Data transmission method, device, and system

Abstract

The present application provides a data transmission method, an apparatus, and a system applied in the field of communication technology. The data transmission method includes the steps of: receiving a first radio resource control (RRC) message from a terminal device by a serving access network device, the first RRC message being used to establish a small data transmission (SDT); and sending a second or third RRC message to the terminal device if the serving access network device does not meet the requirements of the SDT, the second RRC message can be used to instruct the terminal device to terminate the SDT, and the third RRC message can be used to instruct the serving access network device to refuse to execute the SDT. Based on this solution, if the serving access network device does not meet the requirements of the SDT, it can refuse or terminate the SDT, and the terminal device can then reselect a cell and start the SDT again. Compared with a solution in which the terminal continues to wait in the current cell, the data transmission efficiency of the terminal device can be improved.

Description

[Technical Field]

[0001] [Related Applications] This application claims priority to Chinese Patent Application No. 202210043783.6, filed with the State Intellectual Property Office of the People's Republic of China on January 14, 2022, entitled "DATA TRANSMISSION METHOD, APPARATUS, AND SYSTEM," which is incorporated herein by reference in its entirety.

[0002] [Technical field] TECHNICAL FIELD Embodiments of the present application relate to the field of communication technology, and in particular to a data transmission method, device, and system. [Background technology]

[0003] In 5th generation new radio (5GNR) systems, the RRC_INACTIVE state is introduced in the radio resource control (RRC) layer. User equipment (UE) may enter the RRC_INACTIVE state when there is no data transmission. If the UE is transmitting data, it may switch from the RRC_INACTIVE state to the RRC_CONNECTED state to perform data transmission.

[0004] In some transmission scenarios, the data packets transmitted by the UE are very small, but the data packets are transmitted frequently, requiring the UE to frequently switch between RRC states. This occupies a large amount of signaling resources. However, occupying a large amount of signaling resources to transmit small data packets leads to a waste of signaling resources. To solve this problem, the prior art has proposed a small data transmission (SDT) technology that allows the UE to transmit data in the RRC inactive state. Summary of the Invention

[0005] The present application provides a data transmission method, apparatus, and system, and provides a processing solution to be used when a serving base station or an anchor base station does not meet the SDT requirements, for example, due to resource congestion at the serving base station or overload at the anchor base station. The present invention does not limit the reasons why a serving base station or an anchor base station does not meet the requirements for performing SDT.

[0006] To achieve the aforementioned objectives, the following technical solutions are used in this application.

[0007] According to a first aspect, there is provided a data transmission method, which may be applied to a serving access network device, the data transmission method comprising: First, receiving a first RRC message from a terminal device, the first RRC message being used to establish an SDT; sending a second RRC message or a third RRC message to the terminal device if the serving access network device does not meet the requirements of the SDT, for example due to resource congestion or network load, wherein the second RRC message can be used to instruct the terminal device to terminate the SDT, and the third RRC message can be used to instruct the serving access network device to refuse to perform the SDT; may include:

[0008] Based on this solution, if the serving access network device does not meet the requirements for performing SDT, it can reject or terminate the SDT in a timely manner, and the terminal device can then reselect a cell and start SDT again, which can reduce delays and improve the data transmission efficiency of the terminal device compared to a solution in which the terminal device continues to wait in the current cell.

[0009] Referring to the first aspect, in a possible implementation, the serving access network device not meeting the requirements of the SDT may be: When the first RRC message is received, the following may occur: the serving access network device does not support the SDT; congestion occurs in the serving access network device; or the load of the serving access network device is greater than a threshold.

[0010] Referring to the first aspect, in a possible implementation, the serving access network device not meeting the requirements of the SDT may be: The process of performing the SDT may include congestion occurring in the serving access network device, or the load of the serving access network device being greater than the threshold.

[0011] Based on the above two implementations, when the establishment of an SDT is requested or in the process of executing an SDT, if the serving access network device does not meet the requirements of the SDT, it can terminate or reject the subsequent SDT procedure, thereby improving the applicability and flexibility of the solution.

[0012] Referring to the first aspect, in a possible implementation, the second RRC message and the third RRC message each include a waiting time, which indicates a period of time that the terminal device waits before initiating a next communication connection.

[0013] Based on this solution, the terminal device can immediately reselect the current cell after initiating a communication connection to avoid the SDT failing again.

[0014] Referring to the first aspect, in a possible implementation, the second RRC message includes a first redirection parameter or a first cell reselection priority parameter, where the first redirection parameter is used for redirection and the first cell reselection priority parameter is used for cell reselection.

[0015] Based on this solution, the serving access network device may instruct the terminal device to terminate SDT transmission, while providing the terminal device with parameters for redirection or cell reselection so that the terminal device can reselect a cell according to the instruction of the serving access network device. This solution allows the terminal device to select a cell that is more suitable for starting SDT or another service, thereby improving the data transmission efficiency of the terminal device.

[0016] Referring to the first aspect, in a possible implementation, the second RRC message includes a suspend configuration, and the suspend configuration is used to instruct the terminal device to suspend the context of the terminal device.

[0017] Referring to the first aspect, in a possible implementation, the serving access network device is not an anchor access network device, and before sending the second RRC message to the terminal device, the data transmission method comprises: sending the fourth RRC message to the anchor access network device, where the fourth RRC message is used to request the anchor access network device to send the second RRC message; receiving the fifth RRC message from the anchor access network device, the fifth RRC message being a response message to the fourth RRC message, and the fifth RRC message including the second RRC message; It can be seen that the second RRC message used to instruct the terminal device to terminate the SDT is generated by the anchor access network device.

[0018] Referring to the first aspect, in a possible implementation, the fourth RRC message includes any one of a request indication, a redirect indication, or a cell reselection indication, wherein the request indication is used to request the anchor access network device to send the second RRC message, the redirect indication is used to instruct the serving access network device to recommend to the terminal device to perform redirection, and the cell reselection indication is used to instruct the serving access network device to recommend to the terminal device to perform cell reselection.

[0019] Based on this solution, when the serving access network device requests the anchor access network device to send a second RRC message for terminating the SDT, the serving access network device can further recommend the terminal device to perform redirection to the anchor access network device, so that the terminal device can select a more suitable cell for performing the SDT, thereby improving the data transmission efficiency of the terminal device.

[0020] Referring to the first aspect, in a possible implementation, when the second RRC message includes the first redirection parameter, the fourth RRC message includes the second redirection parameter, and the second redirection parameter is used to determine the first redirection parameter. When the second RRC message includes the first cell reselection priority parameter, the fourth RRC message includes the second cell reselection priority parameter, and the second cell reselection priority parameter is used to determine the first cell reselection priority parameter.

[0021] Based on this solution, a parameter indicating that the terminal device should perform redirection or cell reselection can be recommended by the serving access network device.

[0022] Referring to the first aspect, in a possible implementation, the fourth RRC message includes a waiting time indication and / or a first cause value, where the waiting time indication is used to instruct the anchor access network device to send the waiting time, and the first cause value indicates the reason why the serving access network device requests the anchor access network device to send the second RRC message.

[0023] Referring to the first aspect, in a possible embodiment, if the serving access network device determines that it does not meet the requirements of the SDT when receiving the first RRC message, the fourth RRC message may include a transmission instruction, which is used to indicate to the terminal device that it requests to perform the SDT.

[0024] Referring to the first aspect, in a possible embodiment, if the serving access network device determines in the process of performing the SDT that it does not meet the requirements of the SDT, the fifth RRC message can be further used to instruct the serving access network device to delete the context of the terminal device. The data transmission method can further include deleting the locally stored context of the terminal device.

[0025] Referring to the first aspect, in a possible embodiment, the first RRC message includes a first SDT data packet, and if the serving access network device does not meet the SDT requirements when receiving the first RRC message, the fourth RRC message further includes the first SDT data packet.

[0026] Based on this solution, even if it is decided to terminate or reject the SDT, data packets sent by the terminal device are not discarded to avoid wasting signaling resources.

[0027] Referring to the first aspect, in a possible embodiment, if the serving access network device determines in the process of executing the SDT that the requirements of the SDT are not met, after sending a third RRC message to the terminal device, the data transmission method comprises: sending a sixth RRC message to an anchor access network device, the sixth RRC message being used to instruct the anchor access network device to cancel the SDT; It may further include:

[0028] Referring to the first aspect, in a possible embodiment, the sixth RRC message further includes a second cause value, which is used to indicate the reason for canceling the SDT.

[0029] According to a second aspect, there is provided a data transmission method, which can be applied to an anchor access network device, and the data transmission method includes: First, receiving a fourth RRC message from the serving access network device, the fourth RRC message being used to request the anchor access network device to send a second RRC message; Next, sending a fifth RRC message to the serving access network device based on the fourth RRC message, the fifth RRC message including a second RRC message, the second RRC message being used to instruct the terminal device to terminate the SDT; may include:

[0030] Based on this solution, if the serving access network device does not meet the SDT requirements, the serving access network device can request the anchor access network device to send a second RRC message, which causes the serving access network device to forward the second RRC message to the terminal device, instructing the terminal device to terminate the SDT. If the serving access network device does not meet the SDT requirements, the SDT is terminated in time to prevent the terminal device from continuing to wait in the serving access network device's cell. This solution can reduce the SDT delay and improve the data transmission efficiency of the terminal device.

[0031]

[0013] Referring to the second aspect, in a possible implementation, the fourth RRC message includes any one of a request indication, a redirect indication, or a cell reselection indication, where the request indication is used to request the anchor access network device to transmit the second RRC message, the redirect indication is used to instruct the serving access network device to recommend to the terminal device to perform redirection, and the cell reselection indication is used to instruct the serving access network device to recommend to the terminal device to perform cell reselection. The data transmission method may further include determining that the fifth RRC message includes the second RRC message according to the request indication, the redirect indication, or the cell reselection indication.

[0032] Based on this solution, the serving access network device can explicitly (e.g., using a request indication) request the anchor access network device to terminate the SDT, or can implicitly (e.g., using a redirect indication or a cell reselection indication) request the anchor access network device to terminate the SDT, thereby improving the flexibility of the solution in this application.

[0033] Referring to the second aspect, in a possible implementation, the second RRC message includes a first redirection parameter or a first cell reselection priority parameter, where the first redirection parameter is used for redirection and the first cell reselection priority parameter is used for cell reselection.

[0034] In relation to the second aspect, in a possible implementation, if the second RRC message includes the first redirection parameter, the fourth RRC message further includes a second redirection parameter, and the data transmission method further includes a step of determining the first redirection parameter based on the second redirection parameter.If the second RRC message includes the first cell reselection priority parameter, the fourth RRC message further includes a second cell reselection priority parameter, and the data transmission method further includes a step of determining the first cell reselection priority parameter based on the second cell reselection priority parameter.

[0035] Based on this solution, the anchor access network device can determine the parameters that the terminal device will use to perform redirection or cell reselection based on the redirection parameters or cell reselection priority parameters recommended by the serving access network device.

[0036] Referring to the second aspect, in a possible implementation, the second RRC message includes a waiting time, which indicates a period of time that the terminal device waits before initiating a next communication connection.

[0037] Referring to the second aspect, in a possible implementation, the fourth RRC message includes a waiting time indication, and the data transmission method further includes determining a waiting time according to the waiting time indication.

[0038] Referring to the second aspect, in a possible implementation, the fourth RRC message further includes a first cause value, which indicates the reason why the serving access network device requests the anchor access network device to send the second RRC message.

[0039] Referring to the second aspect, in a possible implementation, the fourth RRC message includes a transmission instruction, and the transmission instruction is used to instruct the terminal device to request to perform SDT.

[0040]

[0013] Referring to the second aspect, in a possible embodiment, the fourth RRC message further includes a first SDT data packet. The data transmission method may further include transmitting the first SDT data packet to a user plane network element. Based on this solution, even if the terminal device is instructed to terminate the SDT, the already transmitted data packets are normally forwarded to the user plane network element, preventing the first data packet from being discarded and causing waste of signaling resources.

[0041] Referring to the second aspect, in a possible implementation, the fifth RRC message is further used to instruct the serving access network device to delete the context of the terminal device.

[0042] According to a third aspect, there is provided a data transmission method that can be applied to an anchor access network device, and the data transmission method includes the steps of first receiving a sixth RRC message from a serving access network device, where the sixth RRC message is used to instruct the anchor access network device to cancel an SDT; suspending a context of a terminal device that performs SDT based on the sixth RRC message; may include:

[0043] According to this solution, if the serving access network device does not meet the requirements of the SDT, the serving access network device can instruct the anchor access network device to cancel the next SDT. It can be seen that there are multiple ways to terminate the SDT. This solution improves the flexibility of the data transmission method in this application.

[0044] Referring to the third aspect, in a possible embodiment, the sixth RRC message further includes a second cause value, which is used to indicate the reason for canceling the SDT.

[0045] According to a fourth aspect, there is provided a data transmission method, which can be applied to an anchor access network device, and the data transmission method includes: First, deciding to terminate the SDT; Next, sending a seventh RRC message to the serving access network device, the seventh RRC message including a second RRC message, the second RRC message being used to indicate to the terminal device to terminate the SDT; may include:

[0046] Based on this solution, the anchor access network device can selectively and actively terminate the SDT, thereby improving the flexibility of the data transmission method in this application.

[0047] Referring to the fourth aspect, in a possible implementation, the second RRC message includes a first redirection parameter or a first cell reselection priority parameter, where the first redirection parameter is used for redirection and the first cell reselection priority parameter is used for cell reselection.

[0048] Referring to the fourth aspect, in a possible implementation, the second RRC message includes a waiting time, which indicates a period of time that the terminal device waits before initiating a next communication connection.

[0049] According to a fifth aspect, there is provided a data transmission method, which can be applied to a terminal device, and which comprises: First, the method includes sending a first RRC message to a serving access network device, the first RRC message being used to establish an SDT; stopping an SDT timer by the terminal device when a second RRC message or a third RRC message is received from the serving access network device, the second RRC message being used to instruct the terminal device to terminate the SDT, and the third RRC message being used to instruct the serving access network device to refuse to execute the SDT; may include:

[0050] Based on this solution, the terminal device can start the SDT using the first RRC message. Furthermore, after starting the SDT, the terminal device can stop the SDT timer if the terminal device receives an instruction to terminate the SDT or an instruction from the access network device to refuse to perform the SDT. This method can avoid long data transmission delays caused by the terminal device waiting for a long time in a specific cell.

[0051] Referring to the fifth aspect, in a possible implementation, the second RRC message is an RRC Cancel message, and the third RRC message is an RRC Reject message.

[0052] Referring to the fifth aspect, in a possible implementation, when the third RRC message is received, the data transmission method may further include a step of notifying an upper layer of an SDT failure and restarting an RNA timer, the RNA timer being used to indicate that the terminal device is in an RRC inactive state.

[0053] Referring to the fifth aspect, in a possible implementation, the data transmission method may further include a step of notifying an upper layer of an SDT end when the second RRC message is received.

[0054] Referring to the fifth aspect, in a possible implementation, the second RRC message may include a suspend configuration, and the data transmission method may further include a step of suspending the context of the terminal device and restarting an RNA timer.

[0055] Referring to a fifth aspect, in a possible implementation, after the terminal device transmits the first RRC message, the method comprises: The method further includes starting the SDT timer and stopping the RNA timer.

[0056] Referring to the fifth aspect, in a possible implementation, when the third RRC message is received, the data transmission method may further include a step of notifying the upper layer of an SDT failure and continuing to run a suspended RNA timer, the RNA timer being used to indicate that the terminal device is in an RRC inactive state.

[0057] Referring to the fifth aspect, in a possible implementation, the data transmission method may further include a step of notifying an upper layer of an SDT end when the second RRC message is received.

[0058] Referring to the fifth aspect, in a possible implementation, the second RRC message may include a suspend configuration, and the data transmission method may further include a step of suspending the context of the terminal device and continuing to run the suspended RNA timer.

[0059] Referring to a fifth aspect, in a possible implementation, after the terminal device transmits the first RRC message, the method comprises: The method further includes starting the SDT timer and suspending the RNA timer.

[0060] Referring to the fifth aspect, in a possible implementation, the second RRC message or the third RRC message includes a waiting time, which indicates a period of time that the terminal device waits before initiating a next communication connection.

[0061] Based on this solution, the terminal device can immediately reselect the current cell after initiating a communication connection to avoid the SDT failing again.

[0062]

[0023] Referring to the fifth aspect, in a possible implementation, the second RRC message includes a first redirection parameter, and the first redirection parameter is used for redirection. Based on this solution, the serving access network device may instruct the terminal device to terminate SDT transmission, while providing the terminal device with parameters for redirection or cell reselection, so that the terminal device can reselect a cell according to the instruction of the serving access network device.

[0063] Based on this solution, the terminal device can select a more suitable cell to perform SDT, and the data transmission efficiency for the terminal device to perform SDT can be improved.

[0064] Referring to a fifth aspect, in a possible implementation, when there is an untransmitted SDT data packet in the buffer of the terminal device, the data transmission method comprises: ignoring the waiting time, performing redirection based on the first redirection parameter, and triggering an SDT in a first cell to transmit the untransmitted SDT data packets in the buffer, the first cell being a serving cell after the terminal device has performed the redirection; It may further include:

[0065] Based on this solution, if there is an SDT data packet that has not been completely transmitted, redirection can be performed immediately regardless of the waiting time, and the redirection is performed based on the first redirection parameter sent by the access network device, so that the SDT initiated by the terminal device can be successfully performed in the new cell. This method reduces the SDT delay and ensures that the SDT data packet that should be transmitted can be transmitted in time.

[0066] Referring to a fifth aspect, in a possible implementation, the second RRC message includes a first cell reselection priority parameter, and the first cell reselection priority parameter is used for cell reselection.

[0067] Based on this solution, the terminal device can select a more suitable cell to perform SDT, and the data transmission efficiency for the terminal device to perform SDT can be improved.

[0068] Referring to a fifth aspect, in a possible implementation, when there is an untransmitted SDT data packet in the buffer of the terminal device, the data transmission method comprises: ignoring the waiting time, performing cell reselection based on the first cell reselection priority parameter, and triggering SDT in a second cell to transmit the untransmitted SDT data packets in the buffer, wherein the second cell is a serving cell after performing the cell reselection; It may further include:

[0069] Based on this solution, if there are SDT data packets that have not been completely transmitted, cell reselection can be performed immediately regardless of the waiting time, and cell reselection is performed based on the first cell reselection priority parameter sent by the access network device, so that the SDT initiated by the terminal device can be successfully performed in the new cell. This method reduces SDT delay and ensures that the SDT data packets that should be transmitted can be transmitted in time.

[0070] According to a sixth aspect, there is provided a communication device for implementing the above-mentioned method. The communication device may be a serving access network device in the first aspect, an anchor access network device in the second to fourth aspects, or a terminal device in the fifth aspect. The communication device may include corresponding modules, units, or means for implementing the above-mentioned method. The modules, units, or means may be implemented by hardware, software, or hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the above-mentioned functions.

[0071] In a possible implementation, the communication device includes a processing module and a transceiver module, the transceiver module configured to perform message reception and transmission operations by the communication device side in the method of the first, second, third, fourth or fifth aspect, and the processing module configured to perform message processing or control operations performed by the communication device side in the method of the first, second, third, fourth or fifth aspect.

[0072] In a seventh aspect, there is provided a communications device including a processor, the processor configured to be coupled to a memory and configured to read computer instructions stored in the memory and then perform the method of the first, second, third, fourth or fifth aspect in accordance with the computer instructions.

[0073] In a possible implementation, the communication device further includes the memory, the memory configured to store the computer instructions.

[0074] In a possible implementation, the communication device further includes a communication interface used by the communication device to communicate with another device, for example, the communication interface may be a transceiver, an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, associated circuitry, etc.

[0075] In a possible implementation, the communication device may be a chip or a chip system. When the communication device is a chip system, the communication device may include a chip, or may include a chip and other individual components.

[0076] In a possible implementation, when the communication device is a chip or a chip system, the communication interface may be an input / output interface, an interface circuit, an output circuit, an input circuit, a pin, an associated circuit, etc. on the chip or the chip system. The processor may also be realized as a processing circuit or a logic circuit.

[0077] According to an eighth aspect, there is provided a computer-readable storage medium storing instructions which, when executed on a computer, enable the computer to perform the method of the first, second, third, fourth or fifth aspect.

[0078] According to a ninth aspect, there is provided a computer program product comprising instructions which, when executed on a computer, enable the computer to carry out a method according to the first, second, third, fourth or fifth aspect.

[0079] According to a tenth aspect, there is provided a communication system including a generating unit for performing the data transmission method according to the first aspect, an updating unit for performing the data transmission method according to the second aspect, and an updating unit for performing the data transmission method according to the third aspect.

[0080] For technical effects achieved by implementing any of the sixth to tenth aspects, please refer to the technical effects achieved by implementing any of the first, second, third, fourth, or fifth aspects, and the details will not be described again here. [Brief explanation of the drawings]

[0081] [Figure 1] FIG. 1 is a diagram of a communication network architecture according to an embodiment of the present application.

[0082] [Figure 2] 2 is a schematic diagram of an interaction process in which a UE requests to resume an RRC connection according to an embodiment of the present application; FIG.

[0083] [Figure 3] 1 is a flowchart of SDT according to an embodiment of the present application.

[0084] [Figure 4] 10 is another flowchart of SDT according to an embodiment of the present application.

[0085] [Figure 5] 1 is a schematic diagram of the structure of a communication system according to an embodiment of the present application;

[0086] [Figure 6] FIG. 2 is a schematic diagram of the structure of another communication system according to an embodiment of the present application;

[0087] [Figure 7] 1 is a schematic diagram of the structure of a communication device according to an embodiment of the present application;

[0088] [Figure 8] 1 is a schematic diagram of a hardware structure of a UE according to an embodiment of the present application;

[0089] [Figure 9] 1 is a flowchart of a data transmission method according to an embodiment of the present application;

[0090] [Figure 10a] 1 is a flowchart of a data transmission method according to an embodiment of the present application when a serving access network device and an anchor access network device are the same access network device;

[0091] [Figure 10b] 10b is a flowchart of a specific implementation of the data transmission method shown in FIG. 10a;

[0092] [Figure 11a] 10 is another flowchart of a data transmission method according to an embodiment of the present application when the serving access network device and the anchor access network device are the same access network device;

[0093] [Figure 11b] 11b is a flowchart of a specific implementation of the data transmission method shown in FIG. 11a;

[0094] [Figure 12a] 1 is a flowchart of a data transmission method according to an embodiment of the present application when a serving access network device is different from an anchor access network device;

[0095] [Figure 12b] 12b is a flowchart of a specific implementation of the data transmission method shown in FIG. 12a;

[0096] [Figure 13a]1 is a flowchart of a data transmission method according to an embodiment of the present application when a serving access network device is different from an anchor access network device;

[0097] [Figure 13b] 13b is a flowchart of a specific implementation of the data transmission method shown in FIG. 13a;

[0098] [Figure 14a] 1 is a flowchart of a data transmission method according to an embodiment of the present application when a serving access network device is different from an anchor access network device;

[0099] [Figure 14b] 14b is a flowchart of a specific implementation of the data transmission method shown in FIG. 14a;

[0100] [Figure 15a] 1 is a flowchart of a data transmission method according to an embodiment of the present application when a serving access network device is different from an anchor access network device;

[0101] [Figure 15b] 15b is a flowchart of a specific implementation of the data transmission method shown in FIG. 15a;

[0102] [Figure 16a] 1 is a flowchart of a data transmission method according to an embodiment of the present application when a serving access network device is different from an anchor access network device;

[0103] [Figure 16b] 16b is a flowchart of a specific implementation of the data transmission method shown in FIG. 16a;

[0104] [Figure 17]2 is a flowchart for establishing a transmission link for SDT by a serving access network device and an anchor access network device according to an embodiment of the present application;

[0105] [Figure 18] 1 is a flowchart of a data transmission method according to an embodiment of the present application;

[0106] [Figure 19] 1 is a schematic diagram of the structure of a communication device according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0107] The following describes the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. In the description of the present application, unless otherwise specified, the character " / " indicates an "or" relationship between associated objects. For example, A / B may represent A or B. In this specification, "and / or" only describes the association relationship between associated objects and indicates that three relationships may exist. For example, A and / or B can indicate the following three cases: when only A exists, when both A and B exist, or when only B exists, and A and B may be singular or plural. Furthermore, in the description of the present application, unless otherwise specified, "plurality" means two or more than two. "At least one of the following items" or similar expressions means any combination of these items, including any combination of a single item or multiple items. For example, "at least one of a, b, or c" may represent a, b, c, ab, ac, bc, or abc, where a, b, and c may be singular or plural. Furthermore, in order to clearly describe the technical solutions of the embodiments of the present application, terms such as "first" and "second" are used in the embodiments of the present application to distinguish between identical or similar items having essentially the same function or purpose. Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity or execution order, and that terms such as "first" and "second" do not indicate clear distinctions. Furthermore, in the embodiments of the present application, terms such as "exemplary" and "for example" are used to denote an example, instance, or illustration. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be described as being preferred or having more advantages than another embodiment or design solution. In particular, the use of the words "exemplary" or "for example" is intended to present related concepts in a specific way for ease of understanding.

[0108] For ease of understanding, the following provides a brief explanation of some terms and related technologies in this application.

[0109] 1. 5th generation (5G) network architecture

[0110] Please refer to Figure 1. Figure 1 is a schematic diagram of a 5G network architecture. Figure 1 takes the network service architecture of a 5G system as an example to show the interaction relationships and corresponding interfaces between network functions and entities. The network functions and entities included in the 3rd generation partnership project (3GPP) service-based architecture (SBA) of the 5G system mainly include user equipment (UE), access network (AN) or radio access network (RAN), user plane function (UPF), data network (DN), access management function (AMF), session management function (SMF), authentication server function (AUSF), policy control function (PCF), application function (AF), network slice selection function (NSSF), unified data management (UDM), network exposure function (NEF), and network repository function (NRF).

[0111] A network function may be used as a network element running on dedicated hardware, a software instance running on dedicated hardware, or a virtual function instantiated on a suitable platform implemented, for example, on a cloud infrastructure.

[0112] The main functions of the network elements are described in detail below.

[0113] AN / RAN: The AN / RAN can include various forms of base stations, such as macro base stations, micro base stations (also called "small cells"), and distributed unit-control units (DU-CUs). Furthermore, a base station may alternatively be a radio controller in a cloud radio access network (CRAN) scenario, a relay station, an access point, a vehicular device, a wearable device, a network device in a future evolved public land mobile network (PLMN) network, etc. The AN / RAN can also include a broadband network gateway (BNG), a convergence switch, a non-3GPP access device, etc.

[0114] The AN / RAN is mainly responsible for functions such as radio resource management on the air interface side, uplink and downlink data classification, quality of service (QoS) management, data compression and encryption, completion of signaling processing by a control plane network element, or completion of data forwarding by a user plane function network element. The specific form and structure of the AN / RAN are not limited to the embodiments of this application. For example, in systems using different radio access technologies, the name of the device having base station functionality may be different. For example, it may be an evolved universal terrestrial radio access network (E-UTRAN) device such as an evolved NodeB (eNB or e-NodeB) in LTE, or a next generation radio access network (NG-RAN) device (e.g., gNB) in a 5G system.

[0115] UPF: The UPF mainly handles packet routing and forwarding, QoS processing of user plane data, and statistics on billing information. The transmission resources and scheduling functions for providing services to UEs in the UPF are managed and controlled by the SMF.

[0116] DN: DN is a network for data transmission. For example, DU is an operator service network, an Internet access network, a third-party service network, etc.

[0117] For the functions of each network element such as AUSF, NSSF, NEF, NRF, UDM, etc., please refer to the explanations and descriptions of the prior art, and the details will not be described here.

[0118] 2. Radio resource control (RRC) state:

[0119] 5GNR defines three RRC states: inactive, connected, and idle. The three states are as follows:

[0120] (1) Connection state: This is the RRC_CONNECTED state, also called the connected state. The connected state means that an RRC connection between the UE and the access network is established. When the UE is in the connected state, the connection between the UE and the access network (e.g., a base station) and the connection between the UE and the core network (e.g., an AMF unit) are established, and when data needs to be transmitted, the data is transmitted directly via the established connection. The RRC connection is used to process control plane messages between the UE and the access network.

[0121] (2) Inactive state: This is the RRC_INACTIVE state, also referred to as the inactive state or the third state. The inactive state means that the RRC connection between the UE and the access network (e.g., base station) is disconnected, but the connection between the access network (e.g., base station) corresponding to the UE and the core network (e.g., AMF) remains connected. In the prior art, when the UE is in the inactive state and needs to transmit data, the RRC connection between the UE and the access network (e.g., base station) must first be resumed, and then the data can be transmitted.

[0122] After the UE enters the inactive state, the UE context is suspended on the terminal side and the base station side, and the UE context is stored in the last cell in which the UE was located before the inactive state or the last cell serving the UE (also called the anchor cell). If there is a data and / or signaling transmission requirement, the UE can obtain the UE context by initiating an RRC resume request (RRCResumeRequest) to resume the RRC connection based on the UE context. The UE context includes, for example, the UE security context or the UE capability information.

[0123] (3) Idle state: That is, RRC_IDLE. The inactive state means that the RRC connection between the UE and the access network device (e.g., base station) is established, and the connection between the access network corresponding to the UE (e.g., base station) and the core network device (e.g., AMF) is not established. When the UE is in the idle state, if it needs to transmit data, it must first establish a connection between the UE and the access network device (e.g., base station) and a connection between the access network device (e.g., base station) and the core network device (e.g., AMF), and then it can transmit data.

[0124] In addition, the base station to which the cell in which the UE currently resides or the base station currently serving the UE belongs may be called the serving base station. The base station to which the cell in which the UE last resided before the UE became inactive or the base station that last served the UE before the UE became inactive may be called the anchor base station. Note that since UEs have mobility and the UE may move after becoming inactive, the serving base station and the anchor base station for the UE may be different.

[0125] 3. Switching from RRC inactive state to RRC connected state

[0126] In the prior art, when a UE needs to transmit data in an RRC inactive state, the UE can first switch to an RRC connected state before transmitting data and / or signaling. For example, Figure 2 shows a complete procedure for switching from an RRC inactive state to an RRC connected state. As shown in Figure 2, the switching procedure may include the following steps:

[0127] Step 201: A UE in an RRC inactive state sends an RRC resume request (RRCResumeRequest) message to a serving base station.

[0128] Step 202: If the serving base station of the UE is not the anchor base station of the UE, the serving base station sends a Retrieve UE CONTEXT REQUEST message to the anchor base station to request a context of the UE.

[0129] Step 203: The anchor base station sends a Retrieve UE CONTEXT RSPONSE message to the serving base station, which includes the context of the UE.

[0130] Step 204: After receiving the UE context acquisition response message, the serving base station sends an RRC resume (RRCResume) message to the UE, so that the UE can switch to an RRC connected state.

[0131] Step 205: After receiving the RRC resumption message, the UE switches to an RRC connected state.

[0132] Step 206: After the UE resumes to the RRC connected state, it sends an RRC Resume Complete message to the serving base station.

[0133] Step 207: After receiving the RRC resumption complete message, the serving base station sends Xn interface address indication (Xn-U address indication) information to the anchor base station.

[0134] Step 208: The serving base station sends a channel switch request (path switch request) message to the AMF, receives a channel switch response (path switch response) message, and performs channel switching to switch the channel of the core network device to the serving base station.

[0135] Step 209: After the channel switching, the serving base station sends a UE context release message to the anchor base station to instruct the anchor base station to release the context of the UE.

[0136] It should be understood that after step 208, the serving base station becomes the new anchor base station. Therefore, the original anchor base station (i.e., the anchor base station in FIG. 2) does not need to store the context of the UE and can release the context of the UE.

[0137] Step 210: After the channel switch, the UE in the RRC connected state can transmit data using UPF.

[0138] Step 211: After the data transmission is completed, the serving base station (also the anchor base station) may send an RRC Release (RRCRelease) message to the UE so that the UE may switch to an RRC inactive state.

[0139] The RRC release message may include a suspend configuration (suspendconfig) that is used to instruct the UE to suspend the UE's context.

[0140] If the UE that has returned to the inactive state needs to transmit data again, it can execute the above steps 201 to 211 again.

[0141] However, as can be seen from the above steps 201 to 211, if the number of data transmissions is relatively high, the UE needs to frequently switch between the inactive state and the connected state, thereby occupying a large amount of signaling resources. However, occupying a large amount of signaling resources to transmit small data packets leads to a waste of signaling resources. Therefore, a small data transmission (SDT) technology has been proposed that enables the UE to transmit data even in the RRC inactive state.

[0142] 4.SDT

[0143] There are two scenarios for SDT performed by a UE in an inactive state: anchor transition scenario and anchor non-transition scenario. Anchor transition refers to, when a UE requests SDT in an inactive state, executing a solution similar to steps 206 to 208 described above to switch the AMF channel to the current serving base station and transmitting data after the current serving base station becomes the anchor base station (i.e., anchor base station transition). Anchor non-transition refers to continuing to use the previous anchor base station to control data transmission without switching the AMF channel to the current serving base station.

[0144] For example, Figure 3 is a flowchart of performing SDT in an anchor migration scenario. As shown in Figure 3, the process may include the following steps:

[0145] Step 301: A UE in an RRC inactive state carries an SDT data packet in an RRC resume request message sent to a serving base station, where the RRC resume request message carrying the SDT data packet can be used to request execution of the SDT.

[0146] Step 302: If the serving base station of the UE is not the anchor base station of the UE, the serving base station sends a UE context acquisition request message to the anchor base station, where the UE context acquisition request message may include an SDT instruction, instructing the anchor base station to perform SDT.

[0147] Step 303: The anchor base station sends a UE context acquisition response message to the serving base station.

[0148] Step 304: After receiving the UE context acquisition response message, the serving base station sends Xn interface address indication information to the anchor base station.

[0149] Step 305: The serving base station sends a channel switch request message to the AMF, receives a channel switch response message, and performs a channel switch to switch the channel of the core network device to the serving base station.

[0150] Step 306: After the channel switch, the serving base station directly sends the SDT data packet carried by the UE in the RRC resume request message to the UPF.

[0151] Step 307: After the channel switching, the serving base station further sends a UE context release message to the anchor base station to instruct the anchor base station to release the context of the UE.

[0152] Step 308: After the channel change, the UE transmits the UPF and subsequent SDT data packets via the serving base station.

[0153] Step 309: After the data transmission is completed, the serving base station (also the anchor base station) sends an RRC Release message to the UE.

[0154] The RRC release message may include a suspend configuration used to instruct the UE to suspend the UE's context.

[0155] For example, Figure 4 is a flowchart of performing SDT in an anchor non-migration scenario. As shown in Figure 4, the process may include the following steps:

[0156] Step 401: A UE in an RRC inactive state carries an SDT data packet in an RRC resume request message sent to a serving base station, where the RRC resume request message carrying the SDT data packet can be used to request execution of the SDT.

[0157] Step 402: If the serving base station of the UE is not the anchor base station of the UE, the serving base station sends a UE context acquisition request message to the anchor base station, where the UE context acquisition request message may include an SDT instruction, instructing the anchor base station to perform SDT.

[0158] Step 403: The anchor base station sends a UE context acquisition response message to the serving base station.

[0159] Step 404: The serving base station sends the SDT data packet carried by the UE in the RRC resume request message to the UPF via the anchor base station.

[0160] Step 405: The UE performs subsequent SDT data packet transmission with UPF via the serving base station and the anchor base station.

[0161] Step 406: After the data transmission is completed, the serving base station sends an RRC Release message to the UE.

[0162] The RRC release message may include a suspend configuration used to instruct the UE to suspend the UE's context.

[0163] However, in practical applications, the serving base station or the anchor base station may not be able to meet the requirements for performing SDT for some reasons, and there is currently no suitable solution to deal with this situation.

[0164] The embodiments of the present application provide a data transmission method that provides a processing solution when the serving base station or anchor base station does not meet the requirements of SDT.

[0165] Embodiments of the present application are applicable to, but not limited to, the following communication systems: narrow band-internet of things (NB-IoT) systems, wireless local access network (WLAN) systems, long term evolution (LTE) systems, 5G mobile communication systems, or communication systems beyond 5G, such as 6G systems, device to device (D2D) communication systems, or vehicle to vehicle internet.

[0166] The following describes a communication system provided in an embodiment of the present application using Fig. 5 as an example. As shown in Fig. 5, the communication system may include a terminal device 501 and a serving access network device 502. The serving access network device 502 is an access network device that currently provides service to the terminal device 501.

[0167] In the embodiment of the present application, the access network device to which the cell in which the terminal device currently exists belongs or the access network device currently serving the terminal device may be referred to as the serving access network device (e.g., the above-mentioned serving base station). The access network device to which the last cell in which the terminal device existed before becoming inactive belongs or the last access network device currently serving the terminal device may be referred to as the anchor access network device (e.g., the above-mentioned anchor base station). The serving access network device may be the same as the anchor access network device or may be different from the anchor access network device.

[0168] 6, when the serving access network device is different from the anchor access network device, in addition to the terminal device 601 and the serving access network device 602, the communication system further includes an anchor access network device 603. The anchor access network device 603 is the last access network device that provided service to the terminal device 601 before the terminal device 601 became inactive, and the anchor access network device 603 is different from the serving access network device 602.

[0169] Optionally, a 5G communication system is used as an example. A schematic diagram of a possible network architecture corresponding to the communication system shown in Figure 5 or Figure 6 and applicable to this embodiment of the present application can be shown in Figure 1. For example, the terminal device 601 may be the UE in Figure 1, and the serving access network device 602 or the anchor access network device 603 may be a device in the AN or RAN shown in Figure 1.

[0170] The system architecture described in this embodiment of the present application is intended to more clearly explain the technical solution in this embodiment of the present application, but is not intended to limit the technical solution provided in this embodiment of the present application. Those skilled in the art can understand that the technical solution provided in this embodiment of the present application can also be applied to similar technical problems as network architecture evolves and new service scenarios emerge.

[0171] The access network device of the present application may be a device disposed in a wireless access network and providing wireless communication functions to terminal devices. The access network device in this embodiment of the present application may be a base station, so that the serving access network device 602 may be a serving base station, and the anchor access network device 603 may be an anchor base station. The base station may include various types, such as a macro base station, a micro base station (also called a small cell), a relay station, or an access point. In a system using different radio access technologies, the access network device may be, for example, a Base Transceiver Station (BTS) in a global system for mobile communication (GSM) or code division multiple access (CDMA) network, a NodeB (NB) in a wideband code division multiple access (WCDMA) network, an eNB or evolutionary NodeB (eNodeB) in a Long Term Evolution (LTE) network, or a base station in a 5G network or a future evolved public land mobile network (PLMN). Alternatively, the access network device may be a broadband network gateway (BNG), an aggregation switch, or a non-3GPP access device. The access network device may also be a radio controller, a transmission and reception point (TRP), or a device including a TRP in a cloud radio access network (CRAN). This is not specifically limited in this embodiment of the present application.

[0172] The terminal device in the embodiments of the present application may be a device having a wireless transceiver function, and may be located indoors, outdoors, a mobile terminal, on land including in a vehicle, on the water (e.g., a ship), or in the air (e.g., an airplane, a balloon, or a satellite). The terminal device may be a UE, access terminal, terminal device, subscriber unit, mobile station (MS), mobile console, remote station, remote terminal, mobile device, wireless communication device, terminal agent, terminal equipment, etc. in a 5G network or a future evolved public land mobile network (PLMN). An access terminal may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication capabilities, a computing device, another processing device connected to a wireless modem, an in-vehicle device, a wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, 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, etc. The terminal may be mobile or fixed.

[0173] Optionally, the terminal device, the serving access network device, and the anchor access network device in this embodiment of the present application may use the component structure shown in Fig. 7 or may include the components shown in Fig. 7. Fig. 7 is a schematic diagram of the structure of a communication device 70 according to an embodiment of the present application. As shown in Fig. 7, the communication device 70 includes one or more processors 701, a communication line 702, and at least one communication interface (in Fig. 7, as an example for illustration, only a communication interface 703 and one processor 701 are included), and may optionally further include a memory 704.

[0174] The processor 701 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to control program execution of the solution of the present application.

[0175] The communication lines 702 may include channels for communicating between different components.

[0176] The communication interface 703 may be a transceiver module configured to communicate with other devices or communication networks, such as Ethernet, RAN, wireless local area networks (WLAN), etc. For example, the transceiver module may be a device such as a transceiver or a transceiver machine. Optionally, the communication interface 703 may alternatively be a transceiver circuit located within the processor 701 to provide signal input and output to the processor.

[0177] The memory 704 may be any device having storage capabilities. For example, the memory may be read-only memory (ROM), another type of static storage device capable of storing static information and instructions, random access memory (RAM), or another type of dynamic storage device capable of storing information and instructions, or may be electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), or another optical disk storage device, optical disk storage device (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium usable to carry or store program code expected in the form of instructions or data structures and accessible by a computer. However, the memory is not limited thereto. The memory may exist independently and be connected to the processor via communication line 702. Alternatively, the memory may be integrated into the processor.

[0178] The memory 704 is configured to store computer-executable instructions for implementing the solution of the present application, and the processor 701 controls the execution. The processor 701 is configured to execute the computer-executable instructions stored in the memory 704 to implement the data transmission method provided in the embodiment of the present application.

[0179] Alternatively, optionally, in this embodiment of the present application, the processor 701 can perform processing-related functions in the data transmission method provided in the following embodiments of the present application, and the communication interface 703 is responsible for communication with other devices or communication networks, which is not specifically limited in this embodiment of the present application.

[0180] Optionally, the computer-executable instructions in this embodiment of the present application may also be referred to as application code, which is not specifically limited in this embodiment of the present application.

[0181] In a particular implementation, in an embodiment, the processor 701 may include one or more CPUs, such as CPU0 and CPU1 of FIG.

[0182] In particular implementations, in embodiments, communications device 70 may include multiple processors, such as processor 701 and processor 707 of FIG. 7. Each of the processors may be a single-core processor or a multi-core processor. A processor herein may include, but is not limited to, at least one of the following: a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a microcontroller unit (MCU), an artificial intelligence processor, or various computing devices that execute software. Each computing device may include one or more cores that execute software instructions to perform operations or processes.

[0183] In a specific implementation, in one embodiment, the communication device 70 may further include an output device 705 and an input device 706. The output device 705 communicates with the processor 701 and may display information in a number of ways. For example, the output device 705 may be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, a projector, or the like. The input device 706 communicates with the processor 701 and may receive input from a user in a number of ways. For example, the input device 706 may be a mouse, a keyboard, a touch screen, or a sensor device.

[0184] The communication device 70, sometimes referred to as a communication appliance, may be a general-purpose device or a dedicated device. For example, the communication device 70 may be a desktop computer, a portable computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, an embedded device, a terminal device as described above, a network device as described above, or a device having a structure similar to that in FIG. 7. The type of communication device 70 is not limited to this embodiment of the present application.

[0185] Optionally, Figure 8 is a schematic diagram of a hardware structure of a UE. As shown in Figure 8, in some embodiments, the structure of a UE is shown in Figure 8, and the UE may include a processor 810, an external memory interface 820, an internal memory 821, a universal serial bus (USB) interface 830, a charging management module 840, a power management module 841, a battery 842, an antenna 1, an antenna 2, a mobile communication module 850, a wireless communication module 860, an audio module 870, a speaker 870A, a receiver 870B, a microphone 870C, a headset jack 870D, a sensor module 880, a button 890, a motor 891, an indicator 892, a camera 893, a display 894, a subscriber identification module (SIM) card interface 895, etc. The sensor module 880 may include a pressure sensor 880A, a gyroscope sensor 880B, an air pressure sensor 880C, a magnetic sensor 880D, an acceleration sensor 880E, a distance sensor 880F, an optical proximity sensor 880G, a fingerprint sensor 880H, a temperature sensor 880J, a touch sensor 880K, an ambient light sensor 880L, a bone conduction sensor 880M, and the like.

[0186] It can be understood that the structure shown in this embodiment does not constitute a specific limitation for the UE. In some other embodiments, the UE may include more or fewer components than those shown, some components may be combined, some components may be separated, or the components may be arranged in a different manner. The components in the figure may be implemented by hardware, software, or a combination of software and hardware.

[0187] The processor 810 may include one or more processing units. For example, the processor 810 may include an application processor (AP), a modem, a graphics processing unit (GPU), an image signal processor (ISP), a controller, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU). The different processing units may be separate devices or may be integrated into one or more processors.

[0188] The charging management module 840 is configured to receive a charging input from a charger, which may be a wireless charger or a wired charger.

[0189] The power management module 841 is configured to connect to the battery 842, the charging management module 840, and the processor 810. The power management module 841 receives input from the battery 842 and / or the charging management module 840 and provides power to the processor 810, the internal memory 821, the display 894, the camera 893, the wireless communication module 860, etc.

[0190] The wireless communication function of the UE can be realized via antenna 1, antenna 2, mobile communication module 850, wireless communication module 860, modem, baseband processor, etc.

[0191] Antenna 1 and Antenna 2 are configured to transmit and receive electromagnetic signals. Each antenna in the UE can be configured to cover one or more communication frequency bands. Different antennas can be multiplexed to increase antenna utilization.

[0192] The mobile communication module 850 can provide a solution for, for example, 2G / 3G / 4G / 5G wireless communication applied to the UE.

[0193] The wireless communication module 860 can provide wireless communication solutions applied to the UE, including wireless local area networks (WLAN) (e.g., wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite systems (GNSS), frequency modulation (FM), near field communication (NFC) technology, infrared (IR) technology, etc. The wireless communication module 860 can be one or more components integrating at least one communication processing module. The wireless communication module 860 receives electromagnetic waves via the antenna 2, performs frequency modulation and filtering on the electromagnetic wave signals, and transmits the processed signals to the processor 810. The wireless communication module 860 can further receive signals to be transmitted from the processor 810, perform frequency modulation and amplification on the signals, and convert the processed signals into electromagnetic waves for emission via the antenna 2.

[0194] In this embodiment of the present application, the wireless communication module 860 may be configured to allow the UE to send an RRC connection resumption request to a network node and receive a response message from the network node.

[0195] The UE implements a display function through a GPU, a display 894, an application processor, etc. The GPU is a microprocessor for image processing, and is connected to the display 894 and the application processor.

[0196] The display 894 is configured to display images, videos, etc. The display 894 of the UE is capable of displaying a series of graphical user interfaces (GUIs).

[0197] The UE can realize photo functions through an ISP, a camera 893, a video codec, a GPU, a display 894, an application processor, and the like.

[0198] The camera 893 is configured to capture still images or video.

[0199] The external memory interface 820 can be configured to connect to an external storage card, for example a microSD card, to expand the storage capabilities of the UE.

[0200] The internal memory 821 may be configured to store computer-executable program code, which includes instructions, and the processor 810 executes the instructions stored in the internal memory 821 to perform various functional applications and data processing for the UE.

[0201] The UE may perform audio functions using an audio module 870, a speaker 870A, a receiver 870B, a microphone 870C, a headset jack 870D, an application processor, etc. The audio functions include, for example, music playback and recording. The UE may further include a pressure sensor 880A, an air pressure sensor 880C, a gyro sensor 880B, a magnetic sensor 880D, an acceleration sensor 880E, a distance sensor 880F, an optical proximity sensor 880G, an ambient light sensor 880L, a fingerprint sensor 880H, a temperature sensor 880J, a touch sensor 880K, a bone conduction sensor 880M, a button 890, a motor 891, an indicator 892, etc.

[0202] The SIM card interface 895 is configured to connect to a SIM card. The SIM card may be inserted into or removed from the SIM card interface 895 to connect to or separate from the UE. The UE may support one or N SIM card interfaces, where N is a positive integer greater than 1. The SIM card interface 895 may support a nano-SIM card, a micro-SIM card, a SIM card, etc. Multiple cards may be inserted into the same SIM card interface 895 at the same time. The SIM card interface 895 is also compatible with an external memory card. The UE interacts with a network through the SIM card to realize functions such as making calls and data communications.

[0203] Additionally, an operating system, such as the Harmony operating system, iOS operating system, Android operating system, or Windows operating system, runs on the above components. Applications can be installed and run on the operating system. In some other embodiments, there may be multiple operating systems running within the UE.

[0204] It should be noted that the hardware modules included in the UE shown in FIG. 8 are merely an example for illustrative purposes and do not limit the specific configuration of the UE. In fact, the UE provided in this embodiment of the present application may further include other hardware modules that have an interaction relationship with the hardware modules shown in the figure. This is not specifically limited here. For example, the UE may further include a flashlight or a microprojection device. As another example, if the UE is a PC, the UE may further include components such as a keyboard and a mouse.

[0205] The following describes a data transmission method provided in an embodiment of the present application with reference to FIGS. 1 to 8. The device in the following embodiment may have the components shown in FIG. 8. The operations, terms, etc. in the embodiment of the present application may be mutually referenced and are not limited. In the embodiment of the present application, the names of messages exchanged between devices or the names of parameters in the messages are merely examples. In a specific embodiment, other names may be used, but are not limited thereto.

[0206] 9 is a flowchart of a data transmission method according to an embodiment of the present application. As shown in FIG. 9, the data transmission method may include the following steps:

[0207] Step 901: The terminal device sends a first RRC message to a serving access network device. The serving access network device then receives the first RRC message from the terminal device. The first RRC message is used to establish an SDT.

[0208] Optionally, the first RRC message may be an RRC resume request message. It should be understood that the first RRC message is implemented using the RRC resume request message and is compatible with existing communication systems, thereby improving the compatibility and usability of the data transmission method in the present application.

[0209] Optionally, the first RRC message may include a first SDT data packet, where the first SDT data packet is a data packet that needs to be transmitted over an SDT.

[0210] Optionally, the first SDT data packet carried in the first RRC message may be used to enable the service access network device to identify that the first RRC message is used to establish an SDT, which may be understood as an implicit indication.

[0211] Optionally, the first RRC message may include indication information or identification information, and may use the indication information or identification information to explicitly instruct the service access network device to establish an SDT. This implementation may be understood as an explicit indication.

[0212] It should be noted that in this embodiment of the present application, the terminal device is in an RRC inactive state when it sends the first RRC message.

[0213] Step 902: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a second or third RRC message to the terminal device. Accordingly, the terminal device receives the second or third RRC message from the serving access network device. The second RRC message is used to instruct the terminal device to terminate the SDT, and the third RRC message is used to instruct the serving access network device to refuse to perform the SDT.

[0214] Optionally, if the serving access network device does not meet the requirements of the SDT, it may mean that the serving access network device does not meet the requirements of the SDT when receiving the first RRC message, or it may mean that the serving access network device does not meet the requirements of the SDT in the process of performing the SDT.

[0215] It should be understood that if the serving access network device does not meet the requirements of the SDT when receiving the first RRC message, it indicates that the serving access network device has not started to execute the SDT. If the serving access network device does not meet the requirements of the SDT in the process of executing the SDT, it indicates that the serving access network device has successfully established the SDT after receiving the first RRC message, and the SDT process may be triggered by the first RRC message.

[0216] Optionally, when the first RRC message is received, the serving access network does not meet the requirements for SDT may mean that the serving access network device does not support SDT, that congestion occurs in the serving access network device, or that the load of the serving access network device is greater than a threshold. The serving access network does not meet the requirements for SDT may mean that congestion occurs in the serving access network device or that the load of the serving access network device is greater than a threshold in the process of performing SDT. The load of the serving access network exceeds a threshold may mean that excessive load is caused by congestion occurring in the serving access network. Or, the serving access network device needs to redirect the terminal to a different frequency layer based on the load balancing requirements of the network.

[0217] Step 903: When the terminal device receives a second RRC message or a third RRC message from the serving access network device, the terminal device stops the SDT timer. The second RRC message is used to instruct the terminal device to terminate the SDT, and the third RRC message is used to instruct the serving access network device to refuse to execute the SDT.

[0218] Optionally, the terminal device may start the SDT timer when sending the first RRC message, and then stop the SDT timer when the SDT ends or fails.

[0219] In this embodiment of the present application, if the serving access network device does not meet the requirements of the SDT, the serving access network device can send a second RRC message to instruct the terminal device to terminate the SDT, or send a third RRC message to instruct the serving access network device to refuse to perform the SDT, so that the terminal device can stop the SDT timer in time (meaning that the SDT will end), and avoid long data transmission delays caused by the terminal device continuing to wait in the current cell.

[0220] Furthermore, the reason why the serving access network device does not meet the requirements of the SDT may include a load greater than a threshold, in which case the SDT is terminated or rejected, thereby preventing the SDT from increasing the load on the serving access network device and implementing load balancing.

[0221] Optionally, the serving access network device and the anchor access network device in the embodiment shown in Figure 9 can have the following two relationships: they are the same access network device, or they are different access network devices. Specific embodiments of the embodiment shown in Figure 9 under these two relationships are respectively described below.

[0222] 10a shows a specific implementation of the embodiment shown in FIG. 9 when the serving access network device and the anchor access network device are the same access network device and the serving access network device does not meet the requirements of SDT when receiving the first RRC message. As shown in FIG. 10a, the method may include the following steps:

[0223] Step 1001a: The terminal device sends a first RRC message to a serving access network device (also an anchor access network device). Thus, the serving access network device receives the first RRC message from the terminal device. The first RRC message is used to establish an SDT.

[0224] For step 1001a, refer to the description of step 901. Details will not be described again here.

[0225] Step 1002a: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a second RRC message to the terminal device. Accordingly, the terminal device receives the second RRC message from the serving access network device. The second RRC message is used to instruct the terminal device to terminate the SDT.

[0226] For a description of the access network devices that do not meet the requirements of the SDT, please refer to the description of step 902. The details will not be repeated here.

[0227] If the serving access network device and the anchor access network device are the same access network device, the second RRC message is generated by the serving access network device.

[0228] Optionally, the second RRC message may be implemented by an RRC Cancel message.

[0229] Optionally, the second RRC message may include a suspend configuration instructing the terminal device to suspend its context, which facilitates the terminal device continuing to use the context to re-initiate the communication connection at a later time.

[0230] Optionally, the second RRC message may include a wait time, which may be used to indicate a period of time that the terminal device waits before initiating a next communication connection. This embodiment of the present application does not limit the next communication connection initiated by the terminal device, and the communication connection may mean that the terminal device sends signaling to the access network device to establish a connection between the terminal device and the access network device so that the terminal device can communicate with the access network device. For example, the communication connection may be an RRC connection, an SDT connection, etc.

[0231] Note that even if the terminal device immediately initiates a communication connection again (e.g., re-triggering SDT) after receiving the second RRC message, the current serving access network device may still be selected by the terminal device. However, if the current serving access network device does not meet the requirements for SDT, the communication connection initiated by the terminal device will be terminated again, resulting in a waste of signaling resources. If the second RRC message includes a waiting time, the terminal device can initiate the communication connection after the waiting time. If the serving access network device's capabilities recover sufficiently to perform SDT within the waiting time of the terminal device, the SDT retriggered by the terminal device will then be successful, even if the terminal device selects the current serving access network device. For example, in an example where congestion occurs in the serving access network device, if the serving access network device is not congested after the terminal device waits for a certain period of time, the terminal device will then re-trigger SDT, and the SDT will be successful.

[0232] In a possible implementation, the format of the waiting time of the second RRC message may be as follows:

number

[0233] Optionally, the second RRC message may include a first redirection parameter or a first cell reselection priority parameter, where the first redirection parameter is used for redirection and the first cell reselection priority parameter is used for cell reselection. Since the second RRC message carries the first redirection parameter or the first cell reselection priority parameter, the terminal device performs redirection or cell reselection based on the first redirection parameter or the first cell reselection priority parameter, thereby improving the success rate of the terminal device's re-triggering of SDT.

[0234] In a possible implementation, the first redirection parameter may be a carrier redirection parameter, and may include at least one of the following: a redirection frequency tier, a priority, a redirection radio access technology (RAT) type (e.g., LTE), a redirection core network type (e.g., evolved packet core network (EPC)), 5G core (five generation core)), and redirection frequency information (e.g., subcarrier spacing, absolute radio frequency channel number (ARFCN), and synchronization signal block measurement timing configuration (SSB-MTC)).

[0235] In a possible implementation, the format of the first redirection parameter in the second RRC message may be as follows:

number

[0236] The first cell reselection priority parameter may be a parameter of a neighboring cell (also called a neighbor cell) of the current access cell. The first cell reselection priority parameter may include at least one of the following: a frequency priority list (e.g., NR frequency priority or LTE frequency priority) and a cell selection priority list (e.g., cell frequency priority or cell absolute priority).

[0237] In a possible implementation, the format of the first cell reselection priority parameter in the second RRC message may be as follows:

number

[0238] Step 1003a: The terminal device stops the SDT timer.

[0239] Optionally, the terminal device can start the SDT timer when sending the first RRC message, and since the second RRC message is used to instruct the terminal device to terminate the SDT, the terminal device can stop the SDT timer after receiving the second RRC message.

[0240] Optionally, the terminal device can further notify an upper layer of the SDT termination. The upper layer is a layer above the protocol layer of the terminal device. For example, the upper layer can be a non-access stratum (NAS).

[0241] Optionally, the second RRC message may include a suspend configuration, and the terminal device may suspend the terminal device's context. Suspending the terminal device's context means that the terminal device remains in an RRC inactive state. In this case, the terminal device can restart the RNA timer or continue running the RNA timer in a suspended state. RNA stands for a radio access network (RAN) home location-based notification area, and the RNA timer is used to indicate that the terminal device is in an RRC inactive state. Based on this solution, the terminal device in the inactive state can then resend the first RRC message to the access network device to re-request execution of the SDT.

[0242] Optionally, the terminal device may stop or pause the RNA timer when sending the first RRC message.

[0243] It should be noted that restarting an RNA timer and keeping an RNA timer running are two different implementations provided in this application.

[0244] Optionally, if the second RRC message is an RRC release message and does not carry a suspend configuration, the terminal device may release its context after receiving the second RRC message and switch from the RRC inactive state to the RRC idle state. Note that after entering the RRC idle state, if the terminal device subsequently needs to start a next communication connection, it must switch to the RRC connected state before starting the communication connection.

[0245] Optionally, if the second RRC message includes a waiting time, the terminal device can start the next communication connection after the waiting time starting at a specific time point, which may be, for example, the time point when the second RRC message is received by the terminal device.

[0246] Optionally, if the second RRC message includes the first redirection parameter or the first cell reselection priority parameter, the terminal device may perform redirection based on the first redirection parameter or perform cell reselection based on the first cell reselection priority parameter when starting a next communication connection, and may start the next communication connection in the serving cell after redirection or in the serving cell after cell reselection.

[0247] This embodiment of the present application does not limit the next communication connection initiated by the terminal device, and the communication connection may mean that the terminal device sends signaling to the access network device to establish a connection between the terminal device and the access network device so that the terminal device can communicate with the access network device. For example, the communication connection may be an RRC connection, an SDT connection, etc.

[0248] Optionally, when the second RRC message includes a waiting time, if there are unsent SDT data packets in the terminal device's buffer, the terminal device may ignore the waiting time and immediately re-trigger the SDT.

[0249] In another possible implementation, when the second RRC message includes the waiting time and the first redirection parameter, if untransmitted SDT data packets exist in the buffer of the terminal device, the terminal device may ignore the waiting time, perform redirection based on the first redirection parameter, and trigger SDT in the first cell to transmit the untransmitted SDT data packets in the buffer, where the first cell is the serving cell after the terminal device performs redirection.

[0250] In a possible implementation, when the second RRC message includes the waiting time and the first cell reselection priority parameter, if untransmitted SDT data packets exist in the buffer of the terminal device, the terminal device may ignore the waiting time, perform cell reselection based on the first cell reselection priority parameter, and trigger SDT in the second cell to transmit the untransmitted SDT data packets in the buffer, where the second cell is the serving cell after cell reselection is performed.

[0251] Optionally, because the serving access network device is an anchor access network device, if the first RRC message includes a first SDT data packet, the serving access network device may further send the first SDT data packet to a user plane network element (such as a UPF), so that the first SDT data packet carried in the first RRC message is not discarded, thereby improving signaling utilization efficiency.

[0252] From the data transmission method shown in Figure 10a, it can be seen that in this embodiment of the present application, if the serving access network device does not meet the requirements of the SDT, the serving access network device sends a second RRC message to terminate the SDT, thereby preventing the terminal from continuing to wait in the current cell. This method improves the data transmission efficiency of the terminal device. In addition, the second RRC message may include a waiting time, a redirection parameter, a cell reselection parameter, etc., so that the terminal device can perform redirection or cell reselection according to the instructions of the access network device. In this way, the SDT can prevent an increase in the load on the serving access network device, and load balancing can be achieved.

[0253] Taking the example where the terminal device is a UE, the access network device is a base station, the first RRC message is an RRC resume request message, and the second RRC message is an RRC release message, the procedure of the data transmission method shown in Figure 10a will be described again. As shown in Figure 10b, the data transmission method may include the following steps:

[0254] Step 1001b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0255] Step 1002b: If the serving base station does not meet the requirements of the SDT, the serving base station sends an RRC Cancel message to the UE, which is used to instruct the UE to terminate the SDT.

[0256] Step 1003b: The UE stops the SDT timer.

[0257] 11a shows a specific implementation of the embodiment shown in FIG. 9 when the serving access network device and the anchor access network device are the same access network device and the serving access network device does not meet the requirements of SDT when receiving the first RRC message. As shown in FIG. 11a, the method may include the following steps:

[0258] Step 1101a: The terminal device sends a first RRC message to a serving access network device (also an anchor access network device), where the first RRC message is used to establish an SDT.

[0259] For step 1101a, refer to the description of step 901. Details will not be described again here.

[0260] Step 1102a: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a third RRC message to the terminal device. Accordingly, the terminal device receives the third RRC message from the serving access network device. The third RRC message is used to instruct the serving access network device to refuse to perform the SDT.

[0261] For a description of the access network devices that do not meet the requirements of the SDT, please refer to the description of step 902. The details will not be repeated here.

[0262] If the serving access network device and the anchor access network device are the same access network device, the third RRC message is generated by the serving access network device.

[0263] Optionally, the third RRC message may be implemented by an RRC rejection message.

[0264] Optionally, the third RRC message may include a waiting time, which may be used to indicate the period of time the terminal device waits before initiating the next communication connection.

[0265] In a possible implementation, the message format of the third RRC message may be as follows:

number

[0266] Step 1103a: The terminal device stops the SDT timer.

[0267] Optionally, the terminal device may start the SDT timer when sending the first RRC message. The third RRC message is used to instruct the serving access network device to refuse to perform the SDT, which means that the SDT will fail. Therefore, after receiving the second RRC message, the terminal device may stop the SDT timer.

[0268] Optionally, the terminal device may notify the upper layer of the SDT failure and restart the RNA timer or continue to run in a paused state.

[0269] Optionally, the terminal device may stop or pause the RNA timer when sending the first RRC message.

[0270] It should be noted that restarting an RNA timer and keeping an RNA timer running are two different implementations provided in this application.

[0271] Note that after receiving the third RRC message, the terminal device may know that the SDT has been rejected. In this case, the terminal device then retransmits the first RRC message and continues to request the establishment of the SDT. In this scenario, the terminal device needs to maintain the RRC inactive state in order to retransmit the first RRC message. Therefore, the terminal device may restart or continue to run the RNA timer in a paused state after receiving the third RRC message.

[0272] Optionally, if the third RRC message includes a waiting time, the terminal device waits for the waiting time in the third RRC message before initiating the next communication connection.

[0273] Optionally, because the serving access network device is an anchor access network device, if the first RRC message includes a first SDT data packet, the serving access network device may further send the first SDT data packet to a user plane network element (such as a UPF), so that the first SDT data packet carried in the first RRC message is not discarded, thereby improving signaling utilization efficiency.

[0274] Taking the example where the terminal device is a UE, the access network device is a base station, the first RRC message is an RRC resume request message, and the third RRC message is an RRC rejection message, the procedure of the data transmission method shown in Figure 11a will be described again. As shown in Figure 11b, the data transmission method may include the following steps:

[0275] Step 1101b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0276] Step 1102b: If the serving base station does not meet the requirements of the SDT, the serving base station sends an RRC rejection message to the UE. The RRC rejection message is used to instruct the serving base station to reject the execution of the SDT.

[0277] Step 1103b: The UE stops the SDT timer.

[0278] 12a shows a specific implementation of the embodiment shown in FIG. 9 when the serving access network device is different from the anchor access network device and does not meet the requirements of SDT when the serving access network device receives the first RRC message. As shown in FIG. 12a, the method may include the following steps:

[0279] Step 1201a: The terminal device sends a first RRC message to a serving access network device, and the serving access network device receives the first RRC message from the terminal device. The first RRC message is used to establish an SDT.

[0280] Step 1202a: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a third RRC message to the terminal device. Accordingly, the terminal device receives the third RRC message from the serving access network device. The third RRC message is used to instruct the serving access network device to refuse to perform the SDT.

[0281] Step 1203a: The terminal device stops the SDT timer.

[0282] For steps 1201a to 1203a, please refer to the relevant explanations for steps 1101a to 1103a, and the details will not be explained again here.

[0283] Optionally, if the first RRC message includes a first SDT data packet, the method may further include: Step 1204a: The serving access network device sends the first SDT data packet to the anchor access network device. Furthermore, after receiving the first SDT data packet, the anchor access network device may forward the first SDT data packet to a user plane network element (not shown in FIG. 12a). Based on this, the first SDT data packet carried in the first RRC message is not discarded, thereby improving signaling utilization efficiency. Note that the execution sequence of step 1204a is not limited in the present application, and for example, step 1204a may alternatively be executed before step 1202a or 1203a.

[0284] Taking the example where the terminal device is a UE, the access network device is a base station, the first RRC message is an RRC resume request message, and the third RRC message is an RRC rejection message, the procedure of the data transmission method shown in Figure 12a will be described again. As shown in Figure 12b, the data transmission method may include the following steps:

[0285] Step 1201b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0286] Step 1202b: If the serving base station does not meet the requirements of the SDT, the serving base station sends an RRC rejection message to the UE. The RRC rejection message is used to instruct the serving base station to reject the execution of the SDT.

[0287] Step 1203b: The UE stops the SDT timer.

[0288] Step 1204b: The serving base station sends a first SDT data packet carried in an RRC resume request message to the anchor base station.

[0289] 13a shows a specific implementation of the embodiment shown in FIG. 9, where the serving access network device is different from the anchor access network device and does not meet the requirements of SDT when the serving access network device receives the first RRC message. As shown in FIG. 13a, the method may include the following steps:

[0290] Step 1301a: The terminal device sends a first RRC message to the serving access network device. Then, the anchor access network device receives the first RRC message from the serving access network device. The first RRC message is used to establish an SDT.

[0291] For step 1301a, please refer to the relevant explanation for step 901. Details will not be explained again here.

[0292] Step 1302a: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a fourth RRC message to the anchor access network device. Accordingly, the anchor access network device receives the fourth RRC message from the serving access network device. The fourth RRC message is used to request the anchor access network device to send a second RRC message.

[0293] Optionally, the fourth RRC message requesting the anchor access network device to send the second RRC message can be implemented using a request indication, a redirect indication, or a cell reselection indication. That is, the fourth RRC message may include any one of a request indication, a redirect indication, or a cell reselection indication, where the request indication can be used to request the anchor access network device to send the second RRC message, the redirect indication can be used to instruct the serving access network device to recommend to the terminal device to perform redirection, and the cell reselection indication can be used to instruct the serving access network device to recommend to the terminal device to perform cell reselection. If the request indication is included, the fourth RRC message is understood to be an explicit request, and if the redirect indication or the cell reselection indication is included, the fourth RRC message is understood to be an implicit request.

[0294] Optionally, the fourth RRC message may be a UE context acquisition request message. The fourth RRC message being a UE context acquisition request message is equivalent to the fourth RRC message multiplexing an existing signaling message. In this case, the fourth RRC message needs to include additional indication information so that the anchor access network device can distinguish the fourth RRC message from the existing signaling message.

[0295] For example, the additional instruction information may be a transmission instruction, which is used to instruct the terminal device to request execution of the SDT. In a possible implementation, the transmission instruction may be an SDT indicator.

[0296] Optionally, the fourth RRC message may include a second redirection parameter that may be used to assist the anchor access network device in determining the first redirection parameter. Alternatively, the fourth RRC message may include a second cell reselection priority parameter that may be used to assist the anchor access network device in determining the first cell reselection priority parameter.

[0297] Optionally, the second redirection parameter sent by the serving access network device can be understood as a recommendation provided by the serving access network device to the anchor access network device so that the anchor access network device can determine the first redirection parameter. For the second cell reselection priority parameter, please refer to the description of the second redirection parameter. Details will not be described again here.

[0298] Optionally, the fourth RRC message includes a waiting time indication and / or a first cause value, where the waiting time indication is used to instruct the anchor access network device to send the waiting time, and the first cause value indicates the reason why the serving access network device requests the anchor access network device to send the second RRC message.

[0299] For example, if the serving access network device does not meet the requirements of the SDT due to network congestion, the first cause value may be network congestion.

[0300] Optionally, if the first RRC message includes a first SDT data packet, the serving access network device can add the first SDT data packet to a fourth RRC message and send the fourth RRC message to the anchor access network device, that is, the fourth RRC message includes the first SDT data packet.

[0301] Step 1303a: The anchor access network device sends a fifth RRC message to the serving access network device, so that the serving access network device receives the fifth RRC message from the anchor access network device.

[0302] The fifth RRC message is a response message to the fourth RRC message, and includes the second RRC message, which is used to instruct the terminal device to terminate the SDT. For the content of the second RRC message, please refer to the relevant description of the second RRC message in step 1002a. The details will not be described again here.

[0303] Optionally, the fourth RRC message may be a UE context acquisition request message, and the fifth RRC message may be a UE context acquisition response message.

[0304] Optionally, the second RRC message may be encapsulated in a fifth RRC message in the form of an RRC container.

[0305] Optionally, the fifth RRC message sent by the anchor access network device may be determined based on the fourth RRC message.

[0306] Optionally, if the fourth RRC message includes any one of a request indication, a redirect indication, or a cell reselection indication, the anchor access network device may determine that the fifth RRC message includes the second RRC message according to the request indication, the redirect indication, or the cell reselection indication. After receiving the redirect indication or the cell reselection indication, the anchor access network device can know that the serving access network device recommends that the terminal device perform redirection or cell reselection, and the serving access network device's implicit intention is that the serving access network device wants to terminate the SDT, so the anchor access network device can determine that the fifth RRC message includes the second RRC message used to instruct the terminal device to terminate the SDT.

[0307] Optionally, if the fourth RRC message includes a second redirection parameter, the anchor access network device may determine the first redirection parameter according to the second redirection parameter. If the fourth RRC message includes a second cell reselection priority parameter, the anchor access network device may determine the first cell reselection priority parameter according to the second cell reselection priority parameter.

[0308] Optionally, if the fourth RRC message includes a waiting time indication, the anchor access network device can determine the waiting time according to the waiting time indication.

[0309] Step 1304a: The serving access network device sends a second RRC message to the terminal device. Thus, the terminal device receives the second RRC message from the serving access network device. The second RRC message is used to instruct the terminal device to terminate the SDT.

[0310] It should be understood that after receiving the fifth RRC message, the serving access network device can forward the second RRC message in the fifth RRC message to the terminal device.

[0311] Step 1305a: The terminal device stops the SDT timer.

[0312] For step 1305a, please refer to the relevant description of step 1003a, and the details will not be described again here.

[0313] Optionally, if the first RRC message includes a first SDT data packet, the method may further include: Step 1306a: the serving access network device sends the first SDT data packet to the anchor access network device. For step 1306a, refer to the description of step 1204a. Details will not be described again here. Note that step 1306a is performed after step 1303a, and the execution sequence of step 1306a, step 1304a, and step 1305a is not limited.

[0314] Taking the example where the terminal device is a UE, the access network device is a base station, the first RRC message is an RRC resume request message, the second RRC message is an RRC release message, the fourth RRC message is a UE context acquire request message, and the fifth RRC message is a UE context acquire response message, the procedure of the data transmission method shown in Figure 13a will be described again. As shown in Figure 13b, the data transmission method may include the following steps:

[0315] Step 1301b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0316] Step 1302b: If the serving base station does not meet the requirements of the SDT, the serving base station sends a UE context acquisition request message to the anchor base station.

[0317] Step 1303b: The anchor base station sends a UE context acquisition response message to the serving base station, where the UE context acquisition response message carries an RRC release message.

[0318] Step 1304b: The serving base station sends an RRC Cancel message to the UE, which is used to instruct the terminal device to terminate the SDT.

[0319] Step 1305b: The UE stops the SDT timer.

[0320] Step 1306b: The serving base station sends a first SDT data packet carried in an RRC resume request message to the anchor base station.

[0321] Figure 14a shows a specific implementation of the embodiment shown in Figure 9 when the serving access network device is different from the anchor access network device and the access network device does not meet the requirements of SDT in the process of performing SDT. As shown in Figure 14a, the method may include the following steps:

[0322] Step 1401a: The terminal device sends a first RRC message to the serving access network device. Accordingly, the serving access network device receives the first RRC message from the terminal device. The first RRC message is used to establish an SDT. Please refer to the relevant description of step 901. The details will not be described again here.

[0323] It should be understood that if the method shown in Figure 14a is applied to a scenario in which the access network device does not meet the requirements of the SDT in the process of performing the SDT, the first RRC message is considered to be successful in triggering the SDT.

[0324] Step 1402a: The serving access network device establishes an SDT transmission link with the anchor access network device.

[0325] It should be understood that when the serving access network device receives the first RRC message, the capabilities of the serving access network device can meet the requirements for establishing an SDT, and the serving access network device can perform signaling interaction with the anchor access network device to establish a transmission link for the SDT.

[0326] Step 1403a: The terminal device performs subsequent SDT data transmission with the anchor access network device.

[0327] After the SDT transmission link is established, the terminal device can use the serving access network device to forward subsequent SDT data packets to the anchor access network device, and the anchor access network device transmits the SDT data packets to the user plane network element.

[0328] Step 1404a: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a fourth RRC message to the anchor access network device. Accordingly, the anchor access network device receives the fourth RRC message from the serving access network device. The fourth RRC message is used to request the anchor access network device to send a second RRC message.

[0329] From steps 1401a to 1403a, it can be seen that the transmission of SDT data is started before step 1404a. In step 1404a, the serving access network device does not meet the requirements of the SDT in the process of executing the SDT.

[0330] The content included in the fourth RRC message in step 1404a may be similar to the content included in the fourth RRC message in step 1302a, with the following difference: The fourth RRC message in step 1404a may be an RRC release request (RRCReleaseRequest) message, and the fourth RRC message does not include the first SDT data packet. In the scenario of Figure 14a, the first SDT data packet has already been sent to the anchor access network device after the transmission link for SDT is established.

[0331] Step 1405a: The anchor access network device sends a fifth RRC message to the serving access network device, where the fifth RRC message is a response message to the fourth RRC message, the fifth RRC message includes a second RRC message, and the second RRC message is used to instruct the terminal device to terminate the SDT.

[0332] It should be noted that for the content of the fifth RRC message, please refer to the relevant description of the fifth RRC message in step 1303a, and the details will not be described again here.

[0333] Optionally, if the fourth RRC message is an RRC Cancel Request message, the fifth RRC message may be an RRC Cancel Response (RRCReleaseResponse) message.

[0334] Optionally, the fifth RRC message may further be used to instruct the serving access network device to delete the context of the terminal device. Thus, after receiving the fifth RRC message, the serving access network device may delete the locally stored context of the terminal device.

[0335] Step 1406a: The serving access network device sends a second RRC message to the terminal device. Accordingly, the terminal device receives the second RRC message from the serving access network device. The second RRC message is used to instruct the terminal device to terminate the SDT.

[0336] It should be understood that after receiving the fifth RRC message, the serving access network device can forward the second RRC message in the fifth RRC message to the terminal device.

[0337] Step 1407a: The terminal device stops the SDT timer. Please refer to the relevant description of step 1003a. The details will not be described again here.

[0338] Optionally, if the fifth RRC message is not a one-way message, after the serving access network device deletes the locally stored context of the terminal device and sends the second RRC message to the terminal device, the method may further include: Step 1408a: The serving access network device sends a response message of the fifth RRC message to the anchor access network device. In a possible implementation, the response message of the fifth RRC message may be an RRC Release Complete (RRCReleaseComplete) message.

[0339] Optionally, if the first RRC message includes a first SDT data packet, the method may further include the following after step 1402a: step 1409a: the serving access network device sends the first SDT data packet to the anchor access network device. For step 1409a, refer to the description of step 1204a. The details will not be described again here.

[0340] Taking the example where the terminal device is a UE, the access network device is a base station, the first RRC message is an RRC resume request message, the second RRC message is an RRC release message, the fourth RRC message is an RRC release request message, the fifth RRC message is an RRC release response message, and the response message to the fifth RRC message is an RRC release complete message, the procedure of the data transmission method shown in Figure 14a will be described again. As shown in Figure 14b, the data transmission method may include the following steps:

[0341] Step 1401b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0342] Step 1402b: The serving base station establishes a transmission link for SDT with the anchor base station.

[0343] Step 1409b: The serving base station sends a first SDT data packet carried in an RRC resume request message to the anchor base station.

[0344] Step 1403b: The UE performs subsequent SDT data transmission with the anchor base station.

[0345] Step 1404b: If the serving base station does not meet the requirements of the SDT, the serving base station sends an RRC release request message to the anchor base station.

[0346] Step 1405b: The anchor base station sends an RRC Cancellation Response message to the serving base station, which carries the RRC Cancellation message.

[0347] Step 1406b: The serving base station sends an RRC Cancel message to the UE, which is used to instruct the terminal device to terminate the SDT.

[0348] Step 1407b: The UE stops the SDT timer.

[0349] Step 1408b: The serving base station sends an RRC release complete message to the anchor base station.

[0350] Figure 15a shows another specific implementation of the embodiment shown in Figure 9, when the serving access network device is different from the anchor access network device and does not meet the requirements of SDT in the process of performing SDT. As shown in Figure 15a, the method may include the following steps:

[0351] Step 1501a: The terminal device sends a first RRC message to the serving access network device, and the serving access network device receives the first RRC message from the terminal device. The first RRC message is used to establish an SDT.

[0352] Step 1502a: The serving access network device establishes an SDT transmission link with the anchor access network device.

[0353] Step 1503a: The terminal device performs subsequent SDT data transmission with the anchor access network device.

[0354] For steps 1501a to 1503a, please refer to the relevant explanations of steps 1401a to 1403a, and the details will not be described again here.

[0355] Step 1504a: If the serving access network device does not meet the requirements of the SDT, the serving access network device sends a third RRC message to the terminal device. Accordingly, the terminal device receives the third RRC message from the serving access network device. The third RRC message is used to instruct the serving access network device to refuse to perform the SDT.

[0356] Step 1505a: The terminal device stops the SDT timer.

[0357] For steps 1504a and 1505a, please refer to the relevant descriptions of steps 1102a and 1103a, and the details will not be described again here.

[0358] Step 1506a: The serving access network device sends a sixth RRC message to the anchor access network device. Accordingly, the anchor access network device receives a sixth RRC message from the serving access network device. The sixth RRC message is used to instruct the anchor access network device to cancel the subsequent SDT.

[0359] Optionally, the sixth RRC message may be referred to as an SDT cancel message.

[0360] Optionally, the sixth RRC message may further include a second cause value, which may be used to indicate the reason for canceling the SDT. For example, if the serving access network device decides to cancel the later SDT due to network congestion, the second cause value may be network congestion.

[0361] Step 1507a: The anchor access network device suspends the context of the terminal device running the SDT based on the sixth RRC message.

[0362] Optionally, if the first RRC message includes a first SDT data packet, the method may further include the following after step 1502a: step 1508a: the serving access network device sends the first SDT data packet to the anchor access network device. For step 1508a, refer to the description of step 1204a. The details will not be described again here.

[0363] Taking the example that the terminal device is a UE, the access network device is a base station, the first RRC message is an RRC resume request message, the third RRC message is an RRC rejection message, and the sixth RRC message is an RRC cancel message, the procedure of the data transmission method shown in Figure 15a will be described again. As shown in Figure 15b, the data transmission method may include the following steps:

[0364] Step 1501b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0365] Step 1502b: The serving base station establishes a transmission link for SDT with the anchor base station.

[0366] Step 1508b: The serving base station sends a first SDT data packet to the anchor base station.

[0367] Step 1503b: The UE performs a subsequent SDT data transmission with the anchor base station.

[0368] Step 1504b: If the serving base station does not meet the requirements of the SDT, the serving base station sends an RRC rejection message to the UE. The RRC rejection message is used to instruct the serving base station to reject the execution of the SDT.

[0369] Step 1505b: The UE stops the SDT timer.

[0370] Step 1506b: The serving base station sends an RRC cancellation message to the anchor base station. The RRC cancellation message is used to instruct the anchor base station to cancel the later SDT.

[0371] Step 1507b: The anchor base station suspends the context of the UE performing the SDT based on the RRC cancellation message.

[0372] It should be noted that the above-mentioned data transmission methods provided in Figures 9 to 15b all apply to scenarios where the serving access network device does not meet the requirements of the SDT and the termination or rejection of the SDT is triggered by the serving access network device. It should be understood that the anchor access network device can actively terminate the SDT.

[0373] Optionally, if the anchor access network device is the same as the serving access network device, the way in which the anchor access network device actively terminates the SDT may be to send a second RRC message to the terminal device. In this scenario, the process in which the anchor access network device actively terminates the SDT may be as described in step 1002a and step 1003a, and the details will not be described again.

[0374] Optionally, when the anchor access network device is different from the serving access network device, the anchor access network device may perform a data transmission method shown in Figure 16a to actively terminate the SDT. As shown in Figure 16a, the method may include the following steps:

[0375] Step 1601a: The terminal device sends a first RRC message to the serving access network device. The serving access network device then receives the first RRC message from the terminal device. The first RRC message is used to establish an SDT.

[0376] Step 1602a: The serving access network device establishes an SDT transmission link with the anchor access network device.

[0377] Step 1603a: The terminal device performs subsequent SDT data transmission with the anchor access network device.

[0378] For steps 1601a to 1603a, please refer to the relevant explanations of steps 1401a to 1403a, and the details will not be described again here.

[0379] Step 1604a: If the anchor access network device determines to terminate the SDT during the process of executing the SDT, the anchor access network device sends a seventh RRC message to the serving access network device. Accordingly, the serving access network device receives the seventh RRC message. The seventh RRC message includes a second RRC message, which is used to instruct the terminal device to terminate the SDT.

[0380] Optionally, the reasons why the anchor access network device decides to terminate the SDT may include, but are not limited to: the capability of the anchor access network device does not meet the requirements for subsequently performing the SDT (e.g., congestion occurs in the SDT process), or the anchor access network device experiences a timeout when receiving data packets (e.g., after the transmission link for the SDT is established, the anchor access network device does not receive SDT data packets for a long time).

[0381] Optionally, the seventh RRC message may be a context release request message.

[0382] Optionally, the seventh RRC message may further be used to instruct the serving access network device to release the context of the terminal device. Thus, after receiving the seventh RRC message, the serving access network device may delete the locally stored context of the terminal device.

[0383] For the content of the second RRC message, please refer to the relevant description of the second RRC message in step 1002. The details will not be described again here.

[0384] Step 1605a: The serving access network device sends a second RRC message to the terminal device. Thus, the terminal device receives the second RRC message from the serving access network device. The second RRC message is used to instruct the terminal device to terminate the SDT.

[0385] It should be understood that after receiving the seventh RRC message, the serving access network device can forward the second RRC message in the seventh RRC message to the terminal device.

[0386] Step 1606a: The terminal device stops the SDT timer. Please refer to the relevant description of step 1003a. The details will not be described again here.

[0387] Optionally, if the seventh RRC message is not a one-way message, after the serving access network device deletes the locally stored context of the terminal device and sends the second RRC message to the terminal device, the method may further include: Step 1607a: The serving access network device sends a response message of the seventh RRC message to the anchor access network device. In a possible implementation, the response message of the seventh RRC message may be an RRC release complete message.

[0388] Optionally, if the first RRC message includes a first SDT data packet, the method may further include the following after step 1602a: step 1608a: the serving access network device sends the first SDT data packet to the anchor access network device. For step 1608a, refer to the description of step 1204a. The details will not be described again here.

[0389] Taking the example where the terminal device is a UE, the device is a base station, the first RRC message is an RRC resume request message, the second RRC message is an RRC release message, the seventh RRC message is an RRC release request message, and the response message of the seventh RRC message is an RRC release complete message, the procedure of the data transmission method shown in Figure 16a will be described again. As shown in Figure 16b, the data transmission method may include the following steps:

[0390] Step 1601b: The UE sends an RRC resume request message to the serving base station, which is used to request the execution of the SDT.

[0391] Step 1602b: The serving base station establishes a transmission link for SDT with the anchor base station.

[0392] Step 1608b: The serving base station sends a first SDT data packet to the anchor base station.

[0393] Step 1603b: The UE performs subsequent SDT data transmission with the anchor base station.

[0394] Step 1604b: If the anchor base station determines to terminate the SDT in the process of performing the SDT, the anchor base station sends an RRC Cancel Request message to the serving base station. The RRC Cancel Request message includes an RRC Cancel message.

[0395] Step 1605b: The serving base station sends an RRC release message to the UE. The RRC release message is used to instruct the UE to terminate the SDT.

[0396] Step 1606b: The UE stops the SDT timer.

[0397] Step 1607b: The serving base station sends an RRC release complete message to the anchor base station.

[0398] It should be noted that the solutions shown in Figures 16a and 16b are applicable to a scenario in which the anchor access network device decides to terminate the SDT during the process of executing the SDT. Also, when the serving access network device sends an RRC message to the anchor access network device to request the establishment of a transmission link for the SDT, the anchor access network device may actively decide to terminate the SDT because the anchor access network device does not meet the requirements for the SDT (for example, when congestion occurs or the load exceeds a threshold). In this case, the procedure for the anchor access network device to actively terminate the SDT includes the above-mentioned steps 1604a to 1606a. For details, please refer to the related description above. The details will not be described again here.

[0399] Optionally, in this embodiment of the present application, if the serving access network device is different from the anchor access network device, when the anchor access network device terminates the SDT because the anchor access network device does not meet the SDT requirements, the anchor access network device may transition the anchor to the serving access network device after terminating the SDT to switch the core network channel from the anchor access network device to the current serving access network device, and transition the anchor to the serving access network device so that the serving access network device becomes the anchor access network device. Based on this solution, it is possible to prevent SDT delays caused by the anchor access network device. After the anchor transition, the terminal device can perform SDT with the current serving access network device (which is also the anchor access network device) to ensure that the subsequent SDT is performed smoothly.

[0400] Optionally, after receiving the first RRC message, the serving access network device may perform signaling interaction with the anchor access network device to establish a transmission link for the SDT. As shown in Figure 17, the procedure for establishing a transmission link for the SDT may include the following steps:

[0401] Step 1701: The serving access network device sends an eighth RRC message to the anchor access network device. Accordingly, the anchor access network device receives the eighth RRC message from the serving access network device. The eighth RRC message is used to instruct the establishment of an SDT.

[0402] Optionally, the eighth RRC message may be a UE context acquisition request message or a message similar to a UE context acquisition request message.

[0403] Optionally, the eighth RRC message may include a transmission instruction, where the transmission instruction is used to instruct the terminal device to request to perform SDT. For example, the transmission instruction may be an SDT instruction.

[0404] Optionally, the eighth RRC message may further include a MAC locale identifier (MAC LCID) of a media access control (MAC) layer protocol data unit (PDU), where the MAC LCID may be the MAC LCID of the first SDT data packet received by the serving access network device, and the MAC LCID may identify an SDT bearer.

[0405] Step 1702: The anchor access network device sends a ninth RRC message to the serving access network device. Accordingly, the serving access network device receives the ninth RRC message from the anchor access network device. The ninth RRC message is a response message to the eighth RRC message, and is used to instruct the anchor access network device to receive address information of the SDT data.

[0406] Optionally, the eighth RRC message is a UE context acquisition request message, and the ninth RRC message may be a UE context acquisition response message.

[0407] Optionally, the ninth RRC message may include one and / or multiple sets of information element TNL (this information element) addresses for the anchor access network device to receive SDT bearers, where the TNL addresses include a transport layer internet protocol (IP) address and a GTP (GPRS tunneling protocol) tunnel endpoint identifier (TEID) GTP-TEID, and different TNL addresses correspond to different SDT bearers.

[0408] Optionally, the ninth RRC message may further include a portion of the UE context. For example, the portion of the UE context may include radio link control (RLC) layer configuration information for one or more sets of SDT bearers and QoS parameters for one or more sets of SDT bearers. The QoS parameters may include, but are not limited to, the following information: 5G QoS identifier (5G QI), allocation and retention priority (ARP), packet delay budget (PDB), packet error rate (PER), or maximum data burst volume.

[0409] Optionally, the 9th RRC message further includes a PDU session identifier of the SDT bearer and / or an LCID of the SDT bearer, where the SDT bearer and the LCID have a one-to-one mapping relationship.

[0410] Optionally, the ninth RRC message may further include an indication flag indicating whether the serving access network device can reject the subsequent SDT of the terminal device. In this embodiment of the present application, if the indication flag indicates that the serving access network device can reject the subsequent SDT of the terminal device in the process of executing the SDT, if the serving access network device cannot execute the subsequent SDT for some reason, the serving access network device can directly reject the subsequent SDT by sending a third RRC message. However, if the indication flag indicates that the serving access network device cannot reject the subsequent SDT of the terminal device in the process of executing the SDT, if the serving access network device cannot execute the subsequent SDT for some reason, the serving access network device needs to send a fourth RRC message to the anchor access network device to request the anchor access network device to send a second RRC message to terminate the subsequent SDT.

[0411] Step 1703: The serving access network device sends a tenth RRC message to the anchor access network device. Thus, the anchor access network device receives the tenth RRC message from the serving access network device. The tenth RRC message is used to instruct the serving access network device to receive address information of the SDT data.

[0412] Optionally, the tenth RRC message may be an Xn address indication message or a message similar to an Xn address indication.

[0413] Optionally, the tenth RRC message may include one or more sets of TNL addresses for the serving access network device to receive the SDT bearer.

[0414] Optionally, if the first RRC message received by the serving access network device includes a first SDT data packet, the serving access network device may transmit the first SDT data packet in a tenth RRC message, thereby saving signaling resources and improving data transmission efficiency.

[0415] After the above steps 1701 to 1703, the serving access network device and the anchor access network device have successfully established a transmission link for SDT, and the terminal device can perform subsequent SDT data packet transmission with the anchor access network device.

[0416] After the transmission link for the SDT is established, upon receiving uplink data of the SDT bearer, the serving access network device may map the LCID in the MAC packet header of the SDT data packet to the TNL address provided by the anchor access network device, encapsulate the data packet into a GTP packet, and send the GTP packet to the anchor access network device. Upon receiving downlink data of the SDT bearer from the anchor access network device, the downlink data may be forwarded to the terminal device based on the TNL address.

[0417] Optionally, the embodiment shown in Figure 17 may be implemented independently of any of the previous embodiments. Alternatively, the embodiment shown in Figure 17 may be combined with a previous embodiment to form a new embodiment. For example, the procedure for establishing the SDT transmission link in step 1402a, step 1402b, step 1502a, step 1402b, step 1602a, or step 1602b above may be shown in steps 1701 to 1703.

[0418] For example, the data transmission method shown in Figure 14b is used as an example. As shown in Figure 18, when step 1402 is performed using the procedure shown in steps 1701 to 1703, assuming that the eighth RRC message is a UE context acquisition request message, the ninth RRC message is a UE context acquisition response message, and the tenth RRC message is an Xn address indication message, the data transmission method can include the following steps:

[0419] Step 1801: The UE sends an RRC resume request message to a serving base station, which is used to request the execution of an SDT.

[0420] Step 1802: The serving base station sends a UE context acquisition request message to the anchor base station. The UE context acquisition request message is used to instruct the anchor base station to perform SDT.

[0421] Step 1803: The anchor base station sends a UE context acquisition response message to the serving base station, where the UE context acquisition response message includes address information of the anchor base station for receiving SDT data.

[0422] Step 1804: The serving base station sends an Xn address indication message to the anchor base station, where the Xn address indication message includes address information for the serving base station to receive the SDT data.

[0423] Step 1805: The serving base station sends a first SDT data packet carried in an RRC resume request message to the anchor base station.

[0424] Step 1806: The UE performs subsequent SDT data transmission with the anchor base station.

[0425] Step 1807: If the serving base station does not meet the requirements of the SDT, the serving base station sends an RRC Release Request message to the anchor base station.

[0426] Step 1808: The anchor base station sends an RRC Cancellation Response message to the serving base station, which carries the RRC Cancellation message.

[0427] Step 1809: The serving base station sends an RRC Cancel message to the UE, which is used to instruct the terminal device to terminate the SDT.

[0428] Step 18010: The UE stops the SDT timer.

[0429] Step 18011: The serving base station sends an RRC release complete message to the anchor base station.

[0430] In addition, in the embodiment of the above-mentioned method, the processor 701 of the communication device 70 shown in Figure 7 may call application code stored in memory 704 to instruct the serving access network device to perform an operation of the serving access network device, the processor 701 of the communication device 70 shown in Figure 7 may call application code stored in memory 704 to instruct the anchor access network device to perform an operation of the anchor access network device, and the processor 701 of the communication device 70 shown in Figure 7 may call application code stored in memory 704 to instruct the terminal device to perform an operation of the terminal device.

[0431] It will be appreciated that in each of the above-described embodiments, the methods and / or steps implemented by the target node may be implemented by components (e.g., chips or circuits) available at the target node.

[0432] Optionally, embodiments of the present application further provide a communication device, which is configured to implement the various methods described above. The communication device may be a target node in the above-described method embodiments, or a device including the above-described target node, or a component usable in the target node. To implement the aforementioned functions, it can be understood that the communication device includes corresponding hardware structures and / or software modules that perform the functions. Those skilled in the art should easily recognize that the present application can be implemented by hardware or a combination of hardware and computer software, in combination with the example units and algorithm steps described in the embodiments disclosed herein. Whether the functions are implemented by hardware or hardware driven by computer software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered to go beyond the scope of the present application.

[0433] In the embodiments of the present application, the division of the communication device into functional modules may be performed according to the above-described method embodiments. For example, the functional module division may be based on corresponding functions, or two or more functions may be integrated into one processing module. The integrated module may be implemented in the form of hardware or in the form of a software functional module. It should be noted that in the embodiments of the present application, the module division is an example and is merely a logical functional division. Other division methods may be used in actual implementation.

[0434] 19 is a schematic diagram of the structure of a communication device 190. The communication device 190 includes a transceiver module 1901. The transceiver module 1901 is also called a transceiver unit that realizes transmitting and receiving functions. For example, the transceiver module may be a transceiver circuit, a transceiver machine, a transceiver, or a communication interface. Optionally, the communication device 190 may further include a processing unit 1902.

[0435] For example, the communication device 190 is a serving access network device in the above method embodiment.

[0436] The transceiver module 1901 may be configured to receive a first RRC message from the terminal device, where the first RRC message is used to establish an SDT. If the serving access network device does not meet the requirements of the SDT, the transceiver module 1901 may be further configured to send a second RRC message or a third RRC message to the terminal device, where the second RRC message is used to instruct the terminal device to terminate the SDT, and the third RRC message is used to instruct the serving access network device to refuse to execute the SDT.

[0437] Optionally, the serving access network device is not an anchor access network device. The transceiver module 1901 may be further configured to send a fourth RRC message to the anchor access network device before sending the second RRC message to the terminal device, where the fourth RRC message is used to request the anchor access network device to send the second RRC message. Further, the transceiver module 1901 may be further configured to receive a fifth RRC message from the anchor access network device, where the fifth RRC message is a response message to the fourth RRC message and includes the second RRC message.

[0438] Optionally, if the serving access network device determines in the process of performing the SDT that it does not meet the requirements of the SDT, the fifth RRC message may further be used to instruct the serving access network device to delete the context of the terminal device. The processing module 1902 may be configured to delete the locally stored context of the terminal device.

[0439] Optionally, if the serving access network device determines that the requirements of the SDT are not met in the process of performing the SDT, after sending a third RRC message to the terminal device, the transceiver module 1901 may be configured to send a sixth RRC message to the anchor access network device, where the sixth RRC message is used to instruct the anchor access network device to cancel the SDT.

[0440] For example, the communication device 190 is an anchor access network device in the above method embodiment.

[0441] The transceiver module 1901 may be configured to receive a fourth RRC message from the serving access network device, where the fourth RRC message is used to request the anchor access network device to send a second RRC message. Further, the transceiver module 1901 may be further configured to send a fifth RRC message to the serving access network device, where the fifth RRC message includes the second RRC message, where the second RRC message is used to instruct the terminal device to terminate the SDT.

[0442] Optionally, the fourth RRC message includes any one of a request indication, a redirect indication, or a cell reselection indication, where the request indication is used to request the anchor access network device to send the second RRC message, the redirect indication is used to instruct the serving access network device to recommend the terminal device to perform redirection, and the cell reselection indication is used to instruct the serving access network device to recommend the terminal device to perform cell reselection. The processing module 1902 may be further configured to determine that the fifth RRC message includes the second RRC message according to the request indication, the redirect indication, or the cell reselection indication.

[0443] Optionally, if the second RRC message includes the first redirection parameter, the fourth RRC message may further include the second redirection parameter. The processing module 1902 may be further configured to determine the first redirection parameter based on the second redirection parameter. If the second RRC message includes the first cell reselection priority parameter, the fourth RRC message may further include a second cell reselection priority parameter. The processing module 1902 may be further configured to determine the first cell reselection priority parameter based on the second cell reselection priority parameter.

[0444] Optionally, the fourth RRC message may further include a waiting time indication, and the processing module 1902 may be further configured to determine the waiting time according to the waiting time indication.

[0445] Optionally, the fourth RRC message further includes the first SDT data packet. The transceiver module 1901 may be further configured to transmit the first SDT data packet to a user plane network element.

[0446] For example, the communication device 190 is another anchor access network device in the above method embodiment.

[0447] The transceiver module 1901 may be configured to receive a sixth RRC message from the serving access network device, where the sixth RRC message is used to instruct the anchor access network device to cancel the SDT. The processing module 1902 may be configured to suspend a context of the terminal device performing the SDT based on the sixth RRC message.

[0448] For example, the communication device 190 is yet another anchor access network device in the above method embodiment.

[0449] The processing module 1902 may be configured to determine to terminate the SDT. The transceiver module 1901 may be configured to send a seventh RRC message to the serving access network device, where the seventh RRC message includes a second RRC message, and the second RRC message is used to instruct the terminal device to terminate the SDT.

[0450] For example, the communication device 190 is a terminal device in the above method embodiment.

[0451] The transceiver module 1901 may be configured to send a first RRC message from the terminal device to the serving access network device, where the first RRC message is used to establish the SDT. The processing module 1902 may be configured to stop the SDT timer upon receiving a second or third RRC message from the serving access network device. The second RRC message is used to instruct the terminal device to terminate the SDT, and the third RRC message is used to instruct the serving access network device to refuse to execute the SDT.

[0452] Optionally, upon receiving the third RRC message, the processing module 1902 may be further configured to notify upper layers of an SDT failure and restart an RNA timer, where the RNA timer is used to indicate that the terminal device is in an RRC inactive state.

[0453] Optionally, when receiving the second RRC message, the processing module 1902 may be further configured to notify upper layers of the SDT end.

[0454] Optionally, the second RRC message may include a suspend configuration, and the processing module 1902 may be further configured to suspend the context of the terminal device and restart the RNA timer.

[0455] Optionally, after the terminal device sends the first RRC message, the processing module 1902 may be further configured to start the SDT timer and pause the RNA timer.

[0456] Optionally, if untransmitted SDT data packets exist in the buffer of the terminal device, the processing module 1902 may be further configured to ignore the waiting time, perform redirection based on the first redirection parameter, and trigger SDT in the first cell to transmit the untransmitted SDT data packets in the buffer, where the first cell is the serving cell after the terminal device performs redirection.

[0457] Optionally, if untransmitted SDT data packets exist in the buffer of the terminal device, the processing module 1902 may be further configured to ignore the waiting time, perform cell reselection based on the first cell reselection priority parameter, and trigger SDT in the second cell to transmit the untransmitted SDT data packets in the buffer, where the second cell is the serving cell after the cell reselection is performed.

[0458] It should be noted that all relevant contents of the steps in the above method embodiments may be cited in the functional descriptions of the corresponding functional modules, and details will not be described here. The communication device 190 provided in this embodiment can implement the above data transmission method, so please refer to the above method embodiments for the technical effects that the communication device can achieve, and details will not be described again here.

[0459] Optionally, the serving access network device, the anchor access network device, or the terminal device in the embodiments of the present application are also called communication devices, and may be general-purpose devices or dedicated devices, which are not specifically limited in the embodiments of the present application.

[0460] In this embodiment, communication device 190 is presented by dividing the communication device 190 into functional modules. A "module," as used herein, may refer to a specific ASIC, circuitry, a processor and memory executing one or more software or firmware programs with the memory, integrated logic circuitry, and / or other components capable of providing the aforementioned functionality. In a simple embodiment, those skilled in the art will appreciate that communication device 190 may take the form of communication device 70 shown in FIG. 7.

[0461] For example, the processor 701 of the communication device 70 shown in FIG. 7 may invoke computer-executable instructions stored in the memory 704 to enable the communication device 70 to perform the data transmission method of the method embodiments described above.

[0462] Specifically, the functions / implementation processes of transceiver module 1901 and processing module 1902 in Fig. 19 may be implemented by processor 701 in communication device 70 in Fig. 7 by calling computer-executable instructions stored in memory 704. Also, processor 701 of communication device 70 shown in Fig. 7 may implement the functions / implementation processes of processing module 1902 in Fig. 19 by calling computer-executable instructions stored in memory 704, and the functions / implementation processes of transceiver module 1901 in Fig. 19 may be implemented by communication interface 703 of communication device 70 shown in Fig. 7.

[0463] The communication device 190 provided in this embodiment can implement the above-mentioned data transmission method, so for the technical effects that the communication device can achieve, please refer to the above-mentioned method embodiments, and the details will not be described again here.

[0464] It should be understood that the sequence numbers of the above processes do not refer to the order of execution in various embodiments of the present application, and the execution sequence of the processes should be determined according to the functions and internal logic of the processes, and should not be considered as a limitation on the implementation process of the embodiments of the present invention.

[0465] Those skilled in the art may recognize, with reference to the examples described in the embodiments disclosed herein, that the units and algorithms may be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be considered to go beyond the scope of this application.

[0466] Those skilled in the art can clearly understand that for convenience and simplicity of description, the specific operation processes of the above-mentioned systems, devices and units can be referred to the corresponding processes in the above-mentioned method embodiments, and the details will not be described again here.

[0467] It should be understood that in some embodiments provided herein, the disclosed systems, devices, and methods may be implemented in other ways. For example, the described device embodiments are merely examples. For example, the unit division is merely a logical functional division, and other division methods may be used in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some functions may be omitted or not performed. Furthermore, the shown or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. Indirect couplings or communication connections between devices or units may be implemented in an electrical, mechanical, or other form.

[0468] The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, and may be located in one place or distributed across multiple network units. Some or all of the units may be selected based on actual needs to achieve the purpose of the solution of the embodiment.

[0469] Furthermore, the functional units in the embodiments of the present application may be integrated into one processing unit, or each of the units may exist physically alone, or two or more units may be integrated into one unit.

[0470] All or part of the above-described embodiments may be implemented using software, hardware, firmware, or any combination thereof. When a software program is used to implement an embodiment, all or part of the embodiment may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the procedures or functions according to the embodiments of the present invention are generated. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or another programmable device. The computer instructions may be stored on a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, radio, or microwave) methods. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, or a magnetic tape), an optical medium (e.g., a DVD), a semiconductor medium (e.g., a solid-state disk (SSD)), etc.

[0471] As used herein, the terms "component," "module," "system," etc. are intended to refer to computer-related entities, which may be hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and / or a computer. For example, both an application running on a computing device and the computing device may be a component. One or more components may reside within a process and / or thread of execution, and a component may be located on one computer and / or distributed between two or more computers. Furthermore, these components may execute from various computer-readable media on which various data structures reside. These components may communicate in a local and / or remote process manner, such as based on signals comprising one or more data packets (e.g., data from one component interacting with another component in a local or distributed system and / or interacting with another system using signals over a network such as the Internet).

[0472] This application presents aspects, embodiments, or features related to systems that may include multiple devices, components, modules, etc. It is to be recognized and understood that each system may include additional devices, components, modules, etc. and / or may not include all of the devices, components, modules, etc. discussed with reference to the accompanying drawings. Furthermore, combinations of these solutions may be used.

[0473] Furthermore, the term "for example" in the embodiments herein is used to denote example, illustration, or explanation. Any embodiment or design described herein as "example" is not to be described as preferred or advantageous over other embodiments or design aspects. Rather, use of the term "for example" is intended to present concepts in a particular way.

[0474] In the embodiments of the present application, the terms information, signal, message, and channel may be used interchangeably. It should be noted that when the difference between them is not emphasized, their meanings are consistent. It should be noted that the terms "of," "corresponding," and "corresponding" may be used interchangeably, but when the difference between them is not emphasized, their meanings are consistent. The terms "system" and "network" may be used interchangeably, but when the difference between them is not emphasized, their meanings are consistent. For example, a "communication network" is also called a "communication system."

[0475] The network architectures and service scenarios described in the embodiments of the present application are intended to more clearly describe the technical solutions of the embodiments of the present application, and do not limit the technical solutions described in the embodiments of the present application. Those skilled in the art can understand that with the evolution of network architectures and the emergence of new service scenarios, the technical solutions provided in the embodiments of the present application can also be applied to solve similar technical problems.

[0476] The above description is merely a specific implementation of the present application and is not intended to limit the scope of protection of the present application. Any modifications or replacements that are readily conceived by those skilled in the art within the technical scope disclosed in the present application should be embraced within the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. A data transmission method applied to a serving access network device, the method comprising: receiving a first radio resource control (RRC) message from a terminal device, the first RRC message being used to establish a small data transmission (SDT); sending a third RRC message to the terminal device, the third RRC message being used to indicate that the SDT has been rejected by the serving access network device; Including, the third RRC message includes a waiting time, the waiting time indicating a period of time that the terminal device waits before initiating a next communication connection; If the serving access network device does not meet the requirements of the SDT in the process of executing the SDT, after sending the third RRC message to the terminal device, the method includes: sending a sixth RRC message to an anchor access network device, the sixth RRC message being used to instruct the anchor access network device to cancel the SDT; The method further comprises:

2. The step of transmitting a third RRC message to the terminal device includes: If the serving access network device does not meet the requirements of the SDT, sending the third RRC message to the terminal device; The serving access network device does not meet the requirements of the SDT, 2. The method of claim 1, wherein when the first RRC message is received, the serving access network device does not support the SDT, congestion occurs in the serving access network device, or a load on the serving access network device is greater than a threshold.

3. The step of transmitting a third RRC message to the terminal device includes: If the serving access network device does not meet the requirements of the SDT, sending the third RRC message to the terminal device; The serving access network device does not meet the requirements of the SDT, The method of claim 1 , wherein the process of performing the SDT includes: congestion occurring in the serving access network device; or a load on the serving access network device being greater than a threshold.

4. A data transmission method applied to an anchor access network device, the method comprising: establishing a link for small data transmission (SDT) with a serving access network device; receiving a sixth Radio Resource Control (RRC) message from the serving access network device, the sixth RRC message being used to instruct the anchor access network device to cancel the SDT; Including, The sixth RRC message is sent after the serving access network device sends a third RRC message to the terminal device in response to not meeting the requirements of the SDT in the process of executing the SDT, the third RRC message being used to indicate that the SDT has been rejected by the serving access network device and including a waiting time, the waiting time indicating a period of time the terminal device waits before initiating a next communication connection.

5. The serving access network device does not meet the requirements of the SDT in the process of executing the SDT, The method of claim 4 , comprising: congestion occurring at the serving access network device or a load on the serving access network device being greater than a threshold.

6. A data transmission method applied to a terminal device, the method comprising: sending a first radio resource control (RRC) message to a serving access network device, the first RRC message being used to establish a small data transmission (SDT); Stopping an SDT timer when a second RRC message is received from the serving access network device, the second RRC message being used to instruct the terminal device to terminate the SDT; Including, the second RRC message includes a waiting time, the waiting time indicating a period of time the terminal device waits before initiating a next communication connection; If there are untransmitted SDT data packets in the buffer of the terminal device, the method includes: ignoring the waiting time, performing a redirection based on a first redirection parameter included in the second RRC message, and triggering an SDT in a first cell to transmit the untransmitted SDT data packets in the buffer, the first cell being a serving cell after the terminal device has performed the redirection; The method further comprises:

7. The method of claim 6 , wherein the second RRC message is an RRC Cancel message.

8. When the second RRC message is received, the method comprises: The method of claim 6, further comprising the step of notifying an upper layer of the SDT termination.

9. If the second RRC message includes a suspend configuration, the method further comprises: The method of claim 8 , further comprising suspending the context of the terminal device and restarting an RNA timer.

10. After the terminal device transmits the first RRC message, the method includes: The method of claim 6 , further comprising starting the SDT timer.

11. A data transmission method applied to a terminal device, the method comprising: sending a first radio resource control (RRC) message to a serving access network device, the first RRC message being used to establish a small data transmission (SDT); stopping an SDT timer when a second RRC message is received from the serving access network device, the second RRC message being used to instruct the terminal device to terminate the SDT; Including, the second RRC message includes a waiting time, the waiting time indicating a period of time the terminal device waits before initiating a next communication connection; If there are untransmitted SDT data packets in the buffer of the terminal device, the method includes: Ignoring the waiting time, performing cell reselection based on a first cell reselection priority parameter included in the second RRC message, and triggering SDT in a second cell to transmit the untransmitted SDT data packets in the buffer, wherein the second cell is a serving cell after the terminal device performs the cell reselection; The method further comprises:

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