Communication method and communication device

Abstract

The invention discloses a communication method and a communication device, and relates to the technical field of wireless communication. The terminal monitors a signal strength of a serving cell of the terminal during the presence of an emergency bearer of the terminal. And when the signal strength of the serving cell is smaller than or equal to a first threshold value, the terminal performs neighbor cell signal measurement to obtain at least one candidate neighbor cell, and the signal strength of the candidate neighbor cell is larger than the first threshold value. And when the neighbor cell meeting the emergency bearer condition does not exist in the at least one candidate neighbor cell, the terminal continues to reside in the current service cell, so that the situation that the emergency bearer is released after cell change is avoided, the emergency bearer of the terminal can continue to exist, and when a network side pages the terminal or other terminals to carry out emergency call callback, the user experience is improved. According to the invention, the terminal can be paged, and the correct position of the terminal can be obtained when the network side carries out emergency positioning on the terminal.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a communication method and communication device. Background Technology

[0002] In the field of communications, terminals can initiate emergency services in scenarios where services are restricted, such as when there is no home network, the account is in arrears, or a subscriber identity module (SIM) card is not installed. For example, the terminal can first initiate emergency registration with the network side, and after successful emergency registration, an emergency bearer will be established.

[0003] After an emergency bearer is established, the terminal can make emergency calls. During the existence of the emergency bearer, the terminal also supports functions such as emergency call callback and emergency location tracking. However, if the terminal changes its serving cell during the existence of the emergency bearer, the current emergency bearer may be released.

[0004] For example, a terminal is currently registered in cell 1, which is the terminal's serving cell. Cell 1 supports emergency bearers. The terminal initiates emergency registration with cell 1 to establish an emergency bearer. After the emergency bearer is established, the terminal makes an emergency call. After the emergency call ends, the emergency bearer remains active for a period of time. If the terminal moves and changes its serving cell to cell 2 through cell reselection, the emergency bearer may be released because cell 2 cannot provide emergency services to the terminal. The release of the emergency bearer will cause the terminal's emergency services to be interrupted. When the network tries to page the terminal or other terminals make an emergency call callback, it will be unable to page the terminal. Furthermore, when the network performs emergency location tracking on the terminal, it will be unable to obtain the correct terminal location. Summary of the Invention

[0005] This application provides a communication method and a communication device that can reduce the risk of emergency bearers being released due to changes in the serving cell of a terminal.

[0006] In a first aspect, this application provides a communication method executed by a terminal, or by a chip, chip system, or circuit within the terminal. The communication method may include: during an emergency bearer period, the terminal monitors the signal strength of its serving cell. When the signal strength of the serving cell is less than or equal to a first threshold, the terminal performs neighbor cell signal measurement to obtain at least one candidate neighbor cell, wherein the signal strength of the candidate neighbor cell is greater than the first threshold. When no neighbor cell among the at least one candidate neighbor cell meets the emergency bearer condition, the terminal continues to camp on the current serving cell.

[0007] The emergency bearer existence period refers to the time from the establishment of the emergency bearer between the terminal and the PLMN to which the terminal's serving cell belongs to the period from the release of the emergency bearer. After the terminal establishes an emergency bearer with the PLMN to which its serving cell belongs, if an emergency call is made, the terminal's emergency bearer will still exist for the aforementioned period after the emergency call ends.

[0008] The communication method provided in this application allows the terminal to continue camping on the current serving cell when no candidate neighbor cell meets the emergency bearer conditions during the cell change process. This avoids the emergency bearer being released after the cell change, ensuring the terminal's emergency bearer continues to exist. This is beneficial for the network side to be able to page the terminal when paging the terminal or other terminals make an emergency call back, and for the network side to obtain the correct location of the terminal when performing emergency positioning.

[0009] In one optional implementation, the aforementioned emergency bearer conditions may include: the Public Land Mobile Network (PLMN) to which the candidate neighbor cell belongs is included in the specified PLMN list within the terminal, and the candidate neighbor cell supports emergency bearer. The specified PLMN list within the terminal is a list of Public Land Mobile Network (RPLMN) that the terminal has successfully registered with, or an equivalent Public Land Mobile Network (EPLMN) list. The EPLMN list is the list sent by the network device after the terminal performs emergency registration.

[0010] If a candidate neighbor cell supports emergency bearer, and the PLMN to which the candidate neighbor cell belongs is included in the RPLMN list or EPLMN list, then the terminal can guarantee the continuity of emergency bearer when moving between the serving cell and the candidate neighbor cell.

[0011] In one alternative implementation, if there is no neighboring cell among at least one candidate neighboring cell that meets the emergency bearer condition, the terminal may continue to camp on the serving cell when the signal strength of the serving cell is greater than or equal to a second threshold, wherein the second threshold is less than the first threshold.

[0012] In the above implementation, when the signal strength of the serving cell is greater than or equal to the second threshold, the terminal can continue to camp on the serving cell. This not only ensures that the terminal's emergency bearer continues to exist, but also allows the terminal to continue communicating with the network through the serving cell.

[0013] In one alternative implementation, after determining at least one candidate neighbor cell, if there is a first neighbor cell among the at least one candidate neighbor cell that meets the emergency bearer conditions, the terminal can switch from the current serving cell to the first neighbor cell.

[0014] In the above implementation, if there is a first neighboring cell among the candidate neighboring cells that meets the emergency bearer conditions, the terminal can change from the current serving cell to the first neighboring cell. This not only allows the terminal to continue communicating with the network through the first neighboring cell and continue to use network services, but also allows the terminal's emergency bearer to continue to exist, so as to avoid the emergency bearer being released after the cell change.

[0015] In one alternative implementation, when at least one candidate neighbor cell includes not only a first neighbor cell that meets the emergency bearer conditions but also a second neighbor cell that does not meet the emergency bearer conditions, the terminal will still choose to switch from the current serving cell to the first neighbor cell, even if the signal strength of the second neighbor cell is greater than that of the first neighbor cell, so as to ensure that the terminal's emergency bearer can continue to exist.

[0016] Secondly, this application provides a communication device that can be applied to a terminal. The communication device may include:

[0017] The signal measurement module is used to monitor the signal strength of the serving cell of the terminal during the emergency bearer existence period of the terminal; when the signal strength of the serving cell is less than or equal to a first threshold, neighbor cell signal measurement is performed to obtain at least one candidate neighbor cell; the signal strength of the candidate neighbor cell is greater than the first threshold.

[0018] The control module is used to continue camping in the serving cell when there is no neighboring cell among at least one candidate neighboring cell that meets the emergency carrying conditions.

[0019] In one optional implementation, the emergency bearer condition may include: the Public Land Mobile Network (PLMN) to which the candidate neighbor cell belongs is included in the specified PLMN list within the terminal, and the candidate neighbor cell supports emergency bearer. The specified PLMN list within the terminal is a list of Public Land Mobile Network (RPLMN) that the terminal has successfully registered with, or an equivalent Public Land Mobile Network (EPLMN) list; the EPLMN list is the list sent by the network device after the terminal performs emergency registration.

[0020] In one alternative implementation, the control module can be specifically used to: continue camping in the serving cell when the signal strength of the serving cell is greater than or equal to a second threshold; wherein the second threshold is less than the first threshold.

[0021] In one alternative implementation, the control module can also be used to: switch from the serving cell to the first neighboring cell when there is a first neighboring cell among at least one candidate neighboring cell that meets the emergency carrying conditions.

[0022] In one alternative implementation, the at least one candidate neighbor cell mentioned above also includes a second neighbor cell that does not meet the emergency bearer condition; the signal strength of the second neighbor cell is greater than the signal strength of the first neighbor cell.

[0023] Thirdly, this application also provides a communication device, which is a terminal or a chip in a terminal. The communication device may include a processor and a memory; the memory stores a computer program; the processor is used to read the computer program stored in the memory and execute any of the communication methods provided in the first aspect.

[0024] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which are used to cause a computer to perform any of the communication methods provided in the first aspect above.

[0025] Fifthly, this application provides a computer program product comprising computer-executable instructions, the computer-executable instructions being used to cause a computer to perform any of the communication methods provided in the first aspect above.

[0026] The technical effects that can be achieved by any of the second to fifth aspects mentioned above can be referred to the description of the beneficial effects in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0027] Figure 1 A schematic diagram of a communication system provided in an embodiment of this application;

[0028] Figure 2 This is a schematic diagram illustrating a scenario where a cell is changed during terminal movement.

[0029] Figure 3 This is a schematic diagram illustrating a scenario where a cell change occurs during the movement of another type of terminal.

[0030] Figure 4 A flowchart illustrating a communication method provided in an embodiment of this application;

[0031] Figure 5 A flowchart illustrating another communication method provided in an embodiment of this application;

[0032] Figure 6 This application provides an embodiment of the interaction flowchart between a terminal and a base station during a communication process;

[0033] Figure 7 This application provides another flowchart illustrating the interaction between a terminal and a base station during a communication process.

[0034] Figure 8 This application provides another flowchart illustrating the interaction between a terminal and a base station during a communication process.

[0035] Figure 9 This is a schematic diagram illustrating cell change during terminal movement, provided as an embodiment of this application.

[0036] Figure 10 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0037] Figure 11 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings. The terminology used in the implementation section of this application is only for explaining specific embodiments of this application and is not intended to limit this application.

[0039] Before introducing the specific solutions provided in the embodiments of this application, some terms used in this application will be explained to facilitate understanding by those skilled in the art, but the terms used in this application are not limited.

[0040] (1) Emergency Bearer: For terminals supporting IP Multimedia Subsystem (IMS), emergency services can be initiated in scenarios with service restrictions such as no home network, account arrears, or no SIM card installed. Here, IP refers to the Internet Protocol. Before initiating an emergency service, the terminal can first initiate emergency registration with the network side. Emergency registration refers to the terminal's registration with the current Public Land Mobile Network (PLMN) solely for the purpose of performing emergency services. After successful emergency registration, an emergency bearer is established between the terminal and the network side. In the 4th generation (4G) communication environment, the emergency bearer can be called an emergency bearer. In the 5th generation (5G) communication environment, the emergency bearer can be an emergency protocol data unit session (emergency PDU session), or an emergency PDU session. The network supports context mapping between 5G emergency PDU sessions and 4G emergency bearers. In this application embodiment, the 4G emergency bearer and the 5G emergency PDU session are collectively referred to as emergency bearers.

[0041] (2) Mobility management manages terminal location information, security, and service continuity, aiming to optimize the connection between the terminal and the communication network, thereby ensuring the application of various network services. Mobility management changes the terminal's serving cell so that the terminal can enjoy uninterrupted service regardless of its movement within the network coverage area.

[0042] In this application embodiment, "multiple" refers to two or more. Therefore, in this application embodiment, "multiple" can also be understood as "at least two". "At least one" can be understood as one or more, such as one, two, or more. For example, "including at least one" means including one, two, or more, and it does not limit which ones are included. For example, including at least one of A, B, and C, then it could include A, B, C, A and B, A and C, B and C, or A and B and C. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.

[0043] Unless otherwise stated, the ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects, and are not used to limit the order, sequence, priority or importance of multiple objects.

[0044] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0045] The technical solutions in this application embodiment can be applied to various communication systems, such as Universal Mobile Telecommunications System (UMTS), Wireless Local Area Network (WLAN), Wireless Fidelity (Wi-Fi) system, 4th generation (4G) mobile communication system, such as Long Term Evolution (LTE) system, 5th generation (5G) mobile communication system, such as New Radio (NR) system, and future evolution communication systems, etc.

[0046] This application will present various aspects, embodiments, or features relating to systems that may include multiple devices, components, modules, etc. It should be understood and appreciated that individual systems may include additional devices, components, modules, etc., and / or may not include all devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these approaches may also be used. Additionally, in the embodiments of this application, words such as "exemplarily," "for example," etc., are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as an "example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the term "example" is intended to present concepts 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 consistent unless their distinction is emphasized.

[0047] To facilitate understanding of the embodiments of this application, let's first take... Figure 1 The communication system shown in the diagram is used as an example to describe in detail the communication system applicable to the embodiments of this application. For example... Figure 1 As shown, the communication system 1000 includes a radio access network (RAN) 100 and a core network (CN) 200. In some embodiments, the communication system 1000 may also include a data network (DN) 300.

[0048] The following sections respectively address... Figure 1 The RAN100, CN100, and DN300 mentioned herein will be described in detail.

[0049] (1)RAN

[0050] RAN100 may include at least one network device (also referred to as a radio access network device or access network device, such as...) Figure 1 110a and 110b, collectively referred to as 110, may also include at least one terminal device (such as...). Figure 1 In the diagram, 120a-120j (collectively referred to as 120) are used. Terminal device 120 can be connected to network device 110 wirelessly. Terminal devices and network devices can be interconnected via wired or wireless means.

[0051] Network devices and terminal devices can be fixed-location or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the network devices and terminal devices. Furthermore, the roles of network devices and terminal devices can be relative, for example, Figure 1 The helicopter or drone 120i can be configured as a mobile access network device. For terminal devices 120j that access the wireless access network 100 via 120i, 120i is a network device; however, for network device 110a, 120i is a terminal device, meaning that 110a and 120i communicate via a wireless air interface protocol. Alternatively, 110a and 120i can also communicate via a network device-to-network device interface protocol; in this case, 120i is also a network device relative to 110a. Therefore, both network device 110 and terminal device 120 can be collectively referred to as communication devices. Figure 1 110a and 110b can be referred to as communication devices with network equipment functions. Figure 1 The 120a-120j in the text can be referred to as communication devices with terminal equipment functions.

[0052] (1.1) Terminal equipment

[0053] Terminal equipment can also be called user equipment (UE), terminal, user device, access terminal, user unit, user station, mobile station, mobile station (MS), remote station, remote terminal, mobile device, user terminal, terminal unit, terminal station, terminal device, wireless communication equipment, user agent, or user device.

[0054] For example, the terminal device in this application embodiment may be a mobile phone, a personal digital assistant (PDA) computer, a laptop computer, a tablet computer, a drone, a computer with wireless transceiver capabilities, a machine-type communication (MTC) terminal device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, an internet of things (IoT) terminal device, a wireless terminal device in industrial control, a wireless terminal device in self-driving, a wireless terminal device in remote medical care, a wireless terminal device in a smart grid, a wireless terminal device in transportation safety, a wireless terminal device in a smart city, a wireless terminal device in a smart home (such as a game console, smart TV, smart speaker, smart refrigerator, and fitness equipment), or an in-vehicle terminal device.

[0055] (1.2) Network equipment

[0056] Network devices can be base stations, evolved NodeBs (eNodeBs), access points (APs), transmission reception points (TRPs), next-generation NodeBs (gNBs), base stations in future mobile communication systems, or access nodes in WiFi systems. Network devices can be macro base stations, micro base stations, indoor stations, relay nodes, donor nodes, or radio controllers in open RAN (O-RAN) or cloud radio access network (CRAN) scenarios. Optionally, network devices can also be servers, wearable devices, vehicles, or in-vehicle equipment. For example, network devices in vehicle-to-everything (V2X) technology can be roadside units (RSUs). All or part of the functions of the network devices 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 network devices in this application can also be logical nodes, logical modules, or software capable of implementing all or part of the network device functions.

[0057] In another possible scenario, multiple network devices collaborate to assist terminal devices in achieving wireless access, with each network device performing a portion of the base station's functions. For example, network devices can be central units (CUs), distributed units (DUs), CU-control plane (CPs), CU-user plane (UPs), or radio units (RUs), etc. CUs and DUs can be configured separately or included in the same network element, such as a baseband unit (BBU). RUs can be included in radio equipment or radio units, such as remote radio units (RRUs), active antenna units (AAUs), or remote radio heads (RRHs).

[0058] 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.

[0059] In this embodiment, the functions of the network device can be executed by modules (such as chips) within the network device, or by a control subsystem that includes network device functions. This control subsystem, including network device functions, can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal device can be executed by modules (such as chips or modems) within the terminal device, or by a device that includes terminal functions.

[0060] (2)CN

[0061] The CN200 can include multiple core network elements, and radio access network devices can connect to these core network elements wirelessly or via wired connections. Core network elements and radio access network devices can be independent physical devices, or the functions of core network elements and the logical functions of radio access network devices can be integrated onto the same physical device. Alternatively, a single physical device can integrate some of the functions of core network elements and some of the functions of radio access network devices.

[0062] Taking a 5G mobile communication system as an example, in a 5G NR system, CN200 can be referred to as the 5G core network (5GC). The core network elements in the 5G core network can include access and mobility management function (AMF) elements, user plane function (UPF) elements, and emergency call session control function (CSCF) elements. Emergency CSCF elements are used to handle emergency services and emergency sessions; for example, an emergency CSCF element can route emergency service requests to the correct emergency center or public safety answering point (PSAP). The 5G core network can also include other core network elements, such as session management function (SMF) elements, policy control function (PCF) elements, and application function (AF) elements. The aforementioned RAN100 can be referred to as a 5G radio access network. Network equipment in the 5G radio access network, connected to the core network elements, can include 5G base stations (gNBs) and 4G base stations (ng-eNBs) connected to the 5G core network. The serving base station (gNB) of the terminal equipment is responsible for providing the 5G NR user plane and control plane protocol functions for the terminal equipment. The serving base station (ng-eNB) of the terminal equipment is responsible for providing the 4G evolved universal terrestrial radio access (E-UTRA) user plane and control plane protocol functions for the terminal equipment.

[0063] Taking a 4G mobile communication system as an example, in a 4G LTE system, CN200 can be referred to as the 4G core network or the evolved packet core (EPC). Core network elements in the 4G core network can include Emergency CSCF elements, Mobility Management Entity (MME) elements, and Serving Gateway (S-GW) elements. The aforementioned RAN100 can be referred to as the 4G radio access network or the evolved universal terrestrial radio access network (E-UTRAN). Network equipment in the 4G radio access network connected to the core network elements can include 4G base stations (eNBs) and 5G base stations (en-gNBs) connected to the 4G core network. The serving base station (eNB) of the terminal equipment is responsible for providing the 4G LTE user plane and control plane protocol functions for the terminal equipment. The serving base station (en-gNB) of the terminal equipment is responsible for providing the 5G NR user plane and control plane protocol functions for the terminal equipment.

[0064] (3)DN

[0065] DN300, also known as a packet data network (PDN), is a network located outside the carrier's network. DN300 can deploy application servers corresponding to various services, providing a wide range of possible services to terminal devices.

[0066] It should be noted that the network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems, that is, the methods provided in the embodiments of this application can be applied to various communication systems.

[0067] It is understood that the solutions in the embodiments of this application can be applied to a variety of possible communication systems, such as 5G communication systems or future communication systems. The aforementioned network elements or functions can be network components in hardware devices, software functions running on dedicated hardware, or virtualized functions instantiated on a platform (e.g., a cloud platform). The embodiments of this application do not limit the specific technologies or device forms used in the network devices. For ease of description, a base station is used as an example of a network device in the following description. The terminal device is hereinafter referred to as a terminal.

[0068] In this embodiment, the functions of the base station can be executed by modules (such as chips) within the base station, or by a control subsystem that includes base station functions. This control subsystem can be a control center in the aforementioned application scenarios such as smart grids, industrial control, intelligent transportation, and smart cities. Similarly, the functions of the terminal can be executed by modules (such as chips or modems) within the terminal, or by a device that includes terminal functions.

[0069] In this embodiment, the base station sends downlink signals or downlink information to the terminal, with the downlink information carried on the downlink channel; the terminal sends uplink signals or uplink information to the base station, with the uplink information carried on the uplink channel.

[0070] For terminals supporting IMS, emergency services can be initiated in scenarios with service restrictions such as no home network, account arrears, or no SIM card installed. Before initiating an emergency service, the terminal can first initiate emergency registration with the network side. After successful emergency registration, an emergency bearer is established between the terminal and the network side. After the emergency bearer is established, the terminal can make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time. During the existence of the emergency bearer, the terminal also supports functions such as emergency call callback and emergency location. If the terminal moves and changes its serving cell through cell reselection, the emergency bearer may be released because the new serving cell cannot provide emergency service to the terminal, resulting in the interruption of the terminal's emergency service.

[0071] For example, in one scenario, such as Figure 2As shown, assuming the terminal's current serving cell is RAN1, corresponding to base station A, the coverage area of ​​RAN1 can be understood as the coverage area of ​​the signal transmitted by base station A. When the terminal is within the coverage area of ​​RAN1, it can receive downlink signals sent by base station A. Assuming the PLMN to which RAN1 belongs is PLMN1, when RAN1 can only provide emergency service to the terminal, the terminal can initiate emergency registration with PLMN1 through base station A. Upon successful emergency registration, PLMN1 sends a registration success notification to the terminal, which carries a list of equivalent public land mobile networks (EPLMNs). After successful emergency registration, an emergency bearer is established between the terminal and PLMN1. PLMN1 can provide emergency service to the terminal through base station A, and the terminal can make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time. As the terminal moves, when it reaches the edge of base station A's signal coverage area, the signal strength received by the terminal from base station A significantly decreases. At this point, mobility management can be used to change the terminal's serving cell so that the terminal can enjoy uninterrupted service regardless of its movement within the network coverage area.

[0072] Assuming the terminal receives downlink signals from both base station B and base station C at its current location, with base station B having a stronger signal than base station C, the terminal can change its serving cell to cell RAN2 corresponding to base station B. However, if cell RAN2 belongs to PLMN2 instead of PLMN1, and PLMN2 is not included in the EPLMN list, changing the serving cell to RAN2 may cause the emergency bearer established between the terminal and PLMN1 to be released. This results in the interruption of the terminal's emergency services. Consequently, when the network attempts to page the terminal or other terminals make emergency callbacks, it will be unable to page the terminal. Furthermore, the network will be unable to obtain the correct terminal location during emergency positioning.

[0073] In another scenario, such as Figure 3As shown, assuming the terminal is currently serving in cell RAN1, which corresponds to base station A, the coverage area of ​​cell RAN1 can be understood as the coverage area of ​​the signal transmitted by base station A. When the terminal is within the coverage area of ​​cell RAN1, it can receive downlink signals sent by base station A. Assuming cell RAN1 belongs to PLMN1, when cell RAN1 can only provide emergency service to the terminal, the terminal can initiate emergency registration with PLMN1 through base station A. After successful emergency registration, an emergency bearer is established between the terminal and PLMN1. PLMN1 can then provide emergency service to the terminal through base station A, allowing the terminal to make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time. As the terminal moves, when it reaches the edge of base station A's signal coverage area, the signal strength received by the terminal from base station A significantly decreases. At this point, mobility management can be used to change the terminal's serving cell.

[0074] Assuming the terminal receives downlink signals from base stations D and E at its current location, and the signal strength of base station D is greater than that of base station E, the terminal can change its serving cell to cell RAN4 corresponding to base station D. If cell RAN4 does not support emergency bearers, for example, if cell RAN4 does not support IMS emergency bearers, the emergency bearer established between the terminal and PLMN1 may be released, which will also cause the terminal's emergency services to be interrupted. When the network side makes an emergency call back to the terminal or other terminals, it will not be able to page the terminal, and when the network side performs emergency location on the terminal, it will not be able to obtain the correct terminal location.

[0075] Based on this, embodiments of this application provide a communication method that can be executed by a terminal, or by a chip, chipset, or module within the terminal. This communication method may include: during the existence of the terminal's emergency bearer, when the terminal detects that the signal strength of its serving cell is less than or equal to a first threshold, it can perform neighbor cell signal measurement to determine at least one candidate neighbor cell whose signal strength is greater than the first threshold. The existence period of the terminal's emergency bearer refers to the time from the establishment of the emergency bearer between the terminal and the PLMN to which the terminal's serving cell belongs to the release of the emergency bearer. When no neighbor cell among the candidate neighbor cells meets the emergency bearer conditions, the terminal can continue to camp on its current serving cell to avoid the emergency bearer being released after a cell change, allowing the terminal's emergency bearer to continue to exist. This is beneficial for the network side to be able to page the terminal when paging the terminal or other terminals making emergency call callbacks, and for the network side to obtain the correct location of the terminal during emergency positioning.

[0076] Figure 4A flowchart of a communication method provided in an embodiment of this application is illustrated by way of example. This communication method can be executed by a terminal, or by a chip, chipset, or module within a chip in the terminal. Figure 4 As shown, the communication method executed by the terminal may include the following steps:

[0077] S401, during the period of emergency bearer existence of the terminal, monitor the signal strength of the serving cell of the terminal.

[0078] The serving cell of the terminal refers to the cell corresponding to the base station that is providing services to the terminal.

[0079] In one embodiment, when no SIM card is installed in the terminal, the terminal enters a restricted service scenario and can initiate emergency services. In another embodiment, when the account corresponding to the SIM card in the terminal is in arrears, the terminal enters a restricted service scenario and can initiate emergency services. In yet another embodiment, when there is currently no home network, the terminal enters a restricted service scenario. For example, the operator corresponding to the SIM card in the terminal is a first network operator, but the location of the terminal is not within the service range of the first network operator, and there is no network deployed by the first network operator. However, there may be a network deployed by a second network operator. In this case, the terminal currently has no home network and enters a restricted service scenario, where the terminal can initiate emergency services.

[0080] Before initiating an emergency service, the terminal can initiate an emergency registration with the PLMN to which its serving cell belongs. After successful emergency registration, the PLMN to which the terminal's serving cell belongs is one of the PLMNs that the terminal has successfully registered. The PLMN to which the terminal's serving cell belongs is stored in the terminal's list of registered public land mobile networks (RPLMNs). Furthermore, the PLMN to which the terminal's serving cell belongs sends a registration success notification to the terminal, which carries the EPLMN list. The PLMNs included in the EPLMN list are equivalent to the PLMNs in the RPLMN list.

[0081] After successful emergency registration, an emergency bearer is established between the terminal and the network. Once established, the terminal can make emergency calls. Even after an emergency call ends, the emergency bearer remains active for a period of time. During the existence of the emergency bearer, the terminal also supports functions such as emergency call callback and emergency location tracking. While the terminal's emergency bearer is active, the terminal monitors the signal strength of its serving cell in real time. When the signal strength of the serving cell weakens, the terminal can change its serving cell.

[0082] S402, when the signal strength of the serving cell of the terminal is less than or equal to the first threshold, neighbor cell signal measurement is performed to obtain at least one candidate neighbor cell.

[0083] The first threshold can be understood as the maximum value of the signal strength range that triggers the terminal to change cells. When the signal strength of the terminal's serving cell is less than or equal to the first threshold, the terminal can change its serving cell or choose to continue camping on the current serving cell. When the signal strength of the serving cell is less than or equal to the first threshold, the terminal can perform neighbor cell signal measurement to determine one or more candidate neighbor cells, where the signal strength of each candidate neighbor cell is greater than the first threshold.

[0084] S403: When there is no neighboring cell among at least one candidate neighboring cell that meets the emergency carrying conditions, continue to reside in the current serving cell.

[0085] The emergency bearer conditions may include: the PLMN to which the candidate neighbor cell belongs is included in the specified PLMN list within the terminal, and the candidate neighbor cell supports emergency bearer. The specified PLMN list within the terminal can be an RPLMN list or an EPLMN list. If a candidate neighbor cell supports emergency bearer and the PLMN to which the candidate neighbor cell belongs is included in the RPLMN list or the EPLMN list, then the terminal's emergency bearer continuity can be guaranteed when the terminal moves between the serving cell and the candidate neighbor cell.

[0086] Taking candidate neighbor cell a as an example, if the PLMN to which candidate neighbor cell a belongs is included in the RPLMN list and candidate neighbor cell a supports emergency bearer, then candidate neighbor cell a can be considered to meet the emergency bearer condition; or, if the PLMN to which candidate neighbor cell a belongs is included in the EPLMN list and candidate neighbor cell a supports emergency bearer, for example, candidate neighbor cell a supports IMS emergency bearer, then candidate neighbor cell a can be considered to meet the emergency bearer condition.

[0087] Taking candidate neighbor cell b as an example, if the PLMN to which candidate neighbor cell b belongs is neither included in the RPLMN list nor in the EPLMN list, even though candidate neighbor cell b supports emergency bearer, candidate neighbor cell b does not meet the emergency bearer condition; or, if the PLMN to which candidate neighbor cell b belongs is included in the RPLMN list, but candidate neighbor cell b does not support emergency bearer, candidate neighbor cell b also does not meet the emergency bearer condition; or, if the PLMN to which candidate neighbor cell b belongs is included in the EPLMN list, but candidate neighbor cell b does not support emergency bearer, for example, candidate neighbor cell b does not support IMS emergency bearer, candidate neighbor cell b also does not meet the emergency bearer condition.

[0088] When none of the candidate neighbor cells meet the emergency bearer conditions, the terminal can continue to camp on the current serving cell. In some embodiments, when the signal strength of the serving cell is greater than or equal to a second threshold, the terminal can continue to camp on the current serving cell. The second threshold can be understood as the minimum value of the signal strength range that triggers the terminal to change cells, and the second threshold is less than the first threshold. When the signal strength of the terminal's serving cell is less than the second threshold, the terminal and the base station corresponding to the current serving cell cannot continue to communicate. The terminal can select a target neighbor cell from at least one candidate neighbor cell and change from the current serving cell to the target neighbor cell to maintain the communication connection and continue to communicate with the network. When the signal strength of the serving cell is greater than or equal to the second threshold, the terminal and the base station corresponding to the current serving cell can continue to communicate. In this case, if none of the candidate neighbor cells meet the emergency bearer conditions, the terminal can continue to camp on the current serving cell to avoid the emergency bearer being released after cell change, so that the terminal's emergency bearer can continue to exist. This is beneficial for the network side to be able to page the terminal when paging the terminal or other terminals making emergency call callbacks, and for the network side to obtain the correct location of the terminal when performing emergency location.

[0089] In some embodiments, after obtaining at least one candidate neighbor cell, if a first neighbor cell that meets the emergency bearer conditions exists among the at least one candidate neighbor cell, the terminal can switch from its current serving cell to the first neighbor cell. For example, the terminal can disconnect from its current serving cell and connect to the first neighbor cell, which is referred to as the terminal's new serving cell.

[0090] In some embodiments, after obtaining at least one candidate neighbor cell, if the at least one candidate neighbor cell includes a first neighbor cell that meets the emergency bearer conditions and a second neighbor cell that does not meet the emergency bearer conditions, and the signal strength of the second neighbor cell is greater than the signal strength of the first neighbor cell, the terminal can switch from the current serving cell to the first neighbor cell so that the terminal's emergency bearer can be prevented from being released and the emergency bearer can be guaranteed to be continuous.

[0091] To facilitate understanding, the communication method provided in this application will be further explained below through several specific embodiments.

[0092] In one embodiment, if no neighboring cells meeting the emergency bearer conditions exist in the surrounding environment, the terminal can continue to camp on the current serving cell. For example, as shown... Figure 5 As shown, in this embodiment, the communication method executed by the terminal may include the following steps:

[0093] S501, the terminal performs emergency registration and establishes an emergency bearer with the network side.

[0094] Assume the serving cell of the terminal is cell a, corresponding to base station A. When the terminal needs to initiate an emergency service within the coverage area of ​​cell a, it can initiate an emergency registration with the PLMN to which cell a belongs. After successful emergency registration, the PLMN to which cell a belongs is one of the PLMNs that the terminal has successfully registered with. The PLMN to which cell a belongs is stored in the terminal's RPLMN list. Assuming the PLMN to which cell a belongs is PLMN1, then PLMN1 is included in the RPLMN list. PLMN1 sends its EPLMN list to the terminal through base station A. The PLMNs included in the EPLMN list are equivalent to the PLMNs in the terminal's RPLMN list. Assuming the EPLMN list includes PLMN2, PLMN2 is equivalent to PLMN1.

[0095] After successful emergency registration, an emergency bearer is established between the terminal and the network. Once established, the terminal can make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time.

[0096] S502, when the terminal detects that the signal strength of the serving cell is less than or equal to the first threshold, it determines at least one candidate neighbor cell through neighbor cell signal measurement.

[0097] During the emergency bearer period, the terminal monitors the signal strength of its serving cell, i.e., cell a, in real time. If the terminal moves, for example, moving away from base station A, the signal strength of the serving cell received by the terminal weakens. When the signal strength of the serving cell is less than or equal to a first threshold, the terminal performs neighbor cell signal measurement to determine one or more candidate neighbor cells. The signal strength of each candidate neighbor cell is greater than the first threshold, i.e., the signal strength of each candidate neighbor cell is greater than the signal strength of the serving cell. For example, the first threshold can be -75dBm, and when the signal strength of the serving cell is less than or equal to -75dBm, the terminal can perform neighbor cell signal measurement to determine one or more candidate neighbor cells, and the signal strength of each candidate neighbor cell is greater than -75dBm; the first threshold can also be -80dBm, and when the signal strength of the serving cell is less than or equal to -80dBm, the terminal can perform neighbor cell signal measurement to determine one or more candidate neighbor cells, and the signal strength of each candidate neighbor cell is greater than -80dBm.

[0098] S503, the terminal determines that there is no neighboring cell among at least one candidate neighboring cell that meets the emergency carrying conditions, and continues to camp on the current serving cell.

[0099] If at least one candidate neighboring cell does not contain a cell within PLMN1, nor a cell within PLMN2; or, at least one candidate neighboring cell does not contain a cell within PLMN1, but a cell within PLMN2 exists, however, the cell within PLMN2 does not support emergency bearer; or, at least one candidate neighboring cell does not contain a cell within PLMN2, but a cell within PLMN1 exists, however, the cell within PLMN1 does not support emergency bearer, then the terminal can determine that there is no neighboring cell among the candidate neighboring cells that meets the emergency bearer conditions. When the signal strength of the serving cell is greater than or equal to a second threshold, the terminal can continue to camp on the current serving cell. For example, the second threshold can be -100dBm, meaning the terminal can continue to camp on the current serving cell when the signal strength of the serving cell is greater than or equal to -100dBm; or the second threshold can be -105dBm, meaning the terminal can continue to camp on the current serving cell when the signal strength of the serving cell is greater than or equal to -105dBm, to avoid the terminal's emergency bearer being released due to cell change. During the period when the terminal's emergency bearer exists, the network-side PSAP can obtain the terminal's accurate location in real time.

[0100] In some embodiments, after a terminal successfully completes emergency registration, a periodic registration update timer, such as the T3512 timer, can be started. After the T3512 timer expires, the terminal's emergency bearer can be released. If the terminal still needs to perform emergency services after the emergency bearer is released, it can re-initiate emergency registration. The T3512 timer has a relatively long duration, such as 54 minutes or 1 hour.

[0101] In another embodiment, the terminal can perform a cell change when a neighboring cell from the RPLMN list is available in the surrounding environment. For example, as... Figure 6 As shown, in this embodiment, the interaction process between the terminal and the base station may include the following steps:

[0102] S601, the terminal sends an emergency registration request to base station A.

[0103] In this context, base station A is the serving cell of the terminal, and the cell corresponding to base station A is cell a, meaning cell a is the serving cell of the terminal. When the terminal needs to initiate an emergency service within the coverage area of ​​cell a corresponding to base station A, the terminal can initiate an emergency registration with the PLMN to which cell a belongs through base station A. That is, the terminal can send an emergency registration request to base station A, and base station A will forward the terminal's emergency registration request to the core network corresponding to the PLMN to which cell a belongs.

[0104] S602, Base station A sends a registration success notification to the terminal.

[0105] After successful emergency registration, the core network of the PLMN to which cell a belongs can send a registration success notification to the terminal via base station A. This notification may not include the EPLMN list. Assuming cell a belongs to PLMN1, which is a PLMN that the terminal has successfully registered with, PLMN1 can be stored in the terminal's RPLMN list.

[0106] After successful emergency registration, an emergency bearer is established between the terminal and the network. Once established, the terminal can make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time.

[0107] S603, the terminal monitors the signal strength of cell a corresponding to base station A, and when the signal strength of cell a is less than or equal to a first threshold, it determines at least one candidate neighbor cell through neighbor cell signal measurement.

[0108] During the emergency bearer period, the terminal monitors the signal strength of cell a in real time. If the terminal moves, for example, moving away from base station A, the signal strength of cell a received by the terminal weakens. When the signal strength of cell a is less than or equal to a first threshold, the terminal performs neighbor cell signal measurement to determine at least one candidate neighbor cell. The signal strength of each candidate neighbor cell is greater than the first threshold.

[0109] S604, the terminal determines that cell b among the candidate neighbor cells meets the emergency carrying conditions.

[0110] Assuming the candidate neighboring cells include cell b, cell b has a signal strength of -70dBm, and cell b belongs to the same PLMN as cell a (PLMN1), and cell b supports IMS emergency bearer, then the terminal can determine that cell b meets the emergency bearer condition. Cell b and cell a can be of the same technology standard. For example, base station B corresponding to cell b and base station A corresponding to cell a both belong to the 4G mobile communication system; or, base station B corresponding to cell b and base station A corresponding to cell a both belong to the 5G mobile communication system; or, base station B corresponding to cell b and base station A corresponding to cell a both belong to a future evolution communication system. Cell b and cell a can also be of different technologies. For example, base station B corresponding to cell b belongs to the 4G mobile communication system, and base station A corresponding to cell a both belong to the 5G mobile communication system; or, base station B corresponding to cell b belongs to the 5G mobile communication system, and base station A corresponding to cell a both belong to the 4G mobile communication system.

[0111] S605, the terminal establishes a connection with base station B.

[0112] S606, the terminal disconnected from base station A.

[0113] Among them, base station B is the base station corresponding to cell b. When the terminal determines that cell b meets the emergency carrying conditions, it can change the serving cell to cell b.

[0114] In some embodiments, it is assumed that the candidate neighboring cells include cell b, cell d, and cell e. Cell b belongs to PLMN1 and supports IMS emergency bearer; cell d belongs to PLMN1, but does not support IMS emergency bearer; cell e belongs to PLMN3, which is not included in the terminal's RPLMN list. Therefore, cell b meets the emergency bearer condition, while cells d and e do not. The signal strength of cell d is -60dBm, cell e is -65dBm, and cell b is -70dBm. The candidate neighboring cells are sorted by signal strength as follows: cell d > cell e > cell b. Since cells d and e do not meet the emergency bearer condition, the terminal can change its serving cell to cell b. Because cell b belongs to PLMN1, which is included in the terminal's RPLMN list, and cell b supports IMS emergency bearer, the terminal's emergency bearer can continue to exist and will not be released after the terminal changes its serving cell from cell a to cell b.

[0115] When changing serving cells, the terminal can disconnect from base station A corresponding to cell a and establish a connection with base station B corresponding to cell b. That is, step S606 can be executed before step S605, or steps S606 and S605 can be executed simultaneously. The process of the terminal disconnecting from base station A includes one or more interactions between the terminal and base station A to transmit the information required for disconnection. Figure 6 The diagram uses double arrows to represent this. The process of establishing a connection between the terminal and base station B includes one or more interactions between the terminal and base station B, transmitting the information required to establish the connection. Figure 6 Double arrows are also used to represent this.

[0116] In another embodiment, the terminal can perform a cell change when a selectable neighboring cell from the EPLMN list exists in the surrounding environment. For example, as... Figure 7 As shown, in this embodiment, the interaction process between the terminal and the base station may include the following steps:

[0117] S701, the terminal sends an emergency registration request to base station A.

[0118] In this context, base station A is the serving cell of the terminal, and the cell corresponding to base station A is cell a, meaning cell a is the serving cell of the terminal. When the terminal needs to initiate an emergency service within the coverage area of ​​cell a corresponding to base station A, the terminal can initiate an emergency registration with the PLMN to which cell a belongs through base station A. That is, the terminal can send an emergency registration request to base station A, and base station A will forward the terminal's emergency registration request to the core network corresponding to the PLMN to which cell a belongs.

[0119] S702, Base station A sends a registration success notification to the terminal, which includes an EPLMN list.

[0120] After successful emergency registration, the core network corresponding to the PLMN of cell a can send a registration success notification to the terminal via base station A. This notification may include an EPLMN list. Upon receiving the notification, the terminal can extract and save the EPLMN list. Assuming cell a belongs to PLMN1, which is a PLMN successfully registered by the terminal, PLMN1 can be saved in the terminal's RPLMN list. PLMNs included in the EPLMN list are equivalent to PLMNs in the terminal's RPLMN list. Assuming the EPLMN list includes PLMN2, PLMN2 is equivalent to PLMN1.

[0121] After successful emergency registration, an emergency bearer is established between the terminal and the network. Once established, the terminal can make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time.

[0122] S703, the terminal monitors the signal strength of cell a corresponding to base station A, and when the signal strength of cell a is less than or equal to a first threshold, it determines at least one candidate neighbor cell through neighbor cell signal measurement.

[0123] During the emergency bearer period, the terminal monitors the signal strength of cell a in real time. If the terminal moves, for example, moving away from base station A, the signal strength of cell a received by the terminal weakens. When the signal strength of cell a is less than or equal to a first threshold, the terminal performs neighbor cell signal measurement to determine at least one candidate neighbor cell. The signal strength of each candidate neighbor cell is greater than the first threshold.

[0124] S704, the terminal determines that cell c among the candidate neighbor cells meets the emergency carrying conditions.

[0125] Assuming the candidate neighboring cells include cell c, cell c has a signal strength of -68dBm, cell c belongs to PLMN2, and cell c supports IMS emergency bearer, then the terminal can determine that cell c meets the emergency bearer conditions. Cell c and cell a can be of the same technology standard. For example, the base station C corresponding to cell c and the base station A corresponding to cell a both belong to the 4G mobile communication system; or, the base station C corresponding to cell c and the base station A corresponding to cell a both belong to the 5G mobile communication system; or, the base station C corresponding to cell c and the base station A corresponding to cell a both belong to a future evolution communication system. Cell c and cell a can also be of different technologies. For example, the base station C corresponding to cell c belongs to the 4G mobile communication system, and the base station A corresponding to cell a both belong to the 5G mobile communication system; or, the base station C corresponding to cell c belongs to the 5G mobile communication system, and the base station A corresponding to cell a both belong to the 4G mobile communication system.

[0126] S705, the terminal establishes a connection with base station C.

[0127] S706, the terminal disconnects from base station A.

[0128] Among them, base station C is the base station corresponding to cell c. When the terminal determines that cell c meets the emergency carrying conditions, it can change the serving cell to cell c.

[0129] In some embodiments, it is assumed that the candidate neighboring cells include cell c, cell d, and cell e. Cell c belongs to PLMN2 and supports IMS emergency bearer. Cell d belongs to PLMN1, which is a PLMN in the RPLMN list, but cell d does not support IMS emergency bearer. Cell e belongs to PLMN3, which is neither included in the terminal's RPLMN list nor the terminal's EPLMN list. Therefore, cell c meets the emergency bearer condition, while cells d and e do not. The signal strength of cell d is -60dBm, cell e is -65dBm, and cell b is -68dBm. The candidate neighboring cells are sorted by signal strength as follows: cell d > cell e > cell c. Since cells d and e do not meet the emergency bearer condition, the terminal can change its serving cell to cell c. Since cell c belongs to PLMN2, which is included in the terminal's EPLMN list, and cell c supports IMS emergency bearer, the terminal's emergency bearer can continue to exist and will not be released after the terminal changes its serving cell from cell a to cell c.

[0130] When changing serving cells, the terminal can disconnect from base station A corresponding to cell a and establish a connection with base station C corresponding to cell c. That is, step S706 can be executed before step S705, or steps S706 and S705 can be executed simultaneously. The process of the terminal disconnecting from base station A includes one or more interactions between the terminal and base station A to transmit the information required for disconnection. Figure 7 The diagram uses double arrows to represent this. The process of establishing a connection between the terminal and base station C includes one or more interactions between the terminal and base station B, transmitting the information required to establish the connection. Figure 7 Double arrows are also used to represent this.

[0131] Since cell c belongs to PLMN2, and PLMN2 is included in the terminal's EPLMN list, it is equivalent to PLMN1 belonging to cell a. Furthermore, cell c supports IMS emergency bearer. Therefore, after the terminal changes its serving cell from cell a to cell c, the terminal's emergency bearer can continue to exist and will not be released.

[0132] In another embodiment, when multiple neighboring cells that meet the emergency bearer conditions exist in the surrounding environment, the terminal can select a target neighboring cell from the multiple neighboring cells that meet the emergency bearer conditions and change from the serving cell to the target neighboring cell. For example, as... Figure 8 As shown, in this embodiment, the interaction process between the terminal and the base station may include the following steps:

[0133] S801, the terminal sends an emergency registration request to base station A.

[0134] In this context, base station A is the serving cell of the terminal, and the cell corresponding to base station A is cell a, meaning cell a is the serving cell of the terminal. When the terminal needs to initiate an emergency service within the coverage area of ​​cell a corresponding to base station A, the terminal can initiate an emergency registration with the PLMN to which cell a belongs through base station A. That is, the terminal can send an emergency registration request to base station A, and base station A will forward the terminal's emergency registration request to the core network corresponding to the PLMN to which cell a belongs.

[0135] S802, Base station A sends a registration success notification to the terminal, which includes an EPLMN list.

[0136] After successful emergency registration, the core network corresponding to the PLMN of cell a can send a registration success notification to the terminal via base station A. This notification may include an EPLMN list. Upon receiving the notification, the terminal can extract and save the EPLMN list. Assuming cell a belongs to PLMN1, which is a PLMN successfully registered by the terminal, PLMN1 can be saved in the terminal's RPLMN list. PLMNs included in the EPLMN list are equivalent to PLMNs in the terminal's RPLMN list. Assuming the EPLMN list includes PLMN2, PLMN2 is equivalent to PLMN1.

[0137] After successful emergency registration, an emergency bearer is established between the terminal and the network. Once established, the terminal can make emergency calls. After the emergency call ends, the emergency bearer remains active for a period of time.

[0138] S803, the terminal monitors the signal strength of cell a corresponding to base station A, and when the signal strength of cell a is less than or equal to a first threshold, it determines at least one candidate neighbor cell through neighbor cell signal measurement.

[0139] During the emergency bearer period, the terminal monitors the signal strength of cell a in real time. If the terminal moves, for example, moving away from base station A, the signal strength of cell a received by the terminal weakens. When the signal strength of cell a is less than or equal to a first threshold, the terminal performs neighbor cell signal measurement to determine at least one candidate neighbor cell. The signal strength of each candidate neighbor cell is greater than the first threshold.

[0140] S804, the terminal determines that cell b and cell c among the candidate neighbor cells meet the emergency carrying conditions.

[0141] like Figure 9 As shown, assuming the candidate neighboring cells include cell b and cell c, cell b has a signal strength of -70dBm, cell c has a signal strength of -68dBm, cell b belongs to PLMN1 and supports IMS emergency bearer, and cell c belongs to PLMN2 and supports IMS emergency bearer, then the terminal can determine that cells b and c meet the emergency bearer condition. Cells b and c can be of the same or different standards as cell a.

[0142] S805, the terminal determines cell c as the target neighboring cell.

[0143] When the candidate neighbor cells include multiple neighbor cells that meet the emergency bearer conditions, the terminal can determine the target neighbor cell from among the multiple neighbor cells that meet the emergency bearer conditions based on the signal quality of each neighbor cell. For example, if the terminal determines that cell b and cell c in the candidate neighbor cells meet the emergency bearer conditions, it can determine the target neighbor cell based on the signal quality of cell b and cell c. For example, the terminal can obtain the signal quality measurement reports of cell b and cell c respectively. The signal quality measurement reports contain the signal quality of the corresponding cells. If the signal quality of cell c is better than that of cell b, the terminal can select cell c as the target neighbor cell.

[0144] S806, the terminal establishes a connection with base station C.

[0145] S807, the terminal disconnected from base station A.

[0146] In this context, base station C is the base station corresponding to cell c. When a terminal determines that cell c meets the emergency carrying conditions, it can change its serving cell to cell c. For example... Figure 9 As shown, when changing serving cells, the terminal can disconnect from base station A corresponding to cell a and establish a connection with base station C corresponding to cell c. That is, step S807 can be executed before step S806, or steps S807 and S806 can be executed simultaneously. The process of the terminal disconnecting from base station A includes one or more interactions between the terminal and base station A to transmit the information required for disconnection. Figure 8 The diagram uses double arrows to represent this. The process of establishing a connection between the terminal and base station C includes one or more interactions between the terminal and base station B, transmitting the information required to establish the connection. Figure 8 Double arrows are also used to represent this.

[0147] Since cell c belongs to PLMN2, and PLMN2 is included in the terminal's EPLMN list, it is equivalent to PLMN1 belonging to cell a. Furthermore, cell c supports IMS emergency bearer. Therefore, after the terminal changes its serving cell from cell a to cell c, the terminal's emergency bearer can continue to exist and will not be released. When users encounter emergencies, this improves their communication experience, ensures their emergency services, and allows the network to promptly call back the terminal, increasing the call-back rate for emergency calls. It also helps the network to obtain the terminal's current location in a timely manner.

[0148] Based on the same design concept as the above-described method embodiments, this application also provides a communication device. This communication device can be applied to... Figure 1 In the terminal device shown, the communication device can be used to implement the functions of the above-described method embodiments, and therefore can achieve the beneficial effects of the above-described method embodiments. For example... Figure 10As shown, the communication device 1000 may include a signal measurement module 1001 and a control block 1002.

[0149] The signal measurement module 1001 can be used to monitor the signal strength of the serving cell of the terminal during the emergency bearer existence period of the terminal; when the signal strength of the serving cell is less than or equal to a first threshold, neighbor cell signal measurement is performed to obtain at least one candidate neighbor cell; the signal strength of the candidate neighbor cell is greater than the first threshold.

[0150] The control module 1002 can be used to continue camping on the serving cell when no neighboring cell among at least one candidate neighboring cell meets the emergency bearer conditions. The emergency bearer conditions may include: the Public Land Mobile Network (PLMN) to which the candidate neighboring cell belongs is included in the specified PLMN list within the terminal, and the candidate neighboring cell supports emergency bearer. The specified PLMN list within the terminal is a list of Public Land Mobile Network (RPLMN) that the terminal has successfully registered, or an equivalent Public Land Mobile Network (EPLMN) list; the EPLMN list is the list sent by the network device after the terminal performs emergency registration.

[0151] In some embodiments, the control module 1002 can also be used to: switch from the serving cell to the first neighboring cell when there is a first neighboring cell that meets the emergency carrying conditions among at least one candidate neighboring cell.

[0152] It should be noted that, in some embodiments, the signal measurement module 1001 can be used to execute any step in the communication method, and the control module 1002 can be used to execute any step in the communication method. The steps implemented by the signal measurement module 1001 and the control module 1002 can be specified as needed. The signal measurement module 1001 and the control module 1002 respectively implement different steps in the communication method to achieve all the functions of the communication device.

[0153] In the embodiments of this application, the functional modules can be integrated into a single processor, or each module can exist physically separately, or two or more modules can be integrated into a single module. The integrated modules described above can be implemented in hardware or as software functional units.

[0154] Based on the same technical concept as the above-described method embodiments, this application also provides a communication device, which may be a terminal or a chip in a terminal. The terminal may be... Figure 1 Any of the terminal devices shown. This communication device can be used to implement the functions of the above method embodiments, and therefore can achieve the beneficial effects of the above method embodiments.

[0155] In some embodiments, the structure of the communication device 1100 can be as follows: Figure 11As shown, the system includes a processor 1101 and a memory 1102 connected to the processor 1101. The processor 1101 and the memory 1102 can be interconnected via a bus. The processor 1101 can be a general-purpose processor, such as a microprocessor, or other conventional processor. The bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into address bus, data bus, control bus, etc.

[0156] The memory 1102 can be used to store software programs and modules. The processor 1101 executes various functional applications and data processing of the communication device 1100 by running the software programs and modules stored in the memory 1102, such as the communication method provided in the embodiments of this application.

[0157] The memory 1102 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, application programs of at least one application, etc.; the data storage area may be used to store user data, etc. In addition, the memory 1102 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0158] The processor 1101 in the communication device 1100 is used to run computer instructions or programs stored in the memory 1102 to perform the functions in any of the above method embodiments. For example, the processor can be used to monitor the signal strength of the serving cell of the terminal during emergency bearer existence; when the signal strength of the serving cell is less than or equal to a first threshold, neighbor cell signal measurement is performed to obtain at least one candidate neighbor cell; the signal strength of the candidate neighbor cell is greater than the first threshold. When there is no neighbor cell among the at least one candidate neighbor cell that meets the emergency bearer conditions, the terminal continues to camp on the serving cell. In some embodiments, the processor 1101 may include one or more processing units, which may be independent devices or integrated into one or more processors. The processor 1101 may also include a controller, which can generate operation control signals according to the instruction opcode and timing signals to complete the control of instruction fetching and execution.

[0159] In one embodiment, the communication device 1100 may further include a communication module, which can be used to communicate with network devices.

[0160] In one embodiment, the communication device 1100 may further include a SIM card interface.

[0161] The SIM card interface is used to connect a SIM card. The SIM card can be inserted into or removed from the SIM card interface to make contact with the communication device. The communication device 1100 can support one or more SIM card interfaces. Multiple SIM cards can be inserted into the same SIM card interface simultaneously. The multiple SIM cards can be of the same or different types. The communication device 1100 can interact with the network through the SIM card and the communication module to realize the aforementioned functions such as emergency calls, voice calls, and data communication.

[0162] It is understood that the structures illustrated in the embodiments of this application do not constitute a specific limitation on the communication device. In other embodiments of this application, the communication device may include more or fewer components than illustrated, or combine some components, or split some components, or have different component arrangements. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0163] This application also provides a communication system, which may include a terminal and a network device, wherein the network device may be... Figure 1 The network device 110 shown can have the following structure for the communication system: Figure 1 As shown, it will not be elaborated further here.

[0164] This application also provides a computer program product comprising computer-executable instructions. In one embodiment, the computer-executable instructions are used to cause a computer to perform the functions described in the method embodiments above.

[0165] Computer-executable instructions can be stored in a computer-readable storage medium. This application also provides a computer-readable storage medium storing executable instructions. In one embodiment, the computer-executable instructions are used to cause a computer to perform the functions described in the method embodiments above.

[0166] The computer-readable storage medium provided in the embodiments of this application may be random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), register, hard disk, portable hard disk, CD-ROM, or any other form of computer-readable storage medium known in the art.

[0167] Computer-executable instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disc (DVD); or it can be a semiconductor medium, such as a solid-state drive.

[0168] In the various embodiments of this application, unless otherwise specified or logically conflicting, the terminology and / or descriptions between different embodiments are consistent and can be referenced mutually. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or units. A method, system, product, or device is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0169] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely illustrative examples of the solutions defined by the appended claims and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application.

[0170] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of this application. Therefore, if these modifications and variations of the embodiments of this application fall within the scope of the claims of this application and their equivalents, this application also intends to include these modifications and variations.

Claims

1. A communication method characterized by comprising: The method comprises: monitoring a signal strength of a serving cell of the terminal during existence of an emergency bearer of the terminal; performing neighbor cell signal measurement to obtain at least one candidate neighbor cell when the signal strength of the serving cell is less than or equal to a first threshold value; the candidate neighbor cell has a signal strength greater than the first threshold value; continuing to camp on the serving cell when there is no neighbor cell satisfying an emergency bearer condition in the at least one candidate neighbor cell.

2. The method of claim 1, wherein, The emergency bearer condition comprises: a public land mobile network (PLMN) to which the candidate neighbor cell belongs is contained in a specified PLMN list in the terminal, and the candidate neighbor cell supports emergency bearer.

3. The method of claim 2, wherein, The specified PLMN list in the terminal is a registered public land mobile network (RPLMN) list or an equivalent public land mobile network (EPLMN) list; the EPLMN list is a list sent by a network device after the terminal performs emergency registration.

4. The method according to any one of claims 1 to 3, characterized in that, The continuing to camp on the serving cell comprises: continuing to camp on the serving cell when the signal strength of the serving cell is greater than or equal to a second threshold value; the second threshold value is less than the first threshold value.

5. The method according to any one of claims 1 to 4, characterized in that, The method further comprises: changing from the serving cell to a first neighbor cell satisfying the emergency bearer condition when the first neighbor cell exists in the at least one candidate neighbor cell.

6. The method of claim 5, wherein, The at least one candidate neighbor cell further comprises a second neighbor cell not satisfying the emergency bearer condition; the signal strength of the second neighbor cell is greater than that of the first neighbor cell.

7. A communication device, characterized by The apparatus comprises: a signal measurement module configured to monitor a signal strength of a serving cell of the terminal during existence of an emergency bearer of the terminal; and perform neighbor cell signal measurement to obtain at least one candidate neighbor cell when the signal strength of the serving cell is less than or equal to a first threshold value; the candidate neighbor cell has a signal strength greater than the first threshold value; a control module configured to continue to camp on the serving cell when there is no neighbor cell satisfying an emergency bearer condition in the at least one candidate neighbor cell.

8. The apparatus of claim 7, wherein, The emergency bearer condition comprises: a public land mobile network (PLMN) to which the candidate neighbor cell belongs is contained in a specified PLMN list in the terminal, and the candidate neighbor cell supports emergency bearer.

9. The apparatus of claim 7 or 8, wherein, The control module is further configured to: change from the serving cell to a first neighbor cell satisfying the emergency bearer condition when the first neighbor cell exists in the at least one candidate neighbor cell.

10. A communications device, characterized by The communication apparatus comprises a processor and a memory; the memory is configured to store program instructions; the processor is configured to execute the program instructions to cause the communication apparatus to perform the method in any one of claims 1 to 6.

11. A computer readable storage medium, characterized in that, The computer storage medium stores computer readable instructions; when the computer readable instructions are executed on a communication apparatus, the method in any one of claims 1 to 6 is executed.

12. A computer program product, characterised in that, When the computer program product is executed on a communication apparatus, the communication apparatus performs the method in any one of claims 1 to 6.

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