A communication method and related apparatus

Abstract

This application provides a communication method and related apparatus. The method includes: receiving first information, wherein the first information includes a list of Public Land Mobile Networks (PLMNs), wherein at least two PLMNs in the list have the same priority, and the PLMNs in the list are PLMNs that allow roaming access for terminal devices; and sending a first message to a first PLMN among the at least two PLMNs according to first parameters of the at least two PLMNs, wherein the first parameters include one or more of supported access technologies and supported service types, and the first message is used to request registration. This application embodiment can improve the user experience in roaming scenarios.

Description

Technical Field

[0001] This application relates to the field of wireless communication, and more particularly to a communication method and related apparatus. Background Technology

[0002] According to the 3rd Generation Partnership Project (3GPP) protocol TS23.122, after the terminal device is powered on or network coverage is restored, it should select a public land mobile network (PLMN) from the network search results in the following order:

[0003] 1. A successfully registered public terrestrial mobile network (PLMN, RPLMN);

[0004] 2. Home Public Land Mobile Network (HPLMN) / Equivalent Home Public Land Mobile Network (EHPLMN);

[0005] 3. User-controlled public terrestrial mobile network (UPLMN) files sorted according to preset priority in the files of the Universal Subscriber Identity Module (USIM) card (filename can be "user controlled PLMN selector with access technology");

[0006] 4. The USIM card file (the file name can be "operator controlled PLMN selector with access technology") contains operator-controlled public terrestrial mobile networks (OPLMN) sorted by preset priority;

[0007] 5. Other PLMNs with high-quality signals;

[0008] Among various PLMNs, all PLMNs except HPLMN and EHPLMN can be referred to as visited public terrestrial mobile networks (VPLMN).

[0009] When a terminal device is first powered on or network coverage is restored, it selects a network for access according to the network selection order described above. If the terminal device is in a roaming scenario, it can access a VPLMN and receive the Steering of Roaming (SoR) information sent by the HPLMN through the VPLMN. The SoR information contains a list of PLMNs, which includes the identity (ID) of each PLMN and the access technologies supported by each PLMN. The order of the IDs in the PLMN list is related to the priority of the PLMNs by default. For example, the PLMN with the first ID in the list (represented as PLMN ID 1) has the highest priority, the PLMN with the second ID (represented as PLMN ID 2) has the next highest priority, and so on, with the PLMN with the last ID (represented as PLMN ID n) having the lowest priority (n is the number of PLMNs in the SoR information). The terminal device can subsequently prioritize accessing higher-priority PLMNs based on the PLMN list in the network search results.

[0010] It is understandable that the PLMN list may contain multiple PLMNs with the same roaming rates but different priorities, which may affect the user experience.

[0011] For example, a terminal device may currently find two different PLMNs: a 2G PLMN (such as a Global System for Mobile Communications (GSM) network, denoted as PLMN_1GSM) and a 5G PLMN (such as a New Radio (NR) network, denoted as PLMN_2NR). If the roaming charges for PLMN GSM and PLMNNR are the same, and the terminal device determines that PLMN GSM has a higher priority based on the PLMN list, then the terminal device will prioritize accessing PLMN GSM. This would prevent the terminal device from providing users with higher-quality network services (such as higher-definition voice services and / or higher-speed data services), thus impacting the user experience. Summary of the Invention

[0012] This application provides a communication method and related apparatus that can improve the user experience in roaming scenarios.

[0013] In a first aspect, embodiments of this application provide a communication method applied to a terminal device, the method comprising:

[0014] Receive first information, wherein the first information includes a list of public land mobile networks (PLMNs), wherein at least two PLMNs in the PLMN list have the same priority, and the PLMNs in the PLMN list are PLMNs that allow terminal devices to roam and access.

[0015] Based on the first parameters of at least two PLMNs, a first message is sent to the first PLMN of the at least two PLMNs, wherein the first parameters include one or more of the supported access technologies and supported service types, and the first message is used to request registration.

[0016] In the above method, for roaming scenarios, after receiving the first information containing the PLMN priority, the terminal device can select from at least two PLMNs with the same priority to request registration with the first PLMN that better suits its network capabilities and service needs based on the first parameters (such as supported access technologies, supported service types, etc.), thereby improving the user experience in roaming scenarios.

[0017] In one alternative implementation, the first information also includes:

[0018] Priority or indication information for at least two PLMNs, where the indication information is used to indicate that at least two PLMNs have the same priority.

[0019] In the above method, the first information can display the priority of the PLMN, which is beneficial for the terminal device to select a suitable PLMN based on the PLMN priority in the first information.

[0020] In another alternative implementation, the first information may also include one or more of the following:

[0021] At least two PLMN-supported access technologies;

[0022] At least two PLMN-supported service types;

[0023] Predicted duration of at least two PLMNs being in a congested state.

[0024] In the above method, the first information also includes auxiliary information other than the priority of the PLMN. This auxiliary information is related to user experience and can help the terminal device to use this auxiliary information as the first parameter to select the first PLMN from at least two PLMNs with the same priority, thereby improving the user experience.

[0025] In another alternative implementation, at least two PLMNs satisfy one or more of the following conditions:

[0026] The roaming rates are the same;

[0027] The number of supported business types is the same.

[0028] In the above method, the priority of the PLMN is related to the roaming fee and / or the number of service types supported. It can be understood that the lower the roaming fee of the PLMN and / or the more service types the PLMN supports, the better the user experience of the terminal device after connecting to the PLMN.

[0029] In another alternative implementation, the first parameter also includes one or more of the following information:

[0030] Signal quality;

[0031] Predicted duration of congestion.

[0032] In another alternative implementation, the first PLMN satisfies one or more of the following conditions:

[0033] The first PLMN supports the first access technology, which is an access technology supported by the terminal equipment.

[0034] The first PLMN supports the first access technology, which is superior to the access technology of the PLMN currently connected to by the terminal device.

[0035] The first PLMN supports the first access technology, wherein the first access technology is the highest access technology supported by at least two PLMNs;

[0036] The first PLMN's access technology is an access technology supported by the terminal equipment.

[0037] The priority of the first PLMN is equal to or higher than the priority of the PLMN currently connected to the terminal device.

[0038] The access technology of the first PLMN is superior to the access technology of the PLMN currently connected to by the terminal device.

[0039] The first PLMN supports service types that meet the service preferences of terminal devices;

[0040] The first PLMN's access technology is the PLMN with the highest access technology among at least two PLMNs;

[0041] The first PLMN is the PLMN that supports the most service types among at least two PLMNs;

[0042] The first PLMN is the PLMN with the highest signal quality among at least two PLMNs;

[0043] The prediction duration of the first PLMN being in a congested state is no greater than the first preset threshold.

[0044] In another alternative implementation, before sending the first request message to the first PLMN of the at least two PLMNs based on the first parameters of the at least two PLMNs, the method further includes:

[0045] Candidate PLMNs are obtained by searching the network, wherein the candidate PLMNs include at least two PLMNs.

[0046] In another alternative implementation, the first PLMN has a higher priority than the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the first PLMN has a priority equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology of the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0047] The first parameter includes the access technology. Based on the first parameters of at least two PLMNs, a first message is sent to the first PLMN among the at least two PLMNs, including:

[0048] If none of the at least two PLMNs support the first access technology and the second access technology, then a first message is sent to the first PLMN based on the first access technology, wherein the second access technology is superior to the first access technology and is an access technology supported by the terminal device.

[0049] In the above method, the terminal device prioritizes accessing the first PLMN that supports the first access technology among at least two PLMNs with the same priority. The first access technology can be the highest access technology among the intersection of the access technologies supported by the at least two PLMNs and the access technologies supported by the terminal device. This is beneficial for the terminal device to obtain better services (such as higher-definition voice services and / or higher-speed data services) when interacting with the PLMN in subsequent services, thereby improving the user experience.

[0050] In another alternative implementation, the first PLMN has a higher priority than the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the first PLMN has a priority equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology of the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0051] At least two PLMNs also include a second PLMN. The first parameters include access technology and signal quality. Based on the first parameters of the at least two PLMNs, a first message is sent to the first PLMN of the at least two PLMNs, including:

[0052] If both the first PLMN and the second PLMN support the first access technology, and the signal quality of the first PLMN is higher than that of the second PLMN, then the first message is sent to the first PLMN based on the first access technology.

[0053] In the above method, for two PLMNs (or more PLMNs) with the same priority and supporting the same access technology, the terminal device can try to access the PLMN with higher signal quality first, so as to avoid network instability when interacting with the PLMN for services in the future and improve the user experience.

[0054] In another alternative implementation, the priority of the first PLMN is greater than or equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the priority of the first PLMN is equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology supported by the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0055] At least two PLMNs also include a second PLMN. The first parameter includes the access technology and supported service types. Based on the first parameter of the at least two PLMNs, a first message is sent to the first PLMN of the at least two PLMNs, including:

[0056] If both the first PLMN and the second PLMN support the first access technology, and the service type supported by the first PLMN meets the service preferences of the terminal device, while the service type supported by the second PLMN does not meet the service preferences of the terminal device, then a first message is sent to the first PLMN based on the first access technology; or,

[0057] If both the first PLMN and the second PLMN support the first access technology, and the number of service types supported by the first PLMN is greater than the number of service types supported by the second PLMN, then a first message is sent to the first PLMN based on the first access technology.

[0058] In the above method, for two PLMNs (or more PLMNs) with the same priority and supporting the same access technology, the terminal device can first try to access the PLMN whose supported service types meet the terminal device's service preferences, so as to ensure that the terminal device can carry out its preferred services after accessing the PLMN and improve the user experience.

[0059] Alternatively, for two (or more) PLMNs with the same priority and supporting the same access technologies, the terminal device can prioritize trying to connect to the PLMN that supports a larger number of service types. This ensures that the terminal device can perform more services after connecting to the PLMN, meet more user application needs, and improve user experience.

[0060] In another alternative implementation, the priority of the first PLMN is greater than or equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the priority of the first PLMN is equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology supported by the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0061] At least two PLMNs also include a second PLMN. The first parameter includes the predicted duration of access technology and congestion state. Based on the first parameter of the at least two PLMNs, a first message is sent to the first PLMN of the at least two PLMNs, including:

[0062] If both the first PLMN and the second PLMN support the first access technology, and the predicted duration of the first PLMN being in a congested state is less than the predicted duration of the second PLMN being in a congested state, then a first message is sent to the first PLMN based on the first access technology.

[0063] In the above method, for two PLMNs (or more PLMNs) with the same priority and supporting the same access technology, the terminal device can give priority to trying to access the PLMN with a shorter predicted congestion time. This helps to reduce the time the terminal device waits to process a certain service after accessing the PLMN and improves the user experience.

[0064] In yet another alternative implementation, the method further includes:

[0065] Receive a second message, wherein the second message is used in response to the first message, and the second message includes the service types supported by the first PLMN;

[0066] If the service types supported by the first PLMN do not meet the service preferences of the terminal device, a third message is sent to the second PLMN, wherein the third message is used to request registration.

[0067] In the above method, for at least two PLMNs with the same priority, the terminal device can obtain the service types supported by the first PLMN after attempting to connect to the first PLMN selected based on the first parameter. If the service types supported by the first PLMN do not meet the terminal device's service preferences, the terminal device can then attempt to connect to a second PLMN with the same priority as the first PLMN. This ensures that the terminal device can perform its preferred services after connecting to the PLMN, further improving the user experience.

[0068] In yet another alternative implementation, the method further includes:

[0069] Receive a second message, wherein the second message is used in response to the first message, and the second message includes the predicted duration of the first PLMN being in a congested state;

[0070] If the predicted duration of the congestion state of the first PLMN is greater than the first preset threshold, a third message is sent to the second PLMN, wherein the third message is used to request registration.

[0071] In the above method, for at least two PLMNs with the same priority, the terminal device can attempt to connect to the first PLMN selected based on the first parameter, and then obtain the predicted duration of the first PLMN being in a congested state. If the predicted duration of the first PLMN being in a congested state is greater than a first preset threshold, the terminal device can then attempt to connect to a second PLMN with the same priority as the first PLMN, so as to ensure that the terminal device can reduce the waiting time for processing a certain service after connecting to the PLMN, and further improve the user experience.

[0072] Secondly, embodiments of this application provide a communication method applied to a first network device, the method comprising:

[0073] Determine the first information, which includes a list of PLMNs, where at least two PLMNs in the list have the same priority;

[0074] Send the first message.

[0075] In the above method, the first network device can send first information containing the PLMN priority to the terminal device. This allows the terminal device to subsequently select from at least two PLMNs with the same priority to request registration with the first PLMN that better suits its network capabilities and service needs based on the first parameters (such as supported access technologies, supported service types, etc.), thereby improving the user experience in roaming scenarios.

[0076] In one alternative implementation, the first information further includes:

[0077] Priority or indication information for at least two PLMNs, where the indication information is used to indicate that at least two PLMNs have the same priority.

[0078] In the above method, the first information can display the priority of the PLMN, which is beneficial for the terminal device to select a suitable PLMN based on the PLMN priority in the first information.

[0079] In one alternative implementation, determining the first information includes:

[0080] First information is determined according to a first strategy, wherein the first strategy defines one or more of the following information:

[0081] If PLMNs have the same roaming rates, they have the same priority; and the lower the roaming rate of a PLMN, the higher its priority.

[0082] If a PLMN supports the same number of service types, it has the same priority; however, the more service types a PLMN supports, the higher its priority.

[0083] In the above method, the priority of the PLMN is related to the roaming tariff and / or the number of supported service types. The first network device can flexibly adjust the focus of priority determination according to different application scenarios.

[0084] In one alternative implementation, the first information further includes one or more of the following:

[0085] Access technologies for at least two PLMNs;

[0086] At least two PLMN-supported service types;

[0087] Predicted duration of at least two PLMNs being in a congested state.

[0088] In the above method, the first information also includes auxiliary information other than the priority of the PLMN. This auxiliary information is related to user experience and can help the terminal device to use this auxiliary information as the first parameter to select the first PLMN from at least two PLMNs with the same priority, thereby improving the user experience.

[0089] Thirdly, embodiments of this application provide a communication device, which may be a terminal device or a device or functional module in a terminal device, including a module for performing the method described in the first aspect or any possible implementation of the first aspect;

[0090] Alternatively, the communication device includes a processor for performing the method described in the first aspect or any possible implementation thereof.

[0091] Fourthly, embodiments of this application provide a communication device, which may be a first network device or a device or functional module in the first network device, including a module for performing the method described in the second aspect or any possible implementation of the second aspect;

[0092] Alternatively, the communication device includes a processor for performing the method described in the second aspect or any possible implementation thereof.

[0093] Fifthly, embodiments of this application provide a communication device, which includes logic circuitry and an interface coupled together; the interface is used for inputting and / or outputting information, wherein:

[0094] The logic circuit is used to execute the method of the first aspect or any possible implementation of the first aspect;

[0095] Alternatively, the logic circuit may be used to execute the second aspect or any possible implementation of the second aspect.

[0096] Sixthly, embodiments of this application provide a communication system, which includes a first communication device and a second communication device, wherein:

[0097] The first communication device is used to perform the method described in the first aspect or any possible implementation thereof, and the second communication device is used to perform the method described in the second aspect or any possible implementation thereof.

[0098] In a seventh aspect, embodiments of this application provide a computer-readable storage medium for storing a computer program, wherein:

[0099] When the computer program is executed, it is capable of implementing the first aspect or any possible implementation of the first aspect;

[0100] Alternatively, when the computer program is executed, it may be able to implement the second aspect or any possible implementation of the second aspect.

[0101] Eighthly, embodiments of this application provide a computer program product, the computer program product including instructions, wherein:

[0102] When this instruction is executed on the processor, it is capable of performing the method described in the first aspect or any possible implementation thereof;

[0103] Alternatively, when the instruction is run on the processor, it can perform the method described in the second aspect or any possible implementation of the second aspect.

[0104] The beneficial effects of the apparatus or product provided by any possible implementation of the third to eighth aspects of this application can be referred to the first to second aspects, as well as the beneficial effects of the technical solutions provided by any possible implementation of the first to second aspects, which will not be repeated here. Attached Figure Description

[0105] The accompanying drawings used in the embodiments of this application are described below.

[0106] Figure 1 This is a schematic diagram of the architecture of a communication system applicable to the embodiments of this application;

[0107] Figure 2 This is a flowchart illustrating a communication method provided in an embodiment of this application;

[0108] Figure 3 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0109] Figure 4 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0110] Figure 5 This is a flowchart illustrating another communication method provided in an embodiment of this application;

[0111] Figure 6 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0112] Figure 7 This is a schematic diagram of the structure of another communication device provided in the embodiments of this application;

[0113] Figure 8 This is a schematic diagram of the structure of another communication device provided in the embodiments of this application. Detailed Implementation

[0114] For ease of understanding, the following examples illustrate some concepts related to the embodiments of this application for reference. As follows:

[0115] 1. Public Land Mobile Network (PLMN): A cellular mobile communication network operating under a specific operator and using a specific standard within a country or region, providing terrestrial mobile communication services to the public. This network can interconnect with other communication networks such as the Public Switched Telephone Network (PSTN) to form a communication network covering the entire region or country. In practical applications, PLMNs from different countries and operators are distinguished by PLMN numbers. A PLMN number typically consists of two parts: a mobile country code (MCC) and a mobile network code (MNC). For example, China Mobile's PLMN number is 46000, where 460 is the MCC and 00 is the MNC.

[0116] 2. Roaming Area: In the telecommunications field, a roaming area (or roaming zone) refers to a location where the communication system can still provide service to a terminal device after it leaves its registered service area (i.e., its home service area or home location) and moves to another service area (i.e., the visited service area). Specifically, when a terminal device leaves its registered service area and enters a new service area, the communication network can still provide service; this new service area is the roaming area.

[0117] 3. Roaming Guidance Information (SoR): This is mainly used by the Public Land Mobile Network (HPLMN) of the terminal device's home location to guide the terminal device to select the visited network (i.e., VPLMN) of the roaming location.

[0118] 4. Congestion (or network congestion): This refers to a state in a packet-switched network where the number of packets transmitted is too large, causing a decline in network transmission performance due to the limited resources of store-and-forward nodes. Network congestion is a state of continuous overload where the demands of user equipment accessing the network on network resources (including link bandwidth, storage space, and processor processing power) exceed its inherent processing capacity and capacity.

[0119] The above descriptions of technical terms may be used in the embodiments below.

[0120] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0121] In this application, the terms "system" and "network" are used interchangeably. Unless otherwise stated, " / " indicates that the objects before and after are in an "or" relationship; for example, A / B can mean A or B. "And / or" in this application merely describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. Furthermore, in the description of this application, unless otherwise stated, "multiple" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be one or more. Furthermore, to facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish between network elements and similar items with essentially the same function. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0122] References to "one embodiment" or "some embodiments" in the embodiments described in this application mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0123] Furthermore, in the embodiments of this application, words such as "exemplary" and "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design scheme described as "exemplary" in this application should not be construed as being better or more advantageous than other embodiments or design schemes. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner. In the embodiments of this application, "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably, and it should be noted that their intended meanings are matched when their distinction is not emphasized.

[0124] The following detailed embodiments further illustrate the objectives, technical solutions, and beneficial effects of this application. It should be understood that the following are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made based on the technical solutions of this application should be included within the scope of protection of this application.

[0125] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0126] The technical solutions provided in this application can be applied to various communication systems, such as Long Term Evolution (LTE) systems, LTE frequency division duplex (FDD) systems, LTE time division duplex (TDD) systems, 5th generation (5G) systems, or new radio (NR) systems. Furthermore, they can also be applied to subsequent evolution systems, such as 6G communication systems. These systems can be classified according to their operating modes into frequency division duplex (FDD) systems and time division duplex (TDD) systems.

[0127] The system architecture used in the embodiments of this application is described below. It should be noted that the system architecture and business scenarios described in this application are for the purpose of more clearly illustrating the technical solutions of this application, and do not constitute a limitation on the technical solutions provided in this application. As those skilled in the art will know, with the evolution of system architecture and the emergence of new business scenarios, the technical solutions provided in this application are also applicable to similar technical problems.

[0128] Figure 1 This is a schematic diagram of the architecture of a communication system applicable to an embodiment of this application. For example... Figure 1 As shown, the communication system 10 includes a radio access network (RAN) 100 and a core network (CN) 200. RAN 100 includes at least one RAN device (such as...). Figure 1 110a and 110b (collectively referred to as 110) and at least one terminal device (such as Figure 1RAN 100, denoted as RAN 120a-120j, is collectively referred to as RAN 120. RAN 100 may also include other RAN equipment, such as wireless relay equipment and / or wireless backhaul equipment. Figure 1 (not shown in the image) etc. CN 200 includes at least one CN device 210.

[0129] Terminal device 120 is connected to RAN device 110 wirelessly, for example, via air interface technology (such as NR or LTE). RAN device 110 is connected to core network 200 wirelessly or via wired connection. CN device 210 in CN 200 and RAN device 110 in RAN 100 can be different physical devices, or they can be the same physical device integrating core network logical functions and radio access network logical functions.

[0130] RAN 100 can be a cellular system related to the 3rd Generation Partnership Project (3GPP), such as 4G, 5G mobile communication systems, or future-oriented evolution systems. RAN 100 can also be an open access network (O-RAN or ORAN), a cloud radio access network (CRAN), or a wireless fidelity (WiFi) system. RAN 100 can also be a communication system that integrates two or more of the above systems.

[0131] RAN equipment 110 forms part of the communication system, used to help terminal devices achieve wireless access. RAN equipment can also be called RAN nodes, RAN network elements, RAN entities, access nodes, etc. Multiple RAN devices 110 in communication system 10 can be of the same type or different types. In some scenarios, the roles of RAN equipment 110 and terminal device 120 are relative, for example... Figure 1 Network element 120i can be a helicopter or a drone, and it can be configured as a mobile base station. For terminal devices 120j that access RAN 100 through network element 120i, network element 120i is a base station; however, for base station 110a, network element 120i is a terminal device. RAN device 110 and terminal device 120 are sometimes referred to as communication devices, for example... Figure 1 Network elements 110a and 110b can be understood as communication equipment with base station functions, while network elements 120a-120j can be understood as communication equipment with terminal equipment functions.

[0132] In one alternative implementation, the RAN equipment can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB), a base station in a future mobile communication system, or an access node in a WiFi system, etc. The RAN equipment can also be a macro base station (such as...). Figure 1 110a), micro base stations or indoor stations (such as Figure 1 The RAN device can be a relay node or donor node (e.g., 110b), or a wireless controller in a CRAN scenario. Optionally, the RAN device can also be a server, wearable device, vehicle, or in-vehicle equipment. For example, the access network device in vehicle-to-everything (V2X) technology can be a roadside unit (RSU). All or part of the functions of the RAN device in this application can also be implemented through software functions running on hardware, or through virtualization functions instantiated on a platform (e.g., a cloud platform). The RAN device can also be equipped with communication modules, circuits, or chips that perform corresponding communication functions. The RAN device can also be configured with program instructions for performing corresponding communication functions and corresponding program instructions. The RAN device in this application can also be a logic device, logic module, or software capable of implementing all or part of the RAN device functions.

[0133] In one alternative implementation, multiple RAN devices collaborate to assist terminal devices in achieving wireless access, with each RAN device implementing a portion of the base station's functions. For example, the RAN devices can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), etc. The CU and DU can be configured separately or included in the same network element, such as a baseband unit (BBU). The RU can be included in radio equipment or radio units, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0134] In different systems, CU (or CU-CP and CU-UP), DU, or RU may have different names, but those skilled in the art will understand their meaning. For example, in an ORAN system, CU can also be called O-CU (open CU), DU can also be called O-DU, CU-CP can also be called O-CU-CP, CU-UP can also be called O-CU-UP, and RU can also be called O-RU. For ease of description, this application uses CU, CU-CP, CU-UP, DU, and RU as examples. Any of the units among CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0135] Terminal device 120 can be a device or module that accesses the aforementioned communication system and has corresponding communication functions. Terminal device can also be called a terminal, user equipment (UE), mobile station, mobile terminal, etc. Terminal device 120 can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart cities, etc. Terminal device can be a mobile phone, tablet computer, computer with wireless transceiver function, wearable device, vehicle, drone, helicopter, airplane, ship, robot, robotic arm, smart home device, transportation vehicle with wireless communication function, communication module, etc. The embodiments of this application do not limit the device form of the terminal device. Terminal device typically contains a communication module, circuit, or chip that performs the corresponding communication function. The terminal device can also be configured with program instructions for performing the corresponding communication function.

[0136] CN device 210 in CN 200 can implement one or more of the following network functions: Mobility Management Entity (MME), Access and Mobility Management Function (AMF), Authentication Server Function (AUSF), Session Management Function (SMF), User Plane Function (UPF), Policy Control Function (PCF), Policy and Charging Rules Function (PCRF), Edge Application Server Discovery Function (EASDF), Unified Data Management (UDM), Unified Data Repository (UDR), Home Subscriber Server (HSS), Centralized Network Configuration (CNC), Network Repository Function (NRF), Network Exposure Function (NEF), Local NEF (or L-NEF), Binding Support Function (BSF), Application Function (AF), etc. CN devices can also be called CN nodes, CN network elements, CN entities, etc.

[0137] The embodiments of this application aim to optimize the network selection process of terminal devices in roaming scenarios, thereby improving the user experience.

[0138] Please see Figure 2 , Figure 2 This is a flowchart illustrating a communication method provided in an embodiment of this application. The method can be based on... Figure 1 The architecture shown can be used to implement this method, but it can also be implemented based on other architectures. This method includes, but is not limited to, the following steps:

[0139] Step S201: The terminal device receives the first information from the first network device.

[0140] In this embodiment, the terminal device is in a roaming scenario, meaning it is in a roaming location. The first network device can be a CN device in the terminal device's home Public Land Mobile Network (HPLMN), capable of implementing authentication service (AUSF) and unified data management (UDM) functions. For further explanation of the terminal device and the CN device, please refer to [link to relevant documentation]. Figure 1 The relevant descriptions in the illustrated embodiments will not be repeated here.

[0141] The first piece of information may include a list of PLMNs. The PLMN list contains multiple PLMNs, and the PLMNs in the list are those that terminal devices are allowed to access while roaming. These PLMNs that allow terminal devices to access while roaming can also be called Visited Public Land Mobile Network (VPLMN), and the PLMN list can also be called a VPLMN list.

[0142] In one alternative implementation, all PLMNs in the PLMN list have different priorities.

[0143] In one alternative implementation, at least two PLMNs in the PLMN list have the same priority.

[0144] Optionally, the PLMN list may contain multiple PLMNs with different priorities.

[0145] Optionally, the first information displays an indication of the PLMN's priority. Specifically, for example, the first information includes the PLMN's priority or indication information, which can be used to indicate that at least two PLMNs have the same priority. Further optionally, the indication information can also be used to indicate that there are multiple PLMNs with different priorities in the PLMN list.

[0146] Optionally, the first information implicitly indicates the priority of the PLMN. Specifically, for example, if it is determined that all PLMNs in the PLMN list have the same priority, the first information may not include the PLMN's priority or indication information. That is, when the first information does not include the PLMN's priority or indication information, it implicitly indicates that all PLMNs in the PLMN list have the same priority.

[0147] Optionally, the first information may also include the access technologies supported by the PLMN.

[0148] Access technology, also known as network standard, is a crucial element in mobile communication. A PLMN can support one or more access technologies, including 5G, 4G, 3G, and 2G. Future technologies such as 6G can also be included. For example, a 2G-based access network can be called a GSM network, and a 3G-based access network can be called a UMTS terrestrial radio access network (UTRAN), where UMTS stands for Universal Mobile Telecommunications System. The 4G-based access network can be called the evolved UMTS terrestrial radio access network (E-UTRAN) network, while the 5G-based access network can be called the next generation radio access network (NG-RAN), or satellite NG-RAN.

[0149] Optionally, the first information also includes the types of services supported by the PLMN. These service types can include voice services, data services, SMS services, supplementary services, location services, etc. Voice services can also include voice calls, voice and video calls, etc. Data services can include web browsing, downloading / uploading data, etc. Supplementary services can also include call waiting, multi-party calls, etc.

[0150] Optionally, the first information also includes the predicted duration of the PLMN being in a congested state (or network congestion state). This predicted duration is the predicted length of time the PLMN will be in a congested state; it can also be understood as the predicted time required for the PLMN to recover from a congested state to a non-congested state. For an explanation of the congestion state, please refer to the explanation section on related concepts in the embodiments of this application described above; it will not be repeated here.

[0151] It is understood that the aforementioned first information may include information such as priority (or indication information), access technologies supported by the PLMN, service types supported by the PLMN, and the predicted duration of PLMN congestion, which may be partially or entirely included in the PLMN list. In this case, the first information need not include the information contained in the PLMN list in addition to the information in the PLMN list.

[0152] For example, the PLMN list can be shown in Table 1 (Table 1 is a PLMN list provided in an embodiment of this application):

[0153] Table 1 PLMN List

[0154]

[0155]

[0156] As shown in Table 1, the PLMN list includes m priorities (denoted as Priority_1, Priority_2, ..., Priority_m), where m is an integer greater than 0. Optionally, Priority_1 represents the highest priority, and Priority_m represents the lowest priority, meaning the priorities from Priority_1 to Priority_m decrease sequentially. Optionally, the priorities from Priority_1 to Priority_m increase sequentially. This application does not strictly limit how the PLMN list represents the priorities of PLMNs. It is understood that when m is 1, the PLMNs in the PLMN list have the same priority. Optionally, in this case, the PLMN list does not display the priorities, thus implicitly indicating that all PLMNs in the PLMN list have the same priority.

[0157] Furthermore, the PLMN list also includes a PLMN identifier to distinguish different PLMNs. It is understood that each PLMN has a unique PLMN ID, meaning that multiple PLMNs with the same ID do not exist. Optionally, the PLMN ID is the PLMN number (i.e., MCC + MNC). For an explanation of the PLMN number, please refer to the explanation of relevant concepts in the embodiments of this application described above; it will not be repeated here. Optionally, the PLMN ID is represented by other content specified in the protocol. Optionally, the PLMN ID includes indication information for indicating priority; in this case, the column indicating priority can be omitted from the PLMN list. For example, the PLMN ID in the PLMN list can be in the form of PLMN number + indication information. This application embodiment does not strictly limit the specific content of the PLMN ID and indication information.

[0158] As shown in Table 1, at least two PLMNs in the PLMN list can have the same priority. For example, k PLMNs (IDs PLMN ID 11, PLMN ID 12, ..., PLMN ID 1k) have the same priority and are all Priority_1, and j PLMNs (IDs m1, PLMN ID m2, ..., PLMN ID mj) have the same priority and are all Priority_m. Here, k and j are integers greater than 0.

[0159] Furthermore, the PLMN list also includes the access technologies supported by the PLMN. For example, as shown in Table 1, the PLMN identified as PLMNID 11 supports any one of the 5G, 4G, 3G and 2G access technologies, and the PLMN identified as PLMNID m1 supports any one of the 4G, 3G and 2G access technologies.

[0160] Optionally, the PLMN list also includes the service types supported by the PLMN. For example, as shown in Table 1, the PLMN with PLMN ID12 only supports voice services, while the PLMN with PLMN ID m2 supports either voice or data services. It is understandable that the PLMN list displays the service types supported by the PLMN and indirectly indicates the number of service types supported. For example, as shown in Table 1, the PLMN with PLMN ID 12 supports only one type of service, while the PLMN with PLMN ID m2 supports two types of services. Optionally, the PLMN list directly displays the number of service types supported by the PLMN (not shown in Table 1). For example, the PLMN list can add a column of information (such as values ​​1, 2, 3, etc.) to indicate the number of service types supported by the PLMN.

[0161] Optionally, the PLMN list may also include the predicted duration of PLMN congestion (not shown in Table 1). For example, the PLMN list may include a new column (e.g., 1 minute, 2 minutes, 3 minutes, etc.) to indicate the predicted duration.

[0162] It should be noted that the specific content and presentation of the PLMN list are not strictly limited in the embodiments of this application; Table 1 is only an example.

[0163] The following section explains how the first network device determines the first information.

[0164] In one optional implementation, the operator in the home location of the terminal device and the operator in the roaming location can agree in advance that the first network device can pre-obtain information on multiple PLMNs allowed for roaming access in the roaming location (such as PLMN ID, roaming tariff, access technology, supported service types / quantities, predicted congestion duration, etc.) to determine the first information. It is understood that different roaming locations correspond to different first information. Further optionally, the first network device can associate the first information with the Mobile Country Code (MCC) of the roaming location to distinguish the first information corresponding to different roaming locations.

[0165] Optionally, the first network device determines the priority of multiple PLMNs in the first information according to the first policy.

[0166] The first strategy defines one or more of the following information:

[0167] If PLMNs have the same roaming rates, they have the same priority; and the lower the roaming rate of a PLMN, the higher its priority.

[0168] If a PLMN supports the same number of service types, it has the same priority; however, the more service types a PLMN supports, the higher its priority.

[0169] In other words, the priority of a PLMN is related to its roaming rates and / or the number of service types it supports. Understandably, the lower the roaming rates and / or the more service types a PLMN supports, the better the user experience will be for the terminal device after connecting to the PLMN.

[0170] For example, the priority of a PLMN is only related to its roaming tariff. The first network device will determine the priority of multiple PLMNs in order of roaming tariff from low to high, wherein the lower the roaming tariff, the higher the priority of the PLMN. When at least two PLMNs among the multiple PLMNs have the same roaming tariff, the at least two PLMNs have the same priority.

[0171] Optionally, in this embodiment, "at least two PLMNs have the same roaming charges" can be understood as at least two PLMNs having completely identical roaming charges, or it can be understood as at least two PLMNs having roaming charges within the same preset threshold range. That is, when the roaming charges of at least two PLMNs are not significantly different, they can be considered to have the same roaming charges. For example, the first network device can determine the roaming charge range of each PLMN based on multiple preset threshold ranges (each preset threshold range represents a roaming charge range, consisting of a range from a low threshold to a high threshold), and consider at least two PLMNs with roaming charges within the same preset threshold range as PLMNs with the same roaming charges. It is understood that among the multiple preset threshold ranges, the PLMNs corresponding to preset threshold ranges with lower high thresholds (or higher low thresholds) have higher priority.

[0172] Optionally, the roaming charges of a PLMN are related to the types of services it supports. For example, when a PLMN supports both voice and data services, its roaming charges include both voice and data roaming charges. The voice roaming charge can be equal to the product of the voice roaming unit price and the preset voice duration, while the data roaming unit price can be equal to the product of the data traffic unit price and the data transmission duration. For a PLMN with only one type of service roaming charge, the roaming charge is that specific service roaming charge. For a PLMN with multiple service roaming charges, the first network device can set corresponding weights (also known as weight values) for each service roaming charge to determine the PLMN's roaming charges. For example, the first network device can set the weight of the voice service roaming charge to 30% and the weight of the data service roaming charge to 70%, then the PLMN's roaming charges can be calculated using the following formula:

[0173] Roaming charges = 30% of voice service roaming charges + 70% of data service roaming charges

[0174] It should be noted that the specific algorithm for PLMN roaming charges in this application embodiment is not strictly limited. The specific algorithm can be agreed upon in advance by the operator in the home location of the terminal device and the operator in the roaming location.

[0175] For example, the priority of a PLMN is only related to the number of service types it supports. The first network device will determine the priority of multiple PLMNs in descending order of the number of service types they support, where the more service types a PLMN supports, the higher its priority. When at least two PLMNs support the same number of service types, the at least two PLMNs have the same priority.

[0176] For example, the priority of a PLMN is related to the PLMN's roaming rates and the number of service types supported by the PLMN.

[0177] Optionally, the first network device determines the priority of multiple PLMNs according to the order of roaming charges from low to high and the order of the number of service types supported by each PLMN from high to low. The order of roaming charges from low to high takes precedence over the order of the number of service types supported from high to low. When at least two PLMNs have the same roaming charges and the same number of service types supported, these at least two PLMNs have the same priority. For example, for five PLMNs (PLMN_1, PLMN_2, PLMN_3, PLMN_4, and PLMN_5), the roaming charges of the five PLMNs are compared first. If PLMN_1 has the lowest roaming charge, PLMN_5 has the highest roaming charge, and PLMN_2, PLMN_3, and PLMN_4 have the same roaming charge with a charge between PLMN_1 and PLMN_5, then PLMN_1 has the highest priority, and PLMN_5 has the lowest priority. Next, comparing the number of service types supported by PLMN_2, PLMN_3, and PLMN_4, if PLMN_2 and PLMN_3 support the same number of service types but fewer than PLMN_4, then PLMN_2 and PLMN_3 have the same priority but lower priority than PLMN_4. In other words, the five PLMNs are arranged in descending order of priority as follows: PLMN_1, PLMN_4, PLMN_2, PLMN_3, PLMN_5.

[0178] Optionally, the first network device assigns corresponding weights (also known as weight values) to the PLMN's roaming charges and the number of service types supported by the PLMN to determine the PLMN's priority. For example, the first network device can set the weight of the PLMN's roaming charges to 90% and the weight of the number of service types supported by the PLMN to 10%, calculating the priority indicators for multiple PLMNs. It can be understood that the PLMN's priority indicators can be calculated using the following formula:

[0179] Priority metric = roaming fee * 90% + number of supported service types * 10%

[0180] Subsequently, the first network device can determine the priorities of multiple PLMNs in ascending order of priority indicators. The lower the priority indicator, the higher the priority of the PLMN. When at least two PLMNs have the same priority indicator, these at least two PLMNs are considered to have the same priority. Optionally, when calculating the priority indicator, the terminal device can perform mathematical transformation or mapping on the roaming charges of the PLMNs, which helps to adjust the order of magnitude of the roaming charges to be the same as the number of supported service types.

[0181] This application does not strictly limit how the first network device determines the priority of multiple PLMNs in the first information according to the first strategy; the above is merely an example.

[0182] In one optional implementation, the first information is sent from the first network device to the terminal device via a second network device. The second network device can be a CN device in the PLMN selected from the network search results by the terminal device after initial power-on or network coverage restoration in the roaming area, following the network selection order specified in the communication protocol (e.g., the network selection order described in the background section above). This can enable functions such as AUSF and UDM. For an explanation of the CN device, please refer to [link to relevant documentation]. Figure 1 The relevant descriptions in the illustrated embodiments will not be repeated here. For ease of description, the PLMN that the terminal device initially selects to access after its first power-on in the roaming area or after network coverage is restored will be referred to as the third PLMN.

[0183] Furthermore, when the terminal device selects to access the third PLMN, it sends a fourth message (through the RAN device in the third PLMN) to the second network device to request registration. Upon receiving the fourth message, the second network device executes the registration process. During this process, the second network device authenticates the terminal device's identity information, interacts with the first network device in the terminal device's home region, and receives first information sent by the first network device. Optionally, when the second network device interacts with the first network device, the first network device obtains the MCC of the third PLMN to determine the terminal device's roaming location, and can then send the first information corresponding to that country code to the second network device.

[0184] Optionally, the first information is carried in a fifth message sent from the second network device to the terminal device (i.e., the fifth message includes the first information). The fifth message is used in response to the fourth message and can indicate successful registration.

[0185] Optionally, after the terminal device successfully registers with the third PLMN, if the first network device determines to update the first information, the first network device sends the updated first information to the terminal device through the second network device. For example, the first network device can determine to update the first information when any of the following conditions a to c occur:

[0186] Scenario a. The pre-agreed agreement between the operator in the terminal device's home location and the operator in the roaming location changes.

[0187] Scenario b. The multiple PLMNs allowed for roaming access in the roaming area included in the first information have changed (e.g., there are PLMN deletions and / or additions).

[0188] Scenario c. The information in the first information, including the priority of the PLMNs, the supported access technologies and / or the supported service types among the multiple PLMNs that allow roaming access in the roaming area, changes.

[0189] This application does not limit whether the first information is the first information obtained when the terminal device requests to register the third PLMN, or the updated first information obtained after the terminal device has successfully registered with the third PLMN.

[0190] In this application embodiment, the names of the first information and the message carrying the first information are not limited. For example, the first information can be called SoR information, and the message carrying the first information (such as the fifth message) can be called a registration receiving message or a downlink non-access stratum (NAS) direct transmission message.

[0191] Optionally, after receiving the first information, the terminal device sends a sixth message to the first network device through the second network device. The sixth message is used to indicate that the first information has been received.

[0192] Optionally, the terminal device stores the first information in its own USIM. For example, the first information can be stored in a file on the USIM card (e.g., a file named "operator controlled PLMN selector with access technology"), or the first network device can create a new file on the USIM card to store the first information. It is understood that after the terminal device is powered on again or network coverage is restored, it selects a network according to the network selection order specified in the communication protocol. If the MCC of the roaming location matches the MCC corresponding to the first information in the USIM, network selection can be performed based on the first information.

[0193] Optionally, the terminal device stores the first information in its own non-volatile memory (NVM). It is understood that after the terminal device powers on again or network coverage is restored, it selects a network according to the network selection order specified in the communication protocol. If its own USIM does not contain a file containing the first information, the terminal device may select a network based on the first information in the NVM if the MCC of the roaming location matches the MCC corresponding to the first information in the UVM.

[0194] Furthermore, after receiving the first information, the terminal device can obtain a candidate PLMN by searching the network (hereinafter referred to as network search). It is understood that the candidate PLMN is the PLMN obtained by the terminal device in its current geographical location / current roaming environment, and the candidate PLMN can provide network coverage for the terminal device's current geographical location. Optionally, when the terminal device searches the network, it searches sequentially according to a preset order (such as from high to low or from low to high) based on the access technologies it supports. It is understood that in this embodiment, the higher the service bandwidth and / or the lower the service latency corresponding to the access technology, the higher the access technology. For example, if the terminal device supports four generations of access technologies—2G, 3G, 4G, and 5G—then the order of these four generations of access technologies from high to low is: 5G, 4G, 3G, 2G. When searching the network, the terminal device can sequentially search each access technology across the entire frequency band according to this order, which helps reduce the number of standard conversions, saves search time, and improves user experience.

[0195] Optionally, if the terminal device determines, based on the first information, that the currently accessed PLMN (e.g., the third PLMN) does not meet the preset conditions, it will perform a network search to obtain candidate PLMNs. The preset conditions may include:

[0196] The priority of the currently accessing PLMN is higher than or equal to the highest priority of the PLMN in the first information, and the access technology of the currently accessing PLMN is the highest access technology supported by the terminal device.

[0197] It is understood that the PLMN currently accessed by the terminal device is one that the terminal device has successfully roamed into. Optionally, the first information includes the priority of the currently accessed PLMN, and the terminal device determines the priority of the currently accessed PLMN based on the first information. If the priority of the currently accessed PLMN is not equal to the highest priority of the PLMN in the first information, and / or the access technology of the currently accessed PLMN is not the highest access technology supported by the terminal device, the terminal device performs a network search to obtain candidate PLMNs. It is understood that network search helps the terminal device find PLMNs with higher priority and / or higher supported access technologies, thereby improving the user experience. Optionally, the network search method can be immediate network search or background network search. Immediate network search can be understood as the terminal device immediately stopping the ongoing service with the currently accessed PLMN and searching for a network. Background network search can be understood as performing a network search during idle periods (i.e., periods when there is no service interaction between the terminal device and the currently accessed PLMN).

[0198] Furthermore, the terminal device can determine the priority of the candidate PLMN based on the first information. Optionally, the terminal device can also determine information such as the service types and the number of supported service types of the candidate PLMN based on the first information. When searching for a network, the terminal device can obtain the access technologies supported by the candidate PLMN, and optionally, the terminal device can also obtain the signal quality of the candidate PLMN.

[0199] Terminal devices can prioritize and attempt to connect to PLMNs with higher priorities than the PLMN they are currently connected to, from highest to lowest priority. If the higher-priority PLMN connection fails, the terminal device can then attempt to connect to a PLMN with the same priority as the currently connected PLMN. If the connection to that PLMN also fails, the terminal device can remain on the currently connected PLMN. Specifically, "attempting to connect to (PLMN)" as described in this application embodiment can refer to sending a registration request message to the CN device of that PLMN, and "(PLMN) connection failure" can refer to a CN device that has not successfully registered with that PLMN.

[0200] Optionally, the reasons for access failure include one or more of the following reasons a to c:

[0201] Reason a. The terminal device did not receive the message from the PLMN in response to the registration request.

[0202] Reason b. The terminal device determines that the service types supported by the PLMN do not meet the terminal device's service preferences.

[0203] Reason c. The predicted duration for which the terminal device determines that the PLMN is in a congested state is greater than the first preset threshold.

[0204] It should be noted that the "receiving messages sent by the PLMN" described in the embodiments of this application can specifically refer to receiving messages sent by the CN device in the PLMN.

[0205] Furthermore, since the first information contains PLMNs with the same priority, the candidate PLMNs can include PLMNs with the same priority. In an optional implementation, the candidate PLMNs include at least two PLMNs with the same priority. When the terminal device attempts to access a PLMN with a priority higher than or equal to the priority of the PLMN currently accessed by the terminal device, in descending order of priority, step S202 can be used to preferentially attempt to access the first PLMN among the at least two PLMNs with the same priority.

[0206] Step S202: The terminal device sends a first message to the first PLMN among the at least two PLMNs based on the first parameters of the at least two PLMNs.

[0207] Specifically, the first message can be used to request registration. The first parameter can include at least one or more of the supported access technologies and supported service types. Optionally, the first parameter may also include one or more of the signal quality and the predicted duration of congestion.

[0208] It is understandable that higher levels of supported access technologies, a wider range of supported service types, higher signal quality, and shorter predicted congestion duration all contribute to improved user experience. It should be noted that the "sending a message to the PLMN (e.g., sending a first message to the first PLMN)" described in this embodiment specifically refers to sending a message to the CN device within the PLMN.

[0209] Optionally, the first PLMN satisfies one or more of the following conditions a to h:

[0210] Condition a. The first PLMN supports a first access technology, wherein the first access technology is an access technology supported by the terminal device.

[0211] Condition b. The first PLMN supports a first access technology, wherein the first access technology is superior to the access technology of the PLMN currently accessed by the terminal device.

[0212] Condition c. The first PLMN supports the first access technology, wherein the first access technology is the highest access technology supported by at least two PLMNs.

[0213] Condition d. The priority of the first PLMN is equal to or higher than the priority of the PLMN currently connected to the terminal device.

[0214] Condition e. The service types supported by the first PLMN meet the service preferences of the terminal device.

[0215] In this context, the service preference of a terminal device can be understood as the services that the terminal device tends to / prioritizes, the services that the terminal device frequently processes, or the services that are related to the main purpose / application scenario of the terminal device. For example, when the terminal device is a mobile phone or other device that prioritizes voice services (such as voice calls), its service preference is voice services; when the terminal device is a computer or other device that prioritizes data services (such as browsing web pages), its service preference is data services.

[0216] In practical applications, the service preferences of terminal devices can be configured by default or according to actual needs in the terminal device's "usage settings." For example, a terminal device configured with voice-centric mode has its service preference set to voice services, while a terminal device configured with data-centric mode has its service preference set to data services. It is understandable that a terminal device with a service preference set to voice services may still need to perform data services, and a terminal device with a service preference set to data services may still need to access voice services.

[0217] Condition f. The first PLMN is the PLMN that supports the most service types among at least two PLMNs.

[0218] Condition g. The first PLMN is the PLMN with the highest signal quality among at least two PLMNs.

[0219] As mentioned earlier, terminal devices can obtain the signal quality of candidate PLMNs during network search. Specifically, signal quality can be judged by some signal indicators, such as Receive Signal Channel Power (RSCP). Understandably, the higher the RSCP, the higher the signal quality.

[0220] Condition h. The prediction duration of the first PLMN being in a congested state is not greater than the first preset threshold.

[0221] For explanations of the technical terms involved in the above conditions, such as priority, access technology, number of service types, and predicted duration of congestion, please refer to the relevant descriptions in step S201, which will not be repeated here.

[0222] The following text uses the example of "the first parameter includes at least the supported access technologies" to further explain step S201.

[0223] In one alternative implementation, the first parameter includes at least the supported access technologies, and the first PLMN of at least two PLMNs satisfies one of the following conditions a and b:

[0224] Condition a. The priority of the first PLMN is higher than the priority of the PLMN currently connected to by the terminal device, and the first PLMN supports the first access technology, wherein the first access technology is an access technology supported by the terminal device.

[0225] Condition b. The priority of the first PLMN is equal to the priority of the PLMN currently connected to by the terminal device. The first PLMN supports the first access technology, wherein the first access technology is higher than the access technology of the PLMN currently connected to by the terminal device, and is an access technology supported by the terminal device.

[0226] Optionally, if none of the at least two PLMNs support the first access technology and the second access technology, the terminal device sends a first message to the first PLMN based on the first access technology, wherein the second access technology is superior to the first access technology and is an access technology supported by the terminal device.

[0227] Understandably, the first access technology can be the highest-ranking access technology among the intersection of the access technologies supported by at least two PLMNs and the access technologies supported by the terminal device. For example, if the terminal device supports 5G, 4G, 3G, and 2G access technologies, and the at least two PLMNs include a first PLMN supporting 4G, 3G, and 2G and a second PLMN supporting 3G and 2G, then the access technologies supported by the at least two PLMNs can be considered to include 4G, 3G, and 2G, and the highest-ranking access technology among the intersection of these and the access technologies supported by the terminal device is 4G.

[0228] Terminal devices should prioritize accessing the first PLMN that supports the first access technology among at least two PLMNs with the same priority. This is beneficial for obtaining better services (such as higher-definition voice services and / or higher-speed data services) from the PLMN when interacting with the PLMN in subsequent business interactions, thereby improving the user experience.

[0229] Optionally, the first parameter also includes signal quality, and the at least two PLMNs also include a second PLMN. If both the first PLMN and the second PLMN support the first access technology, and the signal quality of the first PLMN is higher than that of the second PLMN, the terminal device sends a first message to the first PLMN based on the first access technology.

[0230] Understandably, when faced with two (or more) PLMNs with the same priority and supporting the same access technology, terminal devices can prioritize trying to connect to the PLMN with higher signal quality to avoid network instability when interacting with the PLMN for services, thereby improving the user experience.

[0231] Optionally, the first parameter also includes supported service types, and the at least two PLMNs also include a second PLMN. If both the first PLMN and the second PLMN support the first access technology, and the service types supported by the first PLMN meet the service preferences of the terminal device, while the service types supported by the second PLMN do not meet the service preferences of the terminal device, the terminal device sends the first message to the first PLMN based on the first access technology.

[0232] Understandably, when faced with two (or more) PLMNs with the same priority and supporting the same access technologies, a terminal device can prioritize trying to access the PLMN whose supported service types match the terminal device's service preferences. This ensures that the terminal device can perform its preferred services after accessing the PLMN, thereby improving the user experience.

[0233] Alternatively, if both the first PLMN and the second PLMN support the first access technology, and the number of service types supported by the first PLMN is greater than the number of service types supported by the second PLMN, the terminal device sends a first message to the first PLMN based on the first access technology.

[0234] Understandably, when faced with two (or more) PLMNs with the same priority and supporting the same access technologies, terminal devices can prioritize trying to connect to the PLMN that supports a larger number of service types. This ensures that the terminal device can perform more services after connecting to the PLMN, meet more user application needs, and improve user experience.

[0235] Optionally, the first parameter also includes the predicted duration of congestion, and the at least two PLMNs also include a second PLMN. If both the first PLMN and the second PLMN support the first access technology, and the predicted duration of congestion for the first PLMN is less than the predicted duration of congestion for the second PLMN, the terminal device sends a first message to the first PLMN based on the first access technology.

[0236] Understandably, when faced with two (or more) PLMNs with the same priority and supporting the same access technology, terminal devices can prioritize trying to connect to the PLMN with the shorter predicted congestion time. This helps reduce the waiting time for terminal devices to process a service after connecting to the PLMN, thus improving user experience. It should be noted that the predicted duration can be greater than or equal to 0. When the predicted duration is 0, it indicates that the PLMN is in a non-congested state.

[0237] In one alternative implementation, the terminal device receives a second message sent by the first PLMN, wherein the second message is used to respond to the first message.

[0238] Optionally, the second message is used to indicate successful registration. After receiving the second message, the terminal device resides in the first PLMN.

[0239] Optionally, the at least two PLMNs may also include a second PLMN, and the second message includes the service types supported by the first PLMN. If the service types supported by the first PLMN do not meet the service preferences of the terminal device, the terminal device sends a third message to the second PLMN, wherein the third message is used to request registration. Otherwise (i.e., if the service types supported by the first PLMN meet the service preferences of the terminal device), the terminal device resides in the first PLMN.

[0240] Optionally, the at least two PLMNs may also include a second PLMN, and the second message includes the predicted duration of the first PLMN being in a congested state. If the predicted duration of the first PLMN being in a congested state is greater than a first preset threshold, the terminal device sends a third message to the second PLMN. Otherwise (i.e., if the predicted duration of the first PLMN being in a congested state is less than or equal to the first preset threshold), the terminal device resides in the first PLMN.

[0241] Understandably, given at least two PLMNs with the same priority, a terminal device can attempt to connect to the first PLMN selected based on a first parameter, and obtain the service types supported by the first PLMN and / or the predicted duration of congestion. If the service types supported by the first PLMN do not meet the terminal device's service preferences and / or the predicted duration of congestion exceeds a first preset threshold, the terminal device will then attempt to connect to the second PLMN with the same priority as the first PLMN. This ensures that after connecting to a PLMN, the terminal device can perform its preferred services and / or reduce the waiting time for processing a certain service, further improving the user experience.

[0242] In one optional implementation, the at least two PLMNs further include a second PLMN. After sending the first message, if the waiting time for the terminal device to receive the second message exceeds a second preset threshold, the terminal device sends a third message to the second PLMN.

[0243] Understandably, for at least two PLMNs with the same priority, the terminal device can try to connect to the first PLMN selected based on the first parameter. If no response message is received from the first PLMN within a certain period of time, it can then try to connect to the second PLMN with the same priority as the first PLMN. This saves the time the terminal device spends connecting to the PLMN and further improves the user experience.

[0244] In this embodiment of the application, after the terminal device sends a message (such as a first message) to the PLMN (such as a first PLMN) to request registration, any of the following situations a to c can be regarded as "PLMN access failure", that is:

[0245] Scenario a. The terminal device does not receive a response message (such as the second message) from the PLMN for the message used to request registration.

[0246] Scenario b. The terminal device determines that the service types supported by the PLMN do not meet the terminal device's service preferences.

[0247] Scenario c. The terminal device determines that the predicted duration of the PLMN being in a congested state is greater than the first preset threshold.

[0248] In one alternative implementation, in addition to at least two PLMNs with the same priority (such as the first PLMN and the second PLMN), the candidate PLMNs obtained by the terminal device during network search also include a third PLMN. The access technology of this third PLMN is lower than that of the first PLMN and the second PLMN. Therefore, if access to the first PLMN and the second PLMN fails, the terminal device attempts to access the third PLMN, that is, it sends a message to the third PLMN to request registration.

[0249] If the third PLMN fails to connect, and the candidate PLMNs obtained from the network search include a fourth PLMN, the fourth PLMN has a lower priority than the first and second PLMNs, and the fourth PLMN meets either condition a or b, then, in the case of the third PLMN failure, the terminal device attempts to connect to the fourth PLMN by sending a message to the fourth PLMN requesting registration.

[0250] Condition a. The priority of the fourth PLMN is higher than the priority of the PLMN currently connected to by the terminal device, and the fourth PLMN supports the first access technology, wherein the first access technology is an access technology supported by the terminal device.

[0251] Condition b. The priority of the fourth PLMN is equal to the priority of the PLMN currently connected to by the terminal device. The fourth PLMN supports the first access technology, wherein the first access technology is higher than the access technology of the PLMN currently connected to by the terminal device, and is an access technology supported by the terminal device.

[0252] If the third PLMN fails to connect, and the candidate PLMNs obtained from the network search do not include the fourth PLMN or the fourth PLMN fails to connect, then the terminal device will continue to reside in the current PLMN.

[0253] Therefore, Figure 2 In the illustrated embodiment, for roaming scenarios, after receiving the first information containing the PLMN priority, the terminal device can select from at least two PLMNs with the same priority to request registration with the first PLMN that better suits its network capabilities and service needs based on the first parameters (such as supported access technologies, supported service types, etc.), thereby improving the user experience in roaming scenarios.

[0254] Furthermore, when the first parameter includes multiple parameters, the terminal device can use the access technology in the first parameter as the primary parameter when selecting a network, and use other parameters in the first parameter (such as signal quality, supported service types, and predicted duration of congestion) as secondary parameters when selecting a network. This is beneficial for the terminal device to choose from at least two PLMNs with the same priority and access technology to request registration from the first PLMN, which has higher signal quality, supports service types that meet its service needs, supports more service types, or has a shorter predicted duration, thereby further improving the user experience in roaming scenarios.

[0255] It should be noted that the above implementation is only illustrative. The embodiments of this application do not impose strict restrictions on how the terminal device selects the first PLMN from at least two PLMNs with the same priority based on the first parameter (that is, which parameter in the first parameter is used as the primary parameter and which parameter is used as the secondary parameter).

[0256] The following text combines Figures 3 to 5 right Figure 2 The illustrated examples are further explained in detail.

[0257] Please see Figure 3 , Figure 3 This is a flowchart illustrating another communication method provided in an embodiment of this application. This method can be based on... Figure 1 The architecture shown can be used to implement this method, but it can also be implemented based on other architectures. This method includes, but is not limited to, the following steps:

[0258] Step S301: The terminal device receives the first information from the first network device.

[0259] For explanations regarding the terminal device, the first network device, and the first information, please refer to [link / reference]. Figure 2 The relevant descriptions in step S201 of the illustrated embodiment will not be repeated here.

[0260] Step S302: The terminal device determines whether the currently accessed PLMN meets the preset conditions based on the first information.

[0261] For an explanation of the preset conditions, please refer to [link / reference]. Figure 2 The relevant descriptions in step S201 of the illustrated embodiment will not be repeated here.

[0262] If so (i.e., if the currently accessed PLMN meets the preset conditions), the terminal device can execute step S310.

[0263] If not (i.e., if the currently accessed PLMN does not meet the preset conditions), the terminal device can execute step S303.

[0264] Step S303: The terminal device obtains the candidate PLMN by searching the network.

[0265] Please refer to the explanation of the candidate PLMNs. Figure 2 The relevant descriptions in step S201 of the illustrated embodiment will not be repeated here.

[0266] Step S304: The terminal device determines whether there is a PLMN among the candidate PLMNs that has not been attempted to connect and has a higher priority than the currently connected PLMN.

[0267] If so (i.e., if there is a PLMN among the candidate PLMNs that has not been attempted to connect and has a higher priority than the currently connected PLMN), the terminal device can execute step S305.

[0268] If not (i.e., if there is no PLMN among the candidate PLMNs that has not been attempted to connect and has a higher priority than the currently connected PLMN), the terminal device can execute step S308.

[0269] Step S305: The terminal device attempts to connect to a PLMN with the highest priority among the candidate PLMNs.

[0270] The first priority is the highest priority among the PLMNs that have not yet attempted to connect to the candidate PLMNs.

[0271] Specifically, when the candidate PLMNs include only one with a first priority, the terminal device can attempt to access the PLMN based on the highest access technology among the intersection of the PLMN's supported access technologies and the terminal device's supported access technologies, according to a first parameter. Optionally, the first parameter may include other parameters besides access technology, and the terminal device needs to further consider other factors when attempting to access the PLMN. For example, the first parameter may also include supported service types. When prioritizing access to the PLMN based on a high-priority access technology, the terminal device also needs to consider whether the PLMN's supported service types meet the terminal device's service preferences. If they do, the terminal device attempts to access the PLMN. If not, the terminal device attempts to access the PLMN based on a low-priority access technology.

[0272] When the candidate PLMNs include at least two PLMNs with a first priority, the terminal device may attempt to connect to the first PLMN among the at least two PLMNs with a first priority, based on a first parameter. Optionally, if the first PLMN connection fails, the terminal device may attempt to connect to the second PLMN and / or the third PLMN (if a third PLMN exists). In this case, the first PLMN, the second PLMN, and the third PLMN all meet the following conditions: their priority is higher than the priority of the PLMN currently being connected to by the terminal device, and they support the first access technology, wherein the first access technology is an access technology supported by the terminal device.

[0273] For a detailed explanation of the first parameter, the first PLMN, the second PLMN, and the third PLMN, please refer to [link / reference needed]. Figure 2 The relevant descriptions in step S202 of the illustrated embodiment will not be repeated here.

[0274] If one of the PLMNs with the highest priority successfully connects, the terminal device can execute step S306.

[0275] If all attempts to connect to the PLMN with the highest priority fail, the terminal device can execute step S304.

[0276] Step S306: The terminal device resides in the PLMN it is attempting to access.

[0277] It is understandable that after a PLMN connection attempt is successful, the terminal device can regard the successfully connected PLMN as the new currently connected PLMN.

[0278] Step S307: The terminal device determines whether the dwell time in the currently accessed PLMN exceeds the preset third preset threshold.

[0279] If (i.e., if the dwell time of the terminal device in the currently accessed PLMN exceeds the preset third preset threshold), the terminal device can return to execute step S303.

[0280] If not (i.e., if the dwell time of the terminal device in the currently accessed PLMN does not exceed the preset third preset threshold), the terminal device can continue to execute step S310.

[0281] Optionally, the terminal device can start a timer to determine whether the dwell time exceeds a preset third threshold.

[0282] Step S308: The terminal device determines whether there is a PLMN among the candidate PLMNs that has not been attempted to connect and has a priority of second priority.

[0283] The second priority is the priority of the PLMN currently connected to the terminal device.

[0284] If so (i.e., if there is a PLMN among the candidate PLMNs that has not been attempted to connect and has a priority of the second priority), the terminal device can execute step S309.

[0285] If not (i.e., if there is no PLMN among the candidate PLMNs that has not been attempted to connect and has a priority of second priority), the terminal device can execute step S310.

[0286] Step S309: The terminal device attempts to connect to a PLMN with the second highest priority among the candidate PLMNs.

[0287] Specifically, when the candidate PLMNs include only one PLMN with a second-highest priority, the terminal device can attempt to access the PLMN based on the highest access technology among the intersection of the PLMN's supported access technologies and the terminal device's supported access technologies, according to the first parameter. Optionally, the first parameter may include other parameters besides access technologies, and the terminal device needs to further consider other factors when attempting to access the PLMN. For example, the first parameter may also include supported service types. When prioritizing access to the PLMN based on a high-priority access technology, the terminal device also needs to consider whether the PLMN's supported service types meet the terminal device's service preferences. If they do, the terminal device attempts to access the PLMN; otherwise, it attempts to access the PLMN based on a low-priority access technology (with a higher priority than the PLMN currently being accessed by the terminal device).

[0288] When the candidate PLMNs include at least two PLMNs with a priority of second priority, the terminal device may, based on a first parameter, attempt to connect to the first PLMN among the at least two PLMNs with a priority of second priority. Optionally, if the first PLMN connection fails, the terminal device may attempt to connect to the second PLMN and / or the third PLMN (if a third PLMN exists). In this case, the first PLMN, the second PLMN, and the third PLMN all meet the following conditions: their priority is equal to the priority of the PLMN currently connected to by the terminal device, and they support the first access technology, wherein the first access technology is higher than the access technology supported by the PLMN currently connected to by the terminal device.

[0289] For a detailed explanation of the first parameter, the first PLMN, the second PLMN, and the third PLMN, please refer to [link / reference needed]. Figure 2 The relevant descriptions in step S202 of the illustrated embodiment will not be repeated here.

[0290] If a PLMN with the second priority successfully connects, the terminal device can execute step S306.

[0291] If all attempts to connect to the PLMN with the second priority fail, the terminal device can execute step S310.

[0292] Step S310: The terminal device resides in the currently accessed PLMN.

[0293] After performing step S310, the terminal device can perform step S307.

[0294] For example, taking the case where the first parameter at least includes an access technology, step S305 will be further explained. Figure 4 As shown, step S305 may include the following steps:

[0295] Step S3051: The terminal device determines whether there is a PLMN that supports the third access technology among the PLMNs with the highest priority.

[0296] The third access technology is the highest access technology supported by the terminal device, excluding the fourth access technology. The fourth access technology is the access technology used by the terminal device when attempting to access a PLMN with the highest priority.

[0297] If so (i.e., if there is a PLMN that supports the third access technology among the PLMNs with the highest priority), the terminal device can execute step S3052.

[0298] If not (i.e., if there is no PLMN supporting the third access technology among the PLMNs with the highest priority), the terminal device can execute step S304.

[0299] Step S3052: The terminal device selects a PLMN that supports third access technology to attempt to access.

[0300] If there is only one PLMN that supports third-party access technology, the terminal device can try to connect to that PLMN.

[0301] Optionally, if there are multiple PLMNs that support third access technology, the terminal device may randomly select one of the multiple PLMNs that support third access technology to connect to. If the randomly selected PLMN fails to connect, the terminal device may continue to randomly select another PLMN from the multiple PLMNs that support third access technology that have not yet been tried to connect to.

[0302] Optionally, if multiple PLMNs support the third access technology, the terminal device will prioritize accessing the first PLMN among the multiple PLMNs according to the parameters other than the access technology in the first parameter. If access to the first PLMN fails, the terminal device will attempt to access the second and / or third PLMN (if a third PLMN exists). The technical logic here can be found in [link to relevant documentation]. Figure 2 The implementation method of prioritizing access to the first PLMN in step S201 of the illustrated embodiment when the first parameter includes parameters other than the access technology will not be described again here.

[0303] If a PLMN that supports third access technology successfully connects, the terminal device can execute step S306.

[0304] If all attempts to access the PLMN that support the third access technology fail, the terminal device can execute step S3051.

[0305] For example, taking the case where the first parameter at least includes an access technology, step S309 will be further explained. Figure 5 As shown, step S309 may include the following steps:

[0306] Step S3091: The terminal device determines whether there is a PLMN that supports the fifth access technology among the PLMNs with the second priority.

[0307] Among them, the fifth access technology simultaneously meets the following conditions a and b:

[0308] Condition a. The fifth access technology is the highest access technology among the terminal device's access technologies, excluding the sixth access technology. The sixth access technology is the access technology used by the terminal device when attempting to access a PLMN with a priority of second priority.

[0309] Condition b. The fifth access technology is superior to the access technology of the PLMN currently connected to the terminal device.

[0310] If so (i.e., if there is a PLMN supporting the fifth access technology in the PLMN with the second priority), the terminal device executes step S3092.

[0311] If not (i.e., if there is no PLMN supporting the fifth access technology among the PLMNs with the second priority), the terminal device executes step S310.

[0312] Step S3092: The terminal device selects a PLMN that supports the fifth access technology to attempt to access it.

[0313] If there is only one PLMN that supports the fifth access technology, the terminal device can try to connect to that PLMN.

[0314] Optionally, if there are multiple PLMNs that support the fifth access technology, the terminal device may randomly select one of the multiple PLMNs that support the fifth access technology to connect to. If the randomly selected PLMN fails to connect, the terminal device may continue to randomly select another PLMN from the multiple PLMNs that support the fifth access technology that have not yet been tried to connect to.

[0315] Optionally, if multiple PLMNs support the fifth access technology, the terminal device will prioritize accessing the first PLMN among the multiple PLMNs according to the parameters other than the access technology in the first parameter. If access to the first PLMN fails, the terminal device will attempt to access the second and / or third PLMN (if a second and third PLMN exist). The technical logic here can be found in [reference needed]. Figure 2 The implementation method of prioritizing access to the first PLMN in step S201 of the illustrated embodiment when the first parameter includes parameters other than the access technology will not be described again here.

[0316] If a PLMN that supports the fifth access technology successfully connects, the terminal device can execute step S306.

[0317] If all attempts to access the PLMN that support the fifth access technology fail, the terminal device can execute step S3091.

[0318] It should be noted that, Figures 3 to 5For explanations of "PLMN access successful" and "PLMN access failed" mentioned in the illustrated embodiments, please refer to [link / reference]. Figure 2 The relevant descriptions in the illustrated embodiments will not be repeated here.

[0319] Combination Figures 3 to 5 It is understood that in roaming scenarios, after receiving the first information containing the PLMN priority, the terminal device can prioritize requesting registration from the PLMN with a higher priority than the currently accessed PLMN among the candidate PLMNs obtained from the network search. Furthermore, among multiple PLMNs with a higher priority than the currently accessed PLMN, the terminal device can prioritize requesting registration from the PLMN whose supported access technology is the highest access technology supported by the terminal, thereby improving the user experience in roaming scenarios.

[0320] Furthermore, when a PLMN with a higher priority than the currently accessing PLMN fails to connect, the terminal device can request registration from the candidate PLMNs if the PLMN with the same priority as the currently accessing PLMN has an equal priority. Moreover, among multiple PLMNs with the same priority as the currently accessing PLMN, the terminal device can prioritize requesting registration from the PLMN whose supported access technology is the highest access technology supported by the terminal, and avoid requesting registration from PLMNs whose supported access technology is lower than that of the PLMN currently accessing the terminal, thereby improving the user experience in roaming scenarios.

[0321] In the above embodiments of the method provided in this application, the method provided in the embodiments of this application is described using the execution of a terminal device as an example. In this application, each embodiment can be implemented independently or in combination based on certain inherent relationships; in each embodiment, different implementation methods can be implemented in combination or independently. In order to realize the various functions in the method provided in the above embodiments of this application, the steps executed by the terminal device can be implemented by different functional entities that make up the terminal device.

[0322] The following describes the communication device provided in the embodiments of this application.

[0323] Figure 6 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application, such as... Figure 6 As shown, the communication device 60 includes a processing module 601 and a transceiver module 602. The transceiver module 602 can also be referred to as an interface, a communication interface, or a communication module, etc.

[0324] In some embodiments of this application, the communication device can be used to perform the actions performed by the terminal device or the first network device in the above method embodiments. Specifically, the transceiver module 602 is used to perform the transceiver-related operations performed by the terminal device or the first network device in the above method embodiments. For example, the transmitting end can be the device itself or a chip or functional module configurable in the device. The processing module 601 is used to perform the processing-related operations performed by the terminal device or the first network device in the above method embodiments. The processing module 601 can perform the corresponding operations by calling a computer program or by performing the corresponding operations through corresponding hardware circuits. The transceiver module 602 can perform transceiver operations independently or under the control of the processing module 601.

[0325] For example, Figure 6 The communication device 60 shown can be a terminal device or a component in a terminal device as described in the above method embodiments. The transceiver module 602 in the communication device 60 can perform the following operations:

[0326] The transceiver module 602 is used to receive first information, wherein the first information includes a list of public land mobile networks (PLMNs), at least two PLMNs in the PLMN list have the same priority, and the PLMNs in the PLMN list are PLMNs that allow terminal devices to roam and access.

[0327] The transceiver module 602 is also configured to send a first message to the first PLMN among the at least two PLMNs according to the first parameters of the at least two PLMNs, wherein the first parameters include one or more of the supported access technologies and supported service types, and the first message is used to request registration.

[0328] In one alternative implementation, the first information also includes:

[0329] Priority or indication information for at least two PLMNs, where the indication information is used to indicate that at least two PLMNs have the same priority.

[0330] In another alternative implementation, the first information may also include one or more of the following:

[0331] At least two PLMN-supported access technologies;

[0332] At least two PLMN-supported service types;

[0333] Predicted duration of at least two PLMNs being in a congested state.

[0334] In another alternative implementation, at least two PLMNs satisfy one or more of the following conditions:

[0335] At least two PLMNs must have the same roaming rates;

[0336] At least two PLMNs support the same number of service types.

[0337] In another alternative implementation, the first parameter also includes one or more of the following information:

[0338] Signal quality;

[0339] Predicted duration of congestion.

[0340] In another alternative implementation, the first PLMN satisfies one or more of the following conditions:

[0341] The first PLMN supports the first access technology, which is an access technology supported by the terminal equipment.

[0342] The first PLMN supports the first access technology, which is superior to the access technology of the PLMN currently connected to by the terminal device.

[0343] The first PLMN supports the first access technology, wherein the first access technology is the highest access technology supported by at least two PLMNs;

[0344] The first PLMN's access technology is an access technology supported by the terminal equipment.

[0345] The priority of the first PLMN is equal to or higher than the priority of the PLMN currently connected to the terminal device.

[0346] The access technology of the first PLMN is superior to the access technology of the PLMN currently connected to by the terminal device.

[0347] The first PLMN supports service types that meet the service preferences of terminal devices;

[0348] The first PLMN's access technology is the PLMN with the highest access technology among at least two PLMNs;

[0349] The first PLMN is the PLMN that supports the most service types among at least two PLMNs;

[0350] The first PLMN is the PLMN with the highest signal quality among at least two PLMNs;

[0351] The prediction duration of the first PLMN being in a congested state is no greater than the first preset threshold.

[0352] In another alternative implementation, before sending the first request message to the first PLMN of at least two PLMNs based on the first parameters of at least two PLMNs:

[0353] The processing module 601 is used to obtain candidate PLMNs by searching the network, wherein the candidate PLMNs include at least two PLMNs.

[0354] In another alternative implementation, the first PLMN has a higher priority than the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the first PLMN has a priority equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology of the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0355] The first parameter includes the access technology. Specifically, in sending a first message to the first PLMN among at least two PLMNs based on the first parameters of at least two PLMNs, the transceiver module 602 is used for:

[0356] If none of the at least two PLMNs support the first access technology and the second access technology, then a first message is sent to the first PLMN based on the first access technology, wherein the second access technology is superior to the first access technology and is an access technology supported by the terminal device.

[0357] In another alternative implementation, the first PLMN has a higher priority than the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the first PLMN has a priority equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology of the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0358] The at least two PLMNs also include a second PLMN. The first parameters include access technology and signal quality. Specifically, the transceiver module 602 is used to send a first message to the first PLMN of the at least two PLMNs based on the first parameters of the at least two PLMNs.

[0359] If both the first PLMN and the second PLMN support the first access technology, and the signal quality of the first PLMN is higher than that of the second PLMN, then the first message is sent to the first PLMN based on the first access technology.

[0360] In another alternative implementation, the priority of the first PLMN is greater than or equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the priority of the first PLMN is equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology supported by the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0361] The at least two PLMNs also include a second PLMN. The first parameter includes the access technology and supported service types. Specifically, the transceiver module 602 is used to send a first message to the first PLMN among the at least two PLMNs based on the first parameter of the at least two PLMNs.

[0362] If both the first PLMN and the second PLMN support the first access technology, and the service type supported by the first PLMN meets the service preferences of the terminal device, while the service type supported by the second PLMN does not meet the service preferences of the terminal device, then a first message is sent to the first PLMN based on the first access technology; or,

[0363] If both the first PLMN and the second PLMN support the first access technology, and the number of service types supported by the first PLMN is greater than the number of service types supported by the second PLMN, then a first message is sent to the first PLMN based on the first access technology.

[0364] In another alternative implementation, the priority of the first PLMN is greater than or equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the priority of the first PLMN is equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology supported by the PLMN currently accessed by the terminal device and is an access technology supported by the terminal device.

[0365] The at least two PLMNs also include a second PLMN. The first parameter includes the access technology and the predicted duration of the congestion state. Specifically, the transceiver module 602 is used to send a first message to the first PLMN among the at least two PLMNs based on the first parameters of the at least two PLMNs.

[0366] If both the first PLMN and the second PLMN support the first access technology, and the predicted duration of the first PLMN being in a congested state is less than the predicted duration of the second PLMN being in a congested state, then a first message is sent to the first PLMN based on the first access technology.

[0367] In yet another alternative implementation, the transceiver module 602 is also used for:

[0368] Receive a second message, wherein the second message is used in response to the first message, and the second message includes the service types supported by the first PLMN;

[0369] If the service types supported by the first PLMN do not meet the service preferences of the terminal device, a third message is sent to the second PLMN, wherein the third message is used to request registration.

[0370] In yet another alternative implementation, the transceiver module 602 is also used for:

[0371] Receive a second message, wherein the second message is used in response to the first message, and the second message includes the predicted duration of the first PLMN being in a congested state;

[0372] If the predicted duration of the congestion state of the first PLMN is greater than the first preset threshold, a third message is sent to the second PLMN, wherein the third message is used to request registration.

[0373] Reuse Figure 6 In other embodiments of this application, exemplarily, Figure 6 The communication device 60 shown can be the first network device or a component in the first network device described in the above method embodiment. The processing module 601 and the transceiver module 602 in the communication device 60 can respectively perform the following operations:

[0374] The processing module 601 is used to determine the first information, wherein the first information includes a PLMN list, and there are at least two PLMNs with the same priority in the PLMN list;

[0375] The transceiver module 602 is used to send the first information.

[0376] In one alternative implementation, the first information further includes:

[0377] Priority or indication information for at least two PLMNs, where the indication information is used to indicate that at least two PLMNs have the same priority.

[0378] In one alternative implementation, in determining the first information, the processing module 601 is specifically configured to:

[0379] First information is determined according to a first strategy, wherein the first strategy defines one or more of the following information:

[0380] If PLMNs have the same roaming rates, they have the same priority; and the lower the roaming rate of a PLMN, the higher its priority.

[0381] If a PLMN supports the same number of service types, it has the same priority; however, the more service types a PLMN supports, the higher its priority.

[0382] In one alternative implementation, the first information further includes one or more of the following:

[0383] Access technologies for at least two PLMNs;

[0384] At least two PLMN-supported service types;

[0385] Predicted duration of at least two PLMNs being in a congested state.

[0386] The specific descriptions of the transceiver module 602 and the processing module 601 shown in the above embodiments are merely examples. For the specific functions or execution steps of the transceiver module 602 and the processing module 601, please refer to the above method embodiments, which will not be described in detail here.

[0387] The communication device according to the embodiments of this application has been described above. The following describes the possible product forms of the communication device. Any device possessing the above-described... Figure 6 Any form of product that incorporates the functionality of the aforementioned communication device falls within the protection scope of the embodiments of this application.

[0388] The following description is merely an example and does not limit the product form of the communication device in the embodiments of this application to this.

[0389] In one possible implementation, Figure 6 In the communication device 60 shown, the processing module 601 can be one or more processors, and the transceiver module 602 can be a transceiver, or the transceiver module 602 can also be a transmitting module and a receiving module. The transmitting module can be a transmitter, and the receiving module can be a receiver. The transmitting module and the receiving module are integrated into one device, such as a transceiver. In the embodiments of this application, the processor and the transceiver can be coupled, etc., and the connection method between the processor and the transceiver is not limited in the embodiments of this application. In the process of executing the above method, the process of sending information in the above method can be the process of the processor outputting the above information. When outputting the above information, the processor outputs the above information to the transceiver so that the transceiver can transmit it. After the above information is output by the processor, it may need to undergo other processing before reaching the transceiver. Similarly, the process of receiving information in the above method can be the process of the processor receiving the input above information. When the processor receives the input information, the transceiver receives the above information and inputs it into the processor. Furthermore, after the transceiver receives the above information, the above information may need to undergo other processing before being input into the processor.

[0390] like Figure 7As shown, the communication device 70 includes one or more processors 702 and one or more memories 701. Exemplarily, the memory 701 is used to store program instructions and / or data. The processor 702 is used to execute the processing-related functions or steps implemented by the terminal device or the first network device in the above method embodiments. Detailed descriptions can be found in the method embodiments shown above, and will not be repeated here.

[0391] Optionally, the memory 701 and the processor 702 are coupled. The coupling in this embodiment is an indirect coupling or communication connection between devices, units, or modules, which can be electrical, mechanical, or other forms, used for information exchange between devices, units, or modules. Optionally, the processor 702 and the memory 701 operate collaboratively. The processor 702 can execute program instructions stored in the memory 701. Optionally, at least one of the above-mentioned one or more memories 701 is included in the processor 702.

[0392] Optionally, the communication device 70 may further include one or more transceivers 703, which are used to perform the transmission and reception related functions or steps implemented by the terminal device or the first network device in the above method embodiments. For details, please refer to the method embodiments shown above, which will not be described in detail here.

[0393] The descriptions of the relevant steps and information in the above embodiments can be found in the descriptions of the method embodiments above, and will not be detailed here.

[0394] This application embodiment does not limit the specific connection medium between the memory 701, processor 702, and transceiver 703 described above. This application embodiment... Figure 7 The memory 701, processor 702, and transceiver 703 are connected via a bus 704. Figure 7 The connections between other components are shown in bold and are for illustrative purposes only, not as limiting information. The bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, Figure 7 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0395] In the embodiments of this application, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this application. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of this application can be directly manifested as being executed by a hardware processor, or being executed by a combination of hardware and software modules within the processor.

[0396] In this application embodiment, the memory may include, but is not limited to, non-volatile memory such as hard disk drive (HDD) or solid-state drive (SSD), random access memory (RAM), erasable programmable read-only memory (EPROM), read-only memory (ROM), or compact disc read-only memory (CD-ROM), etc. Memory is any storage medium capable of carrying or storing program code in the form of instructions or data structures, and capable of being read and / or written by a computer (such as the communication device shown in this application), but is not limited to this. The memory in this application embodiment may also be a circuit or any other device capable of implementing storage functions, used to store program instructions and / or data.

[0397] The processor 702 is primarily used to process communication protocols and data, control the entire communication device, execute software programs, and process the data from those programs. The memory 701 is primarily used to store software programs and data. The transceiver 703 may include control circuitry and an antenna. The control circuitry is primarily used for converting baseband signals to radio frequency signals and processing radio frequency signals. The antenna is primarily used for transmitting and receiving radio frequency signals in the form of electromagnetic waves. Input / output devices, such as touchscreens, displays, and keyboards, are primarily used to receive user input data and output data to the user.

[0398] When the communication device is powered on, the processor 702 can read the software program in the memory 701, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted wirelessly, the processor 702 performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency (RF) circuit. The RF circuit processes the baseband signal and transmits the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the communication device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor 702. The processor 702 converts the baseband signal into data and processes the data.

[0399] In another implementation, the radio frequency circuitry and antenna can be set up independently of the processor that performs baseband processing. For example, in a distributed scenario, the radio frequency circuitry and antenna can be arranged remotely, independent of the communication device.

[0400] The communication device shown in the embodiments of this application may also have a higher... Figure 7This application does not limit the use of other components or other related elements. The methods performed by the processor and transceiver shown above are merely examples; the specific steps performed by the processor and transceiver can be found in the methods described above.

[0401] In another possible implementation Figure 6 In the communication device shown, the processing module 601 can be one or more logic circuits, and the transceiver module 602 can be an input / output interface, or a communication interface, or an interface circuit, or an interface, etc. Alternatively, the transceiver module 602 can also be a transmitting module and a receiving module; the transmitting module can be an output interface, and the receiving module can be an input interface, integrated into one module, such as an input / output interface. Figure 8 As shown, Figure 8 The communication device 80 shown includes a logic circuit 801 and an interface 802. That is, the processing module 601 can be implemented using the logic circuit 801, and the transceiver module 602 can be implemented using the interface 802. The logic circuit 801 can be a chip, processing circuit, integrated circuit, or system-on-chip (SoC) chip, etc., and the interface 802 can be a communication interface, input / output interface, pins, etc. For example, Figure 8 Taking the aforementioned communication device as an example, the chip includes a logic circuit 801 and an interface 802.

[0402] In this embodiment, the logic circuit and the interface can also be coupled to each other. The specific connection method of the logic circuit and the interface is not limited in this embodiment. For example, the logic circuit 801 can be used to execute the processing-related functions or steps implemented by the terminal device or the first network device in the above method embodiments; for details, please refer to the method embodiments shown above. The interface 802 can be used to execute the transmission-reception-related functions or steps implemented by the terminal device or the first network device in the above method embodiments; for details, please refer to the method embodiments shown above.

[0403] The above description of the communication device is merely an example; for... Figure 8 For a detailed description of the communication device shown, please refer to the method embodiments above or Figure 6 or Figure 7 This will not be elaborated upon here.

[0404] The communication device shown in the embodiments of this application can implement the method provided in the embodiments of this application in hardware form, or it can implement the method provided in the embodiments of this application in software form, etc., and the embodiments of this application do not limit it in this way.

[0405] The descriptions of relevant steps and information in the above embodiments can be found in the descriptions of the method embodiments above, and will not be detailed here. For Figure 8 For specific implementations of the various embodiments shown, please refer to the above embodiments, which will not be described in detail here.

[0406] This application also provides a communication system, which includes a first communication device and a second communication device. The first communication device is used to perform all or part of the operations of the terminal device in any of the foregoing method embodiments, and the second communication device is used to perform all or part of the operations of the first network device in any of the foregoing method embodiments.

[0407] In addition, this application also provides a computer program for implementing the operations and / or processes performed by a terminal device or a first network device in the method provided in this application.

[0408] This application also provides a computer-readable storage medium storing computer code, which, when executed on a computer, causes the computer to perform the operations and / or processes performed by a terminal device or a first network device in the method provided in this application.

[0409] This application also provides a computer program product, which includes computer code or a computer program that, when run on a computer, causes the operations and / or processes performed by a terminal device or a first network device in the method provided in this application to be executed.

[0410] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, or it may be an electrical, mechanical, or other form of connection.

[0411] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the technical effects of the solutions provided in the embodiments of this application.

[0412] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0413] If the integrated module is implemented as a software functional module 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 application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a readable storage medium and includes 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 described in the various embodiments of this application. The aforementioned readable 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.

[0414] In this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0415] Furthermore, unless otherwise stated, the use of ordinal numbers such as "first" and "second" in the embodiments of this application is for distinguishing multiple objects, and is not for limiting the order, timing, priority or importance of multiple objects, such as first information and first message.

[0416] The above description is merely a specific embodiment of this application, but the scope of protection of this 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 application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method, characterized in that, Applied to a terminal device, the method includes: Receive first information, wherein the first information includes a list of public land mobile networks (PLMNs), wherein at least two PLMNs in the PLMN list have the same priority, and the PLMNs in the PLMN list are PLMNs that allow the terminal device to roam and access. Based on the first parameters of the at least two PLMNs, a first message is sent to the first PLMN of the at least two PLMNs, wherein the first parameters include one or more of the supported access technologies and supported service types, and the first message is used to request registration.

2. The method according to claim 1, characterized in that, The first information also includes: The priority or indication information of the at least two PLMNs, wherein the indication information is used to indicate that the at least two PLMNs have the same priority.

3. The method according to claim 1 or 2, characterized in that, The first information also includes one or more of the following: The access technologies supported by the at least two PLMNs; The service types supported by at least two PLMNs; The predicted duration of at least two PLMNs being in a congested state.

4. The method according to any one of claims 1-3, characterized in that, The at least two PLMNs satisfy one or more of the following conditions: The roaming rates are the same; The number of supported business types is the same.

5. The method according to any one of claims 1-4, characterized in that, The first parameter also includes one or more of the following information: Signal quality; Predicted duration of congestion.

6. The method according to any one of claims 1-5, characterized in that, The first PLMN satisfies one or more of the following conditions: The first PLMN supports a first access technology, wherein the first access technology is an access technology supported by the terminal device; The first PLMN supports a first access technology, wherein the first access technology is superior to the access technology of the PLMN currently accessed by the terminal device; The first PLMN supports a first access technology, wherein the first access technology is the highest access technology supported by the at least two PLMNs; The priority of the first PLMN is equal to or higher than the priority of the PLMN currently connected to by the terminal device; The service types supported by the first PLMN meet the service preferences of the terminal device. The first PLMN is the PLMN that supports the most service types among the at least two PLMNs; The first PLMN is the PLMN with the highest signal quality among the at least two PLMNs; The prediction duration of the first PLMN being in a congested state is no greater than a first preset threshold.

7. The method according to any one of claims 1-6, characterized in that, Before sending a first request message to the first PLMN among the at least two PLMNs based on the first parameters of the at least two PLMNs, the method further includes: Candidate PLMNs are obtained by searching the network, wherein the candidate PLMNs include the at least two PLMNs.

8. The method according to any one of claims 1-7, characterized in that, The first PLMN has a higher priority than the PLMN currently connected to by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the first PLMN has a higher priority than the PLMN currently connected to by the terminal device, and the first access technology supported by the first PLMN is a higher access technology than the PLMN currently connected to by the terminal device and is an access technology supported by the terminal device. The first parameter includes the access technology, and the step of sending a first message to the first PLMN among the at least two PLMNs according to the first parameters of the at least two PLMNs includes: If none of the at least two PLMNs supports the first access technology and the second access technology, then the first message is sent to the first PLMN based on the first access technology, wherein the second access technology is superior to the first access technology and is an access technology supported by the terminal device.

9. The method according to any one of claims 1-7, characterized in that, The first PLMN has a higher priority than the PLMN currently connected to by the terminal device, and the first access technology supported by the first PLMN is an access technology supported by the terminal device; or, the first PLMN has a higher priority than the PLMN currently connected to by the terminal device, and the first access technology supported by the first PLMN is a higher access technology than the PLMN currently connected to by the terminal device and is an access technology supported by the terminal device. The at least two PLMNs further include a second PLMN. The first parameter includes access technology and signal quality. Sending a first message to the first PLMN among the at least two PLMNs according to the first parameter of the at least two PLMNs includes: If both the first PLMN and the second PLMN support the first access technology, and the signal quality of the first PLMN is higher than that of the second PLMN, then the first message is sent to the first PLMN based on the first access technology.

10. The method according to any one of claims 1-7, characterized in that, The priority of the first PLMN is greater than or equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN belongs to the access technology supported by the terminal device. Alternatively, the priority of the first PLMN is equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology of the PLMN currently accessed by the terminal device and belongs to the access technology supported by the terminal device. The at least two PLMNs further include a second PLMN. The first parameter includes the access technology and supported service types. Sending a first message to the first PLMN among the at least two PLMNs according to the first parameter of the at least two PLMNs includes: If both the first PLMN and the second PLMN support the first access technology, and the service type supported by the first PLMN meets the service preferences of the terminal device, while the service type supported by the second PLMN does not meet the service preferences of the terminal device, then the first message is sent to the first PLMN based on the first access technology. or, If both the first PLMN and the second PLMN support the first access technology, and the number of service types supported by the first PLMN is greater than the number of service types supported by the second PLMN, then the first message is sent to the first PLMN based on the first access technology.

11. The method according to any one of claims 1-7, characterized in that, The priority of the first PLMN is greater than or equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN belongs to the access technology supported by the terminal device. Alternatively, the priority of the first PLMN is equal to the priority of the PLMN currently accessed by the terminal device, and the first access technology supported by the first PLMN is higher than the access technology of the PLMN currently accessed by the terminal device and belongs to the access technology supported by the terminal device. The at least two PLMNs further include a second PLMN. The first parameter includes the predicted duration of the access technology and congestion state. Sending a first message to the first PLMN among the at least two PLMNs based on the first parameters of the at least two PLMNs includes: If both the first PLMN and the second PLMN support the first access technology, and the predicted duration of the first PLMN being in a congested state is less than the predicted duration of the second PLMN being in a congested state, then a first message is sent to the first PLMN based on the first access technology.

12. The method according to any one of claims 9-11, characterized in that, The method further includes: Receive a second message, wherein the second message is used to respond to the first message, and the second message includes the service types supported by the first PLMN; If the service type supported by the first PLMN does not meet the service preferences of the terminal device, a third message is sent to the second PLMN, wherein the third message is used to request registration.

13. The method according to any one of claims 9-11, characterized in that, The method further includes: Receive a second message, wherein the second message is used in response to the first message, and the second message includes the predicted duration of the first PLMN being in a congested state; If the predicted duration of the congestion state of the first PLMN is greater than a first preset threshold, a third message is sent to the second PLMN, wherein the third message is used to request registration.

14. A communication method, characterized in that, Applied to a first network device, the method includes: First information is determined, wherein the first information includes a PLMN list, wherein at least two PLMNs in the PLMN list have the same priority, and the PLMNs in the PLMN list are PLMNs that allow terminal devices to roam and access. Send the first message.

15. The method according to claim 14, characterized in that, The first information also includes: The priority or indication information of the at least two PLMNs, wherein the indication information is used to indicate that the at least two PLMNs have the same priority.

16. The method according to claim 14 or 15, characterized in that, The determination of the first information includes: The first information is determined according to a first strategy, wherein the first strategy defines one or more of the following information: If PLMNs have the same roaming rates, they have the same priority; and the lower the roaming rate of a PLMN, the higher its priority. If a PLMN supports the same number of service types, it has the same priority; however, the more service types a PLMN supports, the higher its priority.

17. The method according to any one of claims 14-16, characterized in that, The first information also includes one or more of the following: The access technology for at least two PLMNs; The service types supported by at least two PLMNs; The predicted duration of at least two PLMNs being in a congested state.

18. A communication device, characterized in that, The communication device includes a module for performing the method as described in any one of claims 1-17; or, the communication device includes a processor configured to cause the communication device to implement the method as described in any one of claims 1-17.

19. A communication device, characterized in that, The communication device includes logic circuitry and an interface, the interface being used for inputting and / or outputting information, and the logic circuitry being used to enable the communication device to implement the method as described in any one of claims 1-17.

20. A communication system, characterized in that, The communication device includes a first communication device and a second communication device, wherein the first communication device is used to perform the method as described in any one of claims 1-13, and the second communication device is used to perform the method as described in any one of claims 14-17.

21. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program, which, when executed, performs the method as described in any one of claims 1-17.

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