Network selection method, terminal device, computer-readable storage medium and chip

Abstract

The present application relates to the technical field of communications. Provided are a network selection method, a terminal device, a computer-readable storage medium and a chip. The method is applied to a terminal device, wherein a SIM card installed in the terminal device supports a first VPLMN and a second VPLMN, which are different from each other. The method comprises: successfully performing registration with a first network of a first network standard of a first VPLMN; detecting that the first network cannot provide a service to a terminal device, and searching for a second network of a second network standard of a second VPLMN, wherein the first network standard is the same as the second network standard, or the second network standard is higher than the first network standard; and after the second network is found, performing registration with the second network. In the technical solutions provided in the embodiments of the present application, after being disconnected from a network in a roaming scenario, a terminal device can be preferentially connected to high-standard networks of other VPLMNs, so as to avoid the downgrade of the network of the terminal device from a higher standard to a lower standard as much as possible, thereby ensuring the communication quality of the terminal device, and improving the user experience.

Description

Network selection method, terminal device, computer readable storage medium and chip

[0001] The present application claims priority to the Chinese patent application No. 202410430510.6, filed on April 10, 2024, and entitled "Network selection method, terminal device, computer readable storage medium and chip", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, in particular to a network selection method, a terminal device, a computer readable storage medium and a chip. BACKGROUND

[0003] At present, a terminal device needs to connect a roaming network to use voice, data, multimedia and other network services when roaming, and the roaming network is a visited public land mobile network (VPLMN).

[0004] The terminal device usually preferentially registers a high-mode network of the VPLMN, and marks the VPLMN as a register PLMN (RPLMN) after successful registration. In the subsequent process, if the terminal device detects that the high-mode network of the RPLMN cannot be used temporarily, the terminal device will automatically fall back to a low-mode network of the RPLMN. It can be understood that, due to the change of the network mode from high to low, the terminal device cannot use the high-speed and high-quality voice call service provided by the high-mode network, the communication quality is poor, and the user experience is seriously affected. SUMMARY

[0005] The present application provides a network selection method, a terminal device, a computer readable storage medium and a chip, which are used to solve the problem that the call quality of the terminal device may be poor after the terminal device is disconnected in a roaming area in the prior art.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a network selection method, which is applied to a terminal device, the terminal device is installed with a subscriber identity module (SIM) card, the SIM card supports a first VPLMN and a second VPLMN, and the method specifically comprises: successfully registering a first network of a first network mode of the first VPLMN; detecting that the first network cannot provide services to the terminal device, and searching for a second network of a second network mode of the second VPLMN; wherein the first network mode is the same as the second network mode, or the second network mode is higher than the first network mode; and registering the second network after searching for the second network.

[0008] By the network selection method provided in the embodiments of the present application, after the terminal device is disconnected from the network in the roaming scenario, the terminal device can preferentially connect to the high-standard network of other VPLMN, so as to avoid the network of the terminal device from dropping from the high standard to the low standard as much as possible, thereby ensuring the communication quality of the terminal device and improving the user experience.

[0009] In some embodiments, the terminal device detecting that the first network cannot provide services for the terminal device includes: the terminal device failing to search for a cell meeting a registration condition in the first network; or the terminal device receiving first indication information sent by the network device, the first indication information being used to indicate that the terminal device cannot use the first network temporarily.

[0010] In other words, the terminal device can determine whether the first network can provide services by itself, or can determine whether the first network can provide services according to the notification of the network device.

[0011] In some embodiments, the coverage area of the first network includes a first location area and a second location area which are different and partially overlapped; and then, the terminal device successfully registering the first network of the first network standard of the first VPLMN includes: the terminal device successfully registering a first cell in the first location area.

[0012] In some embodiments, after the terminal device searches for the second network of the second network standard of the second VPLMN, the terminal device registers the second network, specifically including: if the terminal device fails to search for a second cell meeting a registration condition in the second location area, the terminal device searches for the second network of the second network standard of the second VPLMN; and after searching for the second network, the terminal device registers the second network. Or, if the terminal device searches for the second cell meeting the registration condition in the second location area and fails to register the second cell, the terminal device searches for the second network of the second network standard of the second VPLMN; and after searching for the second network, the terminal device registers the second network.

[0013] By the network selection method provided in the embodiments of the present application, the terminal device can continue to attempt to register the first network of the first network standard of the RPLMN in other location areas, so as to ensure that the terminal device still camps on the first network as much as possible, avoid the terminal device from continuing to perform PLMN search and switching, and improve the network recovery speed of the terminal device.

[0014] In some embodiments, after the terminal device successfully registers the first network of the first network standard of the first VPLMN, the method further includes: marking the first VPLMN as the RPLMN; and after failing to register the second network, registering a third network of a third network standard of the RPLMN; wherein the third network standard is lower than the first network standard.

[0015] By the network selection method provided in this embodiment, the terminal device preferentially selects a network of a lower network standard (e.g., 3G) of the RPLMN to avoid performing PLMN search and switching again and improve the network recovery speed of the terminal device, in a case where the other VPLMN cannot guarantee that the network standard of the network selected by the terminal device is not reduced.

[0016] In some embodiments, the method further includes: after the registration of the third network fails, registering a fourth network of the third network standard of the second VPLMN.

[0017] By the method provided in this embodiment, the terminal device can search for a network of a lower network standard (e.g., 3G) in other VPLMN when the network of the lower network standard (e.g., 3G) of the RPLMN cannot be searched, so as to guarantee that the network of the terminal device does not fall back to a lower standard (e.g., 2G).

[0018] In some embodiments, the registering of the second network of the second network standard of the second VPLMN includes: obtaining frequency point information of the second network; searching for a target cell of the second network that meets a registration condition according to the frequency point information; and registering the target cell.

[0019] For example, the frequency point information is historical frequency point information of the second network stored locally; or the frequency point information is historical frequency point information of the second network obtained from a server, and the historical frequency point information is uploaded by the terminal device and / or other terminal devices.

[0020] By the method provided in this embodiment, the terminal device can avoid searching for a target cell on the second network as much as possible, improve the cell search rate, and improve the network recovery speed of the terminal device.

[0021] In a second aspect, the embodiments of the present application further provide a network selection device, which is applied to a terminal device, a SIM card of the terminal device supports a first VPLMN and a second VPLMN, and the device specifically includes:

[0022] The network registration module is configured to register a first network of a first network standard of the first VPLMN.

[0023] The network detection module is configured to, after the registration of the first network succeeds, detect whether the first network can provide services to the terminal device.

[0024] The network registration module is further configured to, after the first network cannot provide services to the terminal device and a second network of a second network standard of the second VPLMN is searched, register the second network. The first network standard is the same as the second network standard, or the second network standard is higher than the first network standard.

[0025] In a third aspect, an embodiment of the present application provides a terminal device, which comprises a memory, a processor, and a computer program stored in the memory and capable of running on the processor, and the processor implements the network selection method shown in the first aspect when executing the computer program.

[0026] In a fourth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program, when executed by a processor, implements the network selection method shown in the first aspect.

[0027] In a fifth aspect, an embodiment of the present application provides a chip, which comprises a processor and a memory, and the memory stores a computer program, and the computer program, when executed by the processor, implements the network selection method shown in the first aspect.

[0028] In a sixth aspect, an embodiment of the present application provides a computer program product, which comprises a computer program, and when the computer program is run by an electronic device, the electronic device implements the network selection method shown in the first aspect.

[0029] It can be understood that the beneficial effects of the second aspect to the sixth aspect can be referred to the related description in the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a structural schematic diagram of a communication system provided by an embodiment of the present application;

[0031] FIG. 2 is a schematic flowchart of a network selection method provided by an embodiment of the present application;

[0032] FIG. 3 is a schematic diagram of a network selection scenario provided by an embodiment of the present application;

[0033] FIG. 4 is a schematic flowchart of a network selection method provided by another embodiment of the present application;

[0034] FIG. 5 is a structural schematic diagram of a network selection apparatus 500 provided by an embodiment of the present application;

[0035] FIG. 6 is a structural schematic diagram of a chip provided by an embodiment of the present application. DETAILED DESCRIPTION

[0036] The technical solutions provided by the embodiments of the present application will be described below with reference to the accompanying drawings.

[0037] It should be understood that, in the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" herein only describes the relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone.

[0038] In the embodiments, the terms "first", "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments, unless otherwise specified, the meaning of "multiple" is two or more.

[0039] In order to facilitate description and understanding, first, the basic concepts related to the embodiments of the present application are explained.

[0040] (1) PLMN

[0041] The public land mobile network (PLMN) is a network operated by an operator to provide land mobile communication services to the public. Each operator has one or more PLMNs.

[0042] The PLMN is identified by a mobile country code (MCC) and a mobile network code (MNC). For ease of description, the PLMN can be represented as PLMN=MCC+MNC. Among them, MCC is used to uniquely identify the country to which the public land mobile network belongs, for example, the MCC of China is 460, the MCC of Thailand is 520, and the MCC of Singapore is 525. MNC is used to identify the network in the corresponding country. An operator can use one or more MNCs to identify its own network. For example, the MNCs of China Mobile network include 00, 02, 04 and 07, the MNCs of China Unicom network include 01, 06 and 09, the MNCs of China Telecom network include 03, 05 and 11, and the MNCs of China Railcom network include 20. It can be understood that the PLMN of China Mobile network includes 46000, 46002, 46004 and 46007, and the PLMN of China Telecom network includes 46001, 46006 and 46009.

[0043] For a terminal device, it needs to maintain the following multiple types of PLMNs in the form of a list. Specifically, it includes:

[0044] RPLMN (register PLMN): the PLMN registered by the terminal device before the last power-on or disconnection, stored in the SIM card or memory of the terminal device.

[0045] EPLMN (equivalent PLMN): the PLMN in the same position as the PLMN currently selected by the terminal device, with the same priority. The EPLMN is configured on the mobile switching center (MSC) or mobile management entity (MME) of the core network, and is the PLMN equivalent to the HPLMN of the current network. It can be understood that if the user is in the home country, the EPLMN is equal to the EHPLMN. If in the roaming country, the EPLMN is not equal to the EHPLMN.

[0046] HPLMN (home PLMN): the PLMN corresponding to the international mobile subscriber identification number (IMSI) in the universal subscriber identification module (SIM) card. There is only one HPLMN for a registered user.

[0047] EHPLMN (equivalent home PLMN): the home PLMN in the same position as the PLMN currently selected by the terminal device. In fact: EHPLMN and EPLMN are like the newly built 158 network of China Mobile, while the PLMN is like the original 135-139 network. The operator corresponding to the HPLMN may have different number segments, such as 46000, 46002, and 46007. 46002 is the EPLMN relative to 46000, and the EHPLMN is written into the SIM card when the operator burns the card.

[0048] UPLMN (user controlled PLMN): the PLMN selected by the terminal device when the user manually selects the network, and the UPLMN is stored in the SIM card.

[0049] OPLMN (operator controlled PLMN): the PLMN of the operator with which the operator has signed a roaming agreement, written into the SIM card by the operator when burning the card, as a suggestion for the user to select the network later.

[0050] VPLMN (visited PLMN, visited PLMN): the PLMN of the visited place of the terminal device. The VPLMN and the MCC / MNC part of the IMSI in the SIM card are different or all different. When the network of the mobile terminal loses coverage, a VPLMN will be selected.

[0051] In other words, the VPLMN is the roaming network of the terminal device. An operator usually signs one or more VPLMNs, for example, the VPLMNs signed by an operator include 52003, 52004, 52005, 52501, 52502, etc. When the local network of the mobile terminal loses coverage, that is, the terminal device cannot search for the HPLMN and EHPLMN signed by the SIM card, the terminal device will select a VPLMN to connect in the VPLMNs that it can search for, so as to enter the roaming state.

[0052] It should be noted that the VPLMN and the HPLMN usually belong to different operators, which can belong to different operators in different countries, or belong to operators in different regions of the same country. For example, the VPLMN belongs to operator A in country A, and the HPLMN belongs to operator B in country B. Or, the VPLMN belongs to operator A in country A, and the HPLMN belongs to operator C in country A.

[0053] APLMN (approve PLMN, captureable PLMN): the PLMN on which the terminal device can find at least one cell and read its PLMN identification information.

[0054] FPLMN (Forbidden PLMN, Forbidden PLMN): a PLMN that is prohibited to access. Usually, after the terminal is rejected when trying to access a certain PLMN, it will be added to the FPLMN list.

[0055] (2) Network mode

[0056] The network type refers to the type of network, which can also be referred to as a communication type or a standard. At present, the network type includes but is not limited to: the second generation mobile communication technology (2nd-generation wireless telephone technology, 2G), the third generation mobile communication technology (3rd-generation wireless telephone technology, 3G), the fourth generation mobile communication technology (4th-generation wireless telephone technology, 4G), the fifth generation mobile communication technology (5th-generation wireless telephone technology, 5G), and other future communication technologies (such as the sixth generation mobile communication technology (6th-generation wireless telephone technology, 6G)) and the like.

[0057] It should be noted that the generations of networks (i.e., 2G, 3G, 4G, 5G and 6G, etc.) are named according to the development history of the network, and each generation of communication network usually includes one or more types according to the different communication protocols used. For example, the 2G network includes: global system for mobile communications (global system of mobile communication, GSM) network, code division multiple access (code division multiple access, CDMA) network, etc. The 3G network includes: wideband code division multiple access (wideband code division multiple access, WCDMA) network, time division-synchronous CDMA (time division-synchronous CDMA, TD-SCDMA), universal mobile telecommunications system (universal mobile telecommunications system, UMTS), etc. The 4G network includes: long term evolution (long term evolution, LTE) network. The 5G network includes: new radio (new radio, NR) network, etc.

[0058] Generally, the higher the network type, the faster the network transmission rate, and the better the communication effect. For example, the communication effect of the 5G network is better than that of the 4G network, the communication effect of the 4G network is better than that of the 3G network, and the communication effect of the 3G network is better than that of the 2G network.

[0059] In this embodiment, the high network standard (referred to as high standard for short) and the low network standard (referred to as low standard for short) are relative concepts. For example, in the order of 6G, 5G, 4G, 3G and 2G, the network standards are successively lowered. Specifically, for 5G and 4G, 5G is the high standard, and 4G is the low standard. For 4G and 3G, 4G is the high standard, and 3G is the low standard. For 3G and 2G, 3G is the high standard, and 2G is the low standard.

[0060] (3) Roaming

[0061] Roaming refers to the function that, after a terminal device leaves the service area where it is registered and moves to another service area, the mobile communication system can still provide services to it. Alternatively, roaming refers to the function that, after a terminal device leaves its HPLMN and EHPLMN network, it communicates using other PLMN networks. Roaming can usually only be performed between domestic cities with network standard compatibility and networking, or between regions or countries that have signed a bilateral roaming agreement.

[0062] (4) Location Area

[0063] In order to facilitate the network device to confirm the location of the terminal device, the coverage area of each PLMN is divided into multiple location areas (LAs), and one location area can contain one or more cells. The network device stores the location area where each terminal device is currently located, and uses it as the location information for paging the terminal device in the future. Moreover, the network device pages the terminal device by paging all cells in the location area where the terminal device is located. Since there is usually an overlap between cells, the same location can be covered by multiple location areas.

[0064] The technical solutions of the embodiments of the present application will be described in detail below in conjunction with the drawings of the specification.

[0065] FIG. 1 is a structural schematic diagram of a communication system provided by an embodiment of the present application. The system includes a terminal device and a network device. Taking a 5G communication system as an example, the network device includes an access network device, a core network device and a data network (DN). The specific contents are as follows.

[0066] The terminal device can be connected to the access network device deployed by the operator through a wireless air interface, and then connected to the data network through the core network device. After the terminal device is powered on or disconnected from the network, first, a PLMN is selected. Then, under the selected PLMN, a suitable cell (Cell) is searched according to the network standard supported by the PLMN. Finally, the terminal device is camped and registered in the cell based on SIM card information. After successful registration, the terminal device can enjoy network services such as voice, data and multimedia.

[0067] In some embodiments, the process of terminal device selecting a PLMN is shown as follows:

[0068] A PLMN list is usually maintained in the terminal device, which includes PLMNs of different priorities and network standards supported by partial PLMNs. For example, as shown in Table 1, the PLMN list includes RPLMN, EPLMN, HPLMN, EHPLMN, UPLMN, OPLMN, VPLMN, and other PLMNs from top to bottom, wherein the other PLMNs refer to all the PLMNs that the terminal device can search at present. And in the order from top to bottom, the priorities of the PLMNs decrease in turn.

[0069] Table 1 PLMN list

[0070] In the process of PLMN selection of the terminal device, based on the PLMN list, the terminal device performs PLMN search in turn according to the order of PLMN priority from high to low. After successfully searching a PLMN, the terminal device selects the PLMN as the selected PLMN for subsequent cell search. For example, after searching the RPLMN, the terminal device performs cell search in the RPLMN subsequently.

[0071] In some embodiments, the process of terminal device searching a cell is shown as follows:

[0072] The selected PLMN usually supports multiple network standards, for example, the selected RPLMN supports 5G, 4G, 3G, and 2G network standards. Generally, the terminal device performs cell search according to the order of network standards from high to low, and preferentially camps in the cell of high standard. For example, cell search is performed in the 5G standard first, if no suitable cell is searched in the 5G standard, cell search is performed in the 4G standard. If no suitable cell is searched in the 4G standard, cell search is performed in the 3G standard. If no suitable cell is searched in the 3G standard, cell search is performed in the 2G standard.

[0073] After searching a suitable cell, the terminal device initiates network registration to the core network and data network through the access network device according to the information of the SIM card installed by the terminal device, so as to camp in the cell through the SIM card.

[0074] In this embodiment, the terminal device includes a user equipment (UE), a mobile station, a communication device capable of installing a SIM card, etc. For example, the terminal can be a mobile phone, a smart watch, a smart bracelet, a tablet computer, a notebook computer, a palm computer, a mobile internet device (MID), a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, or a wireless terminal in a smart home, etc. The embodiments of the present application do not limit the specific technology and specific device form of the terminal.

[0075] The access network device is mainly used to implement functions such as wireless physical layer functions, resource scheduling and wireless resource management, wireless access control, and mobility management. In this embodiment, the access network device can be an access network (AN) or a radio access network (RAN) device.

[0076] In the embodiments of the present application, the access network device includes but is not limited to: an evolved node B (eNB), a radio network controller (RNC), a node B (NB), a network device controller (BSC), a network device transceiver station (BTS), a home network device (for example, a home evolved Node B, or a home Node B, HNB), a baseband unit (BBU), an access point (AP) in a wireless fidelity (WIFI) system, a wireless relay node, a wireless backhaul node, a transmission and reception point (TRP), a transmission point (TP), and the like; it can also be a device used in a 5G, 6G, or the like system, such as a gNB or a transmission point (TRP or TP) in an NR system, one or a group of (including multiple antenna panels) antenna panels of a network device in a 5G system, or it can also be a network node constituting a gNB or a transmission point, such as a baseband unit (BBU), or a distributed unit (DU), or a RSU in a vehicle to everything (V2X) or intelligent driving scenario.

[0077] In some deployments, a gNB can include a centralized unit (CU) and a DU. A gNB can also include a radio unit (RU). The CU can implement part of the functionality of the gNB, and the DU can implement another part of the functionality of the gNB. For example, the CU can implement functionality of a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, and the DU can implement functionality of a radio link control (RLC) layer, a media access control (MAC) layer, and a physical (PHY) layer. Because information at the RRC layer can eventually become information at the PHY layer, or vice versa, high layer signaling, such as RRC layer signaling, can also be considered as being transmitted by the DU, or by the DU + CU, under this architecture. It can be understood that a network device can be a CU node, or a DU node, or a device including a CU node and a DU node. In addition, the CU can be divided into a network device in a radio access network (RAN), or the CU can be divided into a network device in a core network (CN), which is not limited in the present application.

[0078] The core network device includes an access and mobility function (AMF), a session management function (SMF), a policy control function (PCF), an operation, administration and maintenance (OAM), and the like. These function units can work independently, or can be combined together to achieve certain control functions. For example, the AMF, the SMF and the PCF can work together to complete the access control and mobility management functions of the terminal device, such as access authentication, security encryption, location registration, and the like, and the session management functions such as the establishment, release and change of the user plane transmission path, and the function of analyzing some network slice related data and terminal device related data. In the embodiment, the core network device can implement the functions of the above network elements, and the specific network element deployment mode in the core network device is not limited in the embodiment.

[0079] The data network can correspond to a plurality of different service domains, such as an IP multimedia subsystem (IMS), an Internet, a service domain related to a third-party application, and the like, and is mainly used to provide a plurality of data service for terminal devices, which can include devices such as servers (such as third-party application servers), routers, gateways, and the like.

[0080] It should be noted that FIG. 1 is only a schematic architecture diagram of a 5G communication system, and the network architecture of the communication system can also include other functional units or functional entities in addition to the functional units shown in FIG. 1, which are not limited by the embodiments.

[0081] Currently, in a roaming scenario, a terminal device can usually only search for a VPLMN. According to the network search rule of the terminal device, the terminal device will preferentially register a high-mode network of the VPLMN, and after successful registration, the VPLMN will be marked as an RPLMN and stored in a PLMN list. In a subsequent process, if the terminal device detects that the high-mode network of the RPLMN cannot be used temporarily, the terminal device will automatically fall back to a low-mode network of the RPLMN. It can be understood that, due to the change of the network mode from high to low, the terminal device cannot use high-speed and high-quality voice call services provided by the high-mode network, such as voice over long-term evolution (VoLTE) and voice over new radio (VoNR), which leads to poor communication quality of the terminal device and seriously affects the user experience.

[0082] In one example, the terminal device is in a roaming state, and the VPLMN 5G network is successfully registered. Then, the VPLMN 1 will be stored in the PLMN list as the RPLMN of the terminal device. In a subsequent process, if the terminal device detects that the network is disconnected after leaving a tracing area (TA) of the current network, and the terminal device still cannot search for a suitable cell in the current cell, the terminal device will preferentially select a low-mode network of the RPLMN to register in the process of reselecting the network, for example, to select the RPLMN 4G network to register. In this case, the network mode of the terminal device drops from 5G to 4G, which leads to poor communication quality of the terminal device.

[0083] To this end, an embodiment of the present application provides a network selection method for improving the communication quality of a terminal device after the terminal device is disconnected and reselects a network in a roaming scenario.

[0084] FIG. 2 is a schematic flowchart of a network selection method according to an embodiment of the present application. The method relates to a process of network selection by a terminal device after the terminal device is disconnected from a network in a roaming scenario. The SIM card installed in the terminal device supports a first VPLMN and a second VPLMN, the first VPLMN and the second VPLMN are different, and the second VPLMN is any one VPLMN supported by the SIM card except the first VPLMN. The method specifically includes the following steps S201-S203.

[0085] S201, the terminal device successfully registers a first network of a first network type of a first VPLMN.

[0086] In one example, the first network is a VPLMN 14G network. It should be noted that after the terminal device successfully registers the VPLMN 14G network, the VPLMN 1 will be stored in the PLMN list as the RPLMN by the terminal device.

[0087] In addition, the coverage of the first network usually includes multiple location areas, for example, a first location area and a second location area. Based on this, the terminal device successfully registers the first network of the first network type of the first VPLMN, specifically, the terminal device successfully registers a first cell of the first location area.

[0088] S202, the terminal device detects that the first network cannot provide services to the terminal device.

[0089] In some embodiments, during the process of registration update, if no cell meeting the registration condition can be searched in the first network, it is confirmed that the first network cannot provide services to the terminal device.

[0090] Specifically, after the terminal device is connected to the network, in order to enable the network device to know the specific location where the terminal device is currently located, the terminal device needs to perform registration update, including periodic registration update and mobile registration update. When the terminal device is in a connect management-Idle (CM-Idle) state and a timer of the terminal device expires, the terminal device performs the periodic registration update process. In addition, during the movement, the terminal device may move a long distance. When the TA where the terminal device is located does not match the TA supported by the terminal device (i.e., the TA issued by the AMF), the terminal device initiates the mobile registration update process.

[0091] Due to terminal device movement, first network service quality change, etc., the terminal device can leave the coverage area of the first network, or be at the edge of the coverage area of the first network, or the first network can be abnormal. In the above cases, the terminal device can not search for a cell meeting the registration condition when performing registration update, resulting in the terminal device being unable to connect to the first network, i.e., the terminal device being disconnected from the network. Therefore, if the terminal device cannot search for a cell meeting the registration condition in the first network during registration update, it is determined that the first network cannot provide services to the terminal device.

[0092] In some other embodiments, the terminal device can search for a cell meeting the registration condition in the first network during registration update, but find that these cells are all unavailable due to network congestion, being prohibited from access, link establishment failure, etc., resulting in the terminal device failing to perform registration update. In this case, the terminal device also considers that the first network cannot provide services to the terminal device.

[0093] In some other embodiments, after receiving the first indication information sent by the network device, the terminal device determines that the first network cannot provide services to the terminal device. The first indication information is used to indicate that the terminal device cannot use the first network temporarily.

[0094] Specifically, due to the terminal device being in a roaming place, the terminal device can be temporarily prohibited from using the first network by the network device in the roaming place during registration update, affected by user carrying capacity, current user quantity, use policy, etc., of the first network in the roaming place. For example, when the user quantity of the first network is greater than a threshold, in order to guarantee the communication quality of home users, the network device in the roaming place can temporarily prohibit the roaming terminal device from using the first network, and send the first indication information to the terminal device to indicate that the terminal device cannot use the first network temporarily. Therefore, after receiving the first indication information sent by the network device, the terminal device determines that the first network cannot provide services to the terminal device.

[0095] S203, if the terminal device searches for a second network of a second network standard of a second VPLMN, the terminal device registers the second network.

[0096] In this embodiment, the first network standard is the same as the second network standard, or the second network standard is higher than the first network standard. For example, the first network is a VPLMN 14G network, and the second network is a VPLMN 24G network, or the second network is a VPLMN 25G network, or the second network is a VPLMN 34G network.

[0097] In some embodiments, the terminal device supports a self-learning network selection function, for example as shown in Table 2, the terminal device supports recording the VPLMN in which it successfully registers in different roaming areas and the frequency point information of each VPLMN.

[0098] Table 2

[0099] In other embodiments, the server of the terminal device supports the self-learning network selection function. That is, each terminal device connected to the server sends the corresponding roaming area information, historical VPLMN and historical frequency point information to the server after successful registration in a roaming area. The server processes the information sent by each terminal device, generates the corresponding relationship between the roaming area, historical VPLMN and historical frequency point information for example as shown in Table 2, and stores it in the server.

[0100] Based on this, in the process of searching for a second network, the terminal device can first obtain the historical VPLMN corresponding to the current roaming area and the historical frequency point information of each VPLMN from the local or the server. Subsequently, the terminal device searches for a second network according to the historical VPLMN other than the first VPLMN, and performs cell search according to the historical frequency point information after searching for the historical VPLMN, so as to improve the possibility of successful network search. For example, in the process of roaming in Thailand, if the terminal device is disconnected from the RPLMN 52003, it will preferentially search for the network 52004 in which it has successfully registered before, and preferentially perform cell search according to the historical frequency point information f3.

[0101] It should be noted that if the terminal device does not search for the historical VPLMN corresponding to the current roaming area, it attempts to perform cell search in each VPLMN that can be searched at present and perform registration. Alternatively, if the terminal device searches for a historical VPLMN (such as 52004), but does not search for a cell that meets the second network standard and the registration condition according to the historical frequency point information (such as f3) of the VPLMN, it performs cell search in the frequency range of the second network standard of the 52004 network.

[0102] It should be understood that the terminal device can search for a second network or can not search for a second network. If it does not search for a second network, it falls back to a network of a lower standard of the RPLMN, for example, from the RPLMN 4G network to the RPLMN 3G network. If it searches for a second network, it registers the second network.

[0103] For the steps S201-S203, taking the HPLMN of the terminal device as 46000, the EHPLMNs as 46002, 46004 and 46007, and the VPLMNs corresponding to the operators signed by the SIMs as 52003, 52004 and 52005 as examples. The terminal device successfully registers the VPLMN 520034G network and marks the network as the RPLMN 520034G network. In the subsequent process, if the terminal device detects that the RPLMN 520034G cannot provide services, the terminal device can re-register the network according to other VPLMNs.

[0104] In some embodiments, referring to FIG. 3, the terminal device searches for the VPLMN 520054G network. Then, the terminal device registers the network. If the registration is successful, the terminal device switches from the RPLMN 520034G network to the VPLMN 520054G. It can be seen that the PLMN used by the terminal device changes, but the network standard remains unchanged, which can ensure the quality of the terminal device.

[0105] In some other embodiments, the terminal device searches for the VPLMN 520055G network. Then, the terminal device registers the network. If the registration is successful, the terminal device switches from the RPLMN 520034G network to the VPLMN 520055G. It can be seen that the PLMN used by the terminal device changes, and the network standard is improved, which helps to improve the communication quality of the terminal device.

[0106] Optionally, before searching for the second network of the second network standard of the second VPLMN, the terminal device can also search whether there is a second cell satisfying the registration condition in other location areas (for example, a second location area) covered by the first network.

[0107] If there is no second cell satisfying the registration condition in the other location areas of the first network, the terminal device searches for the second network.

[0108] If there is a second cell satisfying the registration condition in the other location areas of the first network, the terminal device registers the network in the second cell. If the registration in the second cell is successful, the terminal device continues to camp on the first network, avoiding the PLMN switching of the terminal device. If the registration in the second cell fails, the terminal device searches for the second network.

[0109] In addition, in the process of registering the second network, the terminal device can successfully register and camp on the network. However, the terminal device can fail to register the second network due to the following reasons: illegal user, illegal terminal, PLMN not allowed, 5G service not allowed, TA not allowed, roaming not allowed in the TA, no suitable cell under the current TA, network congestion, network service not authorized, network not accepting mobility and periodic registration, network unable to export the terminal device identity, and the like.

[0110] If the terminal device fails to register the second network, the terminal device can search for a network of a third network type of the RPLMN, i.e., a third network, where the third network type is lower than the first network type. For example, the terminal device searches for and registers with a 3G network of the RPLMN after searching for the 3G network. After successfully registering with the third network, the terminal device can camp on the third network.

[0111] If the terminal device fails to register the third network, the terminal device can continue to search for a network of the third network type of another VPLMN, i.e., a fourth network, and register with the fourth network after searching for the fourth network. For example, the terminal device searches for and registers with a 3G network of a second VPLMN after searching for the 3G network. After successfully registering with the third network, the terminal device can camp on the third network.

[0112] In summary, by using the network selection method provided in the embodiments of the present application, after the terminal device is disconnected from the network in the roaming scenario, the terminal device can preferentially connect to a high-type network of another VPLMN, and avoid the network of the terminal device from dropping from a high type to a low type as much as possible, thereby ensuring the communication quality of the terminal device and improving the user experience.

[0113] The network selection method provided in the embodiments of the present application will be further described below in combination with specific examples.

[0114] FIG. 4 is a schematic flowchart of a network selection method provided in another embodiment of the present application. The method specifically includes the following steps.

[0115] S401, the terminal device successfully registers a 4G network of a VPLMN in a first cell of a first location area, and identifies the network as a 4G network of an RPLMN. For example, after being powered on or recovering network coverage in Thailand, the terminal device successfully registers a 52003 4G network in a cell 1 of a location area 1, and identifies the currently used 52003 as an RPLMN.

[0116] S402, the terminal device detects that the RPLMN 4G network cannot temporarily provide services to the terminal device when registering with the network for an update.

[0117] In some embodiments, after detecting that the RPLMN 4G network cannot provide services to the terminal device, the terminal device can attempt network registration through the procedures shown in the following (1) to (6) to restore device network.

[0118] (1) The terminal device attempts to register a second cell of a second location area of the RPLMN 4G network.

[0119] S403a, the terminal device determines whether there is a second cell located in the second location area that can be registered in the RPLMN 4G network. If so, jump to S403b. If not, jump to S404a.

[0120] S403b, the terminal device registers in the second cell of the second location area of the RPLMN 4G network.

[0121] S403c, the terminal device determines whether the registration in the second cell of the second location area of the RPLMN 4G network is successful. If so, camp on the second cell and the network registration procedure ends. If not, jump to S403a to continue network search.

[0122] (2) The terminal device attempts to register other VPLMN 4G / 5G networks.

[0123] S404a, the terminal device determines whether other VPLMN 4G / 5G networks are searched. If so, jump to S404b; if not, jump to S405a.

[0124] In this embodiment, other VPLMN refers to VPLMNs supported by the SIM card of the terminal device, excluding the VPLMN used by the terminal device before it went offline. Taking the VPLMNs supported by the SIM card of the terminal device as an example, including 52003, 52004 and 52005, if the VPLMN used by the terminal device before it went offline is 52003, then the other VPLMNs include 52004 and 52005.

[0125] S404b, the terminal device registers in other VPLMN 4G / 5G networks.

[0126] S404c, the terminal device determines whether the registration in other VPLMN 4G / 5G networks is successful. If so, the registration procedure ends. If not, jump to S404a to continue network search.

[0127] (3) The terminal device attempts to register the RPLMN 3G network.

[0128] S405a, the terminal device judges whether the RPLMN 3G network is scanned. If the RPLMN 3G network is scanned, it jumps to S405b. If the RPLMN 3G network is not scanned, it jumps to S406a.

[0129] S405b, the terminal device registers the RPLMN 3G network.

[0130] S405c, the terminal device judges whether the RPLMN 3G network is successfully registered. If it is successfully registered, the registration process ends. If it fails to register, it jumps to S405a to continue the network search.

[0131] (4) The terminal device attempts to register other VPLMN 3G network.

[0132] S406a, the terminal device judges whether the other VPLMN 3G network is scanned. If the other VPLMN 3G network is scanned, it jumps to S406b. If the other VPLMN 3G network is not scanned, it jumps to S407a.

[0133] S406b, the terminal device registers the other VPLMN 3G network.

[0134] S406c, the terminal device judges whether the other VPLMN 3G network is successfully registered. If it is successfully registered, the registration process ends. If it fails to register, it jumps to S406a to continue the network search.

[0135] (5) The terminal device attempts to register the RPLMN 2G network.

[0136] S407a, the terminal device judges whether the RPLMN 2G network is scanned. If the RPLMN 2G network is scanned, it jumps to S407b. If the RPLMN 2G network is not scanned, it jumps to S408a.

[0137] S407b, the terminal device registers the RPLMN 2G network.

[0138] S407c, the terminal device judges whether the RPLMN 2G network is successfully registered. If it is successfully registered, the registration process ends. If it fails to register, it jumps to S407a to continue the network search.

[0139] (6) The terminal device attempts to register the other VPLMN 2G network.

[0140] S408a, the terminal device judges whether the other VPLMN 2G network is scanned. If the other VPLMN 2G network is scanned, it jumps to S406b. If the other VPLMN 3G network is not scanned, the registration process ends.

[0141] S408b, the terminal device registers the other VPLMN 2G network.

[0142] S408c, the terminal device determines whether the registration of the other VPLMN 2G network is successful.

[0143] Since the 2G network is the lowest network standard in the currently commonly used network standards, the network registration process ends regardless of whether the terminal device successfully registers the other VPLMN 2G network.

[0144] In addition, since the communication quality of 4G and 5G is good at present, and the PLMN search and switching will waste a long time. Therefore, after the terminal device is disconnected from the RPLMN 5G network, the terminal device can preferentially select and register the RPLMN 4G network, and if the RPLMN 4G network cannot be searched, the other VPLMN 5G / 4G network is searched, so as to ensure that the terminal device stays on the RPLMN as much as possible, avoid the terminal device to perform PLMN switching, and improve the network recovery rate of the terminal device.

[0145] Based on the same concept, as an implementation of the above method, an embodiment of the present application provides a network selection device. The device embodiment corresponds to the foregoing method embodiment, and for the sake of reading, the details of the foregoing method embodiment will not be described one by one, but it should be clear that the device in the present embodiment can correspondingly implement all the contents in the foregoing method embodiment.

[0146] FIG. 5 is a structural schematic diagram of a network selection device 500 provided by an embodiment of the present application. The network selection device 500 is applied to a terminal device, a SIM card of the terminal device supports a first VPLMN and a second VPLMN, the device 500 includes a network registration module 501 and a network detection module 502.

[0147] The network registration module 501 is configured to register a first network of a first network standard of the first VPLMN. For example, when a coverage area of the first network includes a first location area and a second location area which are different and partially overlapped, a first cell of the first location area is registered.

[0148] The network detection module 502 is configured to, after the registration of the first network is successful, detect whether the first network can provide services to the terminal device.

[0149] The network registration module 501 is further configured to, after the first network cannot provide services to the terminal device and a second network of a second network standard of the second VPLMN is searched, register the second network. The first network standard is the same as the second network standard, or the second network standard is higher than the first network standard.

[0150] Optionally, the network registration module 501 is further configured to register a second network of a second network type of the second VPLMN if no second cell meeting the registration condition is searched in the second location area of the first network; or register the second network if the second cell meeting the registration condition is searched in the second location area of the first network but the registration of the second cell fails.

[0151] Optionally, the network registration module 501 is further configured to mark the first VPLMN as a registered public land mobile network (RPLMN); and register a third network of a third network type of the RPLMN after the registration of the second network fails, the third network type being lower than the first network type.

[0152] Optionally, the network registration module 501 is further configured to register a fourth network of the third network type of the second VPLMN after the registration of the third network fails.

[0153] Optionally, the network registration module 501 is further configured to acquire frequency point information of the second network in the process of registering the second network; search a target cell meeting the registration condition in the second network according to the frequency point information; and register the target cell.

[0154] The embodiment of the present application further provides a terminal device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the network selection method shown in each of the above embodiments when executing the computer program.

[0155] The embodiment of the present application further provides a chip, as shown in FIG. 6, which comprises a processor and a memory, and the memory stores a computer program, and the computer program is executed by the processor to implement the network selection method in each of the above embodiments.

[0156] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the network selection method provided in each of the above embodiments.

[0157] The embodiment of the present application further provides a computer program product, which comprises a computer program, and when the computer program is run by an electronic device, the electronic device implements the network selection method provided in each of the above embodiments.

[0158] It should be understood that the size of the serial number of each step in the above embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0159] It should be appreciated that the processor referred to in the embodiments of the present application can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic components, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0160] It should also be understood that the memory referred to in the embodiments of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically EPROM (EEPROM) or a flash memory. The volatile memory can be a random access memory (RAM) used as an external cache. By way of example but not limitation, many forms of RAM can be used, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM) and direct rambus RAM (DRRAM).

[0161] In the embodiments provided in the present application, the division of each framework or module is only a logical functional division, and when actually implemented, there can be another division manner, for example, a plurality of frameworks or modules can be combined or integrated into another system, or some features can be ignored or not executed.

[0162] In addition, each functional module in each embodiment of the present application can be integrated in one processing module, or each module can be physically present alone, or two or more modules can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software functional module.

[0163] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0164] In the present application, the reference to "one embodiment" or "some embodiments" and the like means that the specific features, structures or characteristics described in connection with the embodiment are included in one or more embodiments of the present application. Therefore, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in further some embodiments" and the like appearing in different places in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "include", "contain", "have" and their variants mean "include but not limited to", unless otherwise specifically emphasized.

[0165] The above-described embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A network selection method, characterized in that: Applied to a terminal device, the terminal is equipped with a subscriber identity module (SIM) card, the SIM card supports a first VPLMN and a second VPLMN, and the method includes: Successfully registering with the first network of the first network standard of the first VPLMN; detecting that the first network cannot provide services to the terminal device, searching for a second network of a second network standard of the second VPLMN; wherein the first network standard is the same as the second network standard, or the second network standard is higher than the first network standard; After searching for the second network, register with the second network.

2. The method according to claim 1, characterized in that The detecting that the first network is unable to provide services to the terminal device includes: In the first network, no cell meeting the registration conditions can be found; or, A first indication information is received, where the first indication information is used to indicate that the terminal device cannot temporarily use the first network.

3. The method according to claim 1 or 2, characterized in that The coverage area of ​​the first network includes a first location area and a second location area that are different and partially overlap. Accordingly, the first network of the first network standard in which the first VPLMN is successfully registered includes: The first cell of the first location area is successfully registered.

4. The method according to claim 3, characterized in that After searching for a second network of the second network standard of the second VPLMN, registering the second network includes: If no second cell meeting the registration condition is found in the second location area, searching for a second network of the second network standard of the second VPLMN; and after finding the second network, registering with the second network; or If a second cell meeting the registration condition is searched in the second location area and registration of the second cell fails, searching for a second network of the second network standard of the second VPLMN; and registering the second network after searching for the second network.

5. The method according to any one of claims 1 to 4, characterized in that After successfully registering the first network of the first network standard of the first VPLMN, the method further includes: marking the first VPLMN as a registered public land mobile network RPLMN; and After failing to register the second network, register a third network of a third network standard of the RPLMN; wherein the third network standard is lower than the first network standard.

6. The method according to claim 5, characterized in that The method further comprises: After registering the third network fails, registering a fourth network of the third network standard of the second VPLMN.

7. The method according to any one of claims 1 to 6, characterized in that The registering the second network of the second network standard of the second VPLMN includes: Obtaining frequency information of the second network; searching, according to the frequency information, for a target cell in the second network that meets a registration condition; Register the target cell.

8. The method according to claim 7, characterized in that The frequency information is the historical frequency information of the second network stored locally; The frequency information is historical frequency information of the second network obtained from a server, and the historical frequency information is uploaded by the terminal device and / or other terminal devices.

9. A terminal device, characterized in that: The method comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method according to any one of claims 1 to 8 when executing the computer program.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

11. A chip, characterized in that: The chip includes a processor and a memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method according to any one of claims 1 to 8 is implemented.

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