Communication method and apparatus, and storage medium and program product

Abstract

The present application relates to the technical field of communications. Disclosed are a communication method and apparatus, and a storage medium and a program product. The method comprises: a terminal device determining that first RAT in a first PLMN is unavailable; the terminal device sending first information to a core network device, wherein the first information indicates that the first RAT in the first PLMN is unavailable; the core network device sending fourth information to an access network device, wherein the fourth information indicates that the first RAT in the first PLMN is unavailable; and the access network device determining, on the basis of the fourth information, not to hand over or redirect to the first RAT in the first PLMN. The terminal device indicates that the first RAT in the first PLMN is unavailable, such that a network is not handed over or redirected to the first RAT in the first PLMN, but can be handed over or redirected to first RAT in other PLMNs, and the network can control the mobility of the terminal device at a granularity of the PLMN and the RAT, thereby improving the flexibility of network control.

Description

Communication methods, devices, storage media and software products

[0001] This application claims priority to Chinese Patent Application No. 202411906895.5, filed on December 20, 2024, entitled "Communication Method, Apparatus, Storage Medium and Program Product", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technology, and in particular to a communication method, apparatus, storage medium, and program product. Background Technology

[0003] The terminal device configuration prioritizes providing voice services, therefore it will only register with networks that offer such services. The terminal device will not connect to radio access technology (RAT) (also known as network standard) that does not provide voice services.

[0004] If a terminal device detects that voice service is unavailable under a certain RAT, it will trigger the disabling of that RAT, causing any network using that RAT to become unavailable to that terminal device. This method lacks flexibility. Summary of the Invention

[0005] This application provides a communication method, apparatus, storage medium, and program product that, by indicating that a first RAT in a first public land mobile network (PLMN) is unavailable, prevents the network from switching or redirecting to the first RAT in the first PLMN, but allows switching or redirection to the first RAT in other PLMNs, thereby improving the flexibility of network control.

[0006] Firstly, a communication method is provided, which can be executed by a terminal device or a module applied to a terminal device. The following description uses a terminal device as the executing entity.

[0007] In this method, the terminal device determines that the first RAT in the first PLMN is unavailable; and sends a first message indicating that the first RAT in the first PLMN is unavailable.

[0008] In one possible design, the method further includes: the terminal device setting the first RAT in the first PLMN to be unavailable, or de-enabling the first RAT in the first PLMN.

[0009] In another possible design, the first information includes the identifier of the first RAT.

[0010] By using this design, by carrying the identifier of the first RAT in the first information, the core network equipment can clearly identify which RAT in the current PLMN is unavailable.

[0011] In another possible design, the first information may also include the identifier of the first PLMN.

[0012] By adopting this design, by carrying the identifier of the first PLMN in the first information, the core network equipment can clearly identify which RAT in the current PLMN is unavailable.

[0013] In another possible design, the first information also indicates a first duration during which the first RAT in the first PLMN is unavailable.

[0014] In existing technologies, the process of the first RAT in the first PLMN going from available to unavailable, or from unavailable to available, requires waiting for the terminal device to enter an idle state before notifying the core network device through a registration process. With this design, the terminal device can notify the network in real time whether the first RAT in the first PLMN is available, or even without notifying the network, the network can update according to the first time interval.

[0015] In another possible design, the first information is carried in a first request, which is used to request registration or access to the network.

[0016] In another possible design, the method further includes: the terminal device and the network negotiating whether both support a first feature, the first feature indicating whether to enable the first RAT of the first PLMN.

[0017] To prevent compatibility issues, the terminal device needs to negotiate with the network device to determine whether both support the first feature. If both the terminal device and the network device support disabling the first RAT in the first PLMN, the terminal device sends a first message and sets the first RAT in the first PLMN to be unavailable, or disables the first RAT in the first PLMN.

[0018] In another possible design, when the terminal device moves to the second PLMN, the method further includes: receiving second information; and switching to the first RAT of the second PLMN based on the second information, or reselecting to the first RAT of the second PLMN.

[0019] In another possible design, the second information indicates access to the second PLMN based on the first RAT.

[0020] Secondly, a communication method is provided, executed by a core network device or a module applied to a core network device. The following description uses the core network device as the executing entity.

[0021] In this method, the core network device receives first information from the terminal device, the first information indicating that the first RAT in the first PLMN is unavailable; and sends fourth information to the access network device.

[0022] In one possible design, the fourth information indicates that the first RAT in the first PLMN is unavailable.

[0023] In another possible design, the first information includes the identifier of the first RAT.

[0024] In another possible design, the first information may also include the identifier of the first PLMN.

[0025] In another possible design, the first information also indicates a first duration during which the first RAT in the first PLMN is unavailable.

[0026] In another possible design, the fourth information also indicates a first duration during which the first RAT in the first PLMN is unavailable.

[0027] In another possible design, the method further includes: upon receiving the first information, starting a first timer, the duration of which is the first duration; and upon the first timer timing out, sending a fifth message, the fifth message instructing the access network device to delete the information indicating that the first RAT is unavailable in the first PLMN.

[0028] In existing technologies, the transition of the first RAT in the first PLMN from available to unavailable, or from unavailable to available, requires waiting for the terminal device to enter an idle state before notifying the core network device through a registration process. With this design, the terminal device can notify the network in real time whether the first RAT in the first PLMN is available, or even without notifying the network, the network can update according to a first duration. By indicating a first duration of unavailability for the first RAT in the first PLMN, the terminal device enables the core network device to start a first timer based on this first duration, promptly updating the access network device with information on the availability or unavailability of the first RAT in the first PLMN, thus improving network reliability.

[0029] In another possible design, the first information is carried in a first request, which is used to request registration or access to the network.

[0030] In another possible design, the method further includes: negotiating with the terminal device whether both support a first feature, the first feature indicating to enable the first RAT of the first PLMN.

[0031] Thirdly, a communication method is provided, which is executed by an access network device or a module applied to an access network device. The following description takes the access network device as the executing entity.

[0032] In this method, the access network device receives fourth information indicating that the first RAT in the first PLMN is unavailable; and based on the fourth information, determines not to switch or redirect to the first RAT in the first PLMN.

[0033] In one possible design, the fourth information includes the identifier of the first RAT.

[0034] In another possible design, the fourth information may also include the identifier of the first PLMN.

[0035] In another possible design, when the terminal device moves to the second PLMN, the method further includes: the access network device sending second information based on the fourth information, the second information indicating access to the second PLMN based on the first RAT; and receiving third information for requesting access to the second PLMN based on the first RAT.

[0036] In another possible design, the fourth information also indicates a first duration during which the first RAT in the first PLMN is unavailable; the method further includes: upon receiving the fourth information, starting a second timer, the duration of which is the first duration; and upon the second timer timing out, if the terminal device is in the first PLMN, sending a sixth information, the sixth information indicating access to the first PLMN based on the first RAT.

[0037] In existing technologies, the transition of the first RAT in the first PLMN from available to unavailable, or from unavailable to available, requires waiting for the terminal device to enter an idle state before notifying the core network device through a registration process. With this design, the terminal device can notify the network in real time whether the first RAT in the first PLMN is available, or even without notifying the network, the network can update according to a first duration. By indicating a first duration of unavailability of the first RAT in the first PLMN, the terminal device enables the access network device to start a second timer based on this first duration. If the second timer expires, and the terminal device is in the first PLMN, the access network device can promptly trigger the handover of the first RAT in the first PLMN.

[0038] Fourthly, a communication device is provided. The communication device can perform the methods described in the first to third aspects or any one of the designs described in the first to third aspects. The communication device can be a terminal device or a network device, or it can be a module (e.g., a chip) applied in a terminal device or a module (e.g., a chip) applied in a network device.

[0039] In one possible design, the communication device includes a transceiver unit and a processing unit. The transceiver unit performs the receiving and / or transmitting operations in the methods of the first to third aspects or any one of the designs described above; the processing unit performs the processing operations in the methods of the first to third aspects or any one of the designs described above.

[0040] In another possible design, the communication device includes a processor coupled to a memory; the processor is configured to support the device in performing the corresponding functions in the channel state information reporting method described above. The memory, coupled to the processor, stores the necessary computer programs (or computer-executable instructions) and / or data of the device. Optionally, the communication device may further include a communication interface for supporting communication between the device and other network elements, such as the transmission or reception of data and / or signals. Exemplarily, the communication interface may be a transceiver, circuit, bus, module, or other type of communication interface. Optionally, the memory may be located internally within the communication device and integrated with the processor; alternatively, it may be located externally to the communication device.

[0041] In another possible design, the communication device includes a processor and a transceiver, the processor being coupled to the transceiver. The processor executes computer programs or instructions to control the transceiver to receive and send information. When the processor executes the computer programs or instructions, it is also used to design the above-mentioned method through logic circuits or execution code instructions. The transceiver can be a transceiver circuit, a transceiver module, or an input / output interface, used to receive signals from other communication devices besides the communication device and transmit them to the processor, or to send signals from the processor to other communication devices besides the communication device. When the communication device is a chip, the transceiver is a transceiver circuit or an input / output interface.

[0042] When the communication device is a chip, the transmitting unit can be an output unit, such as an output circuit or a communication interface; the receiving unit can be an input unit, such as an input circuit or a communication interface. When the communication device is a terminal device, the transmitting unit can be a transmitter or a receiver; the receiving unit can be a receiver or a receiver.

[0043] Fifthly, a computer-readable storage medium is provided that stores a computer program or instructions thereon, which, when executed by a communication device, implement the method as described in the first aspect or any design of the first aspect, or implement the method as described in the second aspect or any design of the second aspect, or implement the method as described in the third aspect or any design of the third aspect.

[0044] A sixth aspect provides a computer program product that, when executed on a communication device, implements the method as described in the first aspect or any design of the first aspect, or implements the method as described in the second aspect or any design of the second aspect, or implements the method as described in the third aspect or any design of the third aspect. Attached Figure Description

[0045] Figure 1 is a schematic diagram of the architecture of the communication system 1000 used in the embodiments of this application;

[0046] Figures 2-5 are schematic diagrams of the existing disabled network process;

[0047] Figures 6-13 are schematic flowcharts of the communication method provided in the embodiments of this application;

[0048] Figures 14 and 15 are schematic diagrams of the communication device provided in the embodiments of this application. Detailed Implementation

[0049] Figure 1 is a schematic diagram of the architecture of a communication system 1000 provided in an embodiment of this application. As shown in Figure 1, the communication system 1000 includes a radio access network (RAN) 100, wherein the RAN 100 includes at least one RAN node (110a and 110b in Figure 1, collectively referred to as 110), and may also include at least one terminal device (120a-120j in Figure 1, collectively referred to as 120). The RAN 100 may also include other RAN nodes, such as wireless relay devices and / or wireless backhaul devices (not shown in Figure 1). The terminal device 120 is wirelessly connected to the RAN node 110. Terminal devices and RAN nodes can be interconnected via wired or wireless means. The communication system 1000 may also include a core network 200. The RAN node 110 is connected to the core network 200 via wireless or wired means. The core network equipment in core network 200 and the RAN node 110 in RAN 100 can be independent and different physical devices, or they can be the same physical device that integrates the logical functions of the core network equipment and the logical functions of the RAN node. Communication system 1000 may also include Internet 300.

[0050] RAN100 can be an evolved universal terrestrial radio access (E-UTRA) system, a new radio (NR) system, or a future radio access system as defined in the 3rd generation partnership project (3GPP), or it can be a WiFi system. RAN100 can also include two or more of the above-mentioned different radio access systems. RAN100 can also be an open RAN (O-RAN).

[0051] RAN nodes, also known as radio access network devices, RAN entities, or access nodes, are used to help terminal devices access communication systems wirelessly. In one application scenario, an RAN node can be a base station, an evolved NodeB (eNodeB), a transmission and reception point (TRP), a next-generation NodeB (gNB) in a 5G mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system. RAN nodes can be macro base stations (as shown in Figure 1, 110a), micro base stations or indoor stations (as shown in Figure 1, 110b), relay nodes, or donor nodes.

[0052] In another application scenario, multiple RAN nodes can collaborate to help terminal devices achieve wireless access, with different RAN nodes implementing different functions of the base station. For example, a RAN node can be a central unit (CU), a distributed unit (DU), or a radio unit (RU). Here, the CU performs the functions of the base station's Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP), and can also perform the functions of the Service Data Adaptation Protocol (SDAP). The DU performs the functions of the base station's Radio Link Control (RANC) and Medium Access Control (MAC) layers, and can also perform some or all of the physical layer functions. For specific descriptions of these protocol layers, refer to the relevant 3GPP technical specifications. The RU can be used to implement radio frequency signal transmission and reception. The CU and DU can be two independent RAN nodes or integrated into the same RAN node, such as within a baseband unit (BBU). The RU can be included in radio frequency equipment, such as in a remote radio unit (RRU) or an active antenna unit (AAU). The CU can be further divided into two types of RAN nodes: CU-control plane and CU-user plane.

[0053] In different systems, RAN nodes may have different names. For example, in an O-RAN system, a CU can be called an open CU (O-CU), a DU can be called an open DU (O-DU), and an RU can be called an open RU (O-RU). The RAN nodes in the embodiments of this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules. For example, a RAN node can be a server loaded with the corresponding software modules. The embodiments of this application do not limit the specific technology or device form used in the RAN nodes. For ease of description, a base station is used as an example of a RAN node in the following description.

[0054] A terminal device is a device with wireless transceiver capabilities, capable of sending signals to or receiving signals from a base station. Terminal devices can also be referred to as terminals, user equipment (UE), mobile stations, mobile terminal devices, etc. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), the Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminal devices can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, airplanes, ships, robots, robotic arms, smart home devices, etc. The embodiments of this application do not limit the specific technologies or device forms used in the terminal devices.

[0055] Base stations and terminal equipment can be fixed 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 on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the base stations and terminal equipment.

[0056] The roles of base stations and terminal devices can be relative. For example, the helicopter or drone 120i in Figure 1 can be configured as a mobile base station. For terminal devices 120j that access the wireless access network 100 through 120i, terminal device 120i is a base station; however, for base station 110a, 120i is a terminal device, meaning that 110a and 120i communicate via a wireless air interface protocol. Of course, 110a and 120i can also communicate via a base station-to-base station interface protocol. In this case, relative to 110a, 120i is also a base station. Therefore, both base stations and terminal devices can be collectively referred to as communication devices. 110a and 110b in Figure 1 can be called communication devices with base station functions, and 120a-120j in Figure 1 can be called communication devices with terminal device functions.

[0057] Communication between base stations and terminal devices, between base stations, and between terminal devices can be conducted using licensed spectrum, unlicensed spectrum, or both simultaneously. Communication can be conducted using spectrum below 6 GHz, spectrum above 6 GHz, or both simultaneously. The embodiments of this application do not limit the spectrum resources used for wireless communication.

[0058] In the embodiments of this application, 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, including base station 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 device functions.

[0059] In this application, the base station sends downlink signals or downlink information to the terminal device, with the downlink information carried on the downlink channel; the terminal device sends uplink signals or uplink information to the base station, with the uplink information carried on the uplink channel. To communicate with the base station, the terminal device needs to establish a radio connection on a cell controlled by the base station. The cell with which the terminal device has established a radio connection is called the serving cell of the terminal device. When the terminal device communicates with this serving cell, it is also subject to interference from signals from neighboring cells.

[0060] The terminal device configuration prioritizes providing voice services, thus favoring networks that offer such services for registration. Terminal devices will not connect to RATs that cannot provide voice services; they will disable RAT networks that lack voice services. For example, if LTE cannot provide voice services, the Long Term Evolution (LTE) network will be disabled (called LTE disable); similarly, if NR cannot provide voice services, the NR network will be disabled (called NR disable). The purpose of disabling networks is twofold: 1. To prevent terminal devices from reselecting to networks that cannot provide voice services; 2. To inform the core network through the terminal device's capabilities that certain RATs are not supported, preventing the network from redirecting or handovering the terminal device to a network that cannot provide voice services.

[0061] Figure 2 illustrates a typical network deactivation process. In step S201, the terminal device deactivates NR. For example, if a voice-centric terminal device experiences IMS voice service unavailability or registration failure under NR, NR deactivation is triggered. Then, in step S202, the terminal searches for an LTE network. If the LTE network search is successful, the terminal notifies the network during LTE registration that it does not support NR. The terminal then sends a Long Term Evolution (LTE) Attack Request to the Mobile Management Entity (MME). This request indicates that N1 mode for 3GPP access is not supported, meaning NR is not supported. Next, in step S203, the MME sends an Initial Context Setup Request to the LTE RAN. This request includes the terminal device's security capabilities and radio capabilities. The MME forwards information about the terminal device's radio access capabilities (UERadioAccessCapabilityInformation) to the LTE access network, specifically the terminal device's radio access capability information, indicating that the terminal device does not support NR. Therefore, because the N1 mode is not supported, the LTE access network will not trigger a handover between PLMNs, preventing the terminal device from being unable to initiate voice calls after handover or redirection to NR.

[0062] However, according to the process shown in Figure 2, temporary IMS unavailability may lead to NR deactivation; or the temporary abnormal cause value reaching the maximum number during registration may also lead to NR deactivation. The above situation may only be a problem of a single network (a certain PLMN), while other networks (other PLMNs) are available. For example, as shown in Figure 3, which is a schematic diagram of another existing network deactivation process, in step S301, the NR in PLMN1 is deactivated due to a temporary reason. In step S302, the terminal searches for the LTE network. The LTE network search is successful, and during LTE registration, the terminal device is notified to the network that it does not support NR. The terminal device then sends a Long Term Evolution Access Request to the MME, which indicates that it does not support the N1 mode for 3G Partner Program access, i.e., it does not support NR. Then, in step S303, the MME sends an Initial Context Establishment Request to the LTE-RAN. This request includes the terminal device's security capabilities, radio capabilities, and radio access capability information. That is, the MME forwards the information that the terminal device does not support NR to the LTE access network. Therefore, even if the terminal device moves to the NR in PLMN2, the LTE access network will not trigger the handover between PLMNs because it does not support N1 mode. During the service process, it cannot notify the network of the terminal device's capability change through registration. Since the network believes that the UE does not support NR at this time, it cannot switch to the NR in PLMN2.

[0063] Figure 4 shows a schematic diagram of another existing de-enabled network process. Steps S401 to S403 can refer to steps S201 to S203 in Figure 2. The difference is that in step S404, the de-enabled penalty timer times out, and then proceeds to step S405. The terminal device sends a second Long Term Evolution Access Request to the MME. This request indicates support for N1 mode for 3GPP access, i.e., support for NR. Then, in step S406, the MME sends information indicating N1 support to the LTE-RAN. In step S407, because the terminal device supports N1 mode and NR capability, the LTE-RAN triggers a handover between PLMNs.

[0064] However, as shown in Figure 5, which illustrates another existing de-enabled network process, in step S501, due to five failed registration attempts, the terminal device sends a de-enabled NR indication to the new radio access network (NR-RAN). Then, in step S502, the terminal device successfully accesses LTE and triggers a scheduling request (SR) to the LTE-RAN. In step S503, the terminal device enters the connected state (EMM-CONNECTED), the de-enabled NR penalty timer times out, delaying NR enabling. If the NR remains de-enabled, the handover between PLMNs fails because it does not support N1 mode. It can be seen that the NR in PLMN1 is de-enabled for temporary reasons, but registration on LTE is successful (carrying the unsupported NR capability), and data services are initiated. The de-enabled NR penalty timer times out, and during service, the terminal device cannot inform the network of the capability change through registration (currently, the terminal device notifies the core network of its unsupported RAT through its capability items; the signaling overhead of the terminal device's capability items is large, requiring the terminal device's capability items to be sent to the core network through the network registration process). At this point, the network still believes that the terminal device does not support NR, which prevents it from switching to NR in PLMN1.

[0065] To address the following issues in Figures 2 and 3: When the NR in PLMN1 is temporarily disabled, the network is notified during LTE registration that the terminal device does not support NR. Even if the terminal device moves to the NR in PLMN2, the network considers the UE not to support NR, resulting in an inability to switch to the NR in PLMN2. This application provides a communication scheme whereby the terminal device indicates that the first RAT in the first PLMN is unavailable, preventing the network from switching or redirecting to the first RAT in the first PLMN. However, the network can switch or redirect to the first RAT in other PLMNs. The network can control the mobility of the terminal device at the granularity of PLMN and RAT, improving the flexibility of network control.

[0066] Based on the above-described communication system, the communication method provided by the embodiments of this application is described below:

[0067] This application relates to the interaction between terminal devices, access network devices, and core network devices. In this embodiment, the operations performed by the terminal device can be executed by the terminal device itself or by modules applied to the terminal device. The modules of the terminal device can be communication modules within the terminal device, or circuits or chips applied to the terminal device (such as modem chips, baseband chips, or system-on-chip (SoC) chips or system-in-package (SIP) chips containing modem cores). The operations performed by the access network device can be executed by the access network device itself or by modules applied to the access network device. The modules of the access network device can be communication modules within the access network device, or circuits or chips applied to the access network device (such as modem chips), or SoC chips or SIP chips containing modem cores. The operations performed by the core network device can be executed by the core network device itself or by modules applied to the core network device. The modules of the core network device can be communication modules within the core network device, or circuits or chips applied to the core network device (such as modem chips), or SoC chips or SIP chips containing modem cores.

[0068] Figure 6 shows a flowchart of a communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0069] S601. Whether the terminal device and the network both support the first feature.

[0070] The first characteristic indicates the first RAT of the first PLMN to be enabled.

[0071] Supporting the first feature means enabling the first RAT while simultaneously enabling the first PLMN.

[0072] To prevent compatibility issues, if both the terminal device and the network device support the first feature (negotiation successful), the subsequent process of this embodiment will be implemented; if the terminal device or the network does not support the first feature (negotiation fails), the existing process shown in Figure 2 or Figure 4 above can be used.

[0073] Alternatively, it can be assumed that both the terminal device and the network device support the first feature. Therefore, this step is optional and is shown as a dashed line in Figure 6.

[0074] For example, the first RAT can be of the LTE, NR, or other standards.

[0075] S602. The terminal device determines that the first RAT in the first PLMN is unavailable.

[0076] For example, if the IMS voice service under the first RAT in the first PLMN is unavailable or registration fails, the terminal device determines that the first RAT in the first PLMN is unavailable.

[0077] S603. The terminal device disables the first RAT in the first PLMN.

[0078] Alternatively, the terminal device can be configured to disable the first RAT in the first PLMN.

[0079] Alternatively, the terminal device may not perform the step of disabling or setting the first RAT in the first PLMN to be unavailable, but instead enable or set the first RAT in the first PLMN to be unavailable through other means (e.g., hardware). Therefore, this step is optional and is shown as a dashed line in Figure 6.

[0080] S604. The terminal device sends the first information to the core network device.

[0081] Accordingly, the core network equipment receives this first information.

[0082] If the terminal device determines that the first RAT in the first PLMN is unavailable, it sends a first message to the core network device. This first message indicates that the first RAT in the first PLMN is unavailable.

[0083] For example, the first information may include the identifier of the first RAT. By carrying the identifier of the first RAT in the first information, the core network device can clearly determine that the first RAT in the PLMN (registered PLMN, RPLMN) currently registered by the terminal device is unavailable.

[0084] For example, the first information may further include the identifier of the first PLMN. By carrying the identifier of the first PLMN and the identifier of the first RAT in the first information, the core network equipment can clearly identify which RAT in which PLMN is unavailable. The first PLMN may be different from the PLMN currently registered by the terminal equipment.

[0085] For example, the first information mentioned above is non-access stratum (NAS) information.

[0086] In one example, the aforementioned first information is carried in a first request, which is used to request registration or access to the network. That is, the terminal device can still notify the core network device that the first RAT in the first PLMN is unavailable through a registration request or access request. However, unlike the prior art, this first information notifies that the first RAT in the first PLMN is unavailable, meaning that only the first RAT in the first PLMN is unavailable. In other words, the first RAT in other PLMNs may be available.

[0087] In another example, the terminal device can also send this first information to the core network device independently. By notifying the core network device that the first RAT in the first PLMN is unavailable independently, without relying on registration or access requests, the terminal device can provide more timely and flexible notification to the core network device.

[0088] S605. The core network equipment sends the fourth information to the access network equipment.

[0089] Accordingly, the access network device receives this fourth piece of information.

[0090] After receiving the first information, the core network device sends a fourth piece of information to the access network device. This fourth piece of information indicates that the first RAT in the first PLMN is unavailable.

[0091] S606. Based on the fourth information, the access network device determines whether to switch or redirect to the first RAT in the first PLMN.

[0092] After receiving the aforementioned fourth information, when network switching or network redirection is required, the access network device determines that the first RAT in the first PLMN is unavailable based on the aforementioned fourth information, and therefore determines not to switch or redirect to the first RAT in the first PLMN, so as to avoid switching or redirection failure.

[0093] According to an embodiment of this application, a communication method is provided in which a terminal device indicates that a first RAT in a first PLMN is unavailable, so that the network does not switch or redirect to the first RAT in the first PLMN, but can switch or redirect to the first RAT in other PLMNs. The network can control the mobility of the terminal device according to the granularity of PLMN and RAT, thereby improving the flexibility of network control.

[0094] The following description uses the example of an unavailable NR in the first PLMN and a terminal device carrying the first information via separate signaling:

[0095] Figure 7 shows a flowchart of another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0096] S701. Whether the terminal device and the network both support the first feature.

[0097] The first characteristic indicates that the NR of the first PLMN should be enabled.

[0098] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0099] S702. The terminal device determines that the NR in the first PLMN is unavailable.

[0100] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0101] S703. The terminal device disables the NR in the first PLMN.

[0102] Alternatively, the terminal device can be configured to disable the NR in the first PLMN.

[0103] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0104] S704. The terminal device sends an LTE access request to the MME.

[0105] Accordingly, the MME receives the LTE access request.

[0106] The terminal device searches for an LTE network. If the LTE network search is successful, it sends an LTE access request to the MME.

[0107] S705. The terminal device sends the first information to the MME.

[0108] Accordingly, the MME receives this first information.

[0109] The first information indicates that the NR in the first PLMN is unavailable.

[0110] The specific implementation of this step can be referred to step S604 of the embodiment shown in Figure 6, and will not be repeated here. In this embodiment, the terminal device carries the first information through separate signaling.

[0111] S706.MME sends the fourth message to LTE-RAN.

[0112] Accordingly, the LTE-RAN receives this fourth piece of information.

[0113] The fourth piece of information indicates that the NR in the first PLMN is unavailable.

[0114] For example, this fourth piece of information can be carried in the initial context establishment request.

[0115] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0116] Based on the fourth information, the S707.LTE-RAN determines whether to switch or redirect to the NR in the first PLMN.

[0117] The specific implementation of this step can be found in step S606 of the embodiment shown in Figure 6, and will not be repeated here.

[0118] S708. When the terminal equipment moves to the second PLMN, the LTE-RAN triggers a handover to the NR-RAN.

[0119] If the LTE-RAN determines that the NR in the first PLMN is unavailable, and the terminal device moves to the second PLMN, the LTE-RAN can trigger a handover to the NR-RAN, that is, trigger the terminal device to access the second PLMN based on the NR.

[0120] S709.NR-RAN sends a second message to the terminal equipment.

[0121] Accordingly, the terminal device receives the second information.

[0122] After receiving the trigger indication from the LTE-RAN, the NR-RAN sends a second message to the terminal device, wherein the second message indicates that the NR is accessing the second PLMN.

[0123] S710. The terminal device switches to the NR of the second PLMN or reselects to the NR of the second PLMN based on the second information.

[0124] After receiving the second information from the NR-RAN, the terminal device switches to the NR of the second PLMN or reselects to the NR of the second PLMN based on the second information.

[0125] According to a communication method provided in an embodiment of this application, a terminal device indicates that the NR in the first PLMN is unavailable, so that the network does not switch or redirect to the NR in the first PLMN, but can switch or redirect to the NR in other PLMNs (for example, if the terminal device moves to the second PLMN, it can switch or redirect to the second PLMN). The network can control the mobility of the terminal device according to the granularity of PLMN and RAT, thereby improving the flexibility of network control.

[0126] The following description uses the example of an unavailable NR in the first PLMN and a terminal device carrying the first information through a first request:

[0127] Figure 8 shows a flowchart of another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0128] S801. Whether the terminal device and the network both support the first feature.

[0129] The first characteristic indicates that the NR of the first PLMN should be enabled.

[0130] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0131] S802. The terminal device determines that the NR in the first PLMN is unavailable.

[0132] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0133] S803. The terminal device disables the NR in the first PLMN.

[0134] Alternatively, the terminal device can be configured to disable the NR in the first PLMN.

[0135] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0136] S804. The terminal device sends an LTE access request to the MME.

[0137] The LTE access request includes first information indicating that the NR in the first PLMN is unavailable.

[0138] The difference from the embodiment shown in Figure 7 is that in this embodiment, the terminal device carries the aforementioned first information through the LTE access request.

[0139] S805.MME sends the fourth message to LTE-RAN.

[0140] Accordingly, the LTE-RAN receives this fourth piece of information.

[0141] The fourth piece of information indicates that the NR in the first PLMN is unavailable.

[0142] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0143] Based on the fourth information, the S806.LTE-RAN determines whether to switch or redirect to the NR in the first PLMN.

[0144] The specific implementation of this step can be found in step S606 of the embodiment shown in Figure 6, and will not be repeated here.

[0145] S807. In the event that the terminal equipment moves to the second PLMN, a handover to the NR-RAN is triggered.

[0146] The specific implementation of this step can be found in step S708 of the embodiment shown in Figure 7, and will not be repeated here.

[0147] S808.NR-RAN sends the second information to the terminal equipment.

[0148] Accordingly, the terminal device receives the second information.

[0149] The second information indicates that the second PLMN is accessed via NR.

[0150] The specific implementation of this step can be referred to step S709 of the embodiment shown in Figure 7, and will not be repeated here.

[0151] S809. The terminal device switches to the NR of the second PLMN or reselects to the NR of the second PLMN based on the second information.

[0152] Accordingly, the NR-RAN receives this third information.

[0153] The specific implementation of this step can be referred to step S710 of the embodiment shown in Figure 7, and will not be repeated here.

[0154] According to a communication method provided in an embodiment of this application, a terminal device indicates that the NR in the first PLMN is unavailable, so that the network does not switch or redirect to the NR in the first PLMN, but can switch or redirect to the NR in other PLMNs (for example, if the terminal device moves to the second PLMN, it can switch or redirect to the second PLMN). The network can control the mobility of the terminal device according to the granularity of PLMN and RAT, thereby improving the flexibility of network control.

[0155] The above embodiments describe how a terminal device notifies the core network device that the first RAT in the first PLMN is unavailable. Additionally, the following embodiments will describe how this notification may also carry a first duration of the first RAT's unavailability in the first PLMN:

[0156] Figure 9 shows a flowchart of a communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0157] S901. Whether the terminal device and the network both support the first feature.

[0158] The first characteristic indicates the first RAT of the first PLMN to be enabled.

[0159] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0160] S902. The terminal device determines that the first RAT in the first PLMN is unavailable.

[0161] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0162] S903. The terminal device disables the first RAT in the first PLMN.

[0163] Alternatively, the terminal device can be configured to disable the first RAT in the first PLMN.

[0164] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0165] S904. The terminal device sends the first information to the core network device.

[0166] Accordingly, the core network equipment receives this first information.

[0167] The first information indicates that the first RAT in the first PLMN is unavailable. For a detailed implementation of this step, refer to step S604 of the embodiment shown in Figure 6.

[0168] Unlike the embodiment shown in Figure 6, this first information also indicates a first duration for which the first RAT in the first PLMN is unavailable. Since the terminal device determines that the first RAT in the first PLMN is unavailable due to temporary unavailability or registration failure of the IMS voice service under the first RAT in the first PLMN, this unavailability is temporary and has a certain time limit. The terminal device determines the first duration for which the first RAT in the first PLMN is unavailable and notifies the core network equipment of the first duration for which the first RAT in the first PLMN is unavailable.

[0169] S905. The core network equipment sends the fourth information to the access network equipment.

[0170] Accordingly, the access network device receives this fourth piece of information.

[0171] The fourth message indicates that the first RAT in the first PLMN is unavailable.

[0172] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0173] S906. Based on the fourth information, the access network device determines whether to switch or redirect to the first RAT in the first PLMN.

[0174] The specific implementation of this step can be found in step S606 of the embodiment shown in Figure 6, and will not be repeated here.

[0175] S907. When the core network device receives the first information, it starts the first timer.

[0176] When the core network device receives the first information, it starts the first timer based on the first duration during which the first RAT in the first PLMN is unavailable. The duration of the first timer is the first duration, that is, the core network device counts the time during which the first RAT in the first PLMN is unavailable.

[0177] S908. The first timer expires, and the core network device sends the fifth information to the access network device.

[0178] Accordingly, the access network equipment receives this fifth piece of information.

[0179] If the first timer times out, meaning the duration of the first timer reaches the first duration during which the first RAT in the first PLMN becomes unavailable, and the first RAT in the first PLMN becomes available, then the core network device sends a fifth message to the access network device. This fifth message instructs the access network device to delete the information indicating that the first RAT in the first PLMN is unavailable.

[0180] S909. Based on the fifth information, the access network device deletes the information that the first RAT is unavailable in the first PLMN.

[0181] In step S905 above, after receiving the fourth information, the access network device caches the information that the first RAT in the first PLMN is unavailable, and based on this information, does not trigger a handover to the first RAT in the first PLMN. After receiving the fifth information, the access network device deletes the information that the first RAT in the first PLMN is unavailable based on the fifth information. Subsequently, when the handover requirements are met, the access network device can trigger a handover to the first RAT in the first PLMN.

[0182] In existing technologies, the process of a first RAT in a first PLMN going from available to unavailable, or from unavailable to available, requires waiting for the terminal device to enter an idle state before notifying the core network device through a registration process. In this embodiment, the terminal device can notify the network in real time whether the first RAT in the first PLMN is available, or even without notifying the network, the network can update according to the first time interval.

[0183] Optionally, steps S905, S906, S908, and S909 can be omitted. Instead, when the access network device determines to perform a handover or redirection, it queries the core network device to determine whether the first RAT in the first PLMN is available. If the first timer has not expired, the access network device sends a first query request to the core network device to request whether the first RAT in the first PLMN is available. The core network device returns the first query result, indicating that the first RAT in the first PLMN is unavailable. If the first timer expires, the access network device sends a second query request to the core network device to request whether the first RAT in the first PLMN is available. The core network device returns the second query result, indicating that the first RAT in the first PLMN is available. Then, the access network device can instruct the terminal device to handover or reselect to the first PLMN based on the first RAT.

[0184] According to a communication method provided in an embodiment of this application, a terminal device indicates a first duration during which a first RAT in a first PLMN is unavailable, enabling a core network device to start a first timer based on the first duration, and promptly update the access network device with information on whether the first RAT in the first PLMN is available or unavailable, thereby improving network reliability.

[0185] The following description uses the example of NR being unavailable in the first PLMN:

[0186] Figure 10 shows a flowchart of another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0187] S1001. Does both the terminal device and the network negotiate to support the first feature?

[0188] The first characteristic indicates that the NR of the first PLMN should be enabled.

[0189] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0190] S1002. The terminal device determines that the NR in the first PLMN is unavailable.

[0191] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0192] S1003. The terminal device disables the NR in the first PLMN.

[0193] Alternatively, the terminal device can be configured to disable the NR in the first PLMN.

[0194] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0195] S1004. The terminal device sends an LTE access request to the MME.

[0196] The specific implementation of this step can be referred to step S704 of the embodiment shown in Figure 6, and will not be repeated here.

[0197] S1005. The terminal device sends the first information to the MME.

[0198] Accordingly, the MME receives this first information.

[0199] The first information indicates that the NR in the first PLMN is unavailable, and the first information also indicates the first duration for which the NR in the first PLMN is unavailable.

[0200] The specific implementation of this step can be referred to step S905 of the embodiment shown in Figure 9, and will not be repeated here.

[0201] S1006.MME sends the fourth message to LTE-RAN.

[0202] Accordingly, the LTE-RAN receives this fourth piece of information.

[0203] The fourth piece of information indicates that the NR in the first PLMN is unavailable.

[0204] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0205] S1007.LTE-RAN determines, based on the fourth information, whether to switch or redirect to the NR in the first PLMN.

[0206] The specific implementation of this step can be found in step S606 of the embodiment shown in Figure 6, and will not be repeated here.

[0207] When S1008.MME receives the first information, it starts the first timer.

[0208] The duration of the first timer is the aforementioned first duration.

[0209] The specific implementation of this step can be found in step S907 of the embodiment shown in Figure 9, and will not be repeated here.

[0210] S1009. The first timer expires. If the terminal device is in the first PLMN, the MME sends the fifth information to the LTE-RAN.

[0211] Accordingly, the LTE-RAN receives this fifth piece of information.

[0212] The fifth piece of information instructs the LTE-RAN to delete information about unavailable NRs in the first PLMN.

[0213] The specific implementation of this step can be referred to step S908 of the embodiment shown in Figure 9, and will not be repeated here.

[0214] S1010.LTE-RAN removes information about unavailable NR in the first PLMN.

[0215] The specific implementation of this step can be found in step S909 of the embodiment shown in Figure 9, and will not be repeated here.

[0216] If the LTE signal quality is below a set threshold, and the terminal device is in the NR of the first PLMN, and the LTE-RAN determines that the NR in the first PLMN is available, then the LTE-RAN can trigger a handover to the NR-RAN.

[0217] The above embodiments describe how the core network device can control the updating of information regarding the availability or unavailability of the first RAT in the first PLMN based on a first duration of unavailability of the first RAT in the first PLMN. The following embodiments will describe how the access network device can also determine, on its own, whether to trigger a handover of the first RAT in the first PLMN based on the first duration of unavailability of the first RAT in the first PLMN.

[0218] Figure 11 shows a flowchart of a communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0219] S1101. Whether the terminal device and the network both support the first feature.

[0220] The first characteristic indicates the first RAT of the first PLMN to be enabled.

[0221] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0222] S1102. The terminal device determines that the first RAT in the first PLMN is unavailable.

[0223] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0224] S1103. The terminal device disables the first RAT in the first PLMN.

[0225] Alternatively, the terminal device can be configured to disable the first RAT in the first PLMN.

[0226] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0227] S1104. The terminal device sends the first information to the core network device.

[0228] Accordingly, the core network equipment receives this first information.

[0229] The first information indicates that the first RAT in the first PLMN is unavailable, and the first information also indicates the first duration for which the first RAT in the first PLMN is unavailable.

[0230] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0231] S1105. The core network equipment sends the fourth information to the access network equipment.

[0232] Accordingly, the access network device receives this fourth piece of information.

[0233] The fourth information indicates that the first RAT in the first PLMN is unavailable, and also indicates the first duration for which the first RAT in the first PLMN is unavailable.

[0234] The specific implementation of this step can be found in step S904 of the embodiment shown in Figure 9, and will not be repeated here.

[0235] S1106. Based on the fourth information, the access network device determines not to switch or redirect to the first RAT in the first PLMN.

[0236] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0237] S1107. When the access network device receives the fourth information, it starts the second timer.

[0238] The duration of the second timer is the same as the duration of the first timer.

[0239] When the access network device receives the fourth information, it starts a second timer based on the first duration of the first RAT being unavailable in the first PLMN. The duration of the second timer is the first duration, that is, the access network device counts the time during which the first RAT in the first PLMN is unavailable.

[0240] S1108. The second timer times out. If the terminal device is in the first PLMN, the access network device triggers the handover of the first RAT in the first PLMN.

[0241] If the second timer times out (i.e., the duration of the second timer reaches a first duration during which the first RAT in the first PLMN becomes unavailable), and the first RAT in the first PLMN becomes available, then if the terminal device is in the first PLMN and the communication quality is poor when communicating using other RATs in the first PLMN, or if the signal quality is poor when the terminal device is in other PLMNs, the access network device can trigger a handover of the first RAT in the first PLMN. For example, if the terminal device is in the second PLMN before the second timer times out, the terminal device can access the network using either the first RAT or the second RAT in the second PLMN; if the terminal device is in the first PLMN, the access network device can trigger the terminal device to access the network using the first RAT in the first PLMN.

[0242] In existing technologies, for a first RAT in a first PLMN to go from available to unavailable, or from unavailable to available, it requires waiting for the terminal device to enter an idle state, then notifying the core network device through a registration process, and finally the core network device notifying the access network device. In this embodiment, the terminal device can notify the network in real time whether the first RAT in the first PLMN is available, or even without notifying the network, the network can update according to the first time interval.

[0243] According to a communication method provided in an embodiment of this application, a terminal device indicates that the first RAT in the first PLMN is unavailable for a first duration, so that the access network device can start a second timer according to the first duration. If the second timer expires and the terminal device is in the first PLMN, the access network device can promptly trigger the handover of the first RAT in the first PLMN.

[0244] The following description uses the example of an unavailable NR in the first PLMN, where the information indicating the unavailability of the NR in the first PLMN and the first duration are carried in a separate signaling message:

[0245] Figure 12 shows a flowchart of another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0246] S1201. Whether the terminal device and the network both support the first feature.

[0247] The first characteristic indicates that the NR of the first PLMN should be enabled.

[0248] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0249] S1202. The terminal device determines that the NR in the first PLMN is unavailable.

[0250] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0251] S1203. The terminal device disables the NR in the first PLMN.

[0252] Alternatively, the terminal device can be configured to disable the NR in the first PLMN.

[0253] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0254] S1204. The terminal device sends an LTE access request to the MME.

[0255] The specific implementation of this step can be referred to step S704 of the embodiment shown in Figure 7, and will not be repeated here.

[0256] S1205. The terminal device sends the first information to the MME.

[0257] Accordingly, the MME receives this first information.

[0258] The first information indicates that the NR in the first PLMN is unavailable, and the first information also indicates the first duration for which the NR in the first PLMN is unavailable.

[0259] The specific implementation of this step can be found in step S1104 of the embodiment shown in Figure 11, and will not be repeated here.

[0260] S1206.MME sends the fourth message to LTE-RAN.

[0261] Accordingly, the LTE-RAN receives this fourth piece of information.

[0262] The fourth piece of information indicates that the NR in the first PLMN is unavailable.

[0263] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0264] S1207.LTE-RAN determines, based on the fourth information, whether to switch or redirect to the NR in the first PLMN.

[0265] The specific implementation of this step can be found in step S606 of the embodiment shown in Figure 6, and will not be repeated here.

[0266] When S1208.LTE-RAN receives the first information, it starts the second timer.

[0267] The duration of the second timer is the same as the first duration mentioned above.

[0268] The specific implementation of this step can be found in step S1107 of the embodiment shown in Figure 11, and will not be repeated here.

[0269] S1209. The second timer expires. If the terminal device is in the first PLMN, the LTE-RAN triggers a handover to the NR-RAN.

[0270] The specific implementation of this step can be referred to step S1108 of the embodiment shown in Figure 11, and will not be repeated here.

[0271] The following description uses the example of an unavailable NR in the first PLMN, where information indicating the unavailability of the NR in the first PLMN and the first duration are carried in the LTE access request:

[0272] Figure 13 shows a flowchart of another communication method provided in an embodiment of this application. Exemplarily, the method may include the following steps:

[0273] S1301. Whether the terminal device and the network both support the first feature.

[0274] The first characteristic indicates that the NR of the first PLMN should be enabled.

[0275] The specific implementation of this step can be referred to step S601 of the embodiment shown in Figure 6, and will not be repeated here.

[0276] S1302. The terminal device determines that the NR in the first PLMN is unavailable.

[0277] The specific implementation of this step can be referred to step S602 of the embodiment shown in Figure 6, and will not be repeated here.

[0278] S1303. The terminal device disables the NR in the first PLMN.

[0279] Alternatively, the terminal device can be configured to disable the NR in the first PLMN.

[0280] The specific implementation of this step can be found in step S603 of the embodiment shown in Figure 6, and will not be repeated here.

[0281] S1304. The terminal device sends an LTE access request to the MME.

[0282] Accordingly, the MME receives the LTE access request.

[0283] The LTE access request includes first information indicating that the NR in the first PLMN is unavailable, and the first information also indicates a first duration for which the NR in the first PLMN is unavailable.

[0284] The specific implementation of this step can be referred to step S804 of the embodiment shown in Figure 8 and step S1104 of the embodiment shown in Figure 11, and will not be repeated here.

[0285] S1305.MME sends the fourth message to LTE-RAN.

[0286] Accordingly, the LTE-RAN receives this fourth piece of information.

[0287] The fourth piece of information indicates that the NR in the first PLMN is unavailable.

[0288] The specific implementation of this step can be referred to step S605 of the embodiment shown in Figure 6, and will not be repeated here.

[0289] S1306.LTE-RAN determines, based on the fourth information, whether to switch or redirect to the NR in the first PLMN.

[0290] The specific implementation of this step can be found in step S606 of the embodiment shown in Figure 6, and will not be repeated here.

[0291] When S1307.LTE-RAN receives the first information, it starts the second timer.

[0292] The duration of the second timer is the same as the first duration mentioned above.

[0293] The specific implementation of this step can be found in step S1107 of the embodiment shown in Figure 11, and will not be repeated here.

[0294] S1308. The second timer expires. If the terminal device is in the first PLMN, the LTE-RAN triggers a handover to the NR-RAN.

[0295] The specific implementation of this step can be referred to step S1108 of the embodiment shown in Figure 11, and will not be repeated here.

[0296] In this application, the phrase "sending information to... (e.g., a terminal device)" or the related illustrations in the accompanying drawings can be understood as the destination of the information being the terminal device. This can include sending information directly or indirectly to the terminal device. Similarly, the phrase "receiving information from... (e.g., a terminal device)" or "receiving information from... (e.g., a terminal device)" or the related illustrations in the accompanying drawings can be understood as the source of the information being the terminal device. This can include receiving information directly or indirectly from the terminal device. Information may undergo necessary processing between the source and destination, such as format changes, but the destination can understand the valid information from the source. Similar expressions in this application can be interpreted similarly, and will not be elaborated further here.

[0297] It is understood that this application uses terminal devices and network devices (including access network devices and core network devices) as examples to illustrate the execution of the interaction, but this application does not limit the execution of the interaction. For example, the terminal device in the method provided by this application can also be a chip, chip system, or processor applied to the terminal device, or it can be a logical node, logical module, or software that can implement all or part of the terminal device; the network device in the method provided by this application can also be a chip, chip system, or processor applied to the network device, or it can be a logical node, logical module, or software that can implement all or part of the network device functions.

[0298] It is understood that, in order to achieve the functions in the above embodiments, the network device and terminal device include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the units and method steps of the various examples described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0299] Figures 14 and 15 are schematic diagrams of possible communication devices provided in embodiments of this application. These communication devices can be used to implement the functions of terminal devices or network devices in the above method embodiments, and thus can also achieve the beneficial effects of the above method embodiments. In the embodiments of this application, the communication device can be one of the terminal devices 120a-120j shown in Figure 1, or it can be the access network device 110a or 110b shown in Figure 1, or it can be a device in the core network 200, or it can be a module (such as a chip) applied to the terminal device, access network device, or core network device.

[0300] As shown in Figure 14, the communication device 1400 includes a processing unit 1410 and a transceiver unit 1420. The communication device 1400 is used to implement the functions of the terminal device or network device in the method embodiments shown in Figures 6-13 above.

[0301] When the communication device 1400 is used to implement the functions of a terminal device: the processing unit 1410 is used to implement at least one of steps S602 and S603 in the embodiment shown in FIG6, and the transceiver unit 1420 is used to implement at least one operation implemented by the terminal device in steps S601 and S604 in the embodiment shown in FIG6; or, the processing unit 1410 is used to implement at least one of steps S902 and S903 in the embodiment shown in FIG9, and the transceiver unit 1420 is used to implement at least one operation implemented by the terminal device in steps S901 and S904 in the embodiment shown in FIG9; or, the processing unit 1410 is used to implement at least one of steps S1102 and S1103 in the embodiment shown in FIG11, and the transceiver unit 1420 is used to implement at least one operation implemented by the terminal device in steps S1101 and S1104 in the embodiment shown in FIG11.

[0302] When the communication device 1400 is used to implement the functions of the core network device: the transceiver unit 1420 is used to implement at least one operation implemented by the access network device in steps S601, S604, and S605 in the embodiment shown in FIG6; or, the processing unit 1410 is used to implement step S907 in the embodiment shown in FIG9, and the transceiver unit 1420 is used to implement at least one operation implemented by the core network device in steps S901, S904, S905, and S908 in the embodiment shown in FIG9; or, the transceiver unit 1420 is used to implement at least one operation implemented by the core network device in steps S1101, S1104, and S1105 in the embodiment shown in FIG11.

[0303] When the communication device 1400 is used to implement the functions of an access network device: the processing unit 1410 is used to implement step S606 in the embodiment shown in FIG6, and the transceiver unit 1420 is used to implement the operation implemented by the access network device in step S605 in the embodiment shown in FIG6; or, the processing unit 1410 is used to implement at least one of steps S906 and S909 in the embodiment shown in FIG9, and the transceiver unit 1420 is used to implement at least one operation implemented by the access network device in steps S905 and S908 in the embodiment shown in FIG9; or, the processing unit 1410 is used to implement at least one of steps S1106 to S1108 in the embodiment shown in FIG11, and the transceiver unit 1420 is used to implement the operation implemented by the access network device in step S1105 in the embodiment shown in FIG11.

[0304] A more detailed description of the processing unit 1410 and the transceiver unit 1420 can be obtained directly from the relevant descriptions in the method embodiments shown in Figures 6-13, and will not be repeated here.

[0305] When the aforementioned communication device is a chip applied to a terminal device, the terminal device chip implements the functions of the terminal device in the above method embodiments. The terminal device chip receives information from other modules (such as an RF module or antenna) in the terminal device, the information being sent to the terminal device by the network device; or, the terminal device chip sends information to other modules (such as an RF module or antenna) in the terminal device, the information being sent to the network device by the terminal device.

[0306] When the aforementioned communication device is a chip applied to a network device, the network device chip implements the functions of the network device in the above method embodiments. The network device chip receives information from other modules (such as radio frequency modules or antennas) in the network device, which is information sent from the terminal device to the network device; or, the network device chip sends information to other modules (such as radio frequency modules or antennas) in the network device, which is information sent from the network device to the terminal device.

[0307] Furthermore, it should be noted that the aforementioned transceiver unit and / or processing unit can be implemented through virtual modules. For example, the processing unit can be implemented through software functional units or virtual devices, and the transceiver unit can be implemented through software functions or virtual devices. Alternatively, the processing unit or transceiver unit can also be implemented through physical devices. For example, if the device is implemented using a chip / chip circuit, the transceiver unit can be an input / output circuit and / or a communication interface, performing input operations (corresponding to the aforementioned receiving operation) and output operations (corresponding to the aforementioned sending operation); the processing unit is an integrated processor, microprocessor, or integrated circuit.

[0308] As shown in Figure 15, the communication device 1500 includes a processor 1510 and may also include an interface circuit 1520. The processor 1510 and the interface circuit 1520 are coupled to each other. It is understood that the interface circuit 1520 can be a transceiver or an input / output interface. Optionally, the communication device 1500 may also include a memory 1530 (shown as a dashed line in Figure 15) for storing instructions executed by the processor 1510, or storing input data required by the processor 1510 to execute instructions, or storing data generated after the processor 1510 executes instructions.

[0309] When the communication device 1500 is used to implement the functions of the terminal device: the processor 1510 is used to implement at least one of steps S602 and S603 in the embodiment shown in FIG6, and the interface circuit 1520 is used to implement at least one operation implemented by the terminal device in steps S601 and S604 in the embodiment shown in FIG6; or, the processor 1510 is used to implement at least one of steps S902 and S903 in the embodiment shown in FIG9, and the interface circuit 1520 is used to implement at least one operation implemented by the terminal device in steps S901 and S904 in the embodiment shown in FIG9; or, the processor 1510 is used to implement at least one of steps S1102 and S1103 in the embodiment shown in FIG11, and the interface circuit 1520 is used to implement at least one operation implemented by the terminal device in steps S1101 and S1104 in the embodiment shown in FIG11.

[0310] When the communication device 1500 is used to implement the functions of the core network device: the interface circuit 1520 is used to implement at least one operation implemented by the access network device in steps S601, S604, and S605 in the embodiment shown in FIG6; or, the processor 1510 is used to implement step S907 in the embodiment shown in FIG9, and the interface circuit 1520 is used to implement at least one operation implemented by the core network device in steps S901, S904, S905, and S908 in the embodiment shown in FIG9; or, the interface circuit 1520 is used to implement at least one operation implemented by the core network device in steps S1101, S1104, and S1105 in the embodiment shown in FIG11.

[0311] When the communication device 1500 is used to implement the functions of an access network device: the processor 1510 is used to implement step S606 in the embodiment shown in FIG6, and the interface circuit 1520 is used to implement the operation implemented by the access network device in step S605 in the embodiment shown in FIG6; or, the processor 1510 is used to implement at least one of steps S906 and S909 in the embodiment shown in FIG9, and the interface circuit 1520 is used to implement at least one operation implemented by the access network device in steps S905 and S908 in the embodiment shown in FIG9; or, the processor 1510 is used to implement at least one of steps S1106 to S1108 in the embodiment shown in FIG11, and the interface circuit 1520 is used to implement the operation implemented by the access network device in step S1105 in the embodiment shown in FIG11.

[0312] A more detailed description of the processor 1510 and interface circuit 1520 can be obtained directly from the relevant descriptions in the method embodiments shown in Figures 6-13, and will not be repeated here.

[0313] When the aforementioned communication device is a chip applied to a terminal device, the terminal device chip implements the functions of the terminal device in the above method embodiments. The terminal device chip receiving information from a base station can be understood as the information being first received by other modules (such as an RF module or antenna) in the terminal device, and then sent to the terminal device chip by these modules. The terminal device chip sending information to the base station can be understood as the information being first sent to other modules (such as an RF module or antenna) in the terminal device, and then sent to the base station by these modules.

[0314] When the aforementioned communication device is a chip used in a base station, the base station chip implements the functions of the base station in the above method embodiments. The base station chip receives information from the terminal device, which can be understood as the information being first received by other modules in the base station (such as an RF module or antenna), and then sent to the base station chip by these modules. The base station chip sends information to the terminal device, which can be understood as the information being sent down to other modules in the base station (such as an RF module or antenna), and then sent to the terminal device by these modules.

[0315] In this application, entity A sends information to entity B, either directly or indirectly through other entities. Similarly, entity B receives information from entity A, either directly or indirectly through other entities. Entities A and B can be RAN nodes or terminal devices, or modules within RAN nodes or terminal devices. Information transmission and reception can be between RAN nodes and terminal devices, such as between a base station and a terminal device; between two RAN nodes, such as between a CU and a DU; or between different modules within a single device, such as between a terminal device chip and other modules of the terminal device, or between a base station chip and other modules of the base station.

[0316] It is understood that in this application, "instruction" can include direct instruction, indirect instruction, explicit instruction, and implicit instruction. When describing a certain instruction information to indicate A, it can be understood that the instruction information carries A, directly indicates A, or indirectly indicates A. In this application, the information indicated by the instruction information is called the information to be instructed. In specific implementation, there are many ways to indicate the information to be instructed, such as, but not limited to, directly indicating the information to be instructed, such as the information to be instructed itself or its index, or indirectly indicating the information to be instructed by indicating other information, wherein there is an association between the other information and the information to be instructed. It is also possible to indicate only a part of the information to be instructed, while the other parts of the information to be instructed are known or agreed upon in advance. For example, the instruction of specific information can also be achieved by using the arrangement order of various information in advance (e.g., as specified by a protocol), thereby reducing the instruction overhead to a certain extent. The information to be instructed can be sent as a whole or divided into multiple sub-information to be sent separately, and the sending period and / or sending time of these sub-information can be the same or different. This application does not limit the specific sending method. The sending period and / or timing of these sub-information messages can be predefined, for example, according to a protocol, or configured by the transmitting device by sending configuration information to the receiving device.

[0317] It is understood that the processor in the embodiments of this application can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, field-programmable gate arrays, or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0318] The method steps in the embodiments of this application can be implemented in hardware or in software instructions executable by a processor. The software instructions can consist of corresponding software modules, which can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disks, portable hard disks, read-only optical discs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. The storage medium can also be a component of the processor. The processor and the storage medium can reside in an application-specific integrated circuit (ASIC). Alternatively, the ASIC can reside in a base station or terminal device. The processor and the storage medium can also exist as discrete components in the base station or terminal device.

[0319] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of this application are performed entirely or partially. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user equipment, or other programmable device. The computer program or 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 optical disc; or it can be a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both types of storage media.

[0320] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions between different embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0321] Depending on whether the specification uses "optional": In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates an "or" relationship between the preceding and following related objects; in the formulas of this application, the character " / " indicates a "division" relationship between the preceding and following related objects. "Including at least one of A, B, and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B, and C.

[0322] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method characterized by comprising: The method includes: It was determined that the first radio access technology (RAT) was unavailable in the first public terrestrial mobile network (PLMN). Send a first message indicating that the first RAT in the first PLMN is unavailable.

2. The method of claim 1, wherein, The method further includes: Set the first RAT in the first PLMN to be unavailable, or disable the first RAT in the first PLMN.

3. The method of claim 1 or 2, wherein, The first information includes the identifier of the first RAT.

4. The method of claim 3, wherein, The first information also includes the identifier of the first PLMN.

5. The method of any one of claims 1-4, wherein, The first information also indicates a first duration during which the first RAT in the first PLMN is unavailable.

6. The method of any one of claims 1-5, wherein, The first information is carried in the first request, which is used to request registration or access to the network.

7. The method of any one of claims 1-6, wherein, The method further includes: Whether the network negotiation supports the first feature, the first feature indicates to enable the first RAT of the first PLMN.

8. The method of any one of claims 1-7, wherein, When the terminal device moves to the second PLMN, the method further includes: Receive the second information and switch to the first RAT of the second PLMN according to the second information; or reselect to the first RAT of the second PLMN.

9. The method of claim 8, wherein, The second information indicates access to the second PLMN based on the first RAT.

10. A communication method characterized by comprising: The method includes: Receive first information from the terminal device, the first information indicating that the first radio access technology (RAT) in the first public terrestrial mobile network (PLMN) is unavailable; A fourth message is sent to the access network device, the fourth message indicating that the first RAT in the first PLMN is unavailable.

11. The method of claim 10, wherein, The first information includes the identifier of the first RAT.

12. The method of claim 11, wherein, The first information also includes the identifier of the first PLMN.

13. The method of any one of claims 10-12, wherein, The first information also indicates a first duration during which the first RAT in the first PLMN is unavailable.

14. The method of any one of claims 10-13, wherein, The fourth message also indicates a first duration during which the first RAT in the first PLMN is unavailable.

15. The method of claim 13 or 14, wherein, The method further includes: Upon receiving the first information, a first timer is started, and the duration of the first timer is the first duration. When the first timer expires, a fifth message is sent, which instructs the access network device to delete the information that the first RAT is unavailable in the first PLMN.

16. The method of any one of claims 10-15, wherein, The first information is carried in the first request, which is used to request registration or access to the network.

17. The method of any one of claims 10-16, wherein, The method further includes: Negotiate with the terminal device whether both support the first feature, the first feature indicating to enable the first RAT of the first PLMN.

18. A method of communication, comprising: The method includes: Receive a fourth message indicating that the first radio access technology (RAT) in the first public terrestrial mobile network (PLMN) is unavailable; Based on the fourth information, it is determined not to switch or redirect to the first RAT in the first PLMN.

19. The method of claim 18, wherein, The fourth piece of information includes the identifier of the first RAT.

20. The method of claim 19, wherein, The fourth piece of information also includes the identifier of the first PLMN.

21. The method of any one of claims 18-19, wherein, When the terminal device moves to the second PLMN, the method further includes: Based on the fourth information, a second information is sent, the second information indicating access to the second PLMN based on the first RAT; Receive third information, which is used to request access to the second PLMN based on the first RAT.

22. The method of any one of claims 18-21, wherein, The fourth information also indicates the first duration during which the first RAT is unavailable in the first PLMN; The method further includes: Upon receiving the fourth information, a second timer is started, the duration of which is the first duration; If the second timer times out and the terminal device is in the first PLMN, a sixth message is sent, indicating access to the first PLMN based on the first RAT.

23. A communications device, characterized by It includes modules for implementing the method as described in any one of claims 1 to 9, or modules for implementing the method as described in any one of claims 10 to 17, or modules for implementing the method as described in any one of claims 18 to 22.

24. A communications device, characterized by The device includes a processor and an interface circuit. The interface circuit is used to receive signals from other communication devices and transmit them to the processor or to send signals from the processor to other communication devices. The processor is used to implement the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 17, or the method as described in any one of claims 18 to 22, through logic circuits or executing code instructions.

25. A computer readable storage medium, characterized in that, The storage medium stores a computer program or instructions, which, when executed by a communication device, implement the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 17, or the method as described in any one of claims 18 to 22.

26. A computer program product, characterised in that, The computer program product includes the program instructions involved, which, when executed, implement the method as described in any one of claims 1 to 9, or the method as described in any one of claims 10 to 17, or the method as described in any one of claims 18 to 22.

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