RU2779030C2 - Device and method for data transmission in duplication mode in cu-du architecture - Google Patents

Abstract

FIELD: radio communication.

SUBSTANCE: invention relates to the field of radio communication, in particular to a technology of data transmission in a duplication mode in CU-DU architecture. Options of implementation of the present invention provide for a method for data transmission in a duplication mode in centralized unit-distributed unit (hereinafter – CU-DU) architecture. In possible implementation, during the establishment of a user plane tunnel between CU and DU, by means of exchange of information about end points of an uplink tunnel and information about end points of a downlink tunnel, DU provides a main tract identifier of at least two logical channels corresponding to a data transmission radio channel to CU, thereby implementing a duplication mode of the data transmission radio channel.

EFFECT: prevention of violation of data transmission between CU and DU, even if an activated duplication mode is deactivated.

25 cl, 10 dwg

Description

The field of technology to which the invention belongs

Embodiments of the present invention relate to the field of radio communication and, in particular, to the technology of data transmission in duplication mode (duplication) in the CU-DU architecture.

State of the art

In a radio communication system, various types of data are transmitted between a terminal-side device and an access network-side device in the uplink and downlink using radio bearers (radio bearer, RB) at various protocol layers defined by the 3rd Generation Partnership Project (the 3rd ^Generation Partnership Project, 3GPP). For example, control signaling is transmitted over a signaling radio bearer, or service data is transmitted over a data radio bearer. These protocol layers include the physical (PHY) layer, the Media Access Control (MAC) layer, the Radio Link Control (RLC) layer, and the Packet Data Convergence Protocol (PDCP) layer. ), a Radio Resource Control (RRC) layer, and the like.

The access network side device may be further defined, according to the protocol layers, as an architecture including a central unit (CU) and a distributed unit (DU). A control plane connection and a user plane connection are established between the CU and the DU. A user plane connection is also called a user plane (UP) tunnel. One user plane tunnel is defined by one uplink tunnel endpoint in the CU and one downlink tunnel endpoint in the DU. The CU is configured to implement PDCP layer functions and RRC layer functions, and the DU is configured to implement PHY layer functions, MAC layer functions, and RLC layer functions.

With the development of 5th generation communication technologies for one radio channel, one PDCP entity in the PDCP layer corresponds to at least two RLC entities in the RLC layer. Some or all of the data about one PDCP entity is transmitted in at least two RLC entities in duplicate. This processing mode is called duplication. One duplication mode is specific for one radio channel.

It is necessary to solve a currently relevant technical problem, which is to provide a method for implementing the duplication mode for a radio bearer in a CU-DU architecture.

Disclosure of the essence of the invention

Embodiments of the present invention provide a method for transmitting data in duplex mode in a CU-DU architecture for establishing a CU-DU connection in duplex mode.

A first aspect of embodiments of the present invention provides a method for transmitting data in duplication mode in a CU-DU architecture, including the steps of:

transmitting, by the CU, a first message to the DU, where the first message contains information indicating at least two uplink tunnel endpoints for the data radio duplication mode that are at the interface between the CU and the DU; and receiving, by the CU, a second message transmitted by the DU, the second message containing information indicating at least two downlink tunnel endpoints for the data radio bearer that are at the interface between the CU and the DU, and identifying the main path data radio channel. In an implementation, at least two downlink tunnel endpoints are in a one-to-one correspondence with at least two uplink tunnel endpoints.

By applying the solution provided in the first aspect, in the process of establishing at least two user plane tunnels between a CU and a DU by exchanging uplink tunnel endpoint information and downlink tunnel endpoint information, the DU ensures the identity of the main path to the CU so that the CU and DU know which user plane tunnel corresponds to the main path, and can additionally establish a connection between the main path and the user plane tunnel corresponding to the main path. Thus, a duplication mode is implemented for the radio data transmission channel from CU to DU.

In a first aspect, the first message contains information indicating at least two uplink tunnel endpoints (indicating the need to establish at least two user plane tunnels), so the DU can configure the data radio duplication mode by default.

In the first aspect, either the CU or the DU may determine which user plane tunnel corresponds to the primary path, but the primary path identifier notifies the CU via the DU using the second message.

Based on the first aspect, in the first possible implementation of the first aspect, the first message further contains information instructing to configure the data radio duplication mode. Applying the solution provided in the first possible implementation, the CU uses the first message to explicitly indicate to the DU that the data radio duplication mode should be configured.

Based on the first aspect or the first possible implementation of the first aspect, in the second possible implementation of the first aspect, the main path identifier is the identifier indicated by the information contained in the second message of the path corresponding to only one of the at least two downlink tunnel endpoints. In a second possible implementation of the first aspect, the DU may notify the path identifier corresponding to only one downlink tunnel endpoint, and thus the path identifier corresponding to only one downlink tunnel endpoint is the primary path identifier.

Based on any of the first aspect, through the second possible implementation of the first aspect, in the third possible implementation of the first aspect,

the first message further comprises information indicating an uplink tunnel endpoint of the at least two uplink tunnel endpoints that corresponds to the main path; or the second message further comprises information indicating a downlink tunnel endpoint of at least two downlink tunnel endpoints that corresponds to the main path; or an uplink tunnel endpoint of at least two uplink tunnel endpoints that corresponds to the main path is predetermined by the protocol; or a downlink tunnel endpoint of at least two downlink tunnel endpoints that corresponds to the main path is predetermined by the protocol.

In a third possible implementation of the first aspect, the user plane tunnel corresponding to the main path may be defined by the CU or DU, or predefined by the protocol.

Based on any one of the first aspect through the third possible implementation of the first aspect, in the fourth possible implementation of the first aspect, the method further includes: notifying by the CU the identifier of the main radio data link path to the terminal side device via the DU.

A fourth possible implementation of the first aspect allows the terminal side device to learn the main path, so that the main path is determined for the CU, DU, and the terminal side device.

A second aspect of the embodiments of the present invention provides a method for transmitting data in duplication mode in a CU-DU architecture, including the following:

transmitting, by the CU, to the DU, a signaling radio bearer identifier and indication information used to indicate to configure a signaling radio bearer duplication mode; and receiving, by the CU, the signaling radio bearer duplication mode configuration and the primary signaling radio bearer path identifier transmitted by the DU.

By applying the solution provided in the second aspect, the DU can configure the signaling radio bearer according to the indication of the CU so that the CU learns the main path of the signaling radio bearer.

Based on the second aspect, in the first possible implementation of the second aspect, the method further includes: transmitting by the CU an interface CU-DU message on the DU, wherein

when the signaling radio bearer duplication mode is inactive, the CU-DU interface message includes one RRC message belonging to the signaling radio bearer; or

when the signaling radio bearer duplication mode is active, the CU-DU interface message includes at least two RRC messages with the same PDCP serial number that belong to the signaling radio bearer.

The first possible implementation of the second aspect provides for the implementation of the transmission of the RRC message by the CU when the duplication mode is active or inactive.

Based on the second aspect, in a second possible implementation of the second aspect, the method further includes: transmitting, by the CU, an interface CU-DU message to a DU, where the interface CU-DU message includes at least one RRC message and a path identifier over which each transmitting at least one RRC message.

The second possible implementation of the second aspect provides another implementation of the transmission of the RRC message by the CU, and the DU may determine the transmission of each RRC message based on the identifier of the path over which the RRC message is transmitted.

Based on the second aspect, in a third possible implementation of the second aspect, the method further includes:

notification by the CU of the primary signaling radio path identifier to the terminal side device via the DU.

A third possible implementation of the second aspect allows the terminal side device to learn the main path, so that the main path for the CU, DU, and terminal side device is determined.

A third aspect of the embodiments of the present invention provides a method for transmitting data in duplex mode in a CU-DU architecture, including the following:

receiving a DU of a first message transmitted by the CU, the first message containing information indicating at least two uplink tunnel endpoints for data radio duplication mode that are at the interface between the CU and the DU; and transmitting, via the DU, a second message to the CU, where the second message contains information indicating at least two downlink tunnel endpoints for the data radio bearer that are at the interface between the CU and the DU, and identification of the main data radio bearer path. . In an implementation, at least two downlink tunnel endpoints are in a one-to-one correspondence with at least two uplink tunnel endpoints.

The third aspect corresponds to the first aspect and has beneficial effects similar to those of the first aspect.

Based on the third aspect, in the first possible implementation of the third aspect, the first message further contains information indicating to configure the duplication mode of the data radio bearer. The first possible implementation of the third aspect corresponds to the first possible implementation of the first aspect and has beneficial effects similar to those of the first possible implementation of the first aspect.

Based on the third aspect or the first possible implementation of the third aspect, in the second possible implementation of the third aspect, the main path identifier is the identifier indicated by the information contained in the second message of the path corresponding to only one of the at least two downlink tunnel endpoints. The second possible implementation of the third aspect corresponds to the second possible implementation of the first aspect and has similar beneficial effects to those of the second possible implementation of the first aspect.

Based on any one of the third aspect of the second possible implementation of the third aspect, in the third possible implementation of the third aspect, the first message further comprises information indicating an uplink tunnel endpoint of at least two uplink tunnel endpoints corresponding to the main path; or the second message further comprises information indicating a downlink tunnel endpoint of at least two downlink tunnel endpoints that corresponds to the main path; or an uplink tunnel endpoint of at least two uplink tunnel endpoints that corresponds to the main path is predetermined by the protocol; or a downlink tunnel endpoint of at least two downlink tunnel endpoints that corresponds to the main path is predetermined by the protocol.

The third possible implementation of the third aspect corresponds to the third possible implementation of the first aspect and has similar beneficial effects to those of the third possible implementation of the first aspect.

A fourth aspect of the embodiments of the present invention provides a method for transmitting data in duplex mode in a CU-DU architecture, including the following:

receiving, by the DU, a signaling radio bearer identifier and indication information used to indicate to configure the signaling radio bearer duplication mode, which are transmitted by the CU; and transmitting, by the DU, to the CU, the signaling radio bearer duplication mode configuration and the primary signaling radio bearer path identifier.

The fourth aspect corresponds to the second aspect and has beneficial effects similar to those of the second aspect.

Based on the fourth aspect, in the first possible implementation of the fourth aspect, the method further includes:

receiving by the DU the interface CU-DU message transmitted by the CU, wherein

when the signaling radio bearer duplication mode is inactive, the interface CU-DU message includes one RRC message belonging to the signaling radio bearer, and the DU transmits one RRC message to the terminal side device through the main path; or

when the signaling radio bearer duplication mode is active, the interface CU-DU message includes at least two RRC messages with the same PDCP sequence number that belong to the signaling radio bearer, and the DU transmits at least two RRC messages to the terminal side device through the main path, and at least one secondary path, respectively.

The first possible implementation of the fourth aspect corresponds to the first possible implementation of the second aspect and has similar beneficial effects to those of the first possible implementation of the second aspect.

Based on the fourth aspect, in a second possible implementation of the fourth aspect, the method further includes:

receiving, by the DU, a CU-DU interface message transmitted by the CU, where the CU-DU interface message includes at least one RRC message and a path identifier on which each of the at least one RRC message is transmitted.

The second possible implementation of the fourth aspect corresponds to the second possible implementation of the second aspect and has similar beneficial effects to those of the second possible implementation of the second aspect.

Based on the fourth aspect, in a third possible implementation of the fourth aspect, the method further includes: receiving by the DU a CU-DU interface message transmitted by the CU, where the CU-DU interface message includes an RRC message, wherein

if the PDCP duplicates the RRC message sequence number, the DU transmits the RRC message to the terminal side device via the secondary path; or, if the PDCP sequence number of the RRC message is not duplicated, the DU sends the RRC message to the terminal side device via the main path.

Using a third possible implementation of the fourth aspect, the DU may determine if the PDCP duplicated the received RRC message sequence number to determine whether the RRC message should be sent on the primary or secondary path.

A fifth aspect of the embodiments of the present invention provides an access network side device, and the access network side device includes a receiving unit and a transmitting unit. The receiving unit is configured to perform the receiving actions in the first aspect, the second aspect, the third aspect, the fourth aspect, or possible implementations thereof, and the transmitting unit is configured to perform the transmitting actions in the first aspect, or possible implementations thereof.

The access network side device provided in the fifth aspect may be a stand-alone CU or a stand-alone DU, or may be a chip system in a CU or a chip system in a DU. The chip system includes a processor consisting of at least one logic circuit and a memory consisting of at least one logic circuit. Each logic circuit includes at least one transistor (eg, a FET) connected by wires. Each transistor is made from a semiconductor material. In addition, the receiving unit and the transmitting unit are, respectively, a receiving scheme and a transmitting scheme in a particular implementation. The access network side device may further include other electronic lines, such as lines used to connect the receive circuit and the transmission circuit, and a radio frequency antenna used to transmit the signal. The technical solution provided in the fifth aspect has technical effects equivalent to those described above in the respective implementations. See the above implementations for details.

A sixth aspect of embodiments of the present invention provides a computer storage medium. The computer storage medium includes program code, and the program code is used to implement the technical solution provided in the first aspect, the second aspect, the third aspect, the fourth aspect, or possible implementations thereof. The technical solution provided in the sixth aspect has technical effects equivalent to those described above in the respective implementations. See the above implementations for details.

A seventh aspect of embodiments of the present invention provides a communication system. The communication system includes CU and DU. The CU is configured to implement the method in the first aspect, the second aspect, or possible implementations thereof, and the DU is configured to implement the technical solutions provided in the third aspect, the fourth aspect, or possible implementations thereof. The technical solution provided in the seventh aspect has technical effects equivalent to those described above in the respective implementations. The detailed description is set out above.

Brief description of the drawings

Fig. 1 is an architectural diagram of a duplication mode defined for a radio channel according to an embodiment of the present invention;

Fig. 2A-2C are block diagrams of the duplication mode in the CU-DU architecture according to an embodiment of the present invention;

Fig. 3A-3C are other duplication mode diagrams in a CU-DU architecture according to an embodiment of the present invention;

Fig. 4 is a flowchart of a method for transmitting data in duplex mode in a CU-DU architecture according to an embodiment of the present invention;

Fig. 5 is a flowchart of a method for transmitting data in duplex mode in a CU-DU architecture according to an embodiment of the present invention; and

Fig. 6 is a block diagram of an access network side device according to an embodiment of the present invention.

Implementation of the invention

In the schematic architectural diagram of the protocol stack of the radio communication system shown in FIG. 1, the radio communication system includes a terminal side device and an access network side device.

The device on the terminal side can be a stand-alone terminal or a chip system in the terminal. A terminal, also called a user equipment (UE) or a mobile station, includes mobile phones, IoT portable devices, wearable devices, and the like.

The access network side device may be a standalone radio access device or a chip system in the radio access device. The radio access device may be a wireless LAN base station or access point, and includes an RRC layer, a PDCP layer, an RLC layer, a MAC layer, a PHY layer, and the like. Base stations can be classified into two types: macro base stations (macro base station) and small base stations. Small base stations are further classified into micro base stations, pico base stations, and the like. The wireless LAN access point may be a router, a switch, or the like. A WLAN access point can provide Wireless Fidelity (Wi-Fi) signal coverage.

At least one radio channel (radio bearer, RB) is established between the device on the terminal side and the device on the access network side for data transmission. The data may include signaling data or overhead data. The radio bearer mainly used for signaling data transmission is signaling radio bearer (SRB) and the radio bearer mainly used for signaling data transmission is data radio bearer (DRB). These services include enhanced mobile broadband (eMBB) data, massive machine-type communications (mMTC) data, ultra-reliable low-latency communications (URLLC) data etc.

In the architectural diagram of the radio communication system shown in FIG. 1, for uplink transmission, the transmitting side is a terminal side device and the receiving side is an access network side device; and for downlink transmission, the transmitting side is an access network side device and the receiving side is a terminal side device.

For a radio bearer between a transmitting side and a receiving side, the radio bearer duplication mode includes configuring an appropriate set of protocol layer objects between the transmitting side and the receiving side. This set of protocol layer entities includes one PDCP entity, at least two RLC entities corresponding to the PDCP entity, at least one MAC entity corresponding to at least two RLC entities, and at least one PHY entity. , corresponding to at least one MAC object. For the signaling radio bearer, the set of protocol layer entities further includes one RRC entity corresponding to the PDCP entity. Perhaps for the data radio, the set of protocol layer objects may further include one SDAP object (Service Data Adaptation Protocol, SDAP) in the SDAP layer corresponding to the PDCP object.

In FIG. 1, in the duplication mode of one radio channel, a path is established between each RLC entity and the MAC entity. The RLC entity identifier may be used to indicate the path. Accordingly, the path identifier may be used to indicate the RLC entity. Therefore, the path identifier and the RLC entity identifier are interchangeable. In some technical literature, a path in redundant mode is also referred to as a leg.

Alternatively, in single radio bearer duplication mode, different paths are different logical channels with different logical channel identifiers. Therefore, the radio channel corresponds to at least two logical channels. The two logical channels may belong to the same logical channel group (LCG) or to different logical channel groups.

Alternatively, in single radio bearer duplication mode, at least two paths belong to the same logical channel and have the same logical channel identifier. Therefore, the radio channel corresponds to one logical channel. In this case, to distinguish between different paths, different paths may have the same logical channel identifier but different path identifiers.

In FIG. 1, in the single radio bearer duplication mode, the transmitting side and the receiving side both include at least one PDCP entity, a first RLC entity corresponding to one PDCP entity, and a second RLC entity corresponding to one PDCP entity. The first RLC entity corresponds to the first path and the second RLC entity corresponds to the second path. The transmitting side transmits to the receiving side data on the first path in cell 1b or cell group 1 that corresponds to the first path, and the receiving side receives on cell 1b or cell group 1 that corresponds to the first path, the data on the first path transmitted by the transmitting side. The transmitting side transmits data to the receiving side on the second path in cell 2b or cell group 2, which corresponds to the second path, and the receiving side receives data on the second path in cell 2b or cell group 2, which corresponds to the second path. After activation of the duplication mode, data from one PDCP entity is transmitted to the second RLC entity of the transmitting side and the first RLC entity of the transmitting side in duplicate. For example, after duplicating the PDCP data, the entity sends data to both the first RLC entity and the second RLC entity for transmission in duplicate; or after one RLC entity of the first RLC entity and the second RLC entity duplicates data, one RLC entity and the other RLC entity transmit data in duplicate.

In the CU-DU architecture in which carrier aggregation technology is further introduced, a path corresponding to a primary cell group (cell set including a primary cell) is a primary path, and accordingly, an RLC entity on the primary path is a primary RLC entity; and a path corresponding to a group of secondary cells (a set of cells including only at least one secondary cell) is a secondary path, and accordingly, an RLC entity on the secondary path is a secondary RLC entity.

Alternatively, the access network side device may include a primary path information element in the PDCP configuration of the radio channel sent to the terminal side device, wherein the primary path information element contains a cell group identifier (CellGroupId) and a path identifier corresponding to the identifier cell groups. And thus, the cell group indicated by the cell group ID is the main cell group, and the path indicated by the path ID is the main path. A path not specified in the primary path information element is a secondary radio path, and a cell group not specified in the primary path information element is a secondary cell group.

As shown in FIG. 2A-2C and FIG. 3A to 3C, when the device on the access network side is a CU-DU architecture, the PDCP layer is located in the CU, while the RLC layer, MAC layer, and PHY layer are in the DU. Therefore, various data that is sent from the PDCP layer to the RLC layer is sent from the CU to the DU. In FIG. 2A-2C, in single radio bearer duplication mode, at least two RLC entities are in one DU. In FIG. 3A-3C, in single radio bearer duplication mode, two RLC entities of at least two RLC entities are in different DUs.

Connections between CU and DU include: CU-DU control plane connection used to set up SRB, DRB and user context, and CU-DU user plane connection used to transfer data over DRB. Through the use of the General Packet Radio Service (GPRS) tunnel protocol, the user plane CU-DU connection is also referred to as a user plane tunnel. The user plane tunnel is a path between an uplink tunnel endpoint and a downlink tunnel endpoint that is in direct correspondence with an uplink tunnel endpoint. Once established, the user plane tunnel can be identified by the uplink tunnel endpoint or the downlink tunnel endpoint of the user plane tunnel.

When the access network side device is a CU-DU architecture, the DU to CU transmission is an uplink transmission, and the CU to DU transmission is a downlink transmission. In some technical literature, a CU-DU connection is referred to as an F1 connection, a CU-DU user plane connection is an F1-U connection, and a CU-DU control plane connection is an F1-C connection. Accordingly, a CU may include a user plane CU and a control plane CU, and the connection is referred to in some literature as an E1 connection in the control plane CU.

Alternatively, in FIG. 3A-3C, when the CU determines to configure the radio bearer shadow mode, the CU indicates a DU including at least one radio bearer shadow mode RLC entity to determine whether the shadow mode can be activated or deactivated for the radio bearer. The DU that receives the notification determines, based on the signal measurement result or other information, to activate or deactivate the radio bearer duplication mode, and instruct, using the MAC layer message, the device on the terminal side to activate or deactivate the radio bearer duplication mode.

Perhaps in Fig. 3A-3C, when the CU determines whether to activate or deactivate the radio bearer shadow mode, the CU notifies all DUs (e.g., including at least DU1 and DU2) including RLC entities in the radio bearer shadow mode that the radio bearer shadow mode activated or deactivated.

Perhaps in Fig. 3A-3C, when the DU determines whether to activate the radio bearer duplication mode, the DU notifies the CU and other DUs including other RLC entities that the radio bearer duplication mode is activated or deactivated.

In the following embodiments of the present invention, the data radio bearer duplication method is implemented in the CU-DU architecture, and as the signaling radio bearer duplication mode is implemented separately in the CU-DU architecture.

The first embodiment of the present invention provides a data transmission method in a CU-DU architecture applied to a data radio bearer duplication (DRB) mode scenario in a CU-DU architecture. Fig. 4 is a schematic flowchart of a data transmission method. The first embodiment of the present invention includes the following content.

401. The CU transmits a first message in the DU, where the first message contains information indicating at least two uplink tunnel endpoints, for data radio bearer duplication mode, that are on the interface between the CU and the DU,

The CU may determine that the data radio bearer duplication mode is to be configured and send a first message (eg, UE context setup/change request) in the DU on the CU-DU interface. The CU may carry information indicating at least two uplink tunnel endpoints and a data radio bearer identifier in the first message. Information indicating at least two uplink tunnel endpoints includes an address, such as an Internet Protocol (IP) address, of each of the at least two uplink tunnel endpoints, and an identifier , for example, the tunnel endpoint identifier (TEID) of each of the at least two uplink tunnel endpoints.

In a possible implementation, the structure of the first message on the CU-DU interface is as follows:

UE context setup/modification request

{...

DRBs to be setup list

> DRB ID (DRB ID)

> Tunnels to be setup list

>> Tunnels setup Item IEs

>>> Path Identity (Optional) or Mandatory

>>> UL Tunnel Endpoint Required

...}

402. The CU receives a second message sent by the DU, where the second message contains information indicating at least two downlink tunnel endpoints for a data radio bearer that are on the interface between the CU and the DU, and a primary radio bearer path identifier. . In one implementation, at least two downlink tunnel endpoints correspond to each other, at least two uplink tunnel endpoints.

After the DU receives the first message, since the identifier of one data radio bearer corresponds to information indicating at least two uplink tunnel endpoints in the first message, the DU can learn from the first message that the data transmission duplication mode should be set. radio channel. Possibly, the first message may further carry indication information, where the indication information explicitly indicates that the data radio duplication mode should be set. From the indication of the first message, the DU learns that the data radio duplication mode is to be set.

In step 402, the DU sends a second message (eg, UE context setup/change response) to the CU on the CU-DU interface to establish at least two user plane CU-DU tunnels on the interface between the CU and the DU, for duplication mode. data radio channel. In an implementation, the DU may carry information indicating at least two downlink tunnel endpoints in a second message, where at least two downlink tunnel endpoints are unambiguous, corresponding to at least two endpoints. uplink tunnel. Information indicating at least two downlink tunnel endpoints includes addresses (eg, Internet Protocol addresses) of at least two downlink tunnel endpoints and an identifier (eg, TEID) of each, at least two downlink tunnel endpoints. To further make user plane CU-DU tunnel endpoints corresponding to paths corresponding to at least two RLC entities in the DU, the second message further comprises information indicating a path identifier corresponding to each of at least one of at least one of two endpoints of the downlink tunnel. Possibly, the second message further comprises information indicating a cell group corresponding to a path corresponding to each of at least one of the at least two downlink tunnel endpoints. Thus, the CU can learn the match among any combination of uplink tunnel endpoint, downlink tunnel endpoint, path, and cell group in redundant mode.

In an exemplary implementation, after the CU control plane determines that the data radio duplication mode is to be configured, the CU control plane configures information indicative of at least two uplink tunnel endpoints, carries the information in the first message, and sends the first message in the DU over the control plane CU-DU connection. The CU control plane further sends information indicating at least two uplink tunnel endpoints to the CU user plane.

In another exemplary implementation, when the CU user plane determines that the data radio bearer duplication mode is to be configured, the CU user plane allocates information on at least two uplink tunnel endpoints and sends information on at least two tunnel endpoints uplink to the CU control plane. The control plane CU carries information indicative of at least two uplink tunnel endpoints in a first message and sends the first message through the control plane CU-DU connection. In addition, after the CU control plane receives information of at least two downlink tunnel endpoints notified by the DU in the second message, the control plane notifies information indicating at least two downlink tunnel endpoints, in the CU user plane The CU control plane may receive on the CU-DU interface of the control plane the second message sent by the DU.

Through executions 401 and 402, one user plane tunnel is established between one uplink tunnel endpoint and one corresponding downlink tunnel endpoint between the CU and the DU. In the duplication mode, at least two user plane tunnels are established between the CU and the DU.

Possibly, the second message contains information indicating that the main path corresponds to a certain one of at least two downlink tunnel endpoints, so that the user plane tunnel to which this certain one downlink tunnel endpoint belongs corresponds to the main path, and other user plane tunnels correspond to secondary paths. For example, the DU indicates in the second message the downlink tunnel endpoint 1 corresponding to the data radio bearer and the downlink tunnel endpoint 2 which corresponds to the data radio bearer, and indicates the path identifier associated with the downlink tunnel endpoint 1. Therefore, the path identifier associated with downlink tunnel endpoint 1 is the base path identifier. In this case, the defined single downlink tunnel endpoint may be referred to as the primary tunnel endpoint. When the duplication mode is disabled, the CU and DU transmit service data at the primary tunnel endpoint through the primary path corresponding to the primary tunnel endpoint and do not transmit service data at other tunnel endpoints via paths corresponding to other tunnel endpoints.

In an alternative implementation, instead of 401 and 402, the main path may be determined by the CU and indicated in the first message to be sent to the DU. In this case, the second message may not contain the primary path identifier. Whether the primary path identifier is carried in the first message or the second message, the CU is clear and the DU knows which user plane tunnel corresponds to the primary path. Thus, the connection between the user plane tunnel and the main path is established in redundant mode. Accordingly, a connection can be established between another user plane tunnel and a secondary path.

Optionally, the second message may include identifiers of at least two paths respectively corresponding to at least two downlink tunnel endpoints. The identification data of at least two paths includes the identification data of the main path. In order to make the CU know which of the at least two paths is the main path, the second message not only includes the identifiers of the at least two paths, but also specifically indicates which path is the main path.

Optionally, the second message may include a path identifier corresponding to a specific one of the at least two downlink tunnel endpoints. In this case, in the second message, since only one downlink tunnel endpoint corresponds to a path, the CU may know that the path corresponding to this downlink tunnel endpoint is the main path. Possibly, the second message may explicitly indicate that the path identifier corresponding to the downlink tunnel endpoint is the base path identifier.

It is possible which of the at least two downlink tunnel endpoints or which of the at least two uplink tunnel endpoints corresponding to the main path is predefined by the protocol. In one exemplary implementation, a specific one of at least two uplink tunnel endpoints or a specific one downlink tunnel endpoint is predefined to match the path, without specifying a path corresponding to any other tunnel endpoints. In this case, the CU and the DU learn from the protocol predetermination that the path corresponding to the predefined uplink tunnel endpoint or the predefined downlink tunnel endpoint is the main path. In another possible implementation, the second message indicates the path identifiers respectively corresponding to all at least two downlink tunnel endpoints, and the CU and DU learn, from the protocol predetermination, that the path corresponding to the predefined downlink tunnel endpoint is the main tract.

In an exemplary implementation, the uplink tunnel endpoint that first appears in the list of tunnel to be established corresponding to the data radio bearer ID in the first message corresponds to the main path. For example, the list includes uplink tunnel endpoint 1 and uplink tunnel endpoint 2, and hence uplink tunnel endpoint 1 corresponds to the main path. When the DU sends the second message, the first user plane tunnel is established using the downlink tunnel endpoint first appearing in the list of established tunnels and the uplink tunnel endpoint first appearing in the first message, where the user plane tunnel corresponds to the main path. For example, the DU indicates in the second message that the data radio bearer ID corresponds to downlink tunnel endpoint 1 and downlink tunnel endpoint 2. Downlink tunnel endpoint 1 and uplink tunnel endpoint 1 implement a first user plane tunnel, and this user plane tunnel is associated with the main path. In other words, the path identifier corresponding to the downlink tunnel endpoint 1 is the base path identifier. For example, Downlink Tunnel Endpoint ID 1 corresponds to Logical Channel ID 1 and hence Logical Channel ID 1 is the Main Path ID.

Additionally, the CU may indicate in the first message which of the at least two uplink tunnel endpoints should correspond to the primary path (although the CU does not know the primary path identifier at this time). For example, the CU indicates that uplink tunnel endpoint 1 corresponds to the main path. The DU then learns that the uplink tunnel endpoint 1 must correspond to the main path, and therefore the identity of the main path corresponding to the uplink tunnel endpoint 1 is indicated in the second message. For example, the DU includes downlink tunnel endpoint 1 information and downlink tunnel endpoint 2 information in the second message. Downlink tunnel endpoint 1 corresponds to uplink tunnel endpoint 1, and therefore user plane tunnel 1 is established. The downlink tunnel endpoint 2 corresponds to the uplink tunnel endpoint 2, and therefore the user plane tunnel 2 is established. The DU learns from the CU indication that the downlink tunnel endpoint 1 corresponding to the uplink tunnel endpoint 1 needs to match the main path, and further associates the main path identifier with the downlink tunnel endpoint 1, carries the main path identifier in the second message and sends a second message to the CU so that the CU knows about the Primary Path ID. For example, the CU analyzes the second message to find out that downlink tunnel endpoint 1 corresponds to uplink tunnel endpoint 1, and the path identifier associated with downlink tunnel endpoint 1 is the primary path identifier.

Alternatively, the DU may determine which of the at least two downlink tunnel endpoints should correspond to the main path, and indicate in the second message the downlink tunnel endpoint corresponding to the main path among the at least two endpoints. downlink tunnel points. For example, the DU includes downlink tunnel endpoint 1 and downlink tunnel endpoint 2, which correspond to a data radio bearer, in the second message, and indicates that downlink tunnel endpoint 1 is the primary path. Then, the path identifier associated with downlink tunnel endpoint 1 is the base path identifier.

Alternatively, the method further includes: 403, the CU notifies the primary data radio path identifier to the terminal side device via the DU. The CU may further notify the cell group ID (namely, the main cell group) corresponding to the main path to the device on the terminal side. The content notified to the CU at step 403 may be carried in a PDCP configuration of a data radio bearer. After receiving the PDCP configuration, the DU passes through the PDCP configuration to the terminal side device. When the CU includes the CU control plane and the CU user plane, the CU control plane can complete the PDCP layer configuration, or that the CU user plane can complete the PDCP layer configuration and notifies the PDCP layer configuration to the CU control plane.

For example, the CU receives the cell group configuration (CellGroupConfig) in the second message sent by the DU, and obtains the cell group identifier (CellGroupId) from the configuration. In particular, the cell group ID can be presented as a separate information element in the second message, and therefore the CU does not need to obtain the cell group ID by reading the cell group configuration. The CU uses the above method to obtain a base path identifier, such as a base path logical channel identifier. The CU adds the Cell Group ID and the Primary Path ID to the PDCP configuration.

It is possible that the CU control plane sends to the CU user plane the received cell group identity and the main path identity together with the corresponding radio bearer identity. The CU user plane writes the cell group ID and the primary path ID in the PDCP configuration. The CU user plane sends the PDCP configuration to the CU control plane, so the CU control plane sends the PDCP configuration to the terminal side device via the DU.

In one example, the CU determines the device's DRB1 duplication mode configuration on the terminal side. Then, one user plane tunnel is established between CU and DU1 for DRB1, and one user plane tunnel is established between CU and DU2 for DRB1. The CU may notify DU1 and DU2 that the shadow mode is configured for DRB1, so that DU1 or DU2 further instructs, using the MAC layer message, the terminal side device to activate or deactivate the shadow mode.

According to the solution provided in the first embodiment of the present invention, the correspondence between an uplink tunnel endpoint, a downlink tunnel point, and a path is established in redundant mode, and the method of determining the main path is explicitly specified. Thus, the duplication mode is implemented for the radio channel in the CU-DU architecture.

The second embodiment of the present invention provides a data transmission method in a CU-DU architecture applied to a signaling radio bearer (SBR) mode scenario in a CU-DU architecture. Fig. 5 is a schematic flowchart of a data transmission method. The second embodiment of the present invention includes the following content.

501. The CU sends to the DU the signaling radio bearer identifier and indication information used to indicate to configure the signaling radio bearer duplication mode.

At 501, the CU determines that the signaling radio bearer duplication mode is to be configured, generates a third message (eg, UE context setup/change request), and includes the signaling radio bearer identifier in the third message and indication information instructing to configure the signaling radio bearer duplication mode. For example, in the third message, the CU instructs the DU to set SRB1 and SRB2, and instructs the DU to configure the SRB1 duplication mode. Possibly, the CU may further indicate the signaling radio bearer active time such that the DU activates the signaling radio bearer during the active time.

502. The CU receives the signaling radio bearer duplication mode configuration and the primary signaling radio bearer path identification, which are transmitted by the DU.

Alternatively, the shadowing mode configuration transmitted by the DU includes identifiers of at least two signaling radio paths.

Alternatively, the identifiers of at least two signaling radio paths or the primary radio path identifier may be determined by the DU and may be notified from the DU to the CU at 502, or may be determined by the CU and notified from the DU to the DU at 501.

In step 502, the DU generates a fourth message (eg, a UE context setup/change response) and carries in the fourth signaling signaling radio bearer duplication mode configuration at the RLC layer, MAC layer, and PHY layer and also carry identifiers of at least two signaling radio bearer paths. to set the signaling radio channel duplication mode. The duplication mode configuration further includes a cell group identifier corresponding to each signaling radio path. The fourth message further includes a cell group identifier (namely, the main cell group) corresponding to the main path of the signaling radio bearer. For example, the DU includes a cell group configuration (CellGroupConfig) in the fourth message, and the cell group configuration includes identifiers of at least two signaling radio paths. The fourth message may further include a base path identifier, and the base path identifier is represented as a separate information element in the fourth message.

For example, the CU receives the cell group configuration included in the second message sent by the DU and obtains the cell group ID from the cell group configuration. In particular, the cell group ID may be presented as a separate information element in the second message, and therefore the CU obtains the cell group ID without reading the cell group configuration. In addition, the CU uses the above method to obtain a base path identifier, such as a base path logical channel identifier. The CU adds the Cell Group ID and the Primary Path ID to the PDCP configuration. The CU generates a radio bearer configuration (RadioBearerConfig), where the radio bearer configuration includes the PDCP configuration. Finally, the CU generates an RRC reconfiguration message containing the radio bearer configuration and cell group configuration, which is sent to the DU. The CU forwards the RRC reconfiguration message to the UE via the DU. After the signaling radio bearer duplication mode is configured at 501 and 502 (perhaps during the duplication mode active time), the duplication mode is activated. The CU may duplicate the generated RRC message at the PDCP layer, and then send the duplicated RRC message to the DU. After the shadow mode configuration is invalid or the shadow mode active time expires, the shadow mode becomes inactive and the CU no longer duplicates any generated RRC message.

Therefore, based on 501 and 502, the method further includes 503, where the CU sends an RRC message to the DU in the following several possible ways:

503A. The CU transmits a fifth message to the DU, where, when the signaling radio bearer duplication mode is inactive, the fifth message includes one RRC message belonging to the signaling radio bearer; or, when the signaling radio bearer duplication mode is active, the fifth message includes at least two RRC messages with the same PDCP sequence number that belong to the signaling radio bearer.

At 503A, if the message received by the DU on the CU-DU interface includes only one RRC message, for example, if the DL RRC message send message includes only one RRC message, the DU transmits only one RRC message to the device on the terminal side via any (eg, main path) of at least two paths. If the message received by the DU at the CU-DU control plane interface includes at least two RRC messages with the same PDCP sequence number, the DU transmits at least two RRC messages to the terminal side device via at least two paths, respectively.

503B. The CU transmits a fifth message in a DU, where the fifth message includes at least one RRC message and a path identifier on which each of the at least one RRC message is transmitted.

At 503B, the CU may indicate the identifier of the path on which each RRC message is transmitted, so that the DU transmits, based on the path identifier indicated by the CU, each RRC message to the terminal side device via the path on which the RRC message is transmitted.

503C. The CU sends a fifth message to the DU, where the fifth message includes an RRC message. The DU determines if the PDCP duplicates the RRC message sequence number. If the PDCP sequence number is duplicated, the DU sends an RRC message to the terminal side device on the secondary path. If the PDCP sequence number is not duplicated, the DU sends an RRC message to the terminal side device on the main path.

At 503C, the DU may record the PDCP sequence number of each RRC message received by the CU so that when the DU receives a specific RRC message, the DU compares with the PDCP-recorded sequence numbers to determine if the PDCPs duplicate the specific RRC message's sequence number.

Further, in order to prompt the terminal side device to learn about the shadow mode configuration, the CU may further generate, based on the shadow mode configuration received from the DU, the shadow mode configuration information to be sent to the terminal side device. The method further includes: the CU transmits the shadowing mode configuration information to the terminal-side device via the DU, where the shadowing mode configuration information includes at least one of the following: identifiers of at least two signaling radio link paths, identifier the main path of the signaling radio channel. The Signaling Radio Primary Path Identifier may be used as part of the shadow mode layer PDCP configuration. It is possible that the shadowing mode configuration information further includes an RLC layer configuration, a MAC layer configuration, and a PHY layer configuration, and the like. duplication mode.

In the solution provided in the second embodiment of the present invention, the CU instructs the DU to configure a signaling radio bearer, thereby obtaining a signaling radio bearer configuration made by the DU. Thus, the duplication mode is implemented for the signaling radio bearer in the CU-DU architecture.

The third embodiment of the present invention provides a device on the access network side. In the block diagram of the access network side device shown in FIG. 6, the access network side device includes a receiving section 601 and a transmitting section 602.

The access network side device may be a CU in the first embodiment or a chip in the CU. Transmitting unit 602 is configured to transmit a first message in a DU, where the first message contains information indicative of at least two uplink tunnel endpoints for data radio duplication mode that are at the interface between the CU and the DU. The receiving unit 601 is configured to receive a second message sent by the DU, where the second message contains information indicating at least two downlink tunnel endpoints for a data radio link that are on the interface between the CU and the DU, and a base path identifier data radio channel. In an implementation, at least two downlink tunnel endpoints are in a one-to-one correspondence with at least two uplink tunnel endpoints. In this case, the receiving block 601 and the sending block 602 may respectively perform a receiving action and a sending action of the CU in the first embodiment. The detailed description is clear from the description of the actions of the CU in the first embodiment. Details are not described here again.

The access network side device may be a DU in the first embodiment or a chip in the DU. The receiving unit 601 is configured to receive a first message sent by the CU, where the first message contains information indicative of at least two uplink tunnel endpoints for the data radio duplication mode that is on the interface between the CU and the DU; and the sender 602 is configured to send a second message to the CU, where the second message contains information indicating at least two downlink tunnel endpoints for the data radio that are on the interface between the CU and the DU, and a base path identifier data radio channel. In an implementation, at least two downlink tunnel endpoints are in a one-to-one correspondence with at least two uplink tunnel endpoints. In this case, the receiving block 601 and the sending block 602 may respectively perform a receiving action and a sending action of a DU in the first embodiment. A detailed description is set forth in the description of the operation of the DU in the first embodiment. Details are not described here again.

The access network side device may be a CU in the second embodiment or a chip in the CU. The transmission unit 602 is configured to transmit, to the DU, a signaling radio bearer identifier and indication information used to indicate to configure the signaling radio bearer duplication mode; and the receiving unit 601 is configured to receive the configuration of the signaling radio bearer duplication mode and the signaling radio main path ID that are sent by the DU. In this case, the receiving block 601 and the sending block 602 may respectively perform a receiving action and a sending action of the CU in the second embodiment. The detailed description corresponds to the description of the actions of the CU in the second embodiment. Details are not described here again.

The access network side device may be a DU in the second embodiment or a chip in the DU. The receiving unit 601 is configured to receive the signaling radio bearer identifier and indication information used to indicate to configure the signaling radio bearer duplication mode which are transmitted by the CU; and the transmitting unit 602 is configured to transmit to the CU the signaling radio bearer duplication mode configuration and the primary signaling radio bearer path identifier. In this case, the receiving block 601 and the sending block 602 may respectively perform a receiving action and a sending action of a DU in the second embodiment. The detailed description is clear from the description of the actions of the CU in the second embodiment. Details are not described here again.

In a specific implementation, the receive block 601 and the transmit block 602 are respectively a receive circuit and a transmit circuit. The access network side apparatus may further include a processing circuit, for example in the form of at least one processor(s), for realizing generation and processing of the above messages. The access network side device may further include other electronic lines, such as lines used to connect the receive circuit and the send circuit. When the access network side device is a DU, the access network side device may further include an RF antenna for sending various information to the terminal side device.

In another specific implementation, the access network side device may include a processor and memory. The memory stores the code, and when the code is called by the processor, the method performed by the CU or DU in the above method embodiments can be executed. In particular, the code includes a plurality of data structures, and each data structure is used to implement the functions of the above protocol layers. When the access network side device is a CU, a control plane CU device, a user plane CU device, or a chip in the CU, the data structures contained in the code are used to implement at least the functions of the PDCP layer. In this case, the receive block 601 may be the data structure input interface and the transmit block 602 may be the data structure output interface. When the access network side device is a DU, a control plane DU, a user plane DU, or a chip in the DU, the data structures contained in the code are used to implement at least the functions of the RLC layer. The receive block 601 may be an input interface of data structures, and the transmit block is an output interface of data structures.

One skilled in the art will understand that embodiments of the present invention may be provided as a method, system, or computer program product. Therefore, the present invention may take the form of hardware-only embodiments, software-only embodiments, or combination of software and hardware embodiments. In addition, the present invention may use a form of a computer program product that is implemented on one or more chip systems or computer storage media (including, but not limited to, disk memory, CD-ROM, optical memory, and so on) that include computer program code.

The present invention has been described with reference to flowcharts and/or flowcharts of a method, apparatus (system), and computer program product in accordance with embodiments of the present invention. It should be understood that computer program instructions may be used to implement each process and/or each block in flowcharts and/or flowcharts, or a combination of a process and/or block in flowcharts and/or flowcharts. These computer program instructions may be provided to a general purpose computer, a special purpose computer, an embedded processor, or the processor of any other programmable data processing device to generate a machine, so that the instructions are executed by the computer or processor of any other programmable data processing device generated by the device to implement a particular function in one or multiple processes in flowcharts and/or one or more blocks in flowcharts.

These computer program instructions may be stored in computer readable memory, which may instruct the computer or any other programmable data processing device to operate in a certain way, such that the instructions stored in computer readable memory generate an artifact that includes the instruction device. The instruction device implements a particular function in one or more processes in flowcharts and/or in one or more blocks in flowcharts.

These computer program instructions can be downloaded to a computer or other programmable processing device such that a series of operations and steps are executed on the computer or other programmable device, thereby generating a computer-implemented process. Therefore, instructions executable on a computer or other programmable device provide steps for implementing a specific function in one or more processes in flowcharts and/or in one or more blocks in flowcharts.

Claims (33)

1. A method for transmitting data in duplication mode in a central unit-distributed unit (CU-DU) architecture, comprising the steps of: transmitting, by the CU, a first message to the DU, the first message containing information indicating at least two uplink tunnel endpoints at the interface between the CU and the DU for a data radio duplication mode; and receiving by the CU a second message transmitted by the DU, the second message containing information indicating at least two downlink tunnel endpoints at the interface between the CU and the DU for a data radio bearer and a base path logical channel identifier of at least two logical channels corresponding to the radio data transmission channel. 2. The method of claim 1, wherein said at least two downlink tunnel endpoints are in a one-to-one correspondence with at least two uplink tunnel endpoints. 3. The method of claim 1, wherein the data radio bearer duplication mode is that, for the data radio bearer, one Packet Data Convergence Protocol (PDCP) entity at the PDCP layer corresponds to at least two Radio Link Control (RLC) entities at the RLC layer. and some or all of the data at the PDCP entity is transmitted at least two RLC entities in duplicate. 4. The method of claim 1, wherein the CU is configured to implement Packet Data Convergence Protocol (PDCP) layer functions and radio resource control (RRC) layer functions, and the DU is configured to implement physical layer (PHY) functions, access control layer functions to the medium (MAC) and radio link control (RLC) layer functions. 5. The method of claim 1, wherein the base path logical channel identifier is a path identifier corresponding to one of the at least two downlink tunnel endpoints. 6. The method according to any one of claims 1 to 5, further comprising the step of the device at the terminal side is notified by the CU of the primary path identifier of at least two logical channels corresponding to the radio data link via the DU. 7. A method for transmitting data in duplication mode in a central unit-distributed unit (CU-DU) architecture, comprising the steps of: receiving, with the DU, a first message transmitted by the CU, the first message containing information indicating at least two uplink tunnel endpoints at an interface between the CU and the DU for a data radio duplication mode; and transmitting a second message to the CU using the DU, the second message containing information indicating at least two downlink tunnel endpoints at the interface between the CU and the DU for the data radio bearer and a main path logical channel identifier of at least two logical channels, corresponding to the radio data transmission channel. 8. The method of claim 7, wherein the at least two downlink tunnel endpoints are in a one-to-one correspondence with the at least two uplink tunnel endpoints. 9. The method of claim 7, wherein the data radio bearer duplication mode is that, for the data radio bearer, one Packet Data Convergence Protocol (PDCP) entity at the PDCP layer corresponds to at least two Radio Link Control (RLC) entities at the RLC layer. , and some or all of the data on the PDCP entity is transmitted on at least two RLC entities in duplicate. 10. The method of claim 7, wherein the CU is configured to implement Packet Data Convergence Protocol (PDCP) layer functions and radio resource control (RRC) layer functions, and the DU is configured to implement physical layer (PHY) functions, access control layer functions to the medium (MAC) and radio link control (RLC) layer functions. 11. The method of any one of claims 7-10, wherein the base path logical channel identifier is a path logical channel identifier corresponding to one of the at least two downlink tunnel endpoints. 12. The central unit (CU) for the duplication mode in the architecture is a central unit-distributed unit (CU-DU) containing a transmit unit and a receive unit, while the transmit unit is configured to transmit a first message to the DU, the first message containing information indicating at least two uplink tunnel endpoints located at an interface between a CU and a DU for a data radio duplication mode; a the receiving unit is configured to receive a second message transmitted by the DU, wherein the second message contains information indicating at least two downlink tunnel endpoints located at the interface between the CU and the DU for a data radio bearer, and a base path logical channel identifier of at least two logical channels corresponding to the data radio channel. 13. The CU of claim 12, wherein the at least two downlink tunnel endpoints are in a one-to-one correspondence with the at least two uplink tunnel endpoints. 14. The CU of claim 12, wherein the data radio bearer duplication mode is that, for the data radio bearer, one Packet Data Convergence Protocol (PDCP) entity in the PDCP layer corresponds to at least two Radio Link Control (RLC) entities in the RLC layer. , and some or all of the data on the PDCP entity is transmitted on at least two RLC entities in duplicate. 15. The CU according to claim 12, characterized in that it is configured to implement packet data convergence protocol (PDCP) layer functions and radio resource control (RRC) layer functions, and the DU is configured to implement physical layer (PHY) functions, control layer functions media access (MAC) and radio link control (RLC) layer functions. 16. The CU according to any one of claims 12-15, wherein the base path logical channel identifier is the path logical channel identifier of the path corresponding to one of the at least two downlink tunnel endpoints. 17. The CU according to any one of claims 12 to 16, wherein the transmission unit is further configured to notify the terminal side device of the base path logical channel ID of the at least two logical channels corresponding to the radio data link via the DU. 18. Distributed unit (DU) for the duplication mode in the architecture of the central unit-distributed unit (CU-DU), containing a receive unit and a transmit unit, while the receiving unit is configured to receive a first message transmitted by the CU, the first message containing information indicating at least two uplink tunnel endpoints located at the interface between the CU and the DU for a data radio duplication mode; a the transmission unit is configured to transmit a second message to the CU, the second message containing information indicating at least two downlink tunnel endpoints located at the interface between the CU and the DU for the data radio bearer, and a main path logical identifier of at least two logical channels corresponding to the data radio channel. 19. The DU of claim 18, wherein the at least two downlink tunnel endpoints are in a one-to-one correspondence with the at least two uplink tunnel endpoints. 20. The DU of claim 18, wherein the data radio bearer duplication mode is that, for the data radio bearer, one Packet Data Convergence Protocol (PDCP) entity in the PDCP layer corresponds to at least two Radio Link Control (RLC) entities in the RLC layer. , and some or all of the data on the PDCP entity is transmitted on at least two RLC entities in duplicate. 21. The DU of claim 18, wherein the CU is configured to implement Packet Data Convergence Protocol (PDCP) layer functions and radio resource control (RRC) layer functions, and the DU is configured to implement physical layer (PHY) functions, access control layer functions to the medium (MAC) and radio link control (RLC) layer functions. 22. A DU according to any one of claims 18-21, wherein the base path logical channel identifier is a logical path identifier corresponding to one of the at least two downlink tunnel endpoints. 23. Communication system containing the central unit (CU) according to any one of paragraphs. 12-17 and a distributed unit (DU) according to any one of paragraphs. 18-22. 24. Machine-readable storage medium that stores program code causing, when executed, the implementation of the method according to any one of paragraphs. 1-6. 25. Machine-readable storage medium that stores the program code causing, when executed, the implementation of the method according to any one of paragraphs. 7-11.

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