WO2024093933A1

WO2024093933A1 - Data transmission method and communication apparatus

Info

Publication number: WO2024093933A1
Application number: PCT/CN2023/127839
Authority: WO
Inventors: 酉春华; 科齐奥尔戴维德; 阿鲁瓦利亚贾格迪普·辛格
Original assignee: 华为技术有限公司
Priority date: 2022-11-03
Filing date: 2023-10-30
Publication date: 2024-05-10
Also published as: CN118042634A

Abstract

The present application relates to the field of communications, and provides a data transmission method and a communication apparatus. In the method, a terminal is in an RRC inactive state; a first network device sends a paging message to the terminal, wherein the paging message comprises instruction information for instructing the terminal to initiate an SDT process; according to the instruction information, the terminal initiates, when a certain condition is met, a random access process by using a random access resource of a random access process comprising no uplink SDT data, and instructs, in the random access process, to the first network device that the terminal has initiated a SDT process, wherein the condition comprises that the terminal comprises no uplink SDT data or comprises no uplink SDT configuration; and in the SDT process comprising a first random access process, the first network device sends downlink data to the terminal. According to the method, a random access resource of a random access process comprising no uplink SDT data is shared to initiate a random access process of transmitting downlink data, thereby reducing the overhead of random access resources while implementing downlink SDT.

Description

Data transmission method and communication device

This application claims the priority of the Chinese patent application filed with the State Intellectual Property Office on November 3, 2022, with application number 202211374054.5 and application name “Data Transmission Method and Communication Device”, all contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of communication technology, and in particular to a data transmission method and a communication device.

Background technique

Small data transmission (SDT) refers to the transmission of short data bursts in the inactive state of radio resource control (RRC), without entering the RRC connected state. Random access (RA)-SDT is one of the solutions to implement SDT. In the inactive state, only RA-SDT initiated by the terminal is supported, that is, only uplink RA-SDT is supported. For downlink data initiated by the network, the terminal still needs to be converted to the RRC connected state for transmission, which will cause transmission delay of downlink data.

Summary of the invention

The present application provides a data transmission method and a communication device, which can realize downlink SDT while saving resource overhead.

In a first aspect, a data transmission method is provided, which can be executed by a terminal, or by a component of the terminal (such as a processor, a chip, or a chip system, etc.), or by a logic module or software that can implement all or part of the terminal functions. The terminal is currently in a radio resource control RRC inactive state.

The method includes: receiving a first paging message from a first network device, the first paging message including first indication information, the first indication information being used to indicate a terminal to initiate a small data transmission SDT process; according to the first indication information, when a first condition or a second condition is met, using a first random access resource to initiate a first random access process, and sending second indication information and third indication information to the first network device during the first random access process, the first condition including that the terminal has no uplink SDT data, the second condition including that there is no uplink SDT configuration, the first random access resource does not belong to a first resource set, the resources in the first resource set are random access resources for a random access process for sending uplink SDT data, the second indication information indicates that the terminal has initiated the SDT process, and the third indication information is used to request to restore an RRC connection; receiving downlink data from the first network device during the SDT process, the SDT process including the first random access process.

Optionally, the first random access process is a 4-step random access process or a 2-step random access process. Accordingly, downlink data may be sent in message 4 in the 4-step random access process, or downlink data may be sent in message B in the 2-step random access process. The second indication information and the third indication information may also be sent in message 4 in the 4-step random access process, or the second indication information and the third indication information may be sent in message A in the 2-step random access process.

In addition, exemplarily, for a 4-step random access process, the resources in the first resource set (or random access resources) may include a random access preamble and/or a time-frequency resource for sending the random access preamble. Exemplarily, for a 2-step random access process, the resources in the first resource set may refer to resources with more time domain and/or frequency domain resources.

Exemplarily, the first resource set may be configured by the first network device through system information.

According to the data transmission method provided by the present application, the terminal can determine that it is necessary to initiate an SDT process for downlink data according to the second indication information, and then determine the random access resources required to initiate the random access process according to whether the first condition or the second condition is met, and use the selected random access resources to initiate the random access process. Specifically, in a scenario where there is downlink SDT data (i.e., downlink data or downlink small data) and there is no uplink SDT data, or in a scenario where there is downlink SDT data and there is no uplink SDT configuration, the terminal can initiate a random access process by using the random access resources of the random access process that sends no uplink SDT data, that is, the terminal can initiate a random access process without uplink SDT data. In this way, on the one hand, by sharing the random access resources of the random access process without uplink SDT data to initiate a random access process that can transmit downlink SDT data, there is no need to configure dedicated random access resources for downlink SDT data, which can save the overhead of random access resources. On the other hand, for 4-step random access, the first network device can determine whether the terminal has uplink SDT data based on the random access resources used by the terminal to initiate the random access process. If there is no uplink SDT data, the first network device can allocate a smaller grant (authorization) to the terminal. Transmit message 3, thereby avoiding resource waste. For 2-step random access, since there is no uplink SDT data, the terminal can select a smaller grant (i.e., the first random access resource) to transmit message A, which can also avoid resource waste. In addition, by introducing the second indication information during the random access process, it can help the second network device determine to keep the terminal in the RRC inactive state, so that downlink data can be transmitted in the RRC inactive state.

In a possible implementation, the method also includes: based on the first indication information, when the first condition is not met, using the second random access resource to initiate a second random access process, and in the second random access process, sending uplink SDT data and third indication information to the first network device, wherein the second random access resource belongs to the first resource set; receiving downlink data from the first network device in the SDT process, and the SDT process includes the second random access process.

Optionally, the second random access process is a 4-step random access process or a 2-step random access process. Accordingly, the uplink data and the third indication information may be sent in message 3 of the 4-step random access process, and the downlink data may be sent in message 4; or, the uplink data and the third indication information may be sent in message A of the 2-step random access process, and the downlink data may be sent in message B.

Based on this solution, in the scenario where there is downlink SDT data and uplink SDT data, the terminal can initiate a random access process by using the random access resources of the random access process for sending uplink SDT data. In this way, by sharing the random access resources of the random access process with uplink SDT data to initiate a random access process that can transmit downlink SDT data, there is no need to configure a dedicated random access resource for the downlink SDT data, which can save the overhead of random access resources.

In a possible implementation manner, the first condition or the second condition also includes that the current signal quality of the terminal is greater than or equal to a first threshold.

Optionally, the signal quality may include reference signal receiving power (RSRP) and/or reference signal receiving quality (RSRQ).

Optionally, before receiving the first paging message from the first network device, the method further includes: receiving a first threshold from the first network device.

For example, the first network device may send the first threshold in system information or in an RRC release message.

Optionally, the first paging message may include a first threshold.

Based on this solution, if the current signal quality of the terminal is greater than or equal to the first threshold, it means that the current signal quality of the terminal is good, and the terminal can receive downlink data without switching to the RRC connected state. In order to inform the network side of this situation, the terminal can introduce the second indication information during the random access process, so that the network side can determine that it is not necessary to switch the terminal to the RRC connected state according to the second indication information, and continue to keep the terminal in the RRC inactive state.

In a possible implementation manner, message 3 or message A includes an RRC recovery request, and the RRC recovery request includes the second indication information and the third indication information.

In a possible implementation, message 3 or message A includes the second indication information and an RRC recovery request, and the RRC recovery request is the third indication information.

Optionally, the second indication information is one or more of the following: SDT auxiliary information, indication information indicating the initiation of the SDT process, current signal quality information of the terminal, a first medium access control control element (MAC CE), or a second MAC CE. The first MAC CE includes a first logical channel identifier indicating the initiation of the SDT process, and the second MAC CE is a configuration authorization confirmation (CG confirmation) MAC CE.

In a possible implementation manner, the method further includes: receiving an RRC release message from the first network device, where the RRC release message is used to instruct the terminal to remain in an RRC inactive state and terminate the SDT process.

In one possible implementation, the first network device is a first distributed unit (DU).

In a second aspect, a data transmission method is provided, which can be executed by a first network device, or by a component of the first network device (such as a processor, a chip, or a chip system, etc.), or by a logic module or software that can implement all or part of the functions of the first network device.

The method includes: sending a first paging message to a terminal, the terminal is currently in an RRC inactive state, the first paging message includes first indication information, the first indication information is used to indicate that the terminal initiates a small data transmission SDT process; receiving second indication information and third indication information from the terminal during a first random access process initiated by using a first random access resource, or receiving uplink SDT data and third indication information from the terminal during a second random access process initiated by using a second random access resource, wherein the first random access resource does not belong to a first resource set, the resources in the first resource set are random access resources for a random access process for sending uplink SDT data, the second random access resource belongs to the first resource set, and the second indication information indicates that the terminal has initiated SDT process, the third indication information is used to request to restore the RRC connection; in the SDT process, downlink data is sent to the terminal, and the SDT process includes the first random access process or the second random access process.

According to the data transmission method provided by the present application, if the first random access process initiated by the terminal is a 4-step random access process, the first network device can determine that the terminal has no uplink SDT data based on the first random access resource used by the terminal, so as to allocate a smaller grant (authorization) transmission message 3 to the terminal to avoid resource waste. Moreover, regardless of whether the first random access process is a 4-step random access process or a 2-step random access process, the first network device can determine to keep the terminal in an RRC inactive state based on the second indication information, and send downlink data to the terminal in the RRC inactive state to achieve downlink SDT. In addition, if the terminal initiates the second random access process, the first network device can also determine to keep the terminal in an RRC inactive state after receiving the uplink SDT data, and send downlink data to the terminal in the RRC inactive state to achieve downlink SDT.

In a possible implementation, before sending the first paging message to the terminal, the method further includes: sending a first threshold to the terminal, where the first threshold is used by the terminal to determine whether to initiate a first random access procedure or to initiate a second random access procedure.

That is, the first threshold is used by the terminal to determine whether to send the first random access procedure or initiate the second random access procedure.

Exemplarily, the first network device may send the first threshold in system information or an RRC release message.

In a possible implementation manner, the first paging message includes a first threshold.

In a possible implementation, the first random access process is a 4-step random access process, and message 3 in the 4-step random access process includes the second indication information and the third indication information; or, the first random access process is a 2-step random access process, and message A in the 2-step random access process includes the second indication information and the third indication information; or, the second random access process is a 4-step random access process, and message 3 in the 4-step random access process includes uplink SDT data and the third indication information; or, the second random access process is a 2-step random access process, and message A in the 2-step random access process includes uplink data and the third indication information.

In a possible implementation, for the first random access process, message 3 or message A includes an RRC recovery request, and the RRC recovery request includes the second indication information and the third indication information. Alternatively, for the first random access process, message 3 or message A includes the second indication information and the RRC recovery request, and the RRC recovery request is the third indication information, and the second indication information is one or more of the following: SDT auxiliary information, indication information indicating the initiation of the SDT process, the current signal quality information of the terminal, the first media access control control unit MAC CE, or the second MAC CE, the first MAC CE includes the first logical channel identifier indicating the initiation of the SDT process, and the second MAC CE is the configuration authorization confirmation MAC CE.

In a possible implementation manner, for the second random access process, message 3 or message A includes an RRC recovery request and uplink data, wherein the third indication information is the RRC recovery request.

In a possible implementation manner, the first network device is a first distributed unit DU.

In a possible implementation, before sending a first paging message to the terminal, the method also includes: receiving a second paging message from a first centralized unit (CU), the second paging message including fourth indication information, the fourth indication information indicating that the terminal initiates an SDT process; wherein, after receiving the second indication information and the third indication information from the terminal in a first random access process initiated using a first random access resource, the method also includes: sending a fifth indication information to the first CU, the fifth indication information indicating that the terminal has initiated the SDT process; or, after receiving uplink SDT data and the third indication information from the terminal in a second random access process initiated using a second random access resource, the method also includes: sending uplink SDT data to the first CU; wherein, in the SDT process, before sending downlink data to the terminal, the method also includes: receiving downlink data from the first CU.

This solution supports downlink SDT under the CU-DU architecture.

In one possible implementation, before sending a first paging message to the terminal, the method also includes: receiving a second paging message from a second network device, the second paging message including an identifier of the terminal and fourth indication information, the fourth indication information indicating that the terminal initiates an SDT process; and, during the SDT process, before sending downlink data to the terminal, the method also includes: sending a first request message to the second network device, the first request message being used to request the context of the terminal, and the first request message including fifth indication information, the fifth indication information indicating that the terminal has initiated the SDT process; receiving part or all of the context and downlink data of the terminal from the second network device.

On the third aspect, a data transmission method is provided, which can be executed by a second network device, or by a component of the second network device (such as a processor, chip, or chip system, etc.), or by a logic module or software that can implement all or part of the functions of the second network device.

The method includes: sending a second paging message to the first network device, the second paging message including the terminal identifier and a fourth indication information, the terminal is currently in a radio resource control RRC inactive state, the fourth indication information is used to instruct the terminal to initiate a small data transmission SDT process; a first request message is received from a first network device, the first request message is used to request the context of the terminal, and the first request message includes fifth indication information, and the fifth indication information indicates that the terminal has initiated the SDT process; according to the fifth indication information, part or all of the context of the terminal and the downlink data of the terminal are sent to the first network device.

According to the method provided in the present application, the second network device can indicate to the terminal through the first network device that the terminal has initiated an SDT process triggered by downlink data. The terminal can, based on the indication, indicate to the second network device through the first network device that the terminal has initiated the SDT process, so that the second network device can determine to maintain the RRC inactive state of the terminal and send downlink data to the terminal through the first network device.

In a fourth aspect, a data transmission method is provided, which can be executed by the first CU, or by a component of the first CU (such as a processor, a chip, or a chip system, etc.), or by a logic module or software that can implement all or part of the functions of the first CU.

The method includes: sending a second paging message to a first DU, the second paging message including fourth indication information, the fourth indication information being used to indicate that a terminal initiates a small data transmission SDT process, and the terminal is currently in an RRC inactive state; receiving fifth indication information from the first DU, the fifth indication information indicating that the terminal has initiated an SDT process; establishing a context of the terminal with the first DU according to the fifth indication information; and sending downlink data to the first DU during the SDT process.

According to the method provided in the present application, the first CU can trigger the first DU to instruct the terminal to initiate the SDT process by sending the fourth indication information to the first DU, so that the terminal can initiate the corresponding random access process according to the indication and corresponding conditions, and indicate to the first CU through the first DU during the random access process that the terminal has initiated the SDT process, so that the first CU can transmit downlink data during the SDT process.

In a possible implementation manner, the method further includes: sending indication information for releasing the context of the terminal to the first DU, where the indication information is used to instruct the terminal to remain in the RRC inactive state and terminate the SDT process.

In one possible implementation, before the first DU sends the second paging message, the method also includes: receiving a third paging message from the second CU, the third paging message including sixth indication information, and the sixth indication information is used to indicate that the terminal initiates an SDT process; and before sending downlink data to the first DU, the method also includes: sending seventh indication information to the second CU, the seventh indication information indicating that the terminal has initiated an SDT process; receiving part or all of the context and downlink data of the terminal from the second CU.

Based on this scheme, if the first CU is not the CU corresponding to the last service access network device of the terminal, the first CU can indicate to the CU corresponding to the last service access network device of the terminal (i.e., the second CU) that the terminal has initiated the SDT process, so that the second CU can determine to keep the terminal in an RRC inactive state and transmit downlink data during the SDT process.

In one possible implementation, before sending indication information for releasing the context of the terminal to the first DU, the method further includes: receiving context acquisition failure indication information from the second CU, wherein the context acquisition failure indication information indicates that the terminal remains in an RRC inactive state and terminates the SDT process.

In the fifth aspect, a data transmission method is provided, which can be executed by the second CU, or by a component of the second CU (such as a processor, a chip, or a chip system, etc.), or by a logic module or software that can implement all or part of the functions of the second CU.

The method includes: sending a paging message to the first CU, the third paging message includes sixth indication information, the sixth indication information is used to indicate that the terminal initiates an SDT process, and the terminal is currently in an RRC inactive state; receiving seventh indication information from the first CU, the seventh indication information indicating that the terminal has initiated an SDT process; according to the seventh indication information, sending part or all of the context and downlink data of the terminal to the first CU. According to the method provided in the present application, in a scenario where the second CU is the CU corresponding to the last service access network device of the terminal and the first CU is the CU corresponding to the network access device accessed by the terminal, the second CU can instruct the terminal to initiate an SDT process triggered by downlink data. After the terminal initiates the SDT process, the first CU indicates to the second CU that the terminal has initiated the SDT process. The second CU can determine to keep the terminal in an RRC inactive state and transmit downlink data during the SDT process.

In a possible implementation manner, the method further includes: the second CU sends context acquisition failure indication information to the first CU, where the context acquisition failure indication information instructs the terminal to remain in the RRC inactive state and terminate the SDT process.

In a sixth aspect, a communication device is provided, comprising a module or unit for executing the method in the first aspect or any possible implementation manner of the first aspect.

In a seventh aspect, a communication device is provided, comprising: A module or unit of a method in .

In an eighth aspect, a communication device is provided, comprising a module or unit for executing the method in the third aspect or any possible implementation manner of the third aspect.

In a ninth aspect, a communication device is provided, comprising a module or unit for executing the method in the fourth aspect or any possible implementation manner of the fourth aspect.

In a tenth aspect, a communication device is provided, comprising a module or unit for executing the method in the fifth aspect or any possible implementation manner of the fifth aspect.

In the eleventh aspect, a communication device is provided, comprising a processor, the processor being coupled to a memory, the memory being used to store computer programs or instructions, and the processor being used to execute the computer programs or instructions stored in the memory to implement the method in the first aspect or any possible implementation of the first aspect.

In a possible implementation manner, the device further includes a memory coupled to the processor.

In a possible implementation, there are one or more processors and/or one or more memories.

In a possible implementation, the memory may be integrated with the processor, or the memory may be separately provided with the processor.

In a possible implementation manner, the device further includes a communication interface, and the processor is coupled to the communication interface.

In one implementation, the device is a terminal. Exemplarily, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the device is a chip of a terminal. Exemplarily, the communication interface may be an input/output interface.

In the twelfth aspect, a communication device is provided, including a processor, the processor is coupled to a memory, the memory is used to store computer programs or instructions, and the processor is used to execute the computer programs or instructions stored in the memory to implement: the method in the second aspect or any possible implementation of the second aspect.

In one implementation, the apparatus is a first network device. Exemplarily, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the device is a chip in the first network device. Exemplarily, the communication interface may be an input/output interface.

In the thirteenth aspect, a communication device is provided, including a processor, the processor is coupled to a memory, the memory is used to store computer programs or instructions, and the processor is used to execute the computer programs or instructions stored in the memory to implement: the method in the third aspect or any possible implementation of the third aspect.

In one implementation, the apparatus is a second network device. Exemplarily, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the device is a chip in the second network device. Exemplarily, the communication interface may be an input/output interface.

In the fourteenth aspect, a communication device is provided, including a processor, the processor is coupled to a memory, the memory is used to store computer programs or instructions, and the processor is used to execute the computer programs or instructions stored in the memory to implement: the method in the fourth aspect or any possible implementation of the fourth aspect.

In one implementation, the device is a first CU. Exemplarily, the communication interface may be a transceiver, or an input/output Outbound interface.

In another implementation, the device is a chip in the first CU. Exemplarily, the communication interface may be an input/output interface.

In the fifteenth aspect, a communication device is provided, including a processor, the processor is coupled to a memory, the memory is used to store computer programs or instructions, and the processor is used to execute the computer programs or instructions stored in the memory to implement: the method in the fifth aspect or any possible implementation of the fifth aspect.

In one implementation, the device is a second CU. Exemplarily, the communication interface may be a transceiver, or an input/output interface.

In another implementation, the device is a chip in the second CU. Exemplarily, the communication interface may be an input/output interface.

In a sixteenth aspect, a processor is provided, comprising: an input circuit, an output circuit, and a processing circuit. The processing circuit is used to receive a signal through the input circuit and transmit a signal through the output circuit, so that the processor executes the method in any one of the above aspects or any possible implementation of any one of the aspects.

In the specific implementation process, the above-mentioned processor can be a chip, the input circuit can be an input pin, the output circuit can be an output pin, and the processing circuit can be a transistor, a gate circuit, a trigger, and various logic circuits. The input signal received by the input circuit can be, for example, but not limited to, received and input by a receiver, and the signal output by the output circuit can be, for example, but not limited to, output to a transmitter and transmitted by the transmitter, and the input circuit and the output circuit can be the same circuit, which is used as an input circuit and an output circuit at different times. This application does not limit the specific implementation of the processor and various circuits.

In the seventeenth aspect, a communication system is provided, comprising the aforementioned terminal, the first network device, and/or the second network device, or comprising the aforementioned terminal, the first network device, the first CU, and/or the second CU.

In the eighteenth aspect, a computer program product is provided, which includes: a computer program (also referred to as code, or instruction), which, when executed, enables a computer to execute a method in any one of the above aspects or any one of the possible implementations of any one of the aspects.

In the nineteenth aspect, a computer-readable storage medium is provided, which stores a computer program (also referred to as code, or instruction). When the computer program runs on a computer, the computer executes a method in any one of the above aspects or any possible implementation of any one of the aspects.

In the twentieth aspect, a chip is provided, comprising a processor for calling and running a computer program from a memory, so that a communication device equipped with the chip executes a method in any one of the above aspects or any possible implementation of any one of the aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the architecture of a mobile communication system provided by the present application;

FIG2 is a schematic diagram of a CU/DU separation architecture provided by the present application;

FIG3 is a schematic flow chart of a 4-step random access process provided by the present application;

FIG4 is a schematic flow chart of a two-step random access process provided by the present application;

FIG5 is a schematic flow chart of a data transmission method provided by the present application;

FIG6 is a schematic flow chart of a data transmission method provided by the present application;

FIG7 is a schematic flow chart of a data transmission method provided by the present application;

FIG8 is a schematic flow chart of a data transmission method provided by the present application;

FIG9 is a schematic flow chart of a data transmission method provided by the present application;

FIG10 is a schematic block diagram of a communication device provided in an embodiment of the present application;

FIG11 is a schematic block diagram of another communication device provided in an embodiment of the present application;

FIG12 is a schematic structural diagram of an example terminal provided in an embodiment of the present application;

FIG13 is a schematic structural diagram of an access network device provided in an embodiment of the present application;

Figure 14 is a schematic structural diagram of an access network device provided in an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

In the description of the present application, unless otherwise specified, "/" indicates that the objects associated before and after are in an "or" relationship, for example, A/B can represent A or B; "and/or" in the present application is only a kind of association relationship describing the associated objects, indicating that there can be three relationships, for example, A and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more than two. "At least one of the following" or its similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, c can be single or multiple. In addition, in order to facilitate the clear description of the technical solution of the embodiment of the present application, in the embodiment of the present application, the words "first" and "second" are used to distinguish the same or similar items with basically the same functions and effects. Those skilled in the art can understand that the words "first", "second", etc. do not limit the quantity and execution order, and the words "first", "second", etc. do not necessarily limit the differences.

It should be understood that in the present application, "in the case of", "if", "when", "if", and similar expressions can be used interchangeably.

The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: long term evolution (LTE) system, fifth generation (5G) mobile communication system, new radio (NR) and other mobile communication systems that may appear in the future.

FIG1 is a schematic diagram of the architecture of a mobile communication system provided by the present application. As shown in FIG1 , the mobile communication system 100 includes at least one terminal (e.g., the terminal 110 shown in FIG1 ) and at least one access network device (e.g., the access network device 120 shown in FIG1 ). The terminal 110 can communicate data with the access network device 120 through a wireless connection by accessing the access network device 120.

In some embodiments, the access network device 120 is not the access network device corresponding to the last serving cell of the terminal 110, or in other words, the access network device 120 is not the last serving access network device of the terminal 110, and the system 100 may further include an access network device corresponding to the last serving cell of the terminal 110, such as the access network device 130. In this scenario, the uplink/downlink data of the terminal 110 and the context of the terminal 110 may be exchanged between the access network device 120 and the access network device 130.

It should be understood that the system 100 may also include core network equipment, such as access and mobility management (AMF) network elements and user plane function network elements.

The terminal in the embodiment of the present application, such as terminal 110, is also called user equipment (UE), mobile station (MS), mobile terminal (MT), etc., which refers to a device that provides voice and/or data connectivity to a user. For example, the terminal can be a mobile phone, a tablet computer, a laptop computer, a PDA, a mobile internet device (MID), a wearable device, a virtual reality (VR) device, an augmented reality (AR) device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, etc.

The access network devices in the embodiments of the present application, such as access network devices 120 and access network devices 130, refer to radio access network (RAN) nodes (or devices) that connect a terminal to a wireless network, and may also be referred to as base stations or network devices. For example, the access network device may be an evolved NodeB (eNodeB), a transmission reception point (TRP), a next generation NodeB (gNB) in a 5G mobile communication system, a base station in a future mobile communication system or an access point (AP) in a WiFi system, a wireless controller in a cloud radio access network (CRAN) scenario, a relay station, an access point, a vehicle-mounted device, a wearable device, and access network devices in other communication systems that evolve in the future. The present application does not limit the specific technology and specific device form adopted by the access network device.

It should be understood that in the architecture shown in FIG1 , the access network device 120 and the access network device 130 may be access network devices of different network standards, for example, one of the access network device 120 and the access network device 130 may be an eNodeB and the other may be a gNB. The access network device 120 and the access network device 130 may also be access network devices of the same network standard, for example, both are gNBs.

FIG2 shows a schematic diagram of a CU/DU separation architecture. Referring to FIG2, in some network architectures, access network devices, such as The access network device 120 or the access network device 130 in Fig. 1 can be logically divided into a CU and one or more DUs. Each DU is connected to the CU respectively, for example, each DU can be connected to the CU via a FI logical interface.

Exemplarily, in one protocol stack division method, operations related to the radio link control (RLC) layer, the media access control (MAC) layer and the physical (PHY) layer are handled by the DU, and operations related to the service data adaptation protocol (SDAP) layer, the radio resource control (RRC) layer and the packet data convergence protocol (PDCP) layer are handled by the CU.

Before introducing the present application method, 4-step random access (4-step RACH) and 2-step random access (2-step RACH) are first introduced.

See Figure 3, which is a schematic diagram of the four-step random access process. As shown in Figure 3, the terminal sends message 1 (message 1, abbreviated as msg1) to the access network device. Message 1 is also the random access preamble. After the access network device detects the random access preamble, it returns a response message to the terminal, which is message 2. Message 2 contains the uplink resources allocated by the network side to the terminal. After receiving message 2, the terminal sends message 3 on the uplink resources indicated by message 2. If the access network device can correctly decode message 3, it returns message 4 to the terminal. Message 4 is used to notify the terminal that the competition is successful. After the above four steps, the random access process is successful.

With the introduction of new wireless terminal types such as machine type communication (MTC) and narrowband internet of things (NB-IoT), the number of terminals has increased exponentially. If all terminals use 4-step random access, it will cause the access network equipment to be overloaded. In addition, the delay of 4-step random access is also relatively long. In order to solve these problems, 2-step random access was introduced.

See FIG. 4, which is a schematic diagram of a two-step random access process. In the two-step random access process, the terminal carries both the random access preamble and data (i.e., preamble+data) in message A. The data part is usually an RRC message, such as an RRC recovery request. If there is no conflict between terminals, the access network device successfully decodes message A and returns message B to the terminal. Message B includes both a response to the random access preamble and a response to the data. Among them, the response to the random access preamble is also a random access response (RAR). The response to the data is usually an RRC message. The two parts of the response can be sent simultaneously or successively. The terminal can decode the two parts of the response independently. After receiving message B, the terminal learns that the random access is successful. If there is a conflict between terminals, the access network device may not be able to successfully decode the data in message A. At this time, the network device does not send message B to the terminal. After sending message A, the terminal waits for a time window. If message B is not received, it is considered that the random access has failed.

It should be understood that message A in the 2-step random access process may be message 1+message 3 in the 4-step random access process; and message B in the 2-step random access process may be message 2+message 4 in the 4-step random access process.

The terminal can transmit data in the RRC connected (RRC_CONNECTED) state or in the RRC inactive state. In the RRC inactive state, the access network device releases the air interface connection with the terminal, but maintains the connection between the access network device and the core network; and the access network device and the terminal respectively save the relevant context of the terminal (such as the air interface identifier of the terminal, the identifier of the serving cell, etc.), so that the air interface connection between the access network device and the terminal can be quickly restored through the RRC connection recovery process when needed.

In the RRC inactive state, the terminal can perform an uplink SDT process. In the uplink SDT solution based on random access, the terminal in the RRC inactive state can initiate the SDT process using resources such as message 3 of the 4-step random access or message A of the 2-step random access.

1. Uplink SDT based on 4-step random access

The network side can configure the random access resources (referred to as: the first resource set) of the random access process that can send uplink SDT data for the terminal. Under the condition that the SDT process triggered by the uplink SDT data is met, the terminal in the RRC inactive state can use the random access resources in the first resource set to send message 1. After the network side receives message 1, it can allocate a larger grant to the terminal in message 2. The terminal can transmit message 3 through the grant and carry the uplink SDT data in message 3. If the uplink SDT data is not fully transmitted in message 3, after the network side sends message 4, the terminal can continue to transmit the remaining uplink SDT data.

2. Uplink SDT based on 2-step random access

The network side can configure a first resource set for the terminal. Under the condition that the SDT process triggered by the uplink SDT data is satisfied, the terminal in the RRC inactive state can use the random access resources in the first resource set to send message A, and carry the uplink SDT data in message A. If the uplink SDT data is not fully transmitted in message A, after the network side sends message B, the terminal The end can also continue to transmit the remaining uplink SDT data.

In the above scheme, only SDT initiated by the terminal is supported in the inactive state, that is, only uplink SDT is supported. The downlink small data initiated by the network still needs to be transmitted after the terminal is converted to the RRC connection state, which will cause transmission delay of downlink small data.

In view of this, the present application provides a data transmission method, which can support downlink SDT in the RRC state. The solution provided by the present application is described in detail below in conjunction with the architectures shown in FIG1 and FIG2 .

It can be understood that any execution entity in the method provided in the present application, such as the first network device, the second network device, the first CU, the first DU, the second CU, the second DU or the terminal can also be replaced by a chip, a chip system, or a processor that supports the execution entity to implement the method, or it can be a logic module or software that can implement all or part of the functions of the execution entity.

Fig. 5 is a schematic flow chart of a data transmission method provided by the present application. The method 300 may include S310 to S330. In the method 300, it is assumed that the first network device is the last service access network device of the terminal, and the terminal is currently in an RRC inactive state.

S310: The first network device sends a first paging message to the terminal. Correspondingly, the terminal receives the first paging message from the first network device.

The first network device may send a first paging message to the terminal after receiving downlink data (i.e., downlink SDT data) sent by the core network device. The first paging message includes first indication information and an identifier of the terminal. The first indication information is used to indicate that the terminal initiates an SDT process, or the first indication information indicates that there is downlink SDT data. The identifier of the terminal may be an inactive radio network temporary identity (I-RNTI).

S320: The terminal initiates a first random access process using a first random access resource according to the first indication information when the first condition or the second condition is met, and sends second indication information and third indication information to the first network device during the first random access process.

After receiving the first paging message, the terminal can determine that an SDT process needs to be initiated or that there is downlink SDT data according to the first paging message. Then, the terminal determines whether the first condition or the second condition is met, and if the first condition or the second condition is met, the terminal uses the first random access resource to initiate the first random access process, and sends the second indication information and the third indication information to the first network device during the first random access process.

The first condition includes that the terminal has no uplink SDT data. That is, when the terminal has no uplink SDT data, the terminal can initiate the first random access process using the first random access resource.

The second condition includes no uplink SDT configuration, for example, the network side does not configure random access resources for uplink SDT for the terminal. That is, when the terminal does not have uplink SDT configuration, the terminal can initiate the first random access process using the first random access resource.

Among them, the first random access resource does not belong to the first resource set, and the resources in the first resource set are random access resources for the random access process of sending uplink SDT data. That is, when the terminal has no uplink SDT data, the terminal can use random access resources other than the first resource set (for example, the first random access resource) to initiate a random access process. When the terminal has uplink SDT data, the terminal can use random access resources in the first resource set (for example, the second random access resource described below) to initiate a random access process. Exemplarily, the random access resources may include a random access preamble and/or a time-frequency resource for sending a random access preamble. It should be understood that the random access resources may also include other resources, such as carrier resources, etc.

For 4-step random access, the first network device can determine whether the terminal has uplink SDT data based on the first random access resource used by the terminal to initiate the first random access process. If there is no uplink SDT data, the first network device can allocate a smaller grant to the terminal in message 2 to transmit message 3, which can improve resource utilization.

For 2-step random access, since there is no uplink SDT data, the terminal can select a smaller grant (ie, the first random access resource) to transmit message A, which can also improve resource utilization.

The second indication information indicates that the terminal has initiated the SDT process, and the third indication information is used to request restoration of the RRC connection.

Exemplarily, when the first random access procedure is a 4-step random access procedure, message 3 in the 4-step random access procedure may include second indication information and third indication information.

Exemplarily, when the first random access procedure is a 2-step random access procedure, message A in the 2-step random access procedure may include second indication information and third indication information.

S330: The first network device sends downlink data (ie, downlink SDT data) to the terminal during the SDT process. Accordingly, the terminal receives downlink data from the first network device during the SDT process. The SDT process includes a first random access process.

According to the second indication information, the first network device can learn that the first random access process is an SDT process triggered by downlink data, thereby determining to continue to keep the terminal in the RRC inactive state and send downlink data to the terminal in the inactive state. For example, the first network device can send downlink data in message 4. If only a part of the downlink data can be sent in message 4, the remaining downlink data can be sent after message 4. Alternatively, the first network device can send downlink data in message B. If only a part of the downlink data can be sent in message B, the remaining downlink data can be sent after message B.

It should be understood that during the SDT process, the terminal always remains in the RRC inactive state. In addition, the entire process from the terminal initiating the first random access process to the completion of the downlink data transmission can be called the SDT process. The completion of the downlink data transmission and the receipt of the RRC release message also means that the SDT process ends.

In summary, according to the data transmission method provided by the present application, in a scenario where there is downlink SDT data but no uplink SDT data, or in a scenario where there is downlink SDT data but no uplink SDT configuration, the terminal can initiate a random access process by using the random access resources of the random access process that sends no uplink SDT data, that is, the terminal can initiate a random access process without uplink SDT data. In this way, on the one hand, by sharing the random access resources of the random access process without uplink SDT data to initiate a random access process that can transmit downlink SDT data, there is no need to configure a dedicated random access resource for downlink SDT data, which can save the overhead of random access resources. On the other hand, for 4-step random access, the first network device can determine whether the terminal has uplink SDT data based on the random access resources used by the terminal to initiate the random access process. If there is no uplink SDT data, the first network device can allocate a smaller grant to the terminal to transmit message 3, thereby avoiding resource waste. For 2-step random access, since there is no uplink SDT data, the terminal can select a smaller grant (i.e., the first random access resource) to transmit message A, which can also avoid resource waste.

In addition, by introducing the second indication information in the random access process, the first network device can be helped to determine to keep the terminal in the RRC inactive state, so that downlink data can be transmitted in the RRC inactive state.

Optionally, the method may further include:

S340: When the first condition is not met, the terminal initiates a second random access process using a second random access resource, and sends uplink SDT data and third indication information to the first network device during the second random access process. Accordingly, the first network device receives the uplink SDT data and third indication information from the terminal during the second random access process.

That is, when the terminal has uplink SDT data, the terminal can initiate the second random access process using the second random access resource. It should be understood that it is assumed here that there is an uplink SDT configuration. The second random access resource belongs to the first resource set.

For 4-step random access, the first network device can determine that the terminal has uplink SDT data based on the second random access resource used by the terminal to initiate the second random access process. If there is uplink SDT data, the first network device can allocate a larger grant to the terminal in message 2 to transmit message 3, where message 3 includes uplink SDT data and third indication information.

For 2-step random access, since there is uplink SDT data, the terminal may select a larger grant (ie, the second random access resource) to transmit message A, wherein message A includes the uplink SDT data and the third indication information.

S350, the first network device sends downlink data (ie, downlink SDT data) to the terminal during the SDT process. Correspondingly, the terminal receives downlink data from the first network device during the SDT process. The SDT process includes a second random access process.

After receiving the uplink SDT data and the third indication information, the first network device determines to keep the terminal in the RRC inactive state, and can send the downlink data in the next downlink message. For example, the first network device can send the downlink data in message 4. If only a part of the downlink data can be sent in message 4, the remaining downlink data can be sent after message 4. Alternatively, the first network device can send the downlink data in message 2. If only a part of the downlink data can be sent in message 2, the remaining downlink data can be sent after message 2.

Optionally, the method may further include:

S360: The first network device sends an RRC release message to the terminal. Correspondingly, the terminal receives the RRC release message from the first network device.

The RRC release message is used to instruct the terminal to remain in the RRC inactive state and terminate the SDT process. The first network device may send the RRC release message to the terminal after sending the downlink data. After receiving the RRC release message, the terminal continues to remain in the RRC inactive state and terminates the SDT process.

Optionally, the first condition may further include: the current signal quality of the terminal is greater than or equal to a first threshold.

Similarly, the second condition may also include: the current signal quality of the terminal is greater than or equal to the first threshold.

Accordingly, before S310, the first network device may send the first threshold to the terminal. For example, the first network device may send the first threshold to the terminal via an RRC release message or a system message (eg, SIB1) sent before S310. For another example, the first network device may send the first threshold in a first paging message.

Exemplarily, the signal quality may be RSRP and/or RSRQ. For example, the terminal may measure the SSB of the first network device and obtain the current RSRP of the terminal through calculation.

Specifically, after the terminal receives the first paging message, if it is determined that the current signal quality of the terminal is greater than or equal to the first threshold and there is no uplink SDT data, or if it is determined that the current signal quality of the terminal is greater than or equal to the first threshold and there is no uplink SDT configuration, a first random access process can be initiated.

Exemplarily, the first threshold may be the same as or different from the signal quality threshold corresponding to the uplink SDT specified in the current protocol, and this application does not limit this.

Exemplarily, the second indication information and the third indication information described in S320 above may be carried by an RRC recovery request, and the RRC recovery request may be included in message 3 or message A.

For example, the RRC recovery request may include the third indication information, and the RRC recovery request may add a flag bit, and the information of the flag bit is the second indication information.

Exemplarily, the third indication information may be an RRC recovery request, and the second indication information may be another RRC information or MAC CE different from the RRC recovery request.

For example, the second indication information may be one or more of the following: SDT auxiliary information, indication information indicating initiation of the SDT process, current signal quality information of the terminal, a first MAC CE, or a second MAC CE. Among them, the first MAC CE includes a first logical channel identifier indicating initiation of the SDT process, and the second MAC CE is a configuration authorization confirmation MAC CE (CG confirmation MAC CE).

The SDT auxiliary information may implicitly indicate that the terminal has initiated the SDT process. Exemplarily, after the first network device sends the first paging message, it receives the SDT auxiliary information, which indicates that the terminal has initiated the SDT process.

The content of the indication information indicating initiation of the SDT process may be the same as the first indication information.

The current signal quality information of the terminal may be, for example, an RSRP value or an RSRP index.

The first MAC CE includes a first logical channel identifier, and the first logical channel identifier indicates that the terminal has initiated the SDT process. The first MAC CE may have only a header (subheader) and no payload (payload), and may also be called an empty MAC CE. The first logical channel identifier may be a special logical channel identifier, which may be newly allocated and different from the identifier of the existing MAC CE. The identifier may be carried in the header, so that the network device can determine, based on the logical channel identifier, that the MAC CE is used to indicate that the terminal has initiated the SDT process.

Under normal circumstances, CG confirmation MAC CE is only used in the connected state. If CG confirmation MAC CE is sent in the RRC inactive state, the CG confirmation MAC CE can indicate that the terminal has initiated the SDT process. This solution can save logical channel identifiers by reusing existing MAC CE.

Exemplarily, the second indication information described above in S340 may also be SDT auxiliary information, indication information indicating the initiation of the SDT process, current signal quality information of the terminal, the first MAC CE, or the second MAC CE.

In the method 300 described above, it is assumed that the first network device is the last service access network device of the terminal. In actual application scenarios, the first network device may not be the last service access network device of the terminal, and the first access network device may also adopt the CU-DU architecture. The data transmission methods in these scenarios are described below. It should be understood that the principle of any method in the methods 400 to 600 described below is similar to that of the method 300, and in any method below and the method 300, the same The terms or words have the same meanings, and the implementation methods of the same operations are also the same, and the methods described below will not be repeated.

FIG6 is a schematic flow chart of a data transmission method provided by the present application. The method 400 may include one or more steps from S401 to S411. In the method 400, it is assumed that the second network device is the last service access network device of the terminal, the first network device is the access network device currently accessed by the terminal, and the terminal is currently in an RRC inactive state. The second network device stores the context of the terminal.

S401: The second network device sends a second paging message to the first network device. Correspondingly, the first network device receives the second paging message from the second network device.

The second paging message includes the identifier of the terminal and fourth indication information. The fourth indication information is used to instruct the terminal to initiate an SDT process.

Optionally, the second paging message may include the first threshold.

S402: The first network device sends a first paging message to the terminal according to the second paging message. Correspondingly, the terminal receives the first paging message from the first network device.

According to the second paging message, the first network device may determine that the terminal needs to be paged and needs to trigger the terminal to initiate an SDT process, thereby generating a first paging message and carrying the identifier of the terminal and the first indication information in the first paging message.

Optionally, the first paging message may include a first threshold.

S403: The terminal initiates a first random access process using a first random access resource according to the first indication information when the first condition or the second condition is met, and sends second indication information and third indication information to the first network device during the first random access process. Accordingly, the first network device receives uplink SDT data and the third indication information from the terminal during the first random access process.

This step is the same as S320, and details may refer to S320.

Optionally, the method may further include:

S404: When the first condition is not met, the terminal initiates a second random access process using a second random access resource, and sends uplink SDT data and third indication information to the first network device during the second random access process. Accordingly, the first network device receives the uplink SDT data and third indication information from the terminal during the second random access process.

This step is the same as S340, and details may be referred to S340.

S405: The first network device sends a first request message to the second network device. Correspondingly, the second network device receives the first request message from the first network device.

The first request message is used to request the context of the terminal, and the first request message includes fifth indication information. The fifth indication information is used to instruct the terminal to initiate an SDT process.

For example, the first request message may be a retrieve UE context request message.

S406: The second network device sends part or all of the context of the terminal to the first network device according to the first request message. Correspondingly, the first network device receives part or all of the context of the terminal from the second network device.

For example, the second network device may send a retrieve UE context response message to the first network device, which may include part or all of the context of the terminal.

S407: The second network device determines to keep the terminal in an RRC inactive state according to the fifth indication information.

It should be understood that the present application does not limit the order between S406 and S407. For example, the two can be executed simultaneously, or S406 can be executed first and then S407, or S407 can be executed first and then S406.

S408: The second network device sends downlink data to the first network device. Correspondingly, the first network device receives the downlink data from the second network device.

S409: The first network device sends downlink data to the terminal.

If S403 is executed, the first network device may send downlink data to the terminal in the SDT process included in the first random access process. For details of this situation, please refer to S330.

If S404 is executed, the first network device may send downlink data to the terminal in the SDT process included in the second random access process. For details of this situation, please refer to S350.

S410: The second network device sends RRC release indication information to the first network device. Correspondingly, the first network device receives the RRC release indication information from the second network device.

After completing the SDT data transmission, the second network device determines to terminate the SDT process, and instructs the terminal to remain in the RRC inactive state and terminate the SDT process by sending RRC release indication information to the first network device.

For example, the RRC release indication information may be an RRC release message.

S411, the first network device sends an RRC release message to the terminal. This step may refer to S360.

According to the data transmission method provided by the present application, in a scenario where there is downlink SDT data but no uplink SDT data, or in a scenario where there is downlink SDT data but no uplink SDT configuration, the terminal can initiate a random access process by using the random access resources of the random access process that sends no uplink SDT data, that is, the terminal can initiate a random access process without uplink SDT data. In this way, on the one hand, by sharing the random access resources of the random access process without uplink SDT data to initiate a random access process that can transmit downlink SDT data, there is no need to configure a dedicated random access resource for downlink SDT data, which can save the overhead of random access resources. On the other hand, for 4-step random access, the first network device can determine whether the terminal has uplink SDT data based on the random access resources used by the terminal to initiate the random access process. If there is no uplink SDT data, the first network device can allocate a smaller grant to the terminal to transmit message 3, thereby avoiding resource waste. For 2-step random access, since there is no uplink SDT data, the terminal can select a smaller grant (i.e., the first random access resource) to transmit message A, which can also avoid resource waste.

In addition, by introducing the fifth indication information in the random access process, the second network device can be helped to determine to keep the terminal in the RRC inactive state, so that downlink data can be transmitted in the RRC inactive state.

7 is a schematic flow chart of a data transmission method provided by the present application. The method 500 may include one or more steps from S501 to S511. The first CU and the first DU in the method 500 are the CU and the DU of the first network device in the method 300, respectively, and the terminal is currently in an RRC inactive state.

S501: A first CU sends a second paging message to a first DU. Correspondingly, the first DU receives the second paging message from the first CU.

The first CU may send a second paging message to the first DU after receiving downlink data (ie, downlink SDT data) sent by the core network device, wherein the second paging message includes fourth indication information and the identifier of the terminal, and the fourth indication information indicates that the terminal has initiated the SDT process.

S502: The first DU sends a first paging message to the terminal.

Among them, the first paging message can refer to S310.

S503: The terminal initiates a first random access process using a first random access resource according to the first indication information in the first paging message when the first condition or the second condition is met, and sends second indication information and third indication information to the first DU during the first random access process.

This step is similar to S320, except that the first network device in S320 is replaced by the first DU.

S504: The first DU sends fifth indication information to the first CU. Correspondingly, the first CU receives the fifth indication information from the first DU.

The fifth indication information is used to instruct the terminal to initiate the SDT process.

For example, the first DU may send an initial UL RRC message transfer (initial UL RRC message transfer) message to the first CU, which may include fifth indication information.

S505: The first CU determines to keep the terminal in an RRC inactive state according to the fifth indication information.

It should be understood that S505 may also be executed between S506 and S508.

S506: The first CU sends a UE context setup request message to the first DU. Correspondingly, the first DU receives the UE context setup request message from the first CU.

The first DU may establish a context for the UE according to the UE context establishment request message.

S507, the first DU sends a UE context setup response message to the first CU. Correspondingly, the first CU receives the UE context setup response message from the first DU.

S508, the first CU sends downlink data (ie, downlink SDT data) to the first DU during the SDT process. Correspondingly, the first DU receives downlink data from the first CU during the SDT process. The SDT process includes a first random access process.

S509: The first DU sends downlink data to the terminal during the SDT process. Correspondingly, the terminal receives downlink data from the first DU during the SDT process.

For example, the first DU can send downlink data in message 4. If only a portion of the downlink data can be sent in message 4, the remaining The remaining downlink data may be sent after message 4. Alternatively, the first DU may send the downlink data in message B. If only a portion of the downlink data can be sent in message B, the remaining downlink data may be sent after message B.

Optionally, the method may further include:

S510, the first CU sends a UE context release command (UE context release command) to the first DU. Correspondingly, the first DU receives the UE context release command from the first CU.

After completing the SDT data transmission, the first CU determines to terminate the SDT process, and instructs the terminal to remain in the RRC inactive state and terminate the SDT process by sending a UE context release command to the first DU.

S511, the first DU sends an RRC release message to the terminal. Correspondingly, the terminal receives the RRC release message from the first DU.

The RRC release message is used to instruct the terminal to remain in the RRC inactive state and terminate the SDT process. After receiving the RRC release message, the terminal continues to remain in the RRC inactive state and terminates the SDT process.

Based on this method, downlink SDT based on random access can be implemented in a CU-DU separation architecture. This solution initiates a random access process that can transmit downlink SDT data by sharing the random access resources of the random access process without uplink SDT data. There is no need to configure dedicated random access resources for downlink SDT data, which can save the overhead of random access resources. On the other hand, for 4-step random access, the first CU can determine whether the terminal has uplink SDT data based on the random access resources used by the terminal to initiate the random access process. If there is no uplink SDT data, the first CU can allocate a smaller grant to the terminal to transmit message 3, thereby avoiding resource waste. For 2-step random access, since there is no uplink SDT data, the terminal can select a smaller grant (i.e., the first random access resource) to transmit message A, which can also avoid resource waste. In addition, by introducing the fourth indication information in the random access process, the first network device can be helped to determine to keep the terminal in an RRC inactive state, so that downlink data can be transmitted in an RRC inactive state.

Optionally, if the terminal determines that the first condition or the second condition is not met based on the first indication information, the second random access process may be initiated using the second random access resource, and uplink SDT data and third indication information may be sent to the first DU during the second random access process. Then, the first DU may send the uplink SDT data and indication information indicating the content indicated by the third indication information to the first CU. After the first CU receives the uplink SDT data and the indication information indicating the content indicated by the third indication information, it may determine to keep the terminal in an RRC inactive state. The operations thereafter may refer to the steps after S505, which will not be described in detail here.

FIG8 is a schematic flow chart of a data transmission method provided by the present application. The method 600 may include one or more steps of S601 to S616. In the method 600, the first CU and the first DU are the CU and DU of the first network device in the method 400, respectively, the second CU may be the CU of the second network device in the method 400, and the terminal is currently in an RRC inactive state.

S601: The second CU sends a third paging message to the first CU. Correspondingly, the first CU receives the third paging message from the second CU.

The second CU may send a third paging message to the first CU after receiving the downlink data sent by the core network device. The third paging message may include sixth indication information and the identifier of the terminal, wherein the sixth indication information is used to instruct the terminal to initiate an SDT process.

S602: The first CU sends a second paging message to the first DU. Correspondingly, the first DU receives a paging message from the second CU.

After receiving the third paging message, the first CU sends a second paging message to the first DU, and the second paging message may include fourth indication information and the identifier of the terminal, wherein the fourth indication information is used to instruct the terminal to initiate an SDT process.

S603 to S605 are the same as S502 to S504.

S606, the first CU sends seventh indication information to the second CU. Correspondingly, the second CU receives the seventh indication information from the first CU. The seventh indication information is used to instruct the terminal to initiate an SDT process.

For example, the first CU may send a retrieve UE context request message to the second CU, and the message may include the seventh indication information.

S607: The second CU determines to keep the terminal in an RRC inactive state according to the seventh indication information.

S608: The second CU sends part or all of the context of the terminal to the first CU. Accordingly, the first CU receives part or all of the context of the terminal from the second CU.

For example, the second CU may send a partial UE context transfer message to the first CU. The message may include part or all of the context of the terminal, such as the RLC configuration.

It should be understood that if the second CU determines not to change the anchor point according to the seventh indication information, the first CU continues to maintain the context of the terminal and can send part of the context of the terminal to the first CU. If the second CU determines to change the anchor point according to the seventh indication information, the context of the terminal can be handed over to the first CU for maintenance.

It should be understood that the present application does not limit the order between S607 and S608.

S609, the first CU sends a UE context setup request message to the first DU. Correspondingly, the first DU receives the UE context setup request message from the first CU.

S610, the first DU sends a UE context setup response message to the first CU. Correspondingly, the first CU receives the UE context setup response message from the first DU.

S611: The second CU sends downlink data of the terminal to the first CU.

S612: The first CU sends the downlink data to the first DU.

S613: The first DU sends the downlink data to the terminal.

S614, the second CU sends a retrieve UE context failure message to the first CU.

After completing the SDT data transmission, the second CU determines to terminate the SDT process, and instructs the terminal to remain in the RRC inactive state and terminate the SDT process by sending a UE context failure message to the first CU.

S615: The first CU sends a UE context release command (UE context release command) to the first DU. Correspondingly, the first DU receives the UE context release command from the first CU.

The UE context release command instructs the terminal to remain in the RRC inactive state and terminate the SDT process.

S616: The first DU sends an RRC release message to the terminal. Correspondingly, the terminal receives the RRC release message from the first DU.

Based on this method, downlink SDT based on random access can be implemented in a CU-DU separation architecture. This solution initiates a random access process that can transmit downlink SDT data by sharing the random access resources of the random access process without uplink SDT data. There is no need to configure dedicated random access resources for downlink SDT data, which can save the overhead of random access resources. On the other hand, for 4-step random access, the first CU can determine whether the terminal has uplink SDT data based on the random access resources used by the terminal to initiate the random access process. If there is no uplink SDT data, the first CU can allocate a smaller grant to the terminal to transmit message 3, thereby avoiding resource waste. For 2-step random access, since there is no uplink SDT data, the terminal can select a smaller grant (i.e., the first random access resource) to transmit message A, which can also avoid resource waste. In addition, by introducing the seventh indication information in the random access process, it can help the second CU determine to keep the terminal in the RRC inactive state, so that downlink data can be transmitted in the RRC inactive state.

Optionally, if the terminal determines that the first condition or the second condition is not met based on the first indication information, the second random access process may be initiated using the second random access resource, and uplink SDT data and third indication information may be sent to the first DU during the second random access process. Then, the first DU may send the uplink SDT data and indication information indicating the content indicated by the third indication information to the first CU, and the first CU may send the uplink SDT data and indication information indicating the content indicated by the third indication information to the second CU. After the second CU receives the uplink SDT data and the indication information indicating the content indicated by the third indication information, it may determine to keep the terminal in an RRC inactive state. The operations thereafter may refer to the steps after S608, which will not be described in detail here.

FIG9 is a schematic flow chart of another data transmission method provided by the present application. The method 700 mainly describes the behavior of the terminal side from the perspective of the terminal, but it should be understood that although the behavior of the network side is not shown in FIG9, the behavior of the network side can be unambiguously derived from the description of the method 700. In addition, the terms or words in the method 700 that are the same as any of the previous methods, as well as the implementation methods of the corresponding contents, can all refer to the descriptions in the previous methods. The method 700 is described below.

S701: A terminal receives first indication information and a first threshold.

S702: The terminal determines whether there is an uplink SDT configuration.

If the terminal determines that there is an uplink SDT configuration, S703 is executed; otherwise, S705 is executed.

S703, the terminal determines whether there is uplink SDT data.

If the terminal determines that there is uplink SDT data, S704 is executed; otherwise, S705 is executed.

S704: The terminal initiates a second random access process using a second random access resource.

Similar to any of the above methods, the terminal may send uplink data and the third indication information in the second random access process. The network side may send downlink data in the SDT process including the second random access process.

S705: The terminal determines whether the current signal quality is greater than or equal to a first threshold.

If the terminal determines that the current signal quality is greater than or equal to the first threshold, S706 is executed; otherwise, S707 is executed.

S706: The terminal initiates a first random access process using the first random access resource, and sends second indication information and third indication information to the network side during the first random access process.

After receiving the second indication information, the network side determines to maintain the RRC inactive state of the terminal according to the second indication information, and sends downlink data during the SDT process.

S707: The terminal initiates a first random access process using the first random access resource, and sends third indication information to the network side during the first random access process.

If the network side does not receive the second indication information in the first random access process, it determines to restore the RRC connection. After the RRC connection is restored, downlink data can be sent to the terminal.

According to the data transmission method provided by the present application, the terminal can determine the random access resources used to initiate the random access process and the information that needs to be carried in the random access process according to whether there is an uplink SDT configuration, whether there is uplink SDT data, and whether the current signal quality of the terminal is greater than or equal to the first threshold. In this way, on the one hand, the random access resources of the random access process without uplink SDT data can be shared in the absence of uplink SDT data or uplink SDT configuration to initiate a random access process that can transmit downlink SDT data, thereby saving the overhead of random access resources. On the other hand, by determining whether to carry the second indication information in the first random access process, it can help the network side determine whether to switch to the RRC connection state or whether to remain in the RRC inactive state, so as to better meet the needs of the business.

It should be understood that method 700 is applicable to any network architecture, such as the network device currently accessed by the terminal is the last service access network device, the network device currently accessed by the terminal is not the last service access network device, the network device currently accessed by the terminal and/or the last service access network device of the focus is a CU-DU architecture. At the same time, it should be understood that when method 700 is applied to any of these architectures, the corresponding information interaction can refer to methods 300 to 600, and the process of applying method 700 under different network architectures will not be repeated in this application.

The above describes the method embodiment provided by the present application, and the following describes the device embodiment provided by the present application. It should be understood that the description of the device embodiment corresponds to the description of the method embodiment, so the content not described in detail can be referred to the method embodiment above, and for the sake of brevity, it will not be repeated here.

Figure 10 is a schematic block diagram of a communication device provided in an embodiment of the present application. As shown in Figure 10, the communication device 2000 may include a communication unit 2100. Optionally, it may also include a processing unit 2200. The communication unit 2100 may implement a corresponding communication function, and the communication may be an internal communication of the communication device 2000 or a communication between the communication device 2000 and other devices; the processing unit 2200 may implement a corresponding processing function. The communication unit 2100 may also be referred to as a communication interface or a transceiver unit. Optionally, the communication device 2000 may also include a storage unit, which may be used to store instructions and/or data, and the processing unit 2200 may read the instructions and/or data in the storage unit so that the device implements the aforementioned method embodiment.

In one possible design, the communication device 2000 may be the terminal in the above method 300, or may be a module or chip applied to the terminal. The communication device 2000 may be used to execute the steps or processes executed by the terminal in the above method 300. The communication device 2000 is currently in an RRC inactive state.

Specifically, the communication unit 2100 is used to receive a first paging message from a first network device, the first paging message including first indication information, and the first indication information is used to instruct the communication device 2000 to initiate a small data transmission SDT process; the processing unit 2200 is used to, according to the first indication information, when it is determined that the first condition or the second condition is met, control the communication unit 2100 to use the first random access resource to initiate a first random access process, and send second indication information and third indication information to the first network device during the first random access process, the first condition including that the communication device 2000 has no uplink SDT data, the second condition including that there is no uplink SDT configuration, the first random access resource does not belong to the first resource set, the resources in the first resource set are random access resources for the random access process of sending uplink SDT data, the second indication information indicates that the communication device 2000 has initiated the SDT process, and the third indication information is used to request to restore the RRC connection; the communication unit 2100 is also used to receive downlink data from the first network device during the SDT process, and the SDT process includes the first random access process.

Optionally, the processing unit 2200 is further configured to, according to the first indication information, if the first condition is not met: The control communication unit 2100 uses the second random access resource to initiate a second random access process, and in the second random access process, sends uplink SDT data and the third indication information to the first network device, wherein the second random access resource belongs to the first resource set; the communication unit 2100 is also used to receive the downlink data from the first network device during the SDT process, and the SDT process includes the second random access process.

Optionally, the first condition or the second condition also includes that the current signal quality of the communication device 2000 is greater than or equal to a first threshold.

Optionally, the communication unit 2100 is further used to receive the first threshold from the first network device.

Optionally, the signal quality includes reference signal received power RSRP and/or reference signal received quality RSRQ.

Optionally, the first random access process is a 4-step random access process, and message 3 in the 4-step random access process includes the second indication information and the third indication information; or, the first random access process is a 2-step random access process, and message A in the 2-step random access process includes the second indication information and the third indication information.

Optionally, the message 3 or the message A includes an RRC recovery request, and the RRC recovery request includes the second indication information and the third indication information; or, the message 3 or the message A includes the second indication information and an RRC recovery request, the RRC recovery request is the third indication information, and the second indication information is one or more of the following: SDT auxiliary information, indication information indicating the initiation of the SDT process, current signal quality information of the communication device 2000, a first media access control control unit MAC CE, or a second MAC CE, the first MAC CE includes a first logical channel identifier indicating the initiation of the SDT process, and the second MAC CE is a configuration authorization confirmation MAC CE.

Optionally, the communication unit 2100 is further used to receive an RRC release message from the first network device, where the RRC release message is used to instruct the communication apparatus 2000 to remain in the RRC inactive state and terminate the SDT process.

Optionally, the first network device is a first distributed unit DU.

In one possible design, the communication device 2000 may be the first network device in the above method 300 or method 400, or may be a module or chip applied to the first network device. The communication device 2000 may be used to execute the steps or processes executed by the first network device in the above method 300 or method 400.

Specifically, the communication unit 2100 is used to: send a first paging message to a terminal, the terminal is currently in a radio resource control (RRC) inactive state, the first paging message includes first indication information, the first indication information is used to indicate that the terminal initiates a small data transmission (SDT) process; receive second indication information and third indication information from the terminal during a first random access process initiated using a first random access resource, or receive uplink SDT data and the third indication information from the terminal during a second random access process initiated using a second random access resource, wherein the first random access resource does not belong to a first resource set, the resources in the first resource set are random access resources for a random access process for sending uplink SDT data, the second random access resource belongs to the first resource set, the second indication information indicates that the terminal has initiated the SDT process, and the third indication information is used to request restoration of the RRC connection; during the SDT process, send downlink data to the terminal, and the SDT process includes the first random access process or the second random access process.

Optionally, the communication unit 2100 is further used to send a first threshold to the terminal, where the first threshold is used by the terminal to determine whether to initiate the first random access procedure or initiate the second random access procedure.

Optionally, the first random access process is a 4-step random access process, and message 3 in the 4-step random access process includes the second indication information and the third indication information; or, the first random access process is a 2-step random access process, and message A in the 2-step random access process includes the second indication information and the third indication information; or, the second random access process is a 4-step random access process, and message 3 in the 4-step random access process includes the uplink SDT data and the third indication information; or, the second random access process is a 2-step random access process, and message A in the 2-step random access process includes the uplink data and the third indication information.

Optionally, for the first random access process, the message 3 or the message A includes an RRC recovery request, and the RRC recovery request includes the second indication information and the third indication information; or, for the first random access process, the message 3 or the message A includes the second indication information and an RRC recovery request, the RRC recovery request is the third indication information, and the second indication information is one or more of the following: SDT auxiliary information, indication information indicating the initiation of the SDT process, the current signal quality information of the terminal, a first media access control control unit MAC CE, or a second MAC CE, the first MAC CE includes a first logical channel identifier indicating the initiation of the SDT process, and the second MAC CE is a configuration authorization confirmation MAC CE.

Optionally, the communication device 2000 is the first distributed unit DU in method 500 or method 600.

Optionally, the communication unit 2100 is also used to receive a second paging message from the first CU, the second paging message including fourth indication information, the fourth indication information indicating that the terminal initiates the SDT process; send fifth indication information to the first CU, the fifth indication information indicating that the terminal has initiated the SDT process, or send the uplink SDT data to the first CU; and receive the downlink data from the first CU.

Optionally, the communication unit 2100 is also used to receive a second paging message from a second network device, the second paging message including an identifier of the terminal and fourth indication information, the fourth indication information indicating that the terminal initiates the SDT process; send a first request message to the second network device, the first request message is used to request the context of the terminal, and the first request message includes fifth indication information, the fifth indication information indicating that the terminal has initiated the SDT process; receive part or all of the context and the downlink data of the terminal from the second network device.

In a possible design, the communication device 2000 may be the second network device in the above method 400, or may be a module or chip applied to the second network device. The communication device 2000 may be used to execute the steps or processes executed by the second network device in the above method 400.

Specifically, the communication unit 2100 is used to send a second paging message to the first network device, the second paging message including the terminal identifier and fourth indication information, the terminal is currently in an inactive state of the radio resource control RRC, and the fourth indication information is used to indicate that the terminal initiates a small data transmission SDT process; receive a first request message from the first network device, the first request message is used to request the context of the terminal, and the first request message includes fifth indication information, the second indication information indicates that the terminal has initiated the SDT process; and according to the fifth indication information, send part or all of the context of the terminal and the downlink data of the terminal to the first network device.

In one possible design, the communication device 2000 may be used to implement the various steps or processes of method 700. For example, the communication device may be a terminal that executes method 700 or a module or chip applied to a terminal.

It should be understood that the communication device 2000 can also implement various steps or processes on the network side related to the method 700.

In one possible design, the communication device 2000 may be the first DU in the above method 500 or method 600, or may be a module or chip applied to the first DU. The communication device 2000 may be used to execute the steps or processes executed by the first DU in the above method 500 or method 600, and the details may refer to the above method 500 or method 600, which will not be described in detail here.

In one possible design, the communication device 2000 may be the first CU in the above method 500 or method 600, or may be a module or chip applied to the first CU. The communication device 2000 may be used to execute the steps or processes executed by the first CU in the above method 500 or method 600, and specific reference may be made to the above method 500 or method 600, which will not be described in detail here.

In one possible design, the communication device 2000 may be the second CU in the above method 600, or may be a module or chip applied to the second CU. The communication device 2000 may be used to execute the steps or processes executed by the second CU in the above method 600, and the details may refer to the above method 600, which will not be described in detail here.

It should be understood that the "unit" in the communication device 2000 can be implemented by hardware, can be implemented by software, and can also be implemented by hardware to execute the corresponding software implementation. For example, the "unit" can refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (such as a shared processor, a dedicated processor or a group processor, etc.) and a memory for executing one or more software or firmware programs, a combined logic circuit and/or other suitable components that support the described functions. For another example, the communication unit 2100 can be replaced by a transceiver transceiver circuit (for example, it can include a receiving circuit and a transmitting circuit), and the processing unit 2200 can be replaced by a processor or a processing circuit.

FIG11 shows a schematic block diagram of another communication device 3000 provided in an embodiment of the present application. The communication device 3000 may be a terminal, a first network device, a second network device, a first DU, a first CU or a second CU, or may be a chip, a chip system, or a processor that supports the terminal, the first network device, the second network device, the first DU, the first CU or the second CU to implement the above method. The device may be used to implement the method described in the above method embodiment, and the details may refer to the description in the above method embodiment.

The communication device 3000 may include one or more processors 3100, which may also be referred to as a processing unit, and may implement certain control functions. The processor 3100 may be a general-purpose processor or a dedicated processor, etc. For example, it may be a baseband processor or a central processing unit. The baseband processor may be used to process the communication protocol and the communication data, and the central processing unit may be used to control the communication device (e.g., a base station, a baseband chip, a user chip, a DU or a CU, etc.), execute a software program, and process the data of the software program.

In an optional design, the processor 3100 may also store instructions and/or data, which can be executed by the processor 3100 so that the communication device 3000 executes the method described in the above method embodiment.

In another optional design, the communication device 3000 may include a communication interface 3200 for implementing the receiving and sending functions. For example, the communication interface 3200 may be a transceiver circuit, an interface, an interface circuit, or a transceiver. The transceiver circuit, interface, interface circuit, or transceiver for implementing the receiving and sending functions may be separate or integrated. The above-mentioned transceiver circuit, interface, interface circuit, or transceiver may be used for reading and writing code/data, or the above-mentioned transceiver circuit, interface, interface circuit, or transceiver may be used for transmission or transfer of signals.

Optionally, the communication device 3000 may include one or more memories 3300, on which instructions may be stored, and the instructions may be executed on the processor 3100, so that the communication device 3000 performs the method described in the above method embodiment. Optionally, data may also be stored in the memory 3300. Optionally, instructions and/or data may also be stored in the processor 3100. The processor 3100 and the memory 3300 may be provided separately or integrated together.

FIG12 is a schematic diagram of the structure of a terminal 4000 provided by the present application. The above-mentioned communication device 2000 or communication device 3000 can be configured in the terminal 4000. Alternatively, the communication device 2000 or communication device 3000 itself can be the terminal 4000. In other words, the terminal 4000 can perform the actions performed by the terminal in the above-mentioned method embodiment. Optionally, for ease of explanation, FIG12 only shows the main components of the terminal. As shown in FIG12, the terminal 4000 includes a processor, a memory, a control circuit, an antenna, and an input and output device.

The processor is mainly used to process the communication protocol and communication data, as well as to control the entire terminal, execute the software program, and process the data of the software program, for example, to support the terminal to perform the actions described in the above method embodiment. The memory is mainly used to store software programs and data. The control circuit is mainly used for the conversion of baseband signals and radio frequency signals and the processing of radio frequency signals. The control circuit and the antenna can also be called a transceiver, which is mainly used to send and receive radio frequency signals in the form of electromagnetic waves. Input and output devices, such as touch screens, display screens, keyboards, etc. are mainly used to receive data input by users and output data to users.

When the terminal is turned on, the processor can read the software program in the storage unit, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be sent wirelessly, the processor performs baseband processing on the data to be sent, and outputs the baseband signal to the RF circuit. The RF circuit performs RF processing on the baseband signal and then sends the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the terminal, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data and processes the data.

Those skilled in the art will appreciate that, for ease of explanation, FIG. 12 shows only one memory and processor. In an actual terminal, there may be multiple processors and memories. The memory may also be referred to as a storage medium or a storage device, etc., which is not limited in the embodiments of the present application.

For example, the processor may include a baseband processor and a central processing unit. The baseband processor is mainly used to process the communication protocol and communication data, and the central processing unit is mainly used to control the entire terminal, execute the software program, and process the data of the software program. The processor in Figure 12 integrates the functions of the baseband processor and the central processing unit. Those skilled in the art will understand that the baseband processor and the central processing unit may also be independent processors, interconnected by technologies such as buses. Those skilled in the art will understand that the terminal may include multiple baseband processors to adapt to different network formats, and the terminal may include multiple central processing units to enhance its processing capabilities. The various components of the terminal may be connected through various buses. The baseband processor may also be described as a baseband processing circuit or a baseband processing chip. The central processing unit may also be described as a central processing circuit or a central processing chip. The function of processing the communication protocol and communication data may be built into the processor, or may be stored in the storage unit in the form of a software program, and the processor executes the software program to implement the baseband processing function.

Exemplarily, in the embodiment of the present application, the antenna and the control circuit having the transceiver function may be regarded as the transceiver unit 4100 of the terminal 4000, and the processor having the processing function may be regarded as the processing unit 4200 of the terminal 4000. As shown in FIG. 12 , the terminal 4000 includes a transceiver unit 4100 and a processing unit 4200. The transceiver unit may also be referred to as a transceiver, a transceiver, a transceiver device, etc. Optionally, the device for realizing the receiving function in the transceiver unit 4100 may be regarded as a receiving unit, and the device for realizing the sending function in the transceiver unit 4100 may be regarded as a sending unit, that is, the transceiver unit 4100 includes a receiving unit and a sending unit. Exemplarily, the receiving unit may also be referred to as a receiver, a receiver, a receiving circuit, etc., and the sending unit may be referred to as a transmitter, a transmitter, or a sending circuit, etc.

FIG. 13 is a schematic diagram of the structure of an access network device 5000 provided in an embodiment of the present application. The above-mentioned communication device 2000 or communication device 3000 can be configured in the access network device 5000. Alternatively, the communication device 2000 or communication device 3000 itself can be the access network device 5000. Alternatively, the access network device 5000 can execute the first network device in the above-mentioned method embodiment. The action is performed by the first network device, the second network device, the first CU, the first DU, or the second CU.

As shown in FIG. 13 , the access network device 5000 may include one or more DU 5010 and one or more CU 5020. CU 5020 may communicate with NG core (Next Generation Core Network, NC). The DU 5010 may include at least one antenna 5011, at least one radio frequency unit 5012, at least one processor 5013 and at least one memory 5014. The DU 5010 part is mainly used for receiving and transmitting radio frequency signals, converting radio frequency signals to baseband signals, and part of baseband processing. CU 5020 may include at least one processor 5022 and at least one memory 5021. CU 5020 and DU 5010 may communicate through an interface, wherein the control plane (CP) interface may be Fs-C, such as F1-C, and the user plane (UP) interface may be Fs-U, such as F1-U.

The CU 5020 part is mainly used for baseband processing, controlling the access network device 5000, etc. The DU 5010 and CU 5020 can be physically set together or physically separated, that is, a distributed base station. The CU 5020 is the control center of the access network device 5000, which can also be called a processing unit, and is mainly used to complete the baseband processing function. For example, the CU 5020 can be used to control the access network device 5000 to execute the operation process of the network device in the above method embodiment.

Specifically, the baseband processing on the CU and DU can be divided according to the protocol layer of the wireless network, for example, the functions of the PDCP layer and above protocol layers are set in the CU, and the functions of the protocol layers below the PDCP, such as the RLC layer and the MAC layer, are set in the DU. For another example, the CU implements the functions of the RRC layer and the PDCP layer, and the DU implements the functions of the RLC layer, the MAC layer, and the PHY layer.

In addition, optionally, the access network device 5000 may include one or more radio frequency units (RUs), one or more DUs, and one or more CUs. The DU may include at least one processor 5013 and at least one memory 5014, the RU may include at least one antenna 5011 and at least one radio frequency unit 5012, and the CU may include at least one processor 5022 and at least one memory 5021.

In one example, the CU 5020 may be composed of one or more boards, and the multiple boards may jointly support a wireless access network with a single access standard (such as a 5G network), or may respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 5021 and the processor 5022 may serve one or more boards. In other words, a memory and a processor may be separately set on each board. It is also possible that multiple boards share the same memory and processor. In addition, necessary circuits may be set on each board. The DU 5010 may be composed of one or more boards, and the multiple boards may jointly support a wireless access network with a single access indication (such as a 5G network), or may respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 5014 and the processor 5013 may serve one or more boards. In other words, a memory and a processor may be separately set on each board. It is also possible that multiple boards share the same memory and processor. In addition, necessary circuits may be set on each board.

It should be understood that the access network device 5000 shown in Figure 13 can implement the various processes of the actions performed by the first network device, the second network device, the first CU, the first DU, or the second CU in the foregoing method embodiments. For example, the CU and one of the DUs in the access network device 5000 can respectively implement the operations performed by the first CU and the first DU in method 500 or method 600, or the CU in the access network device 5000 can implement the operations performed by the second CU in method 600. The operations and/or functions of each module in the access network device 5000 are respectively to implement the corresponding processes in the above method embodiments. For details, please refer to the description in the above method embodiments. To avoid repetition, the detailed description is appropriately omitted here.

It should be understood that the access network device 5000 shown in FIG. 13 is only a possible architecture of the access network device and should not constitute any limitation to the present application. The method provided in the present application can be applied to access network devices of other architectures. For example, access network devices including CU, DU and AAU, etc. The present application does not limit the specific architecture of the access network device.

FIG14 is a schematic diagram of the structure of an access network device 6000 provided in an embodiment of the present application. The above-mentioned communication device 2000 or communication device 3000 can be configured in the access network device 6000. Alternatively, the communication device 2000 or communication device 3000 itself can be the access network device 6000. Alternatively, the access network device 6000 can perform the operations performed by the first network device or the second network device in the above-mentioned method embodiment.

The access network device 6000 may include one or more radio frequency units, such as a remote radio unit (RRU) 6100 and one or more baseband units (BBU) (also referred to as digital units, DU) 6200. The RRU 6100 may be referred to as a transceiver unit, a transceiver, a transceiver circuit, or a transceiver, etc., and may include at least one antenna 6110 and a radio frequency unit 6120. The RRU 6100 part is mainly used for the transmission and reception of radio frequency signals and the conversion of radio frequency signals and baseband signals. The BBU 6200 part is mainly used for baseband processing, controlling the access network device 6000, etc. The RRU 6100 and the BBU 6200 may be physically arranged together or physically separated, i.e., a distributed base station.

The BBU 6200 is the control center of the access network device 6000, which can also be called a processing unit, and is mainly used to complete baseband processing functions, such as channel coding, multiplexing, modulation, spread spectrum, etc. For example, the BBU (processing unit) 6200 can be used to control the access network device 6000 to execute the operation flow of the transmitter or the receiver in the above method embodiment.

In one example, the BBU 6200 may be composed of one or more boards, and the multiple boards may jointly support a wireless access network of a single access standard (such as an LTE system or a 5G system), or may respectively support wireless access networks of different access standards. The BBU 6200 also includes a memory 6210 and a processor 6220. The memory 6210 is used to store necessary instructions and data. The processor 6220 is used to control the access network device 6000 to perform necessary actions, for example, to control the access network device 6000 to execute the operation process of the first access network device or the second access network device in the above method embodiment. The memory 6210 and the processor 6220 may serve one or more boards. That is, a memory and a processor may be separately set on each board. It is also possible that multiple boards share the same memory and processor. In addition, necessary circuits may be set on each board.

In a possible implementation, with the development of system-on-chip (SoC) technology, all or part of the functions of part 6200 and part 6100 can be implemented by SoC technology, for example, by a base station function chip, which integrates a processor, a memory, an antenna interface and other devices, and the program of the base station related functions is stored in the memory, and the processor executes the program to implement the related functions of the base station. Optionally, the base station function chip can also read the memory outside the chip to implement the related functions of the base station.

It should be understood that the structure of the access network device 6000 illustrated in FIG14 is only one possible form and should not constitute any limitation to the embodiments of the present application. The present application does not exclude the possibility of other forms of base station structures that may appear in the future.

It should be understood that in a possible design, each step in the method embodiment provided by the present application can be completed by an integrated logic circuit of hardware in a processor or an instruction in the form of software. The steps of the method disclosed in conjunction with the embodiment of the present application can be directly embodied as a hardware processor to be executed, or a combination of hardware and software modules in a processor to be executed. The software module can be located in a storage medium mature in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it is not described in detail here.

It should be noted that the processor in the embodiment of the present application can be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment can be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to perform, or the hardware and software modules in the decoding processor can be combined and performed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

It can be understood that the memory in the embodiments of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

The present application also provides a computer program product, which includes: computer program code, when the computer program code is run on a computer, the computer executes each step or process executed by the terminal, the first network device, the second network device, the first CU, the first DU or the second CU in any of the above method embodiments.

The present application also provides a computer-readable storage medium, which stores a program code. When the program code runs on a computer, the computer executes each step or process executed by the terminal, the first network device, the second network device, the first CU, the first DU or the second CU in any of the above method embodiments.

The present application also provides a communication system, which includes one or more of the following: a terminal or a first network device; or, a terminal, a first network device or a second network device; or, a terminal, a first DU or a first CU; or, a terminal, a first DU, a first CU or a second CU.

The above-mentioned device embodiments and method embodiments completely correspond to each other, and the corresponding steps are executed by the corresponding modules or units. For example, the communication unit or communication interface executes the receiving or sending steps in the method embodiment, and the other steps except sending and receiving can be executed by the processing unit or processor.

In the embodiments of the present application, each term and English abbreviation is provided for the convenience of description and shall not constitute any limitation to the present application. The present application does not exclude the possibility of defining other terms that can achieve the same or similar functions in existing or future protocols.

The terms "component", "module", "system", etc. used in this specification are used to represent computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program and/or a computer. By way of illustration, both applications running on a computing device and a computing device can be components. One or more components may reside in a process and/or an execution thread, and a component may be located on a computer and/or distributed between two or more computers. In addition, these components may be executed from various computer-readable storage media having various data structures stored thereon. Components may, for example, communicate through local and/or remote processes according to signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system and/or a network, such as the Internet interacting with other systems through signals).

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

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

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

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

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

In the above embodiments, the functions of each functional unit can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions (programs). When the computer program instructions (programs) are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a medium containing a or a data storage device such as a server or data center that integrates multiple available media. The available media may be magnetic media (e.g., floppy disks, hard disks, tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid state disks (SSDs)).

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

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

Claims

A data transmission method, characterized in that it is applied to a terminal, wherein the terminal is currently in a radio resource control (RRC) inactive state, and the method comprises:

Receiving a first paging message from a first network device, where the first paging message includes first indication information, where the first indication information is used to instruct the terminal to initiate a small data transmission SDT process;

According to the first indication information, when the first condition or the second condition is met, a first random access process is initiated using a first random access resource, and a first request message is sent to the first network device during the first random access process, the first condition includes that the terminal has no uplink SDT data, the second condition includes that there is no uplink SDT configuration, the first random access resource does not belong to a first resource set, the resources in the first resource set are random access resources for a random access process for sending uplink SDT data, the first request message is used to request to restore the RRC connection, and the first request message is used to indicate that the terminal has initiated the SDT process;

Downlink data is received from the first network device during the SDT process, and the SDT process includes the first random access process.
The method according to claim 1, characterized in that the method further comprises:

Initiate a second random access process using a second random access resource according to the first indication information if the first condition is not met, and send uplink SDT data and the third indication information to the first network device during the second random access process, wherein the second random access resource belongs to the first resource set;

The downlink data is received from the first network device during the SDT process, and the SDT process includes the second random access process.
The method according to claim 1 or 2, characterized in that the first condition or the second condition further comprises that the current signal quality of the terminal is greater than or equal to a first threshold;

And, the method further comprises:

The first threshold is received from the first network device.
The method as claimed in claim 3 is characterized in that the signal quality includes reference signal received power RSRP and/or reference signal received quality RSRQ.
The method according to any one of claims 1 to 4, characterized in that the first random access process is a 4-step random access process, and message 3 in the 4-step random access process includes the second indication information and the third indication information;

Alternatively, the first random access procedure is a two-step random access procedure, and the message A in the two-step random access procedure includes the second indication information and the third indication information.
The method according to claim 5, characterized in that the message 3 or the message A includes an RRC recovery request, and the RRC recovery request includes the second indication information and the third indication information; or

The message 3 or the message A includes the second indication information and an RRC recovery request, the RRC recovery request is the third indication information, the second indication information is one or more of the following: SDT auxiliary information, indication information indicating the initiation of the SDT process, the current signal quality information of the terminal, the first media access control control unit MAC CE, or the second MAC CE, the first MAC CE includes the first logical channel identifier indicating the initiation of the SDT process, and the second MAC CE is a configuration authorization confirmation MAC CE.
The method according to any one of claims 1 to 6, characterized in that the method further comprises:

An RRC release message is received from the first network device, where the RRC release message is used to instruct the terminal to remain in the RRC inactive state and terminate the SDT process.
The method according to any one of claims 1-7 is characterized in that the first network device is a first distributed unit DU.
A data transmission method, characterized in that it is applied to a first network device, the method comprising:

Sending a first paging message to a terminal, where the terminal is currently in a radio resource control (RRC) inactive state, the first paging message including first indication information, where the first indication information is used to instruct the terminal to initiate a small data transmission (SDT) process;

receiving a first request message from the terminal during a first random access process initiated using a first random access resource, or,

receiving uplink SDT data and the first request message from the terminal in a second random access process initiated by using a second random access resource,

The first random access resource does not belong to the first resource set, the resources in the first resource set are random access resources for a random access process of sending uplink SDT data, the second random access resource belongs to the first resource set, the first request message is used to request restoration of the RRC connection, and the first request message is used to indicate that the terminal has initiated the SDT process;

In the SDT process, downlink data is sent to the terminal, and the SDT process includes the first random access process or the second random access process.
The method according to claim 9, characterized in that before sending the first paging message to the terminal, the method further comprises:

A first threshold is sent to the terminal, where the first threshold is used by the terminal to determine whether to initiate the first random access procedure or to initiate the second random access procedure.
The method according to claim 9 or 10, characterized in that the first random access process is a 4-step random access process, and message 3 in the 4-step random access process includes the second indication information and the third indication information;

Alternatively, the first random access procedure is a two-step random access procedure, and message A in the two-step random access procedure includes the second indication information and the third indication information;

Alternatively, the second random access procedure is a 4-step random access procedure, and message 3 in the 4-step random access procedure includes the uplink SDT data and the third indication information;

Alternatively, the second random access procedure is a two-step random access procedure, and a message A in the two-step random access procedure includes the uplink SDT data and the third indication information.
The method according to claim 11, characterized in that, for the first random access procedure, the message 3 or the message A includes an RRC recovery request, and the RRC recovery request includes the second indication information and the third indication information; or

For the first random access process, the message 3 or the message A includes the second indication information and an RRC recovery request, the RRC recovery request is the third indication information, the second indication information is one or more of the following: SDT auxiliary information, indication information indicating the initiation of the SDT process, the current signal quality information of the terminal, the first media access control control unit MAC CE, or the second MAC CE, the first MAC CE includes a first logical channel identifier indicating the initiation of the SDT process, and the second MAC CE is a configuration authorization confirmation MAC CE.
The method according to any one of claims 9 to 12, wherein the first network device is a first distributed unit DU.
The method according to claim 13, characterized in that before sending the first paging message to the terminal, the method further comprises:

receiving a second paging message from the first CU, where the second paging message includes fourth indication information, where the fourth indication information instructs the terminal to initiate the SDT process;

Wherein, after receiving the second indication information and the third indication information from the terminal in the first random access process initiated by using the first random access resource, the method further includes:

Sending fifth indication information to the first CU, where the fifth indication information indicates that the terminal has initiated the SDT process;

Alternatively, after receiving the uplink SDT data and the third indication information from the terminal in the second random access process initiated by using the second random access resource, the method further includes:

Sending the uplink SDT data to the first CU;

Wherein, in the SDT process, before sending the downlink data to the terminal, the method further includes:

Receive the downlink data from the first CU.
The method according to any one of claims 9 to 12, characterized in that before sending the first paging message to the terminal, the method further comprises:

receiving a second paging message from a second network device, where the second paging message includes an identifier of the terminal and fourth indication information, where the fourth indication information indicates that the terminal initiates the SDT process;

And, in the SDT process, before sending the downlink data to the terminal, the method further includes:

Sending a first request message to the second network device, where the first request message is used to request the context of the terminal, and the first request message includes fifth indication information, where the fifth indication information indicates that the terminal has initiated the SDT process;

Receive part or all of the context of the terminal and the downlink data from the second network device.
A data transmission method, characterized in that it is applied to a second network device, the method comprising:

Sending a second paging message to the first network device, where the second paging message includes an identifier of the terminal and fourth indication information, where the terminal is currently in a radio resource control (RRC) inactive state, and the fourth indication information is used to instruct the terminal to initiate a small data transmission (SDT) process;

receiving a first request message from the first network device, where the first request message is used to request a context of the terminal, and the first request message includes fifth indication information, where the fifth indication information indicates that the terminal has initiated the SDT process;

According to the fifth indication information, part or all of the context of the terminal and the downlink data of the terminal are sent to the first network device.
A communication device, characterized by comprising a unit for executing each step of the method as described in any one of claims 1 to 8.
A communication device, characterized in that it comprises a unit for executing each step of the method as described in any one of claims 9 to 15.
A communication device, characterized by comprising a unit for executing each step of the method according to claim 16.
A communication device, characterized in that it includes a processor, the processor is coupled to a memory, the memory is used to store programs or instructions, and when the program or instructions are executed by the processor, the device executes the method as described in any one of claims 1-8, any one of 9-15 or 16.
A computer-readable storage medium having a computer program or instruction stored thereon, wherein when the computer program or instruction is executed, the computer executes the method as claimed in any one of claims 1 to 8, any one of claims 9 to 15, or 16.
A computer program product, characterized in that it comprises computer program instructions, wherein the computer program instructions enable the computer to execute the method as claimed in any one of claims 1 to 8, any one of claims 9 to 15, or 16.
A chip, characterized in that it includes: a processor, used to call and run a computer program from a memory, so that a communication device equipped with the chip executes the method as described in any one of claims 1-8, any one of 9-15 or 16.