A method and apparatus for selecting a residential area

Abstract

This application provides a method and apparatus for cell selection. The method includes: a terminal device determining first network slice information, the first network slice information including the identifier of at least one network slice; the terminal device receiving second network slice information sent from a camped cell, the second network slice information including the identifier of at least one network slice; and the terminal device performing cell reselection based on the first network slice information and the second network slice information. Implementing this application embodiment can improve the efficiency of cell selection, facilitate the rapid and effective selection of suitable cells, and reduce cell selection latency and resource overhead.

Description

Technical Field

[0001] This invention relates to the field of wireless communication, and more particularly to a method and apparatus for cell selection. Background Technology

[0002] With the rapid development of wireless communication technology, 5G (5th Generation) wireless communication technology has become a hot topic in the industry. 5G will support diverse application needs, including higher speeds and greater bandwidth access capabilities, lower latency and highly reliable information exchange, and access and management of larger-scale, lower-cost machine-type communication devices. Supporting the ubiquitous needs of various vertical industries while ensuring energy efficiency are key factors for the application of 5G.

[0003] Therefore, 5G introduces the important concept of network slicing. A network slice is a combination of network functions and corresponding resource requirements that realize communication services and network capabilities, including the core network (CN) and the radio access network (RAN). A network slice constitutes an end-to-end logical network, thereby meeting the performance requirements of one or more network services for the slice requester. Multiple network slices are deployed within a CN to meet the needs of different users and different services; a RAN can support multiple network slices. Typically, the network slices supported by a cell controlled by a RAN device are a subset of the network slices deployed in the CN, and the network slices supported by cells controlled by different RAN devices can also be different. In other words, different cells have different network slice support capabilities. It is possible that a terminal device can initiate a certain service in a first cell, but cannot initiate the same service in a second cell, because the first cell supports the network slice to which the service belongs, but the second cell does not.

[0004] In existing technologies, terminal devices select cells based on factors such as cell link quality and priority. However, because different cells have varying capabilities in supporting network slicing, the cell selected by the terminal device may not support the network slices required by the device. Currently, there is no suitable solution for effectively selecting appropriate cells when considering network slicing. Summary of the Invention

[0005] This application provides a cell selection method that can improve the efficiency of cell selection, quickly and effectively select suitable cells, and reduce cell selection latency and resource overhead.

[0006] The following sections introduce this application from multiple perspectives. It is easy to understand that the implementation methods of these multiple aspects can be referenced from each other.

[0007] Firstly, this application provides a cell selection method, the execution subject of which can be a terminal device or a chip applied in the terminal device. The method includes: the terminal device determining first network slice information, the first network slice information containing identifiers of at least one network slice; the terminal device receiving second network slice information sent from a camped cell, the second network slice information containing identifiers of at least one network slice; and the terminal device performing cell reselection based on the first network slice information and the second network slice information.

[0008] As can be seen, the method provided in this application embodiment enables a terminal device in the RRC non-connected state to select a suitable cell that supports the service when it is about to initiate a service, so that the terminal device can quickly access the suitable cell when it subsequently initiates a service, effectively reducing the latency of service establishment and reducing signaling overhead.

[0009] In one possible implementation, the first network slice information is used to indicate the identifier of at least one network slice to which at least one service to be initiated by the terminal device belongs.

[0010] In one possible implementation, the second network slice information includes the identifier of at least one network slice supported by the hosted cell.

[0011] In one possible implementation, the second network slice information includes the identifier of at least one network slice supported by the stationed cell and the identifier of at least one network slice supported by at least one neighboring cell of the stationed cell.

[0012] In one possible implementation, the terminal device performs cell reselection based on the first network slice information and the second network slice information, including: when the network slice identifier of the camping cell does not contain the first network slice identifier, the terminal device performs cell reselection; wherein, the network slice identifier of the camping cell is used to indicate the identifier of at least one network slice contained in the second network slice information, and the first network slice identifier is used to indicate the identifier of at least one network slice contained in the first network slice information.

[0013] In one possible implementation, the terminal device performs cell reselection based on the first network slice information and the second network slice information, including: when the network slice identifier of the camping cell does not contain the first network slice identifier, and at least one neighboring cell network slice identifier partially or completely contains the first network slice identifier, the terminal device performs cell reselection; wherein, the network slice identifier of the camping cell is used to indicate the identifier of at least one network slice supported by the camping cell, the first network slice identifier is used to indicate the identifier of at least one network slice contained in the first network slice information, and the neighboring cell network slice identifier is used to indicate the identifier of at least one network slice supported by a neighboring cell of the camping cell.

[0014] In one possible implementation, the terminal device performs cell reselection based on the first network slice information and the second network slice information, including: when the network slice identifier portion of the camping cell contains the first network slice identifier, and the number of network slices at the intersection of at least one neighboring cell network slice identifier and the first network slice identifier is greater than the number of network slices at the intersection of the camping cell network slice identifier and the first network slice identifier, the terminal device performs cell reselection; wherein, the camping cell network slice identifier is used to indicate the identifier of at least one network slice supported by the camping cell, the first network slice identifier is used to indicate the identifier of at least one network slice contained in the first network slice information, and the neighboring cell network slice identifier is used to indicate the identifier of at least one network slice supported by at least one neighboring cell of the camping cell.

[0015] In one possible implementation, the terminal device performs cell reselection based on the first network slice information and the second network slice information, including: when the number of network slices at the intersection of the camping cell network slice identifier and the first network slice identifier is equal to the number of network slices at the intersection of at least one neighboring cell network slice identifier and the first network slice identifier, and the link quality of the camping cell is lower than the link quality of the at least one neighboring cell, the terminal device performs cell reselection; wherein, the camping cell network slice identifier is used to indicate the identifier of at least one network slice supported by the camping cell, the first network slice identifier is used to indicate the identifier of at least one network slice included in the first network slice information, and the neighboring cell network slice identifier is used to indicate the identifier of at least one network slice supported by at least one neighboring cell of the camping cell.

[0016] In one possible implementation, the terminal device performs cell reselection by selecting the neighboring cell with the largest number of network slices at the intersection of the neighboring cell's network slice identifier and the first network slice identifier from the at least one neighboring cell for camping.

[0017] In one possible implementation, the terminal device performs cell reselection by: when the number of network slices at the intersection of multiple neighboring cell network slice identifiers and the first network slice identifier is the largest, the terminal device selects the neighboring cell with the highest link quality to camp on among the multiple neighboring cells; or, the terminal device selects the neighboring cell with the highest priority to camp on among the multiple neighboring cells.

[0018] In one possible implementation, the terminal device performs cell reselection by: the terminal device selecting a neighboring cell with the highest link quality to camp on in the at least one neighboring cell; or the terminal device selecting a neighboring cell with the highest priority to camp on in the at least one neighboring cell.

[0019] Secondly, this application provides a method for PLMN selection, which can be executed by a terminal device or by a chip applied in the terminal device. The method includes: the terminal device determining third network slice information, the third network slice information containing the identifier of at least one network slice; and the terminal device selecting a PLMN based on the third network slice information.

[0020] As can be seen, the method provided in this application embodiment enables terminal devices in the RRC non-connected state to consider the network slice to which the services they may subsequently initiate belong when selecting a PLMN, so that the terminal device can select a suitable PLMN. This allows the terminal device to quickly select a cell for access in a suitable PLMN when it subsequently initiates a service, effectively reducing the latency of service establishment and reducing signaling overhead.

[0021] In one possible implementation, the third network slice information is used to indicate the identifier of at least one network slice to which at least one service desired by the terminal device belongs.

[0022] In one possible implementation, the terminal device obtains PLMN subscription information, which includes a set of multiple subscribed PLMN identifiers of the terminal device and fourth network slice information of each subscribed PLMN. The fourth network slice information is used to indicate the identifier of at least one network slice supported by the subscribed PLMN.

[0023] In one possible implementation, the terminal device acquires network PLMN information, which includes the identifier of at least one PLMN in the network acquired by the terminal device on at least one RF channel.

[0024] In one possible implementation, the terminal device determines a potential PLMN set based on the set of subscribed PLMN identifiers and the network PLMN information; the potential PLMN set is the intersection of the set of subscribed PLMN identifiers and the network PLMN information.

[0025] In one possible implementation, the terminal device determines a set of candidate PLMNs from the set of potential PLMNs based on the third network slice information; the set of candidate PLMNs is the identifier of one or more PLMNs in the set of potential PLMNs that support at least one network slice identified by the third network slice information.

[0026] In one possible implementation, the terminal device determines the selected PLMN to be the contracted PLMN with the largest number of network slices at the intersection of the fourth network slice information and the third network slice information in the candidate PLMN set.

[0027] In one possible implementation, the terminal device obtains PLMN subscription information, which includes a set of multiple subscribed PLMN identifiers of the terminal device, the RAT identifier of each subscribed PLMN, and the fifth network slice information of each RAT under each subscribed PLMN. The fifth network slice information is used to indicate the identifier of at least one network slice supported by a RAT under the subscribed PLMN.

[0028] In one possible implementation, the terminal device acquires network PLMN information, which includes the identifier of at least one PLMN in the network acquired by the terminal device on at least one RF channel.

[0029] In one possible implementation, the terminal device determines the selected PLMN from the aforementioned network PLMN information based on the third network slice information and the fifth network slice information. The selected PLMN is the contracted PLMN with the largest number of network slices at the intersection of the fifth network slice information and the third network slice information in the candidate PLMN set.

[0030] Thirdly, this application provides another method for cell selection, which can be performed by a terminal device or a chip applied in the terminal device. The method includes: a NAS entity sending a sixth network slice identifier to an AS entity, the sixth network slice identifier containing the identifier of a network slice; the AS entity listening to cell broadcast messages; and the AS entity performing cell selection based on the sixth network slice identifier.

[0031] As can be seen, the method provided in this application embodiment enables the AS entity of the terminal device in the RRC non-connected state to consider a network slice to which the service to be initiated may belong when selecting a cell, so that the AS entity can select a suitable cell to camp on, so that the NAS entity can quickly access the appropriate cell when initiating services, effectively reducing the latency of service establishment and reducing signaling overhead.

[0032] In one possible implementation, the sixth network slice identifier is used to indicate the identifier of the network slice to which the terminal device belongs in the subsequent services it is expected to initiate.

[0033] In one possible implementation, the terminal device can select one cell from multiple cells in the selected PLMN to camp on based on the cell's RSRP, priority, or preset criteria.

[0034] In one possible implementation, the terminal device selects one cell from multiple cells in one of the selected RATs in the selected PLMN for camping, based on the priority of the RAT or a preset criterion.

[0035] Fourthly, this application provides another method for cell selection, which can be performed by a terminal device or a chip applied in the terminal device. The method includes: a NAS entity sending a seventh network slice identifier to an AS entity, the seventh network slice identifier containing identifiers of multiple network slices; the AS entity listening to cell broadcast messages; and the AS entity performing cell selection based on the sixth network slice identifier.

[0036] As can be seen, the method provided in this application embodiment enables the AS entity of the terminal device in the RRC non-connected state to consider multiple network slices to which different services belong when selecting cells, so that the AS entity can select a suitable cell to camp on, so that the NAS entity can quickly access the appropriate cell when initiating services later, effectively reducing the latency of service establishment and reducing signaling overhead.

[0037] In one possible implementation, the seventh network slice identifier is used to indicate the identifiers of multiple network slices to which the terminal device belongs in the multiple services that it subsequently intends to initiate.

[0038] In one possible implementation, the AS entity can select one cell from multiple cells in the selected PLMN for camping based on the cell's RSRP, priority, or preset criteria.

[0039] Fifthly, this application provides another method for cell selection, which can be performed by a terminal device or a chip applied in the terminal device. The method includes: a NAS entity sending a seventh network slice identifier to an AS entity, the seventh network slice identifier containing identifiers of multiple network slices; the AS entity listening to cell broadcast messages; and the AS entity performing cell selection based on the seventh network slice identifier.

[0040] As can be seen, the method provided in this application embodiment enables the AS entity of the terminal device in the RRC non-connected state to consider the network slice to which one or more services that may be initiated later belong when selecting a cell, so that the AS entity can select a suitable cell to camp on, so that the NAS entity can quickly access the appropriate cell when initiating services later, effectively reducing the latency of service establishment and reducing signaling overhead.

[0041] In one possible implementation, the seventh network slice identifier is used to indicate the identifiers of multiple network slices to which the terminal device belongs in the multiple services that it subsequently intends to initiate.

[0042] In one possible implementation, if the network slice identifiers supported by each cell obtained by the AS entity from the broadcast message contain the seventh network slice identifier to varying degrees, the AS entity selects the cell that can support up to the seventh network slice for camping.

[0043] In one possible implementation, the AS entity can select one cell from multiple cells in the selected PLMN for camping based on the cell's RSRP, priority, or preset criteria.

[0044] Sixthly, this application provides a communication device, which may be a terminal device, a device within a terminal device, or a device compatible with a terminal device. The communication device may also be a chip system. The communication device is used to execute the methods in the first aspect or any possible implementation thereof, the second aspect or any possible implementation thereof, the third aspect or any possible implementation thereof, the fourth aspect or any possible implementation thereof, or the fifth aspect or any possible implementation thereof. The functions of the communication device can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more units corresponding to the above functions. These units can be software and / or hardware. The operations performed by the communication device and its beneficial effects can be found in the methods and beneficial effects described in the first to fifth aspects above; repetitions will not be repeated.

[0045] In a seventh aspect, this application provides a communication device, the communication device including a processor, wherein when the processor calls a computer program in memory, a method in the first aspect or any possible implementation of the first aspect, or any possible implementation of the second aspect, or any possible implementation of the third aspect, or any possible implementation of the fourth aspect, or any possible implementation of the fifth aspect is executed.

[0046] Eighthly, this application provides a communication device, the communication device including a processor, a memory, and a transceiver, the transceiver being used to receive a channel or signal, or to transmit a channel or signal; the memory being used to store program code; the processor being used to call the program code from the memory to execute a method in the first aspect or any possible implementation of the first aspect, or any possible implementation of the second aspect, or any possible implementation of the third aspect, or any possible implementation of the fourth aspect, or any possible implementation of the fifth aspect.

[0047] Ninthly, this application provides a communication device, the communication device including a processor and an interface circuit, the interface circuit being configured to receive code instructions and transmit them to the processor; the processor executing the code instructions to perform a method in the first aspect or any possible implementation of the first aspect, or any possible implementation of the second aspect, or any possible implementation of the third aspect, or any possible implementation of the fourth aspect, or any possible implementation of the fifth aspect.

[0048] In a tenth aspect, this application provides a computer-readable storage medium for storing instructions that, when executed, cause the method in the first aspect or any possible implementation thereof, or the second aspect or any possible implementation thereof, or the third aspect or any possible implementation thereof, or the fourth aspect or any possible implementation thereof, or the fifth aspect or any possible implementation thereof to be implemented.

[0049] In one aspect, this application provides a computer program product including instructions that, when executed, cause the method in the first aspect or any possible implementation of the first aspect, or any possible implementation of the second aspect, or any possible implementation of the third aspect, or any possible implementation of the fourth aspect, or any possible implementation of the fifth aspect to be implemented.

[0050] In a twelfth aspect, this application provides a chip including logic circuitry and an input / output interface. The input / output interface is used to communicate with a module outside the chip. The logic circuitry is used to run computer programs or instructions to implement the methods in the first aspect or any possible implementation of the first aspect, or the second aspect or any possible implementation of the second aspect, or the third aspect or any possible implementation of the third aspect, or the fourth aspect or any possible implementation of the fourth aspect, or the fifth aspect or any possible implementation of the fifth aspect.

[0051] These and other aspects of the invention will become more apparent from the following description of several embodiments. Attached Figure Description

[0052] The following is a brief description of the accompanying drawings used in the embodiments of this application or in the description of the prior art:

[0053] Figure 1 This is a schematic diagram of a communication system provided in an embodiment of this application;

[0054] Figure 2 This is a schematic diagram of the protocol stack of a terminal device provided in an embodiment of this application;

[0055] Figure 3 This is a schematic flowchart of a cell reselection method provided in an embodiment of this application;

[0056] Figure 4 This is a schematic flowchart of a PLMN selection method provided in an embodiment of this application;

[0057] Figure 5 This is a schematic flowchart of a cell selection method provided in an embodiment of this application;

[0058] Figure 6 This is a schematic flowchart of another cell selection method provided in an embodiment of this application;

[0059] Figure 7 This is a schematic flowchart of another cell selection method provided in the embodiments of this application;

[0060] Figure 8 This is a schematic flowchart of another cell selection method provided in the embodiments of this application;

[0061] Figure 9 This is a schematic flowchart of another cell reselection method provided in an embodiment of this application;

[0062] Figure 10 This is a schematic flowchart of a cell reselection method provided in an embodiment of this application;

[0063] Figure 11 This is a schematic flowchart of another cell reselection method provided in the embodiments of this application;

[0064] Figure 12 This is a schematic block diagram of a terminal device provided in an embodiment of this application;

[0065] Figure 13 This is another schematic block diagram of the terminal device provided in the embodiments of this application;

[0066] Figure 14 This is a schematic block diagram of the structure of a chip provided in an embodiment of this application. Detailed Implementation

[0067] The embodiments of this application will now be described with reference to the accompanying drawings.

[0068] In this application, the term "exemplary" is used to mean "serving as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use the invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that the invention can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of the invention with unnecessary detail. Therefore, the invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0069] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0070] In this article, the terms "system" and "network" are often used interchangeably.

[0071] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0072] The technical solutions of this application can be applied to various wireless communication systems, such as: Long Term Evolution (LTE) systems, 5th generation (5G) mobile communication systems, new radio (NR) communication systems, next generation (NG) communication systems, and future mobile communication systems.

[0073] In a wireless communication system, a terminal device connects to a RAN device via a wireless link, and then communicates with other terminal devices or accesses the wireless internet via a CN device connected to the RAN device. Typically, a terminal device wirelessly connects to one RAN device to achieve communication. Figure 1This diagram illustrates a wireless communication system 100 according to an embodiment of this application. Terminal device 120 establishes a wireless connection with RAN device 140 via an air interface and accesses the core network 160. In practical systems, to meet wireless network coverage requirements, multiple RAN devices are typically deployed in an area, and the cells controlled by different RAN devices need to provide seamless coverage as much as possible. Figure 1 As shown, RAN devices 142, 144, and 146 are deployed around RAN device 140. Different RAN devices can have interfaces for communication with each other, such as X2 or Xn interfaces. In one possible scenario, these RAN devices operate on the same frequency band and are deployed in different geographical locations, with the cells they control collectively providing seamless coverage. For example, there may be a certain degree of overlap between the cells controlled by RAN device 140 and those controlled by RAN device 142. This overlap area should generally not be too large or too small; determining the size of the overlap area requires considering the trade-off between interference between cells on the same frequency and the handover performance between cells. In another possible scenario, some RAN devices operate on different frequency bands, forming heterogeneous network coverage. For example, the cell controlled by RAN device 140 operates on a lower frequency band and has a larger coverage area, while the cell controlled by RAN device 142 operates on a higher frequency band and has a smaller coverage area. These RAN devices can be deployed in the same or different geographical locations, and the cells they control can have completely overlapping coverage areas. For example, RAN device 140 operates on a lower frequency band, RAN device 142 operates on a higher frequency band, and the coverage area of ​​the cell controlled by RAN device 140 can completely or mostly cover the coverage area of ​​the cell controlled by RAN device 142.

[0074] In practical systems, Figure 1The RAN equipment shown can be a next-generation base station, such as a next-generation Node B (gNB) or a next-generation evolved Node B (ng-eNB), or an access point (AP) in a Wireless Local Area Network (WLAN), or an evolved Node B (eNB or eNodeB) in LTE, or a relay station or access point, or vehicle-mounted equipment, wearable devices, and transmission and reception points (TRPs), etc. It should be understood that terminal devices communicate with RAN devices through transmission resources (e.g., frequency domain resources, time domain resources, code domain resources, etc.) used by one or more cells managed by RAN devices. These cells can be macrocells, hypercells, or small cells. Small cells can include metro cells, microcells, pico cells, femtocells, etc. These small cells have the characteristics of small coverage area and low transmission power, and are suitable for providing high-speed data transmission services. Figure 1The terminal equipment in this context can also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent, or user device. The terminal equipment can be a station (ST) in a WLAN, a cellular phone, cordless phone, SIP phone, wireless local loop (WLL) station, personal digital assistant (PDA) device, handheld device with wireless communication capabilities, relay device, computing device, or other processing device coupled to a wireless modem, in-vehicle device, wearable device, and next-generation communication system, such as terminal equipment in a 5G network or a future evolved public land mobile network (PLMN). As an example and not a limitation, in this embodiment, the terminal equipment can also be a wearable device. Wearable devices can also be called wearable smart devices, a general term for devices that utilize wearable technology to intelligently design and develop everyday wearables, such as glasses, gloves, watches, clothing, and shoes. Wearable devices are portable devices worn directly on the body or integrated into a user's clothing or accessories. Wearable devices are not merely hardware devices; they achieve powerful functionality through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include those with comprehensive functions, large sizes, and the ability to perform complete or partial functions without relying on a smartphone, such as smartwatches or smart glasses. They also include devices focused on specific applications that require interaction with other devices like smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0075] To facilitate understanding, several concepts involved in the embodiments of this application are first introduced. It should be understood that the following explanations of concepts may be limited by the specific circumstances of the embodiments of this application, but do not mean that this application is limited to only that specific situation. The explanations of the following concepts may also differ depending on the specific circumstances of different embodiments:

[0076] 1) RRC States: RRC states typically include three types: RRC Connected (RRC_CONNECTED), RRC Idle (RRC_IDLE), and RRC Inactive (RRC_INACTIVE). The RRC Idle and RRC Inactive states can be collectively referred to as the RRC Connected state. When the terminal device is in the RRC Connected state, communication connections have been established with both the RAN and the CN. When data arrives at the CN, it can be sent to the terminal device via the RAN, or the terminal device can send data to the RAN. When the terminal device is in the RRC Idle state, communication connections exist between the terminal device and both the RAN and the CN. When data needs to be transmitted, a communication link needs to be established between the terminal device and both the RAN and the CN. When the terminal device is in the RRC Inactive state, it indicates that the terminal device previously established communication connections with both the RAN and the CN, but the communication link between the terminal device and the RAN has been released. Although the communication link is released, the RAN stores the terminal device's context, and can quickly restore this communication link when data needs to be transmitted.

[0077] 2) Non-access stratum (NAS) and access stratum (AS): Depending on the destination of the communication connection with the terminal device, the protocol stack of the terminal device can be divided into NAS layer and AS layer. The NAS layer protocol implements the communication connection between the terminal device and the CN side, while the AS layer protocol implements the communication connection between the terminal device and the RAN side. Figure 2 This diagram illustrates a possible protocol stack structure for a terminal device. The AS layer comprises multiple protocol layers, such as the Radio Resource Control (RRC) layer, Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and Physical (PHY) layer. Correspondingly, the RAN side also has equivalent protocol layers to enable communication with the terminal device. The NAS layer enables communication between the terminal device and the CN side. Correspondingly, the CN side also has an equivalent NAS layer. It should be understood that the terminal device does not communicate directly with the CN side; NAS messages used for communication between the terminal device and the CN are typically encapsulated within AS messages used for communication between the terminal device and the RAN.

[0078] 3) Network Slice Identification: In a network, a network slice needs corresponding identification information for recognition. Currently, 3GPP SA2 defines Single Network Slice Selection Assistance Information (S-network slice SAI) to identify a network slice. Each S-network slice SAI consists of slice / service type (SST) and slice differentiator (SD), where SST is used to differentiate services and SD is used to differentiate tenants. One or more S-network slices (SI) constitute a network slice SAI. The network slice identification of each network slice can be represented by at least one of the following parameters:

[0079] 1. Network slice type information, for example, network slice type information can indicate network slice types such as enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), and massive machine type communication (mMTC). Optionally, the network slice type information can also indicate the end-to-end network slice type, including the network slice type from RAN to CN, or the RAN-side network slice type, or the CN-side network slice type.

[0080] 2. Business type information, which is related to specific businesses. For example, this business type information can indicate the characteristics of business such as video business, vehicle networking business, voice business, etc., or information about specific businesses.

[0081] 3. Tenant information, used to indicate customer information for creating or leasing the network slice, such as Tencent, State Grid, etc.;

[0082] 4. User group information, which indicates grouping information that groups users according to certain characteristics, such as user level;

[0083] 5. Slice group information, used to indicate that according to certain characteristics, for example, all network slices that the terminal device can access can be grouped into a slice group, or network slices can be grouped according to other criteria;

[0084] 6. Network slice instance information, used to indicate the instance identifier and characteristic information created for the network slice. For example, an identifier can be assigned to the network slice instance to indicate the network slice instance, or a new identifier can be mapped on the network slice instance identifier to associate the network slice instance. The receiver can identify the specific network slice instance indicated by the identifier based on the identifier.

[0085] 7. Dedicated Core Network (DCN) Identifier: This identifier is used to uniquely identify the dedicated core network in the LTE or eLTE system, such as the dedicated core network for the Internet of Things. Optionally, the DCN identifier can be mapped to the network slice identifier. The DCN identifier can be mapped to the network slice identifier, and vice versa.

[0086] When a terminal device switches on, it performs a Public Land Mobile Network (PLMN) selection to choose a network to provide service. The NAS entity of the terminal device can notify the AS entity of the selected PLMN for cell selection and reselection. Additionally, the terminal device can periodically search for PLMNs with higher priority. Alternatively, after leaving the coverage of a previously registered PLMN, the terminal device can automatically select a new PLMN or manually select one by receiving instructions from available PLMNs. Cell selection refers to the terminal device choosing a suitable cell from the selected PLMN to provide available service and monitoring the control channel of that cell after completing PLMN selection. This process is also known as the terminal device camping on a cell. Camping on a cell allows the terminal device to receive system information from the camped cell, access the control channel of the camped cell to establish or restore RRC connections, and receive network paging messages from the control channel of the camped cell, etc. Cell reselection refers to the process where, after a terminal device has been camped on a cell, it finds a more suitable cell based on cell reselection criteria, and then camps on that more suitable cell.

[0087] In NR (Network Node Network), different PLMNs can support different network slices, and different cells can also support different network slices. The inventors have discovered that in existing technologies, when a terminal device performs cell selection (reselection), the network slice support of the selected cell is not considered. This may result in the selected cell not supporting the network slice required by the terminal device, leading to incorrect cell selection and wasted network resources. Furthermore, when the terminal device selects a PLMN, it also fails to consider whether the selected PLMN supports the network slice subscribed to or desired by the terminal device, also leading to incorrect PLMN selection and wasted network resources. Therefore, this application provides a cell selection technical solution where the terminal device performs cell selection (reselection) based on the required network slice. Furthermore, this application also provides a technical solution where the terminal device selects a PLMN based on the subscribed or desired network slice.

[0088] This article provides the following specific implementation methods, which are described below in conjunction with... Figures 3 to 11 The technical solutions of this application will be described in detail with specific method embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. It should be noted that... Figures 3 to 11 This is a schematic flowchart illustrating an embodiment of the method of this application, showing the detailed communication steps or operations of the method. However, these steps or operations are merely examples, and other operations may be performed in the embodiments of this application. Figures 3 to 11 Variations of various operations within it. Furthermore, Figures 3 to 11 Each step in the process can be followed separately according to... Figures 3 to 11 The different orders presented may be executed, and it is possible that they are not intended to be executed. Figures 3 to 11 All operations within.

[0089] Figure 3 This is a schematic flowchart illustrating a cell selection method provided in an embodiment of this application. This method 300 is applied to a scenario where a terminal device residing in a current cell selects a new cell to camp on before initiating a service. In this scenario, the current cell does not support the network slice to which the service to be initiated by the terminal device belongs, and the terminal device needs to select a new cell to support the network slice to which the service to be initiated belongs; or the current cell supports only a portion of the network slice to which the service to be initiated belongs, and the terminal device needs to select a new cell to support more or all of the network slice to which the service to be initiated belongs. This selection of a new cell is also called cell reselection, meaning the terminal device reselects from its current cell to a new cell to camp on. Figure 3 The process includes the following steps:

[0090] S301. The terminal device determines the target network slice information.

[0091] When a terminal device is in an RRC disconnected state, it can camp on a single cell; this cell is called the camped cell. When the terminal device is about to initiate a service, it obtains the network slice information corresponding to that service (called the target service); this network slice is called the target network slice. It should be understood that the terminal device's impending service initiation can also be described as the service causing the terminal device's state to change from an RRC disconnected state to an RRC connected state. Typically, the terminal device needs to establish a PDU session with the network to carry the target service; therefore, the target network slice is also the network slice associated with the PDU session to which the target service belongs. It should be understood that a terminal device can initiate multiple services simultaneously; that is, the target service includes multiple services, and these services can belong to one PDU session or multiple PDU sessions. When these services belong to one PDU session, the target network slice corresponds to one network slice associated with that PDU session; when these services belong to multiple PDU sessions, the target network slice corresponds to one or more network slices associated with those multiple PDU sessions. In other words, the target service can be one or more services, and the target network slice can be one or more network slices. This application does not specifically limit the number of services included in the target service or the number of network slices included in the target network slice.

[0092] Specifically, the terminal device can determine the target network slice information in the following way: First, the NAS entity of the terminal device determines the target service and the target network slice; second, the NAS entity of the terminal device sends the network slice identifier of the target network slice (referred to as the target network slice identifier) ​​to the AS entity of the terminal device. Thus, the AS entity of the terminal device obtains the target network slice identifier. Optionally, the NAS entity sends the target network slice identifier along with the access category (AC) and access identity (AI) corresponding to the target service to the AS entity. It should be understood that when the target service includes multiple services, each service may have the same or different AC and AI; the target network slice identifier may contain the network slice identifiers of one or more network slices.

[0093] S302. The stationary cell sends network slice information to the terminal device. Correspondingly, the terminal device receives the network slice information from the stationary cell.

[0094] In this step, the residing cell sends network slice information to the terminal devices residing in the cell via cell broadcast.

[0095] In one possible implementation, the network slice information is used to indicate network slice information of the network slices supported by the stationary cell. For example, the network slice information includes network slice identifiers of one or more network slices supported by the stationary cell.

[0096] In another possible implementation, the network slice information is used to indicate the network slice information of the network slices supported by the stationary cell and the network slice information of the network slices supported by neighboring cells. For example, the network slice information includes network slice identifiers of one or more network slices supported by the stationary cell and network slice identifiers of one or more network slices supported by neighboring cells. It should be understood that neighboring cells correspond to one or more cells adjacent to the stationary cell.

[0097] S303, The terminal device determines to perform cell reselection.

[0098] In this step, the terminal device determines cell reselection based on the target network slice information and the network slice information of the camping cell and neighboring cells obtained from step S302 above.

[0099] For example, the terminal device determines cell reselection based on the target network slice identifier and the network slice identifier obtained from step S302. The network slice identifier of one or more network slices supported by the camped cell is called the camped cell network slice identifier. Correspondingly, any cell among the neighboring cells is defined as the first neighboring cell, and the identifier of the network slices supported by the first neighboring cell is called the first neighboring cell network slice identifier. It should be understood that the camped cell network slice identifier and the first neighboring cell network slice identifier may each contain one or more network slice identifiers. Corresponding to the two possible implementations of step S302 above, there are the following two methods in this step:

[0100] Community re-selection method 1:

[0101] This method corresponds to the case where the network slice information sent by the stationed cell only contains the stationed cell's network slice identifier.

[0102] When the network slice identifier of the camped cell does not include the target network slice identifier, the terminal device determines to perform cell reselection. In this case, since the camped cell does not support the target network slice, the terminal device needs to reselect a cell that supports the target network slice for camping.

[0103] Community re-selection method two:

[0104] This method corresponds to the case where the network slice information sent by the residing cell includes the residing cell's network slice identifier and one or more first neighboring cell network slice identifiers.

[0105] In one possible implementation, when the network slice identifier of the camping cell does not contain the target network slice identifier, and one or more first neighboring cell network slice identifiers contain the target network slice identifier, the terminal device determines to perform cell reselection. In this case, since the camping cell does not support the target network slice, the terminal device needs to reselect a cell that supports the target network slice for camping.

[0106] In another possible implementation, when the network slice identifier of the camping cell does not contain the target network slice identifier, and one or more first neighboring cell network slice identifiers contain part of the target network slice identifier, the terminal device determines to perform cell reselection. In this case, since the camping cell does not support the target network slice, the terminal device needs to reselect a cell that supports as many target network slices as possible for camping. For example, if the target network slice identifiers are network slice #1, network slice #2, and network slice #3, and the network slice identifiers of neighboring cell #1 are network slice #1, network slice #4, and network slice #5, the network slice identifiers of neighboring cell #3 are network slice #2, network slice #3, and network slice #5, and the network slice identifiers of neighboring cell #5 are network slice #3 and network slice #4, then the terminal device can reselect neighboring cell #3 for camping because neighboring cell #3 can support the most network slices in the target network slice.

[0107] In another possible implementation, when the network slice identifier of the camping cell contains a portion of the target network slice identifier, and one or more first neighboring cell network slice identifiers also contain a portion of the target network slice identifier, the terminal device determines to perform cell reselection. When a first neighboring cell network slice identifier contains more network slice identifiers than the camping cell network slice identifier, the terminal device can reselect a cell that supports as many target network slices as possible for camping. For example, when the first neighboring cell network slice identifier and the camping cell network slice identifier contain the same number of network slice identifiers as the target network slice identifier, and the first neighboring cell has better link quality, the terminal device can reselect a first neighboring cell that supports the same number of target network slices and has better link quality for camping. For example, the link quality of a cell can be measured by the RSRP value received by the terminal for that cell; a higher RSRP value indicates higher link quality, and vice versa.

[0108] In another possible implementation, although the network slice identifier of the stationing cell includes the target network slice identifier, the network slice identifier of the first neighboring cell also includes the target network slice identifier. If the first neighboring cell has better link quality, the terminal device can reselect a first neighboring cell that can support the target network slice and has better link quality for stationing.

[0109] S304. The terminal device performs cell reselection and camps on the target cell.

[0110] For the cell reselection method described above, the terminal device searches for neighboring cells of the target cell and selects one cell to camp on. For example, the terminal device reads the network slice identifiers of one or more first neighboring cells. If the network slice identifier of a first neighboring cell completely or to the maximum extent contains the target network slice identifier, then the first neighboring cell is called a candidate cell. When only one candidate cell exists, the terminal device camps on that candidate cell; when multiple candidate cells exist, the terminal device selects one or more candidate cells to camp on. The terminal device can select a cell from the candidate cells based on link quality, priority, or other preset criteria. The cell selected by the terminal device to camp on is called the target cell. It should be noted that for this cell reselection method, the terminal device can select the target cell to camp on using various methods in the prior art. This application does not specifically limit this method.

[0111] For the second cell reselection method described above, if the network slice identifier of the first neighboring cell completely or to the maximum extent contains the target network slice identifier, then the first neighboring cell is called a candidate cell. When only one candidate cell exists, the terminal device camps on that candidate cell; when multiple candidate cells exist, the terminal device selects one or more candidate cells to camp on. The terminal device can select a cell to camp on from the candidate cells based on link quality, priority, or other preset criteria. The cell that the terminal device selects to camp on is called the target cell.

[0112] After the terminal device completes cell reselection and selects to camp on the target cell, the terminal device synchronizes with the downlink signal of the target cell and listens to the control channel of the target cell, thereby camping on the target cell.

[0113] It should be noted that in step S302 above, the camping cell broadcasts network slice information to the terminal device in the RRC disconnected state. In an actual system, if the camping cell is the serving cell that the terminal device was connected to in the RRC_CONNECTED state before entering the RRC disconnected state, the serving cell can also send the network slice information to the terminal device via unicast (e.g., via RRC signaling) before the terminal device enters the RRC disconnected state. In this way, when the terminal device enters the RRC disconnected state and the camping cell is the serving cell, the terminal device can directly determine whether to perform cell reselection based on the network slice information it previously obtained from the serving cell.

[0114] Through the steps described above in this embodiment, when a terminal device in the RRC non-connected state is about to initiate a service, it can select to camp on a suitable cell that supports the service, so that the terminal device can quickly access the suitable cell when it subsequently initiates a service, effectively reducing the latency of service establishment and reducing signaling overhead.

[0115] Figure 4 This is a schematic flowchart illustrating a PLMN selection method provided in an embodiment of this application. This method 400 is applied to scenarios where a terminal device performs an initial PLMN selection upon power-on or periodically after registering with a network. In this scenario, the terminal device has subscribed to multiple PLMNs, and different PLMNs support different network slices. During the initial or periodic PLMN selection, the terminal device does not have service communication with the network, but it has a desired network slice, meaning it may subsequently initiate services belonging to that desired network slice. Therefore, the terminal device needs to select a PLMN that supports the desired network slice. Figure 4 The process includes the following steps:

[0116] S401. The terminal device obtains the network slice information supported by the contracted PLMN.

[0117] Optionally, if the terminal device has the capability to support multiple RAT standards, the terminal device also obtains network slice information supported by each RAT standard. In this case, the network slice information supported by the subscribed PLMN obtained by the terminal device also includes the network slice information supported by each RAT standard supported by the terminal device. In this case, the network slice information supported by the subscribed PLMN can also be referred to as the network slice information supported by multiple RATs under the subscribed PLMN.

[0118] The terminal device has signed contracts with multiple PLMNs. There are several ways for the terminal device to obtain network slice information supported by the contracted PLMNs. For example, in one possible implementation, the network slice information supported by the multiple PLMNs contracted by the terminal device is pre-configured, for example, it exists in the SIM card inserted into the terminal device, or it is pre-stored on the terminal device. Similarly, the network slice information supported by different RAT standards of the terminal device can also be pre-configured in the above manner. In another possible implementation, the network slice information supported by the multiple PLMNs contracted by the terminal device is stored on the terminal device based on the network-terminal device communication interface, and the network can update the network slice information stored on the terminal device through the communication interface. For example, an operator's network management system stores and updates the network slice information supported by the operator's PLMNs on the terminal device through the communication interface with the terminal device. Similarly, the network slice information supported by different RAT standards of the terminal device can also be stored and updated in the above manner.

[0119] For example, the terminal device obtains the network slice identifiers (also known as the network slice identifiers supported by the subscribed PLMN) of one or more network slices supported by each of the multiple subscribed PLMNs. The terminal device may further obtain the network slice identifiers (also known as the network slice identifiers supported by multiple RATs under the subscribed PLMN) of one or more network slices supported by each of its different RAT standards. It should be understood that the network slice identifiers supported by the subscribed PLMN and the network slice identifiers supported by multiple RATs under the subscribed PLMN may each contain one or more network slice identifiers.

[0120] For example, Table 1 provides a schematic of the network slice identifiers supported by the subscribed PLMN of a terminal device.

[0121] Table 1

[0122] PLMN List PLMN logo Network Slice Identifier List

[0123] The PLMN list contains multiple PLMN identifiers; each PLMN identifier corresponds to a network slice identifier list, which contains network slice identifiers for one or more network slices, and the network slice identifier list represents the network slices supported by the PLMN.

[0124] For example, Table 2 provides a schematic of the network slice identifiers supported by multiple RATs under a contracted PLMN of a terminal device.

[0125] Table 2

[0126] PLMN List PLMN logo RAT List >>RAT logo >>Network Slice Identifier List

[0127] The PLMN list contains multiple PLMN identifiers; each PLMN identifier corresponds to a RAT list; each RAT list contains one or more RAT identifiers, and each RAT identifier corresponds to a network slice identifier list, which contains network slice identifiers for one or more network slices. This network slice identifier list represents the network slices supported by the RAT. It should be understood that a RAT identifier can be the name of the RAT, an index, or other forms of characters or strings that can be used to identify a RAT; this document does not impose specific limitations on this.

[0128] S402, The terminal device determines the desired network slice.

[0129] Specifically, the NAS entity of the terminal device determines the desired network slice. The desired network slice indicates the network slice to which a service that the terminal device may subsequently initiate belongs. It should be understood that the desired network slice may contain one or more network slices. When one or more services that the terminal device may subsequently initiate belong to a single PDU session, the desired network slice is the network slice associated with that PDU session; when multiple services that the terminal device may subsequently initiate belong to multiple PDU sessions, the desired network slice is one or more network slices associated with those multiple PDU sessions.

[0130] S403. The terminal device selects a PLMN based on the desired network slice.

[0131] Depending on the RAT standard supported by the terminal device, there are multiple implementations for PLMN selection based on the desired network slice. For example, in one possible implementation, the terminal device supports only one RAT standard. In this case, the terminal device scans the radio frequency (RF) channels corresponding to that RAT standard to find multiple available PLMNs. On each carrier, the terminal device searches for the cell with the strongest signal and reads the system information of that cell to determine which PLMN(s) the cell belongs to. If the terminal device reads one or more PLMN identifiers in the cell with the strongest signal, the AS entity reports each read PLMN identifier to the NAS entity. For example, if the terminal device measures the RSRP value of the cell with the strongest signal to be greater than or equal to -110 dBm, the AS layer of the terminal device reports the read one or more PLMN identifiers to which the cell belongs to the NAS layer; if the terminal device measures the RSRP value of the cell with the strongest signal to be less than -110 dBm, the AS entity of the terminal device reports the read one or more PLMN identifiers to which the cell belongs and the corresponding RSRP value to the NAS entity.

[0132] After obtaining multiple PLMN identifiers (referred to as the PLMN identifier set) reported by the AS, the NAS entity of the terminal device selects a PLMN based on the desired network slice. Specifically, the terminal device combines the PLMN identifier set obtained by the NAS entity, the network slice identifiers supported by the subscribed PLMN obtained in step S401, and the desired network slice to select a PLMN.

[0133] For example, Table 3 shows the network slice identifiers supported by the PLMN subscribed to by the terminal device.

[0134] Table 3

[0135] PLMN List PLMN#1 >NS#1,NS#2,NS#3 PLMN#2 >NS#3,NS#5 PLMN#3 >NS#2,NS#7,NS#8

[0136] In this example, the terminal device has subscribed to PLMN#1, PLMN#2, and PLMN#3. PLMN#1 subscribed to by the terminal device supports NS#1, NS#2, and NS#3; PLMN#2 subscribed to by the terminal device supports NS#3 and NS#5; and PLMN#3 subscribed to by the terminal device supports NS#2, NS#7, and NS#8.

[0137] For example, suppose the desired network slice determined by the terminal device in step S402 is NS#3, and the multiple PLMN identifiers obtained by the terminal device through scanning the RF channel are PLMN#1, PLMN#3, PLMN#4, and PLMN#5. Then, in this step, the terminal device, combining Table 3 and the PLMN identifiers obtained through scanning the RF channel, can determine the potential PLMN set as {PLMN#1, PLMN#3}. In this example, the potential PLMN set is the intersection of the PLMN set subscribed to by the terminal device and the PLMN set obtained by the terminal device through scanning the RF channel. Further, since the desired network slice is NS#3, and PLMN#1 and PLMN#2 in Table 3 both support NS#3, but PLMN#2 does not belong to the potential PLMN set, the terminal device selects PLMN#1.

[0138] For example, suppose the desired network slice determined by the terminal device in step S402 above is NS#2, and the multiple PLMN identifiers obtained by the terminal device through scanning the RF channel are PLMN#1, PLMN#3, PLMN#4, and PLMN#5. Then, in this step, the terminal device, combining Table 3 and the PLMN identifiers obtained through scanning the RF channel, can determine the potential PLMN set as {PLMN#1, PLMN#3}. Similarly, in this example, the potential PLMN set is the intersection of the PLMN set subscribed to by the terminal device and the PLMN set obtained by the terminal device through scanning the RF channel. Further, since the desired network slice is NS#2, and both PLMN#1 and PLMN#3 in Table 3 support NS#2, the terminal device needs to select one PLMN from PLMN#1 and PLMN#3. The PLMN set {PLMN#1, PLMN#3} is also called the candidate PLMN set. In this example, the candidate PLMN set is a subset or the entire set of the potential PLMN set, which contains one or more PLMN identifiers in the potential PLMN set that support the desired network slice. The terminal device selects a PLMN from the candidate PLMN set. For example, if the terminal device reads PLMN#1 and PLMN#3 in different cells, it can select a PLMN based on the RSRP values ​​of each cell. For instance, if the RSRP value of the cell where PLMN#1 is read is less than the RSRP value of the cell where PLMN#3 is read, the terminal device selects PLMN#3. If the terminal device reads PLMN#1 and PLMN#3 in the same cell, it can select a PLMN based on preset criteria (such as operator priority). For instance, if the priority of PLMN#1 is higher than that of PLMN#3, the terminal device selects PLMN#1.

[0139] It should be noted that when multiple network slices are desired, the terminal device selects the PLMN that can fully support or maximize the support for the desired network slices. If multiple PLMNs that meet the above conditions exist, the terminal device can select a PLMN based on the RSRP value of the cell of the corresponding PLMN; or select a PLMN based on preset criteria (such as operator priority).

[0140] In another possible implementation, the terminal device supports multiple RAT standards. In this case, the terminal device can scan the RF channels corresponding to each RAT standard in descending order of RAT priority to find multiple available PLMNs; or, the terminal device can scan the RF channels corresponding to each RAT standard sequentially to find multiple available PLMNs; or, the terminal device can scan the RF channels corresponding to each RAT standard sequentially according to preset rules to find multiple available PLMNs. In the embodiments of this application, the terminal device can first consider which RAT standard(s) it supports support the desired network slice before performing RF channel scanning, thereby saving RF channel scanning time, saving resources and improving efficiency; the terminal device can also perform RF channel scanning on all supported RAT standards first in a traditional manner before considering the desired network slice, which has better backward compatibility.

[0141] The terminal device combines the PLMN identifier set obtained from the NAS entity, the network slice identifiers supported by multiple RATs under the subscribed PLMN obtained in step S401, and the desired network slice to select a PLMN. Specifically, this can be implemented in two ways:

[0142] PLMN Selection Method 1:

[0143] The terminal device first selects a set of candidate RATs from the network slice identifiers supported by multiple RATs under the PLMN it has signed up for, based on the desired network slice. Then, it performs an RF channel scan on the various RAT standards in the candidate RAT set to find a set of potential PLMNs. Next, the terminal device finds a set of candidate PLMNs from the set of potential PLMNs based on the RATs it supports and their ability to support the desired network slice. Finally, it selects a PLMN from the set of candidate PLMNs.

[0144] For example, Table 4 shows the network slice identifiers supported by multiple RATs under the PLMN subscribed to by the terminal device.

[0145] Table 4

[0146] PLMN List PLMN#1 >>RAT#1 >>NS#1,NS#2,NS#3 >>RAT#2 >>NS#2,NS#3 PLMN#2 >>RAT#2 >>NS#1,NS#2,NS#3 >>RAT#3 >>NS#1,NS#3,NS#4 >>RAT#5 >>NS#4,NS#5 PLMN#3 >>RAT#4 >>NS#1,NS#2,NS#3 >>RAT#6 >>NS#3,NS#4

[0147] Table 4 shows that the terminal device is subscribed to PLMN#1, PLMN#2, and PLMN#3, and supports six RAT standards: RAT#1, RAT#2, RAT#3, RAT#4, RAT#5, and RAT#6. Specifically, PLMN#1 subscribed to by the terminal device supports RAT#1 and RAT#2; RAT#1 supports NS#1, NS#2, and NS#3, and RAT#2 supports NS#2 and NS#3. PLMN#2 subscribed to by the terminal device supports RAT#2, RAT#3, and RAT#5; RAT#2 supports NS#1, NS#2, and NS#3, RAT#3 supports NS#1, NS#3, and NS#4, and RAT#5 supports NS#4 and NS#5. PLMN#3 subscribed to by the terminal device supports RAT#4 and RAT#6; RAT#4 supports NS#1, NS#2, and NS#3, and RAT#6 supports NS#3 and NS#4.

[0148] For example, assuming the desired network slice determined by the terminal device in step S402 above is NS#4, the terminal device selects a RAT standard that supports NS#4 from its six supported RAT standards, obtaining RAT#3, RAT#5, and RAT#6. Next, the terminal device can scan the RF channels of RAT#3, RAT#5, and RAT#6 respectively to obtain multiple PLMN identifiers. Assuming the terminal device obtains PLMN identifiers PLMN#1, PLMN#2, and PLMN#3 on the RF channel of RAT#3, PLMN#2, PLMN#4, and PLMN#5 on the RF channel of RAT#5, and PLMN#1, PLMN#2, and PLMN#4 on the RF channel of RAT#6, it obtains a potential PLMN set {PLMN#1, PLMN#2, PLMN#3, PLMN#4, PLMN#5}. Then, the terminal device further selects a candidate PLMN set from the potential PLMN set based on its supported RAT standards' ability to support the desired network slice. For example, PLMN#1, although it includes RAT#1 and RAT#2, does not support NS#4, therefore PLMN#1 is not a candidate PLMN set; PLMN#2 includes RAT#3 and RAT#5, which support NS#4, therefore PLMN#2 is a candidate PLMN set; PLMN#3 includes RAT#6, which supports NS#4, therefore PLMN#3 is a candidate PLMN set; PLMN#4 and PLMN#5, since the PLMN subscribed to by the terminal device does not include PLMN#4 and PLMN#5, PLMN#4 and PLMN#5 are also not candidates PLMN set. Thus, the candidate PLMN set is {PLMN#2, PLMN#3}. Furthermore, if the terminal device reads PLMN#2 and PLMN#3 from different cells, the terminal device can select the PLMN based on the RSRP values ​​of each cell. For example, if the RSRP value of the cell where PLMN#2 is read is less than the RSRP value of the cell where PLMN#3 is read, the terminal device selects PLMN#3. If the terminal device reads PLMN#2 and PLMN#3 from the same cell, the terminal device can select the PLMN based on preset criteria (such as operator priority). For example, if the priority of PLMN#2 is higher than that of PLMN#3, the terminal device selects PLMN#1. It should be understood that in this example, the terminal device can also scan the RF channels of RAT#3, RAT#5, and RAT#6 in a specific order according to RAT priority or preset criteria, or scan only some RAT standard RF channels. This application does not specifically limit this.

[0149] By using this method to select a PLMN, the terminal device first considers which RAT standard(s) it supports that support the desired network slice, and then performs an RF channel scan, thereby saving RF channel scanning time, saving resources and improving efficiency.

[0150] PLMN Selection Method Two:

[0151] The terminal device first performs an RF channel scan on the various RAT standards it supports in the traditional way to find a set of potential PLMNs, and then selects a PLMN based on the desired network slice.

[0152] For example, Table 4 is still used as the network slice identifier supported by multiple RATs under the PLMN subscribed by the terminal device, and it is assumed that the desired network slice determined by the terminal device in step S402 above is still NS#4. First, the terminal device scans the RF channels of each supported RAT standard (RAT#1, RAT#2, RAT#3, RAT#4, RAT#5, and RAT#6) to obtain multiple PLMN identifiers, forming a potential PLMN set {PLMN#1, PLMN#2, PLMN#3, PLMN#4, PLMN#5}. Then, the terminal device further selects a candidate PLMN set from the potential PLMN set based on the support capability of its supported RAT standards for the desired network slice. For example, PLMN#1 is not a candidate PLMN because neither its RAT#1 nor RAT#2 supports NS#4. PLMN#2 is a candidate PLMN because both its RAT#3 and RAT#5 support NS#4. PLMN#3 is a candidate PLMN because its RAT#6 supports NS#4. PLMN#4 and PLMN#5 are not candidates because the PLMNs subscribed to by the terminal devices do not include PLMN#4 and PLMN#5. Therefore, the candidate PLMN set is {PLMN#2, PLMN#3}. Furthermore, if the terminal device reads PLMN#2 and PLMN#3 from different cells, the terminal device can select the PLMN based on the RSRP values ​​of each cell. For example, if the RSRP value of the cell where PLMN#2 is read is less than the RSRP value of the cell where PLMN#3 is read, the terminal device selects PLMN#3. If the terminal device reads PLMN#2 and PLMN#3 from the same cell, the terminal device can select the PLMN based on preset criteria (such as operator priority). For example, if the priority of PLMN#2 is higher than that of PLMN#3, the terminal device selects PLMN#1. It should be understood that in this example, the terminal device can also scan the RF channels of RAT#3, RAT#5, and RAT#6 in a specific order according to RAT priority or preset criteria, or scan only some RAT standard RF channels. This application does not specifically limit this.

[0153] In this method of PLMN selection, the terminal device first performs an RF channel scan on all supported RAT standards in the traditional way to obtain a set of potential PLMNs, and then selects a PLMN based on the desired network slice, thus having better backward compatibility.

[0154] It should be noted that in both of the above methods, when the desired network slice consists of multiple network slices, the terminal device selects the PLMN that can fully support or maximize the support for the desired network slice. If multiple PLMNs that meet the above conditions exist, the terminal device can select a PLMN based on the RSRP value of the cell of the corresponding PLMN; or select a PLMN based on preset criteria (such as operator priority).

[0155] Through the steps described above in this embodiment, the terminal device in the RRC non-connected state can consider the network slice to which the service to be initiated may belong when selecting the PLMN. This enables the terminal device to select a suitable PLMN so that when the terminal device initiates a service later, it can quickly select a cell for access in the appropriate PLMN, effectively reducing the latency of service establishment and reducing signaling overhead.

[0156] After the terminal device completes the PLMN selection, it performs cell selection to choose a cell within that PLMN for camping. Alternatively, the terminal device periodically searches for higher-priority PLMNs and, after selecting a new PLMN, searches for a suitable cell for camping.

[0157] Figure 5 This is a schematic flowchart of another cell selection method provided in an embodiment of this application. This method 500 is applied to a scenario where, after a terminal device completes the selection of a PLMN, it performs cell selection to choose a cell under that PLMN for camping. Figure 5 The process includes the following steps:

[0158] S501, The terminal device determines the desired network slice.

[0159] Specifically, the NAS entity of the terminal device determines the desired network slice. The desired network slice indicates the network slice to which a service that the terminal device may subsequently initiate belongs. It should be understood that the desired network slice may contain one or more network slices. When one or more services that the terminal device may subsequently initiate belong to a single PDU session, the desired network slice is the network slice associated with that PDU session; when multiple services that the terminal device may subsequently initiate belong to multiple PDU sessions, the desired network slice is one or more network slices associated with those multiple PDU sessions.

[0160] S502, The terminal device selects a cell based on the desired network slice.

[0161] Terminal equipment in the aforementioned Figure 4The PLMN selection is completed after the implementation. In this step, the terminal device selects one of the cells in the selected PLMN to camp on based on the desired network slice.

[0162] In one possible implementation, when the PLMN selected by the terminal device contains multiple cells, and each cell supports the desired network slice, the terminal device can select one cell to camp on based on the cell's RSRP, priority, or preset criteria. When the terminal device supports multiple RAT standards, it can also select a suitable cell in one of the RATs to camp on based on the RAT's priority or preset criteria.

[0163] In another possible implementation, when the PLMN selected by the terminal device contains multiple cells, and each cell has different network slicing support capabilities, the terminal device selects a cell from these multiple cells that can support the desired network slice for camping. If multiple such cells exist, the terminal device can further select one for camping based on the cell's RSRP, priority, or preset criteria. When the terminal device supports multiple RAT standards, it can also select a suitable cell from the RAT for camping based on the RAT's priority or preset criteria.

[0164] Through the steps described above in this embodiment, the terminal device in the RRC non-connected state can consider the network slice to which the service to be initiated may belong when selecting a cell. This enables the terminal device to select a suitable cell to camp on, so that the terminal device can quickly access the appropriate cell when initiating a service later, effectively reducing the latency of service establishment and reducing signaling overhead.

[0165] Corresponding to Figure 5 The following is a flowchart of the community selection method. Figures 6 to 8 It provides different ways for the NAS and AS entities within the terminal device to interact and achieve cell selection.

[0166] Figure 6 A flowchart illustrating another cell selection method is provided. This method 600 is applied to scenarios where the NAS entity of a terminal device determines the desired network slice as a single network slice. Figure 6 The process includes the following steps:

[0167] S601, the NAS entity sends the network slice identifier of a desired network slice to the AS entity. Correspondingly, the AS entity receives the network slice identifier of the desired network slice from the NAS entity.

[0168] In this step, the NAS entity sends its determined desired network slice identifier to the AS entity. The desired network slice is a network slice, therefore the desired network slice identifier corresponds to a network slice identifier.

[0169] S602 and AS entities listen for cell broadcast messages.

[0170] After completing the PLMN selection, in this step, the terminal device listens for broadcast messages from each cell in one or more cells of the selected PLMN. These broadcast messages contain information about the network slices supported by the cell sending the broadcast message, such as the network slice identifiers of one or more network slices supported by the cell.

[0171] S603, AS entities select cells based on the desired network slice identifier.

[0172] In this step, the AS entity selects a cell based on the network slice identifier of the desired network slice obtained in step S601 above and the network slice identifiers supported by one or more cells obtained in step S602 above.

[0173] In one possible implementation, if the AS entity obtains in step S602 that only one cell supports a network slice identifier that contains the desired network slice identifier, then the AS entity selects that cell to camp on.

[0174] In another possible implementation, if the AS entity obtains the network slice identifiers supported by multiple cells in step S602 above, including the desired network slice identifier, then the AS entity can select one of the multiple cells to camp on based on the cell RSRP, priority, or preset criteria.

[0175] Through the steps described above in this embodiment, the AS entity of the terminal device in the RRC non-connected state can consider a network slice to which a service that may be initiated later belongs when selecting a cell. This enables the AS entity to select a suitable cell to camp on, so that the NAS entity can quickly access the appropriate cell when initiating services later, effectively reducing the latency of service establishment and reducing signaling overhead.

[0176] Figure 7 A flowchart illustrating another cell selection method is provided. This method 700 is applied to scenarios where the NAS entity of a terminal device selects the cell to reside in for multiple network slices. Figure 7 The process includes the following steps:

[0177] S701, the NAS entity sends network slice identifiers of multiple first network slices to the AS entity. Correspondingly, the AS entity receives the network slice identifiers of multiple first network slices from the NAS entity.

[0178] In this step, the NAS entity sends multiple first network slice identifiers to the AS entity. These multiple first network slice identifiers are determined by the NAS entity, where each first network slice identifier is an identifier of a network slice subscribed to by the terminal device with the selected PLMN. The NAS entity may send the identifiers of some or all of the network slices subscribed to by the terminal device with the selected PLMN to the AS layer. Optionally, these multiple first network slices are desired network slices with multiple network slices determined by the NAS entity.

[0179] S702 and AS entities listen for cell broadcast messages.

[0180] After completing the PLMN selection, in this step, the terminal device listens for broadcast messages from each cell in one or more cells of the selected PLMN. These broadcast messages contain information about the network slices supported by the cell sending the broadcast message, such as the network slice identifiers of one or more network slices supported by the cell.

[0181] S703 and AS entities select cells based on multiple first network slice identifiers.

[0182] In this step, the AS entity selects a cell based on the network slice identifiers of the multiple first network slices obtained in step S701 above and the network slice identifiers supported by one or more cells obtained in step S702 above.

[0183] In one possible implementation, if the network slice identifiers supported by each cell obtained by the AS entity in step S702 contain varying degrees of the aforementioned multiple first network slice identifiers, then the AS entity selects one of these cells to camp on. For example, some cells do not support first network slices, some cells support some first network slices, and some cells support all first network slices. The AS entity selects the cell that supports the most first network slices to camp on; or the AS entity selects a specific cell to camp on based on a preset criterion, for example, this specific cell may not support the most first network slices, but its RSRP value is the highest.

[0184] In another possible implementation, if the network slice identifiers supported by each cell obtained by the AS entity in step S702 above contain the aforementioned multiple first network slice identifiers to the same extent, then the AS entity can select one cell from the multiple cells for camping based on the cell RSRP, priority, or preset criteria.

[0185] Through the steps described above in this embodiment, the AS entity of the terminal device in the RRC non-connected state can consider multiple network slices belonging to different services when selecting cells, so that the AS entity can select a suitable cell to camp on, and the NAS entity can quickly access the appropriate cell when initiating services later, effectively reducing the latency of service establishment and reducing signaling overhead.

[0186] Figure 8 A flowchart illustrating another cell selection method is provided. This method 800 is applied to scenarios where the NAS entity of the terminal device provides multiple network slices, and the AS entity determines the desired network slice. Figure 8 The process includes the following steps:

[0187] S801, the NAS entity sends network slice identifiers of multiple first network slices to the AS entity. Correspondingly, the AS entity receives the network slice identifiers of multiple first network slices from the NAS entity.

[0188] In this step, the NAS entity sends multiple first network slice identifiers to the AS entity. These multiple first network slice identifiers are determined by the NAS entity, where each first network slice identifier is an identifier of a network slice subscribed to by the terminal device with the selected PLMN. The NAS entity may send the identifiers of some or all of the network slices subscribed to by the terminal device with the selected PLMN to the AS layer. Optionally, these multiple first network slices are desired network slices with multiple network slices determined by the NAS entity.

[0189] S802, AS entity determines the desired network slice.

[0190] In this step, the AS entity determines the desired network slice from the plurality of first network slices obtained in step S801 above. The desired network slice is used to indicate the network slice to which a service that the terminal device may subsequently initiate belongs. It should be understood that the desired network slice may contain one or more network slices. When one or more services that the terminal device may subsequently initiate belong to a single PDU session, the desired network slice is a network slice associated with that PDU session; when multiple services that the terminal device may subsequently initiate belong to multiple PDU sessions respectively, the desired network slice is one or more network slices associated with those multiple PDU sessions.

[0191] S803 and AS entities listen for cell broadcast messages.

[0192] After completing the PLMN selection, in this step, the terminal device listens for broadcast messages from each cell in one or more cells of the selected PLMN. These broadcast messages contain information about the network slices supported by the cell sending the broadcast message, such as the network slice identifiers of one or more network slices supported by the cell.

[0193] S804, AS entity selects cell based on desired network slice identifier.

[0194] In this step, the AS entity selects a cell based on the network slice identifier of the desired network slice determined in step S802 above and the network slice identifiers supported by one or more cells obtained in step S803 above.

[0195] In one possible implementation, when the desired network slice identifier contains a network slice identifier, the AS entity determines in step S803 above that only one cell supports a network slice identifier containing the desired network slice identifier, and then the AS entity selects that cell to camp on.

[0196] In another possible implementation, when the desired network slice identifier contains a network slice identifier, the AS entity obtains in step S803 that the network slice identifiers supported by multiple cells contain the desired network slice identifier. Then, the AS entity can select one cell from the multiple cells for camping based on the cell RSRP, priority, or preset criteria.

[0197] In another possible implementation, when the desired network slice identifier includes multiple network slice identifiers, and the network slice identifiers supported by each cell obtained by the AS entity in step S803 above contain the desired network slice identifier to varying degrees, the AS entity selects one of these cells to camp on. For example, some cells do not support the desired network slice, some cells support some of the desired network slices, and some cells support all of the desired network slices. The AS entity selects the cell that supports the most desired network slices to camp on; or the AS entity selects a specific cell to camp on according to a preset criterion, for example, this specific cell may not support the most desired network slices, but its RSRP value is the highest.

[0198] In another possible implementation, when the desired network slice identifier includes multiple network slice identifiers, and the network slice identifiers supported by each cell obtained by the AS entity in step S803 above all contain the desired network slice identifier to the same extent, then the AS entity can select one cell from the multiple cells for camping based on the cell RSRP, priority, or preset criteria.

[0199] Through the steps described above in this embodiment, the AS entity of the terminal device in the RRC non-connected state can consider the network slice to which one or more services that may be initiated later belong when selecting a cell. This enables the AS entity to select a suitable cell to camp on, so that the NAS entity can quickly access the appropriate cell when initiating services later, effectively reducing the latency of service establishment and reducing signaling overhead.

[0200] After the terminal device completes PLMN and cell selection, it camps on a cell. Subsequently, the terminal device can also perform cell reselection based on the desired network slice, selecting a new cell to camp on. Figure 3 The difference in the cell reselection scenario described in the embodiments is that the terminal device is not about to initiate a service at this time. That is to say, the terminal device will not change from the RRC disconnected state to the RRC connected state. The terminal device will continue to be in the RRC disconnected state, but the terminal device may subsequently initiate a service belonging to the desired network slice.

[0201] Figure 9 A flowchart illustrating another cell selection method is provided. This method 900 is applied to a scenario where the NAS entity of a terminal device determines that the desired network slice is a network slice and reselects a new cell to camp on. In this scenario, the current cell does not support the terminal device's desired network slice, and the terminal device needs to camp on a new cell to support the desired network slice. Figure 9 The process includes the following steps:

[0202] S901, the NAS entity of the terminal device sends the network slice identifier of a desired network slice to the AS entity. Correspondingly, the AS entity receives the network slice identifier of the desired network slice from the NAS entity.

[0203] In this step, the NAS entity sends its determined desired network slice identifier to the AS entity. The desired network slice is a network slice, therefore the desired network slice identifier corresponds to a network slice identifier.

[0204] S902, the stationary cell sends AS information to the terminal device. Correspondingly, the terminal device receives network slice information from the stationary cell.

[0205] Specifically, the AS entity of the terminal device receives network slice information from the stationed cell.

[0206] In this step, the stationary cell sends network slice information to the terminal devices residing in the cell via cell broadcast. In one possible implementation, this network slice information indicates the network slices supported by the stationary cell. For example, the network slice information includes network slice identifiers of one or more network slices supported by the stationary cell.

[0207] In another possible implementation, the network slice information is used to indicate the network slice information of the network slices supported by the stationary cell and the network slice information of the network slices supported by neighboring cells. For example, the network slice information includes network slice identifiers of one or more network slices supported by the stationary cell and network slice identifiers of one or more network slices supported by neighboring cells. It should be understood that neighboring cells correspond to one or more cells adjacent to the stationary cell.

[0208] S903, The terminal device determines to perform cell reselection.

[0209] Specifically, the AS entity of the terminal device determines the cell reselection based on the desired network slice identifier.

[0210] S904, The terminal device performs cell reselection and camps on the target cell.

[0211] Specifically, the AS entity of the terminal device performs cell reselection based on the desired network slice identifier and camps on the target cell.

[0212] Steps S903 and S904 described above are similar to steps S303 and S304 in the aforementioned embodiments, and will not be repeated here.

[0213] It should be noted that in step S902 above, the camping cell broadcasts network slice information to the terminal device in the RRC disconnected state. In an actual system, if the camping cell is the serving cell that the terminal device was connected to in the RRC connected state before entering the RRC disconnected state, the serving cell can also send the network slice information to the terminal device via unicast (e.g., via RRC signaling) before the terminal device enters the RRC disconnected state. In this way, when the terminal device enters the RRC disconnected state and the camping cell is the serving cell, the terminal device can directly determine whether to perform cell reselection based on the network slice information it previously obtained from the serving cell.

[0214] Through the steps described above in this embodiment, the terminal device enables the AS entity to choose to reside in a suitable cell that supports the network slice when the terminal device in the RRC non-connected state may subsequently initiate a service belonging to a network slice. This allows the terminal device to quickly access the appropriate cell when initiating a service, effectively reducing the latency of service establishment and reducing signaling overhead.

[0215] Figure 10A flowchart illustrating another cell selection method is provided. This method 1000 is applied to a scenario where the NAS entity of a terminal device reselects a new cell to camp on for multiple network slices. In this scenario, the camped cell does not support the multiple network slices of the terminal device, and the terminal device needs to camp on a new cell to support the multiple network slices; or the camped cell partially supports the multiple network slices of the terminal device, and the terminal device needs to camp on a new cell to support more or all of the multiple network slices. The process described in Figure 1000 includes the following steps:

[0216] S1001, the NAS entity of the terminal device sends network slice identifiers of multiple first network slices to the AS entity. Correspondingly, the AS entity receives the network slice identifiers of multiple first network slices from the NAS entity.

[0217] Step S1001 is similar to step S701 in the previous embodiment, and will not be repeated here.

[0218] S1002, The stationary cell sends AS information to the terminal device. Correspondingly, the terminal device receives network slice information from the stationary cell.

[0219] Specifically, the AS entity of the terminal device receives network slice information from the stationed cell.

[0220] S1003, The terminal device determines to perform cell reselection.

[0221] Specifically, the AS entity of the terminal device determines cell reselection based on multiple first network slice identifiers.

[0222] S1004. The terminal device performs cell reselection and camps on the target cell.

[0223] Specifically, the AS entity of the terminal device performs cell reselection based on multiple first network slice identifiers and camps on the target cell.

[0224] The steps S1002 to S1004 described above are similar to steps S902 to S904 in the aforementioned embodiments, and will not be repeated here.

[0225] It should be noted that in step S1002 above, the camping cell broadcasts network slice information to the terminal device in the RRC disconnected state. In an actual system, if the camping cell is the serving cell that the terminal device was connected to in the RRC_CONNECTED state before entering the RRC disconnected state, the serving cell can also send the network slice information to the terminal device via unicast (e.g., via RRC signaling) before the terminal device enters the RRC disconnected state. In this way, when the terminal device enters the RRC disconnected state and the camping cell is the serving cell, the terminal device can directly determine whether to perform cell reselection based on the network slice information it previously obtained from the serving cell.

[0226] Through the steps described above in this embodiment, when a terminal device supporting multiple network slices is in an RRC-disconnected state, or when a terminal device in an RRC-disconnected state may subsequently initiate services belonging to multiple network slices, the AS entity can select to reside in a suitable cell that supports the multiple network slices. This enables the terminal device to quickly access the appropriate cell when initiating services, effectively reducing service establishment latency and signaling overhead.

[0227] Figure 11 A flowchart illustrating another cell selection method is provided. This method 1100 is applied to a scenario where the NAS entity of a terminal device provides multiple network slices, and the AS entity determines the desired network slice. In this scenario, the currently used cell does not support the terminal device's desired network slice, and the terminal device needs to camp on a new cell to support the desired network slice; or the currently used cell supports part of the terminal device's desired network slice, and the terminal device needs to camp on a new cell to support more or all of the desired network slice. Figure 11 The process includes the following steps:

[0228] S1101, the NAS entity of the terminal device sends network slice identifiers of multiple first network slices to the AS entity. Correspondingly, the AS entity receives the network slice identifiers of multiple first network slices from the NAS entity.

[0229] S1102, The AS entity of the terminal device determines the desired network slice.

[0230] The steps S1101 and S1102 described above are similar to steps S801 and S802 in the aforementioned embodiments, and will not be repeated here.

[0231] S1103. The stationary cell sends AS information to the terminal device. Correspondingly, the terminal device receives network slice information from the stationary cell.

[0232] Step S1103 is similar to step S902 in the previous embodiment, and will not be repeated here.

[0233] S1104, The terminal device determines to perform cell reselection.

[0234] Specifically, the AS entity of the terminal device determines to perform cell reselection.

[0235] S1105, The terminal device performs cell reselection and camps on the target cell.

[0236] Specifically, the AS entity of the terminal device performs cell reselection and camps on the target cell.

[0237] The steps S1104 and S1105 described above are similar to steps S303 and S304 in the aforementioned embodiments, and will not be repeated here.

[0238] It should be noted that in step S1103 above, the camping cell broadcasts network slice information to the terminal device in the RRC disconnected state. In an actual system, if the camping cell is the serving cell that the terminal device was connected to in the RRC_CONNECTED state before entering the RRC disconnected state, the serving cell can also send the network slice information to the terminal device via unicast (e.g., via RRC signaling) before the terminal device enters the RRC disconnected state. In this way, when the terminal device enters the RRC disconnected state and the camping cell is the serving cell, the terminal device can directly determine whether to perform cell reselection based on the network slice information it previously obtained from the serving cell.

[0239] Through the steps described above in this embodiment, when a terminal device supporting multiple network slices is in an RRC disconnected state and the terminal device may subsequently initiate a service belonging to a network slice, the AS entity can choose to camp on a suitable cell that supports the network slice. This enables the terminal device to quickly access the appropriate cell when initiating a service, effectively reducing service establishment latency and signaling overhead.

[0240] It should be noted that, in Figures 9 to 11 In the illustrated embodiment, although the terminal device is in the RRC disconnected state, the core network side may store the context information of the PDU session conducted by the terminal device before entering the RRC disconnected state.

[0241] When the core network side stores the context information of a PDU session of a terminal device, Figures 9 to 11 In the illustrated embodiment, the NAS entity sends the network slice associated with the PDU session to the AS as the desired network slice, or the AS entity stores the network slice associated with the PDU session and identifies it as the desired network slice. The AS entity performs cell reselection based on the desired network slice.

[0242] When the core network side stores the context information of multiple PDU sessions of the terminal device, Figures 9 to 11 In the illustrated embodiments, correspondingly, in one possible implementation, the NAS entity stores the network slices associated with the multiple PDU sessions. The NAS entity determines one network slice as the desired network slice from the multiple network slices associated with the multiple PDU sessions and sends the desired network slice identifier to the AS entity. The AS entity performs cell reselection based on the desired network slice identifier. In another possible implementation, the NAS entity stores the network slices associated with the multiple PDU sessions and sends the network slice identifiers of the multiple network slices associated with the multiple PDU sessions to the AS entity. The AS entity determines one network slice identifier as the desired network slice identifier from these network slice identifiers and performs cell reselection based on the desired network slice identifier. In yet another possible implementation, the NAS entity stores the network slices associated with the multiple PDU sessions and sends the network slice identifiers of the multiple network slices associated with the multiple PDU sessions to the AS entity. The AS entity determines from the cell broadcast message which cell can be reselected to camp on to maximize support for the multiple network slices. In another possible implementation, the AS entity stores the network slices associated with the multiple PDU sessions. The AS entity determines one network slice as the desired network slice from among the multiple network slices associated with the multiple PDU sessions, and performs cell reselection based on the desired network slice identifier. In yet another possible implementation, the AS entity stores the network slices associated with the multiple PDU sessions, and the AS entity determines from the cell broadcast message which cell to reselect and camp on to the cell that best supports the multiple network slices.

[0243] It should be noted that a terminal device in an RRC disconnected state may move, causing it to move from one registration area to another. In this case, the terminal device needs to initiate a registration area update procedure to obtain a newly registered network slice. This newly registered network slice serves as a candidate network slice during the aforementioned cell reselection; that is, the target network slice or desired network slice considered by the terminal device when initiating cell reselection is one or more of these candidate network slices.

[0244] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)). Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this patent application.

[0245] The above text combined Figures 3 to 11 The method embodiments of this application have been described in detail below, in conjunction with... Figures 12 to 14 This application describes in detail the apparatus embodiments. It should be understood that the apparatus embodiments correspond to the method embodiments, and similar descriptions can be found in the method embodiments. It is worth noting that the apparatus embodiments can be used in conjunction with the above methods, or they can be used independently.

[0246] Figure 12 A schematic block diagram of a terminal device 1200 according to an embodiment of this application is shown. The terminal device 1200 may correspond to (for example, may be configured in or be itself) the terminal device described in method 300, or the terminal device described in method 400, or the terminal device described in method 500, or the terminal device described in method 600, or the terminal device described in method 700, or the terminal device described in method 800, or the terminal device described in method 900, or the terminal device described in method 1000, or the terminal device described in method 1100, or the terminal device described in other embodiments.

[0247] The terminal device 1200 may include a communication unit 1201 and a processing unit 1202. The communication unit 1201 may include a sending unit and / or a receiving unit. The sending unit implements a sending function, and the receiving unit implements a receiving function. The communication unit 1201 can implement both sending and / or receiving functions. The communication unit can also be described as a transceiver unit. The terminal device 1200 may further include a storage unit 1203 for storing programs or data to be executed by the processing unit 1202, or storing information received and / or sent through the communication unit 1201. The terminal device 1200 may be a terminal device, a device within another device, or a device compatible with a terminal device.

[0248] Each unit in the terminal device 1200 is used to execute the actions or processes performed by the terminal device described in method 300, method 400, method 500, method 600, method 700, method 800, method 900, method 1000, method 1100, or other embodiments of the terminal device described therein. Detailed descriptions are omitted here to avoid redundancy.

[0249] Figure 13 A schematic block diagram of a terminal device 1300 according to an embodiment of this application is shown. The terminal device 1300 may correspond to (for example, may be configured in or be itself) the terminal device described in method 300, or the terminal device described in method 400, or the terminal device described in method 500, or the terminal device described in method 600, or the terminal device described in method 700, or the terminal device described in method 800, or the terminal device described in method 900, or the terminal device described in method 1000, or the terminal device described in method 1100, or the terminal device described in other embodiments.

[0250] The terminal device 1300 may include one or more processors 1301. The processor 1301 may be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the terminal device, execute computer programs, and process data from those programs.

[0251] Terminal device 1300 may also include transceiver 1302 and antenna 1303. Transceiver 1302 may be referred to as transceiver unit, transceiver, or transceiver circuit, etc., and is used to implement transceiver functions. Transceiver 1302 may include receiver and transmitter. Receiver may be referred to as receiver or receiving circuit, etc., and is used to implement receiving function; transmitter may be referred to as transmitter or transmitting circuit, etc., and is used to implement transmitting function.

[0252] Optionally, the terminal device 1300 may include one or more memories 1304, on which a computer program 1305 may be stored. This computer program can be run on the terminal device 1300, causing the terminal device 1300 to perform the methods described in the above method embodiments. Optionally, the memory 1304 may also store data. The terminal device 1300 and the memory 1304 may be configured separately or integrated together.

[0253] In one possible implementation, the processor 1301 may include a transceiver for implementing receive and transmit functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit may be used for reading and writing code / data, or it may be used for transmitting or relaying signals.

[0254] In one possible implementation, processor 1301 may store computer program 1306, which runs on processor 1301 and enables terminal device 1300 to perform the methods described in the above method embodiments. Computer program 1306 may be embedded in processor 1301; in this case, processor 1301 may be implemented in hardware.

[0255] In one possible implementation, the terminal device 1300 may include circuitry capable of performing the transmitting, receiving, or communication functions described in the foregoing method embodiments. The processor and transceiver described in this application can be implemented on integrated circuits (ICs), analog ICs, radio frequency integrated circuits (RFICs), mixed-signal ICs, application-specific integrated circuits (ASICs), printed circuit boards (PCBs), electronic devices, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal oxide semiconductors (CMOS), n-metal-oxide-semiconductor (NMOS), positive-channel metal oxide semiconductors (PMOS), bipolar junction transistors (BJTs), bipolar CMOS (BiCMOS), silicon germanium (SiGe), gallium arsenide (GaAs), etc.

[0256] It should be understood that processor 1301 can be a central processing unit (CPU), a network processor (NP), a hardware chip, or any combination thereof. The aforementioned hardware chip can be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The aforementioned PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof. Memory 1304 can be volatile memory, such as random-access memory (RAM); it can also be non-volatile memory, such as read-only memory (ROM), flash memory, hard disk drive (HDD), or solid-state drive (SSD); or it can be a combination of the above types of memory.

[0257] The processors 1301 and transceivers 1302 in the terminal device 1300 are respectively used to execute the actions or processing procedures performed by the terminal device described in method 300, method 400, method 500, method 600, method 700, method 800, method 900, method 1000, method 1100, or other embodiments of the terminal device described therein. Detailed descriptions are omitted here to avoid redundancy.

[0258] The structure of terminal device 1300 is not subject to Figure 13 The terminal device 1300 may be a standalone device or part of a larger device. For example, the terminal device 1300 may be:

[0259] (1) Independent integrated circuit IC, or chip, or chip system or subsystem;

[0260] (2) A collection of one or more ICs, optionally including storage components for storing data and computer programs;

[0261] (3) ASIC, such as modem;

[0262] (4) Modules that can be embedded in other devices;

[0263] (5) Receivers, terminals, smart terminals, cellular phones, wireless devices, handheld devices, mobile units, vehicle-mounted devices, network devices, cloud devices, artificial intelligence devices, etc.

[0264] (6) Others, etc.

[0265] For cases where the terminal device 1300 can be a chip or a chip system, please refer to [link / reference]. Figure 14 The diagram shows the structure of chip 1400. Figure 14 The chip 1400 shown includes logic circuitry 1401 and input / output interface 1402. The input / output interface 1402 is used to communicate with modules outside the chip 1400. The logic circuitry 1401 is used to run computer programs or instructions to implement the functions of any of the above method embodiments. The number of input / output interfaces 1402 can be multiple.

[0266] Optionally, chip 1400 may also include memory 1403 for storing necessary computer programs (or instructions) and data.

[0267] The logic circuit 1401 and input / output interface 1402 in chip 1400 are respectively used to execute the various actions or processes performed by the terminal device described in method 300, method 400, method 500, method 600, method 700, method 800, method 900, method 1000, method 1100, or the terminal device described in other embodiments. Detailed descriptions are omitted here to avoid redundancy.

[0268] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication coupling shown or discussed may be through some interfaces; the indirect coupling or communication coupling of apparatuses or units may be electrical, mechanical, or other forms.

[0269] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0270] In addition, the functional units in the various embodiments of this patent application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0271] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this patent application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and contains several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this patent application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0272] The above are merely specific embodiments of this patent application, but the scope of protection of this patent application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this patent application should be included within the scope of protection of this patent application. Therefore, the scope of protection of this patent application shall be determined by the scope of the claims.

Claims

1. A method for selecting a cell, characterized in that, include: The terminal device determines first network slice information, which includes the identifier of at least one network slice. The first network slice information is used to indicate the identifier of at least one network slice to which at least one service to be initiated by the terminal device belongs. The terminal device receives second network slice information sent from the stationary cell. The second network slice information includes the identifier of at least one network slice supported by the stationary cell and the identifier of at least one network slice supported by at least one neighboring cell of the stationary cell. as well as The terminal device performs cell reselection based on the first network slice information and the second network slice information; Cell reselection is performed based on the first network slice information and the second network slice information, including: When the network slice identifier portion of the stationed cell includes a first network slice identifier, and the number of network slices at the intersection of at least one neighboring cell network slice identifier and the first network slice identifier is greater than the number of network slices at the intersection of the stationed cell network slice identifier and the first network slice identifier, the terminal device performs cell reselection. The cell reselection includes: among the at least one neighboring cell, selecting a neighboring cell whose number of network slices at the intersection of the neighboring cell network slice identifier and the first network slice identifier is greater than the number of network slices at the intersection of the stationed cell network slice identifier and the first network slice identifier for stationing. The resident cell network slice identifier is used to indicate the identifier of at least one network slice supported by the resident cell, the first network slice identifier is used to indicate the identifier of at least one network slice included in the first network slice information, and the neighbor cell network slice identifier is used to indicate the identifier of at least one network slice supported by at least one neighbor cell of the resident cell.

2. The method according to claim 1, characterized in that, The terminal device performs cell reselection based on the first network slice information and the second network slice information, and further includes: If the network slice identifier of the stationed cell does not include the first network slice identifier, the terminal device performs cell reselection.

3. The method according to claim 1, characterized in that, The terminal device performs cell reselection based on the first network slice information and the second network slice information, and further includes: If the network slice identifier of the stationed cell does not contain the first network slice identifier, and at least one of the neighboring cell network slice identifiers partially or completely contains the first network slice identifier, the terminal device performs cell reselection.

4. The method according to claim 1, characterized in that, The terminal device performs cell reselection based on the first network slice information and the second network slice information, and further includes: The terminal device performs cell reselection when the number of network slices at the intersection of the stationary cell network slice identifier and the first network slice identifier is equal to the number of network slices at the intersection of at least one neighboring cell network slice identifier and the first network slice identifier, and the link quality of the stationary cell is lower than the link quality of the at least one neighboring cell.

5. The method according to claim 1 or 3, characterized in that, In the at least one neighboring cell, selecting a neighboring cell whose number of network slices intersecting the neighboring cell network slice identifier and the first network slice identifier is greater than the number of network slices intersecting the stationing cell network slice identifier and the first network slice identifier for stationing includes: the terminal device selecting the neighboring cell with the largest number of network slices intersecting the neighboring cell network slice identifier and the first network slice identifier from the at least one neighboring cell for stationing.

6. The method according to claim 5, characterized in that, Selecting the neighboring cell with the largest number of network slices at the intersection of the neighboring cell network slice identifier and the first network slice identifier for residency in the at least one neighboring cell includes: When the number of network slices where the intersection of multiple neighboring network slice identifiers and the first network slice identifier is maximized, The terminal device selects the neighboring cell with the highest link quality from the multiple neighboring cells to stay in; or, the terminal device selects the neighboring cell with the highest priority from the multiple neighboring cells to stay in.

7. A terminal device, characterized in that, The terminal device includes a processing unit and a communication unit, wherein... The processing unit is configured to determine first network slice information, the first network slice information containing the identifier of at least one network slice, and the first network slice information is used to indicate the identifier of at least one network slice to which at least one service to be initiated by the terminal device belongs; The communication unit is communicatively coupled to the processing unit and is used to receive second network slice information sent from the stationary cell. The second network slice information includes the identifier of at least one network slice supported by the stationary cell and the identifier of at least one network slice supported by at least one neighboring cell of the stationary cell. The processing unit is further configured to perform cell reselection based on the first network slice information and the second network slice information. The cell reselection based on the first network slice information and the second network slice information includes: performing cell reselection when the network slice identifier portion of the stationed cell contains a first network slice identifier, and the number of network slices at the intersection of at least one neighboring cell's network slice identifier and the first network slice identifier is greater than the number of network slices at the intersection of the stationed cell's network slice identifier and the first network slice identifier. The cell reselection includes: selecting, among the at least one neighboring cell, a neighboring cell whose number of network slices at the intersection of the neighboring cell's network slice identifier and the first network slice identifier is greater than the number of network slices at the intersection of the stationed cell's network slice identifier and the first network slice identifier for stationing. The resident cell network slice identifier is used to indicate the identifier of at least one network slice supported by the resident cell, the first network slice identifier is used to indicate the identifier of at least one network slice included in the first network slice information, and the neighbor cell network slice identifier is used to indicate the identifier of at least one network slice supported by at least one neighbor cell of the resident cell.

8. The terminal device according to claim 7, characterized in that, The processing unit performs cell reselection based on the first network slice information and the second network slice information, including: If the network slice identifier of the stationed cell does not include the first network slice identifier, the processing unit performs cell reselection.

9. The terminal device according to claim 7, characterized in that, The processing unit performs cell reselection based on the first network slice information and the second network slice information, including: If the network slice identifier of the stationed cell does not contain the first network slice identifier, and at least one of the neighboring cell network slice identifiers partially or completely contains the first network slice identifier, the processing unit performs cell reselection.

10. The terminal device according to claim 7, characterized in that, The processing unit performs cell reselection based on the first network slice information and the second network slice information, including: The processing unit performs cell reselection when the number of network slices at the intersection of the stationary cell network slice identifier and the first network slice identifier is equal to the number of network slices at the intersection of at least one neighboring cell network slice identifier and the first network slice identifier, and the link quality of the stationary cell is lower than the link quality of the at least one neighboring cell.

11. The terminal device according to claim 7 or 9, characterized in that, The processing unit selects neighboring cells from the at least one neighboring cell where the number of network slices at the intersection of the neighboring cell's network slice identifier and the first network slice identifier is greater than the number of network slices at the intersection of the stationing cell's network slice identifier and the first network slice identifier for stationing, including: The processing unit selects the neighboring cell with the largest number of network slices that intersect with the first network slice identifier from the at least one neighboring cell and keeps it there.

12. The terminal device according to claim 11, characterized in that, The processing unit selects the neighboring cell with the largest number of network slices whose intersection with the first network slice identifier is found among the at least one neighboring cell for dwelling, including: When the number of network slices where the intersection of multiple neighboring network slice identifiers and the first network slice identifier is maximized, The processing unit selects the neighboring cell with the highest link quality from the plurality of neighboring cells to stay in; or, the terminal device selects the neighboring cell with the highest priority from the plurality of neighboring cells to stay in.

13. A communication device, characterized in that, include: A processor and a memory, the processor and the memory being communicatively coupled, the memory storing program instructions, wherein when the program instructions stored in the memory are executed by the processor, the cell selection method as described in any one of claims 1 to 6 is implemented.

14. A chip, characterized in that, The chip includes logic circuitry and an input / output interface. The input / output interface is used to communicate with modules outside the chip. The logic circuitry is used to run computer programs or instructions to implement the method as described in any one of claims 1 to 6.

15. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a communication device, cause the communication device to perform the method as described in any one of claims 1 to 6.

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