Communication method and device

Abstract

The invention provides a communication method and device, and belongs to the technical field of communication. In the method, an access and mobility management network element can actively indicate a session management network element to report a data volume of service data, such as a first data volume of service data cached by a network when a terminal is in an inactive state, so that the access and mobility management network element can inform an access network device of the corresponding data volume, such as a second data volume, according to the data volume. The MT SDT judgment method and device are used for more accurate MT SDT judgment of access network equipment.

Description

Technical Field

[0001] The present application relates to the field of communications, and in particular to a communication method and device. Background Art

[0002] When the radio resource control (RRC) is inactive, the terminal can enable the small data transmission (SDT) mechanism, such as mobile terminated (MT), that is, downlink MT SDT, which can transmit small amounts of data without restoring the original data radio bearer (DRB) / signaling radio bearer (SRB), thereby reducing complexity and energy consumption on the terminal side.

[0003] For example, when downlink data arrives, the user plane function (UPF) network element reports the downlink data arrival notification (DDN) message to the session management function (SMF) network element, and the SMF network element accordingly initiates the Namf service to the access and mobility management function (AMF) network element to determine whether the current UE is reachable. Subsequently, when the terminal is about to be reachable, the AMF network element notifies the radio access network (RAN) device of the arrival of downlink data to assist the RAN device in making MT SDT decisions.

[0004] However, how to ensure the accuracy of MT SDT judgment is a hot topic in current research. Summary of the invention

[0005] The embodiments of the present application provide a communication method and apparatus to ensure the accuracy of MT SDT decision.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] In a first aspect, a communication method is provided, the method comprising: an access and mobility management network element sends first information to a session management network element, and receives a first data volume from the session management network element. The first information is used to trigger the session management network element to report the data volume of cached service data of a terminal, the cached service data of the terminal is service data cached by the network when the terminal is in an inactive state, and the first data volume is the data volume of the cached service data of the terminal. In this way, the access and mobility management network element sends a second data volume to an access network device of the terminal according to the first data volume.

[0008] It can be seen from this that the access and mobility management network element can actively instruct the session management network element to report the data volume of service data, such as the first data volume of service data cached by the network when the terminal is in an inactive state, so that the access and mobility management network element can inform the access network device of the corresponding data volume, such as the second data volume, so that the access network device can make a more accurate MT SDT decision.

[0009] In a possible design scheme, the access and mobility management network element sends first information to the session management network element, including: when the state of the terminal changes to a reachable state, the access and mobility management network element sends the first information to the session management network element, so that the session management network element reports the amount of service data cached by the network during the entire unreachable state of the terminal, so as to improve the accuracy of the MT SDT judgment. The change of the state of the terminal to a reachable state can be understood as the terminal device is about to be reachable or the access and mobility management network element triggers the access network device to perform paging before.

[0010] Optionally, the method described in the first aspect may further include: the access and mobility management network element determines that the state of the terminal is changed to a reachable state. It can be understood that, compared with other devices / network elements informing the access and mobility management network element of the state change of the terminal, the access and mobility management network element determines the state change of the terminal by itself, which can avoid the delay and overhead generated by communication. For example, the access and mobility management network element determines that the state of the terminal is changed to a reachable state or is about to be changed to a reachable state based on the eDRX parameters of the terminal device, such as the eDRX cycle and the paging time window (PTW).

[0011] Optionally, the first information is carried in a session context request message, and the first data volume is carried in a session context response message, that is, existing message implementations are reused to reduce the implementation complexity of the solution, or it can also be carried in a new message to achieve decoupling from existing messages and more flexible information element transmission.

[0012] In a possible design, the first information includes first indication information, and the first indication information is used to instruct the session management network element to report the amount of cached service data of the terminal when the first timer times out. For example, when the first timer times out when the state of the terminal changes to a reachable state, the session management network element reports the amount of service data cached by the network when the terminal is in an unreachable state, thereby improving the accuracy of the MT SDT judgment.

[0013] Optionally, the method described in the first aspect may further include: the access and mobility management network element determines the duration of the first timer according to the discontinuous reception parameters of the terminal, and sends the duration of the first timer to the session management network element. The discontinuous reception parameters of the terminal can be used to indicate the eDRX cycle and / or PTW of the terminal, that is, during what time the terminal is in the awake state (or reachable state) in the inactive state, and during what time it is in the dormant state (or unreachable state). In this way, the access and mobility management network element can determine the duration of the first timer according to the time when the terminal's state changes to the reachable state, ensuring that the first timer times out when the terminal's state changes to the reachable state or when the terminal's state is about to change to the reachable state.

[0014] Optionally, the first information may also include the duration of the first timer, that is, carried in the same information as the first indication information to reduce the number of communications. Of course, the duration of the first timer and the first indication information may also be carried in different information to achieve decoupling and more flexible cell transmission.

[0015] In a possible design scheme, the first information may include second indication information, and the second indication information is used to instruct the session management network element to report the data volume of the terminal's cached service data when the data volume of the terminal's cached service data reaches a cached data volume threshold. For example, the data volume threshold may be the data volume threshold that the SDT DRB of the access network device can carry. In other words, if the data volume of the terminal's cached service data does not reach the cached data volume threshold, the access network device can execute MT SDT even if the session management network element does not report. However, if the data volume of the terminal's cached service data reaches the cached data volume threshold, the session management network element reports in a timely manner so that the access network device can restore the terminal to a connected state in a timely manner for data transmission to reduce transmission delay. Specifically, the second indication information can be used to instruct the session management network element to report the data volume of the terminal's one or more QoS flows' service data when the data volume of the terminal's one or more QoS flows' service data reaches the cached data volume threshold.

[0016] Optionally, the first information also includes a buffered data volume threshold, that is, carried in the same information as the second indication information to reduce the number of communications. Of course, the buffered data volume threshold and the second indication information can also be carried in different information to achieve decoupling and more flexible cell transmission.

[0017] Optionally, the first information is carried in a protocol data unit PDU session context update message, or the first information is carried in a mobile terminal termination MT response message, that is, the existing message implementation is reused to reduce the implementation complexity of the solution, or it can also be carried in a new message to achieve decoupling from existing messages and more flexible information element transmission.

[0018] In a possible design, the first information includes third indication information, and the third indication information is used to instruct the session management network element to report the data volume of the terminal's service data each time the network receives service data of the terminal when the terminal is in an inactive and unreachable state. In this way, the session management network element can report the data volume of the service data cached by the network during the entire unreachable state of the terminal, thereby improving the accuracy of the MT SDT decision.

[0019] Optionally, the first information is carried in the MT response message, and the first data volume is carried in the MT request message, that is, the existing message implementation is reused to reduce the implementation complexity of the solution, or it can also be carried in a new message to achieve decoupling from the existing message and more flexible information element transmission.

[0020] In a possible design scheme, the first information also includes an identifier of the first quality of service QoS flow of the terminal. The first QoS flow can be one or more. The identifier of the first QoS flow can be used to indicate that the cached service data of the terminal is the data corresponding to the first QoS flow, that is, to indicate that the session management network element reports the amount of data corresponding to the first QoS flow. Among them, the first QoS flow supports SDT DRB small data transmission data bearer. That is to say, the access and mobility management network element can instruct the session management network element to only report the amount of data corresponding to the specified QoS flow (such as the first QoS flow supporting SDT DRB) to avoid communication redundancy. Alternatively, if the first information does not include the identifier of the first QoS flow, the session management network element reports the amount of data corresponding to all QoS flows under the session of the terminal, such as reporting the amount of data corresponding to each QoS flow at the granularity of the QoS flow.

[0021] Optionally, the method described in the first aspect may further include: the access and mobility management network element receives second information from the access network device of the terminal. The second information may include information about the first QoS flow. The access and mobility management network element sends the first information to the session management network element, including: the access and mobility management network element sends the first information to the session management network element based on the information about the first QoS flow. That is to say, the access network device can selectively let the core network report the data volume of the corresponding QoS flow according to the requirements of MT SDT to avoid communication redundancy. Alternatively, when the access and mobility management network element finds that other QoS flows except the first QoS flow of the terminal have cached service data, it will not send the cached service data volume corresponding to the first QoS flow to the access network device.

[0022] Optionally, the second information may further include SDT enabling information. The SDT enabling information may be used to indicate the amount of cached service data of the terminal reported by the access and mobility management network element. For example, the information element meaning of the SDT enabling information may be to indicate that the terminal currently in an inactive state is configured with an SDT DRB, so as to implicitly indicate the amount of cached service data of the terminal reported by the access and mobility management network element by indicating the configuration of the SDT DRB. Alternatively, the information element meaning of the SDT enabling information may also be to indicate the amount of cached service data of the terminal reported by the access and mobility management network element.

[0023] Optionally, the second information also includes a data volume threshold of the SDT DRB, and the access and mobility management network element sends the first information to the session management network element, including: when the data volume of the data cached by the network is less than the data volume threshold of the SDT DRB, the access and mobility management network element sends the first information to the session management network element. The data cached by the network is the data corresponding to the first QoS flow. That is to say, when the data volume of the data cached by the network is less than the upper limit of the data volume that the SDT DRB can carry, the access and mobility management network element allows the network to continue to cache and report the data volume, otherwise, the amount of data cached by the network will not be sent to the access network device.

[0024] In a possible design scheme, the first data volume includes the data volume corresponding to at least one QoS flow of the terminal, and the second data volume is the data volume corresponding to the QoS flow supporting SDT DRB in the at least one QoS flow. It can be understood that for the QoS flow that does not support SDT DRB, even if the network caches its corresponding data, the access network device cannot transmit these data through MT SDT. In this case, the access and mobility management network element can filter the data volume to be reported and only provide the data volume corresponding to the QoS flow supporting SDT DRB to avoid communication redundancy. Alternatively, in the case where the first data volume includes the data volume corresponding to at least one QoS flow of the terminal, if the access network device performs the MT SDT decision to consider not only the data volume corresponding to the QoS flow supporting SDT DRB, but also the data volume corresponding to the QoS flow not supporting SDT DRB, then the access and mobility management network element can directly send the first data volume to the access network device, that is, the first data volume is the same as the second data volume. Alternatively, if the first data volume is the data volume corresponding to the QoS flow supporting SDT DRB, then the access and mobility management network element can also directly send the first data volume to the access network device, that is, the first data volume is the same as the second data volume.

[0025] In a possible design scheme, before the access and mobility management network element sends the first information to the session management network element, the method described in the first aspect may also include: the access and mobility management network element receives the session management network element mobile terminal termination MT request message. The MT request message includes a third data volume, and the third data volume is the data volume of the terminal's cached service data. When the terminal is in an inactive and unreachable state, the access and mobility management network element sends an MT response message to the session management network element according to the MT request message. The MT response message is used to indicate that the terminal is unreachable. That is, the access and mobility management network element can instruct the session management network element to subsequently report the data volume of the terminal's cached service data when the terminal's service data arrives at the network for the first time, so as to avoid communication redundancy, such as instructing the session management network element when no service data arrives at the network, resulting in invalid reporting.

[0026] In a second aspect, a communication method is provided, the method comprising: a session management network element receives first information from an access and mobility management network element, and sends a first data volume to the access and mobility management network element according to the first information. The first information is used to trigger the session management network element to report the data volume of cached service data of a terminal, the cached service data of the terminal is service data cached by the network when the terminal is in an inactive state, and the first data volume is the data volume of the cached service data of the terminal.

[0027] In a possible design scheme, the first information is carried in a session context request message, and the first data volume is carried in a session context response message.

[0028] Optionally, the first information includes first indication information, and the first indication information is used to indicate the session management network element to report the data volume of the service data of the terminal when the first timer times out. Accordingly, the session management network element sends the first data volume to the access and mobility management network element according to the first information, including: when the first timer times out, the session management network element sends the first data volume to the access and mobility management network element.

[0029] Optionally, the method described in the second aspect may further include: the session management network element starts the first timer when receiving the duration of the first timer from the access and mobility management network element.

[0030] Optionally, the first information also includes the duration of the first timer.

[0031] In a possible design, the first information includes second indication information, and the second indication information is used to instruct the session management network element to report the data volume of the cached service data of the terminal when the data volume of the cached service data of the terminal reaches the cached data volume threshold. Accordingly, the session management network element sends the first data volume to the access and mobility management network element according to the first information, including: when the first data volume reaches the cached data volume threshold, the session management network element sends the first data volume to the access and mobility management network element.

[0032] Optionally, the first information also includes a cache data amount threshold.

[0033] Optionally, the first information is carried in a protocol data unit PDU session context update message, or the first information is carried in a mobile terminal termination MT response message.

[0034] In a possible design scheme, the first information includes third indication information, and the third indication information is used to instruct the session management network element to report the data volume of the terminal's service data each time the network receives service data of the terminal when the terminal is in an inactive and unreachable state. Accordingly, the session management network element sends the first data volume to the access and mobility management network element based on the first information, including: when the network receives the cached service data of the terminal, the session management network element sends the cached service data received from the terminal this time to the access and mobility management network element as the first data volume.

[0035] Optionally, the first information is carried in an MT response message, and the first data volume is carried in an MT request message.

[0036] In a possible design scheme, the first information also includes an identifier of the first QoS flow of the terminal, and the identifier of the first QoS flow is used to indicate that the cached service data of the terminal is data corresponding to the first QoS flow. That is, the first data volume is the data volume of the data corresponding to the first QoS flow of the terminal.

[0037] Optionally, the first QoS flow supports SDT DRB small data transmission data bearer.

[0038] In a possible design scheme, the method described in the second aspect may also include: the session management network element obtains the first data volume locally from the session management network element based on the first information, which can avoid the delay and overhead caused by communication compared to obtaining the first data volume from other devices / network elements.

[0039] In a possible design scheme, the network element in the network includes a user plane network element, and the method described in the second aspect may also include: the session management network element obtains the first data volume from the user plane network element according to the first information. For example, the session management network element may send third information to the user plane network element according to the first information. The third information may be used to trigger the user plane network element to report the data volume of the cached service data of the terminal. In this way, the session management network element may receive the first data volume sent by the user plane network element.

[0040] Optionally, if the first information includes the above-mentioned first indication information, the third information includes fourth indication information, and the fourth indication information can be used to instruct the user plane network element to report the amount of cached service data of the terminal when the second timer times out, and the second timer is determined according to the first timer. That is, the session management network element can send the fourth indication information to the user plane network element according to the first indication information.

[0041] Furthermore, the method described in the second aspect may also include: the session management network element sends the duration of the second timer to the user plane network element.

[0042] Furthermore, the third information also includes the duration of the second timer.

[0043] Optionally, if the first information includes the second indication information, the third information includes fifth indication information, and the fifth indication information is used to instruct the user plane network element to report the data volume of the cached service data of the terminal when the data volume of the cached service data of the terminal reaches the cached data volume threshold. That is, the session management network element can send the fifth indication information to the user plane network element according to the second indication information.

[0044] Furthermore, the third information may also include a cache data amount threshold.

[0045] Optionally, if the first information includes the third indication information, the third information includes sixth indication information, and the sixth indication information may be used to instruct the user plane network element to report the data volume of the terminal's service data each time the user plane network element receives service data of the terminal when the terminal is in an inactive and unreachable state. That is, the session management network element may send the sixth indication information to the user plane network element according to the third indication information.

[0046] Optionally, the third information may also include an identifier of the first QoS flow of the terminal, and the identifier of the first QoS flow may be used to instruct the user plane network element to report the amount of data corresponding to the first QoS flow. If the third information does not include the identifier of the first QoS flow, the user plane network element reports the amount of data corresponding to all QoS flows under the session of the terminal or the amount of data corresponding to all QoS flows with cached data, such as reporting the amount of data corresponding to each QoS flow at the granularity of the QoS flow.

[0047] Furthermore, the first QoS flow supports SDT DRB.

[0048] In addition, the technical effects of the method described in the second aspect can also refer to the technical effects of the method described in the first aspect, and will not be repeated here.

[0049] In a third aspect, a communication method is provided, the method comprising: an access and mobility management network element receives signaling to be sent to a terminal in an unreachable state (for example, the terminal may be in an unreachable state in an inactive state); the access and mobility management network element sends relevant information of the signaling to an access network device of the terminal. The relevant information of the signaling is used by the access network device to determine whether a small data transmission SDT is used to transmit the signaling. For example, the relevant information of the signaling includes the data volume of the signaling.

[0050] It can be seen that when the access and mobility management network element receives signaling to be sent to a terminal in an unreachable state, it can inform the access network device of the relevant information of the signaling (such as data volume) so that the access network device can make a more accurate MT SDT decision.

[0051] In a possible design scheme, the access and mobility management network element sends relevant information of signaling to the access network device of the terminal, including: when the state of the terminal changes to a reachable state, the access and mobility management network element sends relevant information of signaling to the access network device, that is, the access and mobility management network element can send the data volume of the signaling to be sent to the terminal by the network during the entire unreachable state of the terminal to the access network device, so as to improve the accuracy of the MT SDT judgment. Among them, the state of the terminal changes to a reachable state can be understood as the terminal device is about to be reachable or the access and mobility management network element triggers the access network device to perform paging.

[0052] In a fourth aspect, a communication device is provided. The communication device includes: a module for executing the method described in any one of the first aspect to the third aspect, such as a transceiver module and a processing module. For example, the transceiver module is used to indicate the transceiver function of the communication device, and the processing module is used to execute functions of the communication device other than the transceiver function.

[0053] Optionally, the transceiver module may include a sending module and a receiving module, wherein the sending module is used to implement the sending function of the communication device described in the fourth aspect, and the receiving module is used to implement the receiving function of the communication device described in the fourth aspect.

[0054] Optionally, the communication device described in the fourth aspect may further include a storage module, wherein the storage module stores a program or instruction. When the processing module executes the program or instruction, the communication device may execute the method described in any one of the first aspect to the third aspect.

[0055] It can be understood that the communication device described in the fourth aspect can be a network device, or a chip (system) or other parts or components that can be set in the network device, or a device that includes a network device, and this application does not limit this.

[0056] In addition, the technical effects of the communication device described in the fourth aspect can refer to the technical effects of the methods described in any one of the first to third aspects, and will not be repeated here.

[0057] In a fifth aspect, a communication device is provided. The communication device includes: a module for executing the method described in any one of the first aspect to the third aspect, such as a transceiver module and a processing module. For example, the transceiver module is used to indicate the transceiver function of the communication device, and the processing module is used to execute functions of the communication device other than the transceiver function.

[0058] Optionally, the transceiver module may include a sending module and a receiving module, wherein the sending module is used to implement the sending function of the communication device described in the fifth aspect, and the receiving module is used to implement the receiving function of the communication device described in the fifth aspect.

[0059] Optionally, the communication device described in the fifth aspect may further include a storage module, wherein the storage module stores a program or instruction. When the processing module executes the program or instruction, the communication device may execute the method described in any one of the first aspect to the third aspect.

[0060] It can be understood that the communication device described in the sixth aspect can be a network device, or a chip (system) or other parts or components that can be set in the network device, or a device that includes a network device, and this application does not limit this.

[0061] In addition, the technical effects of the communication device described in the fifth aspect can refer to the technical effects of the methods described in any one of the first to third aspects, and will not be repeated here.

[0062] According to a sixth aspect, a communication device is provided, wherein the communication device comprises: a processor, wherein the processor is configured to execute the method described in any one of the first aspect to the third aspect.

[0063] In a possible design solution, the communication device described in the sixth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the sixth aspect to communicate with other communication devices.

[0064] In a possible design scheme, the communication device described in the sixth aspect may also include a memory. The memory may be integrated with the processor or may be separately provided. The memory may be used to store the computer program and / or data involved in the method described in any one of the first aspect to the third aspect.

[0065] In an embodiment of the present application, the communication device described in the sixth aspect may be the network device described in any one of the first to third aspects, or a chip (system) or other parts or components that may be arranged in the network device, or a device including the network device.

[0066] In addition, the technical effects of the communication device described in the sixth aspect can refer to the technical effects of the methods described in any one of the first to third aspects, and will not be repeated here.

[0067] In a seventh aspect, a communication device is provided, comprising: a processor, the processor being coupled to a memory, the processor being configured to execute a computer program stored in the memory, so that the communication device executes the method described in any one of the first to third aspects.

[0068] In a possible design solution, the communication device described in the seventh aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the seventh aspect to communicate with other communication devices.

[0069] In an embodiment of the present application, the communication device described in the seventh aspect may be the network device described in any one of the first to third aspects, or a chip (system) or other parts or components that may be arranged in the network device, or a device including the network device.

[0070] In addition, the technical effects of the communication device described in the seventh aspect can refer to the technical effects of the methods described in any one of the first to third aspects, and will not be repeated here.

[0071] In an eighth aspect, a communication device is provided, comprising: a processor and a memory; the memory is used to store a computer program, and when the processor executes the computer program, the communication device executes the method described in any one of the first to third aspects.

[0072] In a possible design solution, the communication device described in the eighth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the eighth aspect to communicate with other communication devices.

[0073] In an embodiment of the present application, the communication device described in the eighth aspect may be the network device described in any one of the first to third aspects, or a chip (system) or other parts or components that may be arranged in the network device, or a device including the network device.

[0074] In addition, the technical effects of the communication device described in the eighth aspect can refer to the technical effects of the methods described in any one of the first to third aspects, and will not be repeated here.

[0075] In a ninth aspect, a communication system is provided, which includes at least two devices in the first to third aspects.

[0076] In a tenth aspect, a computer-readable storage medium is provided, comprising: a computer program or instructions; when the computer program or instructions are executed on a computer, the computer executes the method described in any one of the first to third aspects.

[0077] In an eleventh aspect, a computer program product is provided, comprising a computer program or instructions, which, when executed on a computer, causes the computer to execute the method described in any one of the first to third aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a schematic diagram of the architecture of a 5G mobile communication system;

[0079] Figure 2 A schematic diagram of the architecture of a communication system provided in an embodiment of the present application;

[0080] Figure 3 Schematic diagram of the communication method provided in the embodiment of the present application Figure 1 ;

[0081] Figure 4 Schematic diagram of the communication method provided in the embodiment of the present application Figure 2 ;

[0082] Figure 5 Schematic diagram of the communication method provided in the embodiment of the present application Figure 3 ;

[0083] Figure 6 Schematic diagram of the communication method provided in the embodiment of the present application Figure 4 ;

[0084] Figure 7Schematic diagram of the communication method provided in the embodiment of the present application Figure 5 ;

[0085] Figure 8 Schematic diagram of the communication method provided in the embodiment of the present application Figure 6 ;

[0086] Fig. 9 A schematic diagram of the structure of the communication device provided in the embodiment of the present application Figure 1 ;

[0087] Fig.10 A schematic diagram of the structure of the communication device provided in the embodiment of the present application Figure 2 . DETAILED DESCRIPTION

[0088] For ease of understanding, the technical terms and application architecture involved in the embodiments of the present application are first introduced below.

[0089] 1. Fifth generation (5G) mobile communication system (referred to as 5G system (5G system, 5GS)):

[0090] Figure 1 Figure 5 is a schematic diagram of the 5GS architecture. Figure 1 As shown, 5GS includes: access network (AN) and core network (CN), and may also include: terminals.

[0091] The terminal may be one or more, such as a first terminal, a second terminal, a third terminal, etc. The terminal may be a terminal with transceiver functions, or may be a chip or chip system provided in the terminal. The terminal may also be referred to as user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station (MS), mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device. The terminal in the embodiments of the present application can be a mobile phone, a cellular phone, a smart phone, a tablet computer, a wireless data card, a personal digital assistant (PDA), a wireless modem, a handset, a laptop computer, a machine type communication (MTC) terminal, a computer with a wireless transceiver function, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a smart home device (for example, a refrigerator, a television, an air conditioner, an electric meter, etc.), an intelligent robot, a robotic arm, a workshop equipment, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a vehicle-mounted terminal, a roadside unit with a terminal function, and a wireless terminal in a smart city. unit, RSU), etc., flying equipment (e.g., intelligent robot, hot air balloon, drone, airplane), etc. The terminal of the present application may also be a vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit built into the vehicle as one or more components or units. The terminal device may also be other devices with terminal functions, for example, the terminal device may also be a device that functions as a terminal in D2D communication.

[0092] The embodiments of the present application do not limit the device form of the terminal. The device for realizing the function of the terminal device can be a terminal device; it can also be a device that can support the terminal device to realize the function, such as a chip system. The device can be installed in the terminal device or used in combination with the terminal device. In the embodiments of the present application, the chip system can be composed of chips, or it can include chips and other discrete devices.

[0093] The above-mentioned AN is used to implement access-related functions, can provide network access functions for authorized users in a specific area, and can determine transmission links of different qualities to transmit user data according to the user level, business requirements, etc. AN forwards control signals and user data between the terminal and CN. AN may include: access network equipment, also known as RAN equipment. CN is mainly responsible for maintaining the subscription data of the mobile network and providing terminal functions such as session management, mobility management, policy management and security authentication. CN mainly includes the following network elements: UPF network element, authentication service function (authentication server function, AUSF) network element, AMF network element, SMF network element, network slice selection function (network slice selection function, NSSF) network element, network exposure function (network exposure function, NEF) network element, network function repository function (NF repository function, NRF) network element, policy control function (policy control function, PCF) network element, unified data management (unified data management, UDM) network element, unified data storage (unified data repository, UDR), and application function (application function, AF).

[0094] RAN equipment, that is, access network devices can be one or more. The access network device can be a device with wireless transceiver functions, or it can also be a chip or chip system arranged on the device, located in the access network (access network, AN) of the communication system, to provide access services for the terminal. For example, the access network device can be called a radio access network device (RAN) device, which can specifically be a next-generation mobile communication system, such as a 6G access network device, such as a 6G base station, or in the next-generation mobile communication system, the access network device can also have other naming methods, which are all covered within the scope of protection of the embodiments of the present application, and the present application does not impose any limitation on this. Alternatively, the access network device may also include 5G, such as a gNB in ​​a new radio (NR) system, or one or a group of antenna panels (including multiple antenna panels) of a base station in 5G, or a network node constituting a gNB, a transmission point (TRP or transmission point, TP) or a transmission measurement function (TMF), such as a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU), an RSU with a base station function, or a wired access gateway, or a core network element of 5G. Alternatively, the access network device may also include: an access point (AP) in a wireless fidelity (WiFi) system, a wireless relay node, a wireless backhaul node, various forms of macro base stations, micro base stations (also called small stations), relay stations, access points, wearable devices, vehicle-mounted devices, etc.

[0095] Among them, CU and DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU). RU can be included in a radio frequency device or a radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU) or a remote radio head (RRH). It can be understood that the network device can be a CU node, or a DU node, or a device including a CU node and a DU node. In addition, CU can be divided into a network device in the access network RAN, and CU can also be divided into a network device in the core network CN, which is not limited here.

[0096] In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU (open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, CU, CU-CP, CU-UP, DU and RU are described as examples in this application. Any unit of CU (or CU-CP, CU-UP), DU and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

[0097] The UPF network element is mainly responsible for user data processing (forwarding, receiving, billing, etc.). For example, the UPF network element can receive user data from the data network (DN) and forward the user data to the terminal through the access network device. The UPF network element can also receive user data from the terminal through the access network device and forward the user data to the DN. The DN network element refers to the operator network that provides data transmission services to users. For example, the Internet Protocol (IP) Multimedia Service (IMS), the Internet, etc. DN can be an operator's external network or a network controlled by an operator, which is used to provide business services to terminal devices.

[0098] The AUSF network element is mainly used to perform terminal security authentication.

[0099] The AMF network element is mainly used for mobility management in mobile networks, such as user location update, user network registration, user switching, etc.

[0100] SMF network elements are mainly used for session management in mobile networks, such as session establishment, modification, and release. Specific functions include allocating Internet Protocol (IP) addresses to users and selecting UPF network elements that provide data packet forwarding functions.

[0101] The PCF network element mainly supports providing a unified policy framework to control network behavior, provides policy rules to the control layer network functions, and is responsible for obtaining user subscription information related to policy decisions. The PCF network element can provide policies to the AMF network element and SMF network element, such as quality of service (QoS) policy and slice selection policy.

[0102] The NSSF network element is mainly used to select network slices for terminals.

[0103] NEF network elements are mainly used to support the opening of capabilities and events.

[0104] UDM network elements are mainly used to store user data, such as contract data, authentication / authorization data, etc.

[0105] The UDR network element is mainly used to store structured data, including contract data and policy data, externally exposed structured data, and application-related data.

[0106] AF mainly supports interaction with CN to provide services, such as influencing data routing decisions, policy control functions, or providing some third-party services to the network side.

[0107] 2. 5G Internet of Things (IoT) energy saving:

[0108] NR machine type communications (MTC), such as massive machine type communications (mMTC), is one of the important application scenarios of 5G networks, mainly for various IoT business applications based on cellular networks. Different from low power wide area (LPWA), the typical application scenarios of NR MTC include video surveillance (surveillance cameras, etc.), industrial sensor networks (such as temperature sensors, pressure sensors, etc.), wearable devices (smart bracelets, smart watches, smart glasses, etc.), etc. In order to support the low power consumption requirements of IoT devices, the 3rd Generation Partnership Project (3GPP) defined in R18 the extended discontinuous reception (eDRX) that can enhance the RRC inactive state, that is, long eDRX, whose eDRX cycle is greater than 10.24s, to ensure that the terminal can sleep for a longer time in the RRC inactive state. This also brings new demands to CN, so the standard introduces CN to assist RAN equipment to process downlink communications, such as CN to help cache downlink data of terminals in long eDRX.

[0109] Specifically, when a terminal supporting REDCAP registers to the network side, the network may select an AMF network element that supports long-latency communication capabilities for the terminal based on local policy configuration, where the long-latency communication capabilities may include: the ability to manage the reachability of long eDRX terminals, and the ability to support the instructing caching of downlink data in the SMF network element / UPF network element cache when the terminal is unreachable. After configuring the long eDXR of the terminal, the RAN device can indicate to the AMF network element that the terminal has entered or is about to enter the deactivated state and is configured with long eDRX parameters, and send the eDRX parameters to the AMF network element, and then the AMF will instruct the SMF / UPF network element to cache the downlink data of the terminal. In this way, when the downlink data of the terminal arrives at the UPF network element, the SMF / UPF network element caches the corresponding downlink data, and the UPF network element can also notify the SMF network element that the downlink data of the terminal has arrived, and the SMF network element sends a terminal reachability query request to the AMF network element to trigger paging, enabling the terminal to restore the network connection, and the SMF network element can also indicate whether to support extended cache capability (long-term data cache capability). If the terminal is currently reachable, the AMF network element can trigger the RAN device to page the terminal, so that the terminal device enters the connected state, thereby sending the downlink data of the terminal to the terminal. However, if the terminal is currently unreachable, the AMF network element can inform the SMF network element of the maximum waiting time determined according to the eDRX parameters, and the SMF network element caches the downlink data of the terminal according to the maximum waiting time. Subsequently, when the terminal is about to be reachable, the AMF network element can trigger the RAN device to page the terminal through the N2 message, enabling the terminal to recover to the RRC connection state, so as to send the previously cached downlink data to the terminal through the RAN device.

[0110] 3.SDT:

[0111] In the RRC inactive state, the RAN device can enable the SDT mechanism to transmit a small amount of data without restoring the original DRB / SRB, thereby reducing complexity and energy consumption on the terminal side. When the terminal restores the original DRB / SRB, the terminal will enter the connected state, that is, the original DRB / SRB is the DRB / SRB used by the terminal in the connected state.

[0112] For example, when the terminal is released to the RRC inactive state (or inactive state), the RAN device can indicate to the terminal which DRB / SRBs are DRB / SRBs for SDT, that is, SDT DRB / SRB, or, for each DRB / SRB configuration, whether it can use SDT for DRB / SRB recovery. When the terminal has uplink data or signaling to send, the terminal can decide whether to initiate mobile initiated (mobile initiated, MO), that is, uplink, MO SDT, based on business requirements and whether the corresponding DRB / SRB is configured with SDT DRB / SRB. Of course, MO SDT can also consider data size or other information, which depends on the internal implementation of the terminal and is not restricted by the standard. If the UE decides not to trigger MO SDT transmission, the original regular DRB / SRB is restored. When there is downlink data, since the RRC inactive state is considered when the eDRX cycle is less than 10.24s, the core network will not assist the RAN device in processing downlink data or signaling, that is, the RAN device will receive downlink data from the UPF network element. The RAN device can decide whether to perform mobile termination (mobile terminated, MT), that is, downlink, MT SDT, based on whether the DRB corresponding to the downlink data is configured with SDT and the specific data volume of the downlink data. Specifically, if the RAN device decides to perform MT SDT, the RAN device will add MTSDT indication information to the paging message during downlink paging to trigger the terminal to restore the corresponding SDT DRB / SRB when restoring the connection.

[0113] After the above-mentioned long eDRX is introduced in R18, the downlink data or signaling of the terminal will be processed by CN. For details, please refer to the above-mentioned related introduction. However, since the RAN equipment cannot perceive the DRB corresponding to the downlink data and the data size of the downlink data, the current standard has supported the introduction of the QoS flow identifier corresponding to the downlink data in the above-mentioned N2 message, such as QoS flow ID, PDU session identifier (PDU Session ID) and data volume, to assist the RAN equipment in making MT SDT decisions. Specifically, when the downlink data arrives, the UPF network element reports the DDN message to the SMF network element, and the SMF network element sends a Namf service message (for example, MT Enable UE Reachability Request (Namf_MT_EnableUERechability request) message) to the AMF network element to query the UE reachability or enable UE reachability. At this time, if the terminal is currently unreachable due to reasons such as the terminal entering eDRX sleep, the AMF network element rejects the Namf service of the SMF network element and instructs the SMF network element not to initiate the corresponding Namf service again. When the terminal status is about to change to reachable status, the AMF network element can trigger the RAN device to page the terminal, and at the same time inform the RAN device of the amount of cached downlink data corresponding to each QoS flow to assist the RAN device in making MT SDT decisions. After the UE resumes the connection, whether it enters the connected state or is still in the inactive state for MO / MT SDT transmission, the AMF network element can also notify the SMF network element to cancel the cache or send the previously cached downlink data.

[0114] However, from the time when the downlink data of the terminal reaches the UPF network element to the time when the AMF network element determines that the terminal is reachable and triggers the RAN device to page the terminal, it may take the entire long eDRX cycle. During this period, the amount of downlink data cached by the SMF network element / UPF network element may change. Therefore, how the AMF network element can inform the RAN device of the latest data amount (or the accurate data amount) is a problem that needs to be solved.

[0115] In response to the above technical problems, the embodiments of the present application propose the following technical solutions.

[0116] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0117] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as wireless network systems, vehicle to everything (V2X) communication systems, device-to-device (D2D) communication systems, Internet of Vehicles communication systems, fourth generation (4G) mobile communication systems, such as long term evolution (LTE) systems, worldwide interoperability for microwave access (WiMAX) communication systems, 5G, such as NR systems, and future communication systems.

[0118] In the embodiment of the present application, "indication" may include direct indication and indirect indication, and may also include explicit indication and implicit indication. The information indicated by a certain information (such as the first indication information, the second indication information, or the third indication information, etc. below) is called information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as but not limited to, the information to be indicated can be directly indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, wherein there is an association relationship between the other information and the information to be indicated. It is also possible to indicate only a part of the information to be indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, the indication of specific information can also be realized by means of the arrangement order of each information agreed in advance (such as specified by the protocol), thereby reducing the indication overhead to a certain extent. At the same time, the common parts of each information can also be identified and uniformly indicated to reduce the indication overhead caused by indicating the same information separately.

[0119] In addition, the specific indication method can also be various existing indication methods, such as but not limited to the above-mentioned indication methods and various combinations thereof. The specific details of the various indication methods can refer to the prior art and will not be repeated herein. As can be seen from the above, for example, when there are multiple information indicating the same type, there may be a situation where the indication methods for different information are different. In the specific implementation process, the indication method can be selected according to specific needs. The embodiment of the present application does not limit the selected indication method. In this way, the indication method involved in the embodiment of the present application should be understood to cover various methods that can enable the party to be indicated to obtain the information to be indicated.

[0120] It should be understood that the information to be indicated can be sent as a whole, or divided into multiple sub-information and sent separately, and the sending period and / or sending time of these sub-information can be the same or different. The specific sending method is not limited in the embodiment of the present application. Among them, the sending period and / or sending time of these sub-information can be pre-defined, for example, pre-defined according to a protocol, or can be configured by the sending end device by sending configuration information to the receiving end device.

[0121] "Pre-definition" or "pre-configuration" can be implemented by pre-saving corresponding codes, tables or other methods that can be used to indicate relevant information in the device, and the embodiments of the present application do not limit the specific implementation method. Among them, "saving" can mean saving in one or more memories. The one or more memories can be set separately or integrated in an encoder or decoder, a processor, or a communication device. The one or more memories can also be partially set separately and partially integrated in a decoder, a processor, or a communication device. The type of memory can be any form of storage medium, which is not limited by the embodiments of the present application.

[0122] The "protocol" involved in the embodiments of the present application may refer to a protocol family in the communication field, a standard protocol with a similar protocol family frame structure, or a related protocol used in future communication systems, and the embodiments of the present application do not make specific limitations on this.

[0123] In the embodiments of the present application, descriptions such as "when...", "in the case of...", "if" and "if" all mean that the device will make corresponding processing under certain objective circumstances. It does not limit the time, nor does it require the device to have a judgment action when implementing it, nor does it mean that there are other limitations.

[0124] In the description of the embodiments of the present application, unless otherwise specified, " / " indicates that the objects associated before and after are in an "or" relationship, for example, A / B can represent A or B; "and / or" in the embodiments of the present application is only a description of the association relationship of the associated objects, indicating that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In addition, in the description of the embodiments of the present application, unless otherwise specified, "multiple" refers to two or more than two. "At least one of the following" or its similar expression refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple. In addition, in order to facilitate the clear description of the technical solution of the embodiments of the present application, in the embodiments of the present application, the words "first" and "second" are used to distinguish the same or similar items with basically the same functions and effects. Those skilled in the art will appreciate that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit the difference. At the same time, in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0125] The network architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. A person of ordinary skill in the art can appreciate that with the evolution of the network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0126] To facilitate understanding of the embodiments of the present application, first Figure 2 The communication system shown in the example is used to describe in detail the communication system applicable to the embodiment of the present application. Figure 2 A schematic diagram of the architecture of a communication system applicable to the communication method provided in an embodiment of the present application.

[0127] like Figure 2 As shown, the communication system can be applicable to the above-mentioned 5GS, mainly including: access and mobility management network element and session management network element.

[0128] The access and mobility management network element can be the AMF network element in the above-mentioned 5GS, for details, please refer to the above-mentioned related introduction, or it can be a network element used to implement the corresponding functions of access and mobility management in future communication systems, without limitation.

[0129] The session management network element can be the SMF network element in the above-mentioned 5GS, for details, please refer to the above-mentioned related introduction, or it can be a network element used to implement the corresponding functions of session management in future communication systems, and there is no limitation on this.

[0130] In the communication system, the access and mobility management network element can actively indicate the data volume of the service data reported from the session management network element, such as the first data volume of the service data cached by the network when the terminal is in an inactive state, so that the access and mobility management network element can inform the access network device of the corresponding data volume, such as the second data volume, so that the access network device can make a more accurate MT SDT decision. And / or, when the access and mobility management network element receives the signaling to be sent to the terminal in the unreachable state, it can also inform the access network device of the relevant information of the signaling (such as the data volume) so that the access network device can make a more accurate MT SDT decision. The following is a specific introduction through the implementation of the method.

[0131] It can be understood that the network referred to in the embodiments of the present application can be a network to which the terminal is registered or attached, such as an operator network, specifically a public land mobile network (PLMN), or can also be a network of other types or standards, without limitation. The "network" mentioned below can be understood as "network element / device / entity in the network" without special instructions, such as session management network element, user plane network element, access network equipment, etc., without limitation.

[0132] The following will be combined Figure 3-Figure 6 The communication method provided in the embodiment of the present application can be applied to the above communication system and specifically applied to various scenarios mentioned in the above communication system, which are specifically introduced below.

[0133] Figure 3 Schematic diagram of the communication method provided in the embodiment of the present application Figure 1 The communication method is applicable to the above communication system, and mainly involves the interaction between access and mobility management network elements, session management network elements, and user plane network elements.

[0134] like Figure 3 As shown, the process of the communication method is as follows:

[0135] S301: An access and mobility management network element sends first information to a session management network element.

[0136] Correspondingly, the session management network element receives the first information from the access and mobility management network element.

[0137] The first information may be used to trigger / indicate / request the session management network element to report the amount of cached service data of the terminal. The cached service data of the terminal may be service data cached by the network when the terminal is in an inactive state, and the service data may specifically be data corresponding to the first QoS flow of the terminal, or data to be carried by the first QoS flow.

[0138] Specifically, the first information may include an identifier of the first QoS flow, such as QFI. Further, the first information may be used to indicate the amount of data corresponding to the first QoS flow to be reported, or to indicate the amount of data corresponding to the first QoS flow cached in the reported network.

[0139] It should be noted that the data corresponding to the first QoS flow cached by the network mentioned above can be a network element in the network (such as a core network), such as a session management network element or a user plane network element, etc., which caches the data corresponding to the first QoS flow without restriction.

[0140] The first QoS flow may be one or more QoS flows of the terminal. The first QoS flow may be all or part of the QoS flows of the terminal. Specifically, the first QoS flow may be one or more PDU session bearers established by the session management network element, without limitation.

[0141] Exemplarily, assuming that all QoS flows of the terminal include QoS flows #1 to QoS flows #3, the first QoS flow may be all QoS flows of the terminal, including QoS flows #1 to QoS flows #3; or, the first QoS flow may be a part of the QoS flows of the terminal, for example, the part of the QoS flows may be different types of QoS flows, specifically including QoS flows supporting SDT DRB and QoS flows not supporting SDT DRB. Among them, the QoS flow supporting SDT DRB may refer to the DRB corresponding to the QoS flow configured with SDT DRB, and the data carried by the QoS flow can be transmitted through SDT, and the QoS flow not supporting SDT DRB may refer to the DRB corresponding to the QoS flow not configured with SDT DRB, and the data carried by the QoS flow cannot be transmitted through SDT. For another example, the part of the QoS flow may also be a QoS flow of a specified type, specifically including only QoS flows supporting SDT DRB, that is, the first QoS flow supports SDT DRB. Taking QoS flow #1 supporting SDT DRB, QoS flow #2 and QoS flow #3 not supporting SDT DRB, and the specified type is a QoS flow supporting SDT DRB as an example, then the first QoS flow only includes QoS flow #1.

[0142] It can be seen that the access and mobility management network element can send the first information, and the first information is used to instruct the session management network element to report the amount of data corresponding to the specified type of QoS flow (such as the QoS flow supporting SDT DRB). Specifically, the first information can include the specified type, which can avoid communication redundancy.

[0143] It can be understood that when the first information does not include the identifier of the first QoS flow, the session management network element can report the data volume corresponding to all QoS flows of the terminal cached by the network by default, such as reporting the data volume corresponding to each QoS flow at the granularity of the QoS flow, or reporting the data volume corresponding to the QoS flows in which downlink data has arrived or downlink data has been cached among all QoS flows.

[0144] It should be pointed out that the session management network element can report the data volume of cached service data corresponding to which QoS flows of the terminal according to the protocol pre-definition, or it can negotiate in advance with the access and mobility management network element and / or the access network device to report the data volume of cached service data corresponding to which QoS flows of the terminal. Furthermore, after receiving the first information, the session management network element reports the data volume of these QoS flows by default.

[0145] The access and mobility management network element may trigger the session management network element to report the data volume through the sending timing of the first information or the information contained in the first information, which is introduced in different ways below.

[0146] Mode 1: When the state of the terminal changes to a reachable state, the access and mobility management network element sends first information to the session management network element.

[0147] For example, the access and mobility management network element may obtain the discontinuous reception parameters of the terminal from the access network device corresponding to the terminal (such as the access network device currently accessed by the terminal) in advance, and the discontinuous reception parameters may be used to indicate the eDRX cycle and paging time window (ptw) of the terminal, that is, the time during which the terminal is in the awake state (or reachable state) in the inactive state, and the time during which it is in the dormant state (or unreachable state). In this way, the access and mobility management network element may determine the state of the terminal changes to the reachable state, or determine the time when the state of the terminal changes to the reachable state, so as to send the first information to the session management network element when or before the time is reached, such as sending a session context request message carrying the first information.

[0148] It should be pointed out that the first information can be carried in an existing message to reduce the implementation complexity of the solution, or it can be carried in a new message to achieve decoupling from the existing message and more flexible information element transmission.

[0149] It is understood that the state change of the terminal can also be notified to the access and mobility management network element by other devices, such as access network devices, and there is no restriction on this. The state change of the terminal can be determined by the access and mobility management network element itself, which can avoid the delay and overhead caused by the notification of other network elements.

[0150] In addition, since the network can cache the service data received from the terminal after the terminal enters the unreachable state, when the access and mobility management network element triggers the reporting of the data volume of the cached service data when the terminal state changes to the reachable state or before, the session management network element can report the data volume of the service data cached by the network during the entire unreachable state of the terminal, which can improve the accuracy of the MT SDT judgment.

[0151] It can be understood that the "access network device" mentioned in the embodiments of the present application refers to "the access network device corresponding to the terminal" or "the access network device currently accessed by the terminal" unless otherwise specified. In addition, the "terminal state changes to a reachable state" referred to in the embodiments of the present application can be broadly understood, and can be understood as that before the access and mobility management network element triggers the access network device to perform paging, the terminal state has changed to a reachable state, is about to change to a reachable state, or before changing to a reachable state, such as 10 milliseconds (ms) in advance or any possible duration, that is, in consideration of communication and processing delays, the session management network element is triggered in advance to report the data volume, so that when the access and mobility management network element sends the data volume to the access network device to execute MT SDT, the terminal can just be in a reachable state (or is about to be in a reachable state) to fully utilize the duration of the reachable state for data transmission.

[0152] Mode 2: The first information includes first indication information, and the first indication information is used to instruct the session management network element to report the data volume of the cached service data of the terminal when the first timer times out.

[0153] For example, the first timer may be a timer of a session management network element. The first timer may time out when the terminal state changes to a reachable state, so that the session management network element reports the amount of service data cached by the network during the entire unreachable state of the terminal, thereby improving the accuracy of the MT SDT decision.

[0154] In mode 2, the access and mobility management network element may multiplex the session update message or the MT message to send the first information to the session management network element. For example, when the access network device notifies the access and mobility management network element that the terminal has been or will be released to the inactive state, the access and mobility management network element may send the first information to the session management network element through a session update message, such as a PDU session context update message, and instruct the session management network element to cache the downlink data of the terminal. For another example, the access and mobility management network element may send the first information to the session management network element through an MT message, such as an MT enable UE reachability response (Namf_MT_EnableUERechability response) message. Specifically, when the terminal is in the inactive state, if the service data of the terminal arrives at the user plane network element for the first time, the user plane network element may send a data arrival notification message to the session management network element to indicate that the service data of the terminal with the third data volume has arrived, triggering the terminal to enter a reachable state. In this way, the session management network element may send an MT request message, such as an MT enable UE reachable request message, to the access and mobility management network element to trigger paging of the terminal, so that the terminal can restore the connection with the network, and optionally, indicate that the cached service data of the terminal is a third data volume. In response to the MT request message, the access and mobility management network element may determine the reachable state of the terminal, such as determining that the terminal is currently unreachable. The access and mobility management network element may send an MT response message, such as an MT enable UE reachable response message, to the session management network element in response to the MT request message to indicate that the terminal is unreachable, and the first information may also be carried in the MT response message.

[0155] It can be understood that the above-mentioned process of the access and mobility management network element triggering the session management network element to cache downlink data is usually before the downlink data arrives and triggers the session management network element to query the access and mobility management network element for the reachability of the terminal. If the access and mobility management network element has reused the PDU session context update message to send the first information to the session management network element, then when the service data of the terminal first arrives at the user plane network element, the session management network element can choose not to trigger the MT message, and wait until the timer expires, and report the data volume of the service data of the terminal cached by the network until the timer expires to the access and mobility management network element. Of course, if the access and mobility management network element does not reuse the PDU session context update message to send the first information to the session management network element, then when the session management network element first reports the data volume of the service data of the terminal through the MT enable UE reachability request message, the access and mobility management network element can take this opportunity to send the first information to the session management network element to enable the session management network element to report on demand later.

[0156] Optionally, the access and mobility management network element may also determine the duration of the first timer according to the discontinuous reception parameter of the terminal, wherein the duration of the first timer may be a maximum waiting delay, and the maximum waiting delay may indicate how long it takes for the terminal to be reachable, such as how long it takes for the terminal to wake up from eDRX.

[0157] For example, the access and mobility management network element may determine the duration of the first timer according to the timing when the state of the terminal indicated by the discontinuous reception parameter changes to a reachable state and the timing when the session management network element starts the first timer, so as to ensure that the first timer can time out when or before the state of the terminal changes to a reachable state, thereby ensuring that the access and mobility management network element can obtain the data volume corresponding to the first QoS flow in a timely manner. Specifically, when the access and mobility management network element determines the timing of sending the first information and the protocol predefines a mechanism for the session management network element to start the first timer, assuming that the mechanism for starting the first timer is that the session management network element receives the first information, the access and mobility management network element may determine the timing when the session management network element starts the first timer accordingly.

[0158] It should be noted that the mechanism for the session management network element to start the first timer can also start the first timer when the first information is received and a preset time has passed to ensure that the first timer times out before the terminal state changes to a reachable state without restriction.

[0159] For another example, the access and mobility management network element may determine the timing when the access and mobility management network element sends an N2 message to the access network device to trigger paging based on the timing when the terminal state indicated by the discontinuous reception parameter changes to a reachable state. Further, the access and mobility management network element may determine the duration of the first timer based on the timing when the access and mobility management network element sends an N2 message to the access network device to trigger paging and the timing when the session management network element starts the first timer, so as to ensure that the first timer times out before or when the access and mobility management network element triggers the RAN to perform paging, and also to ensure that the access and mobility management network element can obtain the data volume corresponding to the first QoS flow in a timely manner.

[0160] The access and mobility management network element may also send the duration of the first timer to the session management network element. For example, the duration of the first timer may also be carried in the first information, so as to be carried in the same information as the first indication information, thereby reducing the number of communications. However, this is not a limitation, and the two may also be carried in different information to achieve decoupling and more flexible information element transmission. Among them, the access and mobility management network element sending the duration of the first timer to the session management network element is an example. For example, if the session management network element locally pre-configures or pre-defines the duration of the first timer, the access and mobility management network element may not send the duration of the first timer to the session management network element.

[0161] It can be understood that the first timer can be configured with QoS flow as the granularity. For example, the duration of the first timer corresponds to the identifier of the first QoS flow in the first information, and then the first timer is configured to the first QoS flow, such as one or more QoS flows. In this case, when the first timer corresponding to a QoS flow times out, the session management network element reports the data volume corresponding to the QoS flow. Alternatively, the session management network element can also configure the first timer with QoS flow as the granularity by default.

[0162] Mode 3: the first information includes second indication information, and the second indication information is used to instruct the session management network element to report the data volume of the terminal's cached service data when the data volume of the terminal's cached service data reaches a cached data volume threshold.

[0163] Specifically, the data volume of the cached service data corresponding to one or more QoS flows of the terminal is reported. For example, if the QoS flow corresponding to the cached service data of the terminal, such as the first QoS flow, supports SDT DRB, the cached data volume threshold may be the data volume threshold that the SDT DRB of the access network device can carry, or it may be determined according to the data volume threshold. In other words, if the data volume of the cached service data of the terminal does not reach the cached data volume threshold, the access network device can execute MT SDT even if the session management network element does not report it. However, if the data volume of the cached service data of the terminal reaches the cached data volume threshold, the session management network element shall report it to the access and mobility management network element in a timely manner, and the access network device can decide not to execute MT SDT based on the data volume of the cached service data from the access and mobility management network element, so that the access network device can restore the terminal to the connected state in time for data transmission to reduce the transmission delay. The data volume threshold that the SDT DRB can carry may be obtained by the access and mobility management network element in advance from other network elements (such as access network devices), or it may be pre-configured by the access and mobility management network element or predetermined by the protocol. For another example, the cache data volume threshold can also be dynamically determined by the access and mobility management network element. For example, if the current network load is high, the access and mobility management network element dynamically determines a smaller cache data volume threshold. Conversely, if the current network load is low, the access and mobility management network element dynamically determines a larger cache data volume threshold.

[0164] It can be understood that, similar to the above-mentioned method 2, the first information can also be carried in the PDU session context update message or the MT response message, that is, the existing message implementation is reused to reduce the implementation complexity of the solution. For details, please refer to the relevant introduction of the above-mentioned method 2, which will not be repeated here. Alternatively, the first information can also be carried in a new message to achieve decoupling from the existing message and more flexible cell transmission.

[0165] Optionally, the access and mobility management network element may also send a cache data volume threshold to the session management network element. For example, the cache data volume threshold may be carried in the first information and carried in the same information as the second indication information to reduce the number of communications. Of course, the cache data volume threshold and the second indication information may also be carried in different information to achieve decoupling and more flexible information element transmission. It can be understood that the access and mobility management network element sending the cache data volume threshold to the session management network element is an example. For example, if the session management network element locally pre-configures or pre-defines the cache data volume threshold, the access and mobility management network element may not send the cache data volume threshold to the session management network element.

[0166] It can be understood that, for the session management network element, the cache data volume threshold can be configured with QoS flow as the granularity. For example, the cache data volume threshold corresponds to the identifier of the first QoS flow in the first information, so the cache data volume threshold is configured to one or more first QoS flows. In this case, if the data volume corresponding to a QoS flow exceeds the cache data volume threshold corresponding to the QoS flow, the session management network element reports the data volume corresponding to the QoS flow. Alternatively, the session management network element may also default to the cache data volume threshold with QoS flow as the granularity. In addition, the value of the cache data volume threshold corresponding to each QoS flow may be the same, or may be different. For example, in the case where each QoS flow supports SDT DRB, the cache data volume threshold corresponding to each QoS flow is the data volume threshold that the SDT DRB corresponding to each QoS flow can carry. At this time, the data volume thresholds that these SDT DRBs can carry may be different.

[0167] Mode 4: The first information includes third indication information, and the third indication information is used to instruct the session management network element to report the data volume of the terminal's service data each time the network receives service data of the terminal when the terminal is in an inactive and unreachable state.

[0168] In this way, the session management network element can report the amount of service data cached by the network during the entire unreachable state of the terminal, thereby improving the accuracy of the MT SDT decision.

[0169] It can be understood that, similar to the above-mentioned method 2, the first information can also be carried in the PDU session context update message or the MT response message, that is, the existing message implementation is reused to reduce the implementation complexity of the solution. For details, please refer to the relevant introduction of the above-mentioned method 2, which will not be repeated here. Alternatively, the first information can also be carried in a new message to achieve decoupling from the existing message and more flexible cell transmission.

[0170] It can also be understood that the session management network element can also report the amount of data received by the network each time based on the third indication information with the QoS flow as the granularity. For example, the third indication information corresponds to the identifier of the first QoS flow in the first information, which is used to indicate that when the network receives data corresponding to which QoS flow in the first QoS flow (such as one or more QoS flows) each time, the session management network element reports the amount of data corresponding to the QoS flow. Alternatively, the session management network element can also default to reporting the amount of data received by the network each time with the QoS flow as the granularity.

[0171] It can also be understood that the unreachable state of the terminal in the inactive state is associated with the terminal being in the inactive state and being configured with discontinuous reception parameters, such as the eDRX parameters of the terminal device in the inactive state being configured with a long eDRX cycle. In other words, configuring a long eDRX cycle for the inactive terminal means that the terminal is unreachable in the inactive state, or in other words, the terminal entering the inactive state is configured with a long eDRX cycle, which causes the terminal device in the inactive state to be unreachable.

[0172] S302: The session management network element sends a first data volume to the access and mobility management network element according to the first information.

[0173] Correspondingly, the access and mobility management network element receives the first data volume from the session management network element.

[0174] The first data volume may be the data volume of cached service data of the terminal, or the data volume of cached service data corresponding to the first QoS flow.

[0175] It should be understood that since the first QoS flow may be one or more QoS flows, the first data volume may also include one or more data volumes. For example, in the case of multiple QoS flows, the first data volume may include data volumes corresponding to each of the multiple QoS flows. Specifically, the session management network element may send identifiers of the multiple QoS flows and data volumes corresponding to the multiple QoS flow identifiers to the access and mobility management network element.

[0176] It should also be understood that, for different implementations of the first information, the session management network element reports the first data volume in different ways, which are described below in conjunction with the above-mentioned ways 1 to 4.

[0177] With respect to the above-mentioned method 1, the session management network element receives the first information and sends the first data volume to the access and mobility management network element.

[0178] Specifically, when the session management network element caches the service data of the terminal, the session management network element can obtain the first data volume locally after receiving the first information, and report it to the access and mobility management network element; or, when the user plane network element caches the service data of the terminal, the session management network element can find the user plane network element of the terminal based on the received first information, obtain the first data volume from the user plane network element, and report it to the access and mobility management network element.

[0179] For example, the session management network element may send third information to the user plane network element of the terminal according to the first information, such as a first N4 session modification message carrying the third information, to trigger the user plane network element to report the data volume of the service data of the terminal. The third information may also include the identifier of the first QoS flow, or may not include it. The specific principle is similar to the first information, which can be understood by reference and will not be repeated here. The third information and the first information may be the same information, that is, the session management network element may forward the first information to the user plane network element. Alternatively, the third information and the first information may also be different information, such as the session management network element obtains the third information by converting the first information into a cell format that can be recognized by the user plane network element. When the user plane network element receives the third information, it sends the first data volume to the session management network element, such as a second N4 session modification message carrying the first data volume. Accordingly, the session management network element may receive the first data volume sent by the user plane network element, and send a session context response message carrying the first data volume to the access and mobility management network element to respond to the above-mentioned session context request message. Optionally, as described above, the session context response message may further include an identifier of the first QoS flow, that is, indicating that the first data volume is a data volume corresponding to the first QoS flow.

[0180] It can be understood that if the session management network element triggers the paging process through the MT request message in advance, such as reporting the third data amount, then the first data amount reported by the session management network element at this time can be an increment compared to the third data amount, that is, the data amount of the terminal's service data cached by the network before the first information is subtracted from the third data amount to obtain the increment. Alternatively, if the session management network element has not reported the third data amount in advance, the first data amount reported by the session management network element at this time can be the total amount, that is, the data amount of the terminal's service data cached by the network before receiving the first information. Alternatively, regardless of whether the session management network element has reported the third data amount in advance, the first data amount reported by the session management network element at this time can be the total amount.

[0181] With respect to the above-mentioned method 2, the session management network element starts the first timer according to the received first indication information (refer to case 11), or triggers the user plane network element to start the second timer (refer to case 12).

[0182] Case 11:

[0183] In one example, upon receiving the duration of the first timer from the access and mobility management network element, the session management network element sets the duration of the first timer according to the received duration, and starts the first timer upon receiving the first indication information.

[0184] In another example, the session management network element is locally preconfigured with the duration of the first timer, and the session management network element may start the first timer upon receiving the first indication information.

[0185] Further, when the first timer times out, the session management network element may send the first data volume to the access and mobility management network element. For example, the session management network element may trigger the acquisition of the first data volume according to the timeout of the first timer, and send the first data volume to the access and mobility management network element. Optionally, the session management network element may also send an identifier of the first QoS flow, that is, indicating that the first data volume is the data volume corresponding to the first QoS flow.

[0186] Similar to the above-mentioned method 1, if the session management network element caches the service data of the terminal, the session management network element can obtain the first data volume locally and report it to the access and mobility management network element. If the user plane network element caches the service data of the terminal, the session management network element can obtain the first data volume from the user plane network element. For specific implementation, please refer to the relevant introduction of the above-mentioned method 1, which will not be repeated here. In this way, the session management network element can send the first data volume to the access and mobility management network element, such as a Namf_MT service message carrying the first data volume. Optionally, the Namf MT service message can also carry the identifier of the first QoS flow to indicate that the first data volume is the data volume corresponding to the first QoS flow.

[0187] Case 12:

[0188] In the case where the user plane network element caches the service data of the terminal, the session management network element may trigger the user plane network element to start the second timer.

[0189] The session management network element may also send third information to the user plane network element of the terminal based on the first information. The specific implementation is similar to the above-mentioned method 1, which can be understood by reference, but the difference is that the third information may include fourth indication information. The fourth indication information may be used to instruct the user plane network element to report the amount of cached service data of the terminal when the second timer expires. The second timer may be a timer of the user plane network element. The fourth indication information may be the same information as the first indication information, that is, the session management network element may forward the first information (including the first indication information) to the user plane network element. Alternatively, the fourth indication information may also be different information from the first indication information, that is, the session management network element may send the fourth indication information to the user plane network element based on the first indication information. For example, the session management network element may convert the first indication information into a cell format that can be recognized by the user plane network element, obtain the fourth indication information, and then send the third information carrying the fourth indication information to the user plane network element.

[0190] Optionally, the session management network element may also send the duration of the second timer to the user plane network element. The duration of the second timer may be the same as or different from the duration of the first timer. For example, considering the processing and communication delay of the session management network element, the session management network element may obtain the duration of the second timer by subtracting the processing delay of the session management network element and / or the communication delay between the session management network element and the user plane network element from the duration of the first timer. The duration of the second timer may also be carried in the third information, so as to be carried in the same information as the fourth indication information, thereby reducing the number of communications. However, this is not a limitation, and the two may also be carried in different information respectively to achieve decoupling and more flexible information element transmission. In addition, the duration of the second timer sent by the session management network element to the user plane network element is an example. For example, if the user plane network element locally pre-configures or pre-defines the duration of the second timer, the session management network element may not send the duration of the first timer to the user plane network element.

[0191] In one example, the user plane network element may set the duration of the second timer according to the received duration when receiving the duration of the second timer from the session management network element, and start the second timer when receiving the fourth indication information. In another example, the user plane network element is locally preconfigured with the duration of the second timer, and the user plane network element may start the local second timer when receiving the fourth indication information. Further, when the second timer times out, the user plane network element may send the first data volume to the session management network element. For example, the user plane network element may trigger the acquisition of the first data volume according to the timeout of the second timer, and send the first data volume to the session management network element, such as the second N4 session modification message carrying the first data volume. Optionally, the second N4 session modification message may also include the identifier of the first QoS flow, that is, indicating that the first data volume is the data volume corresponding to the first QoS flow. In this way, the session management network element may also send the first data volume to the access and mobility management network element, such as a Namf MT service message carrying the first data volume. Optionally, the Namf MT service message may also include the identifier of the first QoS flow to indicate that the first data volume is the data volume corresponding to the first QoS flow.

[0192] It can be understood that the second timer can also be configured with QoS flow as the granularity. For example, the duration of the second timer corresponds to the identifier of the first QoS flow in the third information, then the second timer is configured to the first QoS flow, such as one or more QoS flows. In this case, if the first timer corresponding to a QoS flow times out, the user plane network element can report the amount of data corresponding to the QoS flow. Alternatively, the user plane network element can also configure the second timer with QoS flow as the granularity by default.

[0193] It can also be understood that in method 2, the first data amount reported by the session management network element or the user plane network element can also be an increment or a total amount. The principle is similar to that of the above method 1, which can be understood by reference and will not be repeated here.

[0194] With respect to the above-mentioned method 3, upon receiving the second indication information, the session management network element reports the data volume of the cached service data of the terminal or triggers the user plane network element to report the data volume.

[0195] Specifically, the session management network element can determine whether to report the data volume of the service data itself or trigger the user plane network element to report the data volume of the service data according to whether the service data of the terminal is cached locally or in the user plane network element, which are introduced below.

[0196] Case 21: The session management network element caches the service data of the terminal.

[0197] The session management network element may trigger the comparison of the data volume of the terminal's cached service data with the cached data volume threshold according to the cached data volume threshold received from the access and mobility management network element. Alternatively, if the session management network element pre-configures the cached data volume threshold locally, the session management network element may trigger the comparison of the data volume of the terminal's cached service data with the cached data volume threshold according to the received second indication information. Moreover, after the triggering, the session management network element may also periodically compare the data volume of the terminal's cached service data with the cached data volume threshold, or may also compare the data volume of the latest terminal's cached service data with the cached data volume threshold when the terminal's cached service data is updated. If the data volume of the terminal's cached service data is less than the cached data volume threshold, the session management network element does not report the data volume of the terminal's cached service data. If the data volume of the terminal's cached service data is the first data volume, that is, it reaches (such as greater than or equal to) the cached data volume threshold, the session management network element may send the first data volume to the access and mobility management network element, such as a Namf_MT service message carrying the first data volume. Optionally, the Namf MT service message may also carry the identifier of the first QoS flow, and the first data volume is the data volume corresponding to the first QoS flow.

[0198] It can be understood that since the cache data volume threshold can be configured with QoS flow as the granularity, and the cache data volume threshold corresponding to each QoS flow can also be different, the session management network element can decouple or asynchronously report the data volume corresponding to these QoS flows. For example, if the data volume corresponding to a QoS flow exceeds the cache data volume threshold corresponding to the QoS flow, the session management network element can report the data volume corresponding to the QoS flow, while for the QoS flow that does not exceed the cache data volume threshold, the session management network element will not report the data volume corresponding to the QoS flow.

[0199] Case 22: The user plane network element caches the service data of the terminal.

[0200] The session management network element may also send third information to the user plane network element of the terminal based on the first information. The specific implementation is similar to the above-mentioned method 1, which can be understood by reference, but the difference is that the third information may include fifth indication information, and the fifth indication information may be used to instruct the user plane network element to report the data volume of the cached service data of the terminal when the data volume of the cached service data of the terminal reaches the cached data volume threshold. The fifth indication information and the second indication information may be the same information, that is, the session management network element may forward the first information (including the second indication information) to the user plane network element. Alternatively, the fifth indication information and the second indication information may also be different information, that is, the session management network element may send the fifth indication information to the user plane network element based on the second indication information. For example, the session management network element may convert the second indication information into a cell format that can be recognized by the user plane network element, obtain the fifth indication information, and then send the third information carrying the fifth indication information to the user plane network element.

[0201] Optionally, the session management network element may also send a cache data volume threshold to the user plane network element. The cache data volume threshold may also be carried in the third information, so as to be carried in the same information as the fifth indication information, thereby reducing communication overhead. However, this is not a limitation, and the two may also be carried in different information, respectively, to achieve decoupling, and more flexible information element transmission. In addition, the session management network element sending the cache data volume threshold to the user plane network element is an example. For example, if the user plane network element is locally pre-configured or pre-defined with a cache data volume threshold, the session management network element may not send the cache data volume threshold to the user plane network element.

[0202] It can be understood that for the user plane network element, the cache data volume threshold can also be configured with QoS flow as the granularity. For example, the cache data volume threshold corresponds to the identifier of the first QoS flow in the third information, then the cache data volume threshold is configured to one or more first QoS flows. In this case, if the data volume corresponding to a QoS flow exceeds the cache data volume threshold corresponding to the QoS flow, the user plane network element reports the data volume corresponding to the QoS flow. Alternatively, the user plane network element may also default to the cache data volume threshold with QoS flow as the granularity. In addition, the value of the user plane threshold corresponding to each QoS flow may be the same, or may be different.

[0203] The user plane network element may trigger the comparison of the data volume of the terminal's cached service data with the cached data volume threshold according to the cached data volume threshold received from the session management network element. Alternatively, if the user plane network element pre-configures the cached data volume threshold locally, the user plane network element may trigger the comparison of the data volume of the terminal's cached service data with the cached data volume threshold according to the received fifth indication information. Moreover, after the trigger, the user plane network element may also periodically compare the data volume of the terminal's cached service data with the cached data volume threshold, or may also compare the data volume of the latest terminal's cached service data with the cached data volume threshold when the terminal's cached service data is updated. If the data volume of the terminal's cached service data is less than the cached data volume threshold, the user plane network element does not report the data volume of the terminal's cached service data. If the data volume of the terminal's cached service data is the first data volume, that is, it reaches (such as greater than or equal to) the cached data volume threshold, the user plane network element may send the first data volume to the session management network element, such as a second N4 session modification message carrying the first data volume. Optionally, the second N4 session modification message may also include an identifier of the first QoS flow, that is, indicating that the first data volume is the data volume corresponding to the first QoS flow. In this way, the session management network element may also send the first data volume to the access and mobility management network element, such as a Namf service message carrying the first data volume. Optionally, the Namf MT service message may also include an identifier of the first QoS flow, indicating that the first data volume is the data volume corresponding to the first QoS flow.

[0204] It can be understood that since the cache data volume threshold can be configured with QoS flow as the granularity, and the cache data volume threshold corresponding to each QoS flow can also be different, the user-plane network element can decouple or asynchronously report the data volume corresponding to these QoS flows. For example, if the data volume corresponding to a QoS flow exceeds the cache data volume threshold corresponding to the QoS flow, the user-plane network element can report the data volume corresponding to the QoS flow, while for the QoS flow that does not exceed the cache data volume threshold, the user-plane network element will not report the data volume corresponding to the QoS flow.

[0205] With respect to the above-mentioned mode 4, when the session management network element receives the third indication information, it reports the data volume of the cached service data of the terminal or triggers the user plane network element to report the data volume.

[0206] Specifically, the session management network element may choose to report the data volume itself or have the user plane network element report the data volume according to whether the service data of the terminal is cached locally or in the user plane network element, which are introduced below.

[0207] Case 31: The session management network element caches the terminal's cached service data.

[0208] The session management network element may trigger, according to the third indication information, to report the data volume of the terminal's service data each time the service data of the terminal is received. The session management network element may determine whether the current reception is completed according to the continuity of the received data packets. If the reception is completed, the data volume of the terminal's service data is received this time. Otherwise, the reception continues to be waited for until the reception is completed. For example, if the time interval between the data packets of each two adjacent data received by the session management network element is less than the time interval threshold, the two adjacent data packets are considered to be received continuously. On this basis, the session management network element determines that N data packets are received continuously, where N is an integer greater than 1. If the session management network element waits for more than the time interval threshold after receiving the Nth data and does not receive a new data packet, the session management network element determines that the current reception is completed. In the case of the current reception completion, the session management network element may send the data volume received this time to the access and mobility management network element, and optionally, also includes a first QoS flow identifier to indicate that the data volume received this time is the data volume corresponding to the first QoS flow. Before the state of the terminal changes to the reachable state, the session management network element may report the data volume at least once, and the first data volume may be the total amount of data reported at least once.

[0209] It can be understood that the session management network element can report at the QoS flow granularity. For example, the session management network element determines which QoS flows among one or more first QoS flows the data received this time corresponds to, and then reports the data volume corresponding to these QoS flows. For the QoS flow that did not receive data this time, the session management network element does not report the data volume corresponding to the QoS flow.

[0210] Case 32: The user plane network element caches the service data of the terminal.

[0211] The session management network element may also send third information to the user plane network element corresponding to the terminal based on the first information. The specific implementation is similar to the above-mentioned method 1, which can be understood by reference, but the difference is that the third information may include sixth indication information. The sixth indication information may be used to indicate that the user plane network element reports the data volume of the terminal's service data each time the service data of the terminal is received when the terminal is in an inactive and unreachable state. Among them, the sixth indication information and the third indication information may be the same information, that is, the session management network element may forward the first information (including the third indication information) to the user plane network element. Alternatively, the sixth indication information and the third indication information may also be different information, that is, the session management network element may send the sixth indication information to the user plane network element based on the third indication information. For example, the session management network element may convert the third indication information into a cell format that can be recognized by the user plane network element, obtain the sixth indication information, and then send the third information carrying the sixth indication information to the user plane network element.

[0212] The user plane network element can trigger the reporting of the data volume of the terminal's service data each time the terminal's buffered service data is received according to the sixth indication information received from the session management network element. Among them, the user plane network element can also determine whether the current reception is completed according to the continuity of the received data packets. The specific implementation is similar to the above-mentioned session management network element, which can be understood by reference. In the case of the completion of this reception, the user plane network element sends the data volume of the terminal's service data received this time to the session management network element, such as a data arrival notification message carrying the data volume. Optionally, the data arrival notification message can also include a first QoS flow identifier to indicate that the data volume received this time is the data volume corresponding to the first QoS flow. Correspondingly, the session management network element can continue to report the data volume received by the user plane network element this time to the access and mobility management network element, such as an MT request message carrying the data volume. Optionally, the MT request message can also carry a first QoS flow identifier to indicate that the data volume received this time is the data volume corresponding to the first QoS flow. Similarly, before the state of the terminal changes to a reachable state, the user plane network element and the session management network element can report the data volume at least once, and the first data volume can be the total amount of data reported at least once.

[0213] It can be understood that the user-plane network element can also report at the QoS flow granularity. For example, the user-plane network element determines which QoS flows among one or more first QoS flows the data received this time corresponds to, and then reports the data volume corresponding to these QoS flows. For the QoS flow that did not receive data this time, the user-plane network element does not report the data volume corresponding to the QoS flow.

[0214] It can also be understood that the session management network element can report the amount of data received for the first time through the MT process, such as the MT request message. Afterwards, the session management network element can still report the amount of data received thereafter through the MT process, such as the MT request message, or other messages, such as the Namf service message, without specific limitation.

[0215] It can also be understood that the session management network element can obtain whether the service data of the terminal is cached locally or in the user-plane network element through pre-configuration or protocol pre-determined manner, and the specific implementation method is not limited.

[0216] S303: The access and mobility management network element sends a second data volume to an access network device of the terminal according to the first data volume.

[0217] The second data volume may be the same as or different from the first data volume, which will be introduced below.

[0218] In one possible manner, the second data volume is different from the first data volume. For example, when the first QoS flow includes a QoS flow supporting SDT DRB and a QoS flow not supporting SDT DRB, the first data packet includes the data volume corresponding to the first QoS flow, and the second data volume may be the data volume corresponding to the QoS flow supporting SDT DRB in the first QoS flow. It can be understood that the access and mobility management network element sends the data volume corresponding to the QoS flow supporting SDT DRB to the access network device based on the first data volume to avoid communication redundancy.

[0219] In another possible manner, the second data volume is the same as the first data volume. For example, in the case where the first QoS flow includes a QoS flow that supports SDT DRB and a QoS flow that does not support SDT DRB, the access and mobility management network element can directly send the first data volume to the access network device. Furthermore, the access network device not only considers the data volume corresponding to the QoS flow that supports SDT DRB, but also considers the data volume corresponding to the QoS flow that does not support SDT DRB when executing the MT SDT decision. For another example, in the case where the first QoS flow is a QoS flow that supports SDT DRB, the access and mobility management network element can directly send the first data volume to the access network device.

[0220] Optionally, no matter whether the first data volume or the second data volume is reported, the access and mobility management network element may also report the identifier of the corresponding QoS flow to indicate that these data volumes are the data volumes corresponding to these QoS flows respectively.

[0221] It can be understood that the implementation of S303 is an example, but not a limitation. For example, when the second data volume is different from the first data volume, the user plane network element can send the second data volume to the session management network element according to the first data volume, or the session management network element can also send the second data volume to the access and mobility management network element according to the first data volume. In this way, the access and mobility management network element can also directly send the second data volume to the access network device.

[0222] In summary, the access and mobility management network element can actively instruct the session management network element to report the data volume of service data, such as the first data volume of service data cached by the network when the terminal is in an inactive state, so that the access and mobility management network element can inform the access network device of the corresponding data volume, such as the second data volume, so that the access network device can make a more accurate MT SDT decision.

[0223] Optionally, in combination with the above method, before S301, the method may further include:

[0224] S300: An access and mobility management network element receives second information from an access network device.

[0225] The second information may be carried in an N2 message or any other possible message. The second information may include information about the first QoS flow, so that the access and mobility management network element may send the first information to the session management network element according to the information about the first QoS flow. The information about the first QoS flow may include at least one of the following: an identifier of the first QoS flow, a PDU session identifier, SDT indication information, SDT enabling information, or a data volume threshold of an SDT DRB.

[0226] The identifier of the first QoS flow can be used to indicate the first QoS flow. Further, the access and mobility management network element can send the first information carrying the identifier of the first QoS flow to the session management network element based on the identifier of the first QoS flow in the information of the first QoS flow.

[0227] It can be understood that when the second information does not include the identifier of the first QoS flow, the access and mobility management network element can obtain and report the data volume of cached service data corresponding to all QoS flows of the terminal or the cached data volume corresponding to all QoS flows that have cached downlink data or have downlink data arriving by default.

[0228] It can be understood that the access and mobility management network element can obtain and report the data volume of cached service data corresponding to which QoS flows of the terminal according to the protocol pre-definition, or it can negotiate in advance with the access and mobility management network element and the access network equipment to report the data volume of cached service data corresponding to which QoS flows of the terminal. Furthermore, after receiving the second information, the access and mobility management network element reports the data volume of cached service data corresponding to these QoS flows by default.

[0229] The PDU session identifier can be used to identify the PDU session corresponding to the first QoS flow, so that the access and mobility management network element can determine the session management network element corresponding to the PDU session, so as to be able to send the first information to the session management network element. It can be understood that the PDU session identifier can also be an optional information element in the first QoS flow information, for example, the access and mobility management network element does not need the indication of the PDU session identifier, and sends the first information to the session management network element by default.

[0230] The SDT indication information can be used to indicate which QoS flows in the first QoS flow have corresponding DRBs configured with SDT DRBs, so that the access and mobility management network element decides whether to report only the amount of cached service data corresponding to these QoS flows that support SDT DRBs. For example, the SDT indication information corresponds to the identifiers of the QoS flows that support SDT DRBs in the first QoS flow, to indicate that these corresponding QoS flows support SDT DRBs. It can be understood that the SDT indication information is an optional element in the first QoS flow information, and the QoS flows that support SDT DRBs can also be implicitly indicated in other ways. For example, the first QoS flow contains 5 QoS flows, and by default, the xth to yth QoS flows in the identifier list composed of the identifiers of these 5 QoS flows support SDT DRBs.

[0231] The SDT enabling information may be used to indicate the amount of cached service data of the terminal reported by the access and mobility management network element. For example, the information element of the SDT enabling information may indicate that the terminal currently in an inactive state is configured with an SDT DRB, so as to implicitly indicate the amount of cached service data of the terminal reported by the access and mobility management network element by indicating the configuration of the SDT DRB. Alternatively, the information element of the SDT enabling information may also indicate the amount of cached service data of the terminal reported by the access and mobility management network element.

[0232] That is, the SDT enabling information is information with a coarser indication granularity than the SDT indication information. If the second information carries the SDT enabling information, it indicates that the access and mobility management network element reports the data volume of the cached service data of the terminal, without distinguishing whether the QoS flow supports SDT DRB. However, if the second information carries the SDT indication information, it indicates that the access and mobility management network element can only report the data volume corresponding to the QoS flow supporting SDT DRB in the cached service data of the terminal.

[0233] The data volume threshold of the SDT DRB can be used to indicate the data volume threshold, or the upper limit of the data volume that the SDT DRB of the access network device can carry, so as to allow the access and mobility management network element to decide whether to report the data volume to the access and mobility management network element. For example, when the first QoS flow supports the SDT DRB, the access and mobility management network element obtains the data volume of the network cached data reported by the session management network element through the MT process, such as the third data volume mentioned above. At this time, the access and mobility management network element can determine whether the third data volume is less than the data volume threshold. If the third data volume is less than the data volume threshold, the access and mobility management network element sends the first information to the session management network element, that is, when the data volume of the network cached data is less than the upper limit of the data volume that the SDT DRB can carry, the access and mobility management network element allows the network to continue to cache and report the data volume, otherwise, the access network device is triggered to restore the terminal to the connected state.

[0234] Optionally, the data volume threshold of the SDT DRB may be the same for the QoS flow corresponding to each SDT DRB, or may be different, and there is no limitation on this.

[0235] Combination of the above Figure 3 The overall process of the communication method provided in the embodiment of the present application is introduced below. Figure 4-Figure 7 This section describes the specific process of this communication method in various scenarios.

[0236] Figure 4 Schematic diagram of the communication method provided in the embodiment of the present application Figure 2 The communication method is applicable to the above communication system, and mainly involves the interaction between RAN equipment (such as the above access network equipment), AMF network element (such as the above access and mobility management network element), SMF network element (such as the above session management network element), and UPF network element (such as the above user plane network element). In this scenario, the AMF network element can instruct the SMF network element to report the amount of cached service data of the UE when the UE is about to be reachable.

[0237] like Figure 4 As shown, the process of the communication method is as follows:

[0238] S401, the RAN device releases the UE to an inactive state and configures eDRX parameters in the inactive state.

[0239] The eDRX parameter may be a long eDRX parameter, i.e., the eDRX cycle is greater than 10.24s, which is used to indicate when the UE sleeps and / or when it can be awakened in an inactive state. Optionally, the RAN device may also configure SDT DRB / SRB for certain DRB / SRBs, i.e., the RAN device specifies which DRB / SRB data can enable SDT for transmission. In addition, the RAN device specifically selects which DRB / SRB to configure SDT DRB / SRB, which is not limited in the embodiments of the present application, and the RAN device may select according to its own resource usage.

[0240] S402, the RAN device sends an N2 message to the AMF network element.

[0241] The N2 message may include an eDRX parameter, which is an eDRX parameter used by the UE to enter the RRC inactive state;

[0242] Optionally, information about the first QoS flow may also be included (refer to the relevant introduction of S300). That is, after the UE is released to the inactive state, the RAN device may send the eDRX parameters in the inactive state and the information about the first QoS flow to the AMF network element, so that the AMF network element can perform reachability detection on the UE and report the data volume corresponding to the first QoS flow cached by the network.

[0243] Optionally, SDT enabling information may also be included to indicate that the terminal device currently in the deactivated state is configured with SDT radio bearer resources, or to indicate that the access and mobility management network provides the amount of service data cached by the terminal device in the deactivated state in an unreachable state. The provision of the cached data volume is provided at the granularity of the QoS flow.

[0244] S403, the AMF network element sends a PDU session management service context update (Nsmf_PDUSession_update SMContext) message to the SMF network element.

[0245] S404, the SMF network element modifies the N4 session and caches it.

[0246] S405, the SMF network element sends the N1N2 message transfer service (Namf_Communication_N1N2Message Transfer service) to the AMF network element.

[0247] S406, the UE's service data arrives at the UPF network element.

[0248] The service data of the UE may be data corresponding to the first QoS flow, or data to be carried by the first QoS flow. For the introduction of the first QoS flow, reference may be made to the relevant introduction of S301 above, which will not be repeated here.

[0249] S407, the UPF network element sends a data notification message to the SMF network element.

[0250] The data notification message may carry the data volume of the service data of the UE, such as the third data volume mentioned above.

[0251] S408, the SMF network element sends an MT enable UE reachability request message to the AMF network element.

[0252] The MT-enabled UE reachability request message may include a third data volume, an identifier of the first QoS flow, and an identifier of the PDU session where the first QoS flow is located, so as to enable the AMF network element to query the reachability of the UE.

[0253] S409, the AMF network element determines that the UE is in an unreachable state.

[0254] The AMF network element may query the corresponding UE according to the identifier of the first QoS flow and the identifier of the PDU session in which the first QoS flow is located. The AMF network element may query the reachability of the UE according to the eDRX parameters of the UE and determine that the UE is in an unreachable state.

[0255] S410, the AMF network element sends a MT enable UE reachability response (Namf_MT_EnableUERechabilityresponse) message to the SMF network element.

[0256] When the UE is in an unreachable state, the MT enables the UE to be reachable response message to instruct the AMF network element to reject the request of the SMF network element.

[0257] For example, the MT-enabled UE reachable response message may include a rejection indication, indicating that the reason why the AMF network element rejects the SMF network element is that the UE is in an unreachable state. The MT-enabled UE reachable response message may also include a maximum waiting delay, which may be determined by the AMF network element based on the eDRX parameters of the UE to indicate how long the UE may be reachable. The SMF network element may determine to cache previously received downlink data based on the maximum waiting delay. For example, the SMF network element may instruct the UPF network element to cache the downlink data, or may instruct the UPF network element to send the downlink data to the SMF network element for cache by the SMF network element.

[0258] Optionally, if the first QoS flow supports SDT DRB, the AMF network element can also determine whether the third data volume is less than the data volume threshold of SDT DRB. The data volume threshold of SDT DRB can be obtained by the AMF network element from the information of the first QoS flow, or the AMF network element can also be obtained from other network elements, such as UDM network elements, or can also be configured locally in the AMF network element. If the third data volume is less than the data volume threshold of SDT DRB, the AMF network element sends an MT-enabled UE reachable response message to the SMF network element, otherwise, the AMF network element can trigger the RAN device to restore the UE to the connected state. The specific implementation can also refer to the relevant introduction of S300 above, which will not be repeated here.

[0259] S411, when the UE state changes to a reachable state, the AMF network element triggers a query on the UE's service data cached in the network.

[0260] The change of the UE's state to the reachable state can be understood as the UE's state is about to change to the reachable state. For example, the AMF network element determines that the UE is about to be reachable based on the UE's eDRX parameters, that is, the AMF network element is about to trigger the RAN device to page the UE, and the AMF network element determines to query the network cache for the UE's service data. At this time, the AMF network element can determine the SMF network element corresponding to the PDU session based on the PDU session identifier in the information of the first QoS flow, and determine to query these SMF network elements for the UE's service data cached in the network, and execute S412.

[0261] For example, the PDU session identifier includes: PDU session #1, PDU session #2 and PDU session #3, PDU session #1 corresponds to SMF network element #1, PDU session #2 and PDU session #3 correspond to SMF network element #2, and the AMF network element determines to query the UE service data cached in the network from SMF network element #1 and SMF network element #2 respectively.

[0262] Optionally, if the information of the first QoS flow includes SDT indication information, the AMF network element may also select to query the data volume corresponding to the QoS flow supporting SDT DRB in the first QoS flow according to the SDT indication information, and execute S412. Alternatively, the AMF network element may not select and still query the data volume corresponding to the first QoS flow.

[0263] For ease of understanding, the following takes the AMF network element querying the data volume corresponding to the first QoS flow as an example.

[0264] S412, the AMF network element sends a service management context acquisition request (Nsmf_SMContextrequest) message to the SMF network element.

[0265] The AMF network element may send a service management context acquisition request message to the SMF network element when the UE is about to be reachable, or the AMF network element is about to trigger the RAN device to page the UE. The service management context acquisition request message may include first information for triggering the SMF network element to report the amount of cached service data of the UE, such as the amount of data corresponding to the first QoS flow. The specific implementation may also refer to the relevant introduction of method 1 in S301 above, which will not be repeated here.

[0266] S413, the SMF network element obtains the first data volume of the UE's cached service data locally.

[0267] If the UE's service data is cached by the SMF network element, the SMF network element executes S413.

[0268] S414, the SMF network element sends the first N4 session modification (N4_Session modification) message to the UPF network element.

[0269] The first N4 session modification message may include third information used to trigger the UPF network element to report the amount of cached service data of the UE.

[0270] S415, the UPF network element sends a second N4 session modification message to the SMF network element.

[0271] The second N4 session modification message may include a first data volume of the UE's cached service data.

[0272] S416, the SMF network element sends a service management context acquisition response (Nsmf_SMContextresponse) message to the AMF network element.

[0273] The service management context acquisition response message may include a first amount of data.

[0274] It can be understood that the specific implementation of S413-S416 can also refer to the relevant introduction of method 1 in the above S302, which will not be repeated here.

[0275] S417, the AMF network element sends a downlink data notification (DL data notification) message to the RAN device.

[0276] The downlink data notification message may include a second data amount, and the second data amount may be the same as or different from the first data amount. For specific implementation, reference may be made to the relevant introduction of S303 above, which will not be repeated here.

[0277] Figure 5 Schematic diagram of the communication method provided in the embodiment of the present application Figure 3 The communication method is applicable to the above communication system, and mainly involves the interaction between RAN equipment (such as the above access network equipment), AMF network element (such as the above access and mobility management network element), SMF network element (such as the above session management network element), and UPF network element (such as the above user plane network element). In this scenario, the AMF network element can trigger the SMF network element / UPF network element to start a timer so that when the timer expires, such as when the UE is about to be reachable, the data volume of the UE's cached service data is reported.

[0278] like Figure 5 As shown, the process of the communication method is as follows:

[0279] S501, the RAN device releases the UE to an inactive state and configures eDRX parameters in the inactive state.

[0280] S502, the RAN device sends an N2 message to the AMF network element.

[0281] Among them, S501-S502 can refer to the relevant introduction of S401-S402 above, which will not be repeated here.

[0282] S503, the AMF network element sends a PDU session context update message to the SMF network element.

[0283] Optionally, the PDU session context update message may carry the first information. The first information may include the first indication information, which is used to indicate the SMF network element to report the amount of service data of the UE when the first timer times out. Optionally, it may also include the duration of the first timer, which may cause the first timer to time out when the UE is about to be reachable. The specific implementation may also refer to the relevant introduction of the method 2 in the above S301, which will not be repeated here. Optionally, the duration of the first timer may reuse the maximum waiting delay.

[0284] S504, the SMF network element sends the third information to the UPF network element.

[0285] Optionally, the third information may include fourth indication information, used to instruct the UPF network element to report the amount of service data of the UE when the second timer expires. Optionally, the third information may also include the duration of the second timer, which may cause the second timer to time out when the UE is about to be reachable. The specific implementation may also refer to the relevant introduction of method 2 in S302 above, which will not be repeated here.

[0286] It can be understood that S504 is an optional step. If the UE's service data is cached by the UPF network element, the SMF network element executes S504, otherwise, S504 is not executed.

[0287] S505, the SMF network element modifies the N4 session and caches it.

[0288] S506, the SMF network element sends N1N2 message transmission service to the AMF network element.

[0289] S507, the UE's service data arrives at the UPF network element.

[0290] S508, the UPF network element sends a data notification message to the SMF network element.

[0291] S509, the SMF network element sends an MT enable UE reachability request message to the AMF network element.

[0292] S510, the AMF network element determines that the UE is in an unreachable state.

[0293] Among them, S507-S510 can refer to the relevant introduction of S404-S409 above, which will not be repeated here.

[0294] S511, the AMF network element sends an MT-enabled UE reachable response message to the SMF network element.

[0295] The MT-enabled UE reachable response message may carry the information described in S410. In the case where the PDU session context update message of S503 does not carry the first information, the MT-enabled UE reachable response message may also carry the first information. In this case, S504 may be executed after S511. That is, executing S504 after executing S503 and executing S504 after executing S511 may be parallel optional implementations.

[0296] It can also be understood that the specific implementation of S511 can also refer to the relevant introduction of method 2 in the above S302, which will not be repeated here.

[0297] S512, the SMF network element obtains a first data volume of cached service data of the UE according to the expiration of the first timer.

[0298] The SMF network element can obtain the first data volume of the UE's cached service data locally, or it can obtain the first data volume of the UE's cached service data from the UPF network element.

[0299] S513: The UPF network element obtains the first data volume of the UE's cached service data from the local according to the expiration of the second timer.

[0300] S514, the AMF network element sends the first amount of data to the SMF network element.

[0301] S515, the SMF network element sends the first amount of data to the AMF network element.

[0302] It can be understood that S512 and S515 are in an "or" execution relationship with S513-S515. The specific implementation of S512-S515 can also refer to the relevant introduction of the method 2 in the above S302, which will not be repeated here.

[0303] S516, the AMF network element sends a downlink data notification message to the RAN device.

[0304] The downlink data notification message may include the second data volume. For specific implementation, reference may be made to the related introduction of S303 above, which will not be described in detail here.

[0305] Figure 6 Schematic diagram of the communication method provided in the embodiment of the present application Figure 4. The communication method is applicable to the above-mentioned communication system, and mainly involves the interaction between RAN equipment (such as the above-mentioned access network equipment), AMF network elements (such as the above-mentioned access and mobility management network elements), SMF network elements (such as the above-mentioned session management network elements), and UPF network elements (such as the above-mentioned user plane network elements). In this scenario, the AMF network element sends the cache data volume threshold to the SMF network element / UPF network element, so that the amount of cached service data of the SMF network element / UPF network element UE reaches the cache data volume threshold and reports the data volume.

[0306] like Figure 6 As shown, the process of the communication method is as follows:

[0307] S601: The RAN device releases the UE to an inactive state and configures eDRX parameters in the inactive state.

[0308] S602, the RAN device sends an N2 message to the AMF network element.

[0309] Among them, S601-S602 can refer to the relevant introduction of S401-S402 above, which will not be repeated here.

[0310] S603, the AMF network element sends a PDU session context update message to the SMF network element.

[0311] The PDU session context update message may carry the first information. The first information may include second indication information, which is used to instruct the SMF network element to report the data volume of the UE's cached service data when the data volume of the UE's cached service data reaches the cached data volume threshold. Optionally, the cached data volume threshold may also be included. The specific implementation may also refer to the relevant introduction of the above-mentioned method 3 in S301, which will not be repeated here.

[0312] S604, the SMF network element sends the third information to the UPF network element.

[0313] The third information may include fifth indication information, used to instruct the UPF network element to report the data volume of the UE's cached service data when the data volume of the UE's cached service data reaches the cached data volume threshold. Optionally, the third information may also include the cached data volume threshold. The specific implementation may also refer to the relevant introduction of method 3 in the above S302, which will not be repeated here.

[0314] It can be understood that S604 is an optional step. If the UE's service data is cached by the UPF network element, the SMF network element executes S604, otherwise, S604 is not executed.

[0315] S605, the SMF network element modifies the N4 session and caches it.

[0316] S606, the SMF network element sends N1N2 message transmission service to the AMF network element.

[0317] S607, the UE's service data arrives at the UPF network element.

[0318] S608, the UPF network element sends a data notification message to the SMF network element.

[0319] S609, the SMF network element sends an MT enable UE reachability request message to the AMF network element.

[0320] S610, the AMF network element determines that the UE is in an unreachable state.

[0321] Among them, S607-S610 can refer to the relevant introduction of S404-S409 above, which will not be repeated here.

[0322] S611, the AMF network element sends an MT-enabled UE reachable response message to the SMF network element.

[0323] The MT-enabled UE reachable response message may carry the information described in S410. In the case where the PDU session context update message of S603 does not carry the first information, the MT-enabled UE reachable response message may also carry the first information. In this case, S604 may be executed after S611. That is, executing 604 after executing S603 and executing 604 after executing S611 may be parallel optional implementations.

[0324] It can be understood that the specific implementation of S611 can also refer to the relevant introduction of method 3 in the above S302, which will not be repeated here.

[0325] S612, the SMF network element obtains the first data volume of the UE's cached service data from the local according to the data volume of the UE's cached service data reaching the cached data volume threshold.

[0326] S613, the UPF network element obtains the first data volume of the UE's cached service data from the local according to the data volume of the UE's cached service data reaching the cached data volume threshold.

[0327] S614, the AMF network element sends the first amount of data to the SMF network element.

[0328] S615, the SMF network element sends the first amount of data to the AMF network element.

[0329] It can be understood that S612 and S615 are in an "or" execution relationship with S613-S615. The specific implementation of S612-S615 can also refer to the relevant introduction of the method 3 in the above S302, which will not be repeated here.

[0330] S616, the AMF network element sends a downlink data notification message to the RAN device.

[0331] The downlink data notification message may include the second data volume. For specific implementation, reference may be made to the related introduction of S303 above, which will not be described in detail here.

[0332] Figure 7 Schematic diagram of the communication method provided in the embodiment of the present application Figure 5 The communication method is applicable to the above communication system, and mainly involves the interaction between RAN equipment (such as the above access network equipment), AMF network element (such as the above access and mobility management network element), SMF network element (such as the above session management network element), and UPF network element (such as the above user plane network element). In this scenario, the AMF network element can instruct the SMF network element / UPF network element to report the corresponding data volume each time it receives and caches the service data of the UE.

[0333] like Figure 7 As shown, the process of the communication method is as follows:

[0334] S701: The RAN device releases the UE to an inactive state and configures eDRX parameters in the inactive state.

[0335] S702, the RAN device sends an N2 message to the AMF network element.

[0336] Among them, S701-S702 can refer to the relevant introduction of S401-S402 above, which will not be repeated here.

[0337] S703, the AMF network element sends a PDU session context update message to the SMF network element.

[0338] The PDU session context update message may carry the first information. The first information may include third indication information, which is used to indicate that when the terminal is in an inactive and unreachable state, the SMF network element reports the data volume of the UE's service data each time the network receives the UE's service data. The specific implementation may also refer to the relevant introduction of the method 4 in the above S301, which will not be repeated here.

[0339] S704, the SMF network element sends the third information to the UPF network element.

[0340] The third information may include sixth indication information, which is used to instruct the UPF network element to report the amount of UE's service data each time the network receives service data from the UE when the terminal is in an inactive and unreachable state. The specific implementation can also refer to the relevant introduction of method 4 in the above S302, which will not be repeated here.

[0341] It can be understood that S704 is an optional step. If the UE's service data is cached by the UPF network element, the SMF network element executes S704, otherwise, S704 is not executed.

[0342] S705, the SMF network element modifies the N4 session and caches it.

[0343] S706, the SMF network element sends N1N2 message transmission service to the AMF network element.

[0344] S707, the UE's service data arrives at the UPF network element.

[0345] S708, UPF network element sends data notification message to SMF network element.

[0346] S709, the SMF network element sends an MT enable UE reachability request message to the AMF network element.

[0347] S710, the AMF network element determines that the UE is in an unreachable state.

[0348] Among them, S707-S710 can refer to the relevant introduction of S404-S409 above, which will not be repeated here.

[0349] S711, the AMF network element sends an MT-enabled UE reachable response message to the SMF network element.

[0350] The MT-enabled UE reachable response message may carry the information described in S410. In the case where the PDU session context update message of S603 does not carry the first information, the MT-enabled UE reachable response message may also carry the first information. In this case, S604 may be executed after S611. That is, executing S704 after executing S703 and executing S704 after executing S711 may be parallel optional implementations.

[0351] It can be understood that the specific implementation of S611 can also refer to the relevant introduction of method 4 in the above S302, which will not be repeated here.

[0352] S712, the SMF network element obtains the amount of service data of the UE received by the network this time.

[0353] S713, the UPF network element obtains the amount of UE service data received by the network this time.

[0354] S714, the AMF network element sends the amount of UE's service data received by the network this time to the SMF network element.

[0355] S715, the SMF network element sends the amount of UE service data received by the network this time to the AMF network element.

[0356] It can be understood that S712 and S715 are in an "or" execution relationship with S713-S715. The specific implementation of S712-S715 can also refer to the relevant introduction of the above-mentioned mode 4 in S302, which will not be repeated here.

[0357] It can also be understood that S707-S715 can be repeated multiple times to report the amount of service data of the UE received by the network each time. Alternatively, only S707, S712-S715 can be repeated. If the AMF network element sends the first information to the SMF network element through S703, the subsequent execution of S707-S715 can be considered as the first data volume reported by the UPF network element / SMF network element. If the AMF network element sends the first information to the SMF network element through S711, the subsequent repetition of S707-S715 or S707, S712-S715 can be considered as the first data volume reported by the UPF network element / SMF network element.

[0358] S716, the AMF network element sends a downlink data notification message to the RAN device.

[0359] The downlink data notification message may include the second data volume. For specific implementation, reference may be made to the related introduction of S303 above, which will not be described in detail here.

[0360] Figure 8 Schematic diagram of the communication method provided in the embodiment of the present application Figure 5 The communication method is applicable to the above communication system, and mainly involves the interaction between access and mobility management network elements and terminals.

[0361] like Figure 8 As shown, the process of the communication method is as follows:

[0362] S801: An access and mobility management network element receives a signaling to be sent to a terminal in an unreachable state.

[0363] Among them, the signaling can be other network elements in the network, such as data management network elements (UDM / UDR network elements), session management network elements (SMF network elements), etc., which are sent to the terminal through the access and mobility management network element. The specific signaling type is not limited in the embodiments of the present application. At this time, when the access and mobility management network element receives the signaling, the terminal is in an unreachable state in an inactive state. How the access and mobility management network element determines that the terminal is in an unreachable state in an inactive state can be referred to the relevant introduction of the above embodiments, and will not be repeated here.

[0364] S802: The access and mobility management network element sends signaling related information to the access network device of the terminal.

[0365] Among them, the relevant information of the signaling can be used by the access network device to determine whether the small data transmission SDT is used to transmit the signaling. For example, the relevant information of the signaling includes the data volume of the signaling. When the state of the terminal changes to a reachable state, for example, the access and mobility management network element can determine that the state of the terminal changes to a reachable state based on the eDRX parameters of the terminal, so that the element sends the relevant information of the signaling to the access network device. That is, the access and mobility management network element can send the data volume of the signaling to be sent to the terminal by the network in the entire unreachable state of the terminal to the access network device, so as to improve the accuracy of the MT SDT judgment.

[0366] In summary, when receiving signaling to be sent to a terminal in an unreachable state, the access and mobility management network element can inform the access network device of relevant information (such as data volume) of the signaling so that the access network device can make a more accurate MT SDT decision.

[0367] Combination of the above Figure 3-Figure 8 The communication method provided by the embodiment of the present application is described in detail. Figure 9-10 A communication device for executing the communication method provided in an embodiment of the present application is described in detail.

[0368] Fig. 9 This is a schematic diagram of the structure of the communication device provided in the embodiment of the present application. Figure 1 For example, Fig. 9 As shown, the communication device 900 includes: a transceiver module 901 and a processing module 902. For ease of description, Fig. 9 Only the main components of the communication device are shown.

[0369] In some embodiments, the communication device 900 may be Figure 3 or Figure 8 The access and mobility management network element in the method shown, or Figures 5 to 7 AMF network element in the method shown.

[0370] Among them, the transceiver module 901 is used to implement the transceiver function of the access and mobility management network element or AMF network element in the above method, such as executing S302, and the processing module 902 is used to implement other functions of the access and mobility management network element or AMF network element in the above method except the transceiver function, such as executing S301.

[0371] Optionally, the transceiver module 901 may include a sending module ( Fig. 9 ) and a receiving module ( Fig. 9 The sending module is used to implement the sending function of the communication device 900, and the receiving module is used to implement the receiving function of the communication device 900.

[0372] Optionally, the communication device 900 may further include a storage module ( Fig. 9 When the processing module 902 executes the program or instruction, the communication device 900 can execute the above method. Figure 3-Figure 8 The functions of a network device (such as an access and mobility management network element or AMF network element) in the method shown.

[0373] It can be understood that the communication device 900 can be a network device, such as an access and mobility management network element or an AMF network element, or a chip (system) or other parts or components that can be set in the network device, or a device that includes a network device, which is not limited in this application.

[0374] In addition, the technical effects of the communication device 900 can be referred to Figure 3-Figure 8 The technical effects of the communication method shown will not be repeated here.

[0375] In some other embodiments, the communication device 900 may be Figure 3 The session management network element in the method shown, or Figures 5 to 7 SMF network element in the method shown.

[0376] Among them, the transceiver module 901 is used to implement the transceiver function of the session management network element or SMF network element in the above method, such as executing S301, and the processing module 902 is used to implement other functions of the session management network element or SMF network element in the above method except the transceiver function, such as executing S302.

[0377] Optionally, the transceiver module 901 may include a sending module ( Fig. 9 ) and a receiving module ( Fig. 9 The sending module is used to implement the sending function of the communication device 900, and the receiving module is used to implement the receiving function of the communication device 900.

[0378] Optionally, the communication device 900 may further include a storage module ( Fig. 9 When the processing module 902 executes the program or instruction, the communication device 900 can execute the above method. Figure 3-Figure 7 The method shown is a function of a network device (such as a session management network element or an SMF network element).

[0379] It can be understood that the communication device 900 can be a network device, such as a session management network element or an SMF network element, or a chip (system) or other parts or components that can be set in the network device, or a device that includes a network device, which is not limited in this application.

[0380] In addition, the technical effects of the communication device 900 can be referred to Figure 3-Figure 7The technical effects of the communication method shown will not be repeated here.

[0381] Fig.10 A schematic diagram of the structure of the communication device provided in the embodiment of the present application Figure 2 Exemplarily, the communication device may be a network device, such as an access and mobility management network element or a session management network element, such as an AMF network element or an SMF network element, or a chip (system) or other component or assembly that can be set in a network device. Fig.10 As shown, the communication device 1000 may include a processor 1001. Optionally, the communication device 1000 may further include a memory 1002 and / or a transceiver 1003. The processor 1001 is coupled with the memory 1002 and the transceiver 1003, such as being connected via a communication bus.

[0382] Combine the following Fig.10 The components of the communication device 1000 are described in detail:

[0383] The processor 1001 is the control center of the communication device 1000, and may be a processor or a general term for multiple processing elements. For example, the processor 1001 is one or more central processing units (CPUs), or may be application specific integrated circuits (ASICs), or may be configured to implement one or more integrated circuits of the embodiments of the present application, such as one or more microprocessors (digital signal processors, DSPs), or one or more field programmable gate arrays (FPGAs).

[0384] Optionally, the processor 1001 may execute various functions of the communication device 1000 by running or executing a software program stored in the memory 1002 and calling data stored in the memory 1002, such as executing the above Figure 3-Figure 8 The communication method shown.

[0385] In a specific implementation, as an embodiment, the processor 1001 may include one or more CPUs, such as Fig.10 CPU0 and CPU1 are shown in FIG.

[0386] In a specific implementation, as an embodiment, the communication device 1000 may also include multiple processors, such as Fig.101001 and 1004 are shown in FIG. Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). A processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0387] The memory 1002 is used to store the software program for executing the solution of the present application, and the execution is controlled by the processor 1001. The specific implementation method can refer to the above method embodiment, which will not be repeated here.

[0388] Optionally, the memory 1002 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 1002 may be integrated with the processor 1001, or may exist independently and be accessed through the interface circuit ( Fig.10 (not shown) is coupled to the processor 1001, which is not specifically limited in the embodiment of the present application.

[0389] The transceiver 1003 is used for communication with other communication devices. For example, the communication device 1000 is a terminal, and the transceiver 1003 can be used to communicate with a network device, or to communicate with another terminal device. For another example, the communication device 1000 is a network device, and the transceiver 1003 can be used to communicate with a terminal, or to communicate with another network device.

[0390] Optionally, the transceiver 1003 may include a receiver and a transmitter ( Fig.10 The receiver is used to implement a receiving function, and the transmitter is used to implement a sending function.

[0391] Optionally, the transceiver 1003 may be integrated with the processor 1001, or may exist independently and communicate with the processor 1001 through the interface circuit ( Fig.10 (not shown) is coupled to the processor 1001, which is not specifically limited in the embodiment of the present application.

[0392] Understandably, Fig.10 The structure of the communication device 1000 shown in the figure does not constitute a limitation on the communication device. The actual communication device may include more or fewer components than those shown in the figure, or combine certain components, or arrange the components differently.

[0393] In addition, the technical effects of the communication device 1000 can refer to the technical effects of the methods described in the above method embodiments, which will not be repeated here.

[0394] The present application provides a communication system, which includes: Figure 3 The method shown is for accessing and mobility management network elements and session management network elements, or for performing Figure 4-Figure 7 AMF network element and SMF network element of the method shown, or for executing Figure 8 The method shown is an access and mobility management network element and an access network device.

[0395] The present application provides a computer-readable storage medium, including: a computer program or instruction; when the computer program or instruction is executed on a computer, the computer executes the above Figure 3-Figure 8 The method corresponding to any of the accompanying drawings.

[0396] The present application provides a computer program product, including a computer program or an instruction. When the computer program or the instruction is executed on a computer, the computer executes the above-mentioned Figure 3-Figure 8 The method corresponding to any of the accompanying drawings.

[0397] It should be understood that the processor in the embodiments of the present application may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0398] It should also be understood that the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0399] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0400] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0401] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0402] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0403] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0404] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0405] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0406] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0407] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0408] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks or optical disks.

[0409] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A communication method, characterized in that: The method comprises: The access and mobility management network element sends first information to the session management network element, wherein the first information is used to trigger the session management network element to report the amount of cached service data of the terminal, where the cached service data of the terminal is service data cached by the network when the terminal is in an inactive state; The access and mobility management network element receives a first data volume from the session management network element, where the first data volume is a data volume of cached service data of the terminal; The access and mobility management network element sends a second amount of data to an access network device of the terminal according to the first amount of data.

2. The method according to claim 1, characterized in that The access and mobility management network element sends first information to the session management network element, including: When the state of the terminal changes to a reachable state, the access and mobility management network element sends the first information to the session management network element.

3. The method according to claim 2, characterized in that The method further comprises: The access and mobility management network element determines that the state of the terminal changes to a reachable state.

4. The method according to claim 2 or 3, characterized in that: The first information is carried in a session context request message, and the first data volume is carried in a session context response message.

5. The method according to claim 1, characterized in that The first information includes first indication information, where the first indication information is used to instruct the session management network element to report the amount of cached service data of the terminal when a first timer times out.

6. The method according to claim 5, characterized in that The method further comprises: The access and mobility management network element determines, according to the discontinuous reception parameter of the terminal, a duration of the first timer; The access and mobility management network element sends the duration of the first timer to the session management network element.

7. The method according to claim 5 or 6, characterized in that: The first information also includes the duration of the first timer.

8. The method according to claim 1, characterized in that The first information includes second indication information, and the second indication information is used to instruct the session management network element to report the data volume of the cached service data of the terminal when the data volume of the cached service data of the terminal reaches a cached data volume threshold.

9. The method according to claim 8, characterized in that The first information also includes the cache data amount threshold.

10. The method according to claim 8 or 9, characterized in that: The first information is carried in a protocol data unit PDU session context update message, or the first information is carried in a mobile terminal termination MT response message.

11. The method according to claim 1, characterized in that: The first information includes third indication information, and the third indication information is used to instruct the session management network element to report the data volume of the service data of the terminal each time the network receives the service data of the terminal when the terminal is in an inactive and unreachable state.

12. The method according to claim 11, characterized in that The first information is carried in an MT response message, and the first data volume is carried in an MT request message.

13. The method according to any one of claims 1 to 12, characterized in that The first information also includes an identifier of a first quality of service QoS flow of the terminal, where the identifier of the first QoS flow is used to indicate that the cached service data of the terminal is data corresponding to the first QoS flow.

14. The method according to claim 13, characterized in that The first QoS flow supports SDT DRB small data transmission data bearer.

15. The method according to claim 14, characterized in that The method further comprises: The access and mobility management network element receives second information from an access network device of the terminal, wherein the second information includes information of the first QoS flow; The access and mobility management network element sends the first information to the session management network element, including: The access and mobility management network element sends the first information to the session management network element according to the information of the first QoS flow.

16. The method according to claim 15, characterized in that The second information further includes a data volume threshold of the SDT DRB, and the access and mobility management network element sends the first information to the session management network element, including: When the amount of data cached by the network is less than the data amount threshold of the SDT DRB, the access and mobility management network element sends the first information to the session management network element, wherein the data cached by the network is data corresponding to the first QoS flow.

17. The method according to any one of claims 1 to 16, characterized in that: The first data volume includes the data volume corresponding to at least one QoS flow of the terminal, and the second data volume is the data volume corresponding to the QoS flow supporting SDT DRB in the at least one QoS flow; or, The first data amount is the same as the second data amount.

18. The method according to any one of claims 1 to 17, characterized in that Before the access and mobility management network element sends the first information to the session management network element, the method further includes: The access and mobility management network element receives the session management network element mobile terminal termination MT request message, wherein the MT request message includes a third data amount, and the third data amount is the data amount of the cached service data of the terminal; When the terminal is in an inactive and unreachable state, the access and mobility management network element sends an MT response message to the session management network element according to the MT request message, wherein the MT response message is used to indicate that the terminal is unreachable.

19. A communication method, characterized in that: The method comprises: The session management network element receives first information from the access and mobility management network element, wherein the first information is used to trigger the session management network element to report the amount of cached service data of the terminal, where the cached service data of the terminal is service data cached by the network when the terminal is in an inactive state; The session management network element sends a first data volume to the access and mobility management network element according to the first information, where the first data volume is a data volume of cached service data of the terminal.

20. The method according to claim 19, characterized in that The first information is carried in a session context request message, and the first data volume is carried in a session context response message.

21. The method according to claim 19, characterized in that The first information includes first indication information, where the first indication information is used to instruct the session management network element to report the amount of service data of the terminal when the first timer times out; The session management network element sending a first amount of data to the access and mobility management network element according to the first information includes: When the first timer times out, the session management network element sends the first data volume to the access and mobility management network element.

22. The method according to claim 21, characterized in that The method further comprises: The session management network element starts the first timer when receiving the duration of the first timer from the access and mobility management network element.

23. The method according to claim 21 or 22, characterized in that: The first information also includes the duration of the first timer.

24. The method according to claim 19, characterized in that The first information includes second indication information, where the second indication information is used to instruct the session management network element to report the amount of cached service data of the terminal when the amount of cached service data of the terminal reaches a cached data amount threshold; The session management network element sending a first amount of data to the access and mobility management network element according to the first information includes: When the first data amount reaches the buffer data amount threshold, the session management network element sends the first data amount to the access and mobility management network element.

25. The method according to claim 24, characterized in that: The first information carries the cache data amount threshold.

26. The method according to claim 24 or 25, characterized in that The first information is carried in a protocol data unit PDU session context update message, or the first information is carried in a mobile terminal termination MT response message.

27. The method according to claim 19, characterized in that The first information includes third indication information, and the third indication information is used to instruct the session management network element to report the data volume of the service data of the terminal each time the network receives service data of the terminal when the terminal is in an inactive and unreachable state; The session management network element sending a first amount of data to the access and mobility management network element according to the first information includes: When the network receives the cached service data of the terminal, the session management network element sends to the access and mobility management network element that the cached service data received from the terminal this time is the first data volume.

28. The method according to claim 27, characterized in that The first information is carried in an MT response message, and the first data volume is carried in an MT request message.

29. The method according to any one of claims 19 to 28, characterized in that The first information also includes an identifier of a first quality of service QoS flow of the terminal, where the identifier of the first QoS flow is used to indicate that the cached service data of the terminal is data corresponding to the first QoS flow.

30. The method according to claim 29, characterized in that The first QoS flow supports SDT DRB small data transmission data bearer.

31. The method according to any one of claims 19 to 30, characterized in that The method further comprises: The session management network element obtains the first data volume locally from the session management network element according to the first information.

32. The method according to any one of claims 19 to 30, characterized in that The network element in the network includes a user plane network element, and the method further includes: The session management network element obtains the first data volume from the user plane network element according to the first information.

33. A communication device, characterized in that: The apparatus comprises: a module for executing the method as claimed in any one of claims 1-32.

34. A communication device, characterized in that: The communication device comprises: a processor and a memory; the memory is used to store computer instructions, and when the processor executes the instructions, the communication device executes the method according to any one of claims 1-32.

35. A communication system, characterized in that: The communication system comprises: an access and mobility management network element in the method according to any one of claims 1 to 18, and a session management network element in the method according to any one of claims 19 to 32.

36. A computer-readable storage medium, characterized in that: The computer-readable storage medium comprises a computer program or instructions, and when the computer program or instructions are executed on a computer, the computer is caused to perform the method according to any one of claims 1 to 32.

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