CN116962306A - Data transmission method and communication device - Google Patents

Abstract

The present application provides a data transmission method and communication device. The method includes: performing small data packet transmission between a terminal device and a network device; the second network device sends first downlink data to the terminal device through the first network device; The terminal device feeds back to the first network device the successful or unsuccessful reception of the first downlink data, and the first network device feeds back to the second network device the terminal device successfully or unsuccessfully received the first downlink data, so that the second network device can receive the first downlink data successfully or unsuccessfully according to the second network device. A network device feedback message determines the sending window for communication between the second network device and the terminal device. The method and device can improve the packet loss rate during small data packet transmission.

Description

Data transmission method and communication device

Technical field

The embodiments of the present application relate to the field of wireless communications, and more specifically, to a data transmission method and a communication device.

Background technique

The terminal equipment (user equipment, UE) communicates with the network side through a new base station node (generation nodeb, gNB). The gNB also configures a RAN based notification area (RAN based notification area, RNA) for the UE to move down. When the UE moves within the RNA, it may leave the coverage area of the previous gNB. At this time, if the UE needs to transmit a small amount of data with the network side, it can establish a connection with other gNBs in the RNA through random access, thereby communicating with the network. side for small packet transmission. During the transmission process of this small data packet, the problem of packet loss is likely to occur. Therefore, how to reduce the packet loss rate is called an urgent problem to be solved.

Contents of the invention

This application provides a data transmission method and communication device, which can reduce the packet loss rate during the transmission of small data packets.

In the first aspect, a data transmission method is provided. The method can be executed by a first network device, or can also be executed by a component (such as a chip or circuit) of the first network device. This application does not limit this. . For convenience of description, the following description takes execution by the first network device as an example.

The method may include: a first network device receiving first downlink data from a second network device, where the first downlink data is small data; the first network device sending the first downlink data to a terminal device; A network device receives a first feedback message from the terminal device. The first feedback message is used to indicate successful or unsuccessful reception of the first downlink data. The feedback message corresponds to the first protocol layer; the first network device is based on The first feedback message sends a second feedback message to the second network device. The first feedback message is used to indicate that the first downlink data is successfully received. The second feedback message is used to indicate that the terminal device successfully receives the data. The first downlink data and the second feedback message correspond to the second protocol layer.

In the above solution, during the small data packet transmission process, the first network device sends a second feedback message to the second network device. The second feedback message indicates whether the terminal device has successfully or unsuccessfully received the first downlink data, so that the second network device The device obtains whether the terminal device successfully receives the first downlink data, so that the sending window of the downlink data can be adjusted according to the data successfully received by the terminal device, thereby reducing the risk caused by the second network device being unable to know whether the first downlink data is successfully received by the terminal device. Adjust the packet loss caused by adjusting the sending window to reduce the packet loss rate.

In connection with the first aspect, in some implementations of the first aspect, the first feedback message includes at least one of the following: a sequence number of the first downlink data in the first protocol layer, a sequence number carrying the first downlink data The identifier of the radio bearer and the identifier of the logical channel carrying the first downlink data. The second feedback message includes at least one of the following: the sequence number of the first downlink data in the second protocol layer, the first downlink data The serial number of the downlink data in the first protocol layer, the identifier of the radio bearer carrying the first downlink data, and the identifier of the logical channel carrying the first downlink data.

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the first network device starting a timer according to the first feedback message.

With reference to the first aspect, in some implementations of the first aspect, the first network device sends a second feedback message to the second network device according to the first feedback message, including: when the timer times out, the The first network device sends a second feedback message to the second network device according to the first feedback message.

It should be understood that within the timing duration of the timer, the terminal device may feedback to the first network device whether multiple downlink data are successfully received. In the above solution, the first network device sets a timer and feedbacks to the second network device whether the terminal device successfully receives downlink data when the timer expires. Indicating the content in the feedback message can save signaling overhead.

With reference to the first aspect, in some implementations of the first aspect, the first network device sends a second feedback message to the second network device according to the first feedback message, including: the first network device sends a second feedback message to the second network device according to the first feedback message. The feedback message confirms that the terminal device successfully receives M pieces of data of the first protocol layer, M is a positive integer; when among the M pieces of data, the number of data with consecutive sequence numbers of the second protocol layer is greater than or equal to N, the A network device sends a second feedback message to the second network device. The second feedback message is used to indicate that the terminal device successfully receives N pieces of data of the second protocol layer, and the N pieces of data include the first downlink data, The N is a positive integer.

The above solution can save signaling overhead compared to indicating the content in the feedback message to the second network device every time it receives a feedback message from the terminal device. In addition, the sequence numbers of the N pieces of data fed back by the first network device to the second network device are consecutive, which can facilitate the second network device to directly push the sending window forward by N sequence numbers based on the second feedback message, and can also save money. The power consumption of the second network device to cache data.

With reference to the first aspect, in some implementations of the first aspect, the first protocol layer is a radio link control layer, and the second protocol layer is a packet data convergence layer.

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the first network device sending a first request message to the second network device, the first request message being used to request to obtain the terminal device In the context of the first request message, the first request message includes instruction information for indicating small data packet transmission; the first network device receives a first response message from the second network device, the first response message includes instruction information for indicating not to execute the anchor. Click relocation instructions.

It should be understood that the first network device requests the context of the terminal device from the second network device, indicating that the terminal device is no longer within the coverage of the second network device, and the second network device does not perform anchor point redirection, indicating that the second network device is still is the anchor point gNB. The above solution, in a scenario where anchor point relocation is not performed, allows the anchor point gNB to learn the status of the first protocol layer of the terminal device through the interaction between network devices based on the second protocol layer, so that the anchor point gNB can learn the status of the first protocol layer of the terminal device according to the terminal device's status. The status of the first protocol layer adjusts the sending window to reduce the packet loss rate.

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the first network device sending first indication information to the terminal device, the first indication information being used to indicate that the first network device supports Avoid data loss during the transmission of small data packets; the first network device receives fourth downlink data from the second network device, the fourth downlink data is data that the terminal device has not successfully received, and the fourth downlink data is small data packets. data; the first network device sends the fourth downlink data to the terminal device.

In the above solution, the first network device supports a mechanism to avoid data loss during the transmission of small data packets. It receives data that the terminal device has not successfully received from the second network device and retransmits the data to the terminal device, which can reduce the packet loss rate.

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the first network device sending a second request message to the second network device, the second request message being used to request to obtain the terminal device context, the second request message includes instruction information for indicating small data packet transmission; the first network device receives a second response message from the second network device, the second response message includes instruction information for indicating execution anchor point Relocation instructions.

It should be understood that the first network device requests the context of the terminal device from the second network device, indicating that the terminal device is no longer within the coverage of the second network device, and the second network device performs anchor point relocation, indicating that the anchor point gNB is the first network equipment. The above solution uses the anchor point gNB to forward the fourth downlink data to the terminal device through the anchor point gNB before relocating the anchor point, which can reduce the packet loss caused by the terminal device not being within the coverage of the second network device and reduce the packet loss rate. .

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the first network device sending a third request message to the second network device, the third request message being used to request to obtain the terminal device In the context, the third request message includes indication information for indicating small data packet transmission; the first network device receives a third response message from the second network device, the third response message includes indication information for indicating not to execute the anchor Click relocation instructions.

It should be understood that the first network device requests the context of the terminal device from the second network device, indicating that the terminal device is no longer within the coverage of the second network device, and the second network device does not perform anchor point relocation, indicating that the anchor point gNB is still the third network device. 2. Network equipment. In the above solution, the anchor gNB continues to forward the fourth downlink data to the terminal device through the first network device, which can reduce packet loss caused by the terminal device not being within the coverage of the second network device and reduce the packet loss rate.

With reference to the first aspect, in some implementations of the first aspect, the method further includes: the first network device sends a radio resource control release message to the terminal device, the radio resource control release message includes Y, where Y is small data The number of cell reselections during packet transmission, Y is a positive integer.

The second aspect provides a data transmission method, which can be executed by a second network device, or can also be executed by a component (such as a chip or circuit) of the second network device, which is not limited in this application. For convenience of description, the following description takes execution by the second network device as an example.

The method may include: the second network device sends first downlink data to the first network device, the first downlink data is small data, and the first network device is configured to send the first downlink data to the terminal device; The second network device receives a second feedback message from the first network device. The second feedback message is used to indicate whether the terminal device has successfully received or failed to receive the first downlink data. The second feedback message is consistent with the second protocol. layer correspondence; the second network device determines a second sending window based on the first sending window and the second feedback message. The first sending window contains the sequence number of the first downlink data. When the second feedback message indicates successful reception In the case of the first downlink data, the second sending window includes the sequence number of the downlink data that has not been sent to the terminal device.

In the above solution, the second network device sends the first downlink data to the terminal device through the first network device, determines whether the terminal device successfully receives the first downlink data according to the second feedback message sent by the first network device, and determines whether the terminal device successfully receives the first downlink data according to the second feedback message. Message adjustment sending window. If the second feedback message indicates that the terminal device successfully receives the first downlink data, the second network device pushes the sending window forward.

Combined with the second aspect, in some implementations of the second aspect, the second feedback message includes at least one of the following: the sequence number of the first downlink data in the second protocol layer, the sequence number of the first downlink data in the second protocol layer, The superframe number of the second protocol layer, the identifier of the radio bearer carrying the first downlink data, and the identifier of the logical channel carrying the first downlink data.

In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: the second network device determining, based on the second feedback message, that data corresponding to the first L sequence numbers of the first sending window have been sent by the second network device. If the terminal device receives successfully, the starting sequence number of the second sending window is equal to the sequence number corresponding to the L+1th data of the first sending window, and L is a positive integer.

In conjunction with the second aspect, in some implementations of the second aspect, the second feedback message is used to indicate that the terminal device successfully receives N pieces of data with consecutive sequence numbers of the second protocol layer, and the N pieces of data include the For a row of data, N is a positive integer, L=N.

In the above scheme, the sequence numbers of the N pieces of data fed back by the first network device to the second network device are consecutive, which can facilitate the second network device to directly push the sending window forward by N sequence numbers based on the second feedback message, or it can also Save power consumption of the second network device for caching data.

In conjunction with the second aspect, in some implementations of the second aspect, the second protocol layer is a packet data convergence layer.

With reference to the second aspect, in some implementations of the second aspect, the method further includes: the second network device receiving a first request message from the first network device, the first request message being used to request acquisition of the terminal In the context of the device, the first request message includes indication information for indicating small data packet transmission; the second network device sends a first response message to the first network device, the first response message includes indication information for indicating not to execute the anchor. Click relocation instructions.

It should be understood that the first network device requests the context of the terminal device from the second network device, indicating that the terminal device is no longer within the coverage of the second network device, and the second network device does not perform anchor point redirection, indicating that the second network device is still is the anchor point gNB. The above solution, in a scenario where anchor point relocation is not performed, allows the anchor point gNB to learn the status of the first protocol layer of the terminal device through the interaction between network devices based on the second protocol layer, so that the anchor point gNB can learn the status of the first protocol layer of the terminal device according to the terminal device's status. The status of the first protocol layer adjusts the sending window to reduce the packet loss rate.

In conjunction with the second aspect, some implementations of the second aspect include: the second network device sending second instruction information to the terminal device, the second instruction information being used to instruct to avoid data loss during small data packet transmission. ; The second network device sends fourth downlink data, and the fourth downlink data is small data; the second network device receives a first status report, and the first status report includes instructions for indicating that the terminal device has not successfully received the fourth Instruction information of downlink data; the second network device sends the fourth downlink data to the first network device.

In the above solution, the second network device supports a mechanism to avoid data loss during the transmission of small data packets, sends the data that the terminal device has not successfully received to the second network device, and retransmits the data to the terminal device through the second network device. Reduce packet loss rate.

With reference to the second aspect, in some implementations of the second aspect, the second network device sends fourth downlink data, including: the second network device sends the fourth downlink data to the terminal device; the second network device Receiving the first status report includes: the second network device receives the first status report from the terminal device.

With reference to the second aspect, in some implementations of the second aspect, the method further includes: the second network device receiving a second request message from the first network device, the second request message being used to request to obtain the terminal In the context of the device, the second request message includes instruction information for indicating small data packet transmission; the second network device sends a second response message to the second network device, the second response message includes instruction information for indicating execution anchor point Relocation instructions.

It should be understood that the first network device requests the context of the terminal device from the second network device, indicating that the terminal device is no longer within the coverage of the second network device, and the second network device performs anchor point relocation, indicating that the anchor point gNB is the first network equipment. The above solution uses the anchor point gNB to forward the fourth downlink data to the terminal device through the anchor point gNB before relocating the anchor point, which can reduce the packet loss caused by the terminal device not being within the coverage of the second network device and reduce the packet loss rate. .

Combined with the second aspect, in some implementations of the second aspect, the second network device sends fourth downlink data, including: the second network device sends the fourth downlink data to a third network device; the second network device The device receiving the first status report includes: the second network device receiving the first status report from the third network device.

In conjunction with the second aspect, in some implementations of the second aspect, the method further includes: the second network device sending a fourth request message to the third network device, the fourth request message being used to request the fourth downlink data status report.

With reference to the second aspect, in some implementations of the second aspect, the method further includes: the second network device receiving a third request message from the first network device, the third request message being used to request to obtain the terminal In the context of the device, the third request message includes instruction information for indicating small data packet transmission; the second network device sends a third response message to the first network device, the third response message includes instruction information for indicating not to execute the anchor. Click relocation instructions.

It should be understood that the first network device requests the context of the terminal device from the second network device, indicating that the terminal device is no longer within the coverage of the second network device, and the second network device does not perform anchor point relocation, indicating that the anchor point gNB is still the third network device. 2. Network equipment. In the above solution, the anchor gNB continues to forward the fourth downlink data to the terminal device through the first network device, which can reduce packet loss caused by the terminal device not being within the coverage of the second network device and reduce the packet loss rate.

Combined with the second aspect, in some implementations of the second aspect, the method further includes: the first network device sends a radio resource control release message to the terminal device, the radio resource control release message includes Y, where Y is small data The number of cell reselections during packet transmission, Y is a positive integer.

In the third aspect, a data transmission method is provided, which method can be executed by a terminal device, or can also be executed by a component (such as a chip or circuit) of the terminal device, which is not limited in this application. For convenience of description, the following description takes execution by a terminal device as an example.

The method may include: the terminal device receives second indication information from the second network device, the second indication information is used to indicate to avoid data loss during the transmission of small data packets; the terminal device receives fourth downlink data, the fourth downlink data The data is small data; the terminal device sends indication information indicating that the fourth downlink data has not been successfully received; the terminal device receives first indication information from the first network device, the first indication information is used to indicate the first The network device supports avoiding data loss during small data packet transmission; the terminal device receives fourth downlink data from the first network device.

In the above solution, the terminal device determines that the second network device supports a mechanism to avoid data loss during the transmission of small data packets based on the second instruction information, and determines based on the first instruction information that the first network device supports a mechanism to avoid data loss during the transmission of small data packets. , the terminal device has received unsuccessfully received fourth downlink data from the second network device from the first network device, which can reduce the packet loss rate during the transmission of small data packets.

With reference to the third aspect, in some implementations of the third aspect, the terminal device receiving fourth downlink data includes: the terminal device receiving the fourth downlink data from the second network device; and the terminal device sending for The indication information indicating that the fourth downlink data is not successfully received includes: the terminal device sends a first status report to the second network device, and the first status report includes the indication information.

In conjunction with the third aspect, in some implementations of the third aspect, the terminal device receiving fourth downlink data includes: the terminal device receiving the fourth downlink data from the third network device; and the terminal device sending for The indication information indicating that the fourth downlink data has not been successfully received includes: the terminal device sends a second status report to the third network device, and the second status report includes the indication information.

Combined with the third aspect, in some implementations of the third aspect, the method further includes: the terminal device receives a radio resource control release message from the network device, the radio resource control release message includes Y, where Y is a small data packet The number of cell reselections during the transmission process, Y is a positive integer; the terminal device initiates the small data packet transmission process; the terminal device records the number of cell reselections; when the number of cell reselections recorded by the terminal device is ≥ Y , the terminal device switches to the radio resource control idle state, or the terminal device sends a recovery request message for non-small data packet transmission to the network device.

The fourth aspect provides a data transmission method, which can be executed by a third network device, or can also be executed by a component (such as a chip or circuit) of the third network device, which is not limited in this application. For convenience of description, the following description takes the execution by the third network device as an example.

The method may include: the third network device receives fourth downlink data from the second network device, and the fourth downlink data is small data; the third network device sends the fourth downlink data to the terminal device; the third network device Receive a second status report from the terminal device, the second status report including indication information indicating that the terminal device has not successfully received the fourth downlink data; the third network device reports to the second status report according to the second status report. The network device sends a first status report, where the first status report includes indication information indicating that the terminal device has not successfully received the fourth downlink data.

In conjunction with the fourth aspect, in some implementations of the fourth aspect, the method further includes: the third network device receiving a fourth request message from the second network device, the fourth request message being used to request the fourth Status reporting of downstream data.

Combined with the fourth aspect, in some implementations of the fourth aspect, the method further includes: the third network device releases the link with the terminal device and stops communicating with the terminal device.

In the fifth aspect, a data transmission method is provided. The method can be executed by the first network device, or can also be executed by a component (such as a chip or circuit) of the first network device. This application is not limited to this. For convenience of description, the following description takes execution by the first network device as an example.

The method may include: the first network device sending first indication information to the terminal device, the first indication information being used to instruct the first network device to support avoiding data loss during small data packet transmission; the first network device receiving from The fourth downlink data of the second network device, the fourth downlink data is unsuccessfully received by the terminal device, and the fourth downlink data is small data; the first network device sends the fourth downlink data to the terminal device.

In conjunction with the fifth aspect, in some implementations of the fifth aspect, the method further includes: the first network device sending a second request message to the second network device, the second request message being used to request acquisition of the terminal device context, the second request message includes instruction information for indicating small data packet transmission; the first network device receives a second response message from the second network device, the second response message includes instruction information for indicating execution anchor point Relocation instructions.

In conjunction with the fifth aspect, in some implementations of the fifth aspect, the method further includes: the first network device sending a third request message to the second network device, the third request message being used to request acquisition of the terminal device In the context, the third request message includes indication information for indicating small data packet transmission; the first network device receives a third response message from the second network device, the third response message includes indication information for indicating not to execute the anchor Click relocation instructions.

In conjunction with the fifth aspect, in some implementations of the fifth aspect, the method further includes: the first network device sending a radio resource control release message to the terminal device, the radio resource control release message including Y, where Y is small data The number of cell reselections during packet transmission, Y is a positive integer.

A sixth aspect provides a data transmission method, which may be executed by a second network device, or may be executed by a component (such as a chip or circuit) of the second network device, which is not limited in this application. For convenience of description, the following description takes execution by the second network device as an example.

The method may include: the second network device sends second indication information to the terminal device, the second indication information is used to indicate to avoid data loss during the transmission of small data packets; the second network device sends fourth downlink data, the fourth The downlink data is small data; the second network device receives a first status report, the first status report includes indication information indicating that the terminal device has not successfully received the fourth downlink data; the second network device reports to the first network The device sends the fourth downlink data.

In conjunction with the sixth aspect, in some implementations of the sixth aspect, the second network device sends fourth downlink data, including: the second network device sends the fourth downlink data to the terminal device; the second network device Receiving the first status report includes: the second network device receives the first status report from the terminal device.

In conjunction with the sixth aspect, in some implementations of the sixth aspect, the method further includes: the second network device receiving a second request message from the first network device, the second request message being used to request acquisition of the terminal In the context of the device, the second request message includes instruction information for indicating small data packet transmission; the second network device sends a second response message to the second network device, the second response message includes instruction information for indicating execution anchor point Relocation instructions.

In conjunction with the sixth aspect, in some implementations of the sixth aspect, the second network device sends fourth downlink data, including: the second network device sends the fourth downlink data to a third network device; the second network device The device receiving the first status report includes: the second network device receiving the first status report from the third network device.

In conjunction with the sixth aspect, in some implementations of the sixth aspect, the method further includes: the second network device sending a fourth request message to the third network device, the fourth request message being used to request the fourth downlink data status report.

In conjunction with the sixth aspect, in some implementations of the sixth aspect, the method further includes: the second network device receiving a third request message from the first network device, the third request message being used to request acquisition of the terminal In the context of the device, the third request message includes instruction information for indicating small data packet transmission; the second network device sends a third response message to the first network device, the third response message includes instruction information for indicating not to execute the anchor. Click relocation instructions.

A seventh aspect provides a data transmission method, which can be executed by the first network device, or can also be executed by a component (such as a chip or circuit) of the first network device, which is not limited in this application. For convenience of description, the following description takes execution by the first network device as an example.

The method may include: the first network device sending first indication information to the terminal device, the first indication information being used to instruct the first network device to support avoiding data loss during small data packet transmission; the first network device receiving from The fourth downlink data of the second network device, the fourth downlink data is unsuccessfully received by the terminal device, and the fourth downlink data is small data; the first network device sends the fourth downlink data to the terminal device.

In conjunction with the seventh aspect, in some implementations of the seventh aspect, the method further includes: the first network device sending a second request message to the second network device, the second request message being used to request acquisition of the terminal device context, the second request message includes instruction information for indicating small data packet transmission; the first network device receives a second response message from the second network device, the second response message includes instruction information for indicating execution anchor point Relocation instructions.

In conjunction with the seventh aspect, in some implementations of the seventh aspect, the method further includes: the first network device sending a third request message to the second network device, the third request message being used to request acquisition of the terminal device In the context, the third request message includes indication information for indicating small data packet transmission; the first network device receives a third response message from the second network device, the third response message includes indication information for indicating not to execute the anchor Click relocation instructions.

Combined with the seventh aspect, in some implementations of the seventh aspect, the method further includes: the first network device sends a radio resource control release message to the terminal device, the radio resource control release message includes Y, where Y is small data The number of cell reselections during packet transmission, Y is a positive integer.

An eighth aspect provides a data transmission method, which may be executed by a second network device, or may be executed by a component (such as a chip or circuit) of the second network device, which is not limited in this application. For convenience of description, the following description takes execution by the second network device as an example.

The method may include: the second network device sends second indication information to the terminal device, the second indication information is used to indicate to avoid data loss during the transmission of small data packets; the second network device sends fourth downlink data, the fourth The downlink data is small data; the second network device receives a first status report, the first status report includes indication information indicating that the terminal device has not successfully received the fourth downlink data; the second network device reports to the first network The device sends the fourth downlink data.

In conjunction with the eighth aspect, in some implementations of the eighth aspect, the second network device sends fourth downlink data, including: the second network device sends the fourth downlink data to the terminal device; the second network device Receiving the first status report includes: the second network device receives the first status report from the terminal device.

In conjunction with the eighth aspect, in some implementations of the eighth aspect, the method further includes: the second network device receiving a second request message from the first network device, the second request message being used to request to obtain the terminal In the context of the device, the second request message includes instruction information for indicating small data packet transmission; the second network device sends a second response message to the second network device, the second response message includes instruction information for indicating execution anchor point Relocation instructions.

Combined with the eighth aspect, in some implementations of the eighth aspect, the second network device sends fourth downlink data, including: the second network device sends the fourth downlink data to a third network device; the second network device The device receiving the first status report includes: the second network device receiving the first status report from the third network device.

In conjunction with the eighth aspect, in some implementations of the eighth aspect, the method further includes: the second network device sending a fourth request message to the third network device, the fourth request message being used to request the fourth downlink data status report.

In conjunction with the eighth aspect, in some implementations of the eighth aspect, the method further includes: the second network device receiving a third request message from the first network device, the third request message being used to request acquisition of the terminal In the context of the device, the third request message includes instruction information for indicating small data packet transmission; the second network device sends a third response message to the first network device, the third response message includes instruction information for indicating not to execute the anchor. Click relocation instructions.

Combined with the eighth aspect, in some implementations of the eighth aspect, the method further includes: the first network device sends a radio resource control release message to the terminal device, the radio resource control release message includes Y, where Y is small data The number of cell reselections during packet transmission, Y is a positive integer.

The network device sends a radio resource control release message to the terminal device. The radio resource control release message includes Y, where Y is the number of cell reselections during small data packet transmission, and Y is a positive integer.

In the ninth aspect, a data transmission method is provided. The method can be executed by the first network device, or can also be executed by a component (such as a chip or circuit) of the first network device. This application is not limited to this. For convenience of description, the following description takes execution by the first network device as an example.

The method may include: the first network device sending first indication information to the terminal device, the first indication information being used to instruct the first network device to support avoiding data loss during small data packet transmission; the first network device receiving from The first uplink data of the second network device, the first uplink data is the data successfully received by the second network device, the first uplink data is small data; the first network device receives the second uplink data from the terminal device , the second uplink data is data from the terminal device that was unsuccessfully received by the second network device, and the second uplink data is small data.

In conjunction with the ninth aspect, in some implementations of the ninth aspect, the method further includes: the first network device sending a second request message to the second network device, the second request message being used to request acquisition of the terminal device In the context, the second request message includes instruction information for indicating small data packet transmission; the first network device receives a second response message from the second network device, the second response message is used to indicate the second network device Decided to perform anchor relocation.

In a tenth aspect, a data transmission method is provided. The method may be executed by a second network device, or may be executed by a component (such as a chip or circuit) of the second network device. This application is not limited to this. For convenience of description, the following description takes execution by the second network device as an example.

The method may include: the second network device sends second instruction information to the terminal device, the second instruction information is used to instruct to avoid data loss during the transmission of small data packets; the second network device receives a fourth uplink signal from the terminal device. data, the fourth uplink data is small data; the second network device sends a third status report to the terminal device, the third status report includes at least one of the following indication information: used to indicate successful reception of the first uplink data Instruction information used to indicate that the second uplink data has not been successfully received. The fourth uplink data includes the first uplink data and the second uplink data; the second network device sends the first uplink data to the first network device. Upstream data.

In conjunction with the tenth aspect, in some implementations of the tenth aspect, the method further includes: the second network device receiving a second request message from the second network device, the second request message being used to request to obtain the terminal In the context of the device, the second request message includes instruction information for instructing small data packet transmission; the second network device sends a second response message to the second network device, the second response message is used to instruct the second network device Decided to perform anchor relocation.

An eleventh aspect provides a data transmission method, which can be executed by a terminal device, or can also be executed by a component (such as a chip or circuit) of the terminal device, which is not limited in this application. For convenience of description, the following description takes execution by a terminal device as an example.

The method may include: the terminal device receives second indication information from the second network device, the second indication information is used to indicate to avoid data loss during the transmission of small data packets; the terminal device sends a fourth uplink to the second network device. data, the fourth uplink data is small data; the terminal device receives a third status report from the second network device, the third status report includes at least one of the following indication information: used to indicate successful reception of the first uplink Data indication information, indication information indicating unsuccessful reception of the second uplink data, wherein the fourth uplink data includes the first uplink data and the second uplink data; the terminal device receives the third uplink data from the first network device. An indication information, the first indication information is used to instruct the first network device to support avoiding data loss during small data packet transmission; the terminal device sends the second uplink data to the first network device.

A twelfth aspect provides a data transmission method, which can be executed by a terminal device, or can also be executed by a component (such as a chip or circuit) of the terminal device, which is not limited in this application. For convenience of description, the following description takes execution by a terminal device as an example.

The method may include: the terminal device receives a radio resource control release message from the network device, the radio resource control release message includes Y, Y is the number of cell reselections during the small data packet transmission process, and Y is a positive integer; the terminal device initiates Small data packet transmission process; the terminal equipment records the number of cell reselections; when the number of cell reselections recorded by the terminal equipment is ≥ Y, the terminal equipment switches to the radio resource control idle state, or the terminal equipment switches to the wireless resource control idle state. Network devices send resume request messages for non-small packet transfers.

The above scheme sets a threshold for the number of cell reselections of the terminal equipment, and the terminal equipment counts the number of cell reselections. When the number of cell reselections reaches the threshold, the cell reselection is stopped or switched to the idle state or initiates non-small data packets. The transmission recovery process reduces the reduction in communication efficiency caused by continuous small data packet transmission failures and improves communication efficiency.

A thirteenth aspect provides a data transmission device, which is used to perform the method in any of the possible implementation modes of the first to twelfth aspects. Specifically, the device may include units and/or modules for performing the method in any possible implementation of the first to twelfth aspects, such as a processing unit and/or a communication unit.

In one implementation, the device is a communication device (such as a network device or a terminal device). When the device is a communication device, the communication unit may be a transceiver, or an input/output interface; the processing unit may be at least one processor. Alternatively, the transceiver may be a transceiver circuit. Alternatively, the input/output interface may be an input/output circuit.

In another implementation manner, the device is a chip, chip system or circuit used in communication equipment (such as network equipment, such as terminal equipment). When the device is a chip, chip system or circuit used for communication equipment, the communication unit may be an input/output interface, interface circuit, output circuit, input circuit, pin or related circuit on the chip, chip system or circuit, etc. ; The processing unit may be at least one processor, processing circuit or logic circuit, etc.

A fourteenth aspect, a data transmission device is provided. The device includes: at least one processor for executing computer programs or instructions stored in a memory to execute any of the possible implementation methods of the first to twelfth aspects above. method in. Optionally, the device further includes a memory for storing computer programs or instructions. Optionally, the device further includes a communication interface, through which the processor reads the computer program or instructions stored in the memory.

In one implementation, the device is a communication device (such as a network device or a terminal device).

In another implementation manner, the device is a chip, chip system or circuit used in communication equipment (such as network equipment, such as terminal equipment).

In a fifteenth aspect, the present application provides a processor for executing the methods provided in the above first to twelfth aspects.

For operations such as sending and getting/receiving involved in the processor, if there is no special explanation, or if it does not conflict with its actual role or internal logic in the relevant description, it can be understood as processor output, reception, input and other operations. , can also be understood as the transmitting and receiving operations performed by the radio frequency circuit and the antenna, which is not limited in this application.

In a sixteenth aspect, a computer-readable storage medium is provided. The computer-readable medium stores a program code for device execution. The program code includes a possible implementation manner for executing any of the above-mentioned first to twelfth aspects. method in.

In a seventeenth aspect, a computer program product containing instructions is provided. When the computer program product is run on a computer, it causes the computer to execute the method in any of the possible implementation modes of the first aspect to the twelfth aspect.

In an eighteenth aspect, a communication system is provided, including the aforementioned first network device and second network device.

Description of the drawings

Figure 1 shows a schematic diagram of a communication system applying an embodiment of the present application.

Figure 2 shows a schematic diagram of data transmission between UE and gNB through the protocol stack.

Figure 3 (a) shows the protocol stack distribution in the scenario where the previous serving gNB decides not to perform anchor relocation. Figure 3 (b) shows the previous serving gNB decides to perform anchor relocation. Protocol stack distribution in positioning scenarios.

Figure 4 shows a schematic diagram of the data transmission method 100 provided by this application.

FIG. 5 shows a schematic diagram of the data transmission method 110 provided by this application.

Figure 6 shows a schematic diagram of the data transmission method 120 provided by this application.

Figure 7 shows a schematic diagram of the data transmission method 200 provided by this application.

Figure 8 shows a schematic diagram of the data transmission method 300 provided by this application.

Figure 9 shows a schematic diagram of the data transmission method 400 provided by this application.

Figure 10 shows a schematic flow chart of the data transmission method 500 provided by this application.

Figure 11 shows a schematic block diagram of a data transmission method 500 provided by this application.

FIG. 12 is a schematic diagram of a data transmission device 600 provided by an embodiment of the present application.

FIG. 13 is a schematic diagram of another data transmission device 700 provided by an embodiment of the present application.

Figure 14 is a schematic diagram of a chip system 800 provided by an embodiment of the present application.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be described in further detail below in conjunction with the accompanying drawings. The specific operation methods in the method embodiments can also be applied to the device embodiments or system embodiments.

The communication method provided by this application can be applied to various communication systems, for example, it can be the Internet of things (IoT), narrowband Internet of things (NB-IoT), long term evolution (long term evolution) , LTE), it can also be the fifth generation ( ^5th generation, 5G) communication system, it can also be a hybrid architecture of LTE and 5G, it can also be a 5G new radio (NR) system and 6G or what will appear in future communication development new communication systems, etc. The communication system described in this application may also be a machine-to-machine (M2M) network or other networks.

Figure 1 shows a schematic diagram of a communication system applying an embodiment of the present application. In the 5G system, the 5G access point consists of the next generation radio access network (NG-RAN) of the base station node. The NG-RAN node may be a 5G new base station node (generation nodeb, gNB), or It may be an LTE evolution base station node (next generation enodeb, ng-eNB). Among them, gNB uses NR's user plane and control plane protocol stack, while ng-eNB uses evolved universal terrestrial radio access (E- UTRA) user plane and control plane protocol stack.

gNB and gNB, ng-eNB and ng-eNB, gNB and ng-eNB are interconnected through the Xn interface. gNB and ng-eNB are connected to the 5G core network through the NG interface. The control plane is connected to the access network and mobility management function (AMF) through the NG-C interface, and the user plane is connected through the NG-U interface. To the user plane function (UPF) module.

In order to facilitate understanding of the embodiments of this application, some technical terms involved in this application are introduced below.

1. Radio resource control (RRC) status

The RRC state includes: Radio Resource Control connected state (RRC connected), Radio Resource Control idle state (RRCidle) or Radio Resource Control inactive state (RRC inactive).

Under RRC connected, there is a dedicated RRC connection between the terminal device and the access network device. This dedicated RRC connection is a connection of a data radio bearer (DRB) or a signaling radio bearer 1 (signal RadioBearer1, SRB1). In RRC idle, there is no dedicated RRC connection between the terminal equipment and the access network equipment.

Under RRC inactive, the terminal equipment moves under the RAN based notification area (RNA) without knowing the access network equipment. The terminal device saves its own context, and the last serving gNB (last serving gNB) saves the context of the terminal device, as well as the NG connection with AMF and UPF. The dedicated RRC connection between the terminal equipment and the access network equipment is suspended and can be restored later. The terminal device can perform cell reselection in RRC inactive.

Among them, RRC inactive can quickly restore the user equipment (UE) to RRCconnected without reconnecting. RRC inactive is similar to RRC idle. They can only receive content from the public search space (such as paging and broadcasting) and can perform cell reselection. RRC inactive can achieve a power consumption level similar to that of RRC idle state because the UE in RRC inactive will suspend data processing. If the UE moves in the same RNA, it does not need to exchange information with the gNB. However, if the UE moves out of the RNA range, the RNA update process needs to be started. The UE in RRC inactive mode can have a lower data transmission recovery delay because the UE in RRC inactive mode can quickly migrate to the RRC connected state through the RRC resume (resume) process.

2. Connection management (CM) status

The CM state consists of two parts: the establishment and release of the non-access stratum (NAS) signaling connection between the UE and the AMF. The NAS signaling connection is used for NAS signaling interaction between the UE and the core network. It includes two parts of connections: 1) The signaling connection between the UE and the access network (AN), such as the RRC connection in the 3rd generation partnership project (3GPP) access mode, non-3GPP Interworking function (non-3GPP interworking function, N3IWF), 2) N2 connection between AN and AMF.

3. Small data transmission (SDT) technology

Before the emergence of SDT, if the terminal device in the inactive state needs to transmit data packets, it must first trigger the RRC connection recovery process to switch to the connected state. SDT technology enables terminal equipment to transmit short data packets in an inactive state, avoiding the signaling overhead and energy consumption caused by frequently triggering the RRC connection recovery process.

There are many scenarios for SDT, which can specifically cover smartphone-related businesses, such as heartbeat packets or push messages of applications (APPs); and non-smartphone-related businesses, such as periodic data of wearable devices (such as heartbeats). packets), periodic data sent by industrial wireless sensor networks, etc. In addition, the specific size of small data may not be limited in the embodiments of the present application. For example, data packets of 100 to 300 bytes may be considered small data.

It can be understood that the data transmission and small data packet transmission described in the embodiments of this application below may refer to SDT, and the uplink data, downlink data and data packets described in the embodiments of this application may all be small data.

4. Protocol stack

In the 5G system, the protocol stack includes the following protocol layers: service data adaptation protocol (SDAP), packet data convergence protocol (PDCP), radio link control (RLC), Media access control (MAC), physical (PHY), different protocol layers have their own functions.

Figure 2 shows a schematic diagram of data transmission between UE and gNB through the protocol stack. When the UE is the sender, gNB is the receiver; when the UE is the receiver, gNB is the sender. Among them, the order of data processing on the sender side: SDAP->PDCP->RLC->MAC->PHY. After receiving the data, SDAP's main processing includes: mapping the quality of service (QoS) flow to the radio bearer (RB), and submitting the processed data to PDCP. The main processing of data in PDCP includes: encryption, integrity protection, header compression, adding PDCP serial number (SN), etc. The data of different RBs is obtained at the PDCP layer, and the terminal performs its own processing on different RBs. One logical channel corresponds to one RB, and the processed data is submitted to the RLC. The main processing of data in RLC: for acknowledgment mode (AM), automatic repeat-request (ARQ), segmentation, reassembly, adding RLC SN, for unacknowledged mode (UM), Segment, reassemble, add RLC SN. The processing of data in the MAC mainly includes the multiplexing of logical channels and hybrid automatic repeat-request (HARQ). A data packet is processed in the above order and finally sent out by the PHY. On the receiving side, work backwards in reverse order.

5. Window push timer

The following is an introduction based on the window push timer of the PDCP sending window. If the receiver's RLC determines that it has received a data packet, it will notify the receiver's PDCP through internal implementation so that PDCP can maintain the PDCP receiving window. If the RLC feedback of a data packet is an acknowledgment (ACK), then the PDCP receiving window can be pushed forward. Otherwise, the window remains unchanged, waiting for the sender to retransmit the data packet and starting the window pushing timer. . When the window push timer times out, regardless of whether the data packet is retransmitted or whether the retransmitted data packet is successfully received, the receiver's PDCP will push the PDCP receive window to prevent the PDCP receive window from getting stuck in a certain position. The receiver indicates the RLC status to the sender, and the sender maintains the PDCP sending window according to the instructions of the receiver. The maintenance method is similar to that of the receiver. For example, the current sending window of PDCP is [0,99], that is to say, PDCP is waiting to send packets with PDCP SN numbers from 0 to 99. In one implementation, assuming that RLC indicates that packets with PDCP SNs 0 and 1 are successfully received, then the PDCP sending window can be pushed forward to [2,101]. In another implementation, if the window push timer times out, the sending window can also be pushed to [2,101]. Moreover, when the window is pushed to [2,101], the sender will no longer resend data packets with PDCP SNs of 0 and 1.

6. Scenario in which anchor point gNB needs to decide whether to perform anchor point relocation

The UE communicates with the network through a gNB. The gNB configures an identity for the UE, such as a wireless network temporary identity. The gNB also configures an RNA for the UE. When the UE moves within the RNA, if it needs to transmit a small amount of data, it can transmit small data packets with the network. Then it is necessary to establish connections with other gNBs within the range of the RNA through the random access process of small data packet transmission. For example, in this application, the gNB that configures RNA for the UE is called the previous serving gNB, and other gNBs within the range of the RNA are called receiving gNBs. Moreover, as long as the receiving gNB receives the identifier from the UE, it can determine according to the identifier to request the context of the UE from the previous serving gNB.

Specifically, during the random access process of small data packet transmission, when the terminal equipment (user equipment, UE) is not within the coverage of the previous serving gNB after moving, it can access the network through the receiving gNB. The UE sends an RRC resume request message (RRC resume request) to the receiving gNB. The RRC recovery request message carries the identifier, which is allocated by the previous serving gNB. After receiving the RRC recovery request message, the receiving gNB sends a retrieve UE context request message (retrieve UE context request) to the previous serving gNB (last serving gNB) according to the identifier. The previous serving gNB decides whether to perform anchor point relocation after receiving the Get UE Context Request message. For example, the previous serving gNB may decide whether to perform anchor point relocation based on its own load, or may decide whether to perform anchor point relocation based on the information provided by the received gNB.

Optionally, before the terminal device initiates a small data packet transmission process to the receiving gNB, or before the terminal device sends an RRC recovery request message to the receiving gNB, the terminal device may also perform cell reselection to the cell where the receiving gNB is located.

7. Protocol stack distribution in the scenario where anchor point relocation is not performed

In the scenario where the previous serving gNB decides not to perform anchor relocation (without anchor relocation), the protocol stack distribution is as shown in (a) in Figure 3. The arrow represents the transmission path of the first data, and the first data may be user data or a non-access stratum (non-access stratum, NAS) message. The UE sends the first data to the receiving gNB, and then the receiving gNB sends the first data to the previous serving gNB through the Xn interface. The previous serving gNB is the anchor gNB. The UE sends the first data in the order of SDAP->PDCP->RLC->MAC->PHY. After receiving the first data in the order of PHY->MAC->RLC, the receiving gNB forwards the next data based on the RLC service data unit through the Xn interface. The serving gNB sends the first data.

8. Protocol stack distribution in the scenario where anchor point relocation is not performed

In the scenario where the previous serving gNB decides to perform anchor relocation (with anchor relocation), the protocol stack distribution is shown in (b) of Figure 3. The arrows represent the transmission path of user data or non-access stratum (non-accessstratum, NAS) messages. The UE sends the first data in the order of SDAP->PDCP->RLC->MAC->PHY, and the receiving gNB receives the first data in the order of PHY->MAC->RLC->PDCP->SDAP. Among them, the anchor point gNB is the receiving gNB.

Currently, during the above-mentioned SDT process, packet loss may occur. Therefore, how to reduce the packet loss rate is an issue that needs to be solved urgently. It should be noted that in the embodiment of the present application, in the scenario where anchor point relocation is not performed (such as method 200 and method 500), the anchor point gNB is the previous serving gNB. For example, the UE can communicate with the anchor point by accepting the gNB. Point gNB communication; in the scenario of performing anchor point relocation (for example, method 300 and method 400), the anchor point gNB is the receiving gNB. For example, the UE can directly communicate with the anchor point gNB.

The data transmission method provided by this application will be introduced below with reference to Figures 4 to 11. Next, methods 100, 110, and 120 will be introduced respectively with reference to Figures 4, 5, and 6. At least two of methods 100, 110, and 120 can be combined, and the application does not limit the order of execution. At least one of methods 100, 110, and 120 may also be combined with method 600.

Figure 4 shows a schematic diagram of the data transmission method 100 provided by this application.

S101. The second network device sends first downlink data to the first network device. Correspondingly, the first network device receives the first downlink data from the second network device, and the first downlink data is small data.

For example, the first network device and the second network device may be two gNBs in the same RNA, and the second network device saves the context of the terminal device. For example, the first network device may be the receiving gNB, and the second network device may be the previous serving gNB. For another example, the protocol stack distribution of the terminal device, the first network device, and the second network device can be seen in (a) in Figure 3 .

Exemplarily, the second network device sends the first downlink data to the second network device based on the packet data convergence layer.

Optionally, before S101, the first network device sends a first request message to the second network device. The first request message is used to request to obtain the context of the terminal device, and the first request message includes instruction information used to instruct small data packet transmission. ; The first network device receives a first response message from the second network device, where the first response message includes indication information indicating not to perform anchor point relocation. It can be understood that the second network device is still the anchor gNB, the RLC, MAC, and PHY in the protocol stack are migrated to the first network device, and PDCP and SDAP are still on the second network device, such as (a) in Figure 3 Show. In addition, the second response message includes the SDT context. For an introduction to the SDT context, please refer to S204 of the method 200.

S102: The first network device sends first downlink data to the terminal device, and accordingly, the terminal device receives the first downlink data from the first network device.

Exemplarily, the first network device sends the first downlink data to the terminal device based on the radio link control layer.

S103. The terminal device sends a first feedback message to the first network device. Correspondingly, the first network device receives the first feedback message from the terminal device. The first feedback message is used to indicate successful or unsuccessful reception of the first downlink data. The feedback message corresponds to the first protocol layer.

Exemplarily, the first protocol layer is a radio link control layer.

Exemplarily, the first feedback message includes at least one of the following: the sequence number of the first downlink data in the radio link control layer, the identification of the radio bearer carrying the first downlink data, and the logical channel carrying the first downlink data. logo.

S104. The first network device sends a second feedback message to the second network device according to the first feedback message. Correspondingly, the second network device receives the second feedback message from the first network device, and the second feedback message corresponds to the second feedback message. protocol layer. When the first feedback message is used to indicate that the first downlink data is successfully received, the second feedback message is used to indicate that the terminal device successfully receives the first downlink data. Alternatively, the first feedback message is used to indicate that the first downlink data has not been successfully received, and the second feedback message is used to indicate that the terminal device has not successfully received the first downlink data.

Illustratively, the second protocol layer is a packet data convergence layer.

Exemplarily, the second feedback message includes at least one of the following: the sequence number of the first downlink data at the packet data convergence layer, the sequence number of the first downlink data at the radio link control layer, the sequence number carrying the first downlink data. The identifier of the radio bearer and the identifier of the logical channel carrying the first downlink data.

Regarding when to execute S104, there can be two different implementations.

Implementation method 1: The first network device sets a timer, and executes S104 when the timer times out.

The start time of the timer may be the time when the first network device receives a feedback message corresponding to downlink data. The feedback message here is used to indicate successful or unsuccessful reception of the one downlink data. The one downlink data may be the first downlink data, or may be downlink data other than the first downlink data. For example, the timing duration of the timer may be preconfigured or determined by the first network device or the second network device.

For specific examples, see Implementation Mode 1 in S212.

Implementation manner 2: The first network device determines according to the first feedback message that the data of the wireless link control layer successfully received by the terminal device includes at least N pieces of data with consecutive sequence numbers, and the N pieces of data include the first downlink data, and performs S104. In other words, every time the first network device determines that the sequence numbers of N pieces of data are consecutive, it can indicate to the second network device that N pieces of data have been successfully received, and the N pieces of data include the first downlink data.

Exemplarily, in step 1, the first network device determines according to the first feedback message that the terminal device successfully receives M pieces of data of the first protocol layer, where M is a positive integer, and the M pieces of data include first downlink data.

It should be understood that these M data do not include data that the first network device has indicated to the second network device and that the terminal device has successfully received. In other words, the first network device has not indicated successful reception to the second network device. M data. For example, in addition to receiving the first feedback message, the first network device may also receive feedback message A. Feedback message A is used to indicate successful reception of downlink data A, where downlink data A is downlink data other than the first downlink data. The M pieces of data include the first downlink data and downlink data A.

Step 2: When the number of data with consecutive sequence numbers among the M pieces of data is greater than or equal to N, the first network device sends a second feedback message to the second network device. The second feedback message Used to indicate that the terminal device successfully receives N pieces of data of the second protocol layer, where the N pieces of data include the first downlink data, and the N is a positive integer.

It should be understood that the M pieces of data are sorted according to the sequence number of the second protocol layer corresponding to each data. When the sequence numbers of N pieces of data among the M pieces of data are consecutive, the first network device can send the sequence number to the second network device. Second feedback message.

For example, the N pieces of data indicated in the second feedback message are the first N pieces of data arranged in ascending order from the sequence numbers of the packet data aggregation layer of the M pieces of data.

For specific examples, see Implementation Mode 2 in S212.

S105. The second network device determines the second sending window based on the first sending window and the second feedback message. The first sending window contains the sequence number of the first downlink data. When the second feedback message indicates that the first downlink data is successfully received, In this case, the second sending window contains the sequence number of the downlink data that has not been sent to the terminal device.

For example, when the second feedback message indicates that the first downlink data is not successfully received, the second network device may not adjust the first sending window. In other words, the first sending window and the second sending window are consistent.

Exemplarily, in the case where the second feedback message indicates successful reception of the first downlink data, the second network device determines according to the second feedback message that the data corresponding to the first L sequence numbers of the first sending window has been successfully received by the terminal device. , L is a positive integer, then the determined starting sequence number of the second sending window is equal to the sequence number corresponding to the L+1th data of the first sending window,

Optionally, corresponding to implementation mode 2 in S104, L may also be equal to N.

For specific examples, see the description in S213.

For example, method 200 can be understood as a possible implementation of method 100.

In the above solution, during the small data packet transmission process, the first network device sends a second feedback message to the second network device (anchor gNB). The second feedback message indicates whether the terminal device has successfully or unsuccessfully received the first downlink data. , the second network device can decide how to adjust the PDCP sending window based on the feedback message. The embodiment of the present application enables the anchor point gNB to obtain the RLC status of the terminal device through interaction between network devices, so that it can push data based on the data successfully received by the terminal device. PDCP sending window to reduce packet loss rate.

FIG. 5 shows a schematic diagram of the data transmission method 110 provided by this application.

S111. The second network device sends second indication information to the terminal device. Correspondingly, the terminal device receives the second indication information from the second network device. The second indication information is used to indicate whether to allow/use the small data packet during transmission. Data loss can be avoided.

For example, the second indication information may be carried in the RRC release message, or may also be carried in other messages, which is not limited in this application. The RRC release message carries a displayed indication information, which can instruct the terminal device to enter the RRC inactive state.

The second indication information can also be understood as being used to indicate to the terminal device that if SDT fails, such as cell reselection, during the subsequent SDT process, the second network device supports a mechanism to avoid the loss of uplink data. Specifically, this mechanism Subsequent steps in method 110 are included. For example, the second indication information here can be expressed as a flag to enable avoidance of data loss, or it can also be other expression methods with similar functions, which is not limited by this application.

S112, S113 and S114 can be implemented in multiple ways. For example, in scheme 1, S112-a, S113 is S113-a, and S114 is S114-a, or in scheme 2, S112 is S112-b-1 and S112-b. -2, S113 is S113-b-1 and S113-b-2, and S114 is S114-b.

For example, in solution 1, the second network device directly sends the fourth downlink data to the terminal device, and accordingly, the terminal device directly receives the fourth downlink data from the second network device. The terminal device directly feeds back the status report corresponding to the fourth downlink data to the second network device. Correspondingly, the second network device directly receives the status report corresponding to the fourth downlink data from the terminal device. And the first network device is the anchor gNB. In solution 2, the second network device sends the fourth downlink data to the terminal device indirectly (through other devices), and accordingly, the terminal device receives the fourth downlink data from the second network device indirectly (through other devices). The terminal device indirectly (through other devices) feeds back the status report corresponding to the fourth downlink data to the second network device. Correspondingly, the second network device indirectly (through other devices) receives the status report corresponding to the fourth downlink data from the terminal device. The first network device is not the anchor gNB.

It can be understood that in solution 2, the second network device can send the fourth downlink data to the terminal device through the third network device, and the terminal device can also feed back the second status report to the third network device first, and then the third network device can Send the first status report to the second network device according to the second status report. In a possible implementation, the third network device and the second network device may be two gNBs in the same RNA, and the second network device saves the context of the terminal device. For example, the third network device may be the receiving gNB, and the second network device may be the previous serving gNB. For a possible implementation method, please refer to the corresponding description in 500. It should be noted that the subsequent steps of Solution 2 involve the terminal device performing cell reselection and reselecting to the cell of the first network device. Then the first network device can be the receiving gNB, and the second network device can be the previous service. gNB. In order to distinguish the third network device from the first network device, the third network device here is called the previous receiving gNB in the method 500, and the first network device is called the receiving gNB.

plan 1:

S112-a: The second network device sends fourth downlink data to the terminal device. Correspondingly, the terminal device receives the fourth downlink data from the second network device, and the fourth downlink data is small data.

S113-a. The terminal device sends a first status report to the second network device. Correspondingly, the second network device receives the first status report from the terminal device. The first status report is used to indicate that the fourth downlink data has not been successfully received.

For example, the first status report here may correspond to the radio link control layer.

It should be noted that S113-a does not limit the first status report to indicating unsuccessfully received downlink data to the second network device. Here, the unsuccessful reception of the fourth downlink data is used as an example to introduce how the embodiment of the present application Reduce packet loss rate. For example, the first status report may also indicate that the terminal device successfully receives downlink data B, and the downlink data B is also sent to the terminal device by the second network device.

S114-a. The first network device sends the first instruction information to the terminal device. Correspondingly, the terminal device receives the first instruction information from the first network device. The first instruction information is used to instruct the first network device to support small data packets. Avoid data loss during transfer.

For example, before S114-a, the SDT process of the terminal device fails. Optionally, before S114-a, method 110 may also include the terminal device performing cell reselection to the cell where the first network device is located.

It should be understood that the first indication information can be understood as, in the subsequent steps of S114-a, if the terminal device wants to communicate with the network device through the first network device, the first network device can support avoiding the connection between the terminal device and the network before SDT fails. Data transferred between sides is lost.

It can be understood that, when the first network device supports avoiding data loss during small data packet transmission, the first network device sends the first indication information to the terminal device. For example, when the first network device does not support avoiding data loss during small data packet transmission, the first network device may send indication information A to the terminal device, and the indication information A is used to indicate that data loss during small data packet transmission is not supported. Data loss is avoided during packet transmission, or the first network device does not send the first indication information or indication information A. In this case, the terminal device can perform cell reselection again, reselect to a cell of other network devices, and repeat steps similar to S114-a; or, the terminal device can enter the RRC idle state, and optionally, the terminal device initiates Recovery process for non-SDT processes.

Optionally, after S114-a, the first network device may obtain the subscription data of the terminal device according to the identifier carried by the terminal device and send a second request message to the second network device, where the second request message is used to request to obtain the terminal device. The context of the device, the second request message includes instruction information for indicating small data packet transmission; the first network device receives a second response message from the second network device, the second response message includes Instructions for performing anchor relocation. It can be understood that the anchor point is relocated from the second network device to the first network device, and the protocol stack is migrated from the second network device to the first network device, for example, as shown in (b) in FIG. 3 . In addition, the second response message includes the context of the terminal device. Then the first network device performs an SDT process with the terminal device according to the context of the terminal device, and the first network device saves the context of the terminal device at the PDCP layer.

Optionally, the first network device receives fourth indication information from the second network device. Correspondingly, the second network device receives fourth indication information from the first network device. The fourth indication information is used to indicate that the terminal device has not Successfully received the fourth downlink data. The first network device determines the sending window of PDCP according to the fourth indication information. The method of determining the PDCP transmission window may refer to the description in S414. In a possible implementation, the fourth indication information is carried in the second response message, or the fourth indication information is implicitly indicated by S115, or the fourth indication information is transmitted together with the fourth downlink data.

Scenario 2:

S112-b-1: The second network device sends fourth downlink data to the third network device. Correspondingly, the third network device receives the fourth downlink data from the second network device, and the fourth downlink data is small data.

S112-b-2: The third network device sends fourth downlink data to the terminal device, and accordingly, the terminal device receives the fourth downlink data from the third network device.

S113-b-1. The terminal device sends a second status report to the third network device. Correspondingly, the third network device receives the second status report from the terminal device. The second status report is used to indicate that the fourth downlink data has not been successfully received. .

For example, the second status report here may correspond to the radio link control layer.

S114-b, for details, please refer to the description of S114-a in Solution 1. The difference is that the optional steps after S114-a are different from the optional steps after S114-b.

Optionally, after S114-b, the first network device may obtain the subscription data of the terminal device according to the identifier carried by the terminal device and send a third request message to the second network device, where the third request message is used to request to obtain the terminal device. The context of the device, the third request message includes instruction information for indicating small data packet transmission; the first network device receives a third response message from the second network device, the third response message includes Instructions to not perform anchor relocation. It can be understood that the second network device is still the anchor gNB, the RLC, MAC, and PHY in the protocol stack are migrated to the first network device, and PDCP and SDAP are still on the second network device, such as (a) in Figure 3 Show. In addition, the third response message includes the SDT context. For an introduction to the SDT context, please refer to S515 of the method 500.

It should be noted that S114 precedes S113-b-2, or may also precede S113-b-2.

S113-b-2. The third network device sends the first status report to the second network device. Correspondingly, the second network device receives the first status report from the third network device. The first status report includes instructions for instructing the terminal device. Indication information indicating that the fourth downlink data was not successfully received.

For example, the second status report here may correspond to the packet data aggregation layer.

As an example, S113-b-1 and S113-b-2 may refer to S103 and S104 in the method 100 respectively.

As another example, before S113-b-2, in step 1, the second network device sends a fourth request message to the third network device, and accordingly, the third network device receives the fourth request message from the first network device. The fourth request message is used to request a fourth downlink data status report. The first status report in S113-b-2 is carried in the response message of the request message. Optionally, step 1 may be performed before the terminal equipment cell is reselected to the cell of the first network equipment, or after the terminal equipment cell is reselected to the cell of the first network equipment. For example, after the terminal device is cell-reselected to the cell of the first network device, the third request message in S114 may be understood as a trigger condition that triggers the second network device to perform step 1.

Optionally, the second network device may also determine the PDCP transmission window after cell reselection based on the first status report. For details, see the example given in S513.

S115. The second network device sends fourth downlink data to the first network device. Correspondingly, the terminal device receives the fourth downlink data from the first network device.

S116: The first network device sends fourth downlink data to the terminal device, and accordingly, the terminal device receives the fourth downlink data from the first network device.

It should be understood that in S115 and S116, the second network device retransmits the fourth downlink data to the terminal device through the first network device.

It should also be understood that during the SDT process, when cell reselection occurs on the terminal equipment, the terminal equipment will enter the RRC idle state and will no longer transmit data packets, and packet loss is likely to occur. In the embodiment of the present application, after SDT fails, the unsuccessfully received data is retransmitted to the terminal device, so that the terminal device can obtain the data that was successfully received before SDT failed, thereby reducing the packet loss rate in the SDT process.

Optionally, after receiving the fourth request message, the third network device may release the link with the terminal device and stop communicating with the terminal device. It should be noted that there is no restriction here that the next step of the third network device after receiving the fourth request message is to release the link with the terminal device and stop communicating with the terminal device.

For example, method 400 can be understood as a possible implementation of solution 1 of method 110, and method 500 can be understood as a possible implementation of solution 2 of method 110.

Figure 6 shows a schematic diagram of the data transmission method 120 provided by this application.

S121. The second network device sends second indication information to the terminal device. Correspondingly, the terminal device receives the second indication information from the second network device. The second indication information is used to indicate whether to allow/use the small data packet during transmission. Data loss can be avoided.

For details, please refer to the corresponding description in S111. The difference lies in replacing "Method 110" with "Method 120".

S122: The terminal device sends fourth uplink data to the second network device. Correspondingly, the second network device receives the fourth uplink data from the terminal device, and the fourth uplink data is small data.

S123. The second network device sends a third status report to the terminal device. Correspondingly, the terminal device receives the third status report from the second network device. The third status report includes at least one of the following indication information: used to indicate success. Instruction information for receiving the first uplink data is used to indicate that the second uplink data has not been successfully received. The fourth uplink data includes the first uplink data and the second uplink data.

It should be understood that the terminal device can determine which data in the fourth uplink data has been successfully received and which data has not been successfully received according to the third status report.

For example, the third status report here may correspond to the radio link control layer.

S124. The first network device sends the first indication information to the terminal device. Correspondingly, the terminal device receives the first indication information from the first network device. The first indication information is used to instruct the first network device to support the small data packet transmission process. to avoid data loss.

For details, please refer to the corresponding description in S114. The difference is: replace "S114" with "S124" and replace "Method 120" with "S110".

S125. The second network device sends the first uplink data to the first network device. Correspondingly, the first network device receives the first uplink data from the second network device. The first uplink data is data successfully received by the second network device. The first uplink data is small data.

It should be understood that since the anchor point is relocated to the first network device, the second network device also sends data that has been successfully received from the terminal device before the SDT fails to the first network device.

S126. The terminal device sends second uplink data to the first network device. Correspondingly, the first network device receives the second uplink data from the terminal device. The second uplink data is data from the terminal device that the second network device fails to receive. , the second uplink data is small data.

Illustratively, the terminal device retransmits the data that the second network device failed to receive to the first network device according to the third status report received in S123. It can be understood that through S125 and S126, the first network device can successfully receive the fourth uplink data sent by the terminal device to the second network device in S122.

For example, method 300 can be understood as a possible implementation of method 120.

It should be understood that during the SDT process, when cell reselection occurs on the terminal equipment, the terminal equipment will enter the RRC idle state and will no longer transmit data packets, and packet loss is likely to occur. In the embodiment of the present application, after SDT fails, the terminal device retransmits the data that was not successfully received by the second network device, and sends the data that has been successfully received from the terminal device to the first network device through the second network device, so that the first The network device can obtain the data sent by the terminal device to the second network device before SDT failed, thereby reducing the packet loss rate during the SDT process.

Figure 7 shows a schematic diagram of the data transmission method 200 provided by this application. The method 200 is introduced below by taking the first network device as the receiving gNB (receiving gNB), the second network device as the last serving gNB (last serving gNB), and the first downlink data as the first downlink SDT data. In method 200, the UE may move out of the coverage area of the second network device and access the network through the first network device. The UE initiates the SDT recovery process, and the first network device requests the context of the UE from the second network device. In a scenario where the second network device decides not to perform anchor point relocation, the first network device provides the RLC status to the second network device so that the second network device adjusts the PDCP sending window according to the RLC status. For the protocol stack distribution of the UE, the first network device and the second network device, see (a) in Figure 3 .

S201, the terminal device sends an RRC resume request (RRC resume request) message and uplink SDT data (UL SDT data) to the first network device. Correspondingly, the first network device receives the RRC resume request and uplink SDT data 01 from the terminal device. The first network device caches the uplink SDT data.

Alternatively, the uplink SDT data in S201 can also be replaced by uplink SDT signaling (UL SDT signaling).

S202: The first network device sends a retrieve UE context request message to the second network device. Correspondingly, the second network device receives the context request message from the first network device. The request message includes SDT indication information (SDT indicator).

S203. The second network device determines not to perform anchor point relocation.

For example, the second network device may determine not to perform anchor point relocation based on information such as its own load, or based on information received from the first network device.

S204. The second network device sends an SDT context transfer message to the first network device. Correspondingly, the first network device receives the SDT context transfer message from the second network device. The message includes the SDT context and the downlink data forwarding proposal. (DL data forwarding proposal) and DRB level uplink transport network layer information (DRB level DL transport network layer information).

Optionally, the message indicates that the second network device does not perform anchor relocation.

The second network device also sends an RLC configuration to the first network device. Correspondingly, the first network device receives an RLC configuration from the second network device, the RLC configuration corresponding to not performing anchor point relocation.

The second network device also sends the uplink data forwarding tunnel address to the first network device. Correspondingly, the first network device receives the uplink data forwarding tunnel address from the second network device. The first network device may forward the uplink data received from the UE to the second network device according to the uplink data forwarding tunnel address.

S205. The first network device sends XN-U ADDRESSINDICATION to the second network device to indicate the downlink data forwarding tunnel address. Correspondingly, the first network device receives the uplink address from the first network device. Indication information, which includes DRB-level uplink transmission network layer information. The second network device may send the downlink data to be sent to the UE to the first network device according to the downlink data forwarding tunnel address, and then the first network device forwards the downlink data to the UE.

S206: The first network device uses the uplink data forwarding tunnel address to send uplink SDT data to the second network device. Correspondingly, the second network device receives the uplink SDT data from the first network device. For example, the uplink data forwarding tunnel address here may be received in S204.

S207. The second network device sends uplink SDT data to the UPF. Correspondingly, the UPF receives the uplink SDT data from the second network device.

Optionally, S208, the UPF sends the second downlink SDT data to the second network device, and accordingly, the second network device receives the second downlink SDT data from the UPF. When S208 is executed, the second network device in S209 processes the second downlink SDT data and obtains the PDCP PDU including the first downlink SDT data; when S208 is not executed. The first downlink SDT data in S209 may be cached internally by the second network device.

S209. The second network device uses the downlink data forwarding tunnel address (received in S205) to send the PDCP PDU including the first downlink SDT data to the first network device. Correspondingly, the first network device receives the PDCP from the second network device. PDU. The first network device processes the PDCP PDU and obtains an RLC PDU, where the RLC PDU includes the first downlink SDT data.

S210: The first network device sends the RLC PDU to the UE, and accordingly, the UE receives the RLC PDU from the first network device.

S211. The UE sends the RLC status of the RLC PDU to the first network device. Correspondingly, the first network device receives the RLC status from the UE. The RLC status is used to indicate successful reception or unsuccessful reception of the first downlink SDT data.

For example, the UE successfully receives the first SDT data but fails to receive the second SDT data. The UE may report the RLC status to the first network device by sending an RLC feedback (feedback) message. In the RLC feedback message, ACK indicates successful reception of the first downlink SDT data, and non-acknowledgement (NACK) indicates unsuccessful reception of the first downlink SDT data. A row of SDT data. The RLC status here can be understood as a specific example of the first feedback message in the method 100.

S212. The first network device sends the RLC status of the PDCP PDU to the second network device. Correspondingly, the second network device receives the RLC status from the first network device. The RLC status here can be understood as a specific example of the second feedback message in the method 100.

The RLC state may carry the PDCP SN of the first downlink SDT data. Optionally, the RLC status may also carry an RB identifier. It should be understood that the PDCP SN of the downlink SDT data carried by the same RB may be the same, and the RB identifier carried can more accurately identify the first downlink SDT data.

Illustratively, the RLC status is transmitted through a control plane message.

For example, the first network device may report the RLC status to the first network device by sending an RLC feedback message. In the RLC feedback message, ACK indicates that the UE successfully received the first downlink SDT data, and NACK indicates that the UE did not successfully receive the first downlink SDT data. SDT data.

Regarding when to execute S212, there are several ways to implement it:

Implementation method one:

The first network device sets a timer. When the timer expires, the first network device feeds back the RLC status to the second network device, for example, performs S212. The timer may be started after the first network device performs S211, or alternatively, It may be started after the first network device receives other RLC status reports. The timing duration of the timer may be determined by the first network device. For example, other RLC status reports here may indicate that the third downlink SDT data is successfully received, and the third downlink SDT data is different from the first downlink SDT data.

It should be noted that the timer here is different from the window push timer mentioned in the technical terminology section above. The window push timer is at the anchor point gNB (the second network device in method 200). Its function is that when the window push timer times out, the anchor gNB will push the PDCP sending window. The timer here is not on the anchor point gNB, but on the first network device. The function of this timer is that when the timer times out, the first network device will feed back the RLC status to the second network device.

Implementation method two:

The terminal device sends the RLC status of one or more RLC PDUs to the first network device, and accordingly, the first network device receives the RLC status of the one or more RLC PDUs from the terminal device. The first network device determines that the terminal device has successfully received M PDCP PDUs based on the RLC status of the one or more RLC PDUs. When M≥N, or in other words, the first network device determines based on the RLC status of the one or more RLC PDUs. When the RLC status determines that the number of PDCP PDUs successfully received by the terminal device has reached a first threshold, for example, the first threshold is N, then the first network device sends the RLC status of N PDCP PDUs to the second network device. Among them, N is a positive integer.

The N here may be indicated by the second network device, and the N here may be understood as a threshold, such as the first threshold. For example, the second network device may indicate to the first network device in step S204.

Compared with the method in which the first network device sends the RLC status of a PDCP PDU to the second network device every time it determines that the terminal device successfully receives an RLC PDU, the second implementation method can reduce signaling overhead.

Optionally, the PDCP SNs of the N PDCP PDUs are consecutive.

For example, the sending window when the second network device sends the first SDT data is [1,99], N is 3, and the PDCP SN of the first SDT data is 3. The one or more RLC statuses are also used to indicate the success of the terminal device. After receiving SDT data A and SDT data B, the PDCP SN of SDT data A is 2, and the PDCP SN of SDT data B is 1, then the RLC status sent by the first network device to the second network device indicates that N PDCPs were successfully received. PDU.

The case where the SNs of the PDCP PDUs sent by the first network device to the second network device are consecutive may be that the first network device determines that the terminal device successfully received 0, 1, 2, 3, and 4 based on the RLC status of the multiple RLC PDUs. Then the first network device can adjust the starting SN of the PDCP sending window to 5 in S213.

S213: The second network device pushes the PDCP sending window according to the RLC status received in S212.

For example, the PDCP sending window before executing S213 is called the first sending window, and the PDCP sending window after executing S213 is called the second sending window. The first sending window includes the PDCP SN of the first SDT data, for example, before pushing The sending window is [1,99], and the PDCP SN of the first SDT data before pushing is 3. Before the second network device executes S213, it needs to determine how many bits to push the PDCP transmission window forward. In other words, it needs to determine the starting SN of the pushed PDCP transmission window. The starting SN here may be the data whose PDCP SN is ranked first among the data that has not been successfully received by the terminal device in the first sending window. For example, if the data whose PDCP SNs are 4, 6-8, and 10-99 in [1,99] are not successfully received by the terminal device, then the starting SN can be 4. Alternatively, the starting SN here may be the next PDCP SN of the consecutive data of the first L PDCP SNs among the data successfully received by the terminal device in the first sending window. For example, in [1,99], the data whose PDCP SNs are 1, 2, 3, 5, 6, and 7 are successfully received by the terminal device, and the starting SN can be 4.

Further, the second terminal device may determine the range of the PDCP sending window, that is, the starting SN and the ending SN of the sending window. The end SN of the transmission window can be calculated in the following way: the sum of the starting SN and the length of the transmission window is modulated by the length of the SN, and the remainder is the end SN. For example, the starting SN of the PDCP sending window is 5. Assume that the length of the sending window is 4 bits and the length of the SN is 8 bits. The sum of the starting SN and the length of the sending window is 9. 9 pairs The remainder of 8 is 1, then the last SN is 1 of the next SN period.

For example, the PDCP SN mentioned here can also be identified in binary. 0 can be represented as 00001, 1 can be represented as 0001, 2 can be represented as 0010, 3 can be represented as 0011, and 4 can be represented as 0100. The PDCP SNs involved in this application can all be expressed in the above manner, which will be described uniformly here, and will not be described in detail in other places.

S214: The second network device sends a failure message to obtain the UE context to the first network device. Correspondingly, the first network device receives a failure message to obtain the UE context from the second network device.

For example, this message may be carried in an RRC release message.

S215: The first network device sends an RRC release message to the terminal device. Correspondingly, the terminal device receives the RRC release message from the first network device. Subsequently, the terminal device terminates the SDT process.

In the above solution, through the exchange of RLC status reports between gNBs, that is, the first network device sends an RLC status report to the second network device (anchor gNB), and the second network device can decide how to adjust the PDCP transmission window based on the RLC status of the UE, thereby The embodiment of this application provides a solution for when the anchor gNB pushes the PDCP window.

Figure 8 shows a schematic diagram of the data transmission method 300 provided by this application. In the following, the first network device is the receiving gNB (receiving gNB), the second network device is the last serving gNB (last serving gNB), the first uplink data is data 1 and 3, and the second uplink data is data 2 and 4. The third uplink data is data 5, 6, 7, and 8 and the fourth uplink data is uplink SDT data. The method 300 is introduced as an example. In method 300, the UE performs cell reselection after sending uplink data to the second network device, and reselects the cell to the first network device. The UE initiates the SDT recovery process, and the first network device requests the context of the UE from the second network device. In the scenario where the second network device decides to perform anchor point relocation, the second network device provides the RLC status to the first network device, so that the first network device adjusts the PDCP receiving window according to the RLC status, and the first network device can successfully receive the UE Retransmitted uplink data reduces the packet loss rate of uplink data. The protocol stack distribution of the UE, the first network device and the second network device can be seen in (b) in Figure 3 .

S301. The second network device sends an RRC release message to the UE. Correspondingly, the UE receives the RRC release message from the second network device. The message includes second indication information, and the second indication information is used to indicate allowing/enabling data loss avoidance during the SDT process. The second indication information can also be understood as indicating to the UE that during the subsequent SDT process, if cell reselection occurs, the second network device supports a mechanism to avoid the loss of uplink data. Specifically, the mechanism includes steps S302-S319. . For example, the second instruction information here may be represented as a flag to enable avoidance of data loss.

S302, the UE initiates the SDT process, and the UE sends an RRC resume request 1 (RRC resumerequest) message to the second network device. Correspondingly, the second network device receives the RRC resume request 1 message from the UE. The RRC recovery request 1 message includes a first recovery (resume) message authentication code-integrity (message authentication code-integrity, MAC-I).

The UE and the first network device start the SDT failure detection timer. If the failure detection timer times out, the UE's RRC enters the idle state, and then initiates a non-SDT recovery process. Therefore, the SDT failure detection timer here is different from the window push timer in the technical terminology section above.

S303. The UE sends uplink SDT data to the second network device. Correspondingly, the second network device receives the uplink SDT data from the UE. The uplink SDT data includes data 1, 2, 3, and 4. Among them, 1, 2, 3, and 4 are the PDCPSNs of the uplink SDT data respectively.

For example, the uplink SDT data in S303 can be sent together with the RRC recovery request message 1 in S302. For example, the uplink SDT data is carried in the RRC recovery request message 1, and the uplink SDT data can be sent together with the RRC recovery request message 1 in S302. Can also be sent separately.

S304. The second network device sends an RLC status report to the UE. Correspondingly, the UE receives the RLC status report from the second network device, and the report indicates successful reception or unsuccessful reception of the uplink SDT data. For example, the second network device successfully receives the first SDT uplink data but fails to receive the second SDT uplink data. The report may indicate that the first SDT uplink data was successfully received (the SN of the first data is x, x is a natural number), but the second SDT uplink data was not successfully received (the SN of the second SDT uplink data is x+1). For another example, the report indicates that data 1, 3 were successfully received; data 2, 4 were not successfully received.

S305: The UE determines that SDT fails. For example, the UE performs cell reselection and reselects the cell of the first network device.

S306: The first network device sends the system information block 1 to the UE. Correspondingly, the UE receives the system information block 1 from the first network device. The system information block 1 carries the SDT configuration and the first indication information. The SDT configuration is used to indicate Time-frequency resources used for random access of SDT. The first indication information is used to indicate a mechanism to support data loss avoidance in the SDT process. The mechanism includes S307-S319. The first indication information here can also be carried in other messages and sent, and this application does not limit this. For example, the first indication information here may be expressed as support indication for avoidance of data loss.

The UE and the first network device restart the SDT failure detection timer.

It should be noted that if the system information block 1 does not carry the first indication information, or the system information block 1 carries another indication information, and the other indication information is used to indicate that avoiding data loss is not supported during the SDT process, then The UE will enter the idle state or continue cell reselection, that is to say, subsequent steps S307-S319 will not be executed.

S307: The UE sends the RRC recovery request 2 message to the first network device. Correspondingly, the first network device receives the RRC recovery request 2 message from the UE. The message includes the second resume MAC-I, the second resume MAC-I and The first resume MAC-I is different.

S308: The first network device sends an obtain context request message to the second network device. Correspondingly, the second network device receives the obtain context request message from the first network device.

S309: The second network device determines to perform anchor point relocation.

For example, the second network device may determine to perform anchor point relocation based on information such as its own load, or based on information received from the first network device.

S310: The second network device sends a retrieve UE context response message to the first network device. Correspondingly, the first network device receives the retrieve UE context response message from the second network device. The response message includes a hyper frame number (HFN) and PDCP SN. The PDCP SN here is used to determine the PDCP reception window. The HFN here is used to encrypt data transmitted between the network and the terminal device. The HFN and SN here may be the HFN and PDCP SN through which the network receives data from the terminal device. For example, the response message includes the HFN and PDCP SN of the second SDT uplink data.

Optionally, the message instructs the second network device to perform anchor relocation.

The first network device may determine the PDCP reception window based on the response information. Determining the PDCP receiving window can be understood as determining the range of the PDCP receiving window, that is, the starting SN and the ending SN of the PDCP receiving window. The starting SN of the receiving window is the PDCP SN included in the response message. The end SN of the receive window can be calculated in the following way: the sum of the starting SN and the length of the receive window is modulated by the length of the SN, and the remainder is the end SN. Optionally, if the response message includes multiple PDCP SNs, the first SN in the receiving order may be used as the SN of the PDCP receiving window. For example, the response message includes the PDCP SNs of the second SDT uplink data, which are 2 and 4. The starting SN of the PDCP receiving window is 2. Assume that the length of the receiving window is 4 bits, and the length of the SN is 8 bits, among which, the sum of the starting SN and the length of the receiving window is 6, and the modulus of 6 to 8 is 6, then the end SN is 6 of the current SN period.

In the above solution, when SDT fails, the second network device sends a status report to the first network device (anchor gNB). The first network device decides how to adjust the PDCP reception window based on the status, and the adjusted PDCP reception window. Therefore, the embodiment of the present application provides a solution for when the anchor gNB pushes the PDCP window.

S311. The first network device sends a path switch request message to the AMF. Correspondingly, the AMF receives the path switch request message from the first network device. The path switching request message is used to request the AMF to switch the connection between the UPF and the second network device to the connection between the UPF and the first network device. After path switching, the downlink data to be sent by the network to the UE is directly sent by the UPF to the first network device instead of being sent by the UPF to the second network device.

S312: The AMF sends a path switch acknowledge message to the first network device. Correspondingly, the first network device receives the path switch acknowledge message from the AMF.

S313, for details, please refer to S205 in method 200.

S314: The second network device uses the downlink forwarding tunnel address (received in S313) to forward (forwarding) the first SDT uplink data to the first network device. Correspondingly, the first network device receives the first forwarded data from the second network device. SDT uplink data. For example, the second network device sends a PDCP SDU to the first network device, and the PDCP SDU includes data 1 and 3.

It should be understood that when the second network device forwards the first SDT uplink data to the first network device, it may implicitly indicate that the first SDT uplink data is successfully received. Alternatively, the second network device may also explicitly indicate to the first network device that the first SDT uplink data is successfully received. For example, the second network device may send the content indicated in the status report sent to the UE in S304 to the first network. equipment.

In the above solution, the second network device forwards the successfully received uplink data to the first network device, which can save signaling overhead.

S315: The UE retransmits the second SDT uplink data to the first network device. Correspondingly, the first network device receives the second SDT uplink data from the UE. Since the SN of the second SDT uplink data (data 2, 4) is within the above-mentioned receiving window, the data is valid data. Then the first network device sorts the second SDT uplink data and the first SDT uplink data according to the PDCPSN.

The first network device delivers in-order delivery to the protocol layer above PDCP.

Because during the SDT process, when the UE undergoes cell reselection, the UE will enter the RRC idle state and will no longer transmit data packets, and packet loss is likely to occur. In this embodiment of the present application, after cell reselection, the packet loss rate can be reduced by using the UE to retransmit data that was not successfully received by the second network device.

S316: The first network device forwards the uplink SDT data (data 1, 2, 3, 4) to the AMF in order. Correspondingly, the AMF receives the uplink SDT data from the first network device.

S318: The first network device sends an RRC release message to the UE, and accordingly the UE receives the RRC release message from the first network device. The UE terminates the SDT process.

S319: The first network device sends a UE context release message to the second network device. Correspondingly, the second network device accepts the UE context release message from the first network device. The second network device releases the UE context and terminates communication with the UE.

Optionally, in S315, the UE may also send third uplink SDT data to the first network device, for example, data with PDCP SN numbers 5, 6, 7, and 8. Correspondingly, the first network device receives the third uplink SDT data from the UE. The key used when the UE sends data 1, 2, 3, and 4 to the second network device in S303 is different from the key used when the UE sends data 5, 6, 7, and 8 to the first network device in S315.

Figure 9 shows a schematic diagram of the data transmission method 400 provided by this application. In the following, the first network device is the receiving gNB (receiving gNB), the second network device is the last serving gNB (last serving gNB), the fourth downlink data is the second downlink SDT data (data 2 and 4), and the sixth downlink The data is data 5, 6, 7, and 8 as an example to introduce method 400. In method 400, after receiving downlink data from the second network device, the UE performs cell reselection and reselects the cell of the first network device. The UE initiates the SDT recovery process, and the first network device requests the context of the UE from the second network device. In the scenario where the second network device decides to perform anchor point relocation, it feeds back the RLC status to the first network device, so that the first network device adjusts the PDCP sending window according to the RLC status. The second network device retransmits the data that the UE failed to receive to the first network device, and the first network device sends the retransmitted data to the UE, so as to reduce the packet loss rate of downlink data. The protocol stack distribution of the UE, the first network device and the second network device can be seen in (b) in Figure 3 .

S401-S402, please refer to the description of S301-S302 for details.

S403: The second network device sends downlink SDT data to the UE, and accordingly, the UE receives the downlink SDT data from the second network device. The downlink SDT data includes data 1, 2, 3, and 4. Among them, 1, 2, 3, and 4 are the PDCPSNs of the downlink SDT data respectively.

S404: The UE sends an RLC status report to the second network device. Correspondingly, the second network device receives the RLC status report from the UE. For example, the UE successfully receives the first downlink SDT data but fails to receive the second downlink SDT data. The report may indicate that the first downlink SDT data was successfully received (for example, the SN of the first data is x, x is a natural number), and the second downlink SDT data was not successfully received (for example, the SN of the second downlink SDT data is x+1). For another example, the report indicates that data 1, 3 were successfully received; data 2, 4 were not successfully received.

S405-S409, please refer to the description of S305-S309 for details.

S410: The second network device sends a retrieve UE context response message to the first network device. Correspondingly, the first network device receives the retrieve UE context response message from the second network device.

For S411-S413, please refer to the description of S311-S313.

S414: The second network device forwards the second downlink SDT data to the first network device according to the downlink forwarding tunnel address provided in S413. Correspondingly, the first network device receives the second downlink SDT data from the second network device.

It should be understood that when the second network device forwards the second downlink SDT data to the first network device, it may implicitly indicate that the first downlink SDT data was unsuccessfully received. Alternatively, the second network device may also explicitly indicate to the first network device that the second downlink SDT data was unsuccessfully received. For example, the second network device sends an RLC status report to the first network device. The status report is used to indicate that the UE is successful. The first downlink SDT data is received, but the second downlink SDT data is not successfully received. The status report is determined based on the RLC status report received by the second network device from the UE in S404.

The first network device may determine the PDCP sending window according to the PDCP SN of the second downlink SDT data. The method of determining the PDCP sending window can refer to the description of determining the PDCP receiving window in S310. The difference is that the receiving window is replaced with the sending window, and the second uplink SDT data is replaced with the second downlink SDT data.

In the above solution, when SDT fails, the second network device sends a status report to the first network device (anchor gNB), and the first network device decides how to adjust the PDCP sending window based on the status. Therefore, the embodiment of this application is useful for the anchor point. The solution is given when gNB pushes the PDCP window.

S415: The first network device retransmits the second downlink SDT data to the UE. Correspondingly, the UE receives the second downlink SDT data from the first network device. Since the SN of the second downlink SDT data (data 2, 4) is within the above-mentioned transmission window, the data is valid data. Then the UE sorts the second downlink SDT data and the first downlink SDT data according to the PDCP SN.

The UE delivers in-order delivery to the protocol layer above PDCP.

Because during the SDT process, when the UE undergoes cell reselection, the UE will enter the RRC idle state and will no longer transmit data packets, and packet loss is likely to occur. In the embodiment of the present application, after cell reselection, the anchor point gNB (first network device) retransmits data that has not been successfully received by the UE, which can reduce the packet loss rate.

S416-S417, please refer to the description of S317-S318 for details.

Optionally, method 400 may also include:

In S410, the response message includes a PDCP SN that has not been allocated or used, for example, the SN=x+k, and k is an integer greater than 1. For example, 1, 2, 3, and 4 are PDCP SNs that have been allocated and used. The PDCP SN in the response message can be the next PDCP SN that has not been allocated or used, that is, 5.

In S415, the first network device may also send third downlink SDT data to the UE. The PDCP SN of the third downlink SDT data is after the first downlink SDT data and the second downlink SDT data, for example, data 5, 6, 7,8. The PDCP SN of the first data packet of the third downlink SDT data here is determined based on the PDCP SN that has not been allocated or used as indicated by the response message in S410.

The data transmission method 500 provided by this application will be introduced below with reference to Figures 10 and 11.

Figure 10 shows a schematic flow chart of the data transmission method 500 provided by this application. The second network device is the last serving gNB, the first network device is the receiving gNB, and the third network device is the last receiving gNB (last receiving gNB). As shown in Figure 10, the UE is not within the coverage of the second network device, the UE initiates the SDT recovery process to the third network device, the third network device requests the context of the UE from the second network device, and the second network device decides not to execute the anchor. Point redirection, the UE and the second network device communicate through the third network device. The first network device sends data 1, 2, 3, 4 to the third network device, and the third network device sends data 1, 2, 3, 4 to the UE. The UE feeds back a first RLC status report to the third network device. The RLC status report indicates that the UE successfully received data 1 and 3 but failed to receive data 2 and 4. Subsequently, the UE performs cell reselection to the cell where the first network device is located, and initiates an SDT recovery process to the first network device, and the first network device requests the context of the UE from the second network device. In the scenario where the second network device decides not to perform anchor point relocation, the second network device obtains the RLC status report of the UE through the third network device and feeds back to the first network device whether the UE successfully or unsuccessfully receives data, so that The first network device pushes the PDCP send window. The second network device forwards data 2, 4 to the first network device, and the second network device retransmits data 2, 4 to the UE, which can reduce the packet loss rate of downlink data. Before the UE performs cell reselection, the protocol stack distribution of the UE, the third network device and the second network device can be seen in (a) in Figure 3. After the UE performs cell reselection, the protocol stack distribution of the UE, the first network device and the second network device The protocol stack distribution of network equipment can also be seen in (a) in Figure 3.

Figure 11 shows a schematic block diagram of a data transmission method 500 provided by this application. The method 500 will be introduced below by taking the first network device as the fifth downlink data as data 1 and 3, the fourth downlink data as data 2 and 4, and the sixth downlink data as data 5, 6, 7, and 8.

For S501-S502, please refer to the description of S401-S402 for details. The difference is that: the RRC release message in S401 is replaced with the first RRC release message; the second network device in S402 is replaced with the third network device.

S503-S505, please refer to the description of S202-S204 for details. The difference is: replace the first network device in S202-S204 with the third network device, and replace the "get context request message" in S202-S204 with "get context" Request message 1", replace "SDT context" in S202-S204 with "SDT context 1".

S506: The second network device sends downlink SDT data to the UE through the third network device. The second network device sends downlink SDT data to the third network device, and accordingly, the third network device receives the downlink SDT data from the second network device. The third network device sends downlink SDT data to the UE, and accordingly, the UE receives the downlink SDT data from the third network device. The downlink SDT data includes data 1, 2, 3, and 4. Among them, 1, 2, 3, and 4 are the PDCP SNs of the downlink SDT data respectively.

For S507, please refer to the description of S404. The difference is that the second network device in S404 is replaced with a third network device.

S508-S509, please refer to the corresponding descriptions of S405-S406.

For S510-S511, please refer to the description of S202-S203.

It should be understood that the second network device does not perform anchor point relocation here, so the PDCP protocol layer is still on the second network device. The PDCP layer includes the context of the UE. Therefore, the first network device sends to the second network device in S510 to obtain the UE. Context Request 2.

S512. The second network device sends an RLC status report request message to the third network device. Correspondingly, the third network device receives the RLC status report request message from the first network device. This message is used to request the UE's RLC status report.

S513. The third network device sends a second RLC status report to the second network device. Correspondingly, the second network device receives the second RLC status report from the third network device. The status report needs to indicate the logical channel number of the SDT data. Or RB index, and PDCP SN or RLC SN.

For example, the UE successfully receives the first downlink SDT data but fails to receive the second downlink SDT data. The report may indicate successful reception of the first downlink SDT data and unsuccessful reception of the second downlink SDT data. And carry the logical channel number of the first downlink SDT data and the second downlink SDT data or the RB index that carries the first downlink SDT data and the second downlink SDT data, as well as the first downlink SDT data and the second downlink SDT data. PDCP SN or RLC SN.

It should be understood that, after receiving the obtain UE context request 2 from the first network device in S510, the second network device learns that the UE is reselected to the cell of the first network device. The second network device obtains the RLC status of the UE through S512 and S513, adjusts the PDCP sending window according to the UE's RLC status report, and retransmits the downlink data that the UE failed to receive to the UE through the first network device in subsequent steps.

The way in which the second network device adjusts the transmission window of PDCP may refer to the way in which the first network device adjusts the transmission window of PDCP in step S414 of method 400.

In the above solution, the UE transmits data to the second network device through the third network device and the first network device successively, and the second network device as the anchor point gNB negotiates the status report between the third network device and the first network device, that is, The status report is obtained from the third network device, and the first network device determines how to adjust the PDCP sending window based on the RLC status provided by the third network device. Therefore, the embodiment of this application provides a solution for when the anchor gNB pushes the PDCP window.

S514. The third network device releases the connection with the UE and stops communicating with the UE.

S514 may also be performed after S512 and before S513, or may be performed at any step after S513, which is not limited by this application.

S515: The second network device sends a retrieve UE context response message to the first network device. Correspondingly, the first network device receives the retrieve UE context response message from the second network device. This message can carry the configuration of PDCP and the transmission window information of PDCP (such as the next PDCPSN to be sent) and the status report of PDCP. The status report of PDCP is used to indicate that the data has been successfully received by the terminal device.

Optionally, the message indicates that the second network device does not perform anchor relocation.

S516, please refer to the description of S413 for details.

S517: The second network device forwards the downlink data to the first network device according to the downlink forwarding tunnel address provided in S516. Correspondingly, the first network device receives the downlink data from the second network device, that is, the above-mentioned second downlink SDT data.

It should be understood that when the second network device forwards the second downlink SDT data to the first network device, it may implicitly indicate that the first downlink SDT data was unsuccessfully received. Alternatively, the second network device may also explicitly indicate to the first network device that the second downlink SDT data was unsuccessfully received. For example, the second network device sends an RLC status report to the first network device. The status report is used to indicate that the UE is successful. The first downlink SDT data is received, but the second downlink SDT data is not successfully received. The status report is determined based on the second RLC status report received by the second network device from the third network device in S513.

Because during the SDT process, when the UE undergoes cell reselection, the UE will enter the RRC idle state and will no longer transmit data packets, and packet loss is likely to occur. In this embodiment of the present application, after cell reselection, the packet loss rate can be reduced by using the UE to retransmit data that was not successfully received by the second network device.

S518: The first network device retransmits the second downlink SDT data to the UE. Correspondingly, the UE receives the second downlink SDT data from the first network device. Since the SN of the second downlink SDT data (data 2, 4) is within the above-mentioned transmission window, the data is valid data. Then the UE sorts the second downlink SDT data and the first downlink SDT data according to the PDCP SN.

The UE delivers in-order delivery to the protocol layer above PDCP.

S519: The first network device sends the second RRC release message to the UE through the third network device. The first network device sends a second RRC release message to the third network device, and accordingly, the third network device receives the second RRC release message from the first network device. The third network device sends the second RRC release message to the UE, and accordingly, the UE receives the second RRC release message from the third network device.

After receiving this message, the terminal device terminates the SDT process.

Optionally, in S518, the first network device may also send third downlink SDT data to the UE, the PDCP SN of the third downlink SDT data is after the first downlink SDT data and the second downlink SDT data, for example, data 5, 6, 7, 8. The PDCP SN of the first data packet of the third downlink SDT data here is determined based on the PDCP sending window information in S515.

The following describes the data transmission method 600 provided by this application.

Method 600 can be combined with any one of methods 100 to 120 and methods 200 to 500. In methods 300 to 500, the UE has already performed cell reselection. Then in method 600, the UE can count the number of cell reselections during the SDT process. In method 200, the UE does not perform cell reselection. If the UE performs cell reselection in the subsequent SDT process, the number of cell reselections can also be counted according to method 600. When the number of cell reselections counted by the UE during the SDT process is greater than or equal to a preset value Y, Y is a positive integer, the UE enters the idle state, or initiates a non-SDT recovery process. Among them, the UE performs a cell reselection, which can be understood as an SDT failure.

S601. The UE obtains the default value Y.

The preset value Y may be sent by the network device to the UE through an RRC release message. Correspondingly, the UE receives the RRC release message from the w network device, which indicates the maximum number of cell reselections Y in the SDT process.

The network device here may be the anchor network device in the aforementioned method.

S602: After receiving the RRC release message, the UE enters the inactive state and saves the access stratum (AS) context.

S603. The UE initiates an SDT process. During this process, due to mobility, the terminal device may perform cell reselection one or more times, and the UE records the number of cell reselections.

S604: When the number of cell reselections reaches Y, the UE stops cell reselection, or the UE directly switches to the idle state and releases all AS contexts, or the UE initiates a non-SDT recovery process.

In the embodiment of this application, a threshold is set for the number of cell reselections for the UE, and the UE counts the number of cell reselections. When the number of cell reselections reaches the threshold, the cell reselection is stopped or switched to the idle state or a non-SDT recovery process is initiated. , Reduce the reduction of communication efficiency caused by continuous SDT failure, and improve communication efficiency.

FIG. 12 is a schematic diagram of a data transmission device 600 provided by an embodiment of the present application. The device 600 includes a transceiver unit 610, which can be used to implement corresponding communication functions. The transceiver unit 610 may also be called a communication interface or a communication unit.

Optionally, the device 600 may also include a processing unit 620, which may be used for data processing.

Optionally, the device 600 also includes a storage unit, which can be used to store instructions and/or data, and the processing unit 620 can read the instructions and/or data in the storage unit, so that the device implements each of the foregoing method embodiments. Actions performed by communication equipment (such as terminal equipment and network equipment).

The device 600 can be used to perform the actions performed by the communication device (such as a terminal device, or a network device) in each of the above method embodiments. In this case, the device 600 can be a communication device (such as a terminal device, or a network device). ), the transceiver unit 610 is used to perform transceiver-related operations on the side of the communication device (such as a terminal device, or a network device) in the above method embodiment, and the processing unit 620 is used to perform the communication device in the above method embodiment. Processing-related operations on the side (such as terminal equipment or network equipment).

As a design, the device 600 is used to perform the actions performed by the terminal device in each of the above method embodiments.

In one possible implementation, the transceiver unit 610 is configured to receive second instruction information from the second network device. The second instruction information is used to instruct to avoid data loss during the transmission of small data packets; and is also configured to receive the fourth downlink data, the fourth downlink data is small data; also used to send indication information indicating that the fourth downlink data has not been successfully received; and also used to receive first indication information from the first network device, the first indication information It is used to instruct the first network device to support avoiding data loss during the transmission of small data packets; and it is also used to receive the fourth downlink data from the first network device.

Optionally, the transceiver unit 610 is specifically configured to receive the fourth downlink data from the second network device; the transceiver unit 610 is specifically configured to send a first status report to the second network device, where the first status report includes This instruction message.

Optionally, the transceiver unit 610 is specifically configured to receive the fourth downlink data from the third network device; the transceiver unit 610 is specifically configured to send a second status report to the third network device, where the second status report includes the Instructions.

Optionally, the transceiver unit 610 is also configured to receive a radio resource control release message from the network device. The radio resource control release message includes Y, where Y is the number of cell reselections during small data packet transmission, and Y is a positive integer. ; The processing unit 620 is used to initiate the small data packet transmission process; the terminal equipment records the number of cell reselections; when the number of cell reselections recorded by the device is ≥ Y, the processing unit 620 is also used to switch to wireless The resource control idle state, or the transceiver unit 610, is also used to send a recovery request message for non-small data packet transmission to the network device.

In another possible implementation, the transceiver unit 610 is used to receive the second instruction information from the second network device. The second instruction information is used to instruct to avoid data loss during the transmission of small data packets; the transceiver unit 610 is also used to The transceiver unit 610 is also configured to receive a third status report from the second network device, and the third status report includes the following instructions. At least one of the information: indication information indicating successful reception of the first uplink data, indication information indicating unsuccessful reception of the second uplink data, wherein the fourth uplink data includes the first uplink data and the third uplink data. 2. Uplink data; the transceiver unit 610 is also used to receive the first indication information from the first network device, the first indication information is used to instruct the first network device to support avoiding data loss during the transmission of small data packets; the transceiver unit 610: Also used to send the second uplink data to the first network device.

It should be understood that the specific process of each unit performing the above corresponding steps has been described in detail in each of the above method embodiments, and will not be described again for the sake of brevity.

As another design, the device 600 is configured to perform the actions performed by the first network device in each of the above method embodiments.

In one possible implementation, the transceiver unit 610 is used to receive the first downlink data from the second network device, where the first downlink data is small data; and is also used to send the first downlink data to the terminal device; It is also used to receive a first feedback message from the terminal device, the first feedback message is used to indicate successful or unsuccessful reception of the first downlink data, and the feedback message corresponds to the first protocol layer; A feedback message sends a second feedback message to the second network device. The first feedback message is used to indicate that the first downlink data is successfully received. The second feedback message is used to indicate that the terminal device successfully receives the first downlink data. For downlink data, the second feedback message corresponds to the second protocol layer.

Exemplarily, the first feedback message includes at least one of the following: the sequence number of the first downlink data in the first protocol layer, the identification of the radio bearer carrying the first downlink data, the The identification of the logical channel of the data, the second feedback message includes at least one of the following: the sequence number of the first downlink data in the second protocol layer, the sequence number of the first downlink data in the first protocol layer, The identifier of the radio bearer that carries the first downlink data and the identifier of the logical channel that carries the first downlink data.

Optionally, the processing unit 620 is configured to start a timer according to the first feedback message.

Optionally, when the timer times out, the transceiving unit 610 is further configured to send a second feedback message to the second network device according to the first feedback message.

Optionally, the processing unit 620 is specifically configured to determine according to the first feedback message that the terminal device successfully receives M pieces of data of the first protocol layer, where M is a positive integer; when among the M pieces of data, the sequence number of the second protocol layer When the number of consecutive data is greater than or equal to N, the transceiver unit 610 is specifically configured to send a second feedback message to the second network device. The second feedback message is used to indicate that the terminal device successfully received the second protocol layer. N data includes the first downlink data, and N is a positive integer.

For example, the first protocol layer is a radio link control layer, and the second protocol layer is a packet data convergence layer.

Optionally, the transceiver unit 610 is also configured to send a first request message to the second network device. The first request message is used to request to obtain the context of the terminal device. The first request message includes a message indicating a small data packet. The transmitted instruction information; the transceiver unit 610 is also configured to receive a first response message from the second network device, where the first response message includes instruction information indicating not to perform anchor point relocation.

Optionally, the transceiver unit 610 is also configured to send first indication information to the terminal device, where the first indication information is used to instruct the first network device to support avoiding data loss during small data packet transmission; the transceiver unit 610, It is also used to receive the fourth downlink data from the second network device. The fourth downlink data is unsuccessfully received by the terminal device. The fourth downlink data is small data. The transceiver unit 610 is also used to send data to the terminal device. Send the fourth downlink data.

Optionally, the transceiver unit 610 is also configured to send a second request message to the second network device. The second request message is used to request to obtain the context of the terminal device. The second request message includes a small data packet indicating The transmitted instruction information; the transceiver unit 610 is also configured to receive a second response message from the second network device, where the second response message includes instruction information for instructing to perform anchor point relocation.

Optionally, the transceiver unit 610 is also configured to send a third request message to the second network device. The third request message is used to request to obtain the context of the terminal device. The third request message includes a message indicating a small data packet. The transmitted instruction information; the transceiver unit 610 is also configured to receive a third response message from the second network device, where the third response message includes instruction information indicating not to perform anchor point relocation.

Optionally, the transceiver unit 610 is also configured to send a radio resource control release message to the terminal device. The radio resource control release message includes Y, where Y is the number of cell reselections during small data packet transmission, and Y is a positive integer.

In another possible implementation, the transceiver unit 610 is configured to send first indication information to the terminal device, where the first indication information is used to instruct the first network device to support avoiding data loss during small data packet transmission; the third A network device receives first uplink data from a second network device. The first uplink data is data successfully received by the second network device. The first uplink data is small data. The transceiver unit 610 is also used to receive data from the second network device. The second uplink data of the terminal device, the second uplink data is the data from the terminal device that was not successfully received by the second network device, and the second uplink data is small data.

Optionally, the transceiver unit 610 is also configured to send a second request message to the second network device. The second request message is used to request to obtain the context of the terminal device. The second request message includes a small data packet indicating The transmission instruction information; the transceiver unit 610 is also configured to receive a second response message from the second network device, where the second response message is used to instruct the second network device to decide to perform anchor point relocation.

It should be understood that the specific process of each unit performing the above corresponding steps has been described in detail in each of the above method embodiments, and will not be described again for the sake of brevity.

As another design, the device 600 is configured to perform the actions performed by the second network device in each of the above method embodiments.

In one possible implementation, the transceiver unit 610 is configured to send the first downlink data to the first network device, where the first downlink data is small data, and the first network device is configured to send the first downlink data. To the terminal device; the transceiver unit 610 is also used to receive a second feedback message from the first network device. The second feedback message is used to indicate whether the terminal device has successfully received or failed to receive the first downlink data. The feedback message corresponds to the second protocol layer; the processing unit 620 is configured to determine the second sending window according to the first sending window and the second feedback message. The first sending window contains the sequence number of the first downlink data. In the If the second feedback message indicates that the first downlink data is successfully received, the second sending window includes the sequence number of the downlink data that has not been sent to the terminal device.

Exemplarily, the sequence number of the first downlink data in the second protocol layer, the superframe number of the first downlink data in the second protocol layer, the identification of the radio bearer carrying the first downlink data, The identifier of the logical channel carrying the first downlink data.

Optionally, the processing unit 620 is specifically configured for the second network device to determine according to the second feedback message that the data corresponding to the first L sequence numbers of the first sending window have been successfully received by the terminal device. The second sending window The starting sequence number is equal to the sequence number corresponding to the L+1th data of the first sending window, and L is a positive integer.

Optionally, the second feedback message is used to indicate that the terminal device successfully receives N pieces of data with consecutive sequence numbers of the second protocol layer. The N pieces of data include the first downlink data. N is a positive integer, L= N.

Illustratively, the second protocol layer is a packet data convergence layer.

Optionally, the transceiver unit 610 is also configured to receive a first request message from the first network device. The first request message is used to request to obtain the context of the terminal device. The first request message includes a message indicating small data. Instruction information for packet transmission; the transceiver unit 610 is also configured to send a first response message to the first network device, where the first response message includes instruction information indicating not to perform anchor point relocation.

Optionally, the transceiver unit 610 is also configured to send second instruction information to the terminal device, where the second instruction information is used to instruct to avoid data loss during the transmission of small data packets; the transceiver unit 610 is also configured to send the fourth downlink data, the fourth downlink data is small data; the transceiver unit 610 is also used to receive a first status report, the first status report includes indication information indicating that the terminal device has not successfully received the fourth downlink data; the transceiver unit 610 610. Also used to send the fourth downlink data to the first network device.

Optionally, the transceiver unit 610 is specifically configured to send the fourth downlink data to the terminal device; the transceiver unit 610 is specifically configured to receive the first status report from the terminal device.

Optionally, the transceiver unit 610 is also configured to receive a second request message from the first network device. The second request message is used to request to obtain the context of the terminal device. The second request message includes a message indicating small data. Instruction information for packet transmission; the transceiver unit 610 is also configured to send a second response message to the second network device, where the second response message includes instruction information for instructing to perform anchor point relocation.

Optionally, the transceiver unit 610 is specifically configured to send the fourth downlink data to the third network device; the transceiver unit 610 is specifically configured to receive the first status report from the third network device.

Optionally, the transceiver unit 610 is also configured to send a fourth request message to the third network device, where the fourth request message is used to request a status report of the fourth downlink data.

Optionally, the transceiver unit 610 is also configured to receive a third request message from the first network device. The third request message is used to request to obtain the context of the terminal device. The third request message includes a message indicating small data. Instruction information for packet transmission; the transceiver unit 610 is also configured to send a third response message to the first network device, where the third response message includes instruction information indicating not to perform anchor point relocation.

Optionally, the method also includes: a transceiver unit 610, which is also configured to send a radio resource control release message to the terminal device, where the radio resource control release message includes Y, where Y is the number of cell reselections during small data packet transmission, Y is a positive integer.

In another possible implementation, the transceiver unit 610 is used to send second instruction information to the terminal device. The second instruction information is used to instruct to avoid data loss during the transmission of small data packets; the transceiver unit 610 is also used to receive data from The fourth uplink data of the terminal device, the fourth uplink data is small data; the transceiver unit 610 is also used to send a third status report to the terminal device, the third status report includes at least one of the following indication information: Instruction information used to indicate successful reception of the first uplink data, indication information used to indicate unsuccessful reception of the second uplink data, the fourth uplink data includes the first uplink data and the second uplink data; the transceiver unit 610 also Used to send the first uplink data to the first network device.

Optionally, the transceiver unit 610 is also configured to receive a second request message from the second network device. The second request message is used to request to obtain the context of the terminal device. The second request message includes a message indicating small data. Instruction information for packet transmission; the transceiver unit 610 is also configured to send a second response message to the second network device, where the second response message is used to instruct the second network device to decide to perform anchor point relocation.

It should be understood that the specific process of each unit performing the above corresponding steps has been described in detail in each of the above method embodiments, and will not be described again for the sake of brevity.

It should also be understood that the device 600 here is embodied in the form of a functional unit. The term "unit" as used herein may refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor for executing one or more software or firmware programs (e.g., a shared processor, a dedicated processor, or a group of processors). processor, etc.) and memory, merged logic circuitry, and/or other suitable components to support the described functionality. In an optional example, those skilled in the art can understand that the apparatus 600 can be specifically a terminal device in the above embodiments, and can be used to execute various processes and/or steps corresponding to the terminal device in the above method embodiments, or , the apparatus 600 may be specifically the first network device or the second network device in the above embodiments, and may be used to execute various processes and/or steps corresponding to the first network device or the second network device in the above method embodiments, To avoid repetition, they will not be repeated here.

The device 600 of each of the above solutions has the function of realizing the corresponding steps performed by the terminal device in the above method, or the device 600 of each of the above solutions has the function of realizing the corresponding steps of the first network device or the second network device of the above method. . The functions described can be implemented by hardware, or can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions; for example, the transceiver unit can be replaced by a transceiver (for example, the sending unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiving unit. (machine replacement), other units, such as processing units, etc., can be replaced by processors to respectively perform the sending and receiving operations and related processing operations in each method embodiment.

In addition, the above-mentioned transceiver unit 610 may also be a transceiver circuit (for example, it may include a receiving circuit and a transmitting circuit), and the processing unit may be a processing circuit.

It should be noted that the device in Figure 12 may be a network element or device in the aforementioned embodiment, or may be a chip or chip system, such as a system on chip (SoC). The transceiver unit may be an input-output circuit or a communication interface; the processing unit may be a processor, microprocessor, or integrated circuit integrated on the chip. No limitation is made here.

FIG. 13 is a schematic diagram of another data transmission device 700 provided by an embodiment of the present application. The device 700 includes a processor 710 coupled to a memory 720 for storing computer programs or instructions and/or data. The processor 710 is used for executing computer programs or instructions stored in the memory 720, or reading the memory 720. The stored data is used to execute the methods in the above method embodiments.

Optionally, there are one or more processors 710 .

Optionally, there are one or more memories 720 .

Optionally, the memory 720 is integrated with the processor 710, or is provided separately.

Optionally, as shown in Figure 13, the device 700 also includes a transceiver 1030, which is used for receiving and/or transmitting signals. For example, the processor 710 is used to control the transceiver 1030 to receive and/or transmit signals.

As a solution, the device 700 is used to implement the operations performed by the terminal device in each of the above method embodiments.

For example, the processor 710 is used to execute computer programs or instructions stored in the memory 720 to implement related operations of the terminal device in each of the above method embodiments. For example, the method executed by the terminal device in the embodiment shown in Figure 5 or Figure 6.

As a solution, the apparatus 700 is used to implement the operations performed by the first network device or the second network device in each of the above method embodiments.

For example, the processor 710 is used to execute computer programs or instructions stored in the memory 720 to implement related operations of the network device in each of the above method embodiments. For example, the method performed by the network device in the embodiment shown in Figure 5 or Figure 6.

It should be understood that the processor mentioned in the embodiments of this application may be a central processing unit (CPU), or other general-purpose processor, digital signal processor (DSP), application specific integrated circuit (Application Specific Integrated Circuit). integrated circuit (ASIC), ready-made field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory and/or a non-volatile memory. Among them, the non-volatile memory can be read-only memory (ROM), programmable ROM (PROM), erasable programmable read-only memory (erasable PROM, EPROM), electrically removable memory. Erase programmable read-only memory (electrically EPROM, EEPROM) or flash memory. Volatile memory may be random access memory (RAM). For example, RAM can be used as an external cache. By way of example and not limitation, RAM includes the following forms: static random access memory (static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous dynamic random access memory (synchronous DRAM, SDRAM), Double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), synchronous link dynamic random access memory (synchlinkDRAM, SLDRAM) and direct memory Bus random access memory (direct rambus RAM, DR RAM).

It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory (storage module) can be integrated in the processor.

It should also be noted that the memories described herein are intended to include, but are not limited to, these and any other suitable types of memories.

Figure 14 is a schematic diagram of a chip system 800 provided by an embodiment of the present application. The chip system 800 (or may also be referred to as a processing system) includes a logic circuit 810 and an input/output interface (input/output interface) 820.

The logic circuit 810 may be a processing circuit in the chip system 800 . The logic circuit 810 can be coupled to the storage unit and call instructions in the storage unit, so that the chip system 800 can implement the methods and functions of various embodiments of the present application. The input/output interface 820 can be an input/output circuit in the chip system 800, which outputs information processed by the chip system 800, or inputs data or signaling information to be processed into the chip system 800 for processing.

Specifically, for example, if the terminal device is installed with the chip system 800, the logic circuit 810 is coupled with the input/output interface 820, the logic circuit 810 can discover a message to the network device through the input/output interface 820, and the message can be a message that the logic circuit 810 can send according to the input/output interface 820. generated; or the input/output interface 820 may input the first information from the network device to the logic circuit 810 for processing. For another example, if the network device is installed with the chip system 800, the logic circuit 810 is coupled with the input/output interface 820, the logic circuit 810 can send the first information to the terminal device through the input/output interface 820, and the first information can be the logic circuit 810; or the input/output interface 820 can input messages from the terminal device to the logic circuit 810 for processing.

As a solution, the chip system 800 is used to implement the operations performed by the terminal device in each of the above method embodiments.

For example, the logic circuit 810 is used to implement the processing-related operations performed by the terminal device in the above method embodiment, such as the processing-related operations performed by the terminal device in the embodiment shown in FIG. 2 or FIG. 3 or FIG. 4; input The /output interface 820 is used to implement the sending and/or receiving related operations performed by the terminal device in the above method embodiment, such as the sending and/or receiving operations performed by the terminal device in the embodiment shown in Figure 2 or Figure 3 or Figure 4. or receive related operations.

As another solution, the chip system 800 is used to implement the operations performed by the network device in each of the above method embodiments.

For example, the logic circuit 810 is used to implement processing-related operations performed by the network device in the above method embodiment, such as processing-related operations performed by the network device in the embodiment shown in FIG. 2 or FIG. 3 or FIG. 4; input The /output interface 820 is used to implement the sending and/or receiving related operations performed by the network device in the above method embodiment, such as the sending and/or receiving operations performed by the network device in the embodiment shown in Figure 2 or Figure 3 or Figure 4. or receive related operations.

Embodiments of the present application also provide a computer-readable storage medium on which are stored computer instructions for implementing the methods executed by terminal devices or network devices in each of the above method embodiments.

For example, when the computer program is executed by a computer, the computer can implement the method executed by the terminal device or network device in each embodiment of the above method.

Embodiments of the present application also provide a computer program product, which includes instructions. When the instructions are executed by a computer, the methods executed by terminal devices or network devices in each of the above method embodiments are implemented.

An embodiment of the present application also provides a communication system, which includes the terminal equipment and network equipment in the above embodiments. For example, the system includes the terminal device and the network device in the embodiment shown in Figure 2 or Figure 3 or Figure 4 .

For explanations of relevant content and beneficial effects of any of the devices provided above, please refer to the corresponding method embodiments provided above, and will not be described again here.

In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or can be integrated into another system, or some features can be ignored, or not implemented. In addition, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the devices or units may be in electrical, mechanical or other forms.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it may 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. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. For example, the computer may be a personal computer, a server, or a network device. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another, e.g., the computer instructions may be transferred from a website, computer, server, or data center Transmission to another website, computer, server or data center by wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that contains one or more available media integrated. The available media may be magnetic media (such as floppy disks, hard disks, magnetic tapes), optical media (such as DVDs), or semiconductor media (such as solid state disks (SSD)). For example, the aforementioned available media include but Not limited to: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk and other media that can store program code.

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (36)

1. A method of data transmission, comprising:

the method comprises the steps that first network equipment receives first downlink data from second network equipment, wherein the first downlink data are small data;

the first network device sends the first downlink data to a terminal device;

the first network device receives a first feedback message from the terminal device, where the first feedback message is used to indicate successful or unsuccessful reception of the first downlink data, and the feedback message corresponds to a first protocol layer;

the first network device sends a second feedback message to the second network device according to the first feedback message, wherein the first feedback message is used for indicating that the terminal device successfully receives the first downlink data when the first feedback message is used for indicating that the first downlink data is successfully received, and the second feedback message corresponds to a second protocol layer.

2. The method of claim 1, wherein the first feedback message comprises at least one of: the first downlink data is at the sequence number of the first protocol layer, the identifier of the radio bearer carrying the first downlink data, and the identifier of the logic channel carrying the first downlink data, and the second feedback message includes at least one of the following: the sequence number of the first downlink data in the second protocol layer, the sequence number of the first downlink data in the first protocol layer, the identification of the radio bearer carrying the first downlink data, and the identification of the logical channel carrying the first downlink data.

3. The method according to claim 1 or 2, characterized in that the method further comprises:

the first network device starts a timer according to the first feedback message.

4. A method according to claim 3, wherein the first network device sending a second feedback message to the second network device according to the first feedback message, comprising:

and under the condition that the timer is overtime, the first network equipment sends a second feedback message to the second network equipment according to the first feedback message.

5. The method according to any of claims 1 to 4, wherein the first network device sending a second feedback message to the second network device according to the first feedback message, comprising:

the first network device determines that the terminal device successfully receives M data of the first protocol layer according to the first feedback message, wherein M is a positive integer;

and when the number of the data with continuous serial numbers of the second protocol layer in the M data is greater than or equal to N, the first network equipment sends a second feedback message to the second network equipment, wherein the second feedback message is used for indicating the terminal equipment to successfully receive the N data of the second protocol layer, the N data comprise the first downlink data, and the N is a positive integer.

6. The method according to any one of claims 1 to 5, wherein the first protocol layer is a radio link control layer and the second protocol layer is a packet data convergence layer.

7. The method according to any one of claims 1 to 6, further comprising:

the first network device sends a first request message to the second network device, wherein the first request message is used for requesting to acquire the context of the terminal device, and the first request message comprises indication information for indicating small data packet transmission;

The first network device receives a first response message from the second network device, the first response message including indication information indicating that anchor relocation is not performed.

8. The method according to any one of claims 1 to 7, further comprising:

the first network device sends first indication information to the terminal device, wherein the first indication information is used for indicating the first network device to support avoiding data loss in the small data packet transmission process;

the first network device receives fourth downlink data from the second network device, wherein the fourth downlink data is data which is not successfully received by the terminal device, and the fourth downlink data is small data;

and the first network equipment sends the fourth downlink data to the terminal equipment.

9. The method of claim 8, wherein the method further comprises:

the first network device sends a second request message to the second network device, wherein the second request message is used for requesting to acquire the context of the terminal device, and the second request message comprises indication information for indicating small data packet transmission;

The first network device receives a second response message from the second network device, the second response message including indication information indicating that anchor relocation is performed.

10. The method of claim 8, wherein the method further comprises:

the first network device sends a third request message to the second network device, wherein the third request message is used for requesting to acquire the context of the terminal device, and the third request message comprises indication information for indicating small data packet transmission;

the first network device receives a third response message from the second network device, the third response message including indication information indicating that anchor relocation is not performed.

11. The method according to any one of claims 1 to 10, further comprising:

and the first network equipment sends a radio resource control release message to the terminal equipment, wherein the radio resource control release message comprises Y, Y is the number of cell reselection in the transmission process of the small data packet, and Y is a positive integer.

12. A method of data transmission, comprising:

the second network equipment sends first downlink data to the first network equipment, wherein the first downlink data are small data, and the first network equipment is used for sending the first downlink data to the terminal equipment;

The second network device receives a second feedback message from the first network device, where the second feedback message is used to indicate that the terminal device successfully receives or does not successfully receive the first downlink data, and the second feedback message corresponds to a second protocol layer;

the second network device determines a second sending window according to a first sending window and the second feedback message, wherein the first sending window comprises the sequence number of the first downlink data, and the second sending window comprises the sequence number of the downlink data which is not sent to the terminal device under the condition that the second feedback message indicates that the first downlink data is successfully received.

13. The method of claim 12, wherein the second feedback message comprises at least one of: the sequence number of the first downlink data in the second protocol layer, the super frame number of the first downlink data in the second protocol layer, the identification of the radio bearer carrying the first downlink data, and the identification of the logical channel carrying the first downlink data.

14. The method according to claim 12 or 13, characterized in that the method further comprises:

And the second network device determines that the data corresponding to the first L serial numbers of the first sending window are successfully received by the terminal device according to the second feedback message, the initial serial number of the second sending window is equal to the serial number corresponding to the (L+1) th data of the first sending window, and L is a positive integer.

15. The method according to claim 12 or 13, wherein the second feedback message is used to indicate that the terminal device successfully receives N consecutive data of the sequence number of the second protocol layer, where N is a positive integer, and l=n, and the N data includes the first downlink data.

16. The method according to any of claims 12 to 14, wherein the second protocol layer is a packet data convergence layer.

17. The method according to any one of claims 12 to 16, further comprising:

the second network device receives a first request message from the first network device, wherein the first request message is used for requesting to acquire the context of the terminal device, and the first request message comprises indication information for indicating small data packet transmission;

the second network device sends a first response message to the first network device, the first response message including indication information indicating that anchor relocation is not performed.

18. The method according to any one of claims 12 to 17, comprising:

the second network device sends second indication information to the terminal device, wherein the second indication information is used for indicating that data loss is avoided in the transmission process of the small data packet;

the second network device sends fourth downlink data, wherein the fourth downlink data is small data;

the second network device receives a first status report, wherein the first status report comprises indication information for indicating that the terminal device does not successfully receive the fourth downlink data;

and the second network equipment sends the fourth downlink data to the first network equipment.

19. The method of claim 18, wherein the step of providing the first information comprises,

the second network device sending fourth downlink data, including: the second network device sends the fourth downlink data to the terminal device;

the second network device receives a first status report, comprising: the second network device receives the first status report from the terminal device.

20. The method of claim 19, wherein the method further comprises:

the second network device receives a second request message from the first network device, wherein the second request message is used for requesting to acquire the context of the terminal device, and the second request message comprises indication information for indicating small data packet transmission;

The second network device sends a second response message to the second network device, the second response message including indication information for indicating to perform anchor relocation.

21. The method of claim 18, wherein the step of providing the first information comprises,

the second network device sending fourth downlink data, including: the second network device sends the fourth downlink data to a third network device;

the second network device receives a first status report, comprising: the second network device receives the first status report from the third network device.

22. The method of claim 21, wherein the method further comprises: the second network device sends a fourth request message to the third network device, where the fourth request message is used to request a status report of the fourth downlink data.

23. The method according to claim 21 or 22, characterized in that the method further comprises:

the second network device receives a third request message from the first network device, wherein the third request message is used for requesting to acquire the context of the terminal device, and the third request message comprises indication information for indicating small data packet transmission;

The second network device sends a third response message to the first network device, the third response message including indication information indicating that anchor relocation is not performed.

24. The method according to any one of claims 12 to 23, further comprising:

and the first network equipment sends a radio resource control release message to the terminal equipment, wherein the radio resource control release message comprises Y, Y is the number of cell reselection in the transmission process of the small data packet, and Y is a positive integer.

25. A method of data transmission, comprising:

the terminal equipment receives second indication information from second network equipment, wherein the second indication information is used for indicating that data loss is avoided in the transmission process of the small data packet;

the terminal equipment receives fourth downlink data, wherein the fourth downlink data is small data;

the terminal equipment sends indication information for indicating that the fourth downlink data is not successfully received;

the terminal equipment receives first indication information from first network equipment, wherein the first indication information is used for indicating the first network equipment to support avoiding data loss in the small data packet transmission process;

The terminal device receives fourth downlink data from the first network device.

26. The method of claim 25, wherein the step of determining the position of the probe is performed,

the terminal device receives fourth downlink data, including: the terminal equipment receives the fourth downlink data from the second network equipment;

the terminal device sending indication information for indicating that the fourth downlink data is not successfully received, including: the terminal device sends a first status report to the second network device, wherein the first status report comprises the indication information.

27. The method of claim 25, wherein the step of determining the position of the probe is performed,

the terminal device receives fourth downlink data, including: the terminal equipment receives the fourth downlink data from the third network equipment;

the terminal device sending indication information for indicating that the fourth downlink data is not successfully received, including: the terminal device sends a second status report to a third network device, wherein the second status report comprises the indication information.

28. The method according to any one of claims 25 to 27, further comprising:

the terminal equipment receives a radio resource control release message from the network equipment, wherein the radio resource control release message comprises Y, Y is the number of cell reselection in the transmission process of the small data packet, and Y is a positive integer;

The terminal equipment initiates a small data packet transmission process;

the terminal equipment records the times of cell reselection;

and under the condition that the number of cell reselection recorded by the terminal equipment is more than or equal to Y, the terminal equipment is switched to a wireless resource control idle state, or the terminal equipment sends a recovery request message of non-small data packet transmission to the network equipment.

29. A method of data transmission, comprising:

the third network equipment receives fourth downlink data from the second network equipment, wherein the fourth downlink data is small data;

the third network device sends the fourth downlink data to a terminal device;

the third network device receives a second status report from the terminal device, wherein the second status report comprises indication information for indicating that the terminal device does not successfully receive the fourth downlink data;

and the third network equipment sends a first status report to the second network equipment according to the second status report, wherein the first status report comprises indication information for indicating that the terminal equipment does not successfully receive the fourth downlink data.

30. The method of claim 29, further comprising:

The third network device receives a fourth request message from the second network device, where the fourth request message is used to request a status report of the fourth downlink data.

31. The method according to claim 29 or 30, characterized in that the method further comprises:

and the third network equipment releases the link with the terminal equipment and stops communicating with the terminal equipment.

32. A data transmission apparatus, comprising:

a processor for executing a computer program stored in a memory to cause the apparatus to perform the method of any one of claims 1 to 11 or to cause the apparatus to perform the method of any one of claims 12 to 24 or to cause the apparatus to perform the method of any one of claims 25 to 28 or to cause the apparatus to perform the method of any one of claims 29 to 31.

33. The apparatus of claim 32, further comprising the memory.

34. A computer-readable storage medium, on which a computer program is stored which, when run on a computer, causes the computer to perform the method of any one of claims 1 to 11, or to cause the computer to perform the method of any one of claims 12 to 2, or to cause the computer to perform the method of any one of claims 25 to 28, or to cause the computer to perform the method of any one of claims 29 to 31.

35. A computer program product comprising instructions for performing the method of any one of claims 1 to 11 or for performing the method of any one of claims 12 to 24 or for performing the method of any one of claims 25 to 28, the computer program product comprising instructions for performing the method of any one of claims 29 to 31.

36. A communication system, comprising a first network device and a second network device,

wherein the terminal device is configured to perform the method of any of claims 1 to 11 and the network device is configured to perform the method of any of claims 12 to 24.