Patent Description:
Architecture of a <NUM> network is innovative and flexible in networking. In the <NUM> network, a base station on a radio access network side is separated into two functional entities, a centralized unit (CU) and a distributed unit (DU), and one base station includes one CU and at least one DU. In a CU-DU separated network architecture, a delay-insensitive network function is placed in the CU, and a delay-sensitive network function is placed in the DU. The CU and the DU perform transmission and connection through an ideal or non-ideal fronthaul.

<FIG> is a schematic diagram of a connection of multiple DUs under one base station and a terminal in the existing art, and as shown in <FIG>, in order to provide a higher rate to a user, the existing wireless networking technology supports the connection of multiple DUs under one base station and a terminal, and the terminal may simultaneously send and receive data from two or more DUs.

In the existing CU/DU separated architecture, for a CU/DU higher layer separated solution, PDCP and layers above PDCP are placed in the CU, and RLC and layers below RLC are placed in the DU. When the terminal is connected to the multiple DUs under one base station, a base station CU entity may offload downlink PDCP PDU data to two or more DUs for transmission to the terminal. During data transmission, if a DU has a terminal traffic connection "outage" (outage is defined herein as short-term link quality degradation), in order to reduce data transmission delay and packet loss, the DU needs to send an outage message (which is also referred to as a link quality degradation message hereinafter) to the CU, where the outage message carries a maximum PDCP serial number successfully and continuously sent by the DU. The CU receives the outage message of the DU. The CU may determine which PDCP PDUs sent to the DU are not successfully sent by the DU according to the maximum PDCP SN serial number carried by the outage message, and the CU may send the part of PDCP PDU data, which is not successfully sent, to another DU for transmission to the terminal, thereby reducing data sending time delay and packet loss. When link quality of a DU having an "outage" resumes, the DU may send a "RESUME" message of a terminal traffic connection to the CU to notify the CU that the link quality of the terminal connection has resumed, so that the CU may resume to send traffic bearer data of the terminal to the DU for transmission. However, in the existing art, the CU sends data unsuccessfully transmitted by a source DU to a target DU for retransmission, but the target DU may not identify whether the data is retransmitted data or newly transmitted data, and arranges the data at the end of a sending queue, thereby resulting in an increase in data transmission delay.

In addition, a base station dual connectivity technology is also supported in the existing wireless communication technology, a user may maintain a connection to two or more base stations, and traffic bearer data of a terminal may be offloaded to the two or more base stations for transmission. <FIG> is a schematic diagram of base station dual connectivity in the existing art. As shown in <FIG>, an anchor base station refers to a base station connected to a core network, and the anchor base station is used for receiving traffic bearer data of a terminal sent by the core network. An offload base station refers to a base station which is connected to the anchor base station and is used for receiving traffic bearer data of a terminal offloaded by the anchor base station. A user terminal is connected to the anchor base station and the offload base station simultaneously.

When the base station dual connectivity technology is used and a base station uses a CU/DU separated structure, after a DU of the base station has short-term quality deterioration of a terminal traffic link, in the existing dual connectivity technology, data does not continue to be transmitted until terminal link quality of the DU of the base station resumes, and the data unsuccessfully transmitted on the DU of the base station cannot be sent to another base station for transmission when the DU of the base station has link quality deterioration of a connection to a terminal, thereby resulting in an increase in data transmission delay or even packet loss. Therefore, in the existing dual connectivity technology, when a base station uses the CU/DU separated structure, even if quality of a downlink data transmission link of a DU is deteriorated, a network side cannot actively take measures to perform relevant adjustments, thereby resulting in an increase in data transmission delay or even packet loss.

No solution has been proposed to address the problem that in the base station dual connectivity technology in the existing art, when a base station uses the CU/DU separated structure, even if the quality of a downlink data transmission link of a DU is deteriorated, the network side cannot actively take measures to perform relevant adjustments, thereby resulting in an increase in data transmission delay or even packet loss.

Further technology is also known from <NPL>.

Further technology is also known from <NPL>.

Embodiments of the present disclosure provide a data transmission method and apparatus, so as to at least solve a problem that in a base station dual connectivity technology in the existing art, when a base station uses a CU/DU separated structure, even if quality of a downlink data transmission link of a DU is deteriorated, a network side cannot actively take measures to perform relevant adjustments, thereby resulting in an increase in data transmission delay or even packet loss.

By the present disclosure, a source base station detects, through a DU, link quality degradation of a connection to a terminal; the source base station determines, through a CU, data unsuccessfully transmitted by the DU; the source base station sends the data unsuccessfully transmitted by the DU via the downlink data frame to the target base station through the CU, transmits the data unsuccessfully transmitted to the terminal through the target base station, or the target base station receives link quality degradation message of an original base station so as to stop sending the offload data to the source base station and transmit the data unsuccessfully transmitted indicated by a maximum serial number of the data which has been transmitted continuously and successfully in the message to the terminal, which solves the problem that in the base station dual connectivity technology in the existing art, when a base station uses a CU/DU separated structure, even if quality of a DU downlink data transmission link is deteriorated, a network side cannot actively take measures to perform relevant adjustments, thereby resulting in an increase in data transmission delay or even packet loss. By retransmitting data on a base station with good link quality, the data transmission delay is reduced, packet loss is reduced, and user experience is improved.

The drawings described herein are used to provide a further understanding of the present disclosure, and form a part of the present application. The exemplary embodiments and descriptions thereof in the present disclosure are used to explain the present disclosure and do not limit the present disclosure in any improper way. Among the drawings:.

Hereinafter the present disclosure will be described in detail with reference to the drawings and in conjunction with embodiments. It is to be noted that if not in collision, the embodiments and features therein in the present application may be combined with each other.

It is to be noted that the terms "first", "second" and the like in the description, claims and above drawings of the present disclosure are used to distinguish between similar objects and are not necessarily used to describe a particular order or sequence.

A method embodiment provided by the embodiment <NUM> of the present application may be executed in a mobile terminal, a computer terminal or other similar computing apparatuses. Taking the method embodiment to be executed in a mobile terminal as an example, <FIG> is a block diagram of hardware of a mobile terminal of a data transmission method according to an embodiment of the present disclosure, as shown in <FIG>, a mobile terminal <NUM> may include one or two (only one is shown in <FIG>) processors <NUM> (the processor <NUM> may include, but is not limited to, a processing device such as a microprocessor (MCU), a Field Programmable Gate Array (FPGA), or the like), a memory <NUM> used for storing data, and a transmission apparatus <NUM> used for implementing a communication function. It should be understood by those skilled in the art that the structure shown in <FIG> is merely illustrative and not intended to limit the structure of the electronic apparatus described above. For example, the mobile terminal <NUM> may further include more or fewer components than the components shown in <FIG> or may have a configuration different from the configuration shown in <FIG>.

The memory <NUM> may be configured to store software programs and modules of application software, such as program instructions/modules corresponding to the data transmission method in the embodiments of the present disclosure. The one or more processors <NUM> execute the software programs and modules stored in the memory <NUM> to perform various functional applications and data processing, that is, to implement the method described above. The memory <NUM> may include a high-speed random access memory, and may further include a nonvolatile memory such as one or two magnetic storage devices, a flash memory or other nonvolatile solid-state memories. In some examples, the memory <NUM> may further include a memory that is remotely disposed with respect to the processor <NUM>. The remote memory may be connected to the mobile terminal <NUM> via a network. Examples of the above network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network and a combination thereof.

The transmission apparatus <NUM> is configured to receive or send data via a network. Specific examples of the above networks may include a radio network provided by a communication provider of the mobile terminal <NUM>. In one example, the transmission apparatus <NUM> includes a network interface controller (NIC), which may be connected to another network device via a base station and thus be capable of communicating with the Internet. In one example, the transmission apparatus <NUM> may be a Radio Frequency (RF) module, which is used for communicating with the Internet in a wireless manner.

Based on the mobile terminal described above, an embodiment of the present disclosure provides a data transmission method. <FIG> is a flowchart <NUM> of a data transmission method according to an embodiment of the present disclosure. As shown in <FIG>, the method includes steps described below.

In step S402, a source base station detects, through a DU, link quality degradation of a connection to a terminal;
In step S404, the source base station determines, through a CU, data unsuccessfully transmitted by the DU, and sends the data unsuccessfully transmitted by the DU via a downlink data frame to a target base station through the CU, where the downlink data frame is used for the target base station to transmit the data unsuccessfully transmitted to the terminal; or
In step S406, the source base station sends a link quality degradation message of the source base station to the target base station, where the link quality degradation message carries a serial number of data successfully transmitted, and the link quality degradation message is used for the target base station to determine the data unsuccessfully transmitted by the DU according to the serial number, stop sending offload data to the source base station and transmit the data unsuccessfully transmitted by the DU to the terminal.

Through the above steps, a problem that in the base station dual connectivity technology in the existing art, when a base station uses a CU/DU separated structure, even if quality of a DU downlink data transmission link is deteriorated, a network side cannot actively take measures to perform relevant adjustments, thereby resulting in an increase in data transmission delay or even packet loss is solved. By retransmitting data on a base station with good link quality, the data transmission delay is reduced, packet loss is reduced, and user experience is improved. Optionally, the step in which the source base station sends the data unsuccessfully transmitted by the DU via the downlink data frame to the target base station through the CU includes a step described below. The source base station sends the downlink data frame to the target base station through an interface between the source base station and the target base station, where the downlink data frame carries the data unsuccessfully transmitted by the DU.

Optionally, after the source base station sends the data unsuccessfully transmitted by the DU via the downlink data frame to the target base station through the CU, the method further includes a step described below. The source base station stops sending data to the DU, sends data received from a core network to the target base station, and transmits the data to the terminal through the target base station.

The step in which the source base station determines, through the CU, the data unsuccessfully transmitted by the DU includes steps described below. The source base station sends a link quality degradation message to the CU through the DU, where the link quality degradation message carries a serial number of data successfully transmitted by the DU; and the source base station determines, through the CU, the data unsuccessfully transmitted by the DU according to the serial number.

Optionally, the method further includes steps described below. The source base station detects through the DU that a link of the connection to the terminal has resumed to normal; the source base station sends, through the DU to the CU, a resume message that the link has resumed to normal; and the source base station resumes, through the CU, sending traffic bearer data of the terminal to the DU.

Optionally, after the source base station sends the link quality degradation message to the CU through the DU, the method further includes steps described below. the source base station starts a timer through the CU, and in response to receiving the resume message from the DU before the timer times out, the timer is cleared; and in response to failing to receive the resume message from the DU until the timer times out, a traffic connection of the terminal is released.

Optionally, after the source base station sends the link quality degradation message of the source base station to the target base station, the method further includes steps described below. The source base station detects through the DU that a link of the connection to the terminal has resumed to normal; the source base station sends, through the DU to the CU, a resume message that the link has resumed to normal; and the source base station sends the resume message to the target base station through the CU, where the resume message is used for the target base station to resume sending the offload data to the source base station.

Optionally, the downlink data frame carries a retransmission data indication, where the retransmission data indication is used for instructing the target base station to identify retransmission data and perform preferential processing.

An embodiment of the present disclosure further provides a data transmission method. <FIG> is a flowchart <NUM> of a data transmission method according to an embodiment of the present disclosure. As shown in <FIG>, the method includes steps described below.

In step S502, a target base station receives data unsuccessfully transmitted by a DU which is sent by a source base station through a downlink data frame, where the downlink data frame is transmitted by the source base station through a CU, and the data unsuccessfully transmitted by the DU is determined through the CU in a case where the source base station detects, through the DU, link quality degradation of a connection to a terminal, and transmits the data unsuccessfully transmitted which is carried in the downlink data frame to the terminal; or.

In step S504, the target base station receives a link quality degradation message of the source base station sent by the source base station, where the link quality degradation message carries a serial number of data successfully transmitted, determines the data unsuccessfully transmitted by the DU according to the serial number, stops sending offload data to the source base station and sends the data unsuccessfully transmitted by the DU to the terminal.

Optionally, the method further includes steps described below. While or after the target base station transmits the data unsuccessfully transmitted to the terminal according to a retransmission data indication, the target base station receives data which is sent by a core network and forwarded by the source base station; and the target base station transmits the data to the terminal. Optionally, the downlink date frame further carries a retransmission data indication, and after the target base station receives the data unsuccessfully transmitted by the DU which is sent by the source base station through the downlink data frame, the method further includes steps described below. The target base station identifies the data as retransmission data through the retransmission data indication, a transmission priority of the data is increased and the retransmission data is sent preferentially.

Optionally, after the data unsuccessfully transmitted by the DU is determined according to the serial number, the offload data to the source base station is stopped sending and the data unsuccessfully transmitted by the DU is sent to the terminal, the method further steps described below. The target base station receives a resume message sent by the source base station through the CU, where the resume message is sent to the CU through the DU after the source base station detects through the DU that a link connection to the terminal has resumed to normal; and the target base station resumes sending the offload data to the source base station according to the resume message.

In the embodiment of the present disclosure, a "retransmission data indication" field is added in a definition of a downlink data frame for transmitting user plane data between network elements, and may be applied to an interface (F1 interface) between a CU and a DU inside a base station and an interface (X2 or XN interface) between base stations. If the field exists in the downlink data frame, the data is retransmission data, and if the field does not exist, the data is non-retransmission data; or if a value of the field is TRUE, the data is the retransmission data and if the value of the field is FALSE, the data is the non-retransmission data.

When the definition of the downlink data frame is applied to the interface between a CU and a DU, The CU sends data unsuccessfully transmitted data by one DU to a target DU for transmission through the downlink data frame. When the target DU identifies, through the "retransmission data indication" field in the downlink data frame, that the data is the retransmission data, a sending priority of the data is increased, and the data is sent preferentially.

When the definition of the downlink data frame is applied to the interface between base stations, a source base station sends data unsuccessfully transmitted data by the source base station to the target base station for transmission through the downlink data frame. When the target base station identifies, through the "retransmission data indication" field in the downlink data frame, that the data is the retransmission data, the sending priority of the data is increased, and the data is sent preferentially.

After a CU node of an anchor base station receives an outage message of a terminal traffic connection reported by a DU of the anchor base station, the CU determines which PDCP PDUs are not successfully transmitted in the DU through, "maximum packet data convergence protocol (PDCP) serial number (SN) submitted continuously and successfully" IE, in the outage message, sends part of PDCP PDUs to an offload base station for transmission through the downlink data frame between base stations, indicates that the data is retransmission data in the "retransmission data indication" of the downlink data frame, stops sending data to the DU of the anchor base station, and sends subsequent terminal traffic bearer data received from the core network to the offload base station for transmission. When the offload base station receives the downlink data frame forwarded by the anchor base station, if the offload base station identifies, through the 'retransmission data indication' field in the downlink data frame, that the data is the retransmission data, the sending priority of the data is increased, and the data is sent preferentially. After the CU node of the anchor base station receives a resume message of the terminal traffic connection reported by the DU of the anchor base station, the anchor base station resumes sending terminal traffic bearer data to the DU of the anchor base station. Optionally, after receiving the outage message of a terminal connection, the CU of the anchor base station may start a timer, and in response to receiving a resume message of the terminal connection from the DU before the timer times out, the CU stops the timer. In response to failing to receive the resume message of the terminal connection reported by the DU until the timer times out, the CU may initiate a terminal RRC connection release process to release a traffic connection of the terminal.

After the CU node of the offload base station receives the outage message of the terminal traffic connection reported by the DU of the offload base station, If the interface between base stations may directly identify the outage message, the offload base station directly forwards the outage message to the anchor base station, otherwise the offload base station CU constructs the outage message sent to the anchor base station, and the offload base station CU parses, "maximum PDCP SN submitted continuously and successfully" IE, in the received outage message from the DU, and a value of IE is filled in IE, "maximum PDCP SN submitted continuously and successfully", in the constructed outage message sent to the anchor base station. The offload base station sends the outage message to the anchor base station. After the CU node of the offload base station receives the resume message of the terminal traffic connection reported by the DU of the offload base station DU, if the interface between base stations may directly identify the resume message, the offload base station directly forwards the resume message to the anchor base station, otherwise the offload base station CU constructs the resume message sent to the anchor base station, where the resume message is used for notifying the anchor base station that the offload base station terminal traffic transmission link quality has resumed.

After the anchor base station receives the outage message of the terminal traffic connection sent by the offload base station, the anchor base station determines, through "maximum PDCP SN submitted continuously and successfully" IE in the outage message, which PDCP PDUs on the offload base station have not been successfully transmitted, sends this part of PDCP PDUs to the terminal on the anchor base station; and the anchor base station stops sending the terminal traffic bearer data to the offload base station. After the anchor base station receives resume message of the terminal traffic connection reported by the offload base station, the anchor base station resumes sending the terminal traffic bearer data to the offload base station. Optionally, after receiving the terminal traffic connection outage message by the offload base station, the anchor base station may start a timer, and in response to receiving the resume message of the terminal traffic connection of the offload base station before the timer times out, the anchor base station stops the timer. After the timer times out, in response to failing to receiving the resume message of the terminal traffic connection reported by the offload base station, the anchor base station may initiate a bearer type modification process to modify traffic bearer offloaded to the offload base station to a bearer type of being transmitted separately by the anchor base station, or the anchor base station may initiate an offload base station node release process.

When the base station dual connectivity technology is used and one base stations uses the CU / DU separated structure, after a terminal traffic connection outage occurs in the DU of the base station, in the existing dual connectivity technology, data does not continues to be transmitted until traffic link quality of the DU of the base station resumes, thereby resulting in an increase in data transmission delay or even packet loss. After the technology of the present disclosure is used, the network side can retransmit data on a base station with good link quality, thereby reducing data transmission delay and reducing packet loss. By defining the "retransmission data indication" field in the downlink data frame between network elements to identify whether the data is retransmission data, thereby increasing the sending priority of the data and reducing data sending delay.

The present disclosure will be described below in conjunction with the drawings and embodiments.

<FIG> is a schematic diagram of a definition of a downlink data frame for transmitting user plane data between network elements according to an embodiment of the present disclosure. As shown in <FIG>, the definition may be applied to an interface (F1 interface) between a CU and a DU inside a base station and an interface (X2 or XN interface) between base stations. The downlink data frame includes the "retransmission data indication" field provided by the present disclosure, and other fields of the downlink data frame are not indicated in the schematic diagram. If the field exists, the data is retransmission data, and if the field does not exist, the data is non-retransmission data; or if a value of the field is TRUE, the data is retransmission data and if the value of the field is FALSE, the data is non-retransmission data.

When the definition of the downlink data frame is applied to the interface between the CU and the DU, The CU sends data unsuccessfully transmitted data by one DU to a target DU for transmission via the downlink data frame. When the target DU identifies, through the "retransmission data indication" field in the downlink data frame, that the data is the retransmission data, a sending priority of the data is increased, and the data is sent preferentially. When the definition of the downlink data frame is applied to the interface between base stations, a source base station sends data unsuccessfully transmitted data by the source base station to the target base station for transmission through the downlink data frame. When the target base station identifies, through the "retransmission data indication" field in the downlink data frame, that the data is the retransmission data, the sending priority of the data is increased, and the data is sent preferentially.

<FIG> is a flowchart of processing after an outage occurs in a DU of an anchor base station according to an embodiment of the present disclosure. As shown in <FIG>, the flowchart includes steps described below.

In step <NUM>, a terminal establishes a dual connection with the anchor base station and the offload base station. the anchor base station is a base station with a CU/DU separated architecture. The offload base station may be the CU/DU separated architecture or an integrated architecture.

In step <NUM>, the DU of the anchor base station detects a terminal link quality outage. In step <NUM>, the DU of the anchor base station reports an outage message of a terminal traffic connection to the CU of the anchor base station.

In step <NUM>, the anchor base station stops sending terminal traffic downlink data to the DU. In step <NUM>, the CU of the anchor base station determines, through "maximum PDCP SN submitted continuously and successfully" IE in the outage message, which PDCP PDUs are not successfully transmitted in the DU, sends the part of PDCP PDUs, through the downlink data frame, to the offload base station for transmission, and sends, through the downlink data frame, all of subsequent terminal traffic bearer data received from the core network to the offload base station for transmission.

In step <NUM>, when the offload base station identifies, through the "retransmission data indication" field in the downlink data frame, that the data is the retransmission data, the sending priority of the data is increased, and the data is sent preferentially.

In step <NUM>, after the DU of the anchor base station detects that the terminal traffic link quality resumes, a resume message of the terminal connection is sent to the CU.

In step <NUM>, after the CU node of the anchor base station receives the resume message reported by the DU of the anchor base station, the anchor base station resumes sending data to the DU of the anchor base station.

Optionally, after step <NUM>, in response to receiving the outage message of the terminal connection, the CU of the anchor base station may start a timer, and in response to receiving the resume message before the timer times out, the CU stops the timer. In response to failing to receive the resume message reported by the DU until the timer times out, the CU may initiate a terminal RRC connection release process to release a connection to the terminal.

<FIG> is a flowchart of processing after an outage occurs in a DU of an offload base station according to an embodiment of the present disclosure. As shown in <FIG>, the flowchart includes steps described below. In step <NUM>, the terminal establishes a dual connection to the anchor base station and the offload base station. The offload base station is a base station with the CU/DU separated architecture. The anchor base station may be the CU/DU separated architecture or the integrated architecture.

In step <NUM>, the DU of the offload base station detects the terminal link quality outage.

In step <NUM>, the DU of the offload base station reports the outage message of the terminal traffic connection to the CU of the offload base station.

In step <NUM>, after the CU node of the offload base station receives the outage message of the terminal traffic connection reported by the DU of the offload base station, the offload base station sends the outage message to the anchor base station, where the outage message includes "maximum PDCP SN submitted continuously and successfully" IE.

In step <NUM>, after receiving the outage message of the terminal traffic connection sent by the offload base station, the anchor base station stops sending the terminal traffic bearer data to the offload base station. The anchor base station determines, through "maximum PDCP SN submitted continuously and successfully" IE in the outage message, which PDCP PDUs are not successfully transmitted in the DU, sends the part of PDCP PDUs to the terminal on the anchor base station, and sends all of subsequent terminal traffic bearer data received from the core network to the terminal on the anchor base station. In step <NUM>, after the DU of the offload base station detects that the terminal traffic link quality resumes, the resume message of the terminal traffic connection is sent to the CU of the offload base station.

In step <NUM>, after the CU of the offload base station receives the resume message of the terminal traffic connection sent by the DU of the offload base station, the offload base station sends the resume message to the anchor base station.

In step <NUM>, after the anchor base station receives the resume message of the terminal traffic connection reported by the offload base station, the anchor base station resumes sending the terminal traffic bearer data to the offload base station.

Optionally, after step <NUM>, in response to receiving the terminal traffic connection outage message sent by the offload base station, the anchor base station may start a timer, and in response to receiving the resume message of the terminal traffic connection of the offload base station before the timer times out, the anchor base station stops the timer. After the timer times out, in response to failing to receiving the resume message of the terminal traffic connection reported by the offload base station, the anchor base station may initiate modification process of a terminal traffic bearer type to modify the terminal traffic bearer type to be transmitted separately by the anchor base station, or the anchor base station may initiate an offload base station node release process.

It should be understood that the other embodiments except the embodiments corresponding to <FIG> are for illustrative purpose only.

According to another embodiment of the present disclosure, a data transmission apparatus, applied to a source base station, is further provided. <FIG> is a block diagram <NUM> of a data transmission apparatus according to an embodiment of the present disclosure. As shown in <FIG>, the apparatus includes a detection module <NUM>, a first sending module <NUM> and a second sending module <NUM>.

The detection module <NUM> is configured to detect, through a DU, link quality degradation of a connection to a terminal; The first sending module <NUM> is configured to determine, through a CU, data unsuccessfully transmitted by the DU, and send the data unsuccessfully transmitted by the DU via a downlink data frame to a target base station through the CU, where the downlink data frame is used for the target base station to transmit the data unsuccessfully transmitted to the terminal; or the second sending module <NUM> is configured to send a link quality degradation message of the source base station to the target base station, where the link quality degradation message carries a serial number of data successfully transmitted, and the link quality degradation message is used for the target base station to determine the data unsuccessfully transmitted by the DU according to the serial number, stop sending offload data to the source base station and transmit the data unsuccessfully transmitted by the DU to the terminal.

The functions of the detection module <NUM>, the first sending module <NUM> and the second sending module <NUM> are implemented by a controller and a processor of a base station.

According to another embodiment of the present disclosure, a data transmission apparatus, applied to a target base station, is further provided. <FIG> is a block diagram <NUM> of a data transmission apparatus according to an embodiment of the present disclosure. As shown in <FIG>, the apparatus includes a first receiving module <NUM> and a second receiving module <NUM>.

The first receiving module <NUM> is configured to receive data unsuccessfully transmitted by a DU which is sent by a source base station through a downlink data frame, where the downlink data frame is transmitted by the source base station through a CU, and the data unsuccessfully transmitted by the DU is determined through the CU in a case where the source base station detects, through the DU, link quality degradation of a connection to a terminal through the DU, and transmit the data unsuccessfully transmitted which is carried in the downlink data frame to the terminal; or the second receiving module <NUM> is configured to receive a link quality degradation message of the source base station sent by the source base station, where the link quality degradation message carries a serial number of data successfully transmitted, determine the data unsuccessfully transmitted by the DU according to the serial number, stop sending offload data to the source base station and send the data unsuccessfully transmitted by the DU to the terminal.

The functions of the first receiving module <NUM> and the second receiving module <NUM> are implemented by a controller and a processor of a base station.

According to an embodiment of the present disclosure, a storage medium is further provided. The storage medium includes a stored program which, when executed, executes any one of above-mentioned methods.

Optionally, in the present embodiment, the storage medium above-mentioned may be configured to store program codes for performing steps described below. In S11, a source base station detects, through a DU, link quality degradation of a connection to a terminal;.

Optionally, in the present embodiment, the storage medium above-mentioned may be configured to store program codes for performing steps described below.

In S21, a target base station receives data unsuccessfully transmitted by a DU which is sent by a source base station through a downlink data frame, where the downlink data frame is transmitted by the source base station through a CU, and the data unsuccessfully transmitted by the DU is determined through the CU in a case where the source base station detects, through the DU, link quality degradation of a connection to a terminal, and transmits the data unsuccessfully transmitted which is carried in the downlink data frame to the terminal; or
In S22, the target base station receives a link quality degradation message of the source base station sent by the source base station, where the link quality degradation message carries a serial number of data successfully transmitted, determines the data unsuccessfully transmitted by the DU according to the serial number, stops sending offload data to the source base station and sends the data unsuccessfully transmitted by the DU to the terminal.

Optionally, in the present embodiment, the storage medium above-mentioned may include, but is not limited to, a USB flash disk, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk, an optical disk or another medium capable of storing the program codes.

According to an embodiment of the present disclosure, a processor is further provided. The processor is configured to execute a program which, when executed, performs the steps of any one of above-mentioned methods.

Optionally, in the present embodiment, the program described above is used for performing steps described below. In S31, a source base station detects, through a DU, link quality degradation of a connection to a terminal;.

Optionally, in the present embodiment, the program described above is further used for performing steps described below.

In S41, a target base station receives data unsuccessfully transmitted by a DU which is sent by a source base station through a downlink data frame, where the downlink data frame is transmitted by the source base station through a CU, and the data unsuccessfully transmitted by the DU is determined through the CU in a case where the source base station detects, through the DU, link quality degradation of a connection to a terminal, and transmits the data unsuccessfully transmitted which is carried in the downlink data frame to the terminal; or.

In S42, the target base station receives a link quality degradation message of the source base station sent by the source base station, where the link quality degradation message carries a serial number of data successfully transmitted, determines the data unsuccessfully transmitted by the DU according to the serial number, stops sending offload data to the source base station and sends the data unsuccessfully transmitted by the DU to the terminal. Optionally, for specific examples in the present embodiment, reference may be made to the examples described in the above-mentioned embodiments and optional implementation manners, and repetition will not be made in the present embodiment.

Claim 1:
A data transmission method, comprising:
detecting (S402, <NUM>), by a distributed unit, DU, of a source base station, a degradation of a link quality of a connection between the source base station and a terminal (<NUM>);
sending (<NUM>), by the DU, a link quality degradation message to a centralized unit, CU, of the source base station, wherein the link quality degradation message carries a serial number of data successfully transmitted by the DU;
in a case where the source base station is an anchor base station with a CU/DU separated architecture, and a target base station is an offload base station with an integrated architecture: stopping sending (<NUM>), by the CU, traffic downlink data to the DU, determining (S403, <NUM>), by the CU of the source base station, data unsuccessfully transmitted by the DU according to the serial number, and sending (<NUM>), by the CU, the data unsuccessfully transmitted by the DU and all subsequent terminal traffic bearer data from the core network via a downlink data frame to the target base station, wherein a dual connection between the terminal (<NUM>), the source base station, and the target base station are established (<NUM>) to perform offloading between the base stations; and the downlink data frame is used for the target base station to transmit the data unsuccessfully transmitted by the DU and all subsequence terminal traffic bearer data received from the core network to the terminal (<NUM>);
in a case where the source base station is an offload base station with a CU/DU separated architecture, and a target base station is an anchor base station with an integrated architecture: sending (S404, <NUM>), by the CU of the source base station, the link quality degradation message of the source base station to the target base station, wherein a dual connection between the terminal (<NUM>), the source base station, and the target base station are established (<NUM>) to perform offloading between the base stations; and the link quality degradation message is used for the target base station to stop (<NUM>) sending terminal traffic bearer data to the source base station, determine (<NUM>) the data unsuccessfully transmitted by the DU according to the serial number, and send (<NUM>) the data unsuccessfully transmitted by the DU and all of subsequent terminal traffic bearer data received from a core network to the terminal (<NUM>).