Patent ID: 12238810

DESCRIPTION OF EMBODIMENTS

In embodiments of this application, to clearly describe the technical solutions in the embodiments of this application, words such as “first” and “second” are used to distinguish between same items or similar items whose functions are basically the same. A person skilled in the art may understand that the terms such as “first” and “second” do not constitute a limitation on a quantity or an execution sequence, and that the terms such as “first” and “second” do not indicate a definite difference. There is no chronological order or no size order between the technical features described by the “first” and the “second”.

In the embodiments of this application, the word such as “example” or “for example” is used to give an example, an illustration, or a description. Any embodiment or design scheme described as the word “example” or “for example” in the embodiments of this application should not be explained as being more preferred or having more advantages than another embodiment or design scheme. Exactly, use of the word “example”, “for example”, or the like is intended to present a relative concept in a specific manner for ease of understanding.

In the descriptions of this application, “I” represents an “or” relationship between associated objects unless otherwise specified. For example, A/B may represent A or B. The term “and/or” in this application indicates only an association relationship for describing associated objects and indicates that three relationships may exist. For example, A and/or B may indicate the following three cases: Only A exists, both A and B exist, and only B exists, where A and B may be singular or plural. In addition, unless otherwise specified, “a plurality of” in the descriptions of this application means two or more than two. “At least one item (piece) of the following” or a similar expression thereof means any combination of these items, including a singular item (piece) or any combination of plural items (pieces). For example, at least one of a, b, or c may indicate: a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural.

In the embodiments of this application, “at least one” may also be described as “one or more”, and “a plurality of” may be “two, three, four, or more”. These are not limited in this application.

A network architecture and a scenario described in the embodiments of this application are intended to describe the technical solutions in the embodiments of this application more clearly, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. A person of ordinary skill in the art may know that: With evolution of the network architecture and the emergence of new service scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

A method provided in the embodiments of this application may be applied to any communications system supporting V2X service data transmission. The communications system may be a 3rd generation partnership project (3GPP) communications system, for example, a long term evolution (LTE) system, a 5th generation (5G) mobile communications system, or a new radio (NR) system, or may be a non-3GPP communications system. This is not limited.

As shown inFIG.1, an architectural diagram of a communications system is provided. The communications system may include a terminal, an access network device, a core network device, a data network (DN), and the like. Referring toFIG.1, the core network device may include an AMF, a policy control function (PCF), unified data management (UDM), a session management function (SMF), and a user plane function (UPF). The following describes an apparatus in this application with reference toFIG.1.

The terminal may be referred to as user equipment (UE) or a terminal device (terminal). The terminal may support V2X communication, which is, for example, receiving or sending a V2X message. In this case, the terminal may also be referred to as a V2X terminal. The V2X message may include but is not limited to a vehicle to vehicle (V2V) message, a vehicle to person (V2P) message, a vehicle to network (V2N) message, vehicle to infrastructure (V2I) information, an anti-collision message between vehicles, an entertainment application message, a navigation message exchanged between vehicles, and the like. The terminal shown inFIG.1may include but is not limited to a vehicle-mounted terminal, a mobile phone, a tablet computer or a computer having a wireless transceiver function, a smart gas station, an intelligent traffic light, and the like.

In the embodiments of this application, the terminal may transmit the V2X message through communications interfaces of different types. A communications interface may include a PC5 interface and/or a Uu interface.

The access network device is responsible for radio resource management, uplink and downlink data classification, and QoS application, completes signaling processing with a control plane network element, and completes functions such as data forwarding with a user plane network element. For example, the access network device may be a base station, a broadband network gateway (BNG), an aggregation switch, a non-3GPP access device, or the like. The base station may be various types of base stations, for example, a macro base station, a micro base station (which is also referred to as a small cell), a relay node, and an access point. This is not limited in the embodiments of this application. A device through which the terminal accesses the core network is referred to as the access network device in this specification, and details are not described herein. For example, the access network device may be an evolved universal terrestrial radio access network (E-UTRAN) device in a 4G network, a next-generation radio access network (NG-RAN) device in a 5G network, or the like.

Main functions of the AMF include a termination point of a radio access network control plane, a termination point of non-access signaling, mobility management, lawful interception, access authorization/authentication, and the like.

The SMF is used for session management, internet protocol (IP) address allocation and management of the terminal, a function of selecting a manageable user plane, a termination point of a policy control and charging function interface, downlink data notification, and the like.

The UPF is used for packet routing and forwarding, quality of service (QoS) processing of user plane data, and the like. The DN is a network, for example, an Internet network, used to transmit data.

The PCF is configured to provide a parameter related to a UE policy for the terminal, a parameter related to an access and mobility (AM) policy for the AMF, and a parameter related to a session management (SM) policy for the SMF. In a V2X scenario, the PCF provides information such as V2X-related authentication and policy parameters for the terminal and the access network device.

The UDM is configured to manage subscription information, provide the subscription information for a related network element, and the like.

It should be noted that a network consisting of operator network elements other than a RAN may become a core network. In the 4G network, the core network includes network elements such as an MME, an S-GW, a P-GW, and an HSS. In the 5G network, the core network includes network elements such as the AMF, SMF, UPF, UDM, and PCF.

A Uu interface inFIG.1is a wireless connection interface between the terminal and the access network device. An N2 interface is a reference point between the access network device and the core network device (AMF), is configured to send a NAS message, and may be further configured to transmit related information for configuring an access network. Therefore, a communication connection between the access network device and the core network device may be referred to as an N2 connection. A PC5 interface is a reference point for user plane ProSe direct communication between terminals for a V2X service.

It should be noted that a network architecture that the embodiments of this application use is not limited to the network architecture shown inFIG.1. In addition, the network architecture shown inFIG.1is merely an example architectural diagram, and a quantity of network elements included in the communications system and names of the network elements are not limited. For example, in addition to the network functional entities shown inFIG.1, the network shown inFIG.1may further include another functional entity. For another example, names of the network elements, interfaces between the network elements, and the protocol layers in the architecture shown inFIG.1are merely examples, and may be other names during specific implementation. This is not limited in the embodiments of this application.

The solutions provided in the embodiments of this application may be applied to a process in which a terminal registers with a network and an interaction process between network elements after the registration is completed in a wireless communications system. Before the specific solutions of this application are described, the process in which the terminal registers with the network and the interaction process between the network elements after the registration in the wireless communications system are first briefly described herein.

In the wireless communications system, the terminal may send a registration request to the network in a plurality of scenarios such as initial network access, periodic registration, or registration caused by mobility. This is not limited in the embodiments of this application. A 5G communications system is used as an example to describe a registration procedure of the terminal and the interaction process between the network elements after the registration is completed. As shown inFIG.2, the process may include the following steps.

S201. The terminal sends a registration request message to an AMF.

The registration request message is a NAS message, and the registration request message carries an identifier of the terminal. The identifier of the terminal is used to uniquely indicate the terminal. Content of information about the identifier is not limited in this application.

Further, the registration request message may further include capability information of the terminal, and the capability information is used to indicate a capability that the terminal has.

The registration request message is sent to the AMF via a RAN.

S202. The AMF obtains subscription information of the terminal from UDM based on the identifier of the terminal.

In S202, that a core network device obtains the subscription information of the terminal from the UDM based on the identifier of the terminal may be implemented as follows: The core network device obtains the subscription information of the terminal from the UDM based on the identifier of the terminal and other information of the terminal. The foregoing other information may be the capability information of the terminal or other information. This is not limited in this embodiment of this application.

S203. The AMF selects a PCF, and establishes an AMF-PCF association relationship.

In S203, the core network device may select the corresponding PCF based on the subscription information of the terminal. In S203, the core network device may further send policy-related request information of the terminal to the PCF, so that the PCF updates a policy of the terminal. For example, the core network device may add, to a policy container of the terminal, a policy that has been learned by the terminal, and send the policy container to the PCF. It should be noted that for specific implementation of S203, refer to the standard 3GPP TS 23.502 and the standard 3GPP TS 23.503. Details are not described in this embodiment of this application.

S204. The core network device sends a registration accept message to the terminal.

The registration accept message is a NAS message. The registration accept message sent by the core network device is sent to the access network device by using a terminal context setup request borne on a next generation application protocol (NGAP) interface. The access network device sends the registration accept request to the terminal by using an RRC connection reconfiguration message.

In this case, the terminal completes registration, and establishes an N2 connection between the AMF and the RAN, an RRC connection between the RAN and the terminal, and an N1 connection between the AMF and the terminal. The RAN stores a context of the terminal, and the terminal enters a connected mode.

As shown inFIG.2, after completion of registration for the terminal, the process of interaction between the network elements includes the following steps.

S205. The AMF determines whether the terminal has a data or signaling transmission requirement.

In S205, if the AMF determines that the terminal has the data or signaling transmission requirement, the AMF maintains the N2 connection between the AMF and the RAN and the N1 connection between the RAN and the terminal, to perform a subsequent communication process. If the AMF determines that the terminal has no data or signaling transmission requirement, S206is performed.

In S205, how the AMF determines whether the terminal has the data or signaling transmission requirement may be configured based on an actual requirement. This is not limited in this embodiment of this application.

For example, when the terminal still has to-be-processed uplink signaling after the registration is completed, the registration request of the terminal carries an indication (for example, a follow-on request) indicating that a NAS message further needs to be sent. In this case, the AMF may determine that the terminal has the signaling transmission requirement. The NAS message sent by the terminal after the registration may include a NAS message used to establish a PDU session or activate a PDU session.

For another example, if the terminal has registered with the network before, and has established a corresponding PDU session, in registration caused by periodic registration or mobility, the terminal initiates the registration request message in S201in an idle mode, and the registration request message includes an information element of a session to be activated (IE of a PDU session to-be-activated). In this case, the AMF may determine a data transmission requirement of the terminal.

S206. The AMF starts a timer used to release the N2 connection.

The timer used to release the N2 connection may be a T3540 timer, and duration of the T3540 timer may be 10 seconds. After the T3540 timer expires, S206is performed.

S206. The AMF sends, to the RAN, an NGAP message used to release the N2 connection.

S207. The RAN receives the NGAP message used to release the N2 connection.

S208. The RAN starts a timer used to release the N2 connection.

The timer used to release the N2 connection may be an inactivity timer. If the RAN receives the data transmission requirement of the terminal in a running process of the inactivity timer, the RAN refuses to release the N2 connection. If the RAN does not receive the data transmission requirement of the terminal after the inactivity timer expires, S209is performed to release the N2 connection.

S209. Release the N2 connection.

A specific process of releasing the N2 connection may include: The RAN deletes the stored context of the terminal. The RAN sends, to the terminal, a message used to release the N1 connection. The RAN responds, to the AMF, the NGAP message used to release the N2 connection. After S208is performed, both the N2 connection between the AMF and the RAN and the RRC connection between the RAN and the terminal are released. The RAN stores the context of the terminal, and the terminal enters the idle mode.

The following describes implementations of the embodiments of this application in detail with reference to the accompanying drawings. It should be noted that in the following embodiments of this application, names of messages between network elements, names of parameters in messages, or the like are merely examples, and may be other names during specific implementation. This is not limited in the embodiments of this application.

FIG.3is a schematic composition diagram of a communications apparatus30according to an embodiment of this application. As shown inFIG.3, the communications apparatus30may include at least one processor31, a memory32, a communications interface33, and a communications bus34. The following describes each composition component of the communications apparatus30in detail with reference toFIG.3.

The processor31may be one processor, or may be a collective name of a plurality of processing elements. For example, the processor31may be a central processing unit (CPU) or an application-specific integrated circuit (ASIC), or may be one or more integrated circuits, for example, one or more microprocessors (DSP) or one or more field programmable gate arrays (FPGA), configured to implement the embodiments of this application.

The processor31may perform various functions of the communications apparatus30by running or executing a software program stored in the memory32and invoking data stored in the memory32. In specific implementation, in an embodiment, the processor31may include one or more CPUs, for example, a CPU0and a CPU1shown inFIG.3.

In specific implementation, in an embodiment, the communications apparatus30may include a plurality of processors, for example, the processor31and a processor35shown inFIG.3. Each of the processors may be a single-core processor (single-CPU) or may be a multi-core processor (multi-CPU). The processor herein may refer to one or more devices, circuits, and/or processing cores configured to process data (for example, a computer program instruction).

The memory32may be a read-only memory (ROM) or another type of static storage device that can store static information and instructions, or a random access memory (RAM) or another type of dynamic storage device that can store information and instructions, or may be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or another compact disc storage, an optical disc storage (including a compact disc, a laser disc, an optical disc, a digital versatile disc, a Blu-ray disc, and the like), a magnetic disk storage medium or another magnetic storage device, or any other medium that can be configured to carry or store expected program code in a form of an instruction or a data structure and that can be accessed by a computer. However, the memory32is not limited thereto. The memory32may exist independently, and is connected to the processor31through the communications bus34. Alternatively, the memory32may be integrated with the processor31. The memory32is configured to store a software program for executing the solutions of this application, and the processor31controls execution.

The communications interface33is configured to communicate with another device or a communications network, such as the Ethernet, a radio access network (RAN), or a wireless local area network (WLAN) through any apparatus such as a transceiver. The communications interface33may include a receiving unit and a sending unit.

The communications bus34may be an industry standard architecture (ISA) bus, a peripheral component interconnect (PCI) bus, an extended industry standard architecture (EISA) bus, or the like. The bus may be classified into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is used to represent the bus inFIG.3, but this does not mean that there is only one bus or only one type of bus.

It should be noted that the components shown inFIG.3do not constitute a limitation on the communications apparatus. In addition to the components shown inFIG.3, the communications apparatus may include more or fewer components than those shown in the figure, or some components may be combined, or different component arrangements may be used.

In a possible implementation, the processor31runs or executes the software program and/or the module stored in the memory32, and invokes the data stored in the memory32, to perform the following functions:

obtaining indication information, where the indication information is used to indicate to maintain or skip releasing a signaling connection between a core network device and a V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing a communication connection of a V2X terminal between a core network device and an access network device of the V2X terminal after completion of registration for the V2X terminal; and maintaining or skipping releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the obtained indication information.

In another possible implementation, the processor31runs or executes the software program and/or the module stored in the memory32, and invokes the data stored in the memory32, to perform the following functions:

when a V2X terminal in which the communications apparatus30is located transmits V2X service data through PC5 interface communication in a base station scheduling mode, or when a V2X terminal in which the communications apparatus30is located transmits V2X service data by using a spectrum controlled by a current camped cell, sending indication information to a core network device, where the indication information is used to indicate to maintain or skip releasing a signaling connection between a core network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing a communication connection of the V2X terminal between a core network device and an access network device of the V2X terminal after completion of registration for the V2X terminal; and sending a resource request message to the access network device, where the resource request message is used to request a PC5 interface communication resource from the access network device, and the PC5 interface communication resource is used to transmit the V2X service data.

In yet another possible implementation, the processor31runs or executes the software program and/or the module stored in the memory32, and invokes the data stored in the memory32, to perform the following functions:

receiving a resource request message from a V2X terminal, where the resource request message is used to request to allocate a PC5 interface communication resource to the V2X terminal; and sending indication information to a core network device based on the resource request message, where the indication information is used to indicate to maintain or skip releasing a signaling connection between the core network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing a communication connection of the V2X terminal between the core network device and an access network device of the V2X terminal after completion of registration for the V2X terminal.

According to one aspect, an embodiment of this application provides a communications method, applied to an interaction process between a V2X terminal, an access network device, and a core network device.FIG.4is a flowchart of a communications method according to an embodiment of this application. As shown inFIG.4, the method may include the following steps.

S401. When the V2X terminal transmits V2X service data through PC5 interface communication in a base station scheduling mode, or when the V2X terminal transmits V2X service data by using a spectrum controlled by a current camped cell, the V2X terminal sends indication information to the core network device.

That the V2X service data is transmitted through the PC5 interface communication in the base station scheduling mode, or the V2X service data is transmitted by using the spectrum controlled by the current camped-on cell may be referred to as mode1PC5 interface communication. An essence of the mode1PC5 interface communication may be as follows: The access network device allocates a resource used to transmit the V2X service data, where the resource may be used for direct communication between a transmitting end and a receiving end, and the access network device does not need to forward the V2X service data.

It should be understood that in actual application, S401may also be replaced with the following: When the V2X terminal is in a scenario in which service data does not need to be forwarded and transmitted by the access network device but the access network device needs to allocate a resource for transmitting the V2X service data, the V2X terminal sends indication information to the core network device.

For example, in S401, the V2X terminal may determine, based on a policy configured in the V2X terminal and application layer data generated based on an operation of a user in a V2X application, to transmit the V2X service data through the PC5 interface communication in the base station scheduling mode, or to transmit the V2X service data by using the spectrum controlled by the current camped cell, where the application layer data may be the V2X service data.

Certainly, in actual application, a manner of transmitting the V2X service data may be configured and determined based on an actual requirement. This is not limited in this embodiment of this application.

The indication information may be used to indicate to maintain or skip releasing a signaling connection between the core network device and the V2X terminal after completion of registration for the V2X terminal. Alternatively, the indication information may be used to indicate to maintain or skip releasing a communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal after completion of registration for the V2X terminal, and the communication connection may be an N2 connection.

For example, in wireless communication, the terminal initiates registration to a network, and establishes, in a registration procedure, the signaling connection (for example, an N1 connection in 5G) between the core network device and the terminal, the communication connection (for example, the N2 connection in 5G) of the terminal between the core network device and the access network device of the terminal, and a connection (for example, an RRC connection in 5G) between the terminal and the access network device, so that the terminal enters a connected mode. After completion of registration for the terminal, if the core network device determines that the terminal has no data or signaling transmission requirement, the core network device sends a connection release request message to the access network device, to release the signaling connection between the core network device and the terminal, the communication connection of the terminal between the core network device and the access network device of the terminal, and the connection between the terminal and the access network device. The access network device deletes an internally stored context of the terminal. In this case, the terminal enters an idle mode.

It can be learned that, releasing the signaling connection between the core network device and the terminal, releasing the communication connection of the terminal between the core network device and the access network device of the terminal, releasing the connection between the terminal and the access network device, deleting the internally stored context of the terminal by the access network device, and entering the idle mode by the terminal are equivalent concepts, and can be replaced with each other.

In other words, maintaining or skipping releasing the signaling connection between the core network device and the terminal, maintaining or skipping releasing the communication connection of the terminal between the core network device and the access network device of the terminal, maintaining or skipping releasing the connection between the terminal and the access network device, reserving the internally stored context of the terminal by the access network device, and maintaining the connected mode by the terminal are equivalent concepts, and can be replaced with each other.

Therefore, the indication information described in this application is used to indicate to maintain or skip releasing the signaling connection between the core network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal after completion of registration for the V2X terminal. In addition, the indication information may be further used to indicate to maintain or skip releasing the connection between the access network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information may be further used to indicate the access network device to reserve the internally stored context of the terminal after completion of registration for the V2X terminal, or the indication information may be further used to indicate the V2X terminal to maintain the connected mode after completion of registration for the V2X terminal.

It should be noted that specific content of the indication information may be configured based on an actual requirement. This is not limited in this embodiment of this application.

For example, this embodiment of this application provides the following two possible implementations of the indication information.

Manner 1: The indication information may be an implicit indication.

For example, the indication information may include one or more of the following: a type of the V2X terminal, a first indication, and capability information used to indicate that the V2X terminal supports the PC5 interface communication.

The first indication is used to indicate that there is to-be-processed uplink signaling in the V2X terminal. That there is the to-be-processed uplink signaling may be replaced with a case in which there is an uplink non-access stratum (NAS) message other than a to-be-processed first service request, where the first service request is used to activate a user plane resource; or there is a to-be-processed second service request, where the second service request is used not to activate a user plane resource.

For example, the first indication may be an identifier of a follow-on request.

Manner 2: The indication information is an explicit indication.

For example, the indication information may be requesting to maintain or skip releasing the signaling connection between the core network device and the terminal, or requesting to maintain or skip releasing the communication connection of the terminal between the core network device and the access network device of the terminal, or requesting to maintain or skip releasing the connection between the terminal and the access network device, or requesting the access network device to reserve the internally stored context of the terminal, or requesting the terminal to maintain an explicit information element in the connected mode.

In S401, that the V2X terminal sends indication information to the core network device may be implemented in but is not limited to the following two manners.

Implementation A: The V2X terminal sends a registration request message to the core network device, where the registration request message carries the indication information.

The registration request message carries the indication information based on the registration request message in S201.

Implementation B: The V2X terminal sends independent indication information to the core network device.

In Implementation B, an execution occasion of S401may be selected based on an actual requirement. This is not limited in this embodiment of this application. For example, S401may be performed in a registration procedure of the V2X terminal, or may be performed after completion of registration for the V2X terminal.

It should be noted that the V2X terminal sends indication information to the core network device in S401is performed by using the access network device. Processing logic of the access network device in this process is not described in detail in this application.

S402. The core network device obtains the indication information.

A function of the indication information has been described in detail in S401, and details are not described herein again.

The indication information obtained by the core network device in S402may include one or more of the following: the type of the V2X terminal, the first indication, and the capability information used to indicate that the V2X terminal supports the PC5 interface communication. Alternatively, the indication information obtained by the core network device in S402may include one or more of the following: the type of the V2X terminal, the explicit indication in the manner 2 in S401, and the capability information used to indicate that the V2X terminal supports the PC5 interface communication.

In a possible implementation, the indication information obtained by the core network device in S402is the indication information sent by the V2X terminal in S401. In this implementation, the core network device directly receives the indication information from the V2X terminal in S402.

Corresponding to the implementation A and the implementation B in S401, that the core network device receives the indication information from the V2X terminal in S402may be implemented as follows: The core network device receives the registration request message from the V2X terminal, where the registration request message carries the indication information. Alternatively, the core network device receives the independent indication information sent by the V2X terminal.

In another possible implementation, the type of the V2X terminal and the capability information used to indicate that the V2X terminal supports the PC5 interface communication that are in the indication information obtained by the core network device in S402are content in subscription information of the V2X terminal. In this implementation, that the core network device obtains the indication information in S402may be implemented as follows: The core network device receives the indication information from the V2X terminal, and requests the subscription information of the V2X terminal from a subscription information management network element, to obtain the type of the V2X terminal and/or the capability information used to indicate that the V2X terminal supports the PC5 interface communication that are/is in the indication information.

S403. The core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information.

In a possible implementation, that the core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information in S403may be implemented as follows: The core network device skips sending the connection release request message to the access network device based on the indication information after completion of registration for the V2X terminal (that is, after the core network device sends a registration accept message to the V2X terminal).

The connection release request message is used to release the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal. For example, the connection release request message may be an N2 connection release request in a 5G system.

It should be noted that step S403may be replaced with the following: The core network device skips sending the connection release request message to the access network device based on the indication information. The core network device skips sending the connection release request message to the access network device based on the indication information after completion of registration for the V2X terminal (that is, after the core network device sends the registration accept message to the V2X terminal).

In another possible implementation, that the core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information in S403may be implemented as follows: The core network device skips starting, based on the indication information after completion of registration for the V2X terminal (that is, after the core network device sends a registration accept message to the V2X terminal), a timer for sending the connection release request message to the access network device.

It should be noted that step S403may be replaced with the following: The core network device skips starting, based on the indication information, a timer for sending the connection release request message to the access network device. The core network device skips starting, based on the indication information after completion of registration for the V2X terminal (that is, after the core network device sends a registration accept message to the V2X terminal), the timer for sending the connection release request message to the access network device.

In the foregoing process of S401to S403, the access network device reserves the context of the V2X terminal, so that the V2X terminal maintains the connected mode, and the V2X terminal can perform the PC5 interface communication in a process of S404to S406.

S404. The V2X terminal sends a resource request message to the access network device of the V2X terminal.

The resource request message is used to request a PC5 interface communication resource from the access network device, and the PC5 interface communication resource is used to transmit the V2X service data.

S405. The access network device receives the resource request message from the V2X terminal.

S406. The access network device allocates a resource to the V2X terminal based on the resource request message and the context that is of the V2X terminal.

According to the communications method provided in this application, the core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information provided by the V2X terminal. In this way, the context of the V2X terminal that is stored in the access network device in a registration phase of the V2X terminal is reserved, so as to support the access network device in allocating a PC5 interface resource to the V2X terminal based on the context of the V2X terminal, thereby ensuring that the V2X terminal implements the PC5 interface communication.

Optionally, if the V2X terminal adds the indication information to the registration request message for sending in S401, as shown inFIG.4, the communications method provided in this embodiment of this application may further include S407after S402and before S403, to complete a registration procedure of the V2X terminal.

S407. The core network device sends the registration accept message to the V2X terminal.

In a possible implementation, for S407, refer to specific implementation of S204. Details are not described herein again.

In another possible implementation, S407is implemented as S407ato S407c.

S407a. The core network device sends an NGAP message to the access network device.

The NGAP message includes a registration accept message and a second indication. The second indication is used to indicate the access network device to maintain or skip releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal.

S407b. The access network device sets first duration based on the second indication.

The first duration is duration in which when it is detected, after the second indication is received, that the V2X terminal has no data to transmit, the communication connection that is of the V2X terminal and that is between the core network device and the access network device of the V2X terminal is released, and the first duration is less than second duration. The second duration is duration that is set in the access network device and in which when it is detected that the V2X terminal has no data to transmit, the communication connection that is of the V2X terminal and that is between the core network device and the access network device of the V2X terminal is released. For example, the second duration is duration of an inactivity timer timer.

If the first duration expires, and the V2X terminal has no data to transmit, the access network device actively initiates release of the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal.

S407c. The access network device sends an RRC message to the V2X terminal, where the RRC message carries the registration accept message.

Optionally, if the indication information sent by the V2X terminal in S401includes the first indication, as shown inFIG.4, the communications method provided in this embodiment of this application may further include S408and S409.

S408. After receiving the registration accept message, the V2X terminal sends a NAS message to the core network device.

The NAS message sent by the V2X terminal in S408includes a service request message, and the service request message requesting not to activate a user plane resource.

For example, the service request message requesting not to activate the user plane resource is used to maintain the V2X terminal in the connected mode, or is used to maintain the N2 connection, or is used for not releasing the N2 connection. For example, the service request message requesting not to activate the user plane resource does not carry an information element of a PDU session to be activated. That is, UE does not further activate the user plane resource.

S409. The core network device receives the NAS message.

In S409, the core network device performs “Service Request procedures” in the standard 3GPP TS 23.502. A process is the same as a process in which the V2X terminal switches from the idle mode to the connected mode. Details are not described herein again.

According to another aspect, an embodiment of this application provides another communications method that may be applied to an interaction process of a V2X terminal, an access network device, and a core network device after completion of registration for the V2X terminal in the registration procedure shown inFIG.2.FIG.5is a flowchart of a communications method according to an embodiment of this application. As shown inFIG.5, the method may include the following steps.

S501. The V2X terminal sends a resource request message to the access network device of the V2X terminal.

The resource request message is used to request a PC5 interface communication resource from the access network device, and the PC5 interface communication resource is used to transmit V2X service data.

S502. The access network device receives the resource request message from the V2X terminal.

If the access network device receives the resource request message from the V2X terminal in S502, it indicates that the V2X terminal is performing mode1PC5 interface communication.

S503. The access network device sends indication information to the core network device based on the resource request message.

The indication information may be used to indicate to maintain or skip releasing a signaling connection between the core network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing a communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal after completion of registration for the V2X terminal.

As described above, the indication information described in this application is used to indicate to maintain or skip releasing the signaling connection between the core network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal after completion of registration for the V2X terminal. In addition, the indication information may be further used to indicate to maintain or skip releasing a connection between the access network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information may be further used to indicate the access network device to reserve an internally stored context of the terminal after completion of registration for the V2X terminal, or the indication information may be further used to indicate the V2X terminal to maintain a connected mode after completion of registration for the V2X terminal.

It should be noted that specific content of the indication information may be configured based on an actual requirement. This is not limited in this embodiment of this application.

For example, this embodiment of this application provides the following two possible implementations of the indication information.

Implementation a: The indication information is an explicit indication.

For example, the indication information may be requesting to maintain or skip releasing the signaling connection between the core network device and the terminal, or requesting to maintain or skip releasing the communication connection of the terminal between the core network device and the access network device of the terminal, or requesting to maintain or skip releasing the connection between the terminal and the access network device, or requesting the access network device to reserve the internally stored context of the terminal, or requesting the terminal to maintain an explicit information element in the connected mode.

Implementation b: The indication information may be an implicit indication.

For example, the indication information may include: information used to indicate that the V2X terminal is performing PC5 interface communication, or capability information used to indicate that the access network device supports PC5 interface communication.

For example, the indication information may include a reject message of a connection release request message. The connection release request message is used to release the communication connection of the V2X terminal between the core network device and the access network device.

For example, the connection release request message may be an N2 connection release message in a 5G system.

Further, when the indication information includes the reject message of the connection release request message, as shown inFIG.5, before S503, the communications method provided in this embodiment of this application may further include S503aand S503b.

S503a. The core network device sends the connection release request message to the access network device.

It should be noted that for specific implementation of S503a, refer to S206and S207. Details are not described herein again.

S503b. The access network device receives the connection release request message from the core network device.

Further, when the indication information includes the reject message of the connection release request message, S503may be implemented as follows: The access network device sends the reject message of the connection release request message to the core network device based on the resource request message and the connection release request message.

In a possible implementation, that the access network device sends the reject message to the core network device based on the resource request message and the connection release request message may be implemented as follows: The access network device starts a timer when receiving the resource request message. If the timer does not expire when the access network device receives the connection release request message, the access network device sends the reject message of the connection release request message to the core network device.

S504. The core network device obtains the indication information.

In S504, that the core network device obtains the indication information may be implemented as follows: The core network device receives the indication information from the access network device.

It should be noted that the indication information obtained by the core network device in S504is the indication information sent by the access network device in S503. Details are not described herein again.

S505. The core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information.

It should be noted that, for specific implementation of S505, refer to the specific implementation of S403. Details are not described herein again.

S506. The access network device allocates a resource to the V2X terminal based on the context of the V2X terminal.

According to the communications method provided in this application, when the access network device receives the resource request message from the V2X terminal, the access network device determines that the V2X terminal has a PC5 interface communication requirement that the access network device needs to allocate the resource, and the access network device sends the indication information to the core network device, so that the core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information. In this way, the context of the V2X terminal that is stored in the access network device in a registration phase of the V2X terminal is reserved, so as to support the access network device in allocating a PC5 interface resource to the V2X terminal based on the context of the V2X terminal, thereby ensuring that the V2X terminal implements the PC5 interface communication.

According to yet another aspect, an embodiment of this application provides yet another communications method, applied to an interaction process between a V2X terminal, an access network device, and a core network device.FIG.6is a flowchart of a communications method according to an embodiment of this application. As shown inFIG.6, the method may include the following steps.

S601. The core network device obtains indication information.

The indication information may be used to indicate to maintain or skip releasing a signaling connection between the core network device and the V2X terminal after completion of registration for the V2X terminal, or the indication information is used to indicate to maintain or skip releasing a communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal after completion of registration for the V2X terminal.

It should be noted that a function of the indication information has been described in detail in S401, and details are not described herein again.

It should be noted that specific content of the indication information may be configured based on an actual requirement. This is not limited in this embodiment of this application.

For example, this embodiment of this application provides the following two possible implementations of the indication information.

In a possible implementation, the indication information includes one or more of the following: a type of the V2X terminal and capability information indicating that the V2X terminal supports PC5 interface communication. S601may be implemented as follows: The core network device obtains the indication information from subscription information of the V2X terminal.

In another possible implementation, the indication information may include capability information used to indicate that the access network device supports PC5 interface communication. S601may be implemented as follows: When performing device-level interaction with the access network device, the core network device receives the indication information from the access network device.

In yet another possible implementation, the indication information includes one or more of the following: a type of the V2X terminal, capability information indicating that the V2X terminal supports PC5 interface communication, and capability information used to indicate that the access network device supports PC5 interface communication.

S602. The core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information.

For specific implementation of S602, refer to the specific implementation of S403. Details are not described herein again.

According to the communications method provided in this application, the core network device maintains or skips releasing the communication connection of the V2X terminal between the core network device and the access network device of the V2X terminal based on the indication information. In this way, a context of the V2X terminal that is stored in the access network device in a registration phase of the V2X terminal is reserved, so as to support the access network device in allocating a PC5 interface resource to the V2X terminal based on the context of the V2X terminal, thereby ensuring that the V2X terminal implements the PC5 interface communication.

According to yet another aspect, an embodiment of this application provides yet another communications method, applied to an interaction process between a V2X terminal, an access network device, and a core network device.FIG.6ais a flowchart of a communications method according to an embodiment of this application. As shown inFIG.6a, the method may include the following steps.

S701. The core network device obtains capability information used to indicate that the V2X terminal supports PC5 interface communication.

The core network device may be an AMF.

In a possible implementation, the core network device may receive the capability information from the V2X terminal in S701.

For example, the capability information may be an implementation of indication information in the foregoing embodiments. For a manner in which the V2X terminal sends the capability information, refer to the description in S401. Details are not described herein again.

In a possible implementation, the capability information may be carried in a registration request message.

For example, the registration request message carries the capability information based on the registration request message in S201.

S702. The core network device maintains or skips releasing a signaling connection between the V2X terminal and the core network device based on the capability information after completion of registration for the V2X terminal.

In a possible implementation, that the core network device maintains or skips releasing a signaling connection between the V2X terminal and the core network device based on the capability information after completion of registration for the V2X terminal in S702may be implemented as follows: The core network device skips sending a connection release request message to the access network device based on the capability information after completion of registration for the V2X terminal.

The connection release request message is used to release the signaling connection between the V2X terminal and the core network device. For example, the connection release request message may be an N2 connection release request in a 5G system.

In another possible implementation, that the core network device maintains or skips releasing a signaling connection between the V2X terminal and the core network device based on the capability information after completion of registration for the V2X terminal in S702may be implemented as follows: The core network device maintains or skips releasing the signaling connection between the V2X terminal and the core network device based on subscription information of the V2X terminal and the capability information after completion of registration for the V2X terminal.

The core network device may obtain the subscription information of the V2X terminal from UDM. The subscription information may include service information, authorization information, or the like to which the V2X terminal subscribes.

For example, in S702, the core network device may obtain the subscription information of the V2X terminal from the UDM, and determine, based on the subscription information of the V2X terminal and the capability information, that the V2X terminal is authorized to perform V2X communication on a PC5 interface. The core network device maintains or skips releasing the signaling connection between the V2X terminal and the core network device after completion of registration for the V2X terminal.

It should be noted that, for implementation of S702, refer to specific implementation of S403. Details are not described herein again.

According to the communications method provided in this application, the core network device maintains or skips releasing, based on the capability information indicating that the V2X terminal supports the PC5 interface communication, the signaling connection between the V2X terminal and the core network device after completion of registration for the V2X terminal. In this way, a context of the V2X terminal that is stored in the access network device in a registration phase of the V2X terminal is reserved, so as to support the access network device in allocating a PC5 interface resource to the V2X terminal based on the context of the V2X terminal, thereby ensuring that the V2X terminal implements the PC5 interface communication.

In the foregoing embodiments provided in this application, the method provided in the embodiments of this application is separately described from perspectives of the core network device, the access network device, and the V2X terminal. To implement the functions in the methods provided in the embodiments of this application, the core network device, the access network device, and the V2X terminal may include a hardware structure and/or a software module, and implement the functions in a form of a hardware structure, a software module, or a combination of a hardware structure and a software module. Whether a function of the functions is performed by using the hardware structure, the software module, or the combination of the hardware structure and the software module depends on a specific application and a design constraint of the technical solutions.

Division into modules in the embodiments of this application is an example, is merely logical function division, and may be other division in an actual implementation. In addition, functional modules in the embodiments of this application may be integrated into one processor, or each of the modules may exist alone physically, or two or more modules may be integrated into one module. The integrated module may be implemented in a form of hardware, or may be implemented in a form of a software functional module.

When each functional module is obtained through division based on each corresponding function,FIG.7shows a communications apparatus70according to an embodiment of this application. The communications apparatus70is configured to implement functions of the core network device in the foregoing method. The communications apparatus70may be the core network device, or may be an apparatus in the core network device, or may be an apparatus that can be used with the core network device. The communications apparatus70may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and another discrete component. As shown inFIG.7, the communications apparatus70may include an obtaining unit701and a processing unit702. The obtaining unit701is configured to perform S402inFIG.4, S504inFIG.5, S601inFIG.6, S701inFIG.6a, S1301inFIG.13, S1402inFIG.14, S1507inFIG.15, or S1609inFIG.16. The processing unit702is configured to perform S403inFIG.4, S505inFIG.5, S602inFIG.6, S702inFIG.6a, S1304inFIG.13, S1405inFIG.14, S1508inFIG.15, or S1610inFIG.16. All related content of the steps in the foregoing method embodiments may be cited in function descriptions of corresponding functional modules. Details are not described herein again.

Further, as shown inFIG.7, the communications apparatus70may further include a sending unit703, configured to perform S503ainFIG.5, S1305inFIG.13, S1406inFIG.14, S1504inFIG.15, or S1604and S1608inFIG.16.

FIG.8shows a communications apparatus80according to an embodiment of this application. The communications apparatus80is configured to implement functions of the core network device in the foregoing method. The communications apparatus80may be the core network device, or may be an apparatus in the core network device, or may be an apparatus that can be used with the core network device. The communications apparatus80may be a chip system. The communications apparatus80includes at least one processing module801, configured to implement the functions of the core network device in the method provided in the embodiments of this application. For example, the processing module801may be configured to perform the processes S402and S403inFIG.4, the processes S504and S505inFIG.5, the processes S601and S602inFIG.6, the processes S701and S702inFIG.6a, S1301and S1304inFIGS.13, S1402and S1405inFIGS.14, S1507and S1508inFIG.15, or S1609and S1610inFIG.16. For details, refer to detailed descriptions in the method examples. Details are not described herein again.

The communications apparatus80may further include at least one storage module802, configured to store a program instruction and/or data. The storage module802is coupled to the processing module801. Coupling in this embodiment of this application is an indirect coupling or a communication connection between apparatuses, units, or modules, may be in an electrical form, a mechanical form, or another form, and is used for information exchange between the apparatuses, the units, or the modules. The processing module801may operate in collaboration with the storage module802. The processing module801may execute the program instruction stored in the storage module802. At least one of the at least one storage module may be included in the processing module.

The communications apparatus80may further include a communications module803, configured to communicate with another device through a transmission medium, so as to determine that an apparatus in the communications apparatus80can communicate with the another device. The communications module803is configured for communication between the apparatus and the another device. For example, the processing module801performs the process S503ainFIG.5, S1305inFIG.13, S1406inFIG.14, S1504inFIG.15, or S1604and S1608inFIG.16by using the communications module803.

When the processing module801is a processor, the storage module802is a memory, and the communications module803is a communications interface, the communications apparatus80inFIG.8in this embodiment of this application may be the communications apparatus30shown inFIG.3.

As described above, the communications apparatus70or the communications apparatus80provided in this embodiment of this application may be configured to implement the functions of the core network device that are in the method implemented in the foregoing embodiments of this application. For ease of description, only a part related to this embodiment of this application is shown. For specific technical details that are not disclosed, refer to the embodiments of this application.

When each functional module is obtained through division based on each corresponding function,FIG.9shows a communications apparatus90according to an embodiment of this application. The communications apparatus90is configured to implement functions of the V2X terminal in the foregoing method. The communications apparatus90may be the V2X terminal, or may be an apparatus in the V2X terminal, or may be an apparatus that can be used with the V2X terminal. The communications apparatus90may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and another discrete component. As shown inFIG.9, the communications apparatus90may include a determining unit901and a sending unit902. The determining unit901is configured to determine that the V2X terminal transmits V2X service data through PC5 interface communication in a base station scheduling mode, or the V2X terminal transmits V2X service data by using a spectrum controlled by a current camped cell. The sending unit902is configured to perform the processes S401and S404inFIG.4, S1301inFIGS.13, S1402and S1407inFIGS.14, S1501and S1506inFIG.15, or S1601and S1606inFIG.16. All related content of the steps in the foregoing method embodiments may be cited in function descriptions of corresponding functional modules. Details are not described herein again.

FIG.10shows a communications apparatus100according to an embodiment of this application. The communications apparatus100is configured to implement functions of the V2X terminal in the foregoing method. The communications apparatus100may be the V2X terminal, or may be an apparatus in the V2X terminal, or may be an apparatus that can be used with the V2X terminal. The communications apparatus100may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and another discrete component. The communications apparatus100includes at least one processing module1001, configured to implement the functions of the V2X terminal in the method provided in the embodiments of this application. For example, the processing module1001may be configured to determine that the V2X terminal transmits V2X service data through PC5 interface communication in a base station scheduling mode, or the V2X terminal transmits V2X service data by using a spectrum controlled by a current camped cell. For details, refer to detailed descriptions in the method examples. Details are not described herein.

The communications apparatus100may further include at least one storage module1002, configured to store a program instruction and/or data. The storage module1002is coupled to the processing module1001. Coupling in this embodiment of this application is an indirect coupling or a communication connection between apparatuses, units, or modules, may be in an electrical form, a mechanical form, or another form, and is used for information exchange between the apparatuses, the units, or the modules. The processing module1001may operate in collaboration with the storage module1002. The processing module1001may execute the program instruction stored in the storage module1002. At least one of the at least one storage module may be included in the processing module.

The communications apparatus100may further include a communications module1003, configured to communicate with another device through a transmission medium, so that an apparatus in the communications apparatus100can communicate with the another device. The communications module1003is configured for communication between the apparatus and the another device. For example, the processing module1001performs the processes S401and S404inFIG.4, S1301inFIGS.13, S1402and S1407inFIGS.14, S1501and S1506inFIG.15, or S1601and S1606inFIG.16by using the communications module1003.

When the processing module1001is a processor, the storage module1002is a memory, and the communications module1003is a communications interface, the communications apparatus100inFIG.10in this embodiment of this application may be the communications apparatus30shown inFIG.3.

As described above, the communications apparatus90or the communications apparatus100provided in this embodiment of this application may be configured to implement the functions of the V2X terminal that are in the method implemented in the foregoing embodiments of this application. For ease of description, only a part related to this embodiment of this application is shown. For specific technical details that are not disclosed, refer to the embodiments of this application.

When each functional module is obtained through division based on each corresponding function,FIG.11shows a communications apparatus110according to an embodiment of this application. The communications apparatus110is configured to implement functions of the access network device in the foregoing method. The communications apparatus110may be the access network device, or may be an apparatus in the access network device, or may be an apparatus that can be used with the access network device. The communications apparatus1100may be a chip system. In this embodiment of this application, the chip system may include a chip, or may include a chip and another discrete component. As shown inFIG.11, the communications apparatus110may include a receiving unit1101and a sending unit1102. The receiving unit1101is configured to perform S502and S503binFIGS.5, S1504and S1506inFIG.15, or S1604, S1606, and S1608inFIG.16. The sending unit1102is configured to perform S503inFIGS.5, S1505and S1507inFIG.15, or S1605, S1609, and S1612inFIG.16. All related content of the steps in the foregoing method embodiments may be cited in function descriptions of corresponding functional modules. Details are not described herein again.

FIG.12shows a communications apparatus120according to an embodiment of this application. The communications apparatus120is configured to implement functions of the access network device in the foregoing method. The communications apparatus120may be the access network device, or may be an apparatus in the access network device, or may be an apparatus that can be used with the access network device. The communications apparatus120may be a chip system. The communications apparatus120includes at least one processing module1201, configured to implement functions of the access network device in the method provided in the embodiments of this application. For details, refer to detailed descriptions in the method examples. Details are not described herein again.

The communications apparatus120may further include at least one storage module1202, configured to store a program instruction and/or data. The storage module1202is coupled to the processing module1201. Coupling in this embodiment of this application is an indirect coupling or a communication connection between apparatuses, units, or modules, may be in an electrical form, a mechanical form, or another form, and is used for information exchange between the apparatuses, the units, or the modules. The processing module1201may operate in collaboration with the storage module1202. The processing module1201may execute the program instruction stored in the storage module1202. At least one of the at least one storage module may be included in the processing module.

The communications apparatus120may further include a communications module1203, configured to communicate with another device through a transmission medium, so as to determine that an apparatus in the communications apparatus120can communicate with the another device. The communications module1203is configured for communication between the apparatus and the another device. For example, the processing module1201performs the processes S502, S503, and S503binFIGS.5, S1504, S1505, S1506, and S1507inFIG.15, or S1604, S1605, S1606, S1608, S1609and S1612inFIG.16by using the communications module1203.

When the processing module1201is a processor, the storage module1202is a memory, and the communications module1203is a communications interface, the communications apparatus120inFIG.12in this embodiment of this application may be the communications apparatus30shown inFIG.3.

As described above, the communications apparatus110or the communications apparatus120provided in this embodiment of this application may be configured to implement the functions of the core network device that are in the method implemented in the foregoing embodiments of this application. For ease of description, only a part related to this embodiment of this application is shown. For specific technical details that are not disclosed, refer to the embodiments of this application.

Solutions provided in the embodiments of this application are described in detail below by using specific examples.

According to one aspect, an embodiment of this application provides a communications method. The communications method is applied to an interaction process between a V2X terminal (V2X UE), an access network device (NG-RAN), and a core network device (AMF) in a 5G communications system.FIG.13is a flowchart of the communications method. As shown inFIG.13, the method may include the following steps.

S1301. The V2X UE has a mode1PC5 communication requirement, and the V2X UE sends a registration request message to the AMF, where the registration request message carries an information element for not releasing an N2 connection.

The information element for not releasing an N2 connection is the explicit indication information in the manner2described in S401. A function of the information element “not release an N2 connection” is: requesting to maintain or skip releasing an N1connection between the AMF and the V2X UE, or requesting to maintain or skip releasing the N2 connection of the V2X UE between the AMF and the NG-RAN of the V2X UE, requesting to maintain or skip releasing an RRC connection between the V2X UE and the NG-RAN, requesting the NG-RAN to reserve an internally stored context of the V2X UE, or request the V2X UE to maintain a connected mode.

It should be noted that the registration request message in S1301is based on the registration request message in S201, and carries the information element for not releasing an N2 connection.

S1302. The AMF obtains subscription information of the V2X UE from UDM based on identification information of the V2X UE.

It should be noted that for specific implementation of S1302, refer to S202. Details are not described herein again.

S1303. The AMF selects a PCF, and establishes an AMF-PCF association relationship.

It should be noted that for specific implementation of S1303, refer to S203. Details are not described herein again.

S1304. The AMF maintains or skips releasing a communication connection of the V2X UE between the AMF and the access network device of the V2X terminal based on the information element for not releasing an N2 connection.

In S1304, the AMF may determine, based on the information element “not release an N2 connection” in the registration request message and at least one of the following information: a type of the V2X UE (for example, a type of UE is V2X), capability information of the V2X UE (for example, the UE supports PC5 interface communication), and capability information of the NG-RAN (for example, the NG-RAN supports the PC5 interface communication), to maintain or skip releasing a communication connection of the V2X UE between the AMF and the access network device of the V2X terminal.

The capability information of the V2X UE may be a capability in the subscription information of the V2X UE, or may be the capability information sent by the V2X UE. This is not limited in this embodiment of this application.

For example, when the AMF receives the information element for not releasing an N2 connection, and subscription information of the UE indicates that the type of the UE is V2X, the AMF does not release the N2 connection.

For another example, when the AMF receives the information element for not releasing an N2 connection, and the UE supports the PC5 interface communication, the AMF does not release the N2 connection.

For another example, when the AMF receives the information element for not releasing an N2 connection, subscription information of the UE indicates that the type of the UE is V2X, and the UE supports the PC5 interface communication, the AMF does not release the N2 connection.

It should be noted that for specific implementation of S1304, refer to S403. Details are not described herein again.

S1305. The AMF sends a registration accept message to the V2X UE.

In a possible implementation, for S1305, refer to specific implementation of S204. Details are not described herein again.

In another possible implementation, S1305may be implemented as S1305ato S1305c.

S1305a. The AMF sends an NGAP message to the NG-RAN.

The NGAP message includes a registration accept message and a second indication.

The second indication is used to indicate the NG-RAN to maintain or skip releasing the N2 connection of the V2X UE between the AMF and the NG-RAN.

S1305b. The NG-RAN sets first duration based on the second indication.

For specific implementation of S1305b, refer to S407b. Details are not described herein again.

S1305c. The NG-RAN sends an RRC message to the V2X UE, where the RRC message carries the registration accept message.

According to another aspect, an embodiment of this application provides a communications method. The communications method is applied to an interaction process between a V2X terminal (V2X UE), an access network device (NG-RAN), and a core network device (AMF) in a 5G communications system.FIG.14is a flowchart of the communications method. As shown inFIG.14, the method may include the following steps.

S1401. The V2X UE has a mode1PC5 communication requirement, and the V2X UE triggers a registration procedure+a service request procedure (Registration Request+Service Request).

S1402: The V2X UE sends a registration request message to the AMF, where the registration request message carries an identifier (identity, ID) of a follow-on request.

The ID of the follow-on request is the first indication described in S401, and is used to indicate that there is to-be-processed uplink signaling in the V2X UE.

It should be noted that the registration request message in S1402is based on the registration request message in S201, and carries the ID of the follow-on request.

S1403. The AMF obtains subscription information of the V2X UE from UDM based on identification information of the V2X UE.

It should be noted that for specific implementation of S1403, refer to S202. Details are not described herein again.

S1404. The AMF selects a PCF, and establishes an AMF-PCF association relationship.

It should be noted that for specific implementation of S1404, refer to S203. Details are not described herein again.

S1405. The AMF maintains or skips releasing a communication connection of the V2X UE between the AMF and the NG-RAN of the V2X terminal based on the ID of the follow-on request.

In S1405, the AMF may maintain or skip releasing the communication connection of the V2X UE between the AMF and the access network device of the V2X terminal based on the ID of the follow-on request in the registration request message, and the subscription information of the V2X UE (for example, the type of the UE is V2X) or capability information of the V2X UE (for example, the UE supports PC5 interface communication).

The capability information of the V2X UE may be a capability in the subscription information of the V2X UE, or may be the capability information sent by the V2X UE. This is not limited in this embodiment of this application.

S1406. The AMF sends a registration accept message to the V2X UE.

In a possible implementation, for S1406, refer to specific implementation of S204. Details are not described herein again.

In another possible implementation, S1406may be implemented as S1406ato S1406c.

S1406a. The AMF sends an NGAP message to the NG-RAN.

The NGAP message includes a registration accept message and a second indication. The second indication is used to indicate the NG-RAN to maintain or skip releasing an N2 connection of the V2X UE between the AMF and the NG-RAN.

S1406b. The NG-RAN sets first duration based on the second indication.

For specific implementation of S1406b, refer to S407b. Details are not described herein again.

S1406c. The NG-RAN sends an RRC message to the V2X UE, where the RRC message carries the registration accept message.

S1407. After receiving the registration accept message, the V2X UE sends a service request (SR) message to the AMF.

The SR message is used to request not to activate a user plane resource.

For example, the SR message is used to maintain the V2X UE in a connected mode, or is used to maintain the N2 connection, or is used for not releasing the N2 connection. The SR message does not carry an information element of a PDU session to be activated. That is, the UE does not further activate the user plane resource (in other words, does not activate a PDU session).

S1408. The AMF receives the SR message.

In S1408, the AMF performs “Service Request procedures” in the standard 3GPP TS 23.502. A process is the same as a process in which the V2X terminal switches from an idle mode to the connected mode. Details are not described herein again.

According to yet another aspect, an embodiment of this application provides yet another communications method. The communications method is applied to an interaction process between a V2X terminal (V2X UE), an access network device (NG-RAN), and a core network device (AMF) in a 5G communications system.FIG.15is a flowchart of the communications method. As shown inFIG.15, the method may include the following steps.

S1501. The V2X UE sends a registration request message to the AMF.

It should be noted that for specific implementation of S1501, refer to S201. Details are not described herein again.

S1502. The AMF obtains subscription information of the V2X UE from UDM based on identification information of the V2X UE.

It should be noted that for specific implementation of S1502, refer to S202. Details are not described herein again.

S1503. The AMF selects a PCF, and establishes an AMF-PCF association relationship.

It should be noted that for specific implementation of S1503, refer to S203. Details are not described herein again.

S1504. The AMF sends an NGAP message carrying a registration accept message to the NG-RAN, and starts a T3540 timer.

After the T3540 timer expires, the AMF releases a communication connection of the V2X UE between the AMF and the access network device of the V2X terminal.

S1505. The NG-RAN sends an RRC message to the V2X UE, where the RRC message carries the registration accept message.

S1506. After the V2X UE receives the registration accept message, if the V2X UE has a mode1PC5 communication requirement, the V2X UE sends, to the NG-RAN, an RRC message for requesting a resource.

S1507. After receiving the RRC message for requesting a resource, the NG-RAN sends an NGAP message to the AMF, where the NGAP message carries indication information.

The indication information may be used to notify the AMF that the V2X UE is performing PC5 interface communication.

In a possible implementation, S1507may be replaced with the following: After the NG-RAN receives the RRC message for requesting a resource, if the V2X UE is in a connected mode, the NG-RAN sends an NGAP message to the AMF, where the NGAP message carries indication information. That is, this solution is applicable only to a case in which the T3540 timer of the AMF does not expire.

S1508. The AMF stops the T3540 timer based on the indication information.

In S1508, the AMF stops the T3540 timer based on the indication information, to maintain or skip releasing the communication connection of the V2X UE between the AMF and the access network device of the V2X terminal.

According to yet another aspect, an embodiment of this application provides yet another communications method. The communications method is applied to an interaction process between a V2X terminal (V2X UE), an access network device (NG-RAN), and a core network device (AMF) in a 5G communications system.FIG.16is a flowchart of the communications method. As shown inFIG.16, the method may include the following steps.

S1601. The V2X UE sends a registration request message to the AMF.

It should be noted that for specific implementation of S1601, refer to S201. Details are not described herein again.

S1602. The AMF obtains subscription information of the V2X UE from UDM based on identification information of the V2X UE.

It should be noted that for specific implementation of S1602, refer to S202. Details are not described herein again.

S1603. The AMF selects a PCF, and establishes an AMF-PCF association relationship.

It should be noted that for specific implementation of S1603, refer to S203. Details are not described herein again.

S1604. The AMF sends an NGAP message carrying a registration accept message to the NG-RAN, and starts a T3540 timer.

After the T3540 timer expires, the AMF sends, to the NG-RAN, an NGAP message used to release an N2 connection, to release a communication connection of the V2X UE between the AMF and the access network device of the V2X terminal.

S1605. The NG-RAN sends an RRC message to the V2X UE, where the RRC message carries the registration accept message.

S1606. After the V2X UE receives the registration accept message, if the V2X UE has a mode1PC5 communication requirement, the V2X UE sends, to the NG-RAN, an RRC message for requesting a resource.

S1607. After receiving the RRC message for requesting a resource, the NG-RAN starts a first timer.

S1608. The NG-RAN receives the NGAP message that is sent by the AMF and that is used to release the N2 connection.

If the NG-RAN receives the NGAP message used to release the N2 connection in S1608and the first timer expires, the NG-RAN releases the N2 connection with reference to S209. When the NG-RAN receives the NGAP message used to release the N2 connection in S1608and the first timer does not expire, the NG-RAN performs S1609.

S1609. The NG-RAN sends, to the AMF, an NGAP message used to reject release of the N2 connection.

Optionally, the NGAP message that is sent by the NG-RAN to the AMF and that is used to reject release of the N2 connection may carry a specific reject cause value. The cause value may be that the V2X UE is performing mode1PC5 interface communication.

S1610. The AMF determines, based on the cause value in the NGAP message from the NG-RAN, whether an attempt to release the N2 connection needs to continue.

For example, if the N2 connection needs to be released due to an AMF failure, the AMF sends an NGAP message again. If the N2 connection needs to be released due to only a case in which the V2X UE is performing the mode1PC5 interface communication, the AMF does not further send an NGAP message.

Optionally, as shown inFIG.16, after S1609, the communications method may further include S1611and S1612, so as to avoid that the N2 connection is not released after the V2X UE mode1PC5 interface communication ends.

S1611. The NG-RAN starts a timer used to determine whether a user plane of the V2X UE is idle.

S1612. After the timer used to determine whether the user plane of the V2X UE is idle expires, the NG-RAN initiates an N2 connection release.

According to yet another aspect, an embodiment of this application provides a communications system. The communications system includes a first communications apparatus and a second communications apparatus. The first communications apparatus may implement functions of a core network device, and the second communications apparatus may implement functions of a V2X terminal. For example, the first communications apparatus is the core network device described in the embodiments of this application, and the second communications apparatus is the V2X terminal described in the embodiments of this application.

According to yet another aspect, an embodiment of this application provides a communications system. The communications system includes a third communications apparatus and a fourth communications apparatus. The third communications apparatus may implement functions of a core network device, and the fourth communications apparatus may implement functions of an access network device. For example, the third communications apparatus is the core network device described in the embodiments of this application, and the fourth communications apparatus is the access network device described in the embodiments of this application.

In another form of this embodiment, a computer-readable storage medium is provided. The computer-readable storage medium stores an instruction. When the instruction is executed, the method in the foregoing method embodiments is performed.

In another form of this embodiment, a computer program product including an instruction is provided. When the instruction is executed, the method in the foregoing method embodiments is performed.

An embodiment of this application further provides a chip system. The chip system includes a processor, configured to implement the technical methods in the embodiments of the present disclosure. In a possible design, the chip system further includes a memory, configured to store a program instruction and/or data that are/is necessary for the communications device in this embodiment of the present disclosure. In a possible design, the chip system further includes a memory, configured for the processor to invoke application program code stored in the memory. The chip system may include one or more chips, or may include a chip and another discrete device. This is not limited in this embodiment of this application.

The method or algorithm steps described with reference to the content disclosed in this application may be implemented by hardware, or may be implemented by a processor by executing a software instruction. The software instruction may include a corresponding software module. The software module may be stored in a RAM, a flash memory, a ROM, an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a register, a hard disk, a removable hard disk, a compact disc read-only memory (CD-ROM), or any other form of storage medium well-known in the art. For example, a storage medium is coupled to a processor, so that the processor can read information from the storage medium or write information into the storage medium. Certainly, the storage medium may be a component of the processor. The processor and the storage medium may be located in an ASIC. In addition, the ASIC may be located in a core network interface device. Certainly, the processor and the storage medium may exist in the core network interface device as discrete components. Alternatively, the memory may be coupled to the processor. For example, the memory may exist independently, and is connected to the processor by using a bus. Alternatively, the memory may be integrated with the processor. The memory may be configured to store application program code for executing the technical solutions provided in the embodiments of this application, and the processor controls the execution. The processor is configured to execute application program code stored in the memory, to implement the technical solutions provided in the embodiments of this application.

The foregoing descriptions about implementations allow a person skilled in the art to clearly understand that, for the purpose of convenient and brief description, division into only the foregoing functional modules is used as an example for illustration. In actual application, the foregoing functions can be allocated to different functional modules for implementation based on a requirement. That is, an inner structure of an apparatus is divided into different functional modules to implement all or some of the functions described above.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other manners. For example, the described apparatus embodiments are merely examples. For example, division into the modules or units is merely logical function division. There may be another division manner in actual implementation. For example, a plurality of units or components may be combined or may be integrated into another apparatus, or some features may be ignored or not be performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. The indirect couplings or communication connections between the apparatuses or units may be implemented in an electrical form, a mechanical form, or another form.

The units described as separate components may or may not be physically separate, and components displayed as units may be one or more physical units, that is, may be located in one place, or may be distributed on a plurality of different places. Some or all of the units may be selected based on actual requirements to achieve the objectives of the solutions of the embodiments.

In addition, functional units in the embodiments of this application may be integrated into one processing unit, or each of the units may exist alone physically, or two or more units are integrated into one unit. The integrated unit may be implemented in a form of hardware, or may be implemented in a form of a software functional unit.

When the integrated unit is implemented in a form of a software function unit and sold or used as an independent product, the integrated unit may be stored in a readable storage medium. Based on such an understanding, the technical solutions in the embodiments of this application essentially, or the part contributing to the conventional technology, or all or some of the technical solutions may be implemented in a form of a software product. The software product is stored in a storage medium and includes several instructions for instructing a device (which may be a single-chip microcomputer, a chip, or the like) or a processor to perform all or some of the steps of the method described in the embodiments of this application. The storage medium includes any medium that can store program code, for example, a USB flash drive, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disc.

The foregoing descriptions are merely specific implementations of this application, but are not intended to limit the protection scope of this application. Any variation or replacement within the technical scope disclosed in this application shall fall within the protection scope of this application. Therefore, the protection scope of this application shall be subject to the protection scope of the claims.