WO2021128157A1

WO2021128157A1 - Handover method, device and system

Info

Publication number: WO2021128157A1
Application number: PCT/CN2019/128638
Authority: WO
Inventors: 朱方园; 李岩; 倪慧
Original assignee: 华为技术有限公司
Priority date: 2019-12-26
Filing date: 2019-12-26
Publication date: 2021-07-01

Abstract

Embodiments of the present application provide a handover method, device and system. The method comprises: a mobility management network element obtains information of at least one candidate base station; obtain network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station; determine a target base station from the at least one candidate base station according to the network slice information supported by the at least one candidate base station and a network slice associated with a current session of a terminal device, wherein the target base station supports the network slice associated with the current session of the terminal device; the mobility management network element sends a request message to the target base station, the request message being used for switching the terminal device from a source base station to the target base station. According to the method, in the handover scenario, service continuity for the terminal device can be maintained, thereby improving user experience.

Description

Switching method, equipment and system

Technical field

This application relates to the field of communication technology, and in particular to handover methods, devices and systems.

Background technique

A network slice is a logically isolated network used to support specific network capabilities and network characteristics. It can include the entire end-to-end (E2E) network, or part of the network functions can be in multiple network slices. Sharing is a key technology to meet the needs of the 5th generation (5G) mobile communication technology for network differentiation proposed by the 3rd generation partnership project (3GPP). Generally, the network characteristics of different network slices are not the same, and the network slices are required to be isolated from each other without affecting each other. For example, network slicing for augmented reality (AR) or virtual reality (VR) services requires large bandwidth and low latency; network slicing for Internet of Things (IOT) services requires massive terminal access. But the bandwidth is small and there is no requirement for delay.

When the terminal device is in the connected state, the movement of the terminal device will trigger the handover process of the base station. For example, the terminal device can be switched from the source base station to the target base station through the handover procedure of the NG interface. As shown in Figure 1, the source base station can select a target base station from multiple candidate base stations according to the measurement report reported by the terminal device. Then, the source base station can access and mobility management function of the current serving terminal device. , AMF) The network element sends a handover request message, and the handover request message carries the location information of the target base station. The AMF network element can determine the slice supported by the target base station after receiving the handover request message. If the target base station does not support the network slice associated with the current session of the terminal device, the current session of the terminal device cannot maintain session continuity on the target base station side, so the AMF network element will trigger the release of the current session of the terminal device. Therefore, using the above-mentioned "blind handover" switching method to switch the terminal device to the target base station may cause the current session of the terminal device to be interrupted, thereby interrupting the service currently used by the user, and reducing the user experience.

Summary of the invention

The embodiments of the present application provide handover methods, devices, and systems, which are used to maintain service continuity of terminal services in handover scenarios, thereby improving user experience.

In a first aspect, an embodiment of the present application provides a handover method, the method includes: a mobility management network element obtains information of at least one candidate base station; and obtains network slice information supported by at least one candidate base station according to the information of the at least one candidate base station; Determine a target base station from at least one candidate base station according to the network slice information supported by the at least one candidate base station and the network slice information associated with the current session of the terminal device, where the target base station supports the slice associated with the current session of the terminal device; mobility The management network element sends a request message to the target base station, where the request message is used to switch the terminal device from the source base station to the target base station. Using the handover method provided by the embodiments of the present application, since the mobility management network element considers the slices supported by each candidate base station and the network slices associated with the current session of the terminal device when determining the target base station, the determined target base station can support communication with the terminal device. The current session is associated with the slice. Therefore, in the scenario where the terminal device is switched from the source base station to the target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device service and improving user experience.

For example, the information of at least one candidate base station includes identification information of a tracking area (TA) where each candidate base station is located, or at least one item of identification information of each candidate base station. For example, the identification information of the tracking area where each candidate base station is located may be a tracking area identifier (TAI).

The at least one candidate base station here may be at least one candidate base station located in the service area of the mobility management network element.

In a possible design, the mobility management network element does not change during the handover. In this scenario, acquiring the information of at least one candidate base station by the mobility management network element includes: the mobility management network element receives the information of at least one candidate base station from the source base station.

In a possible design, the mobility management network element changes during the handover. The mobility management network element is the target mobility management network element after the change. Then, in this scenario, acquiring the information of at least one candidate base station by the mobility management network element includes: the target mobility management network element receives the information of at least one candidate base station from the source mobility management network element.

In a possible design, the mobility management network element obtains the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station, including: the mobility management network element determines that at least Network slice information supported by a candidate base station; wherein the association information includes a correspondence between the information of at least one candidate base station and the network slice information supported by the at least one candidate base station. For example, the mobility management network element may store the above-mentioned associated information in advance.

In a possible design, the mobility management network element obtains the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station, including: the mobility management network element determines the at least one candidate base station according to the information of the at least one candidate base station The slice supported by the tracking area where the base station is located.

In a second aspect, an embodiment of the present application provides a handover method, which includes: a source mobility management network element receives information of at least one candidate base station from a source base station; determining a target mobility management network element; The meta sends the information of at least one candidate base station and the information of the network slice associated with the current session of the terminal device. The information of the at least one candidate base station is used to determine the target base station, and the target base station supports the network slice associated with the current session of the terminal device. Using the handover method provided in the embodiments of the present application, the source mobility management network element determines the target mobility management network element, and sends the information of at least one candidate base station received from the source base station and the terminal equipment to the target mobility management network element. The information of the network slice associated with the current session enables the target mobility management network element to consider the slices supported by each candidate base station or its location and the network slices associated with the current session of the terminal device when determining the target base station, and the determined target base station can support and The current session of the terminal device is associated with the slice. Therefore, in the scenario where the terminal device is switched from the source base station to the target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device service and improving user experience.

In a possible design, the method further includes: the source mobility management network element determines that the source mobility management network element cannot continue to serve the terminal device. For example, when the source mobility management network element is not connected to at least one base station in the candidate base station, or when at least one of the candidate base stations connected to the source mobility management network element does not support the current session association with the terminal device The source mobility management network element determines that the source mobility management network element cannot continue to serve the terminal device.

In a possible design, the source mobility management network element determining the target mobility management network element includes: the source mobility management network element sends a request message to the first network element, and the request message is used to request the target mobility management network element Information. For example, the first network element includes a network storage function network element or a network slice selection function network element. For example, the source mobility management network element obtains the identification information of the tracking area where each candidate base station is located in at least one candidate base station; the above request message includes the identification information of the tracking area where each candidate base station is located in the at least one candidate base station.

In a possible design, when the first network element is a network storage function network element, the source mobility management network element determines the target mobility management network element, including: the source mobility management network element receives at least Identification information of a mobility management network element; determine the target mobility management network element. For example, the source mobility management network element determines from at least one mobility management network element that the first mobility management network element located in the same mobility management network element set as the source mobility management network element is the target mobility management network element . The way the source mobility management network element determines the target mobility management network element through the network storage function network element takes into account the compatibility of the existing process and is easy to implement.

Or, when the mobility management network element and the source mobility management network element in at least one mobility management network element are located in different mobility management network element sets, the source mobility management network element sends at least one candidate base station to the network slice selection function network element The identification information of the tracking area where each candidate base station is located and the information of the network slice associated with the current session of the terminal device; the information of the candidate target mobility management network element is received from the network slice selection function network element, and the mobility management network element of the candidate target is based on the candidate target mobility management network element. The information in determines the target mobility management network element, where the candidate target mobility management network element supports a network slice associated with the current session of the terminal device. This method takes into account the compatibility of existing processes and the accuracy and low latency of finding a suitable target mobility management network element.

In a possible design, when the first network element is a network slice selection function network element, the request message also includes network slice information associated with the current session of the terminal device, wherein the source mobility management network element determines the target mobility management The network element includes: the source mobility management network element receives the information of the candidate target mobility management network element from the network slice selection function network element, and determines the target mobility management network element according to the information of the candidate target mobility management network element, where the candidate The target mobility management network element supports network slicing associated with the current session of the terminal device. Since the network element with the network slice selection function senses the slices supported by each mobility management network element, and at the same time, it also senses the slices supported by the TA under each mobility management network element. Therefore, the candidate target mobility management determined by the network slice selection function network element The network element supports the slice associated with the current session of the UE, can accurately and quickly find the appropriate target mobility management network element, and shorten the handover delay.

In a possible design, the information of the candidate target mobility management network element includes the information of the set where the candidate target mobility management network element is located or the identification information of the candidate target mobility management network element.

In a possible design, the information of the at least one candidate base station includes identification information of the tracking area where the at least one candidate base station is located, or at least one item of identification information of the at least one candidate base station.

In a third aspect, an embodiment of the present application provides a handover method. The method includes: a source base station sends information of at least one candidate base station to a mobility management network element, the information of the at least one candidate base station is used to determine the target base station, and the target base station Support network slicing associated with the current session of the terminal device; receive a handover command, which is used to switch the terminal device from the source base station to the target base station. For example, the information of the at least one candidate base station includes identification information of the tracking area where the at least one candidate base station is located, or at least one item of identification information of the at least one candidate base station. Through the above method, the source base station sends the information of at least one candidate base station to the mobility management network element, so that the mobility management network element can consider each candidate base station or the slice supported by the location when determining the target base station, and the determined target base station can support and The current session of the terminal device is associated with the slice. Therefore, in the scenario where the terminal device is switched from the source base station to the target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device service and improving user experience.

In the fourth aspect, the embodiments of the present application provide a communication device for implementing the foregoing various methods. The communication device may be the mobility management network element in the first aspect described above, or a device including the mobility management network element described above; or, the communication device may be the source mobility management network element in the second aspect described above, or include The device for the source mobility management network element; the communication device may be the source base station in the third aspect, or a device including the source base station. The communication device includes a module, unit, or means corresponding to the foregoing method, and the module, unit, or means can be realized by hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the above-mentioned functions.

In a fifth aspect, an embodiment of the present application provides a communication device, including: a processor and a memory; the memory is used to store computer instructions, and when the processor executes the instructions, the communication device can execute any of the foregoing aspects. The method described. The communication device may be the mobility management network element in the first aspect described above, or a device including the mobility management network element described above; or, the communication device may be the source mobility management network element in the second aspect described above, or include The device for the source mobility management network element; the communication device may be the source base station in the third aspect, or a device including the source base station.

In a sixth aspect, a communication device is provided, including: a processor; the processor is configured to couple with a memory, and after reading an instruction in the memory, execute the method according to any of the foregoing aspects according to the instruction. The communication device may be the mobility management network element in the first aspect described above, or a device including the mobility management network element described above; or, the communication device may be the source mobility management network element in the second aspect described above, or include The device for the source mobility management network element; the communication device may be the source base station in the third aspect, or a device including the source base station.

In a seventh aspect, a computer-readable storage medium is provided. The computer-readable storage medium stores instructions that, when run on a computer, enable the computer to execute the method described in any of the above aspects.

In an eighth aspect, a computer program product containing instructions is provided, which when running on a computer, enables the computer to execute the method described in any of the above aspects.

In a ninth aspect, a communication device is provided (for example, the communication device may be a chip or a chip system), and the communication device includes a processor for implementing the functions involved in any of the foregoing aspects. In a possible design, the communication device further includes a memory for storing necessary program instructions and data. When the communication device is a chip system, it may be composed of a chip, or may include a chip and other discrete devices.

In a tenth aspect, a communication system is provided, and the communication system includes:

The source base station is used to send information about at least one candidate base station;

The mobility management network element is used to receive the information of at least one candidate base station from the source base station; obtain the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station; according to the network slice information supported by the at least one candidate base station and the terminal Information about the network slice associated with the current session of the device, determining the target base station from at least one candidate base station, where the target base station supports the network slice associated with the current session of the terminal device;

The target base station is used to receive a request message from the mobility management network element, and the request message is used to switch the terminal device from the source base station to the target base station.

In an eleventh aspect, a communication system is provided, and the communication system includes:

The source mobility management network element is used to receive the information of at least one candidate base station from the source base station; determine the target mobility management network element; send the information of at least one candidate base station and the information associated with the current session of the terminal device to the target mobility management network element Network slicing information;

The target mobility management network element is used to obtain network slice information supported by at least one candidate base station according to the information of at least one candidate base station; according to the network slice information supported by the at least one candidate base station and the information of the network slice associated with the current session of the terminal device, Determine a target base station from at least one candidate base station, where the target base station supports a network slice associated with the current session of the terminal device;

The target base station is used to receive a request message from the target mobility management network element, and the request message is used to switch the terminal device from the source base station to the target base station.

Among them, the technical effects brought about by any of the design methods in the fourth aspect to the eleventh aspect can be referred to the technical effects brought about by the different design methods in the first aspect, the second aspect, or the third aspect. Go into details again.

Description of the drawings

Figure 1 is a schematic diagram of a handover process in the prior art;

FIG. 2 is a schematic diagram of a 5G communication system provided by an embodiment of this application;

Figure 3 is a signaling interaction diagram of a handover method provided by an embodiment of the application;

FIG. 4 is a schematic diagram of a scenario in which the switching method of FIG. 3 is applied to an embodiment of the application;

Figure 5 is a signaling interaction diagram of a handover method provided by an embodiment of the application;

FIG. 6A is a schematic diagram of a scenario in which the switching method of FIG. 5 or FIG. 7 is applied to the embodiment of the application;

FIG. 6B is a schematic diagram of another scenario in which the switching method of FIG. 5 or FIG. 7 is applied to the embodiment of this application;

FIG. 7 is a signaling interaction diagram of a handover method provided by an embodiment of the application;

Figure 8 is a signaling interaction diagram of a handover method provided by an embodiment of the application;

FIG. 9 is a schematic diagram of a scenario in which the switching method of FIG. 8 is applied to an embodiment of the application;

FIG. 10 is a schematic flowchart of a handover method provided by an embodiment of this application;

FIG. 11 is a schematic flowchart of a handover method provided by an embodiment of this application;

FIG. 12 is a schematic flowchart of a handover method provided by an embodiment of this application;

FIG. 13 is a schematic structural diagram of an access and mobility management network element provided by an embodiment of this application;

FIG. 14 is a schematic structural diagram of a base station provided by an embodiment of the application;

FIG. 15 is a schematic structural diagram of a network device provided by an embodiment of this application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Wherein, in the description of this application, unless otherwise specified, "at least one of the following items" refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple. In addition, in order to facilitate a clear description of the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same or similar items with substantially the same function and effect. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and order of execution, and words such as "first" and "second" do not limit the difference. Meanwhile, in the embodiments of the present application, words such as "for example" are used as examples, illustrations, or illustrations. Any embodiment or design solution described as "for example" in the embodiments of the present application should not be construed as being more preferable or advantageous than other embodiments or design solutions. To be precise, the use of words such as "for example" is intended to present related concepts in a specific way to facilitate understanding.

In the 5G mobile network architecture, the core network includes control plane (control plane) network elements and user plane (user plane) network elements. Among them, the control plane network element is the third generation partnership project (third generation partnership project, 3GPP) traditional control network element mobility management entity (mobility management entity, MME) and serving gateway (serving gateway, SGW) control plane function , The control plane functions of the packet data network gateway (PGW) are merged into a unified control plane. The user plane function network element can realize the user plane functions of SGW and PGW (SGW-U and PGW-U). Further, the unified control plane network elements can be decomposed into access and mobility management function (AMF) network elements and session management function (session management function, SMF) network elements.

Fig. 2 shows a schematic diagram of a 5G communication system provided by an embodiment of the present application. The communication system at least includes access network (AN) equipment and mobility management network elements.

The base station in the embodiment of the present application, the base station 202 shown in FIG. 2 is a device that provides wireless communication functions for terminal devices. For example, base stations include but are not limited to: next-generation base stations (gnodeB, gNB) in 5G, evolved node B (evolved node B, eNB), radio network controller (RNC), node B (node B, NB), base station controller (BSC), base transceiver station (BTS), home base station (for example, home evolved nodeB, or home node B, HNB), baseband unit (BBU) , Transmission point (transmitting and receiving point, TRP), transmitting point (transmitting point, TP), mobile switching center. The base station may also be called an access network (access network, AN) device, for example, a radio access network (radio access network, RAN) device.

The mobility management network element in the embodiment of the present application is used for mobility management in a mobile network, such as location update of terminal equipment, network registration, handover, and so on. In a 5G communication system, the mobility management network element may be an access and mobility management function (AMF) network element 203, as shown in FIG. 2. In future communications, such as 6th generation (6G) communications, the mobility management network element may still be an AMF network element or have other names, which is not limited in the embodiment of the present application.

The communication system may also include a session management network element. The session management network element in the embodiment of the present application is used for session management in the mobile network, such as session establishment, modification, and release. Specific functions include allocating Internet Protocol (IP) addresses for terminal devices, selecting user plane network elements that provide message forwarding functions, and so on. In a 5G system, the session management network element may be a session management function (SMF) network element 204, as shown in FIG. 2. In future communications such as 6G, the session management network element may still be an SMF network element, or have other names, which are not limited in the embodiment of this application.

The communication system may also include a user plane function network element. The user plane network element in the embodiment of the present application is used to perform the forwarding of user data packets according to the routing rule of the session management network element. In a 5G communication system, the user management network element may be a user plane function (UPF) network element 205, as shown in FIG. 2. In future communications, such as 6G communications, the user plane network element may still be a UPF network element or have other names, which is not limited in the embodiment of the present application. The UPF network element 205 may be connected to a data network (DN) 206.

In addition, the communication system may also include terminal equipment. The terminal device in the embodiment of the present application, such as the terminal device 201 shown in FIG. 2, may be a device used to implement wireless communication functions. For example, it may be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; it may also be deployed On the water (such as ships, etc.); it can also be deployed in the air (such as airplanes, balloons, and satellites, etc.). Among them, the terminal equipment may be a user equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a mobile station in a 5G network or a public land mobile network (PLMN) that will evolve in the future. , Remote stations, remote terminals, mobile equipment, wireless communication equipment, terminal agents or terminal devices, etc. The access terminal can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), with wireless communication Functional handheld devices, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices or wearable devices, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, industrial control (industrial) Wireless terminal in control), wireless terminal in self-driving (self-driving), wireless terminal in remote medical (remote medical), wireless terminal in smart grid (smart grid), wireless terminal in transportation safety (transportation safety) Terminals, wireless terminals in smart cities, wireless terminals in smart homes, etc. The terminal equipment can be mobile or fixed.

Optionally, the communication system may further include at least one of a network storage function network element or a network slice selection function network element.

The network storage function network element in the embodiment of the present application is responsible for the registration and discovery functions of the network element. In addition, the network storage function network element can also maintain the information of the network element, such as the instance identifier of the network element, the type of the network element, the public land mobile network (PLMN) where the network element is located, and the At least one of the identifier of the slice supported by the network element, the IP address or the fully qualified domain name (FQDN) of the network element, the capabilities of the network element, or the services supported by the network element. In a 5G communication system, the network storage function network element may be a network storage function network element (Network Repository Function, NRF) network element 207, as shown in FIG. 2. In future communications such as 6G communications, the network storage function network element may still be an NRF network element or have other names, which is not limited in the embodiment of the present application.

The network slice selection function network element in the embodiment of the present application is used to select a network slice for a terminal device. In a 5G communication system, the network slice selection function network element may be a network slice selection function (NSSF) network element 208, as shown in FIG. 2. In future communications such as 6G communications, the network slice selection function network element may still be an NSSF network element or have other names, which is not limited in the embodiment of the present application.

The above-mentioned network elements can be realized by designated hardware, or by software examples on designated hardware, or by virtual functions instantiated on a suitable platform, and the present invention is not limited here. .

In the service-based architecture, a service-based interface is used in the control plane. For example, Namf is a service-based interface provided by AMF network elements, and AMF network elements can communicate with other network functions through Namf. Nsmf is a service-based interface provided by SMF. SMF can communicate with other network functions through Nsmf. Nnrf is a service-based interface provided by NRF network elements, and NRF network elements can communicate with other network functions through Nnrf. Nnssf is a service-based interface provided by NSSF network elements. NSSF network elements can communicate with other network functions through Nnssf. A functional network element can open its capabilities to other authorized functional network elements through a service-based interface, thereby providing network function (NF) services. In other words, NF service refers to the various capabilities that can be provided.

In addition, the embodiments of the present application may also be applicable to other future-oriented communication technologies. The network architecture and business scenarios described in this application are intended to explain the technical solutions of this application more clearly, and do not constitute a limitation on the technical solutions provided by this application. Those of ordinary skill in the art will know that with the evolution of the network architecture and new business scenarios The technical solutions provided in this application are equally applicable to similar technical problems.

This application is applicable to the layout of the network slice communication network. Network slicing is a logically isolated network used to support specific network capabilities and network characteristics. In the following description, network slices will be referred to simply as slices for description.

Figure 3 shows a signaling interaction diagram of the handover method provided according to an embodiment of the present application. Figure 3 relates to the interaction among UE, source base station, target base station, AMF, and SMF. For example, the UE may be the terminal device 201 in FIG. 2. The source base station or the target base station may be the RAN device 202 in FIG. 2. The AMF may be the AMF network element 203 in FIG. 2. The SMF may be the SMF network element 204 in FIG. 2. FIG. 3 will be described in conjunction with FIG. 4.

In this embodiment, the AMF does not change during the base station handover process. For example, if, among the candidate base stations to be handed over reported by the UE, at least one candidate base station is located in the service area of the current AMF, that is, the source base station before the UE handover and at least one candidate base station to be handed over by the UE are located in the same AMF. In the service area, and at least one candidate base station among the at least one candidate base station located in the service area of the current AMF supports the slice associated with the current session of the UE, it indicates that the current AMF can continue to serve the UE. In this scenario, according to the solution of the embodiment of the present application, the target base station can be determined by the AMF. In other words, it can be understood that among the candidate base stations to be handed over reported by the UE, there is a candidate base station located in the service area of the current AMF and supports slices associated with the current session of the UE. In this case, the AMF can choose This base station serves as the target base station. Since the source base station and the target base station are both located within the service range of the same AMF during the handover procedure, the current AMF can continue to serve the UE. As shown in Figure 3, the method includes the following steps:

Step 301: When the UE is in the connected state, the UE performs measurement according to the measurement configuration message issued by the source base station, and sends a measurement report to the source base station. The measurement report contains information about at least one candidate base station on the target side to be handed over.

The information of the candidate base stations on the target side to be handed over may be in the form of a list. For example, the information of the candidate base stations on the target side to be handed over includes a list of candidate target IDs and each candidate base station and UE. Between the measurement results. Measurement results include but are not limited to at least one of received signal strength indicator (RSSI), reference signal received power (RSRP), or reference signal received quality (RSRQ) .

For ease of description, the foregoing at least one candidate base station on the target side to be handed over may be referred to as a first candidate base station set.

Step 302: The source base station sends the first message to the AMF. The first message carries information of at least one candidate base station.

For example, the first message is a Handover Required (Handover Required) message.

The information of the at least one candidate base station may be the information of each candidate base station in the first candidate base station set.

For example, the information of at least one candidate base station may be in the form of a list. That is, the list includes the information of each candidate base station in at least one candidate base station. Optionally, the information of the at least one candidate base station includes at least one of identification information of a tracking area in which a candidate base station is located or identification information of a candidate base station. For example, the identification information of the tracking area where a candidate base station is located may be TAI. The identification information of a candidate base station may be a RAN node ID (RAN node ID).

For example, the list includes the information of four candidate base stations, and the four candidate base stations are respectively identified by Target ID-1, Target ID-2, Target ID-3, and Target ID-4, as shown in Table 1a. Among them, the list includes the identification (RAN node ID-1) of the candidate base station 1 corresponding to Target ID-1 and the identification TAI-1 of the TA where the candidate base station 1 is located, and the identification of the candidate base station 2 corresponding to the Target ID-2 (RAN node ID-1) RAN node ID-2) and the identification TAI-2 of the TA where the candidate base station 2 is located, the identification of the candidate base station 3 corresponding to Target ID-3 (RAN node ID-3) and the identification TAI- of the TA where the candidate base station 3 is located 3. The identification of the candidate base station 4 (RAN node ID-4) corresponding to the Target ID-4 and the identification TAI-4 of the TA where the candidate base station 4 is located.

第一候选基站集合的信息Information of the first candidate base station set
Target ID-1：RAN node ID-1+TAI-1Target ID-1: RAN node ID-1+TAI-1
Target ID-2：RAN node ID-2+TAI-2Target ID-2: RAN node ID-2+TAI-2
Target ID-3：RAN node ID-3+TAI-3Target ID-3: RAN node ID-3+TAI-3
Target ID-4：RAN node ID-4+TAI-4Target ID-4: RAN node ID-4+TAI-4

Table 1a

For another example, the list includes information about four candidate base stations, and the four candidate base stations are respectively identified by Target ID-1, Target ID-2, Target ID-3, and Target ID-4, as shown in Table 1b. Among them, the list includes the identification of candidate base station 1 corresponding to Target ID-1 (RAN node ID-1), the identification of candidate base station 2 corresponding to Target ID-2 (RAN node ID-2), and the identification corresponding to Target ID-3 The identification of the candidate base station 3 (RAN node ID-3), and the identification of the candidate base station 4 corresponding to the Target ID-4 (RAN node ID-4).

第一候选基站集合的信息Information of the first candidate base station set
Target ID-1：RAN node ID-1Target ID-1: RAN node ID-1
Target ID-2：RAN node ID-2Target ID-2: RAN node ID-2
Target ID-3：RAN node ID-3Target ID-3: RAN node ID-3
Target ID-4：RAN node ID-4Target ID-4: RAN node ID-4

Table 1b

For another example, the list includes information about four candidate base stations, and the four candidate base stations are respectively identified by Target ID-1, Target ID-2, Target ID-3, and Target ID-4, as shown in Table 1c. Among them, the list includes candidate base station 1 corresponding to Target ID-1, the identification TAI-1 of the TA where candidate base station 1 is located, and the identification TAI-2 of the TA where candidate base station 2 corresponding to Target ID-2 is located, and Target ID-3 corresponds to The identity of the TA where the candidate base station 3 is located is TAI-3, and the identity of the TA where the candidate base station 4 is located corresponding to Target ID-4 is TAI-4.

第一候选基站集合的信息Information of the first candidate base station set
Target ID-1：TAI-1Target ID-1: TAI-1
Target ID-2：TAI-2Target ID-2: TAI-2
Target ID-3：TAI-3Target ID-3: TAI-3
Target ID-4：TAI-4Target ID-4: TAI-4

Table 1c

Optionally, the handover request message may also include a source to target transparent container (Source to Target transparent container), an identifier of the current session of the UE, and session management information (session management information, SM info) corresponding to each session. For example, the session may be a packet data unit (PDU) session. The session management information may be N2 session management information (N2 session management information, N2 SM info).

Step 303: After receiving the information of the at least one candidate base station, the AMF obtains the network slice information supported by each candidate base station in the at least one candidate base station according to the information of the at least one candidate base station.

The following steps will be described below with reference to FIG. 4 and the above-mentioned Table 1a (or Table 1b, Table 1c) as an example. In the example in Figure 4, AMF supports three types of slices, slice 1, slice 2, and slice 3. The service area of the AMF includes TA1, TA2, and TA3. Among them, TA1 supports slice 1 and slice 2. TA2 supports slice 1, slice 2 and slice 3. TA3 supports slice 3. Among them, there are one or more base stations under each TA. TA1 supports slice 1 and slice 2, which means that each base station under TA1 supports slice 1 and slice 2, and so on. Therefore, it can be understood that the network slice information supported by a base station is equivalent to the network slice information supported by the TA where the base station is located.

For example, the AMF may first determine whether its service area contains at least one candidate base station (or the TA where the candidate base station is located). For example, the AMF may determine whether the AMF is connected to one of the at least one candidate base station according to the information of the candidate base station. In other words, the AMF determines whether there is at least one candidate base station connected to the AMF in the first candidate base station set, that is, whether there is at least one candidate base station located in the service area of the current AMF in the first candidate base station set. For example, the connection between the AMF and the base station may be an N2 interface connection. The presence of a connection between the AMF and a candidate base station indicates that the AMF and the candidate base station have performed the process of establishing an interface between the two.

For ease of description, the candidate base stations located in the service area of the current AMF in the first candidate base station set may be referred to as the second candidate base station set. The second candidate base station set may be a subset or a complete set of the first candidate base station set, and each candidate base station in the second candidate base station set is located in the service area of the AMF. The TA where each candidate base station in the second candidate base station set is located may be referred to as a candidate TA set. Optionally, the above collection can be implemented in the form of a list.

Through the above steps, the AMF determines the second set of candidate base stations connected to the AMF, or determines the set of candidate TAs. Taking Figure 4 and Table 1a as an example, the service area of AMF includes base station 1, base station 2, and base station 3, but does not include base station 4. Therefore, the second candidate base station set includes base station 1, base station 2, and base station 3. The candidate TA set includes TA1, TA2 and TA3.

Optionally, the AMF also obtains information about each candidate base station in the second candidate base station set, as shown in Table 2. For example, base station 1 in the second candidate base station set is located at TA1 with the identification TAI-1, base station 2 is located at TA2 with the identification TAI-2, and base station 3 is located at TA3 with the identification TAI-3.

第二候选基站集合的信息Information of the second candidate base station set
Target ID-1：RAN node ID-1+TAI-1Target ID-1: RAN node ID-1+TAI-1
Target ID-2：RAN node ID-2+TAI-2Target ID-2: RAN node ID-2+TAI-2
Target ID-3：RAN node ID-3+TAI-3Target ID-3: RAN node ID-3+TAI-3

Table 2

Then, the AMF may determine the network slice information supported by each candidate base station in the second candidate base station set.

For example, in the process of establishing an interface between the AMF and the base station, the AMF and the base station negotiate the slicing capabilities, that is, exchange the slices supported by each. For example, the base station sends an interface establishment request message to the AMF, and the interface establishment request message carries a slice supported by the TA where the base station is located. If the base station has interfaces with multiple AMFs, the base station sends the aforementioned interface establishment request messages to the multiple AMFs respectively. After the AMF receives the interface establishment request message sent by the base station, it returns an interface establishment response message to the base station, and the interface establishment response message carries the slice supported by the AMF. Through the aforementioned interaction process, the AMF can learn the slices supported by the TA where the base station connected to it is located, and at the same time, the base station can also learn the slices supported by the AMF connected to it. Therefore, after the AMF and the base station perform the interface establishment process, the AMF locally stores the slices supported by each TA in the AMF service area. Combined with the example in Figure 4, the information stored locally in the AMF is shown in Table 3. The first line indicates that TA1 (or a base station located under TA1) identified as TAI-1 supports slice 1 and slice 2, and the second line indicates that TA2 (or a base station located under TA2) identified as TAI-2 supports slice 1, slice 2 and slice 3, the third row indicates that TA3 (or a base station located under TA3), which is identified as TAI-3, supports slice 3.

TAI-1：切片1，切片2TAI-1: slice 1, slice 2
TAI-2：切片1，切片2，切片3TAI-2: slice 1, slice 2, slice 3
TAI-3：切片3TAI-3: Slice 3

table 3

Optionally, the AMF may obtain network slice information supported by each candidate base station in the second candidate base station set according to the slices supported by each TA in the service area. For example, the AMF can learn that base station 1 at TA1 supports slice 1 and slice 2, base station 2 at TA2 supports slice 1, slice 2 and slice 3, and base station 3 at TA3 supports slice 3. Thus, the AMF determines the network slice information of each candidate base station in the second candidate base station set.

Step 304: The AMF determines a target base station from the at least one candidate base station according to the network slice information supported by each candidate base station in the at least one candidate base station and the slice information associated with the current session of the UE.

For example, the AMF determines the slice associated with the current session of the UE according to the UE context, and determines the target base station from at least one candidate base station. The determined target base station supports the slice associated with the current session of the UE.

For example, the AMF learns that the UE currently has three sessions established according to the UE context. Among them, session 1 is associated with slice 1, session 2 is associated with slice 2, and session 3 is associated with slice 3, and all three sessions need to meet session continuity. Since base station 2 supports slice 1, slice 2 and slice 3, base station 2 can satisfy the service continuity of the current session of the UE. Therefore, the AMF determines that base station 2 is the target base station.

For another example, the AMF learns that the UE currently has two sessions established according to the UE context, where session 1 is associated with slice 1, and session 2 is associated with slice 2, and both sessions need to meet session continuity. Since base station 1 (or TA1 where base station 1 is located) and base station 2 (or TA2 where base station 2 is located) both support slice 1 and slice 2, base station 1 (or TA1 where base station 1 is located) and base station 2 (or base station 2 are located) TA2) can satisfy the service continuity of the current session of the UE. At this time, the AMF can determine the target base station from the base station 1 and the base station 2 according to other conditions. Optionally, other conditions may include measurement results between the base station and the UE. For example, the AMF may obtain the measurement result between the base station 1 and the UE and the measurement result between the base station 2 and the UE from the source base station, and the AMF determines that the base station with a relatively higher measurement result is the target base station.

It should be noted that, for a session that does not need to meet session continuity, when the AMF selects a target base station, the slice associated with the session may not be considered.

In addition, this embodiment also provides another implementation manner to replace the foregoing steps 303 and 304.

For example, the AMF first determines at least one candidate TA according to the slices supported by each TA in the AMF service area and the slices associated with the current session of the UE. Each TA in at least one candidate TA supports a slice associated with the current session of the UE.

For example, the slices supported by each TA in the AMF service area can refer to the description in Table 3 above.

For example, the AMF learns that the UE currently has three sessions established according to the UE context. Among them, session 1 is associated with slice 1, session 2 is associated with slice 2, and session 3 is associated with slice 3, and all three sessions need to meet session continuity. Therefore, the AMF determines that TA2 identified as TAI-2 is a candidate TA.

For another example, the AMF learns that the UE currently has two sessions established according to the UE context, where session 1 is associated with slice 1, and session 2 is associated with slice 2, and both sessions need to meet session continuity. Therefore, the AMF determines TA1 identified as TAI-1 and TA2 identified as TAI-2 as candidate TAs.

Then, the AMF determines the target base station from the candidate base stations corresponding to the at least one candidate TA according to the information of the first candidate base station set and the at least one candidate TA.

For example, if the information of the first candidate base station set includes at least one candidate TA, the AMF may determine the target base station from the candidate base stations corresponding to the at least one candidate TA. In the first example in which the AMF determines that TA2 with the identification TAI-2 is a candidate TA, because the information of the first candidate base station set includes TAI-2, the AMF can determine that the base station 2 located at TA2 is the target base station. In the second example where AMF determines that TA1 with TAI-1 and TA2 with TAI-2 are candidate TAs, because the information of the first candidate base station set includes TAI-1 and TAI-2, AMF can start from In the base station 1 of TA1 and the base station 2 located in TA2, the target base station is determined.

If at least one candidate TA also includes TAs of candidate base stations that are not included in the first candidate base station set, AMF can take the intersection of the first candidate base station set and the candidate base stations under at least one candidate TA, and then determine in the intersection set Target base station.

Similarly, the AMF may also combine other conditions to determine the target base station from the candidate base stations corresponding to at least one candidate TA.

Regardless of the foregoing implementation manner, the target base station determined by the AMF supports the slice associated with the current session.

Through the above steps, AMF determines the target base station. For example, the AMF can determine the information of the target base station. The information of the target base station includes at least one of the TAI of the TA where the target base station is located, or the RAN node ID of the target base station.

In step 305, each network element interacts to continue to execute the steps of the handover process.

For example, the AMF determines the identity of the SMF according to the correspondence between the PDU session and the SMF stored in the UE context, and further invokes the servicing operation of the SMF, for example, the servicing operation of updating the SM context (Nsmf_PDUSession_UpdateSMContext), and sends a request message. The message includes the PDU session identifier, the location information of the target base station, the AMF identifier and N2 SM information. The N2 SM information includes the list of PDU Sessions To Be Switched from the source base station to the target base station. The SMF sends the PDU session identifier and N2 SM information to the AMF through the response of the servicing operation. The N2 SM information in the response includes at least one of the address of the UPF, tunnel information of the UPF, and quality of service (QoS). If the UE has established multiple PDU sessions and multiple PDU sessions correspond to multiple SMFs, then the AMF calls the servicing operations of multiple SMFs respectively, and each SMF of the multiple SMFs sends the PDU session identifier to the AMF through the response of the servicing operation And N2 SM information.

Step 306: The AMF sends a handover request (handover request) message to the target base station.

Optionally, the handover request message carries allowed network slice selection assistance information (allowed network slice selection assistance information, allowed NSSAI) determined by the AMF and N2 SM information received from each SMF.

It should be noted that the above steps may be operations involved in the handover preparation phase, and the handover execution phase is entered after the above steps are executed. In the handover execution phase, the AMF can deliver the information required for the handover execution to the source base station, which is not described in detail in this article.

In the prior art, the source base station selects a target base station from multiple candidate base stations according to the measurement report reported by the terminal device. Since the source base station does not perceive the slices supported by the candidate base station on the target side to be handed over, a situation may arise that the determined target base station does not support the slices associated with the current session of the UE. Then, after the AMF receives the handover request message sent by the source base station, it will trigger the release of the current session of the UE. Therefore, the current session of the UE cannot maintain session continuity at the target base station. However, according to the above solutions of the embodiments of the present application, since the AMF considers the slices supported by each candidate base station and the slices associated with the current session of the UE when determining the target base station, the determined target base station can support the slices associated with the current session of the UE. Therefore, in the scenario where the terminal device is switched from the source base station to the target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device's business and improving user experience.

Fig. 5 is a signaling interaction diagram of the handover method provided according to an embodiment of the present application. Figure 5 relates to the interaction among UE, source base station, target base station, AMF, SMF, and NRF. For example, the UE may be the terminal device 201 in FIG. 2. The source base station or the target base station may be the RAN device 202 in FIG. 2. The AMF may be the AMF network element 203 in FIG. 2. The SMF may be the SMF network element 204 in FIG. 2. The NRF may be the NRF network element 207 in FIG. 2. Fig. 5 will be described in conjunction with Fig. 6A and Fig. 6B.

In this embodiment, the AMF changes during the base station handover process. If, among the candidate base stations to be handed over reported by the UE, any candidate base station is not located in the current AMF service area, or, among the candidate base stations to be handed over reported by the UE, any candidate base station located in the current AMF service area If the slice associated with the current session of the UE is not supported, it means that the current AMF cannot continue to serve the UE. In this scenario, AMF handover (AMF reallocation) will be triggered. According to the solution of the embodiment of the present application, the source AMF may determine the target AMF through NRF, and then the target AMF may determine the target base station.

As shown in Figure 5, the method includes the following steps:

Step 501: When the UE is in the connected state, the UE performs measurement according to the measurement configuration message issued by the source base station, and sends a measurement report to the source base station. The measurement report contains at least one candidate base station information of the target side to be handed over.

Step 502: The source base station sends a first message to the source AMF. The first message carries information of at least one candidate base station.

For steps 501 and 502, reference may be made to the description of steps 301 and 302 in FIG. 4, which will not be repeated here.

Step 503: The source AMF judges that the source AMF cannot continue to serve the UE.

For example, among the candidate base stations to be handed over reported by the UE, if none of the candidate base stations is located in the service area of the source AMF, the source AMF cannot continue to serve the UE. Take FIG. 6A and the above-mentioned Table 1a as an example for description. As shown in Table 1a above, the information of at least one candidate base station includes the identification RAN node ID-1 of the candidate base station 1 corresponding to Target ID-1 and the identification TAI-1 of the TA where the candidate base station 1 is located, and the candidate corresponding to Target ID-2 The identification RAN node ID-2 of the base station 2 and the identification TAI-2 of the TA where the candidate base station 2 is located, the identification RAN node ID-3 of the candidate base station 3 corresponding to the Target ID-3 and the identification TAI of the TA where the candidate base station 3 is located -3, the identification RAN node ID-4 of the candidate base station 4 corresponding to the Target ID-4 and the identification TAI-4 of the TA where the candidate base station 4 is located. In the example of FIG. 6A, the service area of the source AMF includes TA5. Therefore, if at least one

candidate base station

1, 2, 3, 4 to be handed over is not in the service area of the source AMF, the source AMF cannot continue to serve the UE. In addition, when there is no interface connection between the source AMF and the candidate base station, the source AMF can directly the source AMF cannot continue to serve the UE.

Or, among the candidate base stations to be handed over reported by the UE, none of the candidate base stations located in the service area of the source AMF supports the slice associated with the current session of the UE, and the source AMF cannot continue to serve the UE. Optionally, the source AMF may first determine the slice supported by the candidate base station located in the service area of the source AMF, and then determine whether the candidate base station located in the service area of the source AMF can support the slice associated with the current session of the UE. This can refer to the description of steps 303 and 304 in FIG. 3. Take Figure 6B and Table 1a as an example for description. In the example of FIG. 6B, the service area of the source AMF includes TA1, and TA1 supports slice 4. Therefore, among at least one

candidate base station

1, 2, 3, 4 to be handed over, the base station 1 under TA1 is located in the service area of the source AMF, and the base station 1 supports slice 4. However, if the UE currently establishes two sessions, where session 1 is associated with slice 1, session 2 is associated with slice 2, and both sessions need to meet session continuity. Therefore, the base station 1 located in the service area of the source AMF cannot support the slice associated with the current session of the UE, and the source AMF cannot continue to serve the UE.

In step 504, the source AMF invokes the servicing operation of the NRF, for example, discovering the servicing operation of the network element (Nnrf_NFDiscovery), and sends a request message a (for example, Nnrf_NFDiscovery_Request), which is used to request information of the target AMF.

For example, the request message a carries identification information of the tracking area of each candidate base station in the first candidate base station set, for example, TAI. For example, the source AMF determines the TAI of each candidate base station in the first candidate base station set according to the information of the first candidate base station set. For example, in conjunction with Table 1a, the TAI of each candidate base station in the first candidate base station set determined by the source AMF includes TAI-1, TAI-2, TAI-3, and TAI-4.

Optionally, the request message a also carries single network slice selection assistance information (S-NSSAI) of the slice associated with the current session of the UE. For example, the S-NSSAI(s) of the slice associated with the current session of the UE may be represented by S-NSSAI(s) of PDU session(s).

Optionally, the request message a also carries at least one of the identification of the AMF set where the source AMF is located (source AMF set ID) and the identification of the region where the source AMF is located (source AMF region ID).

Step 505: After receiving the request message a, the NRF determines the information of the target AMF, and returns the information of at least one target AMF to the source AMF.

Optionally, the information of the at least one target AMF may be the globally unique AMF identifier (GUAMI) of the at least one target AMF. GUAMI is used to identify an AMF. The composition of GUAMI is:

Among them, MCC stands for Mobile Country Code. MCC resources are uniformly allocated and managed by the ITU organization to uniquely identify the country to which a mobile user belongs, with a total of 3 digits, for example, 460 for China. MNC stands for Mobile Network Code, a total of 2 digits. The AMF region ID is the identifier of the region where the AMF is located. The AMF set ID is the identifier of the AMF set where the AMF is located. The AMF pointer is used to point to an AMF in the AMF set.

For example, the NRF determines the target AMF according to the TAI in the request message a. Generally speaking, the target AMF determined by the NRF satisfies: the service area of the target AMF includes the TA corresponding to the TAI.

Optionally, if the request message includes multiple TAIs, the NRF determines the target AMF information for each TA. The information of the target AMF determined for each TA may be in the form of a GUAMI list, and the GUAMI list includes at least one GUAMI. As described above, the TAI of the candidate base station includes TAI-1, TAI-2, TAI-3, and TAI-4. Then, the information of the target AMF determined by the NRF can be as shown in Table 4.

Table 4

Among them, the AMF involved in GUAMI list 1 can serve candidate base stations located in TA1 corresponding to TAI-1. The AMF involved in GUAMI list 2 can serve candidate base stations located in TA2 corresponding to TAI-2. The AMF involved in GUAMI list 3 can serve candidate base stations located in TAI-3 corresponding to TA3. The AMF involved in GUAMI list 4 can serve candidate base stations located in TAI-4 corresponding to TA4.

Optionally, the NRF may further consider at least one of the source AMF set ID and the source AMF region ID when determining the target AMF. In this way, the target AMF determined by the NRF also satisfies: it is located in the same area as the source AMF, and located in the same AMF set as the source AMF, at least one of the two.

After the NRF determines the information of the target AMF, it may return at least one target AMF information to the source AMF through a response message (for example, Nnrf_NFDiscovery_Response).

In step 506, the source AMF determines the target AMF from the at least one target AMF according to the information of the at least one target AMF received in step 505.

For example, the information of the at least one target AMF is the GUAMI of the at least one target AMF. The source AMF may determine the AMF set ID and the AMF region ID of the AMF from the GUAMI of at least one target AMF. Then, optionally, the source AMF determines the AMFs located in the same area and the same AMF set as the source AMF, and then selects the target AMF within this range. That is, the determined target AMF and the source AMF are located in the same area and in the same AMF set. Generally speaking, different AMF sets may support different slices. Therefore, the target AMF located in the same AMF set as the source AMF must be able to support the slice associated with the current session of the UE.

Optionally, when the source AMF set ID and source AMF region ID are carried in the request message in step 504, and the NRF determines that the target AMF considers the source AMF set ID and source AMF region ID, the target AMF returned by the NRF in step 505 has been satisfied Note: The target AMF and the source AMF are located in the same area and in the same AMF set. Therefore, in step 506, the source AMF can directly select the target AMF according to the information of the target AMF.

In step 507, the source AMF invokes the servicing operation of the target AMF, for example, the servicing operation of creating a UE context (Namf_Communication_CreateUEContext), and sends a request message b (for example, Namf_Communication_CreateUEContext Request). The request message b carries the source AMF and is received in step 502. Information of at least one candidate base station set. Optionally, the request message b further includes a transparent container from the source to the target, the identifier of the current session of the UE, and session management information corresponding to each session.

Step 508: After receiving the information of the at least one candidate base station, the target AMF obtains the network slice information supported by each candidate base station in the at least one candidate base station according to the information of the at least one candidate base station.

Step 509: The target AMF determines the target base station from the at least one candidate base station according to the network slice information supported by each candidate base station in the at least one candidate base station and the slice information associated with the current session of the UE.

For how the target AMF determines the target base station from at least one candidate base station, refer to the description of how the AMF determines the target base station from at least one candidate base station in steps 303 and 304 in FIG. 3, which will not be repeated here.

For example, in conjunction with the example in Figure 6A or Figure 6B, if the UE currently has three sessions established, among which session 1 is associated with slice 1, session 2 is associated with slice 2, and session 3 is associated with slice 3, and all three sessions need to meet Session continuity. Since base station 2 (or TA2 where base station 2 is located) supports slice 1, slice 2 and slice 3, base station 2 (or TA2 where base station 2 is located) can meet the service continuity of the current session of the UE. Therefore, the target AMF determines that base station 2 is the target base station.

Step 510, each network element interacts to continue to perform the steps of the handover process.

For the operation of the target AMF, please refer to the operation of the AMF in step 305 in FIG. 3, which will not be repeated here.

Step 511: The target AMF sends a handover request (handover request) message to the target base station.

Optionally, the handover request message carries the target AMF determined allowed NSSAI and N2 SM information received from each SMF.

According to the above solution of the embodiment of the present application, in the case that the source AMF cannot continue to serve the UE, the source AMF determines the target AMF through the NRF and sends the received information of at least one candidate base station to the target AMF. Since the target AMF considers the slices supported by each candidate base station or its location and the slices associated with the current session of the UE when determining the target base station, the determined target base station can support the slices associated with the current session of the UE. In the scenario where the source base station is switched to the target base station, the current session will not be interrupted, thereby maintaining service continuity for the service of the terminal device and improving user experience.

In addition, in this embodiment, the way in which the source AMF determines the target AMF through the NRF takes into account the compatibility of the existing process, which is easy to implement.

Fig. 7 shows a signaling interaction diagram of a handover method provided according to an embodiment of the present application. Figure 7 relates to the interaction among UE, source base station, target base station, AMF, SMF, and NSSF. For example, the UE may be the terminal device 201 in FIG. 2. The source base station or the target base station may be the RAN device 202 in FIG. 2. The AMF may be the AMF network element 203 in FIG. 2. The SMF may be the SMF network element 204 in FIG. 2. The NSSF may be the NSSF network element 208 in FIG. 2. FIG. 7 will be described in conjunction with FIG. 3 and FIG. 5.

Similarly, in this embodiment, the AMF changes during the base station handover process. If, among the candidate base stations to be handed over reported by the UE, any candidate base station is not located in the current AMF service area, or, among the candidate base stations to be handed over reported by the UE, any candidate base station located in the current AMF service area If the slice associated with the current session of the UE is not supported, it means that the current AMF cannot continue to serve the UE. In this scenario, AMF switching will be triggered. According to the solution of the embodiment of the present application, the source AMF may determine the target AMF through the NSSF, and then the target AMF may determine the target base station.

As shown in Figure 7, the method includes the following steps:

Step 701: When the UE is in the connected state, the UE performs measurement according to the measurement configuration message issued by the source base station, and sends a measurement report to the source base station. The measurement report contains at least one candidate base station information of the target side to be handed over.

Step 702: The source base station sends a first message to the source AMF. The first message carries information of at least one candidate base station.

For steps 701 and 702, reference may be made to the description of steps 301 and 302 in FIG. 3, which will not be repeated here.

Step 703: The source AMF judges that the AMF cannot continue to serve the UE.

For step 703, reference may be made to the description of step 503 in FIG. 5, which will not be repeated here.

In step 704, the source AMF invokes the servicing operation of the NSSF, for example, the servicing operation of network slice selection (Nnssf_NSSelection_Get), and sends a request message c, which is used to request information of the target AMF.

For example, the request message c carries the identification information of the tracking area of each candidate base station in the first candidate base station set and the single network slice selection assistance information (single network slice selection assistance information, S-NSSAI) of the slice associated with the current session of the UE. . For example, the S-NSSAI(s) of the slice associated with the current session of the UE may be represented by S-NSSAI(s) of PDU session(s). For example, if the UE currently has three sessions established, session 1 is associated with slice 1, session 2 is associated with slice 2, and session 3 is associated with slice 3, and all three sessions need to meet session continuity. Therefore, the S-NSSAI of the slice associated with the current session of the UE includes the S-NSSAI1 of the slice 1, the S-NSSAI2 of the slice 2, and the S-NSSAI3 of the slice 3. Optionally, the identification information of the tracking area of the candidate base station includes the TAI of the candidate base station. For example, the source AMF determines the TAI of each candidate base station in the first candidate base station set according to the information of the first candidate base station set.

Step 705: After receiving the request message, the NSSF determines the information of the candidate target AMF, and returns the information of the candidate target AMF to the source AMF.

Since NSSF perceives the slices supported by each AMF, and at the same time, NSSF also perceives the slices supported by TA under each AMF, the NSSF can use the TA information of each candidate base station in the first candidate base station set and the S-NSSAI of the slice associated with the current session of the UE. (s) Determine the information of the candidate target AMF that supports the slice associated with the current session of the UE. That is, the candidate target AMF determined by the NSSF can support the slice associated with the current session of the UE. With reference to the example of FIG. 6A or 6B, since the target AMF covers TAI2, and TAI2 supports slice 1, slice 2, and slice 3, the NSSF determines that the target AMF is a candidate target AMF.

For example, the information of the candidate target AMF may include information of the set where the candidate target AMF is located or identification information (such as GUAMI) of at least one candidate target AMF. Optionally, the information of the candidate target AMF may also include the TAI of the TA where the candidate target AMF is located.

After the NSSF determines the information of the candidate target AMF, it can return the information of the candidate target AMF to the source AMF through a response message (for example, Nnssf_NSSelection_Get response).

In step 706, the source AMF selects the target AMF according to the information of the candidate target AMF received in step 705.

For example, when the information of the candidate target AMF is the information of the set where the candidate target AMF is located, the source AMF first determines the target AMF set. Optionally, the source AMF preferentially selects the AMF set where the source AMF is located as the target AMF set. Then, the source AMF may invoke the servicing operation of the NRF to determine the GUAMI of at least one target AMF in the target AMF set, and determine one GUAMI from the at least one GUAMI. The AMF identified by the GUAMI is the final target AMF.

Alternatively, when the information of the candidate target AMF is the GUAMI of at least one candidate target AMF, the source AMF may determine one GUAMI from the at least one GUAMI. The AMF identified by the GUAMI is the final target AMF.

Step 707: The source AMF invokes the servicing operation of the target AMF, for example, creating a UE context servicing operation (Namf_Communication_CreateUEContext), and sending a request message d (Namf_Communication_CreateUEContext Request). The request message d carries at least the information received by the source AMF in step 702. Information about a set of candidate base stations.

Step 708: After receiving the information of the at least one candidate base station, the target AMF obtains the network slice information supported by each candidate base station in the at least one candidate base station according to the information of the at least one candidate base station.

Step 709: The target AMF determines the target base station from the at least one candidate base station according to the network slice information supported by each candidate base station in the at least one candidate base station and the slice information associated with the current session of the UE.

Step 710, each network element interacts to continue to execute the steps of the handover process.

Step 711: The target AMF sends a handover request (handover request) message to the target base station.

For steps 707 to 711, reference may be made to the description of steps 507-511 in FIG. 5, which will not be repeated here.

According to the above solution of the embodiment of the present application, in the case that the source AMF cannot continue to serve the UE, the source AMF determines the target AMF through the NSSF and sends the received information of at least one candidate base station to the target AMF. Since the target AMF considers the slices supported by each candidate base station or its location and the slices associated with the current session of the UE when determining the target base station, the determined target base station can support the slices associated with the current session of the UE. In the scenario where the source base station is switched to the target base station, the current session will not be interrupted, thereby maintaining service continuity for the service of the terminal device and improving the user experience.

In addition, in this embodiment, the source AMF determines the target AMF through the NSSF. Since the NSSF senses the slices supported by each AMF, and at the same time, the NSSF also senses the slices supported by the TA under each AMF. Therefore, the candidate target AMF determined by the NSSF supports and The slice associated with the current session of the UE can accurately and quickly find a suitable target AMF, which reduces the handover delay.

Fig. 8 is a signaling interaction diagram of the handover method provided according to an embodiment of the present application. Figure 8 relates to the interaction among UE, source base station, target base station, AMF, SMF, NRF, and NSSF. For example, the UE may be the terminal device 201 in FIG. 2. The source base station or the target base station may be the RAN device 202 in FIG. 2. The AMF may be the AMF network element 203 in FIG. 2. The SMF may be the SMF network element 204 in FIG. 2. The NRF may be the NRF network element 207 in FIG. 2. The NSSF may be the NSSF network element 208 in FIG. 2. Fig. 8 will be described in conjunction with Fig. 3, Fig. 5, Fig. 7 and Fig. 9.

Similar to FIG. 5, in this embodiment, the AMF changes during the base station handover process. The difference between the method in FIG. 8 and the method in FIG. 5 is that after the method shown in FIG. 8 determines that the source AMF cannot continue to serve the UE, the source AMF first selects the target AMF through the NRF. However, the source AMF cannot determine the target AMF based on the information returned by the NRF. Therefore, the source AMF further uses NSSF to determine the target AMF.

As shown in Figure 8, the method includes the following steps:

Step 801: When the UE is in the connected state, the UE performs measurement according to the measurement configuration message issued by the source base station, and sends a measurement report to the source base station. The measurement report contains at least one candidate base station information of the target side to be handed over.

Step 802: The source base station sends a first message to the source AMF. The first message carries information of at least one candidate base station.

For steps 801 and 802, reference may be made to the description of steps 301 and 302 in FIG. 3, which will not be repeated here.

Step 803: The source AMF judges that the source AMF cannot continue to serve the UE.

In step 804, the source AMF invokes the servicing operation of the NRF, for example, discovering the servicing operation of the network element (Nnrf_NFDiscovery), and sends a request message e (for example, Nnrf_NFDiscovery_Request), which is used to request information of the target AMF.

Step 805: After receiving the request message e, the NRF determines the information of the target AMF, and returns the information of the target AMF to the source AMF.

For steps 803 to 805, reference may be made to the description of steps 503 to 505 in FIG. 5, which will not be repeated here.

In step 806, the source AMF cannot determine the target AMF based on the information returned by the NRF.

Optionally, when the target AMF returned by the NRF and the source AMF are not in the same AMF set, the source AMF cannot determine the target AMF based on the information returned by the NRF. Optionally, there are two cases here: one is that the NRF returns information about a target AMF, and the target AMF and the source AMF are not in the same AMF set; the other is that the NRF returns information about multiple target AMFs, and more Any one of the target AMFs and the source AMF are not in the same AMF set. Optionally, in the second case, multiple target AMFs may be located in different AMF sets or in different regions.

For example, the source AMF determines at least one item in the set or area where the at least one target AMF is located according to the GUAMI of at least one target AMF returned by the NRF.

When at least one item in the set or area of the target AMF is different from the source AMF, the source AMF cannot determine the target AMF based on the information returned by the NRF.

This will be described in conjunction with FIG. 9. In the example in Figure 9, NRF determines the target AMF 1 and target AMF 2 as the target AMF according to the TAI of at least one candidate base station sent by the source AMF, namely TAI-1, TAI-2, TAI-3, and TAI-4. , The service area of the target AMF 1 includes TAI-1 and TAI-2, and the service area of the target AMF 2 includes TAI-3. And TA1 supports slice 1 and slice 2. TA2 supports slice 1, slice 2 and slice 3. TA3 supports slice 3. When the source AMF obtains the GUAMI of AMF 1 and the GUAMI of AMF 2 from the NRF, it is determined from the GUAMI of AMF 1 and the GUAMI of AMF 2 that neither the target AMF 1 nor the target AMF 2 is located in the AMF collection or area where the source AMF is located, and the target The AMF 1 and the target AMF 2 are located in different AMF sets or in different areas, so the source AMF cannot determine the target AMF from the target AMF 1 and the target AMF 2.

In step 807, the source AMF invokes the servicing operation of the NSSF, for example, the servicing operation of network slice selection (Nnssf_NSSelection_Get), and sends a request message f, which is used to request information of the target AMF.

Step 808: After receiving the request message f, the NSSF determines the information of the candidate target AMF, and returns the information of the candidate target AMF to the source AMF.

In step 809, the source AMF selects the target AMF according to the information of the candidate target AMF received in step 808.

For steps 807 to 809, refer to the description of steps 704 to 706 in FIG. 7.

For example, with reference to the example in FIG. 9, the TAI of the candidate base station received by the NSSF from the source AMF includes TAI1, TAI2, TAI3, and TAI4. If the UE currently has three sessions established, among which session 1 is associated with slice 1, session 2 is associated with slice 2, and session 3 is associated with slice 3, and all three sessions need to meet session continuity. Therefore, the S-NSSAI of the slice associated with the current session of the UE includes the S-NSSAI1 of the slice 1, the S-NSSAI2 of the slice 2, and the S-NSSAI3 of the slice 3. Since the NSSF senses the TAI supported by each AMF and the network slices supported by the TA under each AMF, since the target AMF1 in Figure 9 covers TAI2, and TAI2 supports slice 1, slice 2 and slice 3, NSSF determines the target AMF1 as a candidate Target AMF, return information about target AMF1. The source AMF determines the target AMF 1 as the target AMF according to the received information of the target AMF1.

Step 810: The source AMF invokes the servicing operation of the target AMF (such as the target AMF 1), for example, the servicing operation of creating a UE context (Namf_Communication_CreateUEContext), and sends a request message g (for example, Namf_Communication_CreateUEContext Request), and the request message g carries the source The information of at least one candidate base station set received by the AMF in step 802.

Step 811: After receiving the information of the at least one candidate base station, the target AMF obtains the network slice information supported by each candidate base station in the at least one candidate base station according to the information of the at least one candidate base station.

Step 812: The target AMF determines the target base station from the at least one candidate base station according to the network slice information supported by each candidate base station in the at least one candidate base station and the slice information associated with the current session of the UE.

Step 813, each network element interacts to continue to perform the steps of the handover procedure.

Step 814: The target AMF sends a handover request (handover request) message to the target base station.

For steps 810 to 814, reference may be made to the description of steps 507-511 in FIG. 5, which will not be repeated here.

For example, in conjunction with the example in Figure 9, if the UE currently has three sessions, among which session 1 is associated with slice 1, session 2 is associated with slice 2, and session 3 is associated with slice 3, and all three sessions need to meet session continuity. . Since base station 2 (or TA2 where base station 2 is located) supports slice 1, slice 2 and slice 3, base station 2 (or TA2 where base station 2 is located) can meet the service continuity of the current session of the UE. Therefore, the target AMF1 determines that the base station 2 is the target base station.

That is to say, the difference between FIG. 7 and FIG. 8 is that in the example of FIG. 7, the source AMF directly determines the target AMF through the NSSF. In the example of FIG. 8, the source AMF first expects to determine the target AMF through the NRF, and only determines the target AMF through the NSSF when the target AMF cannot be determined based on the information returned by the NRF. This method takes into account the compatibility of the existing process and the accuracy and low latency of finding a suitable target AMF.

With reference to the description of FIG. 3 to FIG. 9, as shown in FIG. 10, the present application provides a handover method. This method is executed by the mobility management network element. For example, the mobility management network element may be the AMF in FIG. 3, or the mobility management network element may be the target AMF in FIG. 5, FIG. 7, or FIG. 8. For example, the method includes:

Step 1001: The mobility management network element obtains information of at least one candidate base station.

For example, the information of at least one candidate base station includes identification information of the tracking area where the candidate base station is located, or at least one item of identification information of the candidate base station.

The at least one candidate base station here may be at least one candidate base station located in the service area of the mobility management network element, that is, a candidate base station located in the second set of candidate base stations.

Optionally, the mobility management network element does not change during the handover process. In this scenario, acquiring the information of the at least one candidate base station by the mobility management network element includes: the first mobility management network element acquires the information of the at least one candidate base station from the source base station. For example, the source base station may be the source base station in FIG. 3. For this, please refer to the description of step 302 in FIG. 3, which will not be repeated here.

Or, the mobility management network element changes during the handover. The mobility management network element is the target mobility management network element after the change. Then, in this scenario, acquiring the information of at least one candidate base station by the mobility management network element includes: the target mobility management network element acquires the information of the at least one candidate base station from the source mobility management network element. For example, the source mobility management network element may be the source AMF in FIG. 5, FIG. 7 or FIG. 8. For this, please refer to the description of step 507 in FIG. 6, step 707 in FIG. 7, or step 810 in FIG. 8, which will not be repeated here.

Step 1002: The mobility management network element obtains network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station.

Optionally, step 1002 includes: the first mobility management network element determines, according to the information of the at least one candidate base station, a slice supported by the tracking area where the at least one candidate base station is located.

Optionally, step 1002 includes: the first mobility management network element determines the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station and the associated information; wherein, the associated information includes the at least one candidate base station. Correspondence between the information of one candidate base station and the network slice information supported by the at least one candidate base station. For example, the association information may be the correspondence between each TA stored in the AMF and the TA supported by it, as shown in Table 3 above.

For step 1002, reference may be made to the description of step 303 in FIG. 3, and details are not described herein again.

Step 1003: The mobility management network element determines a target base station from the at least one candidate base station according to the network slice information supported by the at least one candidate base station and the network slice information associated with the current session of the terminal device. The target base station supports slices associated with the current session of the terminal device.

For step 1003, reference may be made to the description of step 304 in FIG. 3, and details are not described herein again.

Step 1004: The mobility management network element sends a request message to the target base station, where the request message is used to switch the terminal device from the source base station to the target base station.

Through the above method, since the first mobility management network element considers the slices supported by each candidate base station or its location and the network slices associated with the current session of the terminal device when determining the target base station, the determined target base station can support the current session of the terminal device. Session association slices, therefore, in a scenario where a terminal device is switched from a source base station to a target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device's business and improving user experience.

With reference to the description of FIG. 5 to FIG. 9, as shown in FIG. 11, the present application provides a handover method. This method is executed by the source mobility management network element. The source mobility management network element refers to the mobility management network element that serves the terminal device before the mobility management network element is switched (reallocation). For example, the source mobility management network element may be the source AMF in FIG. 5, FIG. 7 or FIG. 8. For example, the method includes:

Step 1101: The source mobility management network element receives information of at least one candidate base station from the source base station.

Step 1102: The source mobility management network element determines a target mobility management network element.

Step 1103: The source mobility management network element sends the information of the at least one candidate base station and the information of the network slice associated with the current session of the terminal device to the target mobility management network element, and the information of the at least one candidate base station Used for determining the target base station, the target base station supports a network slice associated with the current session of the terminal device.

According to the above method, the source mobility management network element determines the target mobility management network element, and sends the information of at least one candidate base station received from the source base station and the network slice associated with the current session of the terminal device to the target mobility management network element When determining the target base station, the target mobility management network element can consider the slices supported by each candidate base station or its location and the network slices associated with the current session of the terminal device. The determined target base station can support the current session association with the terminal device Therefore, in the scenario where the terminal device is switched from the source base station to the target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device’s business and improving the user experience.

Optionally, the method further includes: the source mobility management network element determines that the source mobility management network element cannot continue to serve the terminal device. For example, when the source mobility management network element does not have an interface with any base station in the at least one candidate base station, or when the at least one candidate base station is connected to the source mobility management network element, all base stations are connected. The network slice associated with the current session of the terminal device is not supported, and the source mobility management network element determines that the source mobility management network element cannot continue to serve the terminal device.

Optionally, the source mobility management network element determining the target mobility management network element includes: the source mobility management network element sends a request message to the first network element, and the request message is used to request the target mobility management Network element information, where the first network element includes NRF or NSSF. For example, the source mobility management network element obtains the TA information where at least one candidate base station is located, and the request message includes the TA information where the at least one candidate base station is located.

When the first network element is an NRF, the source mobility management network element determining a target mobility management network element includes: the source mobility management network element receives at least one mobility management network element from the NRF Identification information (for example, GUAMI), the source mobility management network element selects the target mobility management network element.

For example, selecting the target mobility management network element by the source mobility management network element includes: the source mobility management network element determines from the at least one mobility management network element that it is related to the source mobility management network element. The first mobility management network element whose network element is located in the same mobility management network element set is the target mobility management network element. For this, please refer to the description of steps 504 to 506 in FIG. 5, which will not be repeated here. The way the source mobility management network element determines the target mobility management network element through the NRF takes into account the compatibility of the existing process and is easy to implement.

Alternatively, the source mobility management network element selecting the target mobility management network element includes: when the mobility management network element among the at least one mobility management network element and the source mobility management network element are located in different mobile locations A collection of network elements for mobility management, the source mobility management network element sends to the network slice selection function network element the identification information of the tracking area where each candidate base station is located in the at least one candidate base station and the network associated with the current session of the terminal device Slice information; the source mobility management network element receives candidate target mobility management network element information from the network slice selection function network element, and determines the target mobility according to the candidate target mobility management network element information Manage network elements. For this, please refer to the description of steps 806 to 809 in FIG. 8, which will not be repeated here. This method takes into account the compatibility of existing processes and the accuracy and low latency of finding a suitable target mobility management network element.

When the first network element is an NSSF, the request further includes slice information associated with the current session of the terminal device, wherein the source mobility management network element determining the target mobility management network element includes: The source mobility management network element receives target mobility management network element information from the NSSF, and determines the target mobility management network element according to the target mobility management network element information. For this, please refer to the description of steps 704 to 706 in FIG. 7, which will not be repeated here. Since NSSF senses the slices supported by each mobility management network element, and at the same time, it also senses the slices supported by TA under each mobility management network element. Therefore, the candidate target mobility management network element determined by NSSF supports slices associated with the current session of the UE. , Can accurately and quickly find the appropriate target mobility management network element, and shorten the handover delay.

The above-mentioned target mobility management network element information includes the information of the set (AMF set) where the target mobility management network element is located or the identification information (GUAMI) of the candidate target mobility management network element.

With reference to the description of FIG. 3 to FIG. 9, as shown in FIG. 12, the present application provides a method for determining a target base station. This method is executed by the source base station. The source base station refers to the base station that serves the terminal device before handover. For example, the source base station may be the source base station in FIG. 3, FIG. 5, FIG. 7 or FIG. 8. For example, the method includes:

Step 1201: The source base station sends information of at least one candidate base station to the mobility management network element, where the information of the at least one candidate base station is used to determine the target base station.

Step 1202: The source base station receives a handover command, where the handover command is used to switch the terminal device from the source base station to the target base station.

Through the above method, the source base station sends the information of at least one candidate base station to the mobility management network element, so that the mobility management network element can consider each candidate base station or the slice supported by the location when determining the target base station, and the determined target base station can support and The current session of the terminal device is associated with the slice. Therefore, in the scenario where the terminal device is switched from the source base station to the target base station, the current session will not be interrupted, thereby maintaining business continuity for the terminal device service and improving user experience.

The foregoing mainly introduces the solutions provided by the embodiments of the present application from the perspective of interaction between various network elements. Correspondingly, an embodiment of the present application also provides a communication device. The communication device may be the mobility management network element in the foregoing method embodiment, or a device including the foregoing mobility management network element, or may be a mobility management network element. Alternatively, the communication device may be the base station in the foregoing method embodiment, or a device including the foregoing base station, or may be a component that can be used in a base station. It can be understood that, in order to realize the above-mentioned functions, the communication device includes hardware structures and/or software modules corresponding to each function. Those skilled in the art should easily realize that in combination with the units and algorithm steps of the examples described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software-driven hardware depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.

For example, taking the communication device as the mobility management network element in the foregoing method embodiment as an example, FIG. 13 shows a schematic structural diagram of a mobility management network element 1300. The mobility management network element 1300 includes a transceiver module 1301 and a processing module 1302. The transceiver module 1301 may also be referred to as a transceiver unit to implement a transceiver function, for example, it may be a transceiver circuit, a transceiver, a transceiver or a communication interface. The processing module 1302 may also be referred to as a processing unit to implement processing functions, and may be, for example, a processing circuit, a processor, or a processor.

In an embodiment, the mobility management network element can perform the operations of the mobility management network element in the above 10. For example, the transceiver module 1301 is used to obtain information about at least one candidate base station. The processing module 1302 is configured to obtain network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station; according to the network slice information supported by the at least one candidate base station and the network slice information associated with the current session of the terminal device Information, a target base station is determined from the at least one candidate base station, where the target base station supports a network slice associated with the current session of the terminal device. The transceiver module 1301 is further configured to send a request message to the target base station, where the request message is used to switch the terminal device from the source base station to the target base station.

Optionally, the transceiver module 1301 is configured to receive information of the at least one candidate base station from the source base station; or, to receive information of the at least one candidate base station from a source mobility management network element, the mobility management The network element is the target mobility management network element.

Optionally, the processing module 1302 is configured to determine the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station and the associated information; wherein the associated information includes the information of the at least one candidate base station and Correspondence between the network slice information supported by the at least one candidate base station.

Optionally, the processing module 1302 is configured to determine, according to the information of the at least one candidate base station, a slice supported by the tracking area where the at least one candidate base station is located.

Optionally, the information of the at least one candidate base station includes identification information of the tracking area where the at least one candidate base station is located, or at least one item of identification information of the at least one candidate base station.

In another embodiment, the mobility management network element can perform the operations of the source mobility management network element in 11 above. For example, the processing module 1302 is used to determine the target mobility management network element. The transceiver module 1301 is configured to receive information about at least one candidate base station from a source base station; send information about the at least one candidate base station and information about the network slice associated with the current session of the terminal device to the target mobility management network element, and the at least The information of a candidate base station is used to determine a target base station, and the target base station supports a network slice associated with the current session of the terminal device.

Optionally, the processing module 1302 is further configured to determine that the source mobility management network element cannot continue to serve the terminal device. For example, when the source mobility management network element is not connected to any base station in the at least one candidate base station, or when the at least one candidate base station is connected to the source mobility management network element, all base stations are connected to the source mobility management network element. The network slice associated with the current session of the terminal device is not supported, and the processing module 1302 determines that the source mobility management network element cannot continue to serve the terminal device.

Optionally, the processing module 1302 is further configured to send a request message to the first network element through the transceiver module 1301, where the request message is used to request information about the target mobility management network element, wherein the first network The elements include network storage function network elements or network slice selection function network elements.

Optionally, the processing module 1302 is further configured to obtain identification information of the tracking area where each candidate base station in the at least one candidate base station is located; the request message includes the identification information of the tracking area where each candidate base station is located in the at least one candidate base station information.

Optionally, when the first network element is a network storage function network element, the processing module 1302 is configured to receive identification information of at least one mobility management network element from the network storage function network element through the transceiver module 1301; determine The target mobility management network element. Specifically, the first way: the processing module 1302 determines the first mobility management network element that is located in the same mobility management network element set as the source mobility management network element from the at least one mobility management network element Manage network elements for the target mobility. The second way: when the mobility management network element of the at least one mobility management network element and the source mobility management network element are located in different mobility management network element sets, the processing module 1302 is configured to communicate to the network through the transceiver module 1301 The slice selection function network element sends the identification information of the tracking area of each candidate base station in the at least one candidate base station and the information of the network slice associated with the current session of the terminal device; and receives the candidate target from the network slice selection function network element The information of the mobility management network element, the target mobility management network element is determined according to the information of the candidate target mobility management network element, wherein the candidate target mobility management network element supports the association with the current session of the terminal device Network slicing.

Optionally, when the first network element is a network slice selection function network element, the request message further includes information about the network slice associated with the current session of the terminal device, and the processing module 1302 is configured to use the transceiver module 1301 to download The network slice selection function network element receives the information of the candidate target mobility management network element, and determines the target mobility management network element according to the information of the candidate target mobility management network element, wherein the candidate target mobility management The network element supports the network slice associated with the current session of the terminal device.

Optionally, the information of the candidate target mobility management network element includes information of the set where the candidate target mobility management network element is located or identification information of the candidate target mobility management network element.

In addition, all relevant content of the steps involved in the above method embodiments can be cited in the functional description of the corresponding functional module, which will not be repeated here.

In this embodiment, the mobility management network element 1300 is presented in the form of dividing various functional modules in an integrated manner. The "module" here can refer to a specific ASIC, circuit, processor and memory that executes one or more software or firmware programs, integrated logic circuit, and/or other devices that can provide the above-mentioned functions. In a simple embodiment, those skilled in the art can imagine that the mobility management network element 1300 may adopt the form of the communication device 1500 shown in FIG. 15.

For example, the processor 1501 in the communication device 1500 shown in FIG. 15 may invoke the computer execution instructions stored in the memory 1503 to make the communication device 1500 execute the switching method in the foregoing method embodiment.

Specifically, the functions/implementation process of the transceiver module 1301 and the processing module 1302 in FIG. 13 may be implemented by the processor 1501 in the communication device 1500 shown in FIG. 15 calling computer execution instructions stored in the memory 1503. Alternatively, the function/implementation process of the processing module 1302 in FIG. 13 can be implemented by the processor 1501 in the communication device 1500 shown in FIG. 15 calling a computer execution instruction stored in the memory 1503, and the function of the transceiver module 1301 in FIG. /The realization process can be realized through the communication interface 1504 in the communication device 1500 shown in FIG. 15.

Since the mobility management network element 1300 provided in this embodiment can perform the above-mentioned handover method, the technical effects that can be obtained can refer to the above-mentioned method embodiment, which will not be repeated here.

Taking the communication device as the base station in the foregoing method embodiment as an example, FIG. 14 shows a schematic structural diagram of a base station 1400. The base station 1400 includes a transceiver module 1401 and a processing module 1402. The transceiver module 1401 may also be referred to as a transceiver unit to implement a transceiver function, for example, it may be a transceiver circuit, transceiver, transceiver or communication interface. The processing module 1402 may also be referred to as a processing unit to implement processing functions, and may be, for example, a processing circuit, a processor, or a processor.

In an embodiment, the base station can perform the operations of the source base station in 12 above. For example, the transceiver module 1401 is used to send information about at least one candidate base station. The information about at least one candidate base station is used to determine the target base station. The target base station supports network slices associated with the current session of the terminal device; The terminal device switches from the source base station to the target base station. For example, the information of the at least one candidate base station includes identification information of the tracking area where the at least one candidate base station is located, or at least one item of identification information of the at least one candidate base station.

In this embodiment, the base station 1400 is presented in the form of dividing various functional modules in an integrated manner. The "module" here can refer to a specific ASIC, circuit, processor and memory that executes one or more software or firmware programs, integrated logic circuit, and/or other devices that can provide the above-mentioned functions. In a simple embodiment, those skilled in the art can imagine that the base station 1400 may adopt the form of the communication device 1500 shown in FIG. 15.

For example, the functions/implementation process of the transceiver module 1401 and the processing module 1402 in FIG. 14 can be implemented by the processor 1501 in the communication device 1500 shown in FIG. 15 calling the computer execution instructions stored in the memory 1503. Alternatively, the function/implementation process of the transceiver module 1401 in FIG. 14 may be implemented through the communication interface 1504 in the communication device 1500 shown in FIG. 15.

Since the base station 1400 provided in this embodiment can perform the above-mentioned handover method, the technical effects that can be obtained can refer to the above-mentioned method embodiment, which will not be repeated here.

It should be noted that one or more of the above modules or units can be implemented by software, hardware or a combination of both. When any of the above modules or units are implemented by software, the software exists in the form of computer program instructions and is stored in the memory, and the processor can be used to execute the program instructions and implement the above method flow. The processor can be built in SoC (system on chip) or ASIC, or it can be an independent semiconductor chip. The processor's internal processing is used to execute software instructions to perform calculations or processing, and may further include necessary hardware accelerators, such as field programmable gate array (FPGA), PLD (programmable logic device) , Or a logic circuit that implements dedicated logic operations.

When the above modules or units are implemented in hardware, the hardware can be a CPU, a microprocessor, a digital signal processing (digital signal processing, DSP) chip, a microcontroller unit (MCU), an artificial intelligence processor, an ASIC, Any one or any combination of SoC, FPGA, PLD, dedicated digital circuit, hardware accelerator, or non-integrated discrete device can run necessary software or do not rely on software to perform the above method flow.

Optionally, an embodiment of the present application further provides a communication device (for example, the communication device may be a chip or a chip system), and the communication device includes a processor for implementing the method in any of the foregoing method embodiments. In a possible design, the communication device further includes a memory. The memory is used to store necessary program instructions and data, and the processor can call the program code stored in the memory to instruct the communication device to execute the method in any of the foregoing method embodiments. Of course, the memory may not be in the communication device. When the communication device is a chip system, it may be composed of a chip, or may include a chip and other discrete devices, which is not specifically limited in the embodiment of the present application.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using a software program, it can be implemented in the form of a computer program product in whole or in part. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center. Transmission to another website, computer, server, or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). The computer-readable storage medium may be any available medium that can be accessed by a computer or includes one or more data storage devices such as servers, data centers, etc. that can be integrated with the medium. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).

Although this application has been described in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art can understand and understand by viewing the drawings, the disclosure, and the appended claims in the process of implementing the claimed application. Implement other changes of the disclosed embodiment. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality. A single processor or other unit may implement several functions listed in the claims. Certain measures are described in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

Although the application has been described in combination with specific features and embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary descriptions of the application as defined by the appended claims, and are deemed to cover any and all modifications, changes, combinations or equivalents within the scope of the application. Obviously, those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. In this way, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, then this application is also intended to include these modifications and variations.

Claims

A handover method, characterized in that it comprises:

The mobility management network element obtains information of at least one candidate base station;

Acquiring, by the mobility management network element, network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station;

The mobility management network element determines a target base station from the at least one candidate base station according to the network slice information supported by the at least one candidate base station and the network slice information associated with the current session of the terminal device, wherein the target base station Support network slicing associated with the current session of the terminal device;

The mobility management network element sends a request message to the target base station, where the request message is used to switch the terminal device from the source base station to the target base station.
The method according to claim 1, wherein the information of the at least one candidate base station includes the identification information of the tracking area in which the at least one candidate base station is located, or the identification information of the at least one candidate base station is At least one item.
The method according to claim 1 or 2, wherein the mobility management network element acquiring information of at least one candidate base station comprises:

The mobility management network element receives the information of the at least one candidate base station from the source base station.
The method according to claim 1 or 2, wherein the mobility management network element is a target mobility management network element, wherein the mobility management network element acquiring information of at least one candidate base station includes:

The target mobility management network element receives the information of the at least one candidate base station from the source mobility management network element.
The method according to any one of claims 1 to 4, wherein the mobility management network element acquiring network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station comprises:

Determining, by the mobility management network element, the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station and the associated information;

Wherein, the association information includes the correspondence between the information of the at least one candidate base station and the network slice information supported by the at least one candidate base station.
The method according to any one of claims 1 to 5, wherein the mobility management network element acquiring network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station comprises:

The mobility management network element determines, according to the information of the at least one candidate base station, a slice supported by the tracking area where the at least one candidate base station is located.
A handover method, characterized in that it comprises:

The source mobility management network element receives information about at least one candidate base station from the source base station;

The source mobility management network element determines the target mobility management network element;

The source mobility management network element sends the information of the at least one candidate base station and the information of the network slice associated with the current session of the terminal device to the target mobility management network element, and the information of the at least one candidate base station is used for the target The base station determines that the target base station supports a network slice associated with the current session of the terminal device.
The method according to claim 7, further comprising:

The source mobility management network element determines that the source mobility management network element cannot continue to serve the terminal device.
The method according to claim 8, wherein the determining by the source mobility management network element that the source mobility management network element cannot continue to serve the terminal device comprises:

When there is no connection between the source mobility management network element and the base station in the at least one candidate base station, the source mobility management network element determines that the source mobility management network element cannot continue to serve the terminal device; or

When none of the at least one candidate base station connected to the source mobility management network element supports the network slice associated with the current session of the terminal device, the source mobility management network element determines the source mobility The management network element cannot continue to serve the terminal device.
The method according to any one of claims 7 to 9, wherein the source mobility management network element determining the target mobility management network element comprises:

The source mobility management network element sends a request message to a first network element, where the request message is used to request information about the target mobility management network element, where the first network element includes a network storage function network element or Network slicing selection function network element.
The method according to claim 10, further comprising:

Acquiring, by the source mobility management network element, identification information of the tracking area where each candidate base station is located in the at least one candidate base station;

The request message includes identification information of the tracking area where each candidate base station is located in the at least one candidate base station.
The method according to claim 10 or 11, wherein:

The first network element is a network storage function network element, wherein the source mobility management network element determining the target mobility management network element includes:

Receiving, by the source mobility management network element, identification information of at least one mobility management network element from the network storage function network element;

The source mobility management network element determines the target mobility management network element.
The method according to claim 12, wherein the source mobility management network element determining the target mobility management network element comprises:

The source mobility management network element determines from the at least one mobility management network element that the first mobility management network element located in the same mobility management network element set as the source mobility management network element is the Target mobility management network element.
The method according to claim 12, wherein the source mobility management network element determining the target mobility management network element comprises:

When the mobility management network element of the at least one mobility management network element and the source mobility management network element are located in different mobility management network element sets, the source mobility management network element sends a message to the network slice selection function network element Identification information of the tracking area where each candidate base station is located in the at least one candidate base station and information about the network slice associated with the current session of the terminal device;

The source mobility management network element receives the information of the candidate target mobility management network element from the network slice selection function network element, and determines the target mobility management network element according to the information of the candidate target mobility management network element, Wherein, the candidate target mobility management network element supports a network slice associated with the current session of the terminal device.
The method according to claim 10 or 11, wherein the first network element is a network slice selection function network element, and the request message further includes network slice information associated with the current session of the terminal device, wherein , The source mobility management network element determining the target mobility management network element includes:

The source mobility management network element receives the information of the candidate target mobility management network element from the network slice selection function network element, and determines the target mobility management network element according to the information of the candidate target mobility management network element, Wherein, the candidate target mobility management network element supports a network slice associated with the current session of the terminal device.
The method according to claim 14 or 15, wherein the information of the candidate target mobility management network element comprises information of the set where the candidate target mobility management network element is located or the candidate target mobility management network The identification information of the meta.
The method according to any one of claims 7 to 16, wherein the information of the at least one candidate base station comprises identification information of a tracking area in which the at least one candidate base station is located, or the at least one candidate base station At least one item of identification information of the base station.
A mobility management network element, characterized in that, the mobility management network element includes:

The transceiver module is used to obtain information of at least one candidate base station; and

The processing module is configured to obtain the network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station; according to the network slice information supported by the at least one candidate base station and the network slice information associated with the current session of the terminal device Information, determining a target base station from the at least one candidate base station, where the target base station supports a network slice associated with the current session of the terminal device;

The transceiver module is further configured to send a request message to the target base station, where the request message is used to switch the terminal device from the source base station to the target base station.
The mobility management network element according to claim 18, wherein:

The transceiver module is configured to receive information of the at least one candidate base station from the source base station; or,

The transceiver module is configured to receive information of the at least one candidate base station from a source mobility management network element, and the mobility management network element is a target mobility management network element.
The mobility management network element according to claim 18 or 19, wherein the processing module is configured to determine the network slice information supported by the at least one candidate base station according to the information and associated information of the at least one candidate base station; Wherein, the association information includes the correspondence between the information of the at least one candidate base station and the network slice information supported by the at least one candidate base station.
The mobility management network element according to any one of claims 18 to 20, wherein the processing module is configured to determine the track where the at least one candidate base station is located according to the information of the at least one candidate base station The slices supported by the zone.
A source mobility management network element, characterized in that, the source mobility management network element includes:

The processing module is used to determine the target mobility management network element;

The transceiver module is configured to receive information about at least one candidate base station from the source base station; send the information about the at least one candidate base station and the information about the network slice associated with the current session of the terminal device to the target mobility management network element, and the at least The information of a candidate base station is used to determine a target base station, and the target base station supports a network slice associated with the current session of the terminal device.
The source mobility management network element according to claim 22, wherein the processing module is further configured to determine that the source mobility management network element cannot continue to serve the terminal device.
The source mobility management network element according to claim 22 or 23, wherein the processing module is configured to send a request message to the first network element through the transceiver module, and the request message is used to request the target Information about the mobility management network element, where the first network element includes a network storage function network element or a network slice selection function network element.
The source mobility management network element according to claim 24, wherein the processing module is further configured to obtain identification information of the tracking area where each candidate base station is located in the at least one candidate base station;

The request message includes identification information of the tracking area where each candidate base station is located in the at least one candidate base station.
The mobility management network element according to any one of claims 18 to 20 or the source mobility management network element according to any one of claims 21 to 25, wherein the information of the at least one candidate base station It includes at least one item of the identification information of the tracking area where the at least one candidate base station is located, or the identification information of the at least one candidate base station.
A handover system is characterized in that it comprises:

The source base station is used to send information about at least one candidate base station;

The mobility management network element is configured to receive information of the at least one candidate base station from the source base station; obtain network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station; The network slice information supported by the candidate base station and the information about the network slice associated with the current session of the terminal device are used to determine a target base station from the at least one candidate base station, wherein the target base station supports the network slice associated with the current session of the terminal device ；

The target base station is configured to receive a request message from the mobility management network element, where the request message is used to switch the terminal device from the source base station to the target base station.
A handover system is characterized in that it comprises:

The source base station is used to send information about at least one candidate base station;

A source mobility management network element, configured to receive information about the at least one candidate base station from the source base station; determine a target mobility management network element; and send information about the at least one candidate base station to the target mobility management network element Information about the network slice associated with the current session of the terminal device;

The target mobility management network element is configured to obtain network slice information supported by the at least one candidate base station according to the information of the at least one candidate base station; according to the network slice information supported by the at least one candidate base station and the terminal Information about the network slice associated with the current session of the device, determining a target base station from the at least one candidate base station, where the target base station supports the network slice associated with the current session of the terminal device;

The target base station is configured to receive a request message from the target mobility management network element, where the request message is used to switch the terminal device from the source base station to the target base station.
The system according to claim 27 or 28, wherein the information of the at least one candidate base station includes identification information of the tracking area in which the at least one candidate base station is located, or identification information of the at least one candidate base station At least one of.