation complete ack indication, which indicates that the switching process has been completed on the first operator network side.

Further, the second mobility management network element sends the switching completion confirmation message to the third mobility management network element.

Through the above communication method, the switching request between different standards initiated by the terminal device in the visited operator network can be converted into two steps: switching between the same standard between the home operator network and the visited operator network and switching between different standards of the home operator network. Subsequently, it can be ensured that the terminal device maintains service continuity when moving between the coverage areas of different network standards of the home operator network and the visited operator network.

Based on the embodiment shown in Figure 3, Figure 4 shows an example of a communication method, in which the first operator network is the visited operator network of the terminal device, the second operator network is the home operator network of the terminal device, the first standard network is a 5G network, the second standard network is a 4G network, the first access network device is a shared RAN, the first mobile management network element is vAMF, the second mobile management network element is hAMF, and the third mobile management network element is hMME. In this example, when the UE switches from the shared 5G network to the 4G network in the home operator network, the vAMF determines whether the UE is allowed to initiate a switch to the 4G network in the home operator network, and forwards the switching request to the hAMF in the home operator network, and the hAMF selects a suitable hMME and forwards data. That is, this example authenticates the switching request based on the vAMF, and the hAMF reconfigures the UE context. Exemplarily, the process of this example may include the following steps:

Step 401: The shared RAN sends a first handover request message to the vAMF.

Among them, the first switching request message is used to request to switch the UE from the 5G network of the visited operator network to the 4G network of the home operator network.

The first handover request message may include a target eNB ID and a first handover reason value (e.g., inter system handover indication). Specifically, the target eNB ID and the first handover reason value may refer to the aforementioned description and will not be described in detail here.

The first handover request message may also include an identifier of a first PLMN currently used by the UE. The identifier of the first PLMN can refer to the above description and will not be described in detail here.

Step 402: The vAMF determines, based on the first switching request message, that the UE is allowed to switch from the 5G network of the visited operator network to the 4G network of the home operator network.

Specifically, vAMF determines the method for allowing the UE to switch from the 5G network of the visited operator network to the 4G network of the home operator network based on the first switching request message. Please refer to the method for the aforementioned first mobile management network element to determine the method for allowing the terminal device to switch from the first-standard network in the first operator network to the second-standard network in the second operator network based on the first switching request message. It will not be repeated here.

Step 403: vAMF sends a second switching request message to hAMF.

The second switching request message is used to request to switch the UE from the 5G network of the visited operator network to the 4G network of the home operator network.

The second handover request message may include the target eNB ID, the first handover reason value (inter system handover indication), the identifier of the second PLMN and the first indication information.

The description of the first indication information can refer to the above description and will not be repeated here.

Step 404: hAMF sends a third handover message to hMME according to the second handover request message.

Among them, the third switching request message is used to request to switch the UE from the 5G network of the visited operator network to the 4G network of the home operator network.

Exemplarily, when the second switching request message includes the first switching reason value, and the first switching reason value is used to indicate that the UE switches from the 5G network to the 4G network, the hAMF sends a third switching request message to the hMME element.

Optionally, the hAMF may select a hMME with the first indication information based on the target eNB ID in the second switching request message.

Step 405: hMME completes the home operator network handover preparation.

For example, hMME interacts with other network elements in the home operator network (such as SGW, SMF+PGW-C, UPF+PGW-U, HPCF, etc.) to complete the establishment of PDN connection on the home operator network side.

Step 406: hMME sends a first handover response message to hAMF, where the first handover response message is used to respond to the third handover request message.

The first switching response message may include one or more of the following information: cause, target to source transparent transmission container, source transparent container), EPS bearer setup list (EPS bearer setup list), addresses and tunnel endpoint identifiers (addresses and tunnel endpoint identifiers (TEIDs)). For details, please refer to the above related description, which will not be repeated here.

Step 407: hAMF sends a second handover response message to vAMF.

The second switching response message is used to respond to the second switching request message.

The second handover response message may include the information in the first handover response message.

Step 408: The vAMF establishes a connection data forwarding tunnel according to the information in the second handover response message, and sends a third handover response message to the shared RAN.

The third switching response message is used to respond to the first switching request message.

Step 409: The shared RAN sends a handover command to the UE.

The handover command may instruct the UE to handover to the target eNB.

Optionally, if the third handover response message includes information about the indirect data forwarding path, the shared RAN forwards the received downlink data to the target eNB through the indirect data forwarding path.

Step 410: After the UE switches to the target eNB in the home operator's network, it sends a switching completion notification message to the hMME.

The switching completion notification message is used to notify the UE that it has switched to the 4G network in the home operator's network.

Step 411: hMME sends a handover completion notification message to hAMF.

Step 412: hAMF forwards the handover completion notification message received from hMME to vAMF according to the first indication information included in the second handover request message.

Optionally, the handover completion notification message carries a relocation complete notification indication, which can be used to indicate that the UE has successfully switched to the 4G network in the home operator network. Based on this indication, the vAMF can notify the vSMF to release the PDU session in the visited operator network.

Step 413: vAMF sends a request to release the PDU session to vSMF, and after receiving the PDU session release completion message from vSMF, sends a switching completion confirmation message to hAMF.

The handover completion confirmation message may indicate that the session of the UE in the visited operator network has been released.

Among them, the switching completion confirmation message can carry a redirection completion confirmation indication (relocation complete ack indication), which indicates that the switching process has been completed on the visited operator network side.

Step 414: hAMF sends a handover completion confirmation message to hMME.

In the above method, vAMF forwards the handover request message received when the UE switches from the shared 5G network to the 4G network of the home operator to hAMF, and hAMF assists in the interaction of handover signaling between the 5G network and the 4G network when the UE switches from the shared 5G network to the 4G network of the home operator. In the scenario where the shared 5G network and the 4G network of the home operator cannot communicate directly, the UE is guaranteed to maintain service continuity when moving from the 5G network of the visited operator network to the 4G network of the home operator network.

In addition to the above-mentioned communication method, the embodiment of the present application also provides the communication method shown in Figures 5 and 6, which can ensure that the UE maintains service continuity when moving from the 5G network of the visited operator network to the 4G network of the home operator network.

In the example shown in FIG5 , when the UE switches from the shared 5G network to the 4G network in the home operator network, the vAMF determines that the vAMF supports this type of switching based on the type of switching request, and forwards this type of switching to the corresponding hAMF with a proxy function, and the hAMF forwards the switching-related messages between the vAMF and the hMME, so as to achieve service continuity during the UE switching from the shared 5G network to the home operator 4G network. Exemplarily, the process of this example may include the following steps:

Step 501: Sharing the handover request message 1 sent by the RAN to the vAMF.

Among them, the switching request message 1 is used to request to switch the UE from the 5G network of the visited operator network to the 4G network of the home operator network.

The information carried in the handover request message 1 may include a target eNB ID and a first handover reason value (e.g., inter system handover indication). Specifically, the target eNB ID and the first handover reason value may refer to the aforementioned description and will not be described in detail here.

The handover request message 1 may also include an identifier of the first PLMN currently used by the UE. The identifier of the first PLMN can refer to the above description and will not be described again here.

Optionally, the handover request message 1 may also include a source to target transparent container. The source to target transparent container may include information about the source side shared RAN, such as: data flow (QoS flow) or radio bearer information that needs to be forwarded. The source to target transparent container will be transparently transmitted to the target RAN side, and is used by the target RAN to allocate or configure the target side radio bearer resources according to the information on the source side.

Step 502: The vAMF determines, based on the handover request message 1, that the UE is allowed to switch from the 5G network of the visited operator network to the 5G network of the home operator network. The 4G network of the commercial network.

Specifically, the method in which vAMF determines, based on the switching request message 1, that the UE is allowed to switch from the 5G network of the visited operator network to the 4G network of the home operator network is similar to the method in which the aforementioned first mobile management network element determines, based on the first switching request message, that the terminal device is allowed to switch from the first-standard network in the first operator network to the second-standard network in the second operator network. They can refer to each other and are not described in detail here.

Step 503: vAMF generates a switching request message 2 (such as a redirection request relocation request) based on the switching request message 1, encapsulates the switching request message 2 in an N14 container, and sends the N14 message 1 to the hAMF.

The N14 message 1 includes the N14 container.

Among them, the switching request message 2 may include the target eNB ID, the identifier of the second PLMN and the first switching reason value.

Optionally, the handover request message 2 may also include source to target transparent container and/or MME UE context.

Exemplarily, the N14 message 1 may also include a target ID and indication information 1 (such as a forward indication (forward_indication)).

Among them, indication information 1 can indicate the specific action of hAMF after receiving the N14 message. For example, indication information 1 can instruct hAMF to select hMME according to target ID and forward the data in N14 container to the selected hMME.

Optionally, the indication information 1 may also indicate that when hAMF receives the message sent by hMME, it encapsulates it into the N14 container and forwards it to vAMF.

Step 504: After hAMF receives the N14 message sent by vAMF, it selects hMME according to the N14 message and forwards the switching request message 2 in the N14 container to hMME.

Exemplarily, hAMF may select hMME based on the target eNB ID and forward_indication in N14 message 1.

Step 505: hMME completes the home operator network handover preparation.

For example, hMME interacts with other network elements in the home operator network (such as SGW, SMF+PGW-C, UPF+PGW-U, HPCF, etc.) to complete the establishment of PDN connection on the home operator network side.

Step 506: hMME sends a handover response message 1 to hAMF. The handover response message 1 is used to respond to the handover request message 2 sent by hAMF.

Step 507: hAMF encapsulates the handover response message 1 received from hMME into an N14 container, and sends an N14 message 2 to vAMF.

The N14 message 2 includes the N14 container.

Optionally, hAMF encapsulates the switching response message 1 received from hMME into an N14 container according to the indication information 1 in the N14 message 1, and sends an N14 message 2 to vAMF.

Step 508: The vAMF parses the N14 message 2, obtains the switching response message 1, establishes an indirect data forwarding tunnel according to the switching response message 1, and sends the switching response message 2 to the shared RAN.

The switching response message 2 is used to respond to the switching request message 1.

Step 509: The shared RAN sends a handover command to the UE.

The handover command may instruct the UE to handover to the target eNB.

Optionally, if the handover response message 2 includes information about the indirect data forwarding path, the shared RAN forwards the received downlink data to the target eNB through the indirect data forwarding path.

Step 510: After the UE switches to the target eNB in the home operator's network, it sends a switching completion notification message to the hMME.

The switching completion notification message is used to notify the UE that it has switched to the 4G network in the home operator's network.

Step 511: hMME sends a handover completion notification message to hAMF.

Step 512: hAMF encapsulates the received handover completion notification message of hMME in an N14 container according to indication information 1 in N14 message 1, and sends N14 message 3 to vAMF, where N14 message 3 includes the N14 container.

Step 513: After vAMF parses N14 message 3 to obtain the handover completion notification message, it sends a request to release the PDU session to vSMF. After receiving the PDU session release completion message from vSMF, vAMF generates a handover completion confirmation message, encapsulates the handover completion confirmation message into an N14 container, and sends N14 message 4 to hAMF, which includes the N14 container.

The handover completion confirmation message may indicate that the session of the UE in the visited operator network has been released.

Among them, the switching completion confirmation message can carry a redirection completion confirmation indication (relocation complete ack indication), which indicates that the switching process has been completed on the visited operator network side.

Step 514: hAMF parses the N14 container in N14 message 4, and forwards the handover completion confirmation message in the N14 container to hMME.

Through the above method, vAMF converts the received switching request message 1 of the shared RAN into a switching request message 2 that needs to be sent to hMME and encapsulates it in the N14 container, and at the same time provides hAMF with an indication of selecting hMME. After receiving the message, hAMF directly forwards the message in the N14 container to hMME, and encapsulates the received reply message of hMME in the N14 container and forwards it to vAMF. hAMF only acts as an agent for transparent transmission of messages between vAMF and hMME. The above method ensures that the UE maintains service continuity when moving from the 5G network of the visited operator network to the 4G network of the home operator network in a scenario where direct communication is not possible between the shared 5G network and the home operator's 4G network.

In the example shown in Figure 6, a switching scheme is shown when the UE is accessed in the shared RAN and its mobility management context is saved in the hAMF and switched to the home operator's 4G network. This scheme uses vAMF as a proxy to transmit messages between the shared RAN and hAMF. Whether the UE is allowed to switch to the home 4G network is initially authenticated by the hAMF. After receiving the message sent by the shared RAN, the vAMF determines which network the UE belongs to based on the selected PLMN of the message, and forwards it directly to the hAMF in the locally configured PLMN that manages the UE. The hAMF determines whether the UE is allowed to make such a switch and interacts with the hMME to complete the UE's switch from the shared RAN to the home operator's 4G network. Exemplarily, the process of this example may include the following steps:

Step 601: Sharing the handover request message 1 sent by the RAN to the vAMF.

Among them, the switching request message 1 is used to request to switch the UE from the 5G network of the visited operator network to the 4G network of the home operator network.

The information carried in the handover request message 1 may include a target eNB ID and a first handover reason value (e.g., inter system handover indication). Specifically, the target eNB ID and the first handover reason value may refer to the aforementioned description and will not be described in detail here.

The handover request message 1 may also include an identifier of the first PLMN currently used by the UE (e.g., selected PLMN). The identifier of the first PLMN can be found in the above description and will not be repeated here.

Step 602: The vAMF encapsulates the switching request message 1 into the N14 container, and sends the N14 message 1 to the hAMF corresponding to the pre-configured first PLMN identifier.

The N14 message 1 includes the N14 container.

Exemplarily, the vAMF preconfigures the correspondence between the shared PLMN identifier and the AMF. For example, if the shared PLMN identifier is 46022, it corresponds to hAMF1; if the shared PLMN identifier is 46023, it corresponds to hAMF2.

Optionally, if the vAMF determines that the first PLMN identifier is a shared PLMN identifier of the home operator network, the N14 message 1 is sent to the hAMF corresponding to the pre-configured first PLMN identifier.

Among them, the method for vAMF to determine that the first PLMN identifier is a shared PLMN identifier of the home operator network can refer to the relevant method involved in the embodiment shown in Figure 3, and will not be described in detail here.

Step 603: hAMF parses N14 message 1, obtains the switching request message 1 in the N14 container, and determines, based on the switching request message 1, that the UE is allowed to switch from the 5G network of the visited operator network to the 4G network of the home operator network.

Among them, the method in which hAMF determines, based on the switching request message 1, that the UE is allowed to switch from the 5G network of the visited operator network to the 4G network of the home operator network, is similar to the method in which the first mobile management network element determines, based on the first switching request message, that the terminal device is allowed to switch from the first-standard network in the first operator network to the second-standard network in the second operator network in the embodiment shown in Figure 3. They can refer to each other and are not described in detail here.

Step 604: The vAMF generates a handover request message 2 according to the handover request message 1, and sends the handover request message 2 to the hMME.

Exemplarily, hAMF can find the corresponding hMME based on the target eNB ID.

Optionally, hAMF may request hSMF+PGW-C to obtain the UE EPS PDN connection information corresponding to the UE's PDU session, and generate a switching request message 2 based on the information in the switching request message 1 and the obtained UE EPS PDN connection information.

Step 605: hMME completes the home operator network handover preparation.

For example, hMME interacts with other network elements in the home operator network (such as SGW, SMF+PGW-C, UPF+PGW-U, HPCF, etc.) to complete the establishment of PDN connection on the home operator network side.

Step 606: hMME sends a handover response message 1 to hAMF.

Among them, the switching response message 1 is used to respond to the switching request message 2 sent by the hAMF.

Step 607: After receiving the handover response message 1, hAMF generates a handover command, which can instruct the UE to handover to the target eNB. hAMF encapsulates the handover command in an N14 container and sends a handover response message 2 to vAMF.

The switching response message 2 includes an N14 container.

Optionally, hAMF determines whether a data forwarding tunnel needs to be established based on the received switching response message 1. If necessary, hAMF triggers hSMF+PGW-C to communicate with the visited operator network side based on the information of the data forwarding tunnel in the received switching response message 1. A data forwarding tunnel is established between the two networks, and the information of the data forwarding tunnel of the visited operator network is included in the generated handover command together with other information in the handover response message 1.

If the switching response message 1 includes the information of the data forwarding tunnel, it means that the data forwarding tunnel needs to be established, otherwise it does not need to be established.

Step 608: The vAMF parses the handover response message 2 and forwards the handover command in the N14 container to the shared RAN.

Step 609: The shared RAN sends a handover command to the UE.

Optionally, if the handover command includes information of the indirect data forwarding path, the shared RAN forwards the received downlink data to the target eNB through the indirect data forwarding path.

Step 610: After the UE switches to the target eNB in the home operator's network, it sends a switching completion notification message to the hMME.

The switching completion notification message is used to notify the UE that it has switched to the 4G network in the home operator's network.

Step 611: hMME sends a handover completion notification message to hAMF.

Step 612: hAMF confirms that the handover has been completed according to the handover completion notification message and needs to release the session on the visited operator network side. hAMF releases the PDU session on the vSMF side through hSMF+PGW-C. Then, hAMF sends N14 message 2 to vAMF, and N14 message 2 contains N14 container, which contains the handover completion notification message.

Step 613: vAMF sends N14 message 3 to hAMF. N14 message 3 includes an N14 container, and the N14 container includes a switching completion confirmation message 1.

The handover completion confirmation message 1 may indicate that the session of the UE in the visited operator network has been released.

Step 614: hAMF generates a switching completion confirmation message 2 according to the result information of hSMF+PGW-C releasing the vSMF side session and the switching completion confirmation message 1 returned by VAMF, and sends the switching completion confirmation message 2 to hMME.

Through the above method, in the scenario where the shared 5G network and the home operator's 4G network cannot communicate directly, it is achieved to ensure that the UE maintains service continuity when moving from the 5G network of the visited operator's network to the 4G network of the home operator's network.

The above describes a method for ensuring that the service continuity is maintained when the terminal device moves from the first standard network of the visited operator network to the second standard network of the home operator network, such as a method for ensuring that the service continuity is maintained when the UE moves from the 5G network of the visited operator network to the 4G network of the home operator network. The following describes a method for ensuring that the service continuity is maintained when the UE moves from the second standard network of the home operator network to the first standard network of the visited operator network, such as a method for ensuring that the service continuity is maintained when the UE moves from the 4G network of the home operator network to the 5G network of the visited operator network.

FIG7 shows a communication method, which can ensure that the terminal device maintains service continuity when it moves from the second standard network of the home operator network to the first standard network of the visited operator network. Exemplarily, the process of the method may include the following steps:

Step 701: The second mobility management network element receives a first switching request message from a third mobility management network element, where the first switching request message is used to request switching of a terminal device from a second-standard network in a second operator network to a first-standard network in a first operator network.

The second mobility management network element belongs to a first-standard network in the second operator network; and the third mobility management network element belongs to a second-standard network in the second operator network.

For example, the second mobility management network element may be hAMF.

For example, the third mobility management network element may be hMME.

The first operator network may be a visited operator network of the terminal device, and the second operator network may be a home operator network of the terminal device.

The first-standard network may be a 5G network, and the second-standard network may be a 4G network.

In one embodiment, after the third mobility management network element receives a message from the source access network device requesting to switch the terminal device from the second-standard network in the second operator network to the first-standard network in the first operator network, it sends a first switching request message to the second mobility management network element.

The source access network device is the current access network device of the terminal device, and the source access network device is used for the terminal device to access the first-standard network of the second operator.

Step 702: The second mobility management network element determines, based on the first switching request message, that the target access network device of the terminal device is a shared access network device, and the target access network device is used for the terminal device to access the first operator's network.

In an optional embodiment, the first switching request message includes an identifier of the target access network device (e.g., target gNB ID).

Further, the second mobility management network element determines that the target access network device of the terminal device is a shared access network device according to the first switching request message, and the method may be: the second mobility management network element determines the identifier of the first PLMN to which the target access network device belongs according to the identifier of the target access network device, and the first PLMN corresponds to the first operator network; if the identifier of the first PLMN corresponds to the shared PLMN identifier, the second mobility management network element determines that the target access network device of the terminal device is a shared access network device; wherein the shared PLMN identifier is used for the first Users of the second operator network access the shared access network device of the first operator network.

Exemplarily, if the identifier of the first PLMN corresponds to the shared PLMN identifier, the second mobile management network element determines that the target access network device of the terminal device is a shared access network device. For example, it can be: the second mobile management network element confirms through querying HSS/UDM or local configuration that there is a sharing agreement between the first operator network corresponding to the identifier of the first PLMN and the second operator network, that is, the device of the second operator network can access the shared device of the first operator network through the shared PLMN allocated by the first operator network. Then the second mobile management network element determines that the target access network device of the terminal device is a shared access network device.

Among them, when the terminal device accesses the shared access network device, the shared PLMN identifier is used, that is, the shared PLMN identifier can be understood as the identifier of the PLMN used by the terminal device to access the shared access network device. It can also be understood as the PLMN identifier used when a device in a non-operator network (such as a terminal device in the second operator network) accesses a device in the operator network (such as an access network device in the first operator network).

Step 703: The second mobility management network element sends a second handover request message to the first mobility management network element according to the first handover request message.

The second switching request message may be used to request switching of the terminal device from the second-standard network in the second operator network to the first-standard network in the first operator network.

The first mobility management network element belongs to a first-standard network in a first operator network. For example, the first mobility management network element may be a vAMF.

In some embodiments, when the first switching request message includes a second switching reason value, and the second switching reason value is used to indicate that the terminal device switches from the second-standard network to the first-standard network, the second mobility management network element sends a second switching request message to the first mobility management network element.

For example, the second handover reason value may be an inter-system handover indication (inter system handover indication), and the inter-system handover indication is used to instruct the terminal device to switch from a 4G network to a 5G network.

In an optional implementation, in addition to the identifier of the target access network device and the second switching reason value, the first switching request message may also include one or more of the following information: MME UE context or source to target transparent container. The source to target transparent container can refer to the related description mentioned above.

Optionally, the MME UE context may contain international mobile subscriber identity (IMSI), mobile equipment identity (ME ID), UE security context (UE security context), UE network capability (UE network capability), aggregated maximum bit rate (AMBR), selected CN operator ID, access point name (APN) restriction, Serving GW address and TEID for control signalling, or EPS bearer context(s).

Before the second mobility management network element sends the second handover request message to the first mobility management network element, the second mobility management network element may generate a second handover request message according to the first handover request message.

The second switching request message may include the shared PLMN identifier and the information included in the first switching request message.

Exemplarily, the second mobility management network element may convert the EPS bearer context into a 5GS mobility management (mobility management, MM) context according to the MME UE context. At the same time, the second mobility management network element may request the hNRF to obtain the address or fully qualified domain name (FQDN) at the N11 or N16 interface of the SMF+PGW-C according to the S5 or S8 interface address and FQDN of the SMF+PGW-C included in the EPS PDN connection in the EPS bearer context, and include it in the 5GS MM context. Accordingly, the 5GS MM context included in the second handover request message no longer includes the EPS bearer context.

In an example, the second handover request message may further include second indication information, where the second indication information is used to instruct the first mobility management network element to forward the received handover completion notification message to the second mobility management network element.

In an optional implementation manner, the second mobility management network element may select the first mobility management function network element by the following method, and then send the second handover request message to the first mobility management network element:

Method b1: The second mobility management network element is based on the locally configured first mobility management network element corresponding to the target access network device.

In the method b1, the second mobility management network element is configured with a list of mobility management network elements supporting shared access network devices, and the second mobility management network element can select a first mobility management network element corresponding to the target access network device and belonging to the second operator network.

Method b2: The second mobility management network element queries the network storage network element for the identifier of the first mobility management network element.

In method b2, the first mobile management network element registers its own capability information of supporting shared access network devices and information of shared access network devices supported by the first mobile management network element with the network storage network element. For example, the information of shared access network devices supported by the first mobile management network element may include the corresponding shared PLMN identifier of the shared access network device and the identifier of the shared access network device corresponding to the shared PLMN identifier; or, may include a list of identifiers of the shared access network device and the shared PLMN corresponding to the list of identifiers of the shared access network device. Logo.

Based on this, the second mobility management network element may query the network storage network element for the first mobility management network element that supports the target access network device based on the identifier of the target access network device.

Step 704: The first mobility management network element determines, based on the second switching request message, that the terminal device is allowed to switch from the second-standard network in the second operator's network to the first-standard network in the first operator's network.

Since the second switching request message includes a shared PLMN identifier, the first mobile management network element determines, based on the second switching request message, that the terminal device is allowed to switch from the second-standard network in the second operator network to the first-standard network in the first operator network. The method may be: when there is an equivalent mapping relationship between the identifier of the second PLMN currently used by the terminal device and the shared PLMN identifier, the first mobile management network element determines that the terminal device is allowed to switch from the second-standard network in the second operator network to the first-standard network in the first operator network.

The second PLMN may be a PLMN used by subscribers of the second operator network to access the second operator network.

Optionally, an equivalent correspondence between the shared PLMN identifier and the identifier of the second PLMN is configured in the first mobility management network element.

Step 705: The first mobility management network element sends a session establishment request message to the first session management network element according to the second handover request message.

The first session management network element belongs to a first-standard network in a first operator network. For example, the first session management network element may be a vSMF.

Optionally, the session establishment request message may include 5GS MM context, etc.

After receiving the session establishment request message, the first session management network element can interact with the user plane network element and policy control network element in the first operator network based on the 5GS MM context to complete the establishment of the PDN session on the first operator network side, and the first session management network element interacts with hSMF+PGW-C, hUPF, etc. to complete the establishment of the session on the second operator network side. Afterwards, the first session management network element sends a session establishment response message to the first mobility management network element, and the session establishment response message is used to respond to the session establishment request message.

After receiving the session establishment response message, the first mobility management network element sends a first handover response message to the second mobility management network element, where the first handover response message is used to respond to the second handover request message.

Exemplarily, after receiving the session establishment response message, the first mobility management network element confirms the information of the PDU session established by the first session management network element and the corresponding EPS bearer setup list, and the first mobility management network element generates a first switching response message. The first switching response message may include a cause, a target to source transparent container, an EPS bearer setup List, and a target AMF ID. For the introduction of the cause and the target to source transparent container, please refer to the above-mentioned related description.

Furthermore, the second mobile management network element may record the target AMF ID, and upon receiving a switching completion message sent by the AMF corresponding to the target AMF ID, send a second switching response message to the third mobile management network element.

Optionally, when the second switching response message includes information about the indirect data forwarding path, the third mobility management network element may request the SGW to establish a downlink data forwarding path.

Further optionally, the third mobility management network element sends a switching command to the terminal device through the source access network device to trigger the terminal device to initiate a switching to the target access network device, so that the terminal device is reconfigured to the target access network device.

After the terminal device switches to the target access network device, the terminal device sends a switching completion notification message to the first mobile management network element through the shared access network device (i.e., the target access network device), and the switching completion notification message is used to notify the terminal device that it has switched to the first-standard network in the first operator network; the first mobile management network element sends the switching completion notification message to the second mobile management network element according to the second indication information included in the second switching request message.

Optionally, the handover completion notification message may include the identifier of the first mobility management network element. The second mobility management network element may compare the identifier of the first mobility management network element with the stored target AMF ID, and if they are the same, send a redirection handover completion notification message to the third mobility management network element. The redirection handover completion notification message may include a redirection complete notification indication (relocation complete notification indication), which can be used to indicate that the terminal device has successfully switched.

After receiving the redirection notification completion message, the third mobility management network element releases the EPS-related bearers. Then, the third mobility management network element sends a redirection completion confirmation message (relocation complete ack) to the second mobility management network element.

Afterwards, the second mobility management network element forwards the switching completion confirmation message to the first mobility management network element.

Through the above communication method, the switching request between different standards of the terminal device between the home operator network and the visited operator network can be converted into two steps: switching between different standards within the home operator network and switching between the same standard between the home operator network and the visited operator network. This can ensure that the terminal device maintains service continuity when moving from the second standard network of the home operator network to the first standard network of the visited operator network.

Based on the embodiment shown in FIG7 , FIG8 shows an example of a communication method. The first standard network is a 5G network, the second standard network is a 4G network, the shared access network device is a shared RAN, the source access network device is an eNB, the first mobile management network element is a vAMF, the second mobile management network element is a hAMF, and the third mobile management network element is a hMME. In this example, when the UE switches from the 4G network of the home operator to the 5G shared RAN of the visited operator, the hMME forwards the switching request message to the default configured hAMF according to the PLMN ID of the detected target gNB ID. The hAMF then selects a suitable vAMF and forwards the message to the corresponding vAMF, which determines whether to allow the UE to switch to the shared RAN based on the received information and its own capabilities. Then, the hAMF assists the hMME in interacting with the vAMF to complete the switching between the 4G network of the home operator and the 5G network of the visited operator and to ensure business continuity during the switching process. Exemplarily, the process of this example may include the following steps:

Step 801: the eNB sends a handover request message 1 to the hMME.

Among them, the switching request message 1 is used to request to switch the UE from the 4G network of the home operator network to the 5G network of the visited operator network.

The handover request message 1 contains the target gNB ID, the second handover reason value, MME UE context and source to target transparent container.

Among them, the meaning of each parameter in the switching request message 1 can be found in the relevant description involved in the embodiment described in Figure 7 above, and will not be repeated here.

Step 802: hMME sends a handover request message 1 to hAMF.

The handover request message 1 corresponds to the first handover request message in the embodiment described in FIG. 7 .

Exemplarily, a default hAMF is configured on the hMME. When the hMME receives the switching request message 1 from the eNB, the hMME confirms that the UE switches from the 4G network to the 5G network according to the second switching reason value, and the PLMN ID corresponding to the target gNB ID does not belong to the PLMN ID corresponding to the home operator network, and directly forwards the switching request message 1 to the default configured hAMF.

Step 803: hAMF determines, based on the handover request message 1, that the target access network device of the UE is a shared RAN, and the target access network device is used for the terminal device to access the first operator's network.

Exemplarily, hAMF determines the identifier of the first PLMN corresponding to the target gNB ID based on the target gNB ID in the switching request message 1. hAMF simultaneously queries hUDM for the subscription information of the UE, and determines, based on the subscription information obtained from hUDM, the corresponding shared PLMN ID used by the UE. If the identifier of the first PLMN corresponds to the shared PLMN ID, hAMF determines that the target access network device of the terminal device is the shared RAN.

Step 804: hAMF sends a switching request message 2 to vAMF according to the switching request message 1.

Among them, the switching request message 1 corresponds to the second switching request message in the embodiment described in FIG. 7 . For details, please refer to the description of the second switching request message, which will not be described in detail here.

Step 805: The vAMF determines, based on the handover request message 2, that the UE is allowed to switch from the 4G network in the home operator network to the 5G network in the visited operator network.

Among them, the method for vAMF to determine, based on the switching request message 2, that the UE is allowed to switch from the 4G network in the home operator network to the 5G network in the visited operator network can be referred to the relevant method involved in the embodiment shown in Figure 7, which is not described in detail here.

Optionally, when vAMF finds that the target gNB ID is not within its service range, it can query NRF for a vAMF that supports the target gNB ID and shared PLMN ID based on the target gNB ID and shared PLMN ID, and forward the switching request message 2 to the queried vAMF.

The correspondence between the shared PLMN ID and the PLMN ID of the home operator network is configured in vAMF.

Step 806: vAMF sends a session establishment request message to vSMF according to the switching request message 2.

Optionally, vAMF may select a vSMF, for example, it may select a default vSMF preconfigured on the vSMF for handling UE sessions, or select a suitable vSMF based on information such as the slice information carried in the 5GS MM context, or request NRF to select a vSMF that can interact with hSMF+PGW-C based on the hSMF+PGW-C N11 or N16 interface address or FQDN information carried in the 5GS MM context.

The session establishment request message can carry 5GS MM context.

Step 807: vSMF completes the preparation for switching to the visited operator network.

Illustratively, based on carrying 5GS MM context, vSMF interacts with network elements on the visited operator network side, such as vUPF and vPCF, to complete the establishment of the PDN session on the visited operator network side, and vSMF interacts with hSMF+PGW-C, hUPF, etc. to complete the establishment of the session on the home operator side.

Step 808: vSMF sends a session establishment response message to vAMF.

Step 809: vAMF sends a handover response message 1 to hAMF.

The switching response message 1 is used to respond to the switching request message 2 .

Exemplarily, after receiving the session establishment response message, vAMF confirms the information of the PDU session established by vSMF and the corresponding EPS bearer setup list, and vAMF generates a switching response message 1. The switching response message 1 may include a cause, a target to source transparent container, an EPS bearer setup List, and a target AMF ID.

Step 810: hAMF records the target AMF ID, and upon receiving the switching completion message sent by the AMF corresponding to the target AMF ID, it sends a switching response message 2 to hMME.

Optionally, hAMF also forwards the handover completion message sent by the AMF to hMME.

Step 811: hMME sends a handover command to the eNB to trigger the UE to handover to the target access network device.

Optionally, when the handover response message 2 includes information about the indirect data forwarding path, the hMME may request the SGW to establish a downlink data forwarding path.

Step 812: the eNB sends a handover command to the UE, and the UE initiates a handover process to the shared RAN.

Step 813: After the UE switches to the target access network device, the UE sends a switching completion notification message to the vAMF through the shared RAN (i.e., the target access network device). The switching completion notification message is used to notify the UE that it has switched to the 5G network in the visited operator network.

Step 814: vAMF sends the switching completion notification message to hAMF according to the second indication information included in the switching request message 2.

Optionally, the vAMF ID may be included in the switch completion notification message.

Step 815: After hAMF receives the switching completion notification message sent by vAMF, it compares the vAMF ID with the stored target AMF ID. If they are the same, it sends a switching completion notification message to hMME.

Step 816: After receiving the handover completion notification message sent by hAMF, hMME releases EPS-related bearers. Then, hMME sends a handover completion confirmation message to hAMF.

Step 817: hAMF forwards the switching completion confirmation message to vAMF.

Based on the above method, it is possible to ensure that service continuity is maintained when the UE moves from the 4G network of the home operator network to the 5G network of the visited operator network.

In addition to the communication method shown in Figures 7 and 8 above, the embodiment of the present application also provides a communication method shown in Figures 9 and 10, which can ensure that the UE maintains service continuity when moving from the 4G network of the home operator network to the 5G network of the visited operator network.

In the example shown in Figure 9, when the UE switches from the 4G network of the home operator network to the 5G network of the visited operator network, the hAMF assists in forwarding the handover request received by the hMME to the vAMF, and the vAMF determines that the UE is allowed to initiate a handover to the 5G network of the visited operator network, and forwards the handover preparation completion message and confirmation message to the hMME through the hAMF, completing the handover of the UE from the 4G network of the home operator network to the 5G network of the visited operator network. Exemplarily, the process of this example may include the following steps:

Step 901: the eNB sends a handover request message 1 to the hMME.

Among them, the switching request message 1 is used to request to switch the UE from the 4G network of the home operator network to the 5G network of the visited operator network.

The handover request message 1 contains the target gNB ID, the second handover reason value, MME UE context and source to target transparent container.

Among them, the meaning of each parameter in the switching request message 1 can be found in the relevant description involved in the embodiment described in Figure 7 above, and will not be repeated here.

Step 902: hMME sends a handover request message 1 to hAMF.

Exemplarily, a default hAMF is configured on the hMME. When the hMME receives the switching request message 1 from the eNB, the hMME confirms that the UE switches from the 4G network to the 5G network according to the second switching reason value, and the PLMN ID corresponding to the target gNB ID does not belong to the PLMN ID corresponding to the home operator network, and directly forwards the switching request message 1 to the default configured hAMF.

Step 903: hAMF encapsulates the switching request message 1 into the N14 container, and sends a redirected switching request message (such as an N14 message) to the vAMF. The redirected switching request message includes the N14 container.

Exemplarily, hAMF determines that the UE switches from 4G to 5G according to the second switching reason value in the switching request message 1, and determines that the switching request message 1 needs to be forwarded to vAMF. Among them, vAMF is the AMF corresponding to the PLMN ID corresponding to the target gNB ID.

Optionally, hAMF is configured with the correspondence between the PLMN ID of the visited operator network and vAMF.

The redirection switching request message includes a forward indication (forward_indication), which is used to instruct the vAMF to forward the switching completion notification message to the hAMF after receiving it.

Step 904: vAMF parses the redirected switching request message to obtain the switching request message 1 encapsulated in the N14 container, and Request message 1 to determine whether the UE is allowed to switch from the 4G network in the home operator network to the 5G network in the visited operator network.

Exemplarily, vAMF determines the identifier of the first PLMN corresponding to the target gNB ID according to the target gNB ID in the handover request message 1. vAMF also queries the subscription information of the UE from hUDM, and determines the corresponding shared PLMN ID used by the UE according to the subscription information obtained from hUDM. If the identifier of the first PLMN corresponds to the shared PLMN ID, vAMF determines that the target access network device of the terminal device is the shared RAN. Optionally, vAMF confirms that it supports the UE to switch from the 4G network of the home operator to the 5G network of the visited operator by querying the local configuration.

Optionally, the vAMF is configured with the correspondence between the shared PLMN ID and the PLMN ID of the home operator network. The vAMF determines that the shared PLMN and the PLMN of the home operator network are equivalent PLMNs through the correspondence between the shared PLMN ID and the PLMN ID of the home operator network, thereby determining that the UE is allowed to switch from the 4G network in the home operator network to the 5G network in the visited operator network.

According to the MME UE context parsed in the handover request message 1, vAMF sends a request for 5GS context to hAMF (proxy), which carries the MME UE context. hAMF (proxy) converts EPS context into 5GS MM context according to the MME UE context. Among them, hAMF can request hNRF to obtain the address or FQDN of the N11 or N16 interface of SMF+PGW-C according to the S5 or S8 interface address and FQDN of SMF+PGW-C included in the EPS PDN connection in the EPS context, and include it in the 5GS MM context.

Step 905: vAMF sends a session establishment request message to vSMF.

Optionally, vAMF may select a vSMF, for example, it may select a default vSMF preconfigured on the vSMF for handling UE sessions, or select a suitable vSMF based on information such as the slice information carried in the 5GS MM context, or request NRF to select a vSMF that can interact with hSMF+PGW-C based on the hSMF+PGW-C N11 or N16 interface address or FQDN information carried in the 5GS MM context.

The session establishment request message can carry 5GS MM context.

Step 906: vSMF completes the preparation for switching to the visited operator network.

Illustratively, based on carrying 5GS MM context, vSMF interacts with network elements on the visited operator network side, such as vUPF and vPCF, to complete the establishment of the PDN session on the visited operator network side, and vSMF interacts with hSMF+PGW-C, hUPF, etc. to complete the establishment of the session on the home operator side.

Step 907: vSMF sends a session establishment response message to vAMF.

Step 908: vAMF generates a switching response message 1, encapsulates the switching response message 1 in an N14 container, and sends the N14 message 1 to the hAMF, where the N14 message 1 includes the N14 container.

The switching response message 1 is used to respond to the switching request message 1 .

Exemplarily, after receiving the session establishment response message, vAMF confirms the information of the PDU session established by vSMF and the corresponding EPS bearer setup list, and vAMF generates a switching response message 1. The switching response message 1 may include a cause, a target to source transparent container, an EPS bearer setup List, and a target AMF ID.

Step 909: hAMF parses N14 message 1, records the target AMF ID in the switching response message 1, and forwards the switching response message 1 to hMME.

Step 910: hMME sends a handover command to the eNB to trigger the UE to handover to the target access network device.

Step 911: the eNB sends a handover command to the UE, and the UE initiates a handover process to the shared RAN.

Step 912: After the UE switches to the target access network device, the UE sends a switching completion notification message to the vAMF through the shared RAN (ie, the target access network device).

Among them, the switching completion notification message is used to notify the UE that it has switched to the 5G network in the visited operator's network.

Step 913: vAMF encapsulates the switching completion notification message in an N14 container according to the forwarding indication included in the redirected switching request message, and sends N14 message 2 to hAMF.

The N14 message 2 includes the N14 container.

Step 914: After hAMF parses N14 message 2 to obtain the switching completion notification message, it compares the vAMF ID with the stored target AMF ID. If they are the same, it sends a switching completion notification message to hMME.

Step 915: After receiving the handover completion notification message sent by hAMF, hMME releases EPS-related bearers. Then, hMME sends a handover completion confirmation message to hAMF.

Step 916: hAMF encapsulates the handover completion confirmation message sent by hMME in an N14 container, and sends N14 message 3 to vAMF, where N14 message 3 includes the N14 container.

Based on the above method, it can be ensured that the UE is kept stable when moving from the 4G network of the home operator network to the 5G network of the visited operator network. ways to maintain business continuity.

In the example shown in Figure 10, when the UE moves from the 4G network of the home operator network to the 5G network of the visited operator network, the context of its mobility management is saved in hAMF. This example uses vAMF as a proxy to pass messages between the shared RAN and hAMF. After receiving the switching request message sent by hMME, hAMF selects vSMF according to the message instruction, and forwards the PDU session creation message generated by hAMF to the selected vSMF. hAMF establishes a connection with vSMF through vAMF to establish a PDU session on the visited operator network side. Exemplarily, the process of this example may include the following steps:

Step 1001: the eNB sends a handover request message 1 to the hMME.

Among them, the switching request message 1 is used to request to switch the UE from the 4G network of the home operator network to the 5G network of the visited operator network.

The handover request message 1 contains the target gNB ID, the second handover reason value, MME UE context and source to target transparent container.

Among them, the meaning of each parameter in the switching request message 1 can be found in the relevant description involved in the embodiment described in Figure 7 above, and will not be repeated here.

Step 1002: hMME sends a handover request message 1 to hAMF.

Exemplarily, a default hAMF is configured on the hMME. When the hMME receives the switching request message 1 from the eNB, the hMME confirms that the UE switches from the 4G network to the 5G network according to the second switching reason value, and the PLMN ID corresponding to the target gNB ID does not belong to the PLMN ID corresponding to the home operator network, and directly forwards the switching request message 1 to the default configured hAMF.

Step 1003: hAMF generates a session establishment request message according to the switching request message 1, encapsulates the session establishment request message in an N14 container, and sends the N14 message 1 to the vAMF.

The N14 message 1 includes the N14 container.

hAMF determines that the UE switches from the 4G network to the 5G network based on the second switching reason value in the switching request message 1, and then determines the PLMN ID corresponding to the target gNB ID based on the target gNB ID in the switching request message 1, and selects the vAMF corresponding to the PLMN ID corresponding to the target gNB ID based on the correspondence between the PLMN ID of the visited operator network configured on the hAMF and the vAMF.

hAMF converts EPS context into 5GS MM context according to MME UE context in handover request message 1. For example, hAMF can request hNRF to obtain the address or FQDN at the N11 or N16 interface of SMF+PGW-C according to the S5 or S8 interface address and FQDN of SMF+PGW-C included in the EPS PDN connection in EPS context, and include it in 5GS MM context. In addition, hAMF requests the ID of v-SMF according to the target gNB ID through hNRF and vNRF.

The session establishment request message can carry 5GS MM context.

Optionally, the N14 message 1 may also include the ID of the v-SMF and a forwarding indication (forward_indication), where the forwarding indication is used to instruct the vAMF to forward the received message to the v-SMF or hAMF.

Step 1004: vAMF parses the N14 message, and sends the session establishment request message in the N14 container to the v-SMF corresponding to the v-SMF ID according to the forwarding instruction in the N14 message 1.

Step 1005: vSMF completes the preparation for switching to the visited operator network.

Step 1006: vSMF sends a session establishment response message to vAMF.

For example, the session establishment response message can be a PDU session context response (Nsmf_PDUSession_CreateSMContext response).

Step 1007: After receiving the session establishment response message sent by vSMF, vAMF encapsulates the session establishment response message into an N14 container, and sends an N14 message 2 to hAMF according to the forwarding instruction in the N14 message 1, and N14 message 2 includes the N14 container.

Step 1008: After parsing N14 message 2, hAMF obtains a session establishment response message, interacts with network elements on the visited operator network side (such as v-SMF and vUPF) and network elements on the home operator network side (such as hSMF+PGW-C and hUPF), completes the switching preparation for 5GS, and sends a switching response message to hMME. The switching response message is used to respond to the switching request message 1.

Step 1009: hMME sends a handover command to the eNB to trigger the UE to switch to the target access network device to initiate handover.

Step 1010: the eNB sends a handover command to the UE, and the UE initiates a handover process to the shared RAN.

Step 1011: After the UE switches to the target access network device, the UE sends a switching completion notification message to the vAMF through the shared RAN (i.e., the target access network device). The switching completion notification message is used to notify the UE that it has switched to the 5G network in the visited operator network.

Step 1012: vAMF encapsulates the switching completion notification message in an N14 container and sends an N14 message 3 to hAMF, where the N14 message 3 includes the N14 container.

Step 1013: After hAMF parses N14 message 3 to obtain a handover completion notification message, it sends a handover completion notification message to hMME.

Step 1014: After receiving the handover completion notification message sent by the hAMF, the hMME releases the EPS-related bearers. After that, the hMME sends a handover completion confirmation message to the hAMF.

Step 1015: hAMF encapsulates the handover completion confirmation message sent by hMME in an N14 container, and sends N14 message 4 to vAMF, where N14 message 4 includes the N14 container.

Based on the above method, it is possible to ensure that service continuity is maintained when the UE moves from the 4G network of the home operator network to the 5G network of the visited operator network.

Based on the above embodiments, the embodiments of the present application further provide a communication device, as shown in FIG11 , the communication device 1100 may include a transceiver unit 1101 and a processing unit 1102. The transceiver unit 1101 is used for the communication device 1100 to receive messages (information or data) or send messages (information or data), and the processing unit 1102 is used to control and manage the actions of the communication device 1100. The processing unit 1102 may also control the steps performed by the transceiver unit 1101.

Exemplarily, the communication device 1100 may specifically be the first mobile management network element in the above-mentioned embodiment, the processor of the first mobile management network element, or a chip, or a chip system, or a functional module, etc.; or, the communication device 1100 may specifically be the second mobile management network element in the above-mentioned embodiment, the processor of the second mobile management network element, or a chip, or a chip system, or a functional module, etc.

In one embodiment, when the communication device 1100 is used to implement the function of the first mobility management network element in the embodiment shown in Figure 3 or Figure 4 above: the transceiver unit 1101 can be used to receive a first switching request message from the first access network device, and the first switching request message is used to request that the terminal device be switched from the first standard network in the first operator network to the second standard network in the second operator network; the first access network device is a shared access network device, and the terminal device accesses the first standard network in the first operator network through the first access network device; the processing unit 1102 can be used to determine, according to the first switching request message, that the terminal device is allowed to switch from the first standard network in the first operator network to the second standard network in the second operator network; the transceiver unit 1101 can also be used to send a second switching request message to the second mobility management network element, and the second switching request message is used to request that the terminal device be switched from the first standard network in the first operator network to the second standard network in the second operator network; wherein the first mobility management network element belongs to the first standard network in the first operator network, and the second mobility management network element belongs to the first standard network in the second operator network.

In an optional embodiment, the first switching request message includes an identifier of the first PLMN currently used by the terminal device. When the processing unit 1102 determines that the terminal device is allowed to switch from the first-standard network in the first operator network to the second-standard network in the second operator network based on the first switching request message, it can be used to: determine that the identifier of the first PLMN is a shared PLMN identifier of the second operator network, and the shared PLMN identifier is used for users of the second operator network to access a shared access network device of the first operator network.

Furthermore, the first switching request message also includes an identifier of a target access network device of the terminal device; the processing unit 1102 can also be used to: determine, based on the identifier of the target access network device, an identifier of a second PLMN to which the target access network device belongs, the second PLMN corresponding to the second operator network; when the processing unit 1102 determines that the identifier of the first PLMN is a shared PLMN identifier of the second operator network, it can be used to: determine, based on the identifier of the first PLMN and the identifier of the second PLMN, that the first PLMN and the second PLMN are equivalent PLMNs.

Exemplarily, when the processing unit 1102 determines that the first PLMN and the second PLMN are equivalent PLMNs according to the identifier of the first PLMN and the identifier of the second PLMN, it can be used to: determine that there is an equivalent mapping relationship between the identifier of the first PLMN and the identifier of the second PLMN.

In a possible manner, the processing unit 1102 may also be configured to: generate the second switching request message according to the first switching request message before the transceiver unit 1101 sends the second switching request message to the second mobility management network element.

Optionally, when generating the second switching request message based on the first switching request message, the processing unit 1102 can be used to: generate the second switching request message, the second switching request message including the identifier of the second PLMN and information in the first switching request message except the identifier of the first PLMN.

In one example, when the transceiver unit 1101 sends a second switching request message to a second mobile management network element, it can be used to: when the first switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from the first standard network to the second standard network, send the second switching request message to the second mobile management network element.

In one embodiment, the second switching request message includes the first switching reason value.

In a possible manner, the second handover request message includes first indication information, and the first indication information is used to instruct the second mobility management network element to forward the received handover completion notification message to the first mobility management network element.

In another embodiment, when the communication device 1100 is used to implement the function of the second mobility management network element in the embodiment shown in FIG. 3 or FIG. 4 above: the transceiver unit 1101 can be used to receive a second switching request message from the first mobility management network element, the second switching request message is used to request to switch the terminal device from the first standard network in the first operator network to the second standard network in the second operator network; and according to the second switching request message, send a third switching request message to the third mobility management network element, the third switching request message is used to request to switch the terminal device from the first standard network in the first operator network to the second standard network in the second operator network; wherein the first mobility management network element belongs to the first standard network in the first operator network, the second mobility management network element belongs to the first standard network in the second operator network, and the third mobility management network element belongs to the second standard network in the second operator network. The processing unit 1102 can be used to control the operation of the transceiver unit 1101.

In an optional embodiment, when the transceiver unit 1101 sends the third switching request message to the third mobile management network element according to the second switching request message, it can be used to: when the second switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from the first-standard network to the second-standard network, send the third switching request message to the third mobile management network element.

In one example, the second switching request message includes first indication information, and the first indication information is used to instruct the second mobile management network element to send the received switching completion notification message to the first mobile management network element; the transceiver unit 1101 can also be used to: receive a switching completion notification message from the third mobile management network element, and the switching completion notification message is used to notify the terminal device that it has switched to the second-standard network in the second operator network; according to the first indication information, send the switching completion notification message to the first mobile management network element.

Optionally, the second switching request message includes an identifier of a second PLMN, and the identifier of the second PLMN is used to identify the PLMN to which the target access network device of the terminal device belongs.

In another embodiment, when the communication device 1100 is used to implement the function of the second mobility management network element in the embodiment shown in Figure 7 or Figure 8 above: the transceiver unit 1101 can be used to receive a first switching request message from the third mobility management network element, and the first switching request message is used to request that the terminal device be switched from the second standard network in the second operator network to the first standard network in the first operator network; the processing unit 1102 can be used to determine, according to the first switching request message, that the target access network device of the terminal device is a shared access network device, and the target access network device is used for the terminal device to access the first operator network; the transceiver unit 1101 can also be used to send a second switching request message to the first mobility management network element according to the first switching request message, and the second switching request message is used to request that the terminal device be switched from the second standard network in the second operator network to the first standard network in the first operator network; wherein the first mobility management network element belongs to the first standard network in the first operator network, the second mobility management network element belongs to the first standard network in the second operator network, and the third mobility management network element belongs to the second standard network in the second operator network.

In an optional embodiment, the first switching request message includes an identifier of the target access network device; when the processing unit 1102 determines that the target access network device of the terminal device is a shared access network device based on the first switching request message, it can be used to: determine, based on the identifier of the target access network device, an identifier of the first PLMN to which the target access network device belongs, the first PLMN corresponding to the first operator network; if the identifier of the first PLMN corresponds to a shared PLMN identifier, determine that the target access network device of the terminal device is the shared access network device; wherein the shared PLMN identifier is used for users of the second operator network to access the shared access network device of the first operator network.

In one example, when the transceiver unit 1101 sends a second switching request message to the first mobile management network element according to the first switching request message, it can be used to: when the first switching request message includes a second switching reason value, and the second switching reason value is used to indicate that the terminal device switches from the second-standard network to the first-standard network, send the second switching request message to the first mobile management network element.

Optionally, the processing unit 1102 can also be used to: generate the second switching request message according to the first switching request message before the transceiver unit 1101 sends the second switching request message to the first mobile management network element, wherein the second switching request message includes the shared PLMN identifier and the information included in the first switching request message.

Exemplarily, the second handover request message includes second indication information, and the second indication information is used to instruct the first mobility management network element to forward the received handover completion notification message to the second mobility management network element.

In another embodiment, when the communication device 1100 is used to implement the function of the first mobility management network element in the embodiment shown in Figure 7 or Figure 8 above: the transceiver unit 1101 can be used to receive a second switching request message from the second mobility management network element, and the second switching request message is used to request that the terminal device be switched from the second standard network in the second operator network to the first standard network in the first operator network; the processing unit 1102 can be used to determine, according to the second switching request message, whether the terminal device is allowed to switch from the second standard network in the second operator network to the first standard network in the first operator network. The second-standard network is switched to the first-standard network in the first operator network; the transceiver unit 1101 can also be used to send a session establishment request message to the first session management network element according to the second switching request message; wherein the first mobile management network element belongs to the first-standard network in the first operator network, the second mobile management network element belongs to the first-standard network in the second operator network, and the first session management network element belongs to the first-standard network in the first operator network.

In some embodiments, the second switching request message includes a shared PLMN identifier, and the shared PLMN identifier is used for users of the second operator network to access the shared access network device of the first operator network; when the processing unit 1102 determines, based on the second switching request message, that the terminal device is allowed to switch from the second-standard network in the second operator network to the first-standard network in the first operator network, it can be used to: when there is an equivalent mapping relationship between the identifier of the second PLMN currently used by the terminal device and the shared PLMN identifier, determine that the terminal device is allowed to switch from the second-standard network in the second operator network to the first-standard network in the first operator network.

In an optional implementation, the second switching request message includes second indication information, and the second indication information is used to instruct the first mobile management network element to forward the received switching completion notification message to the second mobile management network element; the transceiver unit 1101 can also be used to: receive a switching completion notification message, and the switching completion notification message is used to notify the terminal device that it has switched to the first standard network in the first operator network; according to the second indication information, send the switching completion notification message to the second mobile management network element.

It should be noted that the division of units in the embodiments of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation. Each functional unit in the embodiments of the present application may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) or a processor (processor) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

Based on the above embodiments, the embodiments of the present application further provide a communication device. Referring to FIG. 12 , the communication device 1200 may include a memory 1201 and a processor 1202 .

Specifically, the processor 1202 may be a central processing unit (CPU), a network processor (NP) or a combination of a CPU and a NP. The processor 1202 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD) or a combination thereof. The PLD may be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL) or any combination thereof.

Among them, the memory 1201 and the processor 1202 are interconnected. Optionally, the memory 1201 and the processor 1202 are interconnected via a bus 1203; the bus 1203 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, FIG12 is represented by only one thick line, but it does not mean that there is only one bus or one type of bus.

In an optional implementation, the memory 1201 is used to store instructions, etc. The memory 1201 may include RAM, and may also include non-volatile memory (non-volatile memory), such as one or more disk memories. The processor 1202 executes the computer instructions stored in the memory 1201 to implement the above functions, thereby realizing the functions of the communication device 1200.

Optionally, the communication device 1200 may further include a transceiver, wherein the processor 1202 may control the transceiver to receive and send messages, information or data, etc. The specific figure is not shown again.

Exemplarily, the communication device 1200 may specifically be the first mobility management network element in the above embodiment; or, the communication device 1200 may specifically be the second mobility management network element in the above embodiment.

In one embodiment, when the communication device 1200 implements the function of the first mobility management network element in the embodiment shown in FIG. 3 or FIG. 4, the processor 1202 may call the computer instructions in the memory 1201 to implement the first mobile management network element in the embodiment shown in FIG. 3 or FIG. 4. The operations performed by the management network element. For specific related descriptions, please refer to the related descriptions in the embodiments shown in FIG. 3 or FIG. 4 above, which will not be described in detail here.

In another embodiment, when the communication device 1200 implements the function of the second mobility management network element in the embodiment shown in FIG. 3 or FIG. 4, the processor 1202 may call the computer instructions in the memory 1201 to implement the operation performed by the second mobility management network element in the embodiment shown in FIG. 3 or FIG. 4. For specific related descriptions, please refer to the related descriptions in the embodiment shown in FIG. 3 or FIG. 4, which will not be described in detail here.

In another embodiment, when the communication device 1200 implements the function of the first mobility management network element in the embodiment shown in FIG. 7 or FIG. 8, the processor 1202 may call the computer instructions in the memory 1201 to implement the operation performed by the first mobility management network element in the embodiment shown in FIG. 7 or FIG. 8. For specific related descriptions, please refer to the related descriptions in the embodiment shown in FIG. 7 or FIG. 8, which will not be described in detail here.

In another embodiment, when the communication device 1200 implements the function of the second mobility management network element in the embodiment shown in FIG. 7 or FIG. 8, the processor 1202 may call the computer instructions in the memory 1201 to implement the operation performed by the second mobility management network element in the embodiment shown in FIG. 7 or FIG. 8. For specific related descriptions, please refer to the related descriptions in the embodiment shown in FIG. 7 or FIG. 8, which will not be described in detail here.

Based on the above embodiments, an embodiment of the present application provides a communication system, which may include the first mobility management network element and the second mobility management network element involved in the above embodiments.

An embodiment of the present application also provides a computer-readable storage medium, which is used to store instructions. When the instructions are executed by a computer, the computer can implement the communication method provided by the above method embodiment.

An embodiment of the present application also provides a computer program product, which is used to store instructions. When the instructions are executed by a computer, the computer can implement the communication method provided by the above method embodiment.

An embodiment of the present application also provides a chip, including a processor, wherein the processor is coupled to a memory and is used to call instructions in the memory so that the chip implements the communication method provided in the above method embodiment.

An embodiment of the present application also provides a chip, which is coupled to a memory and is used to implement the communication method provided in the above method embodiment.

Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing instructions.

The present application is described with reference to the flowchart and/or block diagram of the method, device (system), and computer program product according to the present application. It should be understood that each flow and/or box in the flow chart and/or block diagram, as well as the combination of the flow chart and/or box in the flow chart and/or block diagram can be implemented by instructions. These instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the function specified in one flow chart or multiple flows and/or one box or multiple boxes in the block diagram.

These instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

These instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims (28)

A communication method, comprising: The first mobility management network element receives a first switching request message from a first access network device, where the first switching request message is used to request that a terminal device be switched from a first-standard network in a first operator network to a second-standard network in a second operator network; the first access network device is a shared access network device, and the terminal device accesses the first-standard network in the first operator network through the first access network device; The first mobility management network element determines, according to the first switching request message, that the terminal device is allowed to switch from the first-standard network in the first operator network to the second-standard network in the second operator network; The first mobility management network element sends a second switching request message to the second mobility management network element, where the second switching request message is used to request switching of the terminal device from the first-standard network in the first operator network to the second-standard network in the second operator network; The first mobility management network element belongs to the first-standard network in the first operator network, and the second mobility management network element belongs to the first-standard network in the second operator network. The method according to claim 1, wherein the first switching request message includes an identifier of a first public land mobile network PLMN currently used by the terminal device, and the first mobility management network element determines, according to the first switching request message, that the terminal device is allowed to switch from the first standard network in the first operator network to the second standard network in the second operator network, comprising: The first mobility management network element determines that the identifier of the first PLMN is a shared PLMN identifier of the second operator network, and the shared PLMN identifier is used for users of the second operator network to access a shared access network device of the first operator network. The method according to claim 2, characterized in that the first switching request message also includes an identifier of a target access network device of the terminal device; the method further includes: The first mobility management network element determines, according to the identifier of the target access network device, an identifier of a second PLMN to which the target access network device belongs, where the second PLMN corresponds to the second operator network; The first mobility management network element determines that the identifier of the first PLMN is a shared PLMN identifier of the second operator network, including: The first mobility management network element determines, according to the identifier of the first PLMN and the identifier of the second PLMN, that the first PLMN and the second PLMN are equivalent PLMNs. The method according to claim 3, wherein the first mobility management network element determines, based on the identifier of the first PLMN and the identifier of the second PLMN, that the first PLMN and the second PLMN are equivalent PLMNs, comprising: The first mobility management network element determines that there is an equivalent mapping relationship between the identifier of the first PLMN and the identifier of the second PLMN. The method according to claim 3 or 4, characterized in that before the first mobility management network element sends the second handover request message to the second mobility management network element, the method further comprises: The first mobility management network element generates the second handover request message according to the first handover request message. The method according to claim 5, wherein the first mobility management network element generates the second handover request message according to the first handover request message, comprising: The first mobility management network element generates the second handover request message, where the second handover request message includes the identifier of the second PLMN and information in the first handover request message except the identifier of the first PLMN. The method according to any one of claims 1 to 6, wherein the first mobility management network element sends a second handover request message to the second mobility management network element, comprising: When the first switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from the first-standard network to the second-standard network, the first mobility management network element sends the second switching request message to the second mobility management network element. The method as claimed in claim 7 is characterized in that the second switching request message includes the first switching reason value. The method according to any one of claims 1-8 is characterized in that the second switching request message includes first indication information, and the first indication information is used to instruct the second mobility management network element to forward the received switching completion notification message to the first mobility management network element. A communication method, comprising: The second mobility management network element receives a second switching request message from the first mobility management network element, where the second switching request message is used to request switching of the terminal device from a first-standard network in the first operator network to a second-standard network in the second operator network; The second mobility management network element sends a third switching request message to a third mobility management network element according to the second switching request message, where the third switching request message is used to request switching of the terminal device from the first-standard network in the first operator network to the second-standard network in the second operator network; Among them, the first mobility management network element belongs to the first-standard network in the first operator network, the second mobility management network element belongs to the first-standard network in the second operator network, and the third mobility management network element belongs to the second-standard network in the second operator network. The method according to claim 10, wherein the second mobility management network element sends the third handover request message to the third mobility management network element according to the second handover request message, comprising: When the second switching request message includes a first switching reason value, and the first switching reason value is used to indicate that the terminal device switches from the first-standard network to the second-standard network, the second mobility management network element sends the third switching request message to the third mobility management network element. The method according to claim 10 or 11, characterized in that the second handover request message includes first indication information, and the first indication information is used to instruct the second mobility management network element to send the received handover completion notification message to the first mobility management network element; the method further includes: The second mobility management network element receives a switching completion notification message from the third mobility management network element, where the switching completion notification message is used to notify the terminal device that the terminal device has switched to the second-standard network in the second operator network; The second mobility management network element sends the switching completion notification message to the first mobility management network element according to the first indication information. The method according to any one of claims 10-12 is characterized in that the second switching request message includes an identifier of a second PLMN, and the identifier of the second PLMN is used to identify the PLMN to which the target access network device of the terminal device belongs. A communication method, comprising: The second mobility management network element receives a first switching request message from the third mobility management network element, where the first switching request message is used to request switching of the terminal device from the second-standard network in the second operator network to the first-standard network in the first operator network; The second mobility management network element determines, according to the first switching request message, that a target access network device of the terminal device is a shared access network device, and the target access network device is used for the terminal device to access the first operator network; The second mobility management network element sends a second switching request message to the first mobility management network element according to the first switching request message, where the second switching request message is used to request switching of the terminal device from the second-standard network in the second operator network to the first-standard network in the first operator network; Among them, the first mobility management network element belongs to the first-standard network in the first operator network, the second mobility management network element belongs to the first-standard network in the second operator network, and the third mobility management network element belongs to the second-standard network in the second operator network. The method according to claim 14, wherein the first handover request message includes an identifier of the target access network device; and the second mobility management network element determines that the target access network device of the terminal device is a shared access network device according to the first handover request message, comprising: The second mobility management network element determines, according to the identifier of the target access network device, an identifier of a first PLMN to which the target access network device belongs, where the first PLMN corresponds to the first operator network; If the identifier of the first PLMN corresponds to the shared PLMN identifier, the second mobility management network element determines that the target access network device of the terminal device is the shared access network device; The shared PLMN identifier is used for users of the second operator network to access a shared access network device of the first operator network. The method according to claim 14 or 15, characterized in that the second mobility management network element sends a second handover request message to the first mobility management network element according to the first handover request message, comprising: When the first switching request message includes a second switching reason value, and the second switching reason value is used to indicate that the terminal device switches from the second-standard network to the first-standard network, the second mobility management network element sends the second switching request message to the first mobility management network element. The method according to claim 15, characterized in that before the second mobility management network element sends the second handover request message to the first mobility management network element, the method further comprises: The second mobility management network element generates the second handover request message according to the first handover request message, where the second handover request message includes the shared PLMN identifier and the information included in the first handover request message. The method as described in any one of claims 14-17 is characterized in that the second switching request message includes second indication information, and the second indication information is used to instruct the first mobility management network element to forward the received switching completion notification message to the second mobility management network element. A communication method, comprising: The first mobility management network element receives a second switching request message from the second mobility management network element, where the second switching request message is used to request switching of the terminal device from the second-standard network in the second operator network to the first-standard network in the first operator network; The first mobility management network element determines, according to the second switching request message, that the terminal device is allowed to switch from the second-standard network in the second operator network to the first-standard network in the first operator network; The first mobility management network element sends a session establishment request message to the first session management network element according to the second handover request message; Among them, the first mobility management network element belongs to the first-standard network in the first operator network, the second mobility management network element belongs to the first-standard network in the second operator network, and the first session management network element belongs to the first-standard network in the first operator network. The method according to claim 19, wherein the second switching request message includes a shared PLMN identifier, and the shared PLMN identifier is used for users of the second operator network to access a shared access network device of the first operator network; the first mobility management network element determines, according to the second switching request message, that the terminal device is allowed to switch from the second-standard network in the second operator network to the first-standard network in the first operator network, comprising: When there is an equivalent mapping relationship between the identifier of the second PLMN currently used by the terminal device and the shared PLMN identifier, the first mobile management network element determines to allow the terminal device to switch from the second-standard network in the second operator network to the first-standard network in the first operator network. The method according to claim 19 or 20, characterized in that the second handover request message includes second indication information, and the second indication information is used to instruct the first mobility management network element to forward the received handover completion notification message to the second mobility management network element; the method further includes: The first mobility management network element receives a switching completion notification message, where the switching completion notification message is used to notify the terminal device that the terminal device has switched to the first-standard network in the first operator network; The first mobility management network element sends the switching completion notification message to the second mobility management network element according to the second indication information. A communication device, characterized in that it comprises a module or unit for executing the method as described in any one of claims 1 to 9, or comprises a module or unit for executing the method as described in any one of claims 19 to 21. A communication device, characterized by comprising a module or unit for executing the method as claimed in any one of claims 10 to 13, or comprising a module or unit for executing the method as claimed in any one of claims 14 to 18. A communication device, comprising a memory and a processor, wherein: The memory is used to store computer instructions; The processor is coupled to the memory and is configured to call computer instructions in the memory to execute the method according to any one of claims 1-21. A computer-readable storage medium, characterized in that instructions are stored in the computer-readable storage medium, and when the instructions are called by a computer, the method according to any one of claims 1 to 21 is executed. A computer program product, characterized in that it contains instructions, and when the instructions are run on a computer, the method according to any one of claims 1 to 21 is executed. A chip, characterized in that the chip is coupled to a memory and is used to read and execute instructions stored in the memory to implement the method as described in any one of claims 1-21. A communication system, characterized by comprising the communication device as claimed in claim 22 and the communication device as claimed in claim 23.